networking/tls.c

   1 /*
   2  * Copyright (C) 2017 Denys Vlasenko
   3  *
   4  * Licensed under GPLv2, see file LICENSE in this source tree.
   5  */
   6 //config:config TLS
   7 //config:       bool #No description makes it a hidden option
   8 //config:       default n
   9 //Note:
  10 //Config.src also defines FEATURE_TLS_SHA1 option
  11
  12 //kbuild:lib-$(CONFIG_TLS) += tls.o
  13 //kbuild:lib-$(CONFIG_TLS) += tls_pstm.o
  14 //kbuild:lib-$(CONFIG_TLS) += tls_pstm_montgomery_reduce.o
  15 //kbuild:lib-$(CONFIG_TLS) += tls_pstm_mul_comba.o
  16 //kbuild:lib-$(CONFIG_TLS) += tls_pstm_sqr_comba.o
  17 //kbuild:lib-$(CONFIG_TLS) += tls_aes.o
  18 //kbuild:lib-$(CONFIG_TLS) += tls_aesgcm.o
  19 //kbuild:lib-$(CONFIG_TLS) += tls_rsa.o
  20 //kbuild:lib-$(CONFIG_TLS) += tls_fe.o
  21
  22 #include "tls.h"
  23
  24 // works against "openssl s_server -cipher NULL"
  25 // and against wolfssl-3.9.10-stable/examples/server/server.c:
  26 #define ALLOW_RSA_NULL_SHA256  0  // for testing (does everything except encrypting)
  27
  28 //Tested against kernel.org:
  29 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE *** matrixssl uses this on my box
  30 //#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE
  31 //#define CIPHER_ID TLS_DH_anon_WITH_AES_256_CBC_SHA // SSL_ALERT_HANDSHAKE_FAILURE
  32 //^^^^^^^^^^^^^^^^^^^^^^^ (tested b/c this one doesn't req server certs... no luck, server refuses it)
  33 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 // SSL_ALERT_HANDSHAKE_FAILURE
  34 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  35 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 // ok, recvs SERVER_KEY_EXCHANGE
  36 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
  37 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384
  38 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  39 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
  40 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  41 //#define CIPHER_ID TLS_RSA_WITH_AES_256_GCM_SHA384 // ok, no SERVER_KEY_EXCHANGE
  42 //#define CIPHER_ID TLS_RSA_WITH_AES_128_GCM_SHA256 // ok, no SERVER_KEY_EXCHANGE
  43
  44 // works against wolfssl-3.9.10-stable/examples/server/server.c
  45 // works for kernel.org
  46 // does not work for cdn.kernel.org (e.g. downloading an actual tarball, not a web page)
  47 //  getting alert 40 "handshake failure" at once
  48 //  with GNU Wget 1.18, they agree on TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xC02F) cipher
  49 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES256-SHA256
  50 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES256-GCM-SHA384
  51 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES128-SHA256
  52 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES128-GCM-SHA256
  53 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -cipher AES128-SHA
  54 //        (TLS_RSA_WITH_AES_128_CBC_SHA - in TLS 1.2 it's mandated to be always supported)
  55 //#define CIPHER_ID1  TLS_RSA_WITH_AES_256_CBC_SHA256 //0x003D
  56 // Works with "wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.9.5.tar.xz"
  57 //#define CIPHER_ID2  TLS_RSA_WITH_AES_128_CBC_SHA    //0x002F
  58
  59 // bug #11456:
  60 // ftp.openbsd.org only supports ECDHE-RSA-AESnnn-GCM-SHAnnn or ECDHE-RSA-CHACHA20-POLY1305
  61 //#define CIPHER_ID3  TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 //0xC02F
  62 // host is.gd accepts only ECDHE-ECDSA-foo (the simplest which works: ECDHE-ECDSA-AES128-SHA 0xC009)
  63 //#define CIPHER_ID4  TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA  //0xC009
  64
  65
  66 #define TLS_DEBUG      0
  67 #define TLS_DEBUG_HASH 0
  68 #define TLS_DEBUG_DER  0
  69 #define TLS_DEBUG_FIXED_SECRETS 0
  70 #if 0
  71 # define dump_raw_out(...) dump_hex(__VA_ARGS__)
  72 #else
  73 # define dump_raw_out(...) ((void)0)
  74 #endif
  75 #if 0
  76 # define dump_raw_in(...) dump_hex(__VA_ARGS__)
  77 #else
  78 # define dump_raw_in(...) ((void)0)
  79 #endif
  80
  81 #if TLS_DEBUG
  82 # define dbg(...) fprintf(stderr, __VA_ARGS__)
  83 #else
  84 # define dbg(...) ((void)0)
  85 #endif
  86
  87 #if TLS_DEBUG_DER
  88 # define dbg_der(...) fprintf(stderr, __VA_ARGS__)
  89 #else
  90 # define dbg_der(...) ((void)0)
  91 #endif
  92
  93
  94 //TLS 1.2
  95 #define TLS_MAJ 3
  96 #define TLS_MIN 3
  97
  98 #define RECORD_TYPE_CHANGE_CIPHER_SPEC  20 /* 0x14 */
  99 #define RECORD_TYPE_ALERT               21 /* 0x15 */
 100 #define RECORD_TYPE_HANDSHAKE           22 /* 0x16 */
 101 #define RECORD_TYPE_APPLICATION_DATA    23 /* 0x17 */
 102
 103 #define HANDSHAKE_HELLO_REQUEST         0  /* 0x00 */
 104 #define HANDSHAKE_CLIENT_HELLO          1  /* 0x01 */
 105 #define HANDSHAKE_SERVER_HELLO          2  /* 0x02 */
 106 #define HANDSHAKE_HELLO_VERIFY_REQUEST  3  /* 0x03 */
 107 #define HANDSHAKE_NEW_SESSION_TICKET    4  /* 0x04 */
 108 #define HANDSHAKE_CERTIFICATE           11 /* 0x0b */
 109 #define HANDSHAKE_SERVER_KEY_EXCHANGE   12 /* 0x0c */
 110 #define HANDSHAKE_CERTIFICATE_REQUEST   13 /* 0x0d */
 111 #define HANDSHAKE_SERVER_HELLO_DONE     14 /* 0x0e */
 112 #define HANDSHAKE_CERTIFICATE_VERIFY    15 /* 0x0f */
 113 #define HANDSHAKE_CLIENT_KEY_EXCHANGE   16 /* 0x10 */
 114 #define HANDSHAKE_FINISHED              20 /* 0x14 */
 115
 116 #define TLS_EMPTY_RENEGOTIATION_INFO_SCSV       0x00FF /* not a real cipher id... */
 117
 118 #define SSL_NULL_WITH_NULL_NULL                 0x0000
 119 #define SSL_RSA_WITH_NULL_MD5                   0x0001
 120 #define SSL_RSA_WITH_NULL_SHA                   0x0002
 121 #define SSL_RSA_WITH_RC4_128_MD5                0x0004
 122 #define SSL_RSA_WITH_RC4_128_SHA                0x0005
 123 #define TLS_RSA_WITH_IDEA_CBC_SHA               0x0007  /* 7 */
 124 #define SSL_RSA_WITH_3DES_EDE_CBC_SHA           0x000A  /* 10 */
 125
 126 #define SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA       0x0016  /* 22 */
 127 #define SSL_DH_anon_WITH_RC4_128_MD5            0x0018  /* 24 */
 128 #define SSL_DH_anon_WITH_3DES_EDE_CBC_SHA       0x001B  /* 27 */
 129 #define TLS_RSA_WITH_AES_128_CBC_SHA            0x002F  /*SSLv3   Kx=RSA   Au=RSA   Enc=AES(128) Mac=SHA1 */
 130 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA        0x0033  /* 51 */
 131 #define TLS_DH_anon_WITH_AES_128_CBC_SHA        0x0034  /* 52 */
 132 #define TLS_RSA_WITH_AES_256_CBC_SHA            0x0035  /* 53 */
 133 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA        0x0039  /* 57 */
 134 #define TLS_DH_anon_WITH_AES_256_CBC_SHA        0x003A  /* 58 */
 135 #define TLS_RSA_WITH_NULL_SHA256                0x003B  /* 59 */
 136 #define TLS_RSA_WITH_AES_128_CBC_SHA256         0x003C  /* 60 */
 137 #define TLS_RSA_WITH_AES_256_CBC_SHA256         0x003D  /* 61 */
 138 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256     0x0067  /* 103 */
 139 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256     0x006B  /* 107 */
 140 #define TLS_PSK_WITH_AES_128_CBC_SHA            0x008C  /* 140 */
 141 #define TLS_PSK_WITH_AES_256_CBC_SHA            0x008D  /* 141 */
 142 #define TLS_DHE_PSK_WITH_AES_128_CBC_SHA        0x0090  /* 144 */
 143 #define TLS_DHE_PSK_WITH_AES_256_CBC_SHA        0x0091  /* 145 */
 144 #define TLS_RSA_WITH_SEED_CBC_SHA               0x0096  /* 150 */
 145 #define TLS_RSA_WITH_AES_128_GCM_SHA256         0x009C  /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESGCM(128) Mac=AEAD */
 146 #define TLS_RSA_WITH_AES_256_GCM_SHA384         0x009D  /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESGCM(256) Mac=AEAD */
 147 #define TLS_DHE_RSA_WITH_AES_128_GCM_SHA256     0x009E  /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESGCM(128) Mac=AEAD */
 148 #define TLS_DHE_RSA_WITH_AES_256_GCM_SHA384     0x009F  /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESGCM(256) Mac=AEAD */
 149 #define TLS_DH_anon_WITH_AES_128_GCM_SHA256     0x00A6  /* RFC 5288 */
 150 #define TLS_DH_anon_WITH_AES_256_GCM_SHA384     0x00A7  /* RFC 5288 */
 151 #define TLS_PSK_WITH_AES_128_CBC_SHA256         0x00AE  /* 174 */
 152 #define TLS_PSK_WITH_AES_256_CBC_SHA384         0x00AF  /* 175 */
 153 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA     0xC004  /* 49156 */
 154 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA     0xC005  /* 49157 */
 155 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA    0xC009  /*TLSv1   Kx=ECDH  Au=ECDSA Enc=AES(128) Mac=SHA1 */
 156 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA    0xC00A  /*TLSv1   Kx=ECDH  Au=ECDSA Enc=AES(256) Mac=SHA1 */
 157 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA       0xC00E  /* 49166 */
 158 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA       0xC00F  /* 49167 */
 159 #define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA     0xC012  /* 49170 */
 160 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA      0xC013  /*TLSv1   Kx=ECDH  Au=RSA   Enc=AES(128) Mac=SHA1 */
 161 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA      0xC014  /*TLSv1   Kx=ECDH  Au=RSA   Enc=AES(256) Mac=SHA1 */
 162 #define TLS_ECDH_anon_WITH_AES_128_CBC_SHA      0xC018  /* RFC 4492 */
 163 #define TLS_ECDH_anon_WITH_AES_256_CBC_SHA      0xC019  /* RFC 4492 */
 164 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 0xC023  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AES(128) Mac=SHA256 */
 165 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AES(256) Mac=SHA384 */
 166 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256  0xC025  /* 49189 */
 167 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384  0xC026  /* 49190 */
 168 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256   0xC027  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AES(128) Mac=SHA256 */
 169 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384   0xC028  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AES(256) Mac=SHA384 */
 170 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256    0xC029  /* 49193 */
 171 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384    0xC02A  /* 49194 */
 172 /* RFC 5288 "AES Galois Counter Mode (GCM) Cipher Suites for TLS" */
 173 #define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESGCM(128) Mac=AEAD */
 174 #define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESGCM(256) Mac=AEAD */
 175 #define TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256  0xC02D  /* 49197 */
 176 #define TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384  0xC02E  /* 49198 */
 177 #define TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256   0xC02F  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AESGCM(128) Mac=AEAD */
 178 #define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384   0xC030  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AESGCM(256) Mac=AEAD */
 179 #define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256    0xC031  /* 49201 */
 180 #define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384    0xC032  /* 49202 */
 181 #define TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA      0xC035
 182 #define TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA      0xC036
 183 #define TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256   0xC037
 184 #define TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384   0xC038
 185
 186 /* From http://wiki.mozilla.org/Security/Server_Side_TLS */
 187 /* and 'openssl ciphers -V -stdname' */
 188 #define TLS_RSA_WITH_AES_128_CCM                      0xC09C /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM(128) Mac=AEAD */
 189 #define TLS_RSA_WITH_AES_256_CCM                      0xC09D /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM(256) Mac=AEAD */
 190 #define TLS_DHE_RSA_WITH_AES_128_CCM                  0xC09E /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM(128) Mac=AEAD */
 191 #define TLS_DHE_RSA_WITH_AES_256_CCM                  0xC09F /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM(256) Mac=AEAD */
 192 #define TLS_RSA_WITH_AES_128_CCM_8                    0xC0A0 /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM8(128) Mac=AEAD */
 193 #define TLS_RSA_WITH_AES_256_CCM_8                    0xC0A1 /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM8(256) Mac=AEAD */
 194 #define TLS_DHE_RSA_WITH_AES_128_CCM_8                0xC0A2 /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM8(128) Mac=AEAD */
 195 #define TLS_DHE_RSA_WITH_AES_256_CCM_8                0xC0A3 /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM8(256) Mac=AEAD */
 196 #define TLS_ECDHE_ECDSA_WITH_AES_128_CCM              0xC0AC /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM(128) Mac=AEAD */
 197 #define TLS_ECDHE_ECDSA_WITH_AES_256_CCM              0xC0AD /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM(256) Mac=AEAD */
 198 #define TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8            0xC0AE /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM8(128) Mac=AEAD */
 199 #define TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8            0xC0AF /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM8(256) Mac=AEAD */
 200 #define TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   0xCCA8 /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 201 #define TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 0xCCA9 /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 202 #define TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256     0xCCAA /*TLSv1.2 Kx=DH    Au=RSA   Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 203
 204 #define TLS_AES_128_GCM_SHA256                        0x1301 /*TLSv1.3 Kx=any   Au=any   Enc=AESGCM(128) Mac=AEAD */
 205 #define TLS_AES_256_GCM_SHA384                        0x1302 /*TLSv1.3 Kx=any   Au=any   Enc=AESGCM(256) Mac=AEAD */
 206 #define TLS_CHACHA20_POLY1305_SHA256                  0x1303 /*TLSv1.3 Kx=any   Au=any   Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 207 #define TLS_AES_128_CCM_SHA256                        0x1304 /*TLSv1.3 Kx=any   Au=any   Enc=AESCCM(128) Mac=AEAD */
 208
 209 /* Might go to libbb.h */
 210 #define TLS_MAX_CRYPTBLOCK_SIZE 16
 211 #define TLS_MAX_OUTBUF          (1 << 14)
 212
 213 enum {
 214         SHA_INSIZE     = 64,
 215         SHA1_OUTSIZE   = 20,
 216         SHA256_OUTSIZE = 32,
 217
 218         AES128_KEYSIZE = 16,
 219         AES256_KEYSIZE = 32,
 220
 221         RSA_PREMASTER_SIZE = 48,
 222
 223         RECHDR_LEN = 5,
 224
 225         /* 8 = 3+5. 3 extra bytes result in record data being 32-bit aligned */
 226         OUTBUF_PFX = 8 + AES_BLOCK_SIZE, /* header + IV */
 227         OUTBUF_SFX = TLS_MAX_MAC_SIZE + TLS_MAX_CRYPTBLOCK_SIZE, /* MAC + padding */
 228
 229         // RFC 5246:
 230         // | 6.2.1. Fragmentation
 231         // |  The record layer fragments information blocks into TLSPlaintext
 232         // |  records carrying data in chunks of 2^14 bytes or less.  Client
 233         // |  message boundaries are not preserved in the record layer (i.e.,
 234         // |  multiple client messages of the same ContentType MAY be coalesced
 235         // |  into a single TLSPlaintext record, or a single message MAY be
 236         // |  fragmented across several records)
 237         // |...
