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
  10 //kbuild:lib-$(CONFIG_TLS) += tls.o
  11 //kbuild:lib-$(CONFIG_TLS) += tls_pstm.o
  12 //kbuild:lib-$(CONFIG_TLS) += tls_pstm_montgomery_reduce.o
  13 //kbuild:lib-$(CONFIG_TLS) += tls_pstm_mul_comba.o
  14 //kbuild:lib-$(CONFIG_TLS) += tls_pstm_sqr_comba.o
  15 //kbuild:lib-$(CONFIG_TLS) += tls_aes.o
  16 //kbuild:lib-$(CONFIG_TLS) += tls_rsa.o
  17 //kbuild:lib-$(CONFIG_TLS) += tls_fe.o
  18 ////kbuild:lib-$(CONFIG_TLS) += tls_aes_gcm.o
  19
  20 #include "tls.h"
  21
  22 //Tested against kernel.org:
  23 //TLS 1.2
  24 #define TLS_MAJ 3
  25 #define TLS_MIN 3
  26 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE *** matrixssl uses this on my box
  27 //#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE
  28 //#define CIPHER_ID TLS_DH_anon_WITH_AES_256_CBC_SHA // SSL_ALERT_HANDSHAKE_FAILURE
  29 //^^^^^^^^^^^^^^^^^^^^^^^ (tested b/c this one doesn't req server certs... no luck, server refuses it)
  30 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 // SSL_ALERT_HANDSHAKE_FAILURE
  31 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  32 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 // ok, recvs SERVER_KEY_EXCHANGE
  33 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
  34 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384
  35 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  36 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
  37 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  38 //#define CIPHER_ID TLS_RSA_WITH_AES_256_GCM_SHA384 // ok, no SERVER_KEY_EXCHANGE
  39 //#define CIPHER_ID TLS_RSA_WITH_AES_128_GCM_SHA256 // ok, no SERVER_KEY_EXCHANGE *** select this?
  40
  41 // works against "openssl s_server -cipher NULL"
  42 // and against wolfssl-3.9.10-stable/examples/server/server.c:
  43 //#define CIPHER_ID1 TLS_RSA_WITH_NULL_SHA256 // for testing (does everything except encrypting)
  44
  45 // works against wolfssl-3.9.10-stable/examples/server/server.c
  46 // works for kernel.org
  47 // does not work for cdn.kernel.org (e.g. downloading an actual tarball, not a web page)
  48 //  getting alert 40 "handshake failure" at once
  49 //  with GNU Wget 1.18, they agree on TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xC02F) cipher
  50 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-SHA256
  51 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-GCM-SHA384
  52 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA256
  53 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-GCM-SHA256
  54 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA
  55 //        (TLS_RSA_WITH_AES_128_CBC_SHA - in TLS 1.2 it's mandated to be always supported)
  56 #define CIPHER_ID1  TLS_RSA_WITH_AES_256_CBC_SHA256 // no SERVER_KEY_EXCHANGE from peer
  57 // Works with "wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.9.5.tar.xz"
  58 #define CIPHER_ID2  TLS_RSA_WITH_AES_128_CBC_SHA
  59
  60 // bug #11456: host is.gd accepts only ECDHE-ECDSA-foo (the simplest which works: ECDHE-ECDSA-AES128-SHA 0xC009)
  61 #define CIPHER_ID3  TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
  62
  63
  64 #define TLS_DEBUG      0
  65 #define TLS_DEBUG_HASH 0
  66 #define TLS_DEBUG_DER  0
  67 #define TLS_DEBUG_FIXED_SECRETS 0
  68 #if 0
  69 # define dump_raw_out(...) dump_hex(__VA_ARGS__)
  70 #else
  71 # define dump_raw_out(...) ((void)0)
  72 #endif
  73 #if 0
  74 # define dump_raw_in(...) dump_hex(__VA_ARGS__)
  75 #else
  76 # define dump_raw_in(...) ((void)0)
  77 #endif
  78
  79 #if TLS_DEBUG
  80 # define dbg(...) fprintf(stderr, __VA_ARGS__)
  81 #else
  82 # define dbg(...) ((void)0)
  83 #endif
  84
  85 #if TLS_DEBUG_DER
  86 # define dbg_der(...) fprintf(stderr, __VA_ARGS__)
  87 #else
  88 # define dbg_der(...) ((void)0)
  89 #endif
  90
  91 #define RECORD_TYPE_CHANGE_CIPHER_SPEC  20 /* 0x14 */
  92 #define RECORD_TYPE_ALERT               21 /* 0x15 */
  93 #define RECORD_TYPE_HANDSHAKE           22 /* 0x16 */
  94 #define RECORD_TYPE_APPLICATION_DATA    23 /* 0x17 */
  95
  96 #define HANDSHAKE_HELLO_REQUEST         0  /* 0x00 */
  97 #define HANDSHAKE_CLIENT_HELLO          1  /* 0x01 */
  98 #define HANDSHAKE_SERVER_HELLO          2  /* 0x02 */
  99 #define HANDSHAKE_HELLO_VERIFY_REQUEST  3  /* 0x03 */
 100 #define HANDSHAKE_NEW_SESSION_TICKET    4  /* 0x04 */
 101 #define HANDSHAKE_CERTIFICATE           11 /* 0x0b */
 102 #define HANDSHAKE_SERVER_KEY_EXCHANGE   12 /* 0x0c */
 103 #define HANDSHAKE_CERTIFICATE_REQUEST   13 /* 0x0d */
 104 #define HANDSHAKE_SERVER_HELLO_DONE     14 /* 0x0e */
 105 #define HANDSHAKE_CERTIFICATE_VERIFY    15 /* 0x0f */
 106 #define HANDSHAKE_CLIENT_KEY_EXCHANGE   16 /* 0x10 */
 107 #define HANDSHAKE_FINISHED              20 /* 0x14 */
 108
 109 #define TLS_EMPTY_RENEGOTIATION_INFO_SCSV       0x00FF /* not a real cipher id... */
 110
 111 #define SSL_NULL_WITH_NULL_NULL                 0x0000
 112 #define SSL_RSA_WITH_NULL_MD5                   0x0001
 113 #define SSL_RSA_WITH_NULL_SHA                   0x0002
 114 #define SSL_RSA_WITH_RC4_128_MD5                0x0004
 115 #define SSL_RSA_WITH_RC4_128_SHA                0x0005
 116 #define TLS_RSA_WITH_IDEA_CBC_SHA               0x0007  /* 7 */
 117 #define SSL_RSA_WITH_3DES_EDE_CBC_SHA           0x000A  /* 10 */
 118
 119 #define SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA       0x0016  /* 22 */
 120 #define SSL_DH_anon_WITH_RC4_128_MD5            0x0018  /* 24 */
 121 #define SSL_DH_anon_WITH_3DES_EDE_CBC_SHA       0x001B  /* 27 */
 122 #define TLS_RSA_WITH_AES_128_CBC_SHA            0x002F  /*SSLv3   Kx=RSA   Au=RSA   Enc=AES(128) Mac=SHA1 */
 123 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA        0x0033  /* 51 */
 124 #define TLS_DH_anon_WITH_AES_128_CBC_SHA        0x0034  /* 52 */
 125 #define TLS_RSA_WITH_AES_256_CBC_SHA            0x0035  /* 53 */
 126 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA        0x0039  /* 57 */
 127 #define TLS_DH_anon_WITH_AES_256_CBC_SHA        0x003A  /* 58 */
 128 #define TLS_RSA_WITH_NULL_SHA256                0x003B  /* 59 */
 129 #define TLS_RSA_WITH_AES_128_CBC_SHA256         0x003C  /* 60 */
 130 #define TLS_RSA_WITH_AES_256_CBC_SHA256         0x003D  /* 61 */
 131 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256     0x0067  /* 103 */
 132 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256     0x006B  /* 107 */
 133 #define TLS_PSK_WITH_AES_128_CBC_SHA            0x008C  /* 140 */
 134 #define TLS_PSK_WITH_AES_256_CBC_SHA            0x008D  /* 141 */
 135 #define TLS_DHE_PSK_WITH_AES_128_CBC_SHA        0x0090  /* 144 */
 136 #define TLS_DHE_PSK_WITH_AES_256_CBC_SHA        0x0091  /* 145 */
 137 #define TLS_RSA_WITH_SEED_CBC_SHA               0x0096  /* 150 */
 138 #define TLS_PSK_WITH_AES_128_CBC_SHA256         0x00AE  /* 174 */
 139 #define TLS_PSK_WITH_AES_256_CBC_SHA384         0x00AF  /* 175 */
 140 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA     0xC004  /* 49156 */
 141 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA     0xC005  /* 49157 */
 142 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA    0xC009  /*TLSv1   Kx=ECDH  Au=ECDSA Enc=AES(128) Mac=SHA1 */
 143 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA    0xC00A  /*TLSv1   Kx=ECDH  Au=ECDSA Enc=AES(256) Mac=SHA1 */
 144 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA       0xC00E  /* 49166 */
 145 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA       0xC00F  /* 49167 */
 146 #define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA     0xC012  /* 49170 */
 147 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA      0xC013  /*TLSv1   Kx=ECDH  Au=RSA   Enc=AES(128) Mac=SHA1 */
 148 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA      0xC014  /*TLSv1   Kx=ECDH  Au=RSA   Enc=AES(256) Mac=SHA1 */
 149 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 0xC023  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AES(128) Mac=SHA256 */
 150 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AES(256) Mac=SHA384 */
 151 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256  0xC025  /* 49189 */
 152 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384  0xC026  /* 49190 */
 153 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256   0xC027  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AES(128) Mac=SHA256 */
 154 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384   0xC028  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AES(256) Mac=SHA384 */
 155 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256    0xC029  /* 49193 */