 238         // |  length
 239         // |    The length (in bytes) of the following TLSPlaintext.fragment.
 240         // |    The length MUST NOT exceed 2^14.
 241         // |...
 242         // | 6.2.2. Record Compression and Decompression
 243         // |...
 244         // |  Compression must be lossless and may not increase the content length
 245         // |  by more than 1024 bytes.  If the decompression function encounters a
 246         // |  TLSCompressed.fragment that would decompress to a length in excess of
 247         // |  2^14 bytes, it MUST report a fatal decompression failure error.
 248         // |...
 249         // |  length
 250         // |    The length (in bytes) of the following TLSCompressed.fragment.
 251         // |    The length MUST NOT exceed 2^14 + 1024.
 252         // |...
 253         // | 6.2.3.  Record Payload Protection
 254         // |  The encryption and MAC functions translate a TLSCompressed
 255         // |  structure into a TLSCiphertext.  The decryption functions reverse
 256         // |  the process.  The MAC of the record also includes a sequence
 257         // |  number so that missing, extra, or repeated messages are
 258         // |  detectable.
 259         // |...
 260         // |  length
 261         // |    The length (in bytes) of the following TLSCiphertext.fragment.
 262         // |    The length MUST NOT exceed 2^14 + 2048.
 263         MAX_INBUF = RECHDR_LEN + (1 << 14) + 2048,
 264
 265         /* Bits for tls->flags */
 266         NEED_EC_KEY            = 1 << 0,
 267         GOT_CERT_RSA_KEY_ALG   = 1 << 1,
 268         GOT_CERT_ECDSA_KEY_ALG = 1 << 2, // so far unused
 269         GOT_EC_KEY             = 1 << 3,
 270         ENCRYPTION_AESGCM      = 1 << 4, // else AES-SHA (or NULL-SHA if ALLOW_RSA_NULL_SHA256=1)
 271         ENCRYPT_ON_WRITE       = 1 << 5,
 272 };
 273
 274 struct record_hdr {
 275         uint8_t type;
 276         uint8_t proto_maj, proto_min;
 277         uint8_t len16_hi, len16_lo;
 278 };
 279
 280 struct tls_handshake_data {
 281         /* In bbox, md5/sha1/sha256 ctx's are the same structure */
 282         md5sha_ctx_t handshake_hash_ctx;
 283
 284         uint8_t client_and_server_rand32[2 * 32];
 285         uint8_t master_secret[48];
 286
 287 //TODO: store just the DER key here, parse/use/delete it when sending client key
 288 //this way it will stay key type agnostic here.
 289         psRsaKey_t server_rsa_pub_key;
 290         uint8_t ecc_pub_key32[32];
 291
 292 /* HANDSHAKE HASH: */
 293         //unsigned saved_client_hello_size;
 294         //uint8_t saved_client_hello[1];
 295 };
 296
 297
 298 static unsigned get24be(const uint8_t *p)
 299 {
 300         return 0x100*(0x100*p[0] + p[1]) + p[2];
 301 }
 302
 303 #if TLS_DEBUG
 304 /* Nondestructively see the current hash value */
 305 # if TLS_DEBUG_HASH
 306 static unsigned sha_peek(md5sha_ctx_t *ctx, void *buffer)
 307 {
 308         md5sha_ctx_t ctx_copy = *ctx; /* struct copy */
 309         return sha_end(&ctx_copy, buffer);
 310 }
 311 # endif
 312
 313 static void dump_hex(const char *fmt, const void *vp, int len)
 314 {
 315         char hexbuf[32 * 1024 + 4];
 316         const uint8_t *p = vp;
 317
 318         bin2hex(hexbuf, (void*)p, len)[0] = '\0';
 319         dbg(fmt, hexbuf);
 320 }
 321
 322 static void dump_tls_record(const void *vp, int len)
 323 {
 324         const uint8_t *p = vp;
 325
 326         while (len > 0) {
 327                 unsigned xhdr_len;
 328                 if (len < RECHDR_LEN) {
 329                         dump_hex("< |%s|\n", p, len);
 330                         return;
 331                 }
 332                 xhdr_len = 0x100*p[3] + p[4];
 333                 dbg("< hdr_type:%u ver:%u.%u len:%u", p[0], p[1], p[2], xhdr_len);
 334                 p += RECHDR_LEN;
 335                 len -= RECHDR_LEN;
 336                 if (len >= 4 && p[-RECHDR_LEN] == RECORD_TYPE_HANDSHAKE) {
 337                         unsigned len24 = get24be(p + 1);
 338                         dbg(" type:%u len24:%u", p[0], len24);
 339                 }
 340                 if (xhdr_len > len)
 341                         xhdr_len = len;
 342                 dump_hex(" |%s|\n", p, xhdr_len);
 343                 p += xhdr_len;
 344                 len -= xhdr_len;
 345         }
 346 }
 347 #else
 348 # define dump_hex(...) ((void)0)
 349 # define dump_tls_record(...) ((void)0)
 350 #endif
 351
 352 void FAST_FUNC tls_get_random(void *buf, unsigned len)
 353 {
 354         if (len != open_read_close("/dev/urandom", buf, len))
 355                 xfunc_die();
 356 }
 357
 358 static void xorbuf3(void *dst, const void *src1, const void *src2, unsigned count)
 359 {
 360         uint8_t *d = dst;
 361         const uint8_t *s1 = src1;
 362         const uint8_t* s2 = src2;
 363         while (count--)
 364                 *d++ = *s1++ ^ *s2++;
 365 }
 366
 367 void FAST_FUNC xorbuf(void *dst, const void *src, unsigned count)
 368 {
 369         xorbuf3(dst, dst, src, count);
 370 }
 371
 372 void FAST_FUNC xorbuf_aligned_AES_BLOCK_SIZE(void *dst, const void *src)
 373 {
 374         unsigned long *d = dst;
 375         const unsigned long *s = src;
 376         d[0] ^= s[0];
 377 #if ULONG_MAX <= 0xffffffffffffffff
 378         d[1] ^= s[1];
 379  #if ULONG_MAX == 0xffffffff
 380         d[2] ^= s[2];
 381         d[3] ^= s[3];
 382  #endif
 383 #endif
 384 }
 385
 386 #if !TLS_DEBUG_HASH
 387 # define hash_handshake(tls, fmt, buffer, len) \
 388          hash_handshake(tls, buffer, len)
 389 #endif
 390 static void hash_handshake(tls_state_t *tls, const char *fmt, const void *buffer, unsigned len)
 391 {
 392         md5sha_hash(&tls->hsd->handshake_hash_ctx, buffer, len);
 393 #if TLS_DEBUG_HASH
 394         {
 395                 uint8_t h[TLS_MAX_MAC_SIZE];
 396                 dump_hex(fmt, buffer, len);
 397                 dbg(" (%u bytes) ", (int)len);
 398                 len = sha_peek(&tls->hsd->handshake_hash_ctx, h);
 399                 if (ENABLE_FEATURE_TLS_SHA1 && len == SHA1_OUTSIZE)
 400                         dump_hex("sha1:%s\n", h, len);
 401                 else
 402                 if (len == SHA256_OUTSIZE)
 403                         dump_hex("sha256:%s\n", h, len);
 404                 else
 405                         dump_hex("sha???:%s\n", h, len);
 406         }
 407 #endif
 408 }
 409
 410 #if !ENABLE_FEATURE_TLS_SHA1
 411 # define TLS_MAC_SIZE(tls) SHA256_OUTSIZE
 412 #else
 413 # define TLS_MAC_SIZE(tls) (tls)->MAC_size
 414 #endif
 415
 416 // RFC 2104:
 417 // HMAC(key, text) based on a hash H (say, sha256) is:
 418 // ipad = [0x36 x INSIZE]
 419 // opad = [0x5c x INSIZE]
 420 // HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text))
 421 //
 422 // H(key XOR opad) and H(key XOR ipad) can be precomputed
 423 // if we often need HMAC hmac with the same key.
 424 //
 425 // text is often given in disjoint pieces.
 426 typedef struct hmac_precomputed {
 427         md5sha_ctx_t hashed_key_xor_ipad;
 428         md5sha_ctx_t hashed_key_xor_opad;
 429 } hmac_precomputed_t;
 430
 431 typedef void md5sha_begin_func(md5sha_ctx_t *ctx) FAST_FUNC;
 432 #if !ENABLE_FEATURE_TLS_SHA1
 433 #define hmac_begin(pre,key,key_size,begin) \
 434         hmac_begin(pre,key,key_size)
 435 #define begin sha256_begin
 436 #endif
 437 static void hmac_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size, md5sha_begin_func *begin)
 438 {
 439         uint8_t key_xor_ipad[SHA_INSIZE];
 440         uint8_t key_xor_opad[SHA_INSIZE];
 441 //      uint8_t tempkey[SHA1_OUTSIZE < SHA256_OUTSIZE ? SHA256_OUTSIZE : SHA1_OUTSIZE];
 442         unsigned i;
 443
 444         // "The authentication key can be of any length up to INSIZE, the
 445         // block length of the hash function.  Applications that use keys longer
 446         // than INSIZE bytes will first hash the key using H and then use the
 447         // resultant OUTSIZE byte string as the actual key to HMAC."
 448         if (key_size > SHA_INSIZE) {
 449                 bb_simple_error_msg_and_die("HMAC key>64"); //does not happen (yet?)
 450 //              md5sha_ctx_t ctx;
 451 //              begin(&ctx);
 452 //              md5sha_hash(&ctx, key, key_size);
 453 //              key_size = sha_end(&ctx, tempkey);
 454 //              //key = tempkey; - right? RIGHT? why does it work without this?
 455 //              // because SHA_INSIZE is 64, but hmac() is always called with
 456 //              // key_size = tls->MAC_size = SHA1/256_OUTSIZE (20 or 32),
 457 //              // and prf_hmac_sha256() -> hmac_sha256() key sizes are:
 458 //              // - RSA_PREMASTER_SIZE is 48
 459 //              // - CURVE25519_KEYSIZE is 32
 460 //              // - master_secret[] is 48
 461         }
 462
 463         for (i = 0; i < key_size; i++) {
 464                 key_xor_ipad[i] = key[i] ^ 0x36;
 465                 key_xor_opad[i] = key[i] ^ 0x5c;
 466         }
 467         for (; i < SHA_INSIZE; i++) {
 468                 key_xor_ipad[i] = 0x36;
 469                 key_xor_opad[i] = 0x5c;
 470         }
 471
 472         begin(&pre->hashed_key_xor_ipad);
 473         begin(&pre->hashed_key_xor_opad);
 474         md5sha_hash(&pre->hashed_key_xor_ipad, key_xor_ipad, SHA_INSIZE);
 475         md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
 476 }
 477 #undef begin
 478
 479 static unsigned hmac_sha_precomputed_v(
 480                 hmac_precomputed_t *pre,
 481                 uint8_t *out,
 482                 va_list va)
 483 {
 484         uint8_t *text;
 485         unsigned len;
 486
 487         /* pre->hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
 488         /* pre->hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
 489
 490         /* calculate out = H((key XOR ipad) + text) */
 491         while ((text = va_arg(va, uint8_t*)) != NULL) {
 492                 unsigned text_size = va_arg(va, unsigned);
 493                 md5sha_hash(&pre->hashed_key_xor_ipad, text, text_size);
 494         }
 495         len = sha_end(&pre->hashed_key_xor_ipad, out);
 496
 497         /* out = H((key XOR opad) + out) */
 498         md5sha_hash(&pre->hashed_key_xor_opad, out, len);
 499         return sha_end(&pre->hashed_key_xor_opad, out);
 500 }
 501
 502 static unsigned hmac_sha_precomputed(hmac_precomputed_t *pre_init, uint8_t *out, ...)
 503 {
 504         hmac_precomputed_t pre;
 505         va_list va;
 506         unsigned len;
 507
 508         va_start(va, out);
 509         pre = *pre_init; /* struct copy */
 510         len = hmac_sha_precomputed_v(&pre, out, va);
 511         va_end(va);
 512         return len;
 513 }
 514
 515 #if !ENABLE_FEATURE_TLS_SHA1
 516 #define hmac(tls,out,key,key_size,...) \
 517         hmac(out,key,key_size, __VA_ARGS__)
 518 #endif
 519 static unsigned hmac(tls_state_t *tls, uint8_t *out, uint8_t *key, unsigned key_size, ...)
 520 {
 521         hmac_precomputed_t pre;
 522         va_list va;
 523         unsigned len;
 524
 525         va_start(va, key_size);
 526
 527         hmac_begin(&pre, key, key_size,
 528                         (ENABLE_FEATURE_TLS_SHA1 && tls->MAC_size == SHA1_OUTSIZE)
 529                                 ? sha1_begin
 530                                 : sha256_begin
 531         );
 532         len = hmac_sha_precomputed_v(&pre, out, va);
 533
 534         va_end(va);
 535         return len;
 536 }
 537
 538 // RFC 5246:
 539 // 5.  HMAC and the Pseudorandom Function
 540 //...
 541 // In this section, we define one PRF, based on HMAC.  This PRF with the
 542 // SHA-256 hash function is used for all cipher suites defined in this
 543 // document and in TLS documents published prior to this document when
 544 // TLS 1.2 is negotiated.
 545 // ^^^^^^^^^^^^^ IMPORTANT!
 546 //               PRF uses sha256 regardless of cipher for all ciphers
 547 //               defined by RFC 5246. It's not sha1 for AES_128_CBC_SHA!
 548 //               However, for _SHA384 ciphers, it's sha384. See RFC 5288,5289.
 549 //...
 550 //    P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
 551 //                           HMAC_hash(secret, A(2) + seed) +
 552 //                           HMAC_hash(secret, A(3) + seed) + ...
 553 // where + indicates concatenation.
 554 // A() is defined as:
 555 //    A(0) = seed
 556 //    A(1) = HMAC_hash(secret, A(0)) = HMAC_hash(secret, seed)
 557 //    A(i) = HMAC_hash(secret, A(i-1))
 558 // P_hash can be iterated as many times as necessary to produce the
 559 // required quantity of data.  For example, if P_SHA256 is being used to
 560 // create 80 bytes of data, it will have to be iterated three times
 561 // (through A(3)), creating 96 bytes of output data; the last 16 bytes
 562 // of the final iteration will then be discarded, leaving 80 bytes of
 563 // output data.
 564 //
 565 // TLS's PRF is created by applying P_hash to the secret as:
 566 //
 567 //    PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 568 //
 569 // The label is an ASCII string.
 570 //
 571 // RFC 5288:
 572 // For cipher suites ending with _SHA256, the PRF is the TLS PRF
 573 // with SHA-256 as the hash function.
 574 // For cipher suites ending with _SHA384, the PRF is the TLS PRF
 575 // with SHA-384 as the hash function.
 576 static void prf_hmac_sha256(/*tls_state_t *tls,*/
 577                 uint8_t *outbuf, unsigned outbuf_size,
 578                 uint8_t *secret, unsigned secret_size,
 579                 const char *label,
 580                 uint8_t *seed, unsigned seed_size)
 581 {
 582         hmac_precomputed_t pre;
 583         uint8_t a[TLS_MAX_MAC_SIZE];
 584         uint8_t *out_p = outbuf;
 585         unsigned label_size = strlen(label);
 586         unsigned MAC_size = SHA256_OUTSIZE;
 587
 588         /* In P_hash() calculation, "seed" is "label + seed": */
 589 #define SEED   label, label_size, seed, seed_size
 590 #define A      a, MAC_size
 591
 592         hmac_begin(&pre, secret, secret_size, sha256_begin);
 593
 594         /* A(1) = HMAC_hash(secret, seed) */
 595         hmac_sha_precomputed(&pre, a, SEED, NULL);
 596
 597         for (;;) {
 598                 /* HMAC_hash(secret, A(1) + seed) */
 599                 if (outbuf_size <= MAC_size) {
 600                         /* Last, possibly incomplete, block */
 601                         /* (use a[] as temp buffer) */
 602                         hmac_sha_precomputed(&pre, a, A, SEED, NULL);
 603                         memcpy(out_p, a, outbuf_size);
 604                         return;
 605                 }
 606                 /* Not last block. Store directly to result buffer */
 607                 hmac_sha_precomputed(&pre, out_p, A, SEED, NULL);
 608                 out_p += MAC_size;
 609                 outbuf_size -= MAC_size;
 610                 /* A(2) = HMAC_hash(secret, A(1)) */
 611                 hmac_sha_precomputed(&pre, a, A, NULL);
 612         }
 613 #undef A
 614 #undef SECRET
 615 #undef SEED
 616 }
 617
 618 static void bad_record_die(tls_state_t *tls, const char *expected, int len)
 619 {
 620         bb_error_msg("got bad TLS record (len:%d) while expecting %s", len, expected);
 621         if (len > 0) {
 622                 uint8_t *p = tls->inbuf;
 623                 if (len > 99)
 624                         len = 99; /* don't flood, a few lines should be enough */
 625                 do {
 626                         fprintf(stderr, " %02x", *p++);
 627                         len--;
 628                 } while (len != 0);
 629                 fputc('\n', stderr);
 630         }
 631         xfunc_die();
 632 }
 633
 634 static void tls_error_die(tls_state_t *tls, int line)
 635 {
 636         dump_tls_record(tls->inbuf, tls->ofs_to_buffered + tls->buffered_size);
 637         bb_error_msg_and_die("tls error at line %d cipher:%04x", line, tls->cipher_id);
 638 }
 639 #define tls_error_die(tls) tls_error_die(tls, __LINE__)
 640
 641 #if 0 //UNUSED
 642 static void tls_free_inbuf(tls_state_t *tls)
 643 {
 644         if (tls->buffered_size == 0) {
 645                 free(tls->inbuf);
 646                 tls->inbuf_size = 0;
 647                 tls->inbuf = NULL;
 648         }
 649 }
 650 #endif
 651
 652 static void tls_free_outbuf(tls_state_t *tls)
 653 {
 654         free(tls->outbuf);
 655         tls->outbuf_size = 0;
 656         tls->outbuf = NULL;
 657 }
 658
 659 static void *tls_get_outbuf(tls_state_t *tls, int len)
 660 {
 661         if (len > TLS_MAX_OUTBUF)
 662                 xfunc_die();
 663         len += OUTBUF_PFX + OUTBUF_SFX;
 664         if (tls->outbuf_size < len) {
 665                 tls->outbuf_size = len;
 666                 tls->outbuf = xrealloc(tls->outbuf, len);
 667         }
 668         return tls->outbuf + OUTBUF_PFX;
 669 }
 670
 671 static void *tls_get_zeroed_outbuf(tls_state_t *tls, int len)
 672 {
 673         void *record = tls_get_outbuf(tls, len);
 674         memset(record, 0, len);
 675         return record;
 676 }
 677
 678 static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, unsigned type)
 679 {
 680         uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 681         struct record_hdr *xhdr;
 682         uint8_t padding_length;
 683
 684         xhdr = (void*)(buf - RECHDR_LEN);
 685         if (!ALLOW_RSA_NULL_SHA256 /* if "no encryption" can't be selected */
 686          || tls->cipher_id != TLS_RSA_WITH_NULL_SHA256 /* or if it wasn't selected */
 687         ) {
 688                 xhdr = (void*)(buf - RECHDR_LEN - AES_BLOCK_SIZE); /* place for IV */
 689         }
 690
 691         xhdr->type = type;
 692         xhdr->proto_maj = TLS_MAJ;
 693         xhdr->proto_min = TLS_MIN;
 694         /* fake unencrypted record len for MAC calculation */
 695         xhdr->len16_hi = size >> 8;
 696         xhdr->len16_lo = size & 0xff;
 697
 698         /* Calculate MAC signature */
 699         hmac(tls, buf + size, /* result */
 700                 tls->client_write_MAC_key, TLS_MAC_SIZE(tls),
 701                 &tls->write_seq64_be, sizeof(tls->write_seq64_be),
 702                 xhdr, RECHDR_LEN,
 703                 buf, size,
 704                 NULL
 705         );
 706         tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
 707
 708         size += TLS_MAC_SIZE(tls);
 709
 710         // RFC 5246:
 711         // 6.2.3.1.  Null or Standard Stream Cipher
 712         //
 713         // Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6)
 714         // convert TLSCompressed.fragment structures to and from stream
 715         // TLSCiphertext.fragment structures.
 716         //
 717         //    stream-ciphered struct {
 718         //        opaque content[TLSCompressed.length];
 719         //        opaque MAC[SecurityParameters.mac_length];
 720         //    } GenericStreamCipher;
 721         //
 722         // The MAC is generated as:
 723         //    MAC(MAC_write_key, seq_num +
 724         //                          TLSCompressed.type +
 725         //                          TLSCompressed.version +
 726         //                          TLSCompressed.length +
 727         //                          TLSCompressed.fragment);
 728         // where "+" denotes concatenation.
 729         // seq_num
 730         //    The sequence number for this record.
 731         // MAC
 732         //    The MAC algorithm specified by SecurityParameters.mac_algorithm.
 733         //
 734         // Note that the MAC is computed before encryption.  The stream cipher
 735         // encrypts the entire block, including the MAC.
 736         //...
 737         // Appendix C.  Cipher Suite Definitions
 738         //...
 739         // MAC       Algorithm    mac_length  mac_key_length
 740         // --------  -----------  ----------  --------------
 741         // SHA       HMAC-SHA1       20            20
 742         // SHA256    HMAC-SHA256     32            32
 743         if (ALLOW_RSA_NULL_SHA256
 744          && tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
 745         ) {
 746                 /* No encryption, only signing */
 747                 xhdr->len16_hi = size >> 8;
 748                 xhdr->len16_lo = size & 0xff;
 749                 dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 750                 xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 751                 dbg("wrote %u bytes (NULL crypt, SHA256 hash)\n", size);
 752                 return;
 753         }
 754
 755         // 6.2.3.2.  CBC Block Cipher
 756         // For block ciphers (such as 3DES or AES), the encryption and MAC
 757         // functions convert TLSCompressed.fragment structures to and from block
 758         // TLSCiphertext.fragment structures.
 759         //    struct {
 760         //        opaque IV[SecurityParameters.record_iv_length];
 761         //        block-ciphered struct {
 762         //            opaque content[TLSCompressed.length];
 763         //            opaque MAC[SecurityParameters.mac_length];
 764         //            uint8 padding[GenericBlockCipher.padding_length];
 765         //            uint8 padding_length;
 766         //        };
 767         //    } GenericBlockCipher;
 768         //...
 769         // IV
 770         //    The Initialization Vector (IV) SHOULD be chosen at random, and
 771         //    MUST be unpredictable.  Note that in versions of TLS prior to 1.1,
 772         //    there was no IV field (...).  For block ciphers, the IV length is
 773         //    of length SecurityParameters.record_iv_length, which is equal to the
 774         //    SecurityParameters.block_size.
 775         // padding
 776         //    Padding that is added to force the length of the plaintext to be
 777         //    an integral multiple of the block cipher's block length.
 778         // padding_length
 779         //    The padding length MUST be such that the total size of the
 780         //    GenericBlockCipher structure is a multiple of the cipher's block
 781         //    length.  Legal values range from zero to 255, inclusive.
 782         //...
 783         // Appendix C.  Cipher Suite Definitions
 784         //...
 785         //                         Key      IV   Block
 786         // Cipher        Type    Material  Size  Size
 787         // ------------  ------  --------  ----  -----
 788         // AES_128_CBC   Block      16      16     16
 789         // AES_256_CBC   Block      32      16     16
 790
 791         tls_get_random(buf - AES_BLOCK_SIZE, AES_BLOCK_SIZE); /* IV */
 792         dbg("before crypt: 5 hdr + %u data + %u hash bytes\n",
 793                         size - TLS_MAC_SIZE(tls), TLS_MAC_SIZE(tls));
 794
 795         /* Fill IV and padding in outbuf */
 796         // RFC is talking nonsense:
 797         //    "Padding that is added to force the length of the plaintext to be
 798         //    an integral multiple of the block cipher's block length."
 799         // WRONG. _padding+padding_length_, not just _padding_,
 800         // pads the data.
 801         // IOW: padding_length is the last byte of padding[] array,
 802         // contrary to what RFC depicts.
 803         //
 804         // What actually happens is that there is always padding.
 805         // If you need one byte to reach BLOCKSIZE, this byte is 0x00.
 806         // If you need two bytes, they are both 0x01.
 807         // If you need three, they are 0x02,0x02,0x02. And so on.
 808         // If you need no bytes to reach BLOCKSIZE, you have to pad a full
 809         // BLOCKSIZE with bytes of value (BLOCKSIZE-1).
 810         // It's ok to have more than minimum padding, but we do minimum.