 156 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384    0xC02A  /* 49194 */
 157
 158 /* RFC 5288 "AES Galois Counter Mode (GCM) Cipher Suites for TLS" */
 159 #define TLS_RSA_WITH_AES_128_GCM_SHA256         0x009C  /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESGCM(128) Mac=AEAD */
 160 #define TLS_RSA_WITH_AES_256_GCM_SHA384         0x009D  /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESGCM(256) Mac=AEAD */
 161 #define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESGCM(128) Mac=AEAD */
 162 #define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C  /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESGCM(256) Mac=AEAD */
 163 #define TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256  0xC02D  /* 49197 */
 164 #define TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384  0xC02E  /* 49198 */
 165 #define TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256   0xC02F  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AESGCM(128) Mac=AEAD */
 166 #define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384   0xC030  /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=AESGCM(256) Mac=AEAD */
 167 #define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256    0xC031  /* 49201 */
 168 #define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384    0xC032  /* 49202 */
 169
 170 /* From http://wiki.mozilla.org/Security/Server_Side_TLS */
 171 /* and 'openssl ciphers -V -stdname' */
 172 #define TLS_RSA_WITH_ARIA_128_GCM_SHA256              0xC050 /*TLSv1.2 Kx=RSA   Au=RSA   Enc=ARIAGCM(128) Mac=AEAD */
 173 #define TLS_RSA_WITH_ARIA_256_GCM_SHA384              0xC051 /*TLSv1.2 Kx=RSA   Au=RSA   Enc=ARIAGCM(256) Mac=AEAD */
 174 #define TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256          0xC052 /*TLSv1.2 Kx=DH    Au=RSA   Enc=ARIAGCM(128) Mac=AEAD */
 175 #define TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384          0xC053 /*TLSv1.2 Kx=DH    Au=RSA   Enc=ARIAGCM(256) Mac=AEAD */
 176 #define TLS_ECDHE_ECDSA_WITH_ARIA_128_GCM_SHA256      0xC05C /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=ARIAGCM(128) Mac=AEAD */
 177 #define TLS_ECDHE_ECDSA_WITH_ARIA_256_GCM_SHA384      0xC05D /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=ARIAGCM(256) Mac=AEAD */
 178 #define TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256        0xC060 /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=ARIAGCM(128) Mac=AEAD */
 179 #define TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384        0xC061 /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=ARIAGCM(256) Mac=AEAD */
 180 #define TLS_RSA_WITH_AES_128_CCM                      0xC09C /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM(128) Mac=AEAD */
 181 #define TLS_RSA_WITH_AES_256_CCM                      0xC09D /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM(256) Mac=AEAD */
 182 #define TLS_DHE_RSA_WITH_AES_128_CCM                  0xC09E /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM(128) Mac=AEAD */
 183 #define TLS_DHE_RSA_WITH_AES_256_CCM                  0xC09F /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM(256) Mac=AEAD */
 184 #define TLS_RSA_WITH_AES_128_CCM_8                    0xC0A0 /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM8(128) Mac=AEAD */
 185 #define TLS_RSA_WITH_AES_256_CCM_8                    0xC0A1 /*TLSv1.2 Kx=RSA   Au=RSA   Enc=AESCCM8(256) Mac=AEAD */
 186 #define TLS_DHE_RSA_WITH_AES_128_CCM_8                0xC0A2 /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM8(128) Mac=AEAD */
 187 #define TLS_DHE_RSA_WITH_AES_256_CCM_8                0xC0A3 /*TLSv1.2 Kx=DH    Au=RSA   Enc=AESCCM8(256) Mac=AEAD */
 188 #define TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   0xCCA8 /*TLSv1.2 Kx=ECDH  Au=RSA   Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 189 #define TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 0xCCA9 /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 190 #define TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256     0xCCAA /*TLSv1.2 Kx=DH    Au=RSA   Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 191 #define TLS_ECDHE_ECDSA_WITH_AES_128_CCM              0xC0AC /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM(128) Mac=AEAD */
 192 #define TLS_ECDHE_ECDSA_WITH_AES_256_CCM              0xC0AD /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM(256) Mac=AEAD */
 193 #define TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8            0xC0AE /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM8(128) Mac=AEAD */
 194 #define TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8            0xC0AF /*TLSv1.2 Kx=ECDH  Au=ECDSA Enc=AESCCM8(256) Mac=AEAD */
 195
 196 #define TLS_AES_128_GCM_SHA256                        0x1301 /*TLSv1.3 Kx=any   Au=any   Enc=AESGCM(128) Mac=AEAD */
 197 #define TLS_AES_256_GCM_SHA384                        0x1302 /*TLSv1.3 Kx=any   Au=any   Enc=AESGCM(256) Mac=AEAD */
 198 #define TLS_CHACHA20_POLY1305_SHA256                  0x1303 /*TLSv1.3 Kx=any   Au=any   Enc=CHACHA20/POLY1305(256) Mac=AEAD */
 199 #define TLS_AES_128_CCM_SHA256                        0x1304 /*TLSv1.3 Kx=any   Au=any   Enc=AESCCM(128) Mac=AEAD */
 200
 201 /* Might go to libbb.h */
 202 #define TLS_MAX_CRYPTBLOCK_SIZE 16
 203 #define TLS_MAX_OUTBUF          (1 << 14)
 204
 205 enum {
 206         SHA_INSIZE     = 64,
 207         SHA1_OUTSIZE   = 20,
 208         SHA256_OUTSIZE = 32,
 209
 210         AES_BLOCKSIZE  = 16,
 211         AES128_KEYSIZE = 16,
 212         AES256_KEYSIZE = 32,
 213
 214         RSA_PREMASTER_SIZE = 48,
 215
 216         RECHDR_LEN = 5,
 217
 218         /* 8 = 3+5. 3 extra bytes result in record data being 32-bit aligned */
 219         OUTBUF_PFX = 8 + AES_BLOCKSIZE, /* header + IV */
 220         OUTBUF_SFX = TLS_MAX_MAC_SIZE + TLS_MAX_CRYPTBLOCK_SIZE, /* MAC + padding */
 221
 222         // RFC 5246
 223         // | 6.2.1. Fragmentation
 224         // |  The record layer fragments information blocks into TLSPlaintext
 225         // |  records carrying data in chunks of 2^14 bytes or less.  Client
 226         // |  message boundaries are not preserved in the record layer (i.e.,
 227         // |  multiple client messages of the same ContentType MAY be coalesced
 228         // |  into a single TLSPlaintext record, or a single message MAY be
 229         // |  fragmented across several records)
 230         // |...
 231         // |  length
 232         // |    The length (in bytes) of the following TLSPlaintext.fragment.
 233         // |    The length MUST NOT exceed 2^14.
 234         // |...
 235         // | 6.2.2. Record Compression and Decompression
 236         // |...
 237         // |  Compression must be lossless and may not increase the content length
 238         // |  by more than 1024 bytes.  If the decompression function encounters a
 239         // |  TLSCompressed.fragment that would decompress to a length in excess of
 240         // |  2^14 bytes, it MUST report a fatal decompression failure error.
 241         // |...
 242         // |  length
 243         // |    The length (in bytes) of the following TLSCompressed.fragment.
 244         // |    The length MUST NOT exceed 2^14 + 1024.
 245         // |...
 246         // | 6.2.3.  Record Payload Protection
 247         // |  The encryption and MAC functions translate a TLSCompressed
 248         // |  structure into a TLSCiphertext.  The decryption functions reverse
 249         // |  the process.  The MAC of the record also includes a sequence
 250         // |  number so that missing, extra, or repeated messages are
 251         // |  detectable.
 252         // |...
 253         // |  length
 254         // |    The length (in bytes) of the following TLSCiphertext.fragment.
 255         // |    The length MUST NOT exceed 2^14 + 2048.
 256         MAX_INBUF = RECHDR_LEN + (1 << 14) + 2048,
 257 };
 258
 259 struct record_hdr {
 260         uint8_t type;
 261         uint8_t proto_maj, proto_min;
 262         uint8_t len16_hi, len16_lo;
 263 };
 264
 265 enum {
 266         KEY_ALG_RSA,
 267         KEY_ALG_ECDSA,
 268 };
 269 struct tls_handshake_data {
 270         /* In bbox, md5/sha1/sha256 ctx's are the same structure */
 271         md5sha_ctx_t handshake_hash_ctx;
 272
 273         uint8_t client_and_server_rand32[2 * 32];
 274         uint8_t master_secret[48];
 275
 276         smallint key_alg;
 277 //TODO: store just the DER key here, parse/use/delete it when sending client key
 278 //this way it will stay key type agnostic here.