 811         padding_length = (~size) & (AES_BLOCK_SIZE - 1);
 812         do {
 813                 buf[size++] = padding_length; /* padding */
 814         } while ((size & (AES_BLOCK_SIZE - 1)) != 0);
 815
 816         /* Encrypt content+MAC+padding in place */
 817         aes_cbc_encrypt(
 818                 &tls->aes_encrypt, /* selects 128/256 */
 819                 buf - AES_BLOCK_SIZE, /* IV */
 820                 buf, size, /* plaintext */
 821                 buf /* ciphertext */
 822         );
 823
 824         /* Write out */
 825         dbg("writing 5 + %u IV + %u encrypted bytes, padding_length:0x%02x\n",
 826                         AES_BLOCK_SIZE, size, padding_length);
 827         size += AES_BLOCK_SIZE;     /* + IV */
 828         xhdr->len16_hi = size >> 8;
 829         xhdr->len16_lo = size & 0xff;
 830         dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 831         xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 832         dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 833 }
 834
 835 /* Example how GCM encryption combines nonce, aad, input and generates
 836  * "header | exp_nonce | encrypted output | tag":
 837  * nonce:0d 6a 26 31 00 00 00 00 00 00 00 01 (implicit 4 bytes (derived from master secret), then explicit 8 bytes)
 838  * aad:  00 00 00 00 00 00 00 01 17 03 03 00 1c
 839  * in:   47 45 54 20 2f 69 6e 64 65 78 2e 68 74 6d 6c 20 48 54 54 50 2f 31 2e 30 0d 0a 0d 0a "GET /index.html HTTP/1.0\r\n\r\n" (0x1c bytes)
 840  * out:  f7 8a b2 8f 78 0e f6 d5 76 17 2e b5 6d 46 59 56 8b 46 9f 0b d9 2c 35 28 13 66 19 be
 841  * tag:  c2 86 ce 4a 50 4a d0 aa 50 b3 76 5c 49 2a 3f 33
 842  * sent: 17 03 03 00 34|00 00 00 00 00 00 00 01|f7 8a b2 8f 78 0e f6 d5 76 17 2e b5 6d 46 59 56 8b 46 9f 0b d9 2c 35 28 13 66 19 be|c2 86 ce 4a 50 4a d0 aa 50 b3 76 5c 49 2a 3f 33
 843  * .............................................^^ buf points here
 844  */
 845 static void xwrite_encrypted_aesgcm(tls_state_t *tls, unsigned size, unsigned type)
 846 {
 847 #define COUNTER(v) (*(uint32_t*)(v + 12))
 848
 849         uint8_t aad[13 + 3] ALIGNED_long;   /* +3 creates [16] buffer, simplifying GHASH() */
 850         uint8_t nonce[12 + 4] ALIGNED_long; /* +4 creates space for AES block counter */
 851         uint8_t scratch[AES_BLOCK_SIZE] ALIGNED_long; //[16]
 852         uint8_t authtag[AES_BLOCK_SIZE] ALIGNED_long; //[16]
 853         uint8_t *buf;
 854         struct record_hdr *xhdr;
 855         unsigned remaining;
 856         unsigned cnt;
 857         uint64_t t64;
 858
 859         buf = tls->outbuf + OUTBUF_PFX; /* see above for the byte it points to */
 860         dump_hex("xwrite_encrypted_aesgcm plaintext:%s\n", buf, size);
 861
 862         xhdr = (void*)(buf - 8 - RECHDR_LEN);
 863         xhdr->type = type; /* do it here so that "type" param no longer used */
 864
 865         aad[8] = type;
 866         aad[9] = TLS_MAJ;
 867         aad[10] = TLS_MIN;
 868         aad[11] = size >> 8;
 869         /* set aad[12], and clear aad[13..15] */
 870         COUNTER(aad) = SWAP_LE32(size & 0xff);
 871
 872         memcpy(nonce, tls->client_write_IV, 4);
 873         t64 = tls->write_seq64_be;
 874         move_to_unaligned64(nonce + 4, t64);
 875         move_to_unaligned64(aad,       t64);
 876         move_to_unaligned64(buf - 8,   t64);
 877         /* seq64 is not used later in this func, can increment here */
 878         tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(t64));
 879
 880         cnt = 1;
 881         remaining = size;
 882         while (remaining != 0) {
 883                 unsigned n;
 884
 885                 cnt++;
 886                 COUNTER(nonce) = htonl(cnt); /* yes, first cnt here is 2 (!) */
 887                 aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
 888                 n = remaining > AES_BLOCK_SIZE ? AES_BLOCK_SIZE : remaining;
 889                 xorbuf(buf, scratch, n);
 890                 buf += n;
 891                 remaining -= n;
 892         }
 893
 894         aesgcm_GHASH(tls->H, aad, /*sizeof(aad),*/ tls->outbuf + OUTBUF_PFX, size, authtag /*, sizeof(authtag)*/);
 895         COUNTER(nonce) = htonl(1);
 896         aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
 897         xorbuf_aligned_AES_BLOCK_SIZE(authtag, scratch);
 898
 899         memcpy(buf, authtag, sizeof(authtag));
 900
 901         /* Write out */
 902         xhdr = (void*)(tls->outbuf + OUTBUF_PFX - 8 - RECHDR_LEN);
 903         size += 8 + sizeof(authtag);
 904         /*xhdr->type = type; - already is */
 905         xhdr->proto_maj = TLS_MAJ;
 906         xhdr->proto_min = TLS_MIN;
 907         xhdr->len16_hi = size >> 8;
 908         xhdr->len16_lo = size & 0xff;
 909         size += RECHDR_LEN;
 910         dump_raw_out(">> %s\n", xhdr, size);
 911         xwrite(tls->ofd, xhdr, size);
 912         dbg("wrote %u bytes\n", size);
 913 #undef COUNTER
 914 }
 915
 916 static void xwrite_encrypted(tls_state_t *tls, unsigned size, unsigned type)
 917 {
 918         if (!(tls->flags & ENCRYPTION_AESGCM)) {
 919                 xwrite_encrypted_and_hmac_signed(tls, size, type);
 920                 return;
 921         }
 922         xwrite_encrypted_aesgcm(tls, size, type);
 923 }
 924
 925 static void xwrite_handshake_record(tls_state_t *tls, unsigned size)
 926 {
 927         uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 928         struct record_hdr *xhdr = (void*)(buf - RECHDR_LEN);
 929
 930         xhdr->type = RECORD_TYPE_HANDSHAKE;
 931         xhdr->proto_maj = TLS_MAJ;
 932         xhdr->proto_min = TLS_MIN;
 933         xhdr->len16_hi = size >> 8;
 934         xhdr->len16_lo = size & 0xff;
 935         dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 936         xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 937         dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 938 }
 939
 940 static void xwrite_and_update_handshake_hash(tls_state_t *tls, unsigned size)
 941 {
 942         if (!(tls->flags & ENCRYPT_ON_WRITE)) {
 943                 uint8_t *buf;
 944
 945                 xwrite_handshake_record(tls, size);
 946                 /* Handshake hash does not include record headers */
 947                 buf = tls->outbuf + OUTBUF_PFX;
 948                 hash_handshake(tls, ">> hash:%s", buf, size);
 949                 return;
 950         }
 951         xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
 952 }
 953
 954 static int tls_has_buffered_record(tls_state_t *tls)
 955 {
 956         int buffered = tls->buffered_size;
 957         struct record_hdr *xhdr;
 958         int rec_size;
 959
 960         if (buffered < RECHDR_LEN)
 961                 return 0;
 962         xhdr = (void*)(tls->inbuf + tls->ofs_to_buffered);
 963         rec_size = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
 964         if (buffered < rec_size)
 965                 return 0;
 966         return rec_size;
 967 }
 968
 969 static const char *alert_text(int code)
 970 {
 971         switch (code) {
 972         case 20:  return "bad MAC";
 973         case 50:  return "decode error";
 974         case 51:  return "decrypt error";
 975         case 40:  return "handshake failure";
 976         case 112: return "unrecognized name";
 977         }
 978         return itoa(code);
 979 }
 980
 981 static void tls_aesgcm_decrypt(tls_state_t *tls, uint8_t *buf, int size)
 982 {
 983 #define COUNTER(v) (*(uint32_t*)(v + 12))
 984
 985         //uint8_t aad[13 + 3] ALIGNED_long; /* +3 creates [16] buffer, simplifying GHASH() */
 986         uint8_t nonce[12 + 4] ALIGNED_long; /* +4 creates space for AES block counter */
 987         uint8_t scratch[AES_BLOCK_SIZE] ALIGNED_long; //[16]
 988         //uint8_t authtag[AES_BLOCK_SIZE] ALIGNED_long; //[16]
 989         unsigned remaining;
 990         unsigned cnt;
 991
 992         //memcpy(aad, buf, 8);
 993         //aad[8] = type;
 994         //aad[9] = TLS_MAJ;
 995         //aad[10] = TLS_MIN;
 996         //aad[11] = size >> 8;
 997         ///* set aad[12], and clear aad[13..15] */
 998         //COUNTER(aad) = SWAP_LE32(size & 0xff);
 999
1000         memcpy(nonce,     tls->server_write_IV, 4);
1001         memcpy(nonce + 4, buf, 8);
1002
1003         cnt = 1;
1004         remaining = size;
1005         while (remaining != 0) {
1006                 unsigned n;
1007
1008                 cnt++;
1009                 COUNTER(nonce) = htonl(cnt); /* yes, first cnt here is 2 (!) */
1010                 aes_encrypt_one_block(&tls->aes_decrypt, nonce, scratch);
1011                 n = remaining > AES_BLOCK_SIZE ? AES_BLOCK_SIZE : remaining;
1012                 xorbuf3(buf, scratch, buf + 8, n);
1013                 buf += n;
1014                 remaining -= n;
1015         }
1016
1017         //aesgcm_GHASH(tls->H, aad, tls->inbuf + RECHDR_LEN, size, authtag);
1018         //COUNTER(nonce) = htonl(1);
1019         //aes_encrypt_one_block(&tls->aes_encrypt, nonce, scratch);
1020         //xorbuf_aligned_AES_BLOCK_SIZE(authtag, scratch);
1021
1022         //memcmp(buf, authtag, sizeof(authtag)) || DIE("HASH DOES NOT MATCH!");
1023 #undef COUNTER
1024 }
1025
1026 static int tls_xread_record(tls_state_t *tls, const char *expected)
1027 {
1028         struct record_hdr *xhdr;
1029         int sz;
1030         int total;
1031         int target;
1032
1033  again:
1034         dbg("ofs_to_buffered:%u buffered_size:%u\n", tls->ofs_to_buffered, tls->buffered_size);
1035         total = tls->buffered_size;
1036         if (total != 0) {
1037                 memmove(tls->inbuf, tls->inbuf + tls->ofs_to_buffered, total);
1038                 //dbg("<< remaining at %d [%d] ", tls->ofs_to_buffered, total);
1039                 //dump_raw_in("<< %s\n", tls->inbuf, total);
1040         }
1041         errno = 0;
1042         target = MAX_INBUF;
1043         for (;;) {
1044                 int rem;
1045
1046                 if (total >= RECHDR_LEN && target == MAX_INBUF) {
1047                         xhdr = (void*)tls->inbuf;
1048                         target = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
1049
1050                         if (target > MAX_INBUF /* malformed input (too long) */
1051                          || xhdr->proto_maj != TLS_MAJ
1052                          || xhdr->proto_min != TLS_MIN
1053                         ) {
1054                                 sz = total < target ? total : target;
1055                                 bad_record_die(tls, expected, sz);
1056                         }
1057                         dbg("xhdr type:%d ver:%d.%d len:%d\n",
1058                                 xhdr->type, xhdr->proto_maj, xhdr->proto_min,
1059                                 0x100 * xhdr->len16_hi + xhdr->len16_lo
1060                         );
1061                 }
1062                 /* if total >= target, we have a full packet (and possibly more)... */
1063                 if (total - target >= 0)
1064                         break;
1065                 /* input buffer is grown only as needed */
1066                 rem = tls->inbuf_size - total;
1067                 if (rem == 0) {
1068                         tls->inbuf_size += MAX_INBUF / 8;
1069                         if (tls->inbuf_size > MAX_INBUF)
1070                                 tls->inbuf_size = MAX_INBUF;
1071                         dbg("inbuf_size:%d\n", tls->inbuf_size);
1072                         rem = tls->inbuf_size - total;
1073                         tls->inbuf = xrealloc(tls->inbuf, tls->inbuf_size);
1074                 }
1075                 sz = safe_read(tls->ifd, tls->inbuf + total, rem);
1076                 if (sz <= 0) {
1077                         if (sz == 0 && total == 0) {
1078                                 /* "Abrupt" EOF, no TLS shutdown (seen from kernel.org) */
1079                                 dbg("EOF (without TLS shutdown) from peer\n");
1080                                 tls->buffered_size = 0;
1081                                 goto end;
1082                         }
1083                         bb_perror_msg_and_die("short read, have only %d", total);
1084                 }
1085                 dump_raw_in("<< %s\n", tls->inbuf + total, sz);
1086                 total += sz;
1087         }
1088         tls->buffered_size = total - target;
1089         tls->ofs_to_buffered = target;
1090         //dbg("<< stashing at %d [%d] ", tls->ofs_to_buffered, tls->buffered_size);
1091         //dump_hex("<< %s\n", tls->inbuf + tls->ofs_to_buffered, tls->buffered_size);
1092
1093         sz = target - RECHDR_LEN;
1094
1095         /* Needs to be decrypted? */
1096         if (tls->min_encrypted_len_on_read != 0) {
1097                 if (sz < (int)tls->min_encrypted_len_on_read)
1098                         bb_error_msg_and_die("bad encrypted len:%u", sz);
1099
1100                 if (tls->flags & ENCRYPTION_AESGCM) {
1101                         /* AESGCM */
1102                         uint8_t *p = tls->inbuf + RECHDR_LEN;
1103
1104                         sz -= 8 + AES_BLOCK_SIZE; /* we will overwrite nonce, drop hash */
1105                         tls_aesgcm_decrypt(tls, p, sz);
1106                         dbg("encrypted size:%u\n", sz);
1107                 } else
1108                 if (tls->min_encrypted_len_on_read > TLS_MAC_SIZE(tls)) {
1109                         /* AES+SHA */
1110                         uint8_t *p = tls->inbuf + RECHDR_LEN;
1111                         int padding_len;
1112
1113                         if (sz & (AES_BLOCK_SIZE-1))
1114                                 bb_error_msg_and_die("bad encrypted len:%u", sz);
1115
1116                         /* Decrypt content+MAC+padding, moving it over IV in the process */
1117                         sz -= AES_BLOCK_SIZE; /* we will overwrite IV now */
1118                         aes_cbc_decrypt(
1119                                 &tls->aes_decrypt, /* selects 128/256 */
1120                                 p, /* IV */
1121                                 p + AES_BLOCK_SIZE, sz, /* ciphertext */
1122                                 p /* plaintext */
1123                         );
1124                         padding_len = p[sz - 1];
1125                         dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[0], padding_len);
1126                         padding_len++;
1127                         sz -= TLS_MAC_SIZE(tls) + padding_len; /* drop MAC and padding */
1128                 } else {
1129                         /* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
1130                         /* else: no encryption yet on input, subtract zero = NOP */
1131                         sz -= tls->min_encrypted_len_on_read;
1132                 }
1133         }
1134         if (sz < 0)
1135                 bb_simple_error_msg_and_die("encrypted data too short");
1136
1137         //dump_hex("<< %s\n", tls->inbuf, RECHDR_LEN + sz);
1138
1139         xhdr = (void*)tls->inbuf;
1140         if (xhdr->type == RECORD_TYPE_ALERT && sz >= 2) {
1141                 uint8_t *p = tls->inbuf + RECHDR_LEN;
1142                 dbg("ALERT size:%d level:%d description:%d\n", sz, p[0], p[1]);
1143                 if (p[0] == 2) { /* fatal */
1144                         bb_error_msg_and_die("TLS %s from peer (alert code %d): %s",
1145                                 "error",
1146                                 p[1], alert_text(p[1])
1147                         );
1148                 }
1149                 if (p[0] == 1) { /* warning */
1150                         if (p[1] == 0) { /* "close_notify" warning: it's EOF */
1151                                 dbg("EOF (TLS encoded) from peer\n");
1152                                 sz = 0;
1153                                 goto end;
1154                         }
1155 //This possibly needs to be cached and shown only if
1156 //a fatal alert follows
1157 //                      bb_error_msg("TLS %s from peer (alert code %d): %s",
1158 //                              "warning",
1159 //                              p[1], alert_text(p[1])
1160 //                      );
1161                         /* discard it, get next record */
1162                         goto again;
1163                 }
1164                 /* p[0] not 1 or 2: not defined in protocol */
1165                 sz = 0;
1166                 goto end;
1167         }
1168
1169         /* RFC 5246 is not saying it explicitly, but sha256 hash
1170          * in our FINISHED record must include data of incoming packets too!