 279         psRsaKey_t server_rsa_pub_key;
 280         uint8_t ecc_pub_key32[32];
 281
 282         unsigned saved_client_hello_size;
 283         uint8_t saved_client_hello[1];
 284 };
 285
 286
 287 static unsigned get24be(const uint8_t *p)
 288 {
 289         return 0x100*(0x100*p[0] + p[1]) + p[2];
 290 }
 291
 292 #if TLS_DEBUG
 293 static void dump_hex(const char *fmt, const void *vp, int len)
 294 {
 295         char hexbuf[32 * 1024 + 4];
 296         const uint8_t *p = vp;
 297
 298         bin2hex(hexbuf, (void*)p, len)[0] = '\0';
 299         dbg(fmt, hexbuf);
 300 }
 301
 302 static void dump_tls_record(const void *vp, int len)
 303 {
 304         const uint8_t *p = vp;
 305
 306         while (len > 0) {
 307                 unsigned xhdr_len;
 308                 if (len < RECHDR_LEN) {
 309                         dump_hex("< |%s|\n", p, len);
 310                         return;
 311                 }
 312                 xhdr_len = 0x100*p[3] + p[4];
 313                 dbg("< hdr_type:%u ver:%u.%u len:%u", p[0], p[1], p[2], xhdr_len);
 314                 p += RECHDR_LEN;
 315                 len -= RECHDR_LEN;
 316                 if (len >= 4 && p[-RECHDR_LEN] == RECORD_TYPE_HANDSHAKE) {
 317                         unsigned len24 = get24be(p + 1);
 318                         dbg(" type:%u len24:%u", p[0], len24);
 319                 }
 320                 if (xhdr_len > len)
 321                         xhdr_len = len;
 322                 dump_hex(" |%s|\n", p, xhdr_len);
 323                 p += xhdr_len;
 324                 len -= xhdr_len;
 325         }
 326 }
 327 #else
 328 # define dump_hex(...) ((void)0)
 329 # define dump_tls_record(...) ((void)0)
 330 #endif
 331
 332 void tls_get_random(void *buf, unsigned len)
 333 {
 334         if (len != open_read_close("/dev/urandom", buf, len))
 335                 xfunc_die();
 336 }
 337
 338 /* Nondestructively see the current hash value */
 339 static unsigned sha_peek(md5sha_ctx_t *ctx, void *buffer)
 340 {
 341         md5sha_ctx_t ctx_copy = *ctx; /* struct copy */
 342         return sha_end(&ctx_copy, buffer);
 343 }
 344
 345 static ALWAYS_INLINE unsigned get_handshake_hash(tls_state_t *tls, void *buffer)
 346 {
 347         return sha_peek(&tls->hsd->handshake_hash_ctx, buffer);
 348 }
 349
 350 #if !TLS_DEBUG_HASH
 351 # define hash_handshake(tls, fmt, buffer, len) \
 352          hash_handshake(tls, buffer, len)
 353 #endif
 354 static void hash_handshake(tls_state_t *tls, const char *fmt, const void *buffer, unsigned len)
 355 {
 356         md5sha_hash(&tls->hsd->handshake_hash_ctx, buffer, len);
 357 #if TLS_DEBUG_HASH
 358         {
 359                 uint8_t h[TLS_MAX_MAC_SIZE];
 360                 dump_hex(fmt, buffer, len);
 361                 dbg(" (%u bytes) ", (int)len);
 362                 len = sha_peek(&tls->hsd->handshake_hash_ctx, h);
 363                 if (len == SHA1_OUTSIZE)
 364                         dump_hex("sha1:%s\n", h, len);
 365                 else
 366                 if (len == SHA256_OUTSIZE)
 367                         dump_hex("sha256:%s\n", h, len);
 368                 else
 369                         dump_hex("sha???:%s\n", h, len);
 370         }
 371 #endif
 372 }
 373
 374 // RFC 2104
 375 // HMAC(key, text) based on a hash H (say, sha256) is:
 376 // ipad = [0x36 x INSIZE]
 377 // opad = [0x5c x INSIZE]
 378 // HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text))
 379 //
 380 // H(key XOR opad) and H(key XOR ipad) can be precomputed
 381 // if we often need HMAC hmac with the same key.
 382 //
 383 // text is often given in disjoint pieces.
 384 typedef struct hmac_precomputed {
 385         md5sha_ctx_t hashed_key_xor_ipad;
 386         md5sha_ctx_t hashed_key_xor_opad;
 387 } hmac_precomputed_t;
 388
 389 static unsigned hmac_sha_precomputed_v(
 390                 hmac_precomputed_t *pre,
 391                 uint8_t *out,
 392                 va_list va)
 393 {
 394         uint8_t *text;
 395         unsigned len;
 396
 397         /* pre->hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
 398         /* pre->hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
 399
 400         /* calculate out = H((key XOR ipad) + text) */
 401         while ((text = va_arg(va, uint8_t*)) != NULL) {
 402                 unsigned text_size = va_arg(va, unsigned);
 403                 md5sha_hash(&pre->hashed_key_xor_ipad, text, text_size);
 404         }
 405         len = sha_end(&pre->hashed_key_xor_ipad, out);
 406
 407         /* out = H((key XOR opad) + out) */
 408         md5sha_hash(&pre->hashed_key_xor_opad, out, len);
 409         return sha_end(&pre->hashed_key_xor_opad, out);
 410 }
 411
 412 typedef void md5sha_begin_func(md5sha_ctx_t *ctx) FAST_FUNC;
 413 static void hmac_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size, md5sha_begin_func *begin)
 414 {
 415         uint8_t key_xor_ipad[SHA_INSIZE];
 416         uint8_t key_xor_opad[SHA_INSIZE];
 417         uint8_t tempkey[SHA1_OUTSIZE < SHA256_OUTSIZE ? SHA256_OUTSIZE : SHA1_OUTSIZE];
 418         unsigned i;
 419
 420         // "The authentication key can be of any length up to INSIZE, the
 421         // block length of the hash function.  Applications that use keys longer
 422         // than INSIZE bytes will first hash the key using H and then use the
 423         // resultant OUTSIZE byte string as the actual key to HMAC."
 424         if (key_size > SHA_INSIZE) {
 425                 md5sha_ctx_t ctx;
 426                 begin(&ctx);
 427                 md5sha_hash(&ctx, key, key_size);
 428                 key_size = sha_end(&ctx, tempkey);
 429         }
 430
 431         for (i = 0; i < key_size; i++) {
 432                 key_xor_ipad[i] = key[i] ^ 0x36;
 433                 key_xor_opad[i] = key[i] ^ 0x5c;
 434         }
 435         for (; i < SHA_INSIZE; i++) {
 436                 key_xor_ipad[i] = 0x36;
 437                 key_xor_opad[i] = 0x5c;
 438         }
 439
 440         begin(&pre->hashed_key_xor_ipad);
 441         begin(&pre->hashed_key_xor_opad);
 442         md5sha_hash(&pre->hashed_key_xor_ipad, key_xor_ipad, SHA_INSIZE);
 443         md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
 444 }
 445
 446 static unsigned hmac(tls_state_t *tls, uint8_t *out, uint8_t *key, unsigned key_size, ...)
 447 {
 448         hmac_precomputed_t pre;
 449         va_list va;
 450         unsigned len;
 451
 452         va_start(va, key_size);
 453
 454         hmac_begin(&pre, key, key_size,
 455                         (tls->MAC_size == SHA256_OUTSIZE)
 456                                 ? sha256_begin
 457                                 : sha1_begin
 458         );
 459         len = hmac_sha_precomputed_v(&pre, out, va);
 460
 461         va_end(va);
 462         return len;
 463 }
 464
 465 static unsigned hmac_sha256(/*tls_state_t *tls,*/ uint8_t *out, uint8_t *key, unsigned key_size, ...)
 466 {
 467         hmac_precomputed_t pre;
 468         va_list va;
 469         unsigned len;
 470
 471         va_start(va, key_size);
 472
 473         hmac_begin(&pre, key, key_size, sha256_begin);
 474         len = hmac_sha_precomputed_v(&pre, out, va);
 475
 476         va_end(va);
 477         return len;
 478 }
 479
 480 // RFC 5246:
 481 // 5.  HMAC and the Pseudorandom Function
 482 //...
 483 // In this section, we define one PRF, based on HMAC.  This PRF with the
 484 // SHA-256 hash function is used for all cipher suites defined in this
 485 // document and in TLS documents published prior to this document when
 486 // TLS 1.2 is negotiated.
 487 // ^^^^^^^^^^^^^ IMPORTANT!
 488 //               PRF uses sha256 regardless of cipher (at least for all ciphers
 489 //               defined by RFC5246). It's not sha1 for AES_128_CBC_SHA!
 490 //...
 491 //    P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
 492 //                           HMAC_hash(secret, A(2) + seed) +
 493 //                           HMAC_hash(secret, A(3) + seed) + ...
 494 // where + indicates concatenation.
 495 // A() is defined as:
 496 //    A(0) = seed
 497 //    A(1) = HMAC_hash(secret, A(0)) = HMAC_hash(secret, seed)
 498 //    A(i) = HMAC_hash(secret, A(i-1))
 499 // P_hash can be iterated as many times as necessary to produce the
 500 // required quantity of data.  For example, if P_SHA256 is being used to
 501 // create 80 bytes of data, it will have to be iterated three times
 502 // (through A(3)), creating 96 bytes of output data; the last 16 bytes
 503 // of the final iteration will then be discarded, leaving 80 bytes of
 504 // output data.
 505 //
 506 // TLS's PRF is created by applying P_hash to the secret as:
 507 //
 508 //    PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 509 //
 510 // The label is an ASCII string.
 511 static void prf_hmac_sha256(/*tls_state_t *tls,*/
 512                 uint8_t *outbuf, unsigned outbuf_size,
 513                 uint8_t *secret, unsigned secret_size,
 514                 const char *label,
 515                 uint8_t *seed, unsigned seed_size)
 516 {
 517         uint8_t a[TLS_MAX_MAC_SIZE];
 518         uint8_t *out_p = outbuf;
 519         unsigned label_size = strlen(label);
 520         unsigned MAC_size = SHA256_OUTSIZE;
 521
 522         /* In P_hash() calculation, "seed" is "label + seed": */
 523 #define SEED   label, label_size, seed, seed_size
 524 #define SECRET secret, secret_size
 525 #define A      a, MAC_size
 526
 527         /* A(1) = HMAC_hash(secret, seed) */
 528         hmac_sha256(/*tls,*/ a, SECRET, SEED, NULL);
 529 //TODO: convert hmac to precomputed
 530
 531         for (;;) {
 532                 /* HMAC_hash(secret, A(1) + seed) */
 533                 if (outbuf_size <= MAC_size) {
 534                         /* Last, possibly incomplete, block */
 535                         /* (use a[] as temp buffer) */
 536                         hmac_sha256(/*tls,*/ a, SECRET, A, SEED, NULL);
 537                         memcpy(out_p, a, outbuf_size);
 538                         return;
 539                 }
 540                 /* Not last block. Store directly to result buffer */
 541                 hmac_sha256(/*tls,*/ out_p, SECRET, A, SEED, NULL);
 542                 out_p += MAC_size;
 543                 outbuf_size -= MAC_size;
 544                 /* A(2) = HMAC_hash(secret, A(1)) */
 545                 hmac_sha256(/*tls,*/ a, SECRET, A, NULL);
 546         }
 547 #undef A
 548 #undef SECRET
 549 #undef SEED
 550 }
 551
 552 static void bad_record_die(tls_state_t *tls, const char *expected, int len)
 553 {
 554         bb_error_msg("got bad TLS record (len:%d) while expecting %s", len, expected);
 555         if (len > 0) {
 556                 uint8_t *p = tls->inbuf;
 557                 if (len > 99)
 558                         len = 99; /* don't flood, a few lines should be enough */
 559                 do {
 560                         fprintf(stderr, " %02x", *p++);
 561                         len--;
 562                 } while (len != 0);
 563                 fputc('\n', stderr);
 564         }
 565         xfunc_die();
 566 }
 567
 568 static void tls_error_die(tls_state_t *tls, int line)
 569 {
 570         dump_tls_record(tls->inbuf, tls->ofs_to_buffered + tls->buffered_size);
 571         bb_error_msg_and_die("tls error at line %d cipher:%04x", line, tls->cipher_id);
 572 }
 573 #define tls_error_die(tls) tls_error_die(tls, __LINE__)
 574
 575 #if 0 //UNUSED
 576 static void tls_free_inbuf(tls_state_t *tls)
 577 {
 578         if (tls->buffered_size == 0) {
 579                 free(tls->inbuf);
 580                 tls->inbuf_size = 0;
 581                 tls->inbuf = NULL;
 582         }
 583 }
 584 #endif
 585
 586 static void tls_free_outbuf(tls_state_t *tls)
 587 {
 588         free(tls->outbuf);
 589         tls->outbuf_size = 0;
 590         tls->outbuf = NULL;
 591 }
 592
 593 static void *tls_get_outbuf(tls_state_t *tls, int len)
 594 {
 595         if (len > TLS_MAX_OUTBUF)
 596                 xfunc_die();
 597         len += OUTBUF_PFX + OUTBUF_SFX;
 598         if (tls->outbuf_size < len) {
 599                 tls->outbuf_size = len;
 600                 tls->outbuf = xrealloc(tls->outbuf, len);
 601         }
 602         return tls->outbuf + OUTBUF_PFX;
 603 }
 604
 605 static void *tls_get_zeroed_outbuf(tls_state_t *tls, int len)
 606 {
 607         void *record = tls_get_outbuf(tls, len);
 608         memset(record, 0, len);
 609         return record;
 610 }
 611
 612 static void xwrite_encrypted(tls_state_t *tls, unsigned size, unsigned type)
 613 {
 614         uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 615         struct record_hdr *xhdr;
 616         uint8_t padding_length;
 617
 618         xhdr = (void*)(buf - RECHDR_LEN);
 619         if (CIPHER_ID1 != TLS_RSA_WITH_NULL_SHA256 /* if "no encryption" can't be selected */
 620          || tls->cipher_id != TLS_RSA_WITH_NULL_SHA256 /* or if it wasn't selected */
 621         ) {
 622                 xhdr = (void*)(buf - RECHDR_LEN - AES_BLOCKSIZE); /* place for IV */
 623         }
 624
 625         xhdr->type = type;
 626         xhdr->proto_maj = TLS_MAJ;
 627         xhdr->proto_min = TLS_MIN;
 628         /* fake unencrypted record len for MAC calculation */
 629         xhdr->len16_hi = size >> 8;
 630         xhdr->len16_lo = size & 0xff;
 631
 632         /* Calculate MAC signature */
 633         hmac(tls, buf + size, /* result */
 634                 tls->client_write_MAC_key, tls->MAC_size,
 635                 &tls->write_seq64_be, sizeof(tls->write_seq64_be),
 636                 xhdr, RECHDR_LEN,
 637                 buf, size,
 638                 NULL
 639         );
 640         tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
 641
 642         size += tls->MAC_size;
 643
 644         // RFC 5246
 645         // 6.2.3.1.  Null or Standard Stream Cipher
 646         //
 647         // Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6)
 648         // convert TLSCompressed.fragment structures to and from stream
 649         // TLSCiphertext.fragment structures.
 650         //
 651         //    stream-ciphered struct {
 652         //        opaque content[TLSCompressed.length];
 653         //        opaque MAC[SecurityParameters.mac_length];
 654         //    } GenericStreamCipher;
 655         //
 656         // The MAC is generated as:
 657         //    MAC(MAC_write_key, seq_num +
 658         //                          TLSCompressed.type +
 659         //                          TLSCompressed.version +
 660         //                          TLSCompressed.length +
 661         //                          TLSCompressed.fragment);
 662         // where "+" denotes concatenation.
 663         // seq_num
 664         //    The sequence number for this record.
 665         // MAC
 666         //    The MAC algorithm specified by SecurityParameters.mac_algorithm.
 667         //
 668         // Note that the MAC is computed before encryption.  The stream cipher
 669         // encrypts the entire block, including the MAC.
 670         //...
 671         // Appendix C.  Cipher Suite Definitions
 672         //...
 673         // MAC       Algorithm    mac_length  mac_key_length
 674         // --------  -----------  ----------  --------------
 675         // SHA       HMAC-SHA1       20            20
 676         // SHA256    HMAC-SHA256     32            32
 677         if (CIPHER_ID1 == TLS_RSA_WITH_NULL_SHA256
 678          && tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
 679         ) {
 680                 /* No encryption, only signing */
 681                 xhdr->len16_hi = size >> 8;
 682                 xhdr->len16_lo = size & 0xff;
 683                 dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 684                 xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 685                 dbg("wrote %u bytes (NULL crypt, SHA256 hash)\n", size);
 686                 return;
 687         }
 688
 689         // 6.2.3.2.  CBC Block Cipher
 690         // For block ciphers (such as 3DES or AES), the encryption and MAC
 691         // functions convert TLSCompressed.fragment structures to and from block
 692         // TLSCiphertext.fragment structures.
 693         //    struct {
 694         //        opaque IV[SecurityParameters.record_iv_length];
 695         //        block-ciphered struct {
 696         //            opaque content[TLSCompressed.length];
 697         //            opaque MAC[SecurityParameters.mac_length];
 698         //            uint8 padding[GenericBlockCipher.padding_length];
 699         //            uint8 padding_length;
 700         //        };
 701         //    } GenericBlockCipher;
 702         //...
 703         // IV
 704         //    The Initialization Vector (IV) SHOULD be chosen at random, and
 705         //    MUST be unpredictable.  Note that in versions of TLS prior to 1.1,
 706         //    there was no IV field (...).  For block ciphers, the IV length is
 707         //    of length SecurityParameters.record_iv_length, which is equal to the
 708         //    SecurityParameters.block_size.
 709         // padding
 710         //    Padding that is added to force the length of the plaintext to be
 711         //    an integral multiple of the block cipher's block length.
 712         // padding_length
 713         //    The padding length MUST be such that the total size of the
 714         //    GenericBlockCipher structure is a multiple of the cipher's block
 715         //    length.  Legal values range from zero to 255, inclusive.
 716         //...
 717         // Appendix C.  Cipher Suite Definitions
 718         //...
 719         //                         Key      IV   Block
 720         // Cipher        Type    Material  Size  Size
 721         // ------------  ------  --------  ----  -----
 722         // AES_128_CBC   Block      16      16     16
 723         // AES_256_CBC   Block      32      16     16
 724
 725         tls_get_random(buf - AES_BLOCKSIZE, AES_BLOCKSIZE); /* IV */
 726         dbg("before crypt: 5 hdr + %u data + %u hash bytes\n",
 727                         size - tls->MAC_size, tls->MAC_size);
 728
 729         /* Fill IV and padding in outbuf */
 730         // RFC is talking nonsense:
 731         //    "Padding that is added to force the length of the plaintext to be
 732         //    an integral multiple of the block cipher's block length."
 733         // WRONG. _padding+padding_length_, not just _padding_,
 734         // pads the data.
 735         // IOW: padding_length is the last byte of padding[] array,
 736         // contrary to what RFC depicts.
 737         //
 738         // What actually happens is that there is always padding.
 739         // If you need one byte to reach BLOCKSIZE, this byte is 0x00.