1171          */
1172         if (tls->inbuf[0] == RECORD_TYPE_HANDSHAKE
1173 /* HANDSHAKE HASH: */
1174         // && do_we_know_which_hash_to_use /* server_hello() might not know it in the future! */
1175         ) {
1176                 hash_handshake(tls, "<< hash:%s", tls->inbuf + RECHDR_LEN, sz);
1177         }
1178  end:
1179         dbg("got block len:%u\n", sz);
1180         return sz;
1181 }
1182
1183 static void binary_to_pstm(pstm_int *pstm_n, uint8_t *bin_ptr, unsigned len)
1184 {
1185         pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len);
1186         pstm_read_unsigned_bin(pstm_n, bin_ptr, len);
1187         //return bin_ptr + len;
1188 }
1189
1190 /*
1191  * DER parsing routines
1192  */
1193 static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end)
1194 {
1195         unsigned len, len1;
1196
1197         if (end - der < 2)
1198                 xfunc_die();
1199 //      if ((der[0] & 0x1f) == 0x1f) /* not single-byte item code? */
1200 //              xfunc_die();
1201
1202         len = der[1]; /* maybe it's short len */
1203         if (len >= 0x80) {
1204                 /* no, it's long */
1205
1206                 if (len == 0x80 || end - der < (int)(len - 0x7e)) {
1207                         /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */
1208                         /* need 3 or 4 bytes for 81, 82 */
1209                         xfunc_die();
1210                 }
1211
1212                 len1 = der[2]; /* if (len == 0x81) it's "ii 81 xx", fetch xx */
1213                 if (len > 0x82) {
1214                         /* >0x82 is "3+ bytes of len", should not happen realistically */
1215                         xfunc_die();
1216                 }
1217                 if (len == 0x82) { /* it's "ii 82 xx yy" */
1218                         len1 = 0x100*len1 + der[3];
1219                         der += 1; /* skip [yy] */
1220                 }
1221                 der += 1; /* skip [xx] */
1222                 len = len1;
1223 //              if (len < 0x80)
1224 //                      xfunc_die(); /* invalid DER: must use short len if can */
1225         }
1226         der += 2; /* skip [code]+[1byte] */
1227
1228         if (end - der < (int)len)
1229                 xfunc_die();
1230         *bodyp = der;
1231
1232         return len;
1233 }
1234
1235 static uint8_t *enter_der_item(uint8_t *der, uint8_t **endp)
1236 {
1237         uint8_t *new_der;
1238         unsigned len = get_der_len(&new_der, der, *endp);
1239         dbg_der("entered der @%p:0x%02x len:%u inner_byte @%p:0x%02x\n", der, der[0], len, new_der, new_der[0]);
1240         /* Move "end" position to cover only this item */
1241         *endp = new_der + len;
1242         return new_der;
1243 }
1244
1245 static uint8_t *skip_der_item(uint8_t *der, uint8_t *end)
1246 {
1247         uint8_t *new_der;
1248         unsigned len = get_der_len(&new_der, der, end);
1249         /* Skip body */
1250         new_der += len;
1251         dbg_der("skipped der 0x%02x, next byte 0x%02x\n", der[0], new_der[0]);
1252         return new_der;
1253 }
1254
1255 static void der_binary_to_pstm(pstm_int *pstm_n, uint8_t *der, uint8_t *end)
1256 {
1257         uint8_t *bin_ptr;
1258         unsigned len = get_der_len(&bin_ptr, der, end);
1259
1260         dbg_der("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]);
1261         binary_to_pstm(pstm_n, bin_ptr, len);
1262 }
1263
1264 static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len)
1265 {
1266 /* Certificate is a DER-encoded data structure. Each DER element has a length,
1267  * which makes it easy to skip over large compound elements of any complexity
1268  * without parsing them. Example: partial decode of kernel.org certificate:
1269  *  SEQ 0x05ac/1452 bytes (Certificate): 308205ac
1270  *    SEQ 0x0494/1172 bytes (tbsCertificate): 30820494
1271  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0] 3 bytes: a003
1272  *        INTEGER (version): 0201 02
1273  *      INTEGER 0x11 bytes (serialNumber): 0211 00 9f85bf664b0cddafca508679501b2be4
1274  *      //^^^^^^note: matrixSSL also allows [ASN_CONTEXT_SPECIFIC | ASN_PRIMITIVE | 2] = 0x82 type
1275  *      SEQ 0x0d bytes (signatureAlgo): 300d
1276  *        OID 9 bytes: 0609 2a864886f70d01010b (OID_SHA256_RSA_SIG 42.134.72.134.247.13.1.1.11)
1277  *        NULL: 0500
1278  *      SEQ 0x5f bytes (issuer): 305f
1279  *        SET 11 bytes: 310b
1280  *          SEQ 9 bytes: 3009
1281  *            OID 3 bytes: 0603 550406
1282  *            Printable string "FR": 1302 4652
1283  *        SET 14 bytes: 310e
1284  *          SEQ 12 bytes: 300c
1285  *            OID 3 bytes: 0603 550408
1286  *            Printable string "Paris": 1305 5061726973
1287  *        SET 14 bytes: 310e
1288  *          SEQ 12 bytes: 300c
1289  *            OID 3 bytes: 0603 550407
1290  *            Printable string "Paris": 1305 5061726973
1291  *        SET 14 bytes: 310e
1292  *          SEQ 12 bytes: 300c
1293  *            OID 3 bytes: 0603 55040a
1294  *            Printable string "Gandi": 1305 47616e6469
1295  *        SET 32 bytes: 3120
1296  *          SEQ 30 bytes: 301e
1297  *            OID 3 bytes: 0603 550403
1298  *            Printable string "Gandi Standard SSL CA 2": 1317 47616e6469205374616e646172642053534c2043412032
1299  *      SEQ 30 bytes (validity): 301e
1300  *        TIME "161011000000Z": 170d 3136313031313030303030305a
1301  *        TIME "191011235959Z": 170d 3139313031313233353935395a
1302  *      SEQ 0x5b/91 bytes (subject): 305b //I did not decode this
1303  *          3121301f060355040b1318446f6d61696e20436f
1304  *          6e74726f6c2056616c6964617465643121301f06
1305  *          0355040b1318506f73697469766553534c204d75
1306  *          6c74692d446f6d61696e31133011060355040313
1307  *          0a6b65726e656c2e6f7267
1308  *      SEQ 0x01a2/418 bytes (subjectPublicKeyInfo): 308201a2
1309  *        SEQ 13 bytes (algorithm): 300d
1310  *          OID 9 bytes: 0609 2a864886f70d010101 (OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1)
1311  *          NULL: 0500
1312  *        BITSTRING 0x018f/399 bytes (publicKey): 0382018f
1313  *          ????: 00
1314  *          //after the zero byte, it appears key itself uses DER encoding:
1315  *          SEQ 0x018a/394 bytes: 3082018a
1316  *            INTEGER 0x0181/385 bytes (modulus): 02820181
1317  *                  00b1ab2fc727a3bef76780c9349bf3
1318  *                  ...24 more blocks of 15 bytes each...
1319  *                  90e895291c6bc8693b65
1320  *            INTEGER 3 bytes (exponent): 0203 010001
1321  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0x3] 0x01e5 bytes (X509v3 extensions): a38201e5
1322  *        SEQ 0x01e1 bytes: 308201e1
1323  *        ...
1324  * Certificate is a sequence of three elements:
1325  *      tbsCertificate (SEQ)
1326  *      signatureAlgorithm (AlgorithmIdentifier)
1327  *      signatureValue (BIT STRING)
1328  *
1329  * In turn, tbsCertificate is a sequence of:
1330  *      version
1331  *      serialNumber
1332  *      signatureAlgo (AlgorithmIdentifier)
1333  *      issuer (Name, has complex structure)
1334  *      validity (Validity, SEQ of two Times)
1335  *      subject (Name)
1336  *      subjectPublicKeyInfo (SEQ)
1337  *      ...
1338  *
1339  * subjectPublicKeyInfo is a sequence of:
1340  *      algorithm (AlgorithmIdentifier)
1341  *      publicKey (BIT STRING)
1342  *
1343  * We need Certificate.tbsCertificate.subjectPublicKeyInfo.publicKey
1344  *
1345  * Example of an ECDSA key:
1346  *      SEQ 0x59 bytes (subjectPublicKeyInfo): 3059
1347  *        SEQ 0x13 bytes (algorithm): 3013
1348  *          OID 7 bytes: 0607 2a8648ce3d0201   (OID_ECDSA_KEY_ALG 42.134.72.206.61.2.1)
1349  *          OID 8 bytes: 0608 2a8648ce3d030107 (OID_EC_prime256v1 42.134.72.206.61.3.1.7)
1350  *        BITSTRING 0x42 bytes (publicKey): 0342
1351  *          0004 53af f65e 50cc 7959 7e29 0171 c75c
1352  *          7335 e07d f45b 9750 b797 3a38 aebb 2ac6
1353  *          8329 2748 e77e 41cb d482 2ce6 05ec a058
1354  *          f3ab d561 2f4c d845 9ad3 7252 e3de bd3b
1355  *          9012
1356  */
1357         uint8_t *end = der + len;
1358
1359         /* enter "Certificate" item: [der, end) will be only Cert */
1360         der = enter_der_item(der, &end);
1361
1362         /* enter "tbsCertificate" item: [der, end) will be only tbsCert */
1363         der = enter_der_item(der, &end);
1364
1365         /*
1366          * Skip version field only if it is present. For a v1 certificate, the
1367          * version field won't be present since v1 is the default value for the
1368          * version field and fields with default values should be omitted (see
1369          * RFC 5280 sections 4.1 and 4.1.2.1). If the version field is present
1370          * it will have a tag class of 2 (context-specific), bit 6 as 1
1371          * (constructed), and a tag number of 0 (see ITU-T X.690 sections 8.1.2
1372          * and 8.14).
1373          */
1374         /* bits 7-6: 10 */
1375         /* bit 5: 1 */
1376         /* bits 4-0: 00000 */
1377         if (der[0] == 0xa0)
1378                 der = skip_der_item(der, end); /* version */
1379
1380         /* skip up to subjectPublicKeyInfo */
1381         der = skip_der_item(der, end); /* serialNumber */
1382         der = skip_der_item(der, end); /* signatureAlgo */
1383         der = skip_der_item(der, end); /* issuer */
1384         der = skip_der_item(der, end); /* validity */
1385         der = skip_der_item(der, end); /* subject */
1386
1387         /* enter subjectPublicKeyInfo */
1388         der = enter_der_item(der, &end);
1389         { /* check subjectPublicKeyInfo.algorithm */
1390                 static const uint8_t OID_RSA_KEY_ALG[] ALIGN1 = {
1391                         0x30,0x0d, // SEQ 13 bytes
1392                         0x06,0x09, 0x2a,0x86,0x48,0x86,0xf7,0x0d,0x01,0x01,0x01, //OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1
1393                         //0x05,0x00, // NULL
1394                 };
1395                 static const uint8_t OID_ECDSA_KEY_ALG[] ALIGN1 = {
1396                         0x30,0x13, // SEQ 0x13 bytes
1397                         0x06,0x07, 0x2a,0x86,0x48,0xce,0x3d,0x02,0x01,      //OID_ECDSA_KEY_ALG 42.134.72.206.61.2.1
1398                 //allow any curve code for now...
1399                 //      0x06,0x08, 0x2a,0x86,0x48,0xce,0x3d,0x03,0x01,0x07, //OID_EC_prime256v1 42.134.72.206.61.3.1.7
1400                         //RFC 3279:
1401                         //42.134.72.206.61.3     is ellipticCurve
1402                         //42.134.72.206.61.3.0   is c-TwoCurve
1403                         //42.134.72.206.61.3.1   is primeCurve
1404                         //42.134.72.206.61.3.1.7 is curve_secp256r1
1405                 };
1406                 if (memcmp(der, OID_RSA_KEY_ALG, sizeof(OID_RSA_KEY_ALG)) == 0) {
1407                         dbg("RSA key\n");
1408                         tls->flags |= GOT_CERT_RSA_KEY_ALG;
1409                 } else
1410                 if (memcmp(der, OID_ECDSA_KEY_ALG, sizeof(OID_ECDSA_KEY_ALG)) == 0) {
1411                         dbg("ECDSA key\n");
1412                         //UNUSED: tls->flags |= GOT_CERT_ECDSA_KEY_ALG;
1413                 } else
1414                         bb_simple_error_msg_and_die("not RSA or ECDSA cert");
1415         }
1416
1417         if (tls->flags & GOT_CERT_RSA_KEY_ALG) {
1418                 /* parse RSA key: */
1419         //based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note
1420                 /* skip subjectPublicKeyInfo.algorithm */
1421                 der = skip_der_item(der, end);
1422                 /* enter subjectPublicKeyInfo.publicKey */
1423                 //die_if_not_this_der_type(der, end, 0x03); /* must be BITSTRING */
1424                 der = enter_der_item(der, &end);
1425
1426                 dbg("key bytes:%u, first:0x%02x\n", (int)(end - der), der[0]);
1427                 if (end - der < 14)
1428                         xfunc_die();
1429                 /* example format:
1430                  * ignore bits: 00
1431                  * SEQ 0x018a/394 bytes: 3082018a
1432                  *   INTEGER 0x0181/385 bytes (modulus): 02820181 XX...XXX
1433                  *   INTEGER 3 bytes (exponent): 0203 010001
1434                  */
1435                 if (*der != 0) /* "ignore bits", should be 0 */
1436                         xfunc_die();
1437                 der++;
1438                 der = enter_der_item(der, &end); /* enter SEQ */
1439                 /* memset(tls->hsd->server_rsa_pub_key, 0, sizeof(tls->hsd->server_rsa_pub_key)); - already is */
1440                 der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.N, der, end); /* modulus */
1441                 der = skip_der_item(der, end);
1442                 der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.e, der, end); /* exponent */
1443                 tls->hsd->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->hsd->server_rsa_pub_key.N);
1444                 dbg("server_rsa_pub_key.size:%d\n", tls->hsd->server_rsa_pub_key.size);
1445         }
1446         /* else: ECDSA key. It is not used for generating encryption keys,
1447          * it is used only to sign the EC public key (which comes in ServerKey message).
1448          * Since we do not verify cert validity, verifying signature on EC public key
1449          * wouldn't add any security. Thus, we do nothing here.
1450          */
1451 }
1452
1453 /*
1454  * TLS Handshake routines
1455  */
1456 static int tls_xread_handshake_block(tls_state_t *tls, int min_len)
1457 {
1458         struct record_hdr *xhdr;
1459         int len = tls_xread_record(tls, "handshake record");
1460
1461         xhdr = (void*)tls->inbuf;
1462         if (len < min_len
1463          || xhdr->type != RECORD_TYPE_HANDSHAKE
1464         ) {
1465                 bad_record_die(tls, "handshake record", len);
1466         }
1467         dbg("got HANDSHAKE\n");
1468         return len;
1469 }
1470
1471 static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, unsigned len)
1472 {
1473         struct handshake_hdr {
1474                 uint8_t type;
1475                 uint8_t len24_hi, len24_mid, len24_lo;
1476         } *h = buf;
1477
1478         len -= 4;
1479         h->type = type;
1480         h->len24_hi  = len >> 16;
1481         h->len24_mid = len >> 8;
1482         h->len24_lo  = len & 0xff;
1483 }
1484
1485 static void send_client_hello_and_alloc_hsd(tls_state_t *tls, const char *sni)
1486 {
1487 #define NUM_CIPHERS (7 + 6 * ENABLE_FEATURE_TLS_SHA1 + ALLOW_RSA_NULL_SHA256)
1488         static const uint8_t ciphers[] = {
1489                 0x00,2 + NUM_CIPHERS*2, //len16_be
1490                 0x00,0xFF, //not a cipher - TLS_EMPTY_RENEGOTIATION_INFO_SCSV
1491                 /* ^^^^^^ RFC 5746 Renegotiation Indication Extension - some servers will refuse to work with us otherwise */
1492 #if ENABLE_FEATURE_TLS_SHA1
1493                 0xC0,0x09, // 1 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA - ok: wget https://is.gd/
1494                 0xC0,0x0A, // 2 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA - ok: wget https://is.gd/
1495                 0xC0,0x13, // 3 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA
1496                 0xC0,0x14, // 4 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES256-SHA (might fail with older openssl)
1497         //      0xC0,0x18, //   TLS_ECDH_anon_WITH_AES_128_CBC_SHA
1498         //      0xC0,0x19, //   TLS_ECDH_anon_WITH_AES_256_CBC_SHA
1499 #endif
1500                 0xC0,0x23, // 5 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 - ok: wget https://is.gd/
1501         //      0xC0,0x24, //   TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
1502                 0xC0,0x27, // 6 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA256
1503         //      0xC0,0x28, //   TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
1504                 0xC0,0x2B, // 7 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 - ok: wget https://is.gd/
1505         //      0xC0,0x2C, //   TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 - wget https://is.gd/: "TLS error from peer (alert code 20): bad MAC"
1506 //TODO: GCM_SHA384 ciphers can be supported, only need sha384-based PRF?
1507                 0xC0,0x2F, // 8 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-GCM-SHA256
1508         //      0xC0,0x30, //   TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher ECDHE-RSA-AES256-GCM-SHA384: "decryption failed or bad record mac"
1509         //possibly these too:
1510 #if ENABLE_FEATURE_TLS_SHA1
1511         //      0xC0,0x35, //   TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA
1512         //      0xC0,0x36, //   TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA
1513 #endif
1514         //      0xC0,0x37, //   TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256
1515         //      0xC0,0x38, //   TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
1516 #if ENABLE_FEATURE_TLS_SHA1
1517                 0x00,0x2F, // 9 TLS_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher AES128-SHA
1518                 0x00,0x35, //10 TLS_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher AES256-SHA
1519 #endif
1520                 0x00,0x3C, //11 TLS_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher AES128-SHA256
1521                 0x00,0x3D, //12 TLS_RSA_WITH_AES_256_CBC_SHA256 - ok: openssl s_server ... -cipher AES256-SHA256
1522                 0x00,0x9C, //13 TLS_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher AES128-GCM-SHA256
1523         //      0x00,0x9D, //   TLS_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher AES256-GCM-SHA384: "decryption failed or bad record mac"
1524 #if ALLOW_RSA_NULL_SHA256
1525                 0x00,0x3B, //   TLS_RSA_WITH_NULL_SHA256
1526 #endif
1527                 0x01,0x00, //not a cipher - comprtypes_len, comprtype
1528         };
1529         static const uint8_t supported_groups[] = {
1530                 0x00,0x0a, //extension_type: "supported_groups"
1531                 0x00,0x04, //ext len
1532                 0x00,0x02, //list len
1533                 0x00,0x1d, //curve_x25519 (RFC 7748)
1534                 //0x00,0x1e, //curve_x448 (RFC 7748)
1535                 //0x00,0x17, //curve_secp256r1
1536                 //0x00,0x18, //curve_secp384r1
1537                 //0x00,0x19, //curve_secp521r1
1538 //TODO: implement secp256r1 (at least): dl.fedoraproject.org immediately aborts
1539 //if only x25519/x448 are advertised, seems to support only secpNNNr1 curves:
1540 // openssl s_client -connect dl.fedoraproject.org:443 -debug -tls1_2 -cipher ECDHE-RSA-AES128-GCM-SHA256
1541 //Peer signing digest: SHA512
1542 //Peer signature type: RSA
1543 //Server Temp Key: ECDH, P-256, 256 bits
1544 //TLSv1.2, Cipher is ECDHE-RSA-AES128-GCM-SHA256
1545         };
1546         //static const uint8_t signature_algorithms[] = {
1547         //      000d
1548         //      0020
1549         //      001e
1550         //      0601 0602 0603 0501 0502 0503 0401 0402 0403 0301 0302 0303 0201 0202 0203
1551         //};
1552
1553         struct client_hello {
1554                 uint8_t type;
1555                 uint8_t len24_hi, len24_mid, len24_lo;
1556                 uint8_t proto_maj, proto_min;
1557                 uint8_t rand32[32];
1558                 uint8_t session_id_len;
1559                 /* uint8_t session_id[]; */
1560                 uint8_t cipherid_len16_hi, cipherid_len16_lo;
1561                 uint8_t cipherid[2 + NUM_CIPHERS*2]; /* actually variable */
1562                 uint8_t comprtypes_len;
1563                 uint8_t comprtypes[1]; /* actually variable */
1564                 /* Extensions (SNI shown):
1565                  * hi,lo // len of all extensions
1566                  *   00,00 // extension_type: "Server Name"
1567                  *   00,0e // list len (there can be more than one SNI)
1568                  *     00,0c // len of 1st Server Name Indication
1569                  *       00    // name type: host_name
1570                  *       00,09   // name len
1571                  *       "localhost" // name
1572                  */
1573 // GNU Wget 1.18 to cdn.kernel.org sends these extensions:
1574 // 0055
1575 //   0005 0005 0100000000 - status_request
1576 //   0000 0013 0011 00 000e 63646e 2e 6b65726e656c 2e 6f7267 - server_name
1577 //   ff01 0001 00 - renegotiation_info
1578 //   0023 0000 - session_ticket
1579 //   000a 0008 0006001700180019 - supported_groups
1580 //   000b 0002 0100 - ec_point_formats
1581 //   000d 0016 0014 0401 0403 0501 0503 0601 0603 0301 0303 0201 0203 - signature_algorithms
1582 // wolfssl library sends this option, RFC 7627 (closes a security weakness, some servers may require it. TODO?):
1583 //   0017 0000 - extended master secret
1584         };
1585         struct client_hello *record;
1586         uint8_t *ptr;
1587         int len;
1588         int ext_len;
1589         int sni_len = sni ? strnlen(sni, 127 - 5) : 0;
1590
1591         ext_len = 0;
1592         /* is.gd responds with "handshake failure" to our hello if there's no supported_groups element */
1593         ext_len += sizeof(supported_groups);
1594         if (sni_len)
1595                 ext_len += 9 + sni_len;
1596
1597         /* +2 is for "len of all extensions" 2-byte field */
1598         len = sizeof(*record) + 2 + ext_len;
1599         record = tls_get_zeroed_outbuf(tls, len);
1600
1601         fill_handshake_record_hdr(record, HANDSHAKE_CLIENT_HELLO, len);
1602         record->proto_maj = TLS_MAJ;    /* the "requested" version of the protocol, */
1603         record->proto_min = TLS_MIN;    /* can be higher than one in record headers */
1604         tls_get_random(record->rand32, sizeof(record->rand32));
1605         if (TLS_DEBUG_FIXED_SECRETS)
1606                 memset(record->rand32, 0x11, sizeof(record->rand32));
1607         /* record->session_id_len = 0; - already is */
1608
1609         BUILD_BUG_ON(sizeof(ciphers) != 2 + 2 + NUM_CIPHERS*2 + 2);
1610         memcpy(&record->cipherid_len16_hi, ciphers, sizeof(ciphers));
1611
1612         ptr = (void*)(record + 1);
1613         *ptr++ = ext_len >> 8;
1614         *ptr++ = ext_len;
1615         if (sni_len) {
1616                 //ptr[0] = 0;             //
1617                 //ptr[1] = 0;             //extension_type
1618                 //ptr[2] = 0;         //
1619                 ptr[3] = sni_len + 5; //list len
1620                 //ptr[4] = 0;             //
1621                 ptr[5] = sni_len + 3;     //len of 1st SNI
1622                 //ptr[6] = 0;         //name type
1623                 //ptr[7] = 0;             //
1624                 ptr[8] = sni_len;         //name len
1625                 ptr = mempcpy(&ptr[9], sni, sni_len);
1626         }
1627         memcpy(ptr, supported_groups, sizeof(supported_groups));
1628
1629         tls->hsd = xzalloc(sizeof(*tls->hsd));
1630         /* HANDSHAKE HASH: ^^^ + len if need to save saved_client_hello */
1631         memcpy(tls->hsd->client_and_server_rand32, record->rand32, sizeof(record->rand32));
1632 /* HANDSHAKE HASH:
1633         tls->hsd->saved_client_hello_size = len;
1634         memcpy(tls->hsd->saved_client_hello, record, len);
1635  */
1636         dbg(">> CLIENT_HELLO\n");
1637         /* Can hash immediately only if we know which MAC hash to use.
1638          * So far we do know: it's sha256:
1639          */
1640         sha256_begin(&tls->hsd->handshake_hash_ctx);
1641         xwrite_and_update_handshake_hash(tls, len);
1642         /* if this would become infeasible: save tls->hsd->saved_client_hello,
1643          * use "xwrite_handshake_record(tls, len)" here,
1644          * and hash saved_client_hello later.
1645          */
1646 }
1647
1648 static void get_server_hello(tls_state_t *tls)
1649 {
1650         struct server_hello {
1651                 struct record_hdr xhdr;
1652                 uint8_t type;
1653                 uint8_t len24_hi, len24_mid, len24_lo;
1654                 uint8_t proto_maj, proto_min;
1655                 uint8_t rand32[32]; /* first 4 bytes are unix time in BE format */
1656                 uint8_t session_id_len;
1657                 uint8_t session_id[32];
1658                 uint8_t cipherid_hi, cipherid_lo;
1659                 uint8_t comprtype;
1660                 /* extensions may follow, but only those which client offered in its Hello */
1661         };
1662
1663         struct server_hello *hp;
1664         uint8_t *cipherid;
1665         uint8_t cipherid1;
1666         int len, len24;
1667
1668         len = tls_xread_handshake_block(tls, 74 - 32);
1669
1670         hp = (void*)tls->inbuf;
1671         // 74 bytes:
1672         // 02  000046 03|03   58|78|cf|c1 50|a5|49|ee|7e|29|48|71|fe|97|fa|e8|2d|19|87|72|90|84|9d|37|a3|f0|cb|6f|5f|e3|3c|2f |20  |d8|1a|78|96|52|d6|91|01|24|b3|d6|5b|b7|d0|6c|b3|e1|78|4e|3c|95|de|74|a0|ba|eb|a7|3a|ff|bd|a2|bf |00|9c |00|
1673         //SvHl len=70 maj.min unixtime^^^ 28randbytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^ slen sid32bytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cipSel comprSel
1674         if (hp->type != HANDSHAKE_SERVER_HELLO
1675          || hp->len24_hi  != 0
1676          || hp->len24_mid != 0
1677          /* hp->len24_lo checked later */
1678          || hp->proto_maj != TLS_MAJ
1679          || hp->proto_min != TLS_MIN
1680         ) {
1681                 bad_record_die(tls, "'server hello'", len);
1682         }
1683
1684         cipherid = &hp->cipherid_hi;
1685         len24 = hp->len24_lo;
1686         if (hp->session_id_len != 32) {
1687                 if (hp->session_id_len != 0)
1688                         bad_record_die(tls, "'server hello'", len);
1689
1690                 // session_id_len == 0: no session id
1691                 // "The server
1692                 // may return an empty session_id to indicate that the session will
1693                 // not be cached and therefore cannot be resumed."
1694                 cipherid -= 32;
1695                 len24 += 32; /* what len would be if session id would be present */
1696         }
1697
1698         if (len24 < 70)
1699                 bad_record_die(tls, "'server hello'", len);
1700         dbg("<< SERVER_HELLO\n");
1701
1702         memcpy(tls->hsd->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32));
1703
1704         /* Set up encryption params based on selected cipher */
1705 #if 0
1706 #if ENABLE_FEATURE_TLS_SHA1
1707                 0xC0,0x09, // 1 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA - ok: wget https://is.gd/
1708                 0xC0,0x0A, // 2 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA - ok: wget https://is.gd/
1709                 0xC0,0x13, // 3 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA
1710                 0xC0,0x14, // 4 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES256-SHA (might fail with older openssl)
1711         //      0xC0,0x18, //   TLS_ECDH_anon_WITH_AES_128_CBC_SHA
1712         //      0xC0,0x19, //   TLS_ECDH_anon_WITH_AES_256_CBC_SHA
1713 #endif
1714                 0xC0,0x23, // 5 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 - ok: wget https://is.gd/
1715         //      0xC0,0x24, //   TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
1716                 0xC0,0x27, // 6 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA256
1717         //      0xC0,0x28, //   TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
1718                 0xC0,0x2B, // 7 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 - ok: wget https://is.gd/
1719         //      0xC0,0x2C, //   TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 - wget https://is.gd/: "TLS error from peer (alert code 20): bad MAC"
1720 //TODO: GCM_SHA384 ciphers can be supported, only need sha384-based PRF?