 740         // If you need two bytes, they are both 0x01.
 741         // If you need three, they are 0x02,0x02,0x02. And so on.
 742         // If you need no bytes to reach BLOCKSIZE, you have to pad a full
 743         // BLOCKSIZE with bytes of value (BLOCKSIZE-1).
 744         // It's ok to have more than minimum padding, but we do minimum.
 745         padding_length = (~size) & (AES_BLOCKSIZE - 1);
 746         do {
 747                 buf[size++] = padding_length; /* padding */
 748         } while ((size & (AES_BLOCKSIZE - 1)) != 0);
 749
 750         /* Encrypt content+MAC+padding in place */
 751         aes_cbc_encrypt(
 752                 tls->client_write_key, tls->key_size, /* selects 128/256 */
 753                 buf - AES_BLOCKSIZE, /* IV */
 754                 buf, size, /* plaintext */
 755                 buf /* ciphertext */
 756         );
 757
 758         /* Write out */
 759         dbg("writing 5 + %u IV + %u encrypted bytes, padding_length:0x%02x\n",
 760                         AES_BLOCKSIZE, size, padding_length);
 761         size += AES_BLOCKSIZE;     /* + IV */
 762         xhdr->len16_hi = size >> 8;
 763         xhdr->len16_lo = size & 0xff;
 764         dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 765         xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 766         dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 767 }
 768
 769 static void xwrite_handshake_record(tls_state_t *tls, unsigned size)
 770 {
 771         //if (!tls->encrypt_on_write) {
 772                 uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 773                 struct record_hdr *xhdr = (void*)(buf - RECHDR_LEN);
 774
 775                 xhdr->type = RECORD_TYPE_HANDSHAKE;
 776                 xhdr->proto_maj = TLS_MAJ;
 777                 xhdr->proto_min = TLS_MIN;
 778                 xhdr->len16_hi = size >> 8;
 779                 xhdr->len16_lo = size & 0xff;
 780                 dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 781                 xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 782                 dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 783         //      return;
 784         //}
 785         //xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
 786 }
 787
 788 static void xwrite_and_update_handshake_hash(tls_state_t *tls, unsigned size)
 789 {
 790         if (!tls->encrypt_on_write) {
 791                 uint8_t *buf;
 792
 793                 xwrite_handshake_record(tls, size);
 794                 /* Handshake hash does not include record headers */
 795                 buf = tls->outbuf + OUTBUF_PFX;
 796                 hash_handshake(tls, ">> hash:%s", buf, size);
 797                 return;
 798         }
 799         xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
 800 }
 801
 802 static int tls_has_buffered_record(tls_state_t *tls)
 803 {
 804         int buffered = tls->buffered_size;
 805         struct record_hdr *xhdr;
 806         int rec_size;
 807
 808         if (buffered < RECHDR_LEN)
 809                 return 0;
 810         xhdr = (void*)(tls->inbuf + tls->ofs_to_buffered);
 811         rec_size = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
 812         if (buffered < rec_size)
 813                 return 0;
 814         return rec_size;
 815 }
 816
 817 static const char *alert_text(int code)
 818 {
 819         switch (code) {
 820         case 20:  return "bad MAC";
 821         case 50:  return "decode error";
 822         case 51:  return "decrypt error";
 823         case 40:  return "handshake failure";
 824         case 112: return "unrecognized name";
 825         }
 826         return itoa(code);
 827 }
 828
 829 static int tls_xread_record(tls_state_t *tls, const char *expected)
 830 {
 831         struct record_hdr *xhdr;
 832         int sz;
 833         int total;
 834         int target;
 835
 836  again:
 837         dbg("ofs_to_buffered:%u buffered_size:%u\n", tls->ofs_to_buffered, tls->buffered_size);
 838         total = tls->buffered_size;
 839         if (total != 0) {
 840                 memmove(tls->inbuf, tls->inbuf + tls->ofs_to_buffered, total);
 841                 //dbg("<< remaining at %d [%d] ", tls->ofs_to_buffered, total);
 842                 //dump_raw_in("<< %s\n", tls->inbuf, total);
 843         }
 844         errno = 0;
 845         target = MAX_INBUF;
 846         for (;;) {
 847                 int rem;
 848
 849                 if (total >= RECHDR_LEN && target == MAX_INBUF) {
 850                         xhdr = (void*)tls->inbuf;
 851                         target = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
 852
 853                         if (target > MAX_INBUF /* malformed input (too long) */
 854                          || xhdr->proto_maj != TLS_MAJ
 855                          || xhdr->proto_min != TLS_MIN
 856                         ) {
 857                                 sz = total < target ? total : target;
 858                                 bad_record_die(tls, expected, sz);
 859                         }
 860                         dbg("xhdr type:%d ver:%d.%d len:%d\n",
 861                                 xhdr->type, xhdr->proto_maj, xhdr->proto_min,
 862                                 0x100 * xhdr->len16_hi + xhdr->len16_lo
 863                         );
 864                 }
 865                 /* if total >= target, we have a full packet (and possibly more)... */
 866                 if (total - target >= 0)
 867                         break;
 868                 /* input buffer is grown only as needed */
 869                 rem = tls->inbuf_size - total;
 870                 if (rem == 0) {
 871                         tls->inbuf_size += MAX_INBUF / 8;
 872                         if (tls->inbuf_size > MAX_INBUF)
 873                                 tls->inbuf_size = MAX_INBUF;
 874                         dbg("inbuf_size:%d\n", tls->inbuf_size);
 875                         rem = tls->inbuf_size - total;
 876                         tls->inbuf = xrealloc(tls->inbuf, tls->inbuf_size);
 877                 }
 878                 sz = safe_read(tls->ifd, tls->inbuf + total, rem);
 879                 if (sz <= 0) {
 880                         if (sz == 0 && total == 0) {
 881                                 /* "Abrupt" EOF, no TLS shutdown (seen from kernel.org) */
 882                                 dbg("EOF (without TLS shutdown) from peer\n");
 883                                 tls->buffered_size = 0;
 884                                 goto end;
 885                         }
 886                         bb_perror_msg_and_die("short read, have only %d", total);
 887                 }
 888                 dump_raw_in("<< %s\n", tls->inbuf + total, sz);
 889                 total += sz;
 890         }
 891         tls->buffered_size = total - target;
 892         tls->ofs_to_buffered = target;
 893         //dbg("<< stashing at %d [%d] ", tls->ofs_to_buffered, tls->buffered_size);
 894         //dump_hex("<< %s\n", tls->inbuf + tls->ofs_to_buffered, tls->buffered_size);
 895
 896         sz = target - RECHDR_LEN;
 897
 898         /* Needs to be decrypted? */
 899         if (tls->min_encrypted_len_on_read > tls->MAC_size) {
 900                 uint8_t *p = tls->inbuf + RECHDR_LEN;
 901                 int padding_len;
 902
 903                 if (sz & (AES_BLOCKSIZE-1)
 904                  || sz < (int)tls->min_encrypted_len_on_read
 905                 ) {
 906                         bb_error_msg_and_die("bad encrypted len:%u < %u",
 907                                 sz, tls->min_encrypted_len_on_read);
 908                 }
 909                 /* Decrypt content+MAC+padding, moving it over IV in the process */
 910                 sz -= AES_BLOCKSIZE; /* we will overwrite IV now */
 911                 aes_cbc_decrypt(
 912                         tls->server_write_key, tls->key_size, /* selects 128/256 */
 913                         p, /* IV */
 914                         p + AES_BLOCKSIZE, sz, /* ciphertext */
 915                         p /* plaintext */
 916                 );
 917                 padding_len = p[sz - 1];
 918                 dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[0], padding_len);
 919                 padding_len++;
 920                 sz -= tls->MAC_size + padding_len; /* drop MAC and padding */
 921                 //if (sz < 0)
 922                 //      bb_error_msg_and_die("bad padding size:%u", padding_len);
 923         } else {
 924                 /* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
 925                 /* else: no encryption yet on input, subtract zero = NOP */
 926                 sz -= tls->min_encrypted_len_on_read;
 927         }
 928         if (sz < 0)
 929                 bb_error_msg_and_die("encrypted data too short");
 930
 931         //dump_hex("<< %s\n", tls->inbuf, RECHDR_LEN + sz);
 932
 933         xhdr = (void*)tls->inbuf;
 934         if (xhdr->type == RECORD_TYPE_ALERT && sz >= 2) {
 935                 uint8_t *p = tls->inbuf + RECHDR_LEN;
 936                 dbg("ALERT size:%d level:%d description:%d\n", sz, p[0], p[1]);
 937                 if (p[0] == 2) { /* fatal */
 938                         bb_error_msg_and_die("TLS %s from peer (alert code %d): %s",
 939                                 "error",
 940                                 p[1], alert_text(p[1])
 941                         );
 942                 }
 943                 if (p[0] == 1) { /* warning */
 944                         if (p[1] == 0) { /* "close_notify" warning: it's EOF */
 945                                 dbg("EOF (TLS encoded) from peer\n");
 946                                 sz = 0;
 947                                 goto end;
 948                         }
 949 //This possibly needs to be cached and shown only if
 950 //a fatal alert follows
 951 //                      bb_error_msg("TLS %s from peer (alert code %d): %s",
 952 //                              "warning",
 953 //                              p[1], alert_text(p[1])
 954 //                      );
 955                         /* discard it, get next record */
 956                         goto again;
 957                 }
 958                 /* p[0] not 1 or 2: not defined in protocol */
 959                 sz = 0;
 960                 goto end;
 961         }
 962
 963         /* RFC 5246 is not saying it explicitly, but sha256 hash
 964          * in our FINISHED record must include data of incoming packets too!