1721                 0xC0,0x2F, // 8 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-GCM-SHA256
1722         //      0xC0,0x30, //   TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher ECDHE-RSA-AES256-GCM-SHA384: "decryption failed or bad record mac"
1723         //possibly these too:
1724 #if ENABLE_FEATURE_TLS_SHA1
1725         //      0xC0,0x35, //   TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA
1726         //      0xC0,0x36, //   TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA
1727 #endif
1728         //      0xC0,0x37, //   TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256
1729         //      0xC0,0x38, //   TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
1730 #if ENABLE_FEATURE_TLS_SHA1
1731                 0x00,0x2F, // 9 TLS_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher AES128-SHA
1732                 0x00,0x35, //10 TLS_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher AES256-SHA
1733 #endif
1734                 0x00,0x3C, //11 TLS_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher AES128-SHA256
1735                 0x00,0x3D, //12 TLS_RSA_WITH_AES_256_CBC_SHA256 - ok: openssl s_server ... -cipher AES256-SHA256
1736                 0x00,0x9C, //13 TLS_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher AES128-GCM-SHA256
1737         //      0x00,0x9D, //   TLS_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher AES256-GCM-SHA384: "decryption failed or bad record mac"
1738 #if ALLOW_RSA_NULL_SHA256
1739                 0x00,0x3B, //   TLS_RSA_WITH_NULL_SHA256
1740 #endif
1741 #endif
1742         cipherid1 = cipherid[1];
1743         tls->cipher_id = 0x100 * cipherid[0] + cipherid1;
1744         tls->key_size = AES256_KEYSIZE;
1745         tls->MAC_size = SHA256_OUTSIZE;
1746         /*tls->IV_size = 0; - already is */
1747         if (cipherid[0] == 0xC0) {
1748                 /* All C0xx are ECDHE */
1749                 tls->flags |= NEED_EC_KEY;
1750                 if (cipherid1 & 1) {
1751                         /* Odd numbered C0xx use AES128 (even ones use AES256) */
1752                         tls->key_size = AES128_KEYSIZE;
1753                 }
1754                 if (ENABLE_FEATURE_TLS_SHA1 && cipherid1 <= 0x19) {
1755                         tls->MAC_size = SHA1_OUTSIZE;
1756                 } else
1757                 if (cipherid1 >= 0x2B && cipherid1 <= 0x30) {
1758                         /* C02B,2C,2F,30 are AES-GCM */
1759                         tls->flags |= ENCRYPTION_AESGCM;
1760                         tls->MAC_size = 0;
1761                         tls->IV_size = 4;
1762                 }
1763         } else {
1764                 /* All 00xx are RSA */
1765                 if ((ENABLE_FEATURE_TLS_SHA1 && cipherid1 == 0x2F)
1766                  || cipherid1 == 0x3C
1767                  || cipherid1 == 0x9C
1768                 ) {
1769                         tls->key_size = AES128_KEYSIZE;
1770                 }
1771                 if (ENABLE_FEATURE_TLS_SHA1 && cipherid1 <= 0x35) {
1772                         tls->MAC_size = SHA1_OUTSIZE;
1773                 } else
1774                 if (cipherid1 == 0x9C /*|| cipherid1 == 0x9D*/) {
1775                         /* 009C,9D are AES-GCM */
1776                         tls->flags |= ENCRYPTION_AESGCM;
1777                         tls->MAC_size = 0;
1778                         tls->IV_size = 4;
1779                 }
1780         }
1781         dbg("server chose cipher %04x\n", tls->cipher_id);
1782         dbg("key_size:%u MAC_size:%u IV_size:%u\n", tls->key_size, tls->MAC_size, tls->IV_size);
1783
1784         /* Handshake hash eventually destined to FINISHED record
1785          * is sha256 regardless of cipher
1786          * (at least for all ciphers defined by RFC5246).
1787          * It's not sha1 for AES_128_CBC_SHA - only MAC is sha1, not this hash.
1788          */
1789 /* HANDSHAKE HASH:
1790         sha256_begin(&tls->hsd->handshake_hash_ctx);
1791         hash_handshake(tls, ">> client hello hash:%s",
1792                 tls->hsd->saved_client_hello, tls->hsd->saved_client_hello_size
1793         );
1794         hash_handshake(tls, "<< server hello hash:%s",
1795                 tls->inbuf + RECHDR_LEN, len
1796         );
1797  */
1798 }
1799
1800 static void get_server_cert(tls_state_t *tls)
1801 {
1802         struct record_hdr *xhdr;
1803         uint8_t *certbuf;
1804         int len, len1;
1805
1806         len = tls_xread_handshake_block(tls, 10);
1807
1808         xhdr = (void*)tls->inbuf;
1809         certbuf = (void*)(xhdr + 1);
1810         if (certbuf[0] != HANDSHAKE_CERTIFICATE)
1811                 bad_record_die(tls, "certificate", len);
1812         dbg("<< CERTIFICATE\n");
1813         // 4392 bytes:
1814         // 0b  00|11|24 00|11|21 00|05|b0 30|82|05|ac|30|82|04|94|a0|03|02|01|02|02|11|00|9f|85|bf|66|4b|0c|dd|af|ca|50|86|79|50|1b|2b|e4|30|0d...
1815         //Cert len=4388 ChainLen CertLen^ DER encoded X509 starts here. openssl x509 -in FILE -inform DER -noout -text
1816         len1 = get24be(certbuf + 1);
1817         if (len1 > len - 4) tls_error_die(tls);
1818         len = len1;
1819         len1 = get24be(certbuf + 4);
1820         if (len1 > len - 3) tls_error_die(tls);
1821         len = len1;
1822         len1 = get24be(certbuf + 7);
1823         if (len1 > len - 3) tls_error_die(tls);
1824         len = len1;
1825
1826         if (len)
1827                 find_key_in_der_cert(tls, certbuf + 10, len);
1828 }
1829
1830 /* On input, len is known to be >= 4.
1831  * The record is known to be SERVER_KEY_EXCHANGE.
1832  */
1833 static void process_server_key(tls_state_t *tls, int len)
1834 {
1835         struct record_hdr *xhdr;
1836         uint8_t *keybuf;
1837         int len1;
1838         uint32_t t32;
1839
1840         xhdr = (void*)tls->inbuf;
1841         keybuf = (void*)(xhdr + 1);
1842 //seen from is.gd: it selects curve_x25519:
1843 //  0c 00006e //SERVER_KEY_EXCHANGE, len
1844 //    03 //curve_type: named curve
1845 //    001d //curve_x25519
1846 //server-chosen EC point, and then signed_params
1847 //      (RFC 8422: "A hash of the params, with the signature
1848 //      appropriate to that hash applied.  The private key corresponding
1849 //      to the certified public key in the server's Certificate message is
1850 //      used for signing.")
1851 //follow. Format unclear/guessed:
1852 //    20 //eccPubKeyLen
1853 //      25511923d73b70dd2f60e66ba2f3fda31a9c25170963c7a3a972e481dbb2835d //eccPubKey (32bytes)
1854 //    0203 //hashSigAlg: 2:SHA1 (4:SHA256 5:SHA384 6:SHA512), 3:ECDSA (1:RSA)
1855 //    0046 //len (16bit)
1856 //      30 44 //SEQ, len
1857 //        02 20 //INTEGER, len
1858 //          2e18e7c2a9badd0a70cd3059a6ab114539b9f5163568911147386cd77ed7c412 //32bytes
1859 //this item ^^^^^ is sometimes 33 bytes (with all container sizes also +1)
1860 //        02 20 //INTEGER, len
1861 //          64523d6216cb94c43c9b20e377d8c52c55be6703fd6730a155930c705eaf3af6 //32bytes
1862 //same about this item ^^^^^
1863
1864 //seen from ftp.openbsd.org
1865 //(which only accepts ECDHE-RSA-AESnnn-GCM-SHAnnn and ECDHE-RSA-CHACHA20-POLY1305 ciphers):
1866 //  0c 000228 //SERVER_KEY_EXCHANGE, len
1867 //    03 //curve_type: named curve
1868 //    001d //curve_x25519
1869 //    20 //eccPubKeyLen
1870 //      eef7a15c43b71a4c7eaa48a39369399cc4332e569ec90a83274cc92596705c1a //eccPubKey
1871 //    0401 //hashSigAlg: 4:SHA256, 1:RSA
1872 //    0200 //len
1873 //      //0x200 bytes follow
1874
1875         /* Get and verify length */
1876         len1 = get24be(keybuf + 1);
1877         if (len1 > len - 4) tls_error_die(tls);
1878         len = len1;
1879         if (len < (1+2+1+32)) tls_error_die(tls);
1880         keybuf += 4;
1881
1882         /* So far we only support curve_x25519 */
1883         move_from_unaligned32(t32, keybuf);
1884         if (t32 != htonl(0x03001d20))
1885                 bb_simple_error_msg_and_die("elliptic curve is not x25519");
1886
1887         memcpy(tls->hsd->ecc_pub_key32, keybuf + 4, 32);
1888         tls->flags |= GOT_EC_KEY;
1889         dbg("got eccPubKey\n");
1890 }
1891
1892 static void send_empty_client_cert(tls_state_t *tls)
1893 {
1894         struct client_empty_cert {
1895                 uint8_t type;
1896                 uint8_t len24_hi, len24_mid, len24_lo;
1897                 uint8_t cert_chain_len24_hi, cert_chain_len24_mid, cert_chain_len24_lo;
1898         };
1899         struct client_empty_cert *record;
1900
1901         record = tls_get_zeroed_outbuf(tls, sizeof(*record));
1902         //fill_handshake_record_hdr(record, HANDSHAKE_CERTIFICATE, sizeof(*record));
1903         //record->cert_chain_len24_hi = 0;
1904         //record->cert_chain_len24_mid = 0;
1905         //record->cert_chain_len24_lo = 0;
1906         // same as above:
1907         record->type = HANDSHAKE_CERTIFICATE;
1908         record->len24_lo = 3;
1909
1910         dbg(">> CERTIFICATE\n");
1911         xwrite_and_update_handshake_hash(tls, sizeof(*record));
1912 }
1913
1914 static void send_client_key_exchange(tls_state_t *tls)
1915 {
1916         struct client_key_exchange {
1917                 uint8_t type;
1918                 uint8_t len24_hi, len24_mid, len24_lo;
1919                 uint8_t key[2 + 4 * 1024]; // size??
1920         };
1921 //FIXME: better size estimate
1922         struct client_key_exchange *record = tls_get_zeroed_outbuf(tls, sizeof(*record));
1923         uint8_t rsa_premaster[RSA_PREMASTER_SIZE];
1924         uint8_t x25519_premaster[CURVE25519_KEYSIZE];
1925         uint8_t *premaster;
1926         int premaster_size;
1927         int len;
1928
1929         if (!(tls->flags & NEED_EC_KEY)) {
1930                 /* RSA */
1931                 if (!(tls->flags & GOT_CERT_RSA_KEY_ALG))
1932                         bb_simple_error_msg("server cert is not RSA");
1933
1934                 tls_get_random(rsa_premaster, sizeof(rsa_premaster));
1935                 if (TLS_DEBUG_FIXED_SECRETS)
1936                         memset(rsa_premaster, 0x44, sizeof(rsa_premaster));
1937                 // RFC 5246
1938                 // "Note: The version number in the PreMasterSecret is the version
1939                 // offered by the client in the ClientHello.client_version, not the
1940                 // version negotiated for the connection."
1941                 rsa_premaster[0] = TLS_MAJ;
1942                 rsa_premaster[1] = TLS_MIN;
1943                 dump_hex("premaster:%s\n", rsa_premaster, sizeof(rsa_premaster));
1944                 len = psRsaEncryptPub(/*pool:*/ NULL,
1945                         /* psRsaKey_t* */ &tls->hsd->server_rsa_pub_key,
1946                         rsa_premaster, /*inlen:*/ sizeof(rsa_premaster),
1947                         record->key + 2, sizeof(record->key) - 2,
1948                         data_param_ignored
1949                 );
1950                 /* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */
1951                 record->key[0] = len >> 8;
1952                 record->key[1] = len & 0xff;
1953                 len += 2;
1954                 premaster = rsa_premaster;
1955                 premaster_size = sizeof(rsa_premaster);
1956         } else {
1957                 /* ECDHE */
1958                 static const uint8_t basepoint9[CURVE25519_KEYSIZE] = {9};
1959                 uint8_t privkey[CURVE25519_KEYSIZE]; //[32]
1960
1961                 if (!(tls->flags & GOT_EC_KEY))
1962                         bb_simple_error_msg("server did not provide EC key");
1963
1964                 /* Generate random private key, see RFC 7748 */
1965                 tls_get_random(privkey, sizeof(privkey));
1966                 privkey[0] &= 0xf8;
1967                 privkey[CURVE25519_KEYSIZE-1] = ((privkey[CURVE25519_KEYSIZE-1] & 0x7f) | 0x40);
1968
1969                 /* Compute public key */
1970                 curve25519(record->key + 1, privkey, basepoint9);
1971
1972                 /* Compute premaster using peer's public key */
1973                 dbg("computing x25519_premaster\n");
1974                 curve25519(x25519_premaster, privkey, tls->hsd->ecc_pub_key32);
1975
1976                 len = CURVE25519_KEYSIZE;
1977                 record->key[0] = len;
1978                 len++;
1979                 premaster = x25519_premaster;
1980                 premaster_size = sizeof(x25519_premaster);
1981         }
1982
1983         record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
1984         /* record->len24_hi = 0; - already is */
1985         record->len24_mid = len >> 8;
1986         record->len24_lo  = len & 0xff;
1987         len += 4;
1988
1989         dbg(">> CLIENT_KEY_EXCHANGE\n");
1990         xwrite_and_update_handshake_hash(tls, len);
1991
1992         // RFC 5246
1993         // For all key exchange methods, the same algorithm is used to convert
1994         // the pre_master_secret into the master_secret.  The pre_master_secret
1995         // should be deleted from memory once the master_secret has been
1996         // computed.
1997         //      master_secret = PRF(pre_master_secret, "master secret",
1998         //                          ClientHello.random + ServerHello.random)
1999         //                          [0..47];
2000         // The master secret is always exactly 48 bytes in length.  The length
2001         // of the premaster secret will vary depending on key exchange method.
2002         prf_hmac_sha256(/*tls,*/
2003                 tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
2004                 premaster, premaster_size,
2005                 "master secret",
2006                 tls->hsd->client_and_server_rand32, sizeof(tls->hsd->client_and_server_rand32)
2007         );
2008         dump_hex("master secret:%s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
2009
2010         // RFC 5246
2011         // 6.3.  Key Calculation
2012         //
2013         // The Record Protocol requires an algorithm to generate keys required
2014         // by the current connection state (see Appendix A.6) from the security
2015         // parameters provided by the handshake protocol.
2016         //
2017         // The master secret is expanded into a sequence of secure bytes, which
2018         // is then split to a client write MAC key, a server write MAC key, a
2019         // client write encryption key, and a server write encryption key.  Each
2020         // of these is generated from the byte sequence in that order.  Unused
2021         // values are empty.  Some AEAD ciphers may additionally require a
2022         // client write IV and a server write IV (see Section 6.2.3.3).
2023         //
2024         // When keys and MAC keys are generated, the master secret is used as an
2025         // entropy source.