 965          */
 966         if (tls->inbuf[0] == RECORD_TYPE_HANDSHAKE
 967          && tls->MAC_size != 0 /* do we know which hash to use? (server_hello() does not!) */
 968         ) {
 969                 hash_handshake(tls, "<< hash:%s", tls->inbuf + RECHDR_LEN, sz);
 970         }
 971  end:
 972         dbg("got block len:%u\n", sz);
 973         return sz;
 974 }
 975
 976 static void binary_to_pstm(pstm_int *pstm_n, uint8_t *bin_ptr, unsigned len)
 977 {
 978         pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len);
 979         pstm_read_unsigned_bin(pstm_n, bin_ptr, len);
 980         //return bin_ptr + len;
 981 }
 982
 983 /*
 984  * DER parsing routines
 985  */
 986 static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end)
 987 {
 988         unsigned len, len1;
 989
 990         if (end - der < 2)
 991                 xfunc_die();
 992 //      if ((der[0] & 0x1f) == 0x1f) /* not single-byte item code? */
 993 //              xfunc_die();
 994
 995         len = der[1]; /* maybe it's short len */
 996         if (len >= 0x80) {
 997                 /* no, it's long */
 998
 999                 if (len == 0x80 || end - der < (int)(len - 0x7e)) {
1000                         /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */
1001                         /* need 3 or 4 bytes for 81, 82 */
1002                         xfunc_die();
1003                 }
1004
1005                 len1 = der[2]; /* if (len == 0x81) it's "ii 81 xx", fetch xx */
1006                 if (len > 0x82) {
1007                         /* >0x82 is "3+ bytes of len", should not happen realistically */
1008                         xfunc_die();
1009                 }
1010                 if (len == 0x82) { /* it's "ii 82 xx yy" */
1011                         len1 = 0x100*len1 + der[3];
1012                         der += 1; /* skip [yy] */
1013                 }
1014                 der += 1; /* skip [xx] */
1015                 len = len1;
1016 //              if (len < 0x80)
1017 //                      xfunc_die(); /* invalid DER: must use short len if can */
1018         }
1019         der += 2; /* skip [code]+[1byte] */
1020
1021         if (end - der < (int)len)
1022                 xfunc_die();
1023         *bodyp = der;
1024
1025         return len;
1026 }
1027
1028 static uint8_t *enter_der_item(uint8_t *der, uint8_t **endp)
1029 {
1030         uint8_t *new_der;
1031         unsigned len = get_der_len(&new_der, der, *endp);
1032         dbg_der("entered der @%p:0x%02x len:%u inner_byte @%p:0x%02x\n", der, der[0], len, new_der, new_der[0]);
1033         /* Move "end" position to cover only this item */
1034         *endp = new_der + len;
1035         return new_der;
1036 }
1037
1038 static uint8_t *skip_der_item(uint8_t *der, uint8_t *end)
1039 {
1040         uint8_t *new_der;
1041         unsigned len = get_der_len(&new_der, der, end);
1042         /* Skip body */
1043         new_der += len;
1044         dbg_der("skipped der 0x%02x, next byte 0x%02x\n", der[0], new_der[0]);
1045         return new_der;
1046 }
1047
1048 static void der_binary_to_pstm(pstm_int *pstm_n, uint8_t *der, uint8_t *end)
1049 {
1050         uint8_t *bin_ptr;
1051         unsigned len = get_der_len(&bin_ptr, der, end);
1052
1053         dbg_der("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]);
1054         binary_to_pstm(pstm_n, bin_ptr, len);
1055 }
1056
1057 static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len)
1058 {
1059 /* Certificate is a DER-encoded data structure. Each DER element has a length,
1060  * which makes it easy to skip over large compound elements of any complexity
1061  * without parsing them. Example: partial decode of kernel.org certificate:
1062  *  SEQ 0x05ac/1452 bytes (Certificate): 308205ac
1063  *    SEQ 0x0494/1172 bytes (tbsCertificate): 30820494
1064  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0] 3 bytes: a003
1065  *        INTEGER (version): 0201 02
1066  *      INTEGER 0x11 bytes (serialNumber): 0211 00 9f85bf664b0cddafca508679501b2be4
1067  *      //^^^^^^note: matrixSSL also allows [ASN_CONTEXT_SPECIFIC | ASN_PRIMITIVE | 2] = 0x82 type
1068  *      SEQ 0x0d bytes (signatureAlgo): 300d
1069  *        OID 9 bytes: 0609 2a864886f70d01010b (OID_SHA256_RSA_SIG 42.134.72.134.247.13.1.1.11)
1070  *        NULL: 0500
1071  *      SEQ 0x5f bytes (issuer): 305f
1072  *        SET 11 bytes: 310b
1073  *          SEQ 9 bytes: 3009
1074  *            OID 3 bytes: 0603 550406
1075  *            Printable string "FR": 1302 4652
1076  *        SET 14 bytes: 310e
1077  *          SEQ 12 bytes: 300c
1078  *            OID 3 bytes: 0603 550408
1079  *            Printable string "Paris": 1305 5061726973
1080  *        SET 14 bytes: 310e
1081  *          SEQ 12 bytes: 300c
1082  *            OID 3 bytes: 0603 550407
1083  *            Printable string "Paris": 1305 5061726973
1084  *        SET 14 bytes: 310e
1085  *          SEQ 12 bytes: 300c
1086  *            OID 3 bytes: 0603 55040a
1087  *            Printable string "Gandi": 1305 47616e6469
1088  *        SET 32 bytes: 3120
1089  *          SEQ 30 bytes: 301e
1090  *            OID 3 bytes: 0603 550403
1091  *            Printable string "Gandi Standard SSL CA 2": 1317 47616e6469205374616e646172642053534c2043412032
1092  *      SEQ 30 bytes (validity): 301e
1093  *        TIME "161011000000Z": 170d 3136313031313030303030305a
1094  *        TIME "191011235959Z": 170d 3139313031313233353935395a
1095  *      SEQ 0x5b/91 bytes (subject): 305b //I did not decode this
1096  *          3121301f060355040b1318446f6d61696e20436f
1097  *          6e74726f6c2056616c6964617465643121301f06
1098  *          0355040b1318506f73697469766553534c204d75
1099  *          6c74692d446f6d61696e31133011060355040313
1100  *          0a6b65726e656c2e6f7267
1101  *      SEQ 0x01a2/418 bytes (subjectPublicKeyInfo): 308201a2
1102  *        SEQ 13 bytes (algorithm): 300d
1103  *          OID 9 bytes: 0609 2a864886f70d010101 (OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1)
1104  *          NULL: 0500
1105  *        BITSTRING 0x018f/399 bytes (publicKey): 0382018f
1106  *          ????: 00
1107  *          //after the zero byte, it appears key itself uses DER encoding:
1108  *          SEQ 0x018a/394 bytes: 3082018a
1109  *            INTEGER 0x0181/385 bytes (modulus): 02820181
1110  *                  00b1ab2fc727a3bef76780c9349bf3
1111  *                  ...24 more blocks of 15 bytes each...
1112  *                  90e895291c6bc8693b65
1113  *            INTEGER 3 bytes (exponent): 0203 010001
1114  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0x3] 0x01e5 bytes (X509v3 extensions): a38201e5
1115  *        SEQ 0x01e1 bytes: 308201e1
1116  *        ...
1117  * Certificate is a sequence of three elements:
1118  *      tbsCertificate (SEQ)
1119  *      signatureAlgorithm (AlgorithmIdentifier)
1120  *      signatureValue (BIT STRING)
1121  *
1122  * In turn, tbsCertificate is a sequence of:
1123  *      version
1124  *      serialNumber
1125  *      signatureAlgo (AlgorithmIdentifier)
1126  *      issuer (Name, has complex structure)
1127  *      validity (Validity, SEQ of two Times)
1128  *      subject (Name)
1129  *      subjectPublicKeyInfo (SEQ)
1130  *      ...
1131  *
1132  * subjectPublicKeyInfo is a sequence of:
1133  *      algorithm (AlgorithmIdentifier)
1134  *      publicKey (BIT STRING)
1135  *
1136  * We need Certificate.tbsCertificate.subjectPublicKeyInfo.publicKey
1137  *
1138  * Example of an ECDSA key:
1139  *      SEQ 0x59 bytes (subjectPublicKeyInfo): 3059
1140  *        SEQ 0x13 bytes (algorithm): 3013
1141  *          OID 7 bytes: 0607 2a8648ce3d0201   (OID_ECDSA_KEY_ALG 42.134.72.206.61.2.1)
1142  *          OID 8 bytes: 0608 2a8648ce3d030107 (OID_EC_prime256v1 42.134.72.206.61.3.1.7)
1143  *        BITSTRING 0x42 bytes (publicKey): 0342
1144  *          0004 53af f65e 50cc 7959 7e29 0171 c75c
1145  *          7335 e07d f45b 9750 b797 3a38 aebb 2ac6
1146  *          8329 2748 e77e 41cb d482 2ce6 05ec a058
1147  *          f3ab d561 2f4c d845 9ad3 7252 e3de bd3b
1148  *          9012
1149  */
1150         uint8_t *end = der + len;
1151
1152         /* enter "Certificate" item: [der, end) will be only Cert */
1153         der = enter_der_item(der, &end);
1154
1155         /* enter "tbsCertificate" item: [der, end) will be only tbsCert */
1156         der = enter_der_item(der, &end);
1157
1158         /*
1159          * Skip version field only if it is present. For a v1 certificate, the
1160          * version field won't be present since v1 is the default value for the
1161          * version field and fields with default values should be omitted (see
1162          * RFC 5280 sections 4.1 and 4.1.2.1). If the version field is present
1163          * it will have a tag class of 2 (context-specific), bit 6 as 1
1164          * (constructed), and a tag number of 0 (see ITU-T X.690 sections 8.1.2
1165          * and 8.14).