2026         //
2027         // To generate the key material, compute
2028         //
2029         //    key_block = PRF(SecurityParameters.master_secret,
2030         //                    "key expansion",
2031         //                    SecurityParameters.server_random +
2032         //                    SecurityParameters.client_random);
2033         //
2034         // until enough output has been generated.  Then, the key_block is
2035         // partitioned as follows:
2036         //
2037         //    client_write_MAC_key[SecurityParameters.mac_key_length]
2038         //    server_write_MAC_key[SecurityParameters.mac_key_length]
2039         //    client_write_key[SecurityParameters.enc_key_length]
2040         //    server_write_key[SecurityParameters.enc_key_length]
2041         //    client_write_IV[SecurityParameters.fixed_iv_length]
2042         //    server_write_IV[SecurityParameters.fixed_iv_length]
2043         {
2044                 uint8_t tmp64[64];
2045
2046                 /* make "server_rand32 + client_rand32" */
2047                 memcpy(&tmp64[0] , &tls->hsd->client_and_server_rand32[32], 32);
2048                 memcpy(&tmp64[32], &tls->hsd->client_and_server_rand32[0] , 32);
2049
2050                 prf_hmac_sha256(/*tls,*/
2051                         tls->client_write_MAC_key, 2 * (tls->MAC_size + tls->key_size + tls->IV_size),
2052                         // also fills:
2053                         // server_write_MAC_key[]
2054                         // client_write_key[]
2055                         // server_write_key[]
2056                         // client_write_IV[]
2057                         // server_write_IV[]
2058                         tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
2059                         "key expansion",
2060                         tmp64, 64
2061                 );
2062                 tls->client_write_key = tls->client_write_MAC_key + (2 * tls->MAC_size);
2063                 tls->server_write_key = tls->client_write_key + tls->key_size;
2064                 tls->client_write_IV = tls->server_write_key + tls->key_size;
2065                 tls->server_write_IV = tls->client_write_IV + tls->IV_size;
2066                 dump_hex("client_write_MAC_key:%s\n",
2067                         tls->client_write_MAC_key, tls->MAC_size
2068                 );
2069                 dump_hex("client_write_key:%s\n",
2070                         tls->client_write_key, tls->key_size
2071                 );
2072                 dump_hex("client_write_IV:%s\n",
2073                         tls->client_write_IV, tls->IV_size
2074                 );
2075
2076                 aes_setkey(&tls->aes_decrypt, tls->server_write_key, tls->key_size);
2077                 aes_setkey(&tls->aes_encrypt, tls->client_write_key, tls->key_size);
2078                 {
2079                         uint8_t iv[AES_BLOCK_SIZE];
2080                         memset(iv, 0, AES_BLOCK_SIZE);
2081                         aes_encrypt_one_block(&tls->aes_encrypt, iv, tls->H);
2082                 }
2083         }
2084 }
2085
2086 static const uint8_t rec_CHANGE_CIPHER_SPEC[] ALIGN1 = {
2087         RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01,
2088         01
2089 };
2090
2091 static void send_change_cipher_spec(tls_state_t *tls)
2092 {
2093         dbg(">> CHANGE_CIPHER_SPEC\n");
2094         xwrite(tls->ofd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC));
2095 }
2096
2097 // 7.4.9.  Finished
2098 // A Finished message is always sent immediately after a change
2099 // cipher spec message to verify that the key exchange and
2100 // authentication processes were successful.  It is essential that a
2101 // change cipher spec message be received between the other handshake
2102 // messages and the Finished message.
2103 //...
2104 // The Finished message is the first one protected with the just
2105 // negotiated algorithms, keys, and secrets.  Recipients of Finished
2106 // messages MUST verify that the contents are correct.  Once a side
2107 // has sent its Finished message and received and validated the
2108 // Finished message from its peer, it may begin to send and receive
2109 // application data over the connection.
2110 //...
2111 // struct {
2112 //     opaque verify_data[verify_data_length];
2113 // } Finished;
2114 //
2115 // verify_data
2116 //    PRF(master_secret, finished_label, Hash(handshake_messages))
2117 //       [0..verify_data_length-1];
2118 //
2119 // finished_label
2120 //    For Finished messages sent by the client, the string
2121 //    "client finished".  For Finished messages sent by the server,
2122 //    the string "server finished".
2123 //
2124 // Hash denotes a Hash of the handshake messages.  For the PRF
2125 // defined in Section 5, the Hash MUST be the Hash used as the basis
2126 // for the PRF.  Any cipher suite which defines a different PRF MUST
2127 // also define the Hash to use in the Finished computation.
2128 //
2129 // In previous versions of TLS, the verify_data was always 12 octets
2130 // long.  In the current version of TLS, it depends on the cipher
2131 // suite.  Any cipher suite which does not explicitly specify
2132 // verify_data_length has a verify_data_length equal to 12.  This
2133 // includes all existing cipher suites.
2134 static void send_client_finished(tls_state_t *tls)
2135 {
2136         struct finished {
2137                 uint8_t type;
2138                 uint8_t len24_hi, len24_mid, len24_lo;
2139                 uint8_t prf_result[12];
2140         };
2141         struct finished *record = tls_get_outbuf(tls, sizeof(*record));
2142         uint8_t handshake_hash[TLS_MAX_MAC_SIZE];
2143         unsigned len;
2144
2145         fill_handshake_record_hdr(record, HANDSHAKE_FINISHED, sizeof(*record));
2146
2147         len = sha_end(&tls->hsd->handshake_hash_ctx, handshake_hash);
2148
2149         prf_hmac_sha256(/*tls,*/
2150                 record->prf_result, sizeof(record->prf_result),
2151                 tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
2152                 "client finished",
2153                 handshake_hash, len
2154         );
2155         dump_hex("from secret: %s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
2156         dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1);
2157         dump_hex("%s\n", handshake_hash, sizeof(handshake_hash));
2158         dump_hex("=> digest: %s\n", record->prf_result, sizeof(record->prf_result));
2159
2160         dbg(">> FINISHED\n");
2161         xwrite_encrypted(tls, sizeof(*record), RECORD_TYPE_HANDSHAKE);
2162 }
2163
2164 void FAST_FUNC tls_handshake(tls_state_t *tls, const char *sni)
2165 {
2166         // Client              RFC 5246                Server
2167         // (*) - optional messages, not always sent
2168         //
2169         // ClientHello          ------->
2170         //                                        ServerHello
2171         //                                       Certificate*
2172         //                                 ServerKeyExchange*
2173         //                                CertificateRequest*
2174         //                      <-------      ServerHelloDone
2175         // Certificate*
2176         // ClientKeyExchange
2177         // CertificateVerify*
2178         // [ChangeCipherSpec]
2179         // Finished             ------->
2180         //                                 [ChangeCipherSpec]
2181         //                      <-------             Finished
2182         // Application Data     <------>     Application Data
2183         int len;
2184         int got_cert_req;
2185
2186         send_client_hello_and_alloc_hsd(tls, sni);
2187         get_server_hello(tls);
2188
2189         // RFC 5246
2190         // The server MUST send a Certificate message whenever the agreed-
2191         // upon key exchange method uses certificates for authentication
2192         // (this includes all key exchange methods defined in this document
2193         // except DH_anon).  This message will always immediately follow the
2194         // ServerHello message.
2195         //
2196         // IOW: in practice, Certificate *always* follows.
2197         // (for example, kernel.org does not even accept DH_anon cipher id)
2198         get_server_cert(tls);
2199
2200         len = tls_xread_handshake_block(tls, 4);
2201         if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_SERVER_KEY_EXCHANGE) {
2202                 // 459 bytes:
2203                 // 0c   00|01|c7 03|00|17|41|04|87|94|2e|2f|68|d0|c9|f4|97|a8|2d|ef|ed|67|ea|c6|f3|b3|56|47|5d|27|b6|bd|ee|70|25|30|5e|b0|8e|f6|21|5a...
2204                 //SvKey len=455^
2205                 // with TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: 461 bytes:
2206                 // 0c   00|01|c9 03|00|17|41|04|cd|9b|b4|29|1f|f6|b0|c2|84|82|7f|29|6a|47|4e|ec|87|0b|c1|9c|69|e1|f8|c6|d0|53|e9|27|90|a5|c8|02|15|75...
2207                 //
2208                 // RFC 8422 5.4. Server Key Exchange
2209                 // This message is sent when using the ECDHE_ECDSA, ECDHE_RSA, and
2210                 // ECDH_anon key exchange algorithms.
2211                 // This message is used to convey the server's ephemeral ECDH public key
2212                 // (and the corresponding elliptic curve domain parameters) to the
2213                 // client.
2214                 dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len);
2215                 dump_raw_in("<< %s\n", tls->inbuf, RECHDR_LEN + len);
2216                 if (tls->flags & NEED_EC_KEY)
2217                         process_server_key(tls, len);
2218
2219                 // read next handshake block
2220                 len = tls_xread_handshake_block(tls, 4);
2221         }
2222
2223         got_cert_req = (tls->inbuf[RECHDR_LEN] == HANDSHAKE_CERTIFICATE_REQUEST);
2224         if (got_cert_req) {
2225                 dbg("<< CERTIFICATE_REQUEST\n");
2226                 // RFC 5246: "If no suitable certificate is available,
2227                 // the client MUST send a certificate message containing no
2228                 // certificates.  That is, the certificate_list structure has a
2229                 // length of zero. ...
2230                 // Client certificates are sent using the Certificate structure
2231                 // defined in Section 7.4.2."
2232                 // (i.e. the same format as server certs)
2233
2234                 /*send_empty_client_cert(tls); - WRONG (breaks handshake hash calc) */
2235                 /* need to hash _all_ server replies first, up to ServerHelloDone */
2236                 len = tls_xread_handshake_block(tls, 4);
2237         }
2238
2239         if (tls->inbuf[RECHDR_LEN] != HANDSHAKE_SERVER_HELLO_DONE) {
2240                 bad_record_die(tls, "'server hello done'", len);
2241         }
2242         // 0e 000000 (len:0)
2243         dbg("<< SERVER_HELLO_DONE\n");
2244
2245         if (got_cert_req)
2246                 send_empty_client_cert(tls);
2247
2248         send_client_key_exchange(tls);
2249
2250         send_change_cipher_spec(tls);
2251         /* from now on we should send encrypted */
2252         /* tls->write_seq64_be = 0; - already is */
2253         tls->flags |= ENCRYPT_ON_WRITE;
2254
2255         send_client_finished(tls);
2256
2257         /* Get CHANGE_CIPHER_SPEC */
2258         len = tls_xread_record(tls, "switch to encrypted traffic");
2259         if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0)
2260                 bad_record_die(tls, "switch to encrypted traffic", len);
2261         dbg("<< CHANGE_CIPHER_SPEC\n");
2262
2263         if (ALLOW_RSA_NULL_SHA256
2264          && tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
2265         ) {
2266                 tls->min_encrypted_len_on_read = tls->MAC_size;
2267         } else
2268         if (!(tls->flags & ENCRYPTION_AESGCM)) {
2269                 unsigned mac_blocks = (unsigned)(TLS_MAC_SIZE(tls) + AES_BLOCK_SIZE-1) / AES_BLOCK_SIZE;
2270                 /* all incoming packets now should be encrypted and have
2271                  * at least IV + (MAC padded to blocksize):
2272                  */
2273                 tls->min_encrypted_len_on_read = AES_BLOCK_SIZE + (mac_blocks * AES_BLOCK_SIZE);
2274         } else {
2275                 tls->min_encrypted_len_on_read = 8 + AES_BLOCK_SIZE;
2276         }
2277         dbg("min_encrypted_len_on_read: %u\n", tls->min_encrypted_len_on_read);
2278
2279         /* Get (encrypted) FINISHED from the server */
2280         len = tls_xread_record(tls, "'server finished'");
2281         if (len < 4 || tls->inbuf[RECHDR_LEN] != HANDSHAKE_FINISHED)
2282                 bad_record_die(tls, "'server finished'", len);
2283         dbg("<< FINISHED\n");
2284         /* application data can be sent/received */
2285
2286         /* free handshake data */
2287         psRsaKey_clear(&tls->hsd->server_rsa_pub_key);
2288 //      if (PARANOIA)
2289 //              memset(tls->hsd, 0, tls->hsd->hsd_size);
2290         free(tls->hsd);
2291         tls->hsd = NULL;
2292 }
2293
2294 static void tls_xwrite(tls_state_t *tls, int len)
2295 {
2296         dbg(">> DATA\n");
2297         xwrite_encrypted(tls, len, RECORD_TYPE_APPLICATION_DATA);
2298 }
2299
2300 // To run a test server using openssl:
2301 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
2302 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2
2303 //
2304 // Unencryped SHA256 example:
2305 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
2306 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -cipher NULL
2307 // openssl s_client -connect 127.0.0.1:4433 -debug -tls1_2 -cipher NULL-SHA256
2308
2309 void FAST_FUNC tls_run_copy_loop(tls_state_t *tls, unsigned flags)
2310 {
2311         int inbuf_size;
2312         const int INBUF_STEP = 4 * 1024;
2313         struct pollfd pfds[2];
2314
2315         pfds[0].fd = STDIN_FILENO;
2316         pfds[0].events = POLLIN;
2317         pfds[1].fd = tls->ifd;
2318         pfds[1].events = POLLIN;
2319
2320         inbuf_size = INBUF_STEP;
2321         for (;;) {
2322                 int nread;
2323
2324                 if (safe_poll(pfds, 2, -1) < 0)
2325                         bb_simple_perror_msg_and_die("poll");
2326
2327                 if (pfds[0].revents) {
2328                         void *buf;
2329
2330                         dbg("STDIN HAS DATA\n");
2331                         buf = tls_get_outbuf(tls, inbuf_size);
2332                         nread = safe_read(STDIN_FILENO, buf, inbuf_size);
2333                         if (nread < 1) {
2334                                 /* We'd want to do this: */
2335                                 /* Close outgoing half-connection so they get EOF,
2336                                  * but leave incoming alone so we can see response
2337                                  */
2338                                 //shutdown(tls->ofd, SHUT_WR);
2339                                 /* But TLS has no way to encode this,
2340                                  * doubt it's ok to do it "raw"
2341                                  */
2342                                 pfds[0].fd = -1;
2343                                 tls_free_outbuf(tls); /* mem usage optimization */
2344                                 if (flags & TLSLOOP_EXIT_ON_LOCAL_EOF)
2345                                         break;
2346                         } else {
2347                                 if (nread == inbuf_size) {
2348                                         /* TLS has per record overhead, if input comes fast,
2349                                          * read, encrypt and send bigger chunks
2350                                          */
2351                                         inbuf_size += INBUF_STEP;
2352                                         if (inbuf_size > TLS_MAX_OUTBUF)
2353                                                 inbuf_size = TLS_MAX_OUTBUF;
2354                                 }
2355                                 tls_xwrite(tls, nread);
2356                         }
2357                 }
2358                 if (pfds[1].revents) {
2359                         dbg("NETWORK HAS DATA\n");
2360  read_record:
2361                         nread = tls_xread_record(tls, "encrypted data");
2362                         if (nread < 1) {
2363                                 /* TLS protocol has no real concept of one-sided shutdowns:
2364                                  * if we get "TLS EOF" from the peer, writes will fail too
2365                                  */
2366                                 //pfds[1].fd = -1;
2367                                 //close(STDOUT_FILENO);
2368                                 //tls_free_inbuf(tls); /* mem usage optimization */
2369                                 //continue;
2370                                 break;
2371                         }
2372                         if (tls->inbuf[0] != RECORD_TYPE_APPLICATION_DATA)
2373                                 bad_record_die(tls, "encrypted data", nread);
2374                         xwrite(STDOUT_FILENO, tls->inbuf + RECHDR_LEN, nread);
2375                         /* We may already have a complete next record buffered,
2376                          * can process it without network reads (and possible blocking)
2377                          */
2378                         if (tls_has_buffered_record(tls))
2379                                 goto read_record;
2380                 }
2381         }
2382 }