1166          */
1167         /* bits 7-6: 10 */
1168         /* bit 5: 1 */
1169         /* bits 4-0: 00000 */
1170         if (der[0] == 0xa0)
1171                 der = skip_der_item(der, end); /* version */
1172
1173         /* skip up to subjectPublicKeyInfo */
1174         der = skip_der_item(der, end); /* serialNumber */
1175         der = skip_der_item(der, end); /* signatureAlgo */
1176         der = skip_der_item(der, end); /* issuer */
1177         der = skip_der_item(der, end); /* validity */
1178         der = skip_der_item(der, end); /* subject */
1179
1180         /* enter subjectPublicKeyInfo */
1181         der = enter_der_item(der, &end);
1182         { /* check subjectPublicKeyInfo.algorithm */
1183                 static const uint8_t OID_RSA_KEY_ALG[] = {
1184                         0x30,0x0d, // SEQ 13 bytes
1185                         0x06,0x09, 0x2a,0x86,0x48,0x86,0xf7,0x0d,0x01,0x01,0x01, //OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1
1186                         //0x05,0x00, // NULL
1187                 };
1188                 static const uint8_t OID_ECDSA_KEY_ALG[] = {
1189                         0x30,0x13, // SEQ 0x13 bytes
1190                         0x06,0x07, 0x2a,0x86,0x48,0xce,0x3d,0x02,0x01,      //OID_ECDSA_KEY_ALG 42.134.72.206.61.2.1
1191                 //allow any curve code for now...
1192                 //      0x06,0x08, 0x2a,0x86,0x48,0xce,0x3d,0x03,0x01,0x07, //OID_EC_prime256v1 42.134.72.206.61.3.1.7
1193                         //RFC 3279:
1194                         //42.134.72.206.61.3     is ellipticCurve
1195                         //42.134.72.206.61.3.0   is c-TwoCurve
1196                         //42.134.72.206.61.3.1   is primeCurve
1197                         //42.134.72.206.61.3.1.7 is curve_secp256r1
1198                 };
1199                 if (memcmp(der, OID_RSA_KEY_ALG, sizeof(OID_RSA_KEY_ALG)) == 0) {
1200                         dbg("RSA key\n");
1201                         tls->hsd->key_alg = KEY_ALG_RSA;
1202                 } else
1203                 if (memcmp(der, OID_ECDSA_KEY_ALG, sizeof(OID_ECDSA_KEY_ALG)) == 0) {
1204                         dbg("ECDSA key\n");
1205                         tls->hsd->key_alg = KEY_ALG_ECDSA;
1206                 } else
1207                         bb_error_msg_and_die("not RSA or ECDSA key");
1208         }
1209
1210         if (tls->hsd->key_alg == KEY_ALG_RSA) {
1211                 /* parse RSA key: */
1212         //based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note
1213                 /* skip subjectPublicKeyInfo.algorithm */
1214                 der = skip_der_item(der, end);
1215                 /* enter subjectPublicKeyInfo.publicKey */
1216                 //die_if_not_this_der_type(der, end, 0x03); /* must be BITSTRING */
1217                 der = enter_der_item(der, &end);
1218
1219                 dbg("key bytes:%u, first:0x%02x\n", (int)(end - der), der[0]);
1220                 if (end - der < 14)
1221                         xfunc_die();
1222                 /* example format:
1223                  * ignore bits: 00
1224                  * SEQ 0x018a/394 bytes: 3082018a
1225                  *   INTEGER 0x0181/385 bytes (modulus): 02820181 XX...XXX
1226                  *   INTEGER 3 bytes (exponent): 0203 010001
1227                  */
1228                 if (*der != 0) /* "ignore bits", should be 0 */
1229                         xfunc_die();
1230                 der++;
1231                 der = enter_der_item(der, &end); /* enter SEQ */
1232                 /* memset(tls->hsd->server_rsa_pub_key, 0, sizeof(tls->hsd->server_rsa_pub_key)); - already is */
1233                 der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.N, der, end); /* modulus */
1234                 der = skip_der_item(der, end);
1235                 der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.e, der, end); /* exponent */
1236                 tls->hsd->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->hsd->server_rsa_pub_key.N);
1237                 dbg("server_rsa_pub_key.size:%d\n", tls->hsd->server_rsa_pub_key.size);
1238         }
1239         /* else: ECDSA key. It is not used for generating encryption keys,
1240          * it is used only to sign the EC public key (which comes in ServerKey message).
1241          * Since we do not verify cert validity, verifying signature on EC public key
1242          * wouldn't add any security. Thus, we do nothing here.
1243          */
1244 }
1245
1246 /*
1247  * TLS Handshake routines
1248  */
1249 static int tls_xread_handshake_block(tls_state_t *tls, int min_len)
1250 {
1251         struct record_hdr *xhdr;
1252         int len = tls_xread_record(tls, "handshake record");
1253
1254         xhdr = (void*)tls->inbuf;
1255         if (len < min_len
1256          || xhdr->type != RECORD_TYPE_HANDSHAKE
1257         ) {
1258                 bad_record_die(tls, "handshake record", len);
1259         }
1260         dbg("got HANDSHAKE\n");
1261         return len;
1262 }
1263
1264 static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, unsigned len)
1265 {
1266         struct handshake_hdr {
1267                 uint8_t type;
1268                 uint8_t len24_hi, len24_mid, len24_lo;
1269         } *h = buf;
1270
1271         len -= 4;
1272         h->type = type;
1273         h->len24_hi  = len >> 16;
1274         h->len24_mid = len >> 8;
1275         h->len24_lo  = len & 0xff;
1276 }
1277
1278 static void send_client_hello_and_alloc_hsd(tls_state_t *tls, const char *sni)
1279 {
1280         static const uint8_t supported_groups[] = {
1281                 0x00,0x0a, //extension_type: "supported_groups"
1282                 0x00,0x04, //ext len
1283                 0x00,0x02, //list len
1284                 0x00,0x1d, //curve_x25519 (rfc7748)
1285                 //0x00,0x17, //curve_secp256r1
1286                 //0x00,0x18, //curve_secp384r1
1287                 //0x00,0x19, //curve_secp521r1
1288         };
1289         //static const uint8_t signature_algorithms[] = {
1290         //      000d
1291         //      0020
1292         //      001e
1293         //      0601 0602 0603 0501 0502 0503 0401 0402 0403 0301 0302 0303 0201 0202 0203
1294         //};
1295
1296         struct client_hello {
1297                 uint8_t type;
1298                 uint8_t len24_hi, len24_mid, len24_lo;
1299                 uint8_t proto_maj, proto_min;
1300                 uint8_t rand32[32];
1301                 uint8_t session_id_len;
1302                 /* uint8_t session_id[]; */
1303                 uint8_t cipherid_len16_hi, cipherid_len16_lo;
1304                 uint8_t cipherid[2 * (2 + !!CIPHER_ID2 + !!CIPHER_ID3)]; /* actually variable */
1305                 uint8_t comprtypes_len;
1306                 uint8_t comprtypes[1]; /* actually variable */
1307                 /* Extensions (SNI shown):
1308                  * hi,lo // len of all extensions
1309                  *   00,00 // extension_type: "Server Name"
1310                  *   00,0e // list len (there can be more than one SNI)
1311                  *     00,0c // len of 1st Server Name Indication
1312                  *       00    // name type: host_name
1313                  *       00,09   // name len
1314                  *       "localhost" // name
1315                  */
1316 // GNU Wget 1.18 to cdn.kernel.org sends these extensions:
1317 // 0055
1318 //   0005 0005 0100000000 - status_request
1319 //   0000 0013 0011 00 000e 63646e 2e 6b65726e656c 2e 6f7267 - server_name
1320 //   ff01 0001 00 - renegotiation_info
1321 //   0023 0000 - session_ticket
1322 //   000a 0008 0006001700180019 - supported_groups
1323 //   000b 0002 0100 - ec_point_formats
1324 //   000d 0016 0014 0401 0403 0501 0503 0601 0603 0301 0303 0201 0203 - signature_algorithms
1325 // wolfssl library sends this option, RFC 7627 (closes a security weakness, some servers may require it. TODO?):
1326 //   0017 0000 - extended master secret
1327         };
1328         struct client_hello *record;
1329         uint8_t *ptr;
1330         int len;
1331         int ext_len;
1332         int sni_len = sni ? strnlen(sni, 127 - 5) : 0;
1333
1334         ext_len = 0;
1335         /* is.gd responds with "handshake failure" to our hello if there's no supported_groups element */
1336         ext_len += sizeof(supported_groups);
1337         if (sni_len)
1338                 ext_len += 9 + sni_len;
1339
1340         /* +2 is for "len of all extensions" 2-byte field */
1341         len = sizeof(*record) + 2 + ext_len;
1342         record = tls_get_zeroed_outbuf(tls, len);
1343
1344         fill_handshake_record_hdr(record, HANDSHAKE_CLIENT_HELLO, len);
1345         record->proto_maj = TLS_MAJ;    /* the "requested" version of the protocol, */
1346         record->proto_min = TLS_MIN;    /* can be higher than one in record headers */
1347         tls_get_random(record->rand32, sizeof(record->rand32));
1348         if (TLS_DEBUG_FIXED_SECRETS)
1349                 memset(record->rand32, 0x11, sizeof(record->rand32));
1350         /* record->session_id_len = 0; - already is */
1351
1352         /* record->cipherid_len16_hi = 0; */
1353         record->cipherid_len16_lo = sizeof(record->cipherid);
1354         /* RFC 5746 Renegotiation Indication Extension - some servers will refuse to work with us otherwise */
1355         /*record->cipherid[0] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV >> 8; - zero */
1356         record->cipherid[1] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV & 0xff;
1357         if ((CIPHER_ID1 >> 8) != 0) record->cipherid[2] = CIPHER_ID1 >> 8;
1358         /*************************/ record->cipherid[3] = CIPHER_ID1 & 0xff;
1359 #if CIPHER_ID2
1360         if ((CIPHER_ID2 >> 8) != 0) record->cipherid[4] = CIPHER_ID2 >> 8;
1361         /*************************/ record->cipherid[5] = CIPHER_ID2 & 0xff;
1362 #endif
1363 #if CIPHER_ID3
1364         if ((CIPHER_ID3 >> 8) != 0) record->cipherid[6] = CIPHER_ID3 >> 8;
1365         /*************************/ record->cipherid[7] = CIPHER_ID3 & 0xff;
1366 #endif
1367
1368         record->comprtypes_len = 1;
1369         /* record->comprtypes[0] = 0; */
1370
1371         ptr = (void*)(record + 1);
1372         *ptr++ = ext_len >> 8;
1373         *ptr++ = ext_len;
1374         if (sni_len) {
1375                 //ptr[0] = 0;             //
1376                 //ptr[1] = 0;             //extension_type
1377                 //ptr[2] = 0;         //
1378                 ptr[3] = sni_len + 5; //list len
1379                 //ptr[4] = 0;             //
1380                 ptr[5] = sni_len + 3;     //len of 1st SNI
1381                 //ptr[6] = 0;         //name type
1382                 //ptr[7] = 0;             //
1383                 ptr[8] = sni_len;         //name len
1384                 ptr = mempcpy(&ptr[9], sni, sni_len);
1385         }
1386         memcpy(ptr, supported_groups, sizeof(supported_groups));
1387
1388         dbg(">> CLIENT_HELLO\n");
1389         /* Can hash it only when we know which MAC hash to use */
1390         /*xwrite_and_update_handshake_hash(tls, len); - WRONG! */
1391         xwrite_handshake_record(tls, len);
1392
1393         tls->hsd = xzalloc(sizeof(*tls->hsd) + len);
1394         tls->hsd->saved_client_hello_size = len;
1395         memcpy(tls->hsd->saved_client_hello, record, len);
1396         memcpy(tls->hsd->client_and_server_rand32, record->rand32, sizeof(record->rand32));
1397 }
1398
1399 static void get_server_hello(tls_state_t *tls)
1400 {
1401         struct server_hello {
1402                 struct record_hdr xhdr;
1403                 uint8_t type;
1404                 uint8_t len24_hi, len24_mid, len24_lo;
1405                 uint8_t proto_maj, proto_min;
1406                 uint8_t rand32[32]; /* first 4 bytes are unix time in BE format */
1407                 uint8_t session_id_len;
1408                 uint8_t session_id[32];
1409                 uint8_t cipherid_hi, cipherid_lo;
1410                 uint8_t comprtype;
1411                 /* extensions may follow, but only those which client offered in its Hello */
1412         };
1413
1414         struct server_hello *hp;
1415         uint8_t *cipherid;
1416         unsigned cipher;
1417         int len, len24;
1418
1419         len = tls_xread_handshake_block(tls, 74 - 32);
1420
1421         hp = (void*)tls->inbuf;
1422         // 74 bytes:
1423         // 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|
1424         //SvHl len=70 maj.min unixtime^^^ 28randbytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^ slen sid32bytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cipSel comprSel
1425         if (hp->type != HANDSHAKE_SERVER_HELLO
1426          || hp->len24_hi  != 0
1427          || hp->len24_mid != 0
1428          /* hp->len24_lo checked later */
1429          || hp->proto_maj != TLS_MAJ
1430          || hp->proto_min != TLS_MIN
1431         ) {
1432                 bad_record_die(tls, "'server hello'", len);
1433         }
1434
1435         cipherid = &hp->cipherid_hi;
1436         len24 = hp->len24_lo;
1437         if (hp->session_id_len != 32) {
1438                 if (hp->session_id_len != 0)
1439                         bad_record_die(tls, "'server hello'", len);
1440
1441                 // session_id_len == 0: no session id
1442                 // "The server
1443                 // may return an empty session_id to indicate that the session will
1444                 // not be cached and therefore cannot be resumed."
1445                 cipherid -= 32;
1446                 len24 += 32; /* what len would be if session id would be present */
1447         }
1448
1449         if (len24 < 70
1450 //       || cipherid[0]  != (CIPHER_ID >> 8)
1451 //       || cipherid[1]  != (CIPHER_ID & 0xff)
1452 //       || cipherid[2]  != 0 /* comprtype */
1453         ) {
1454                 bad_record_die(tls, "'server hello'", len);
1455         }
1456         dbg("<< SERVER_HELLO\n");
1457
1458         memcpy(tls->hsd->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32));
1459
1460         tls->cipher_id = cipher = 0x100 * cipherid[0] + cipherid[1];
1461         dbg("server chose cipher %04x\n", cipher);
1462
1463         if (cipher == TLS_RSA_WITH_AES_128_CBC_SHA
1464          || cipher == TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
1465         ) {
1466                 tls->key_size = AES128_KEYSIZE;
1467                 tls->MAC_size = SHA1_OUTSIZE;
1468         }
1469         else { /* TLS_RSA_WITH_AES_256_CBC_SHA256 */
1470                 tls->key_size = AES256_KEYSIZE;
1471                 tls->MAC_size = SHA256_OUTSIZE;
1472         }
1473         /* Handshake hash eventually destined to FINISHED record
1474          * is sha256 regardless of cipher
1475          * (at least for all ciphers defined by RFC5246).
1476          * It's not sha1 for AES_128_CBC_SHA - only MAC is sha1, not this hash.
1477          */
1478         sha256_begin(&tls->hsd->handshake_hash_ctx);
1479         hash_handshake(tls, ">> client hello hash:%s",
1480                 tls->hsd->saved_client_hello, tls->hsd->saved_client_hello_size
1481         );
1482         hash_handshake(tls, "<< server hello hash:%s",
1483                 tls->inbuf + RECHDR_LEN, len
1484         );
1485 }
1486
1487 static void get_server_cert(tls_state_t *tls)
1488 {
1489         struct record_hdr *xhdr;
1490         uint8_t *certbuf;
1491         int len, len1;
1492
1493         len = tls_xread_handshake_block(tls, 10);
1494
1495         xhdr = (void*)tls->inbuf;
1496         certbuf = (void*)(xhdr + 1);
1497         if (certbuf[0] != HANDSHAKE_CERTIFICATE)
1498                 bad_record_die(tls, "certificate", len);
1499         dbg("<< CERTIFICATE\n");
1500         // 4392 bytes:
1501         // 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...
1502         //Cert len=4388 ChainLen CertLen^ DER encoded X509 starts here. openssl x509 -in FILE -inform DER -noout -text
1503         len1 = get24be(certbuf + 1);
1504         if (len1 > len - 4) tls_error_die(tls);
1505         len = len1;
1506         len1 = get24be(certbuf + 4);
1507         if (len1 > len - 3) tls_error_die(tls);
1508         len = len1;
1509         len1 = get24be(certbuf + 7);
1510         if (len1 > len - 3) tls_error_die(tls);
1511         len = len1;
1512
1513         if (len)
1514                 find_key_in_der_cert(tls, certbuf + 10, len);
1515 }
1516
1517 /* On input, len is known to be >= 4.
1518  * The record is known to be SERVER_KEY_EXCHANGE.
1519  */
1520 static void process_server_key(tls_state_t *tls, int len)
1521 {
1522         struct record_hdr *xhdr;
1523         uint8_t *keybuf;
1524         int len1;
1525         uint32_t t32;
1526
1527         xhdr = (void*)tls->inbuf;
1528         keybuf = (void*)(xhdr + 1);
1529 //seen from is.gd: it selects curve_x25519:
1530 //  0c 00006e //SERVER_KEY_EXCHANGE
1531 //    03 //curve_type: named curve
1532 //    001d //curve_x25519
1533 //server-chosen EC point, and then signed_params
1534 //      (rfc8422: "A hash of the params, with the signature
1535 //      appropriate to that hash applied.  The private key corresponding
1536 //      to the certified public key in the server's Certificate message is
1537 //      used for signing.")
1538 //follow. Format unclear/guessed:
1539 //    20 //eccPubKeyLen
1540 //      25511923d73b70dd2f60e66ba2f3fda31a9c25170963c7a3a972e481dbb2835d //eccPubKey (32bytes)
1541 //    0203 //hashSigAlg: 2:SHA1 (4:SHA256 5:SHA384 6:SHA512), 3:ECDSA (1:RSA)
1542 //    0046 //len (16bit)
1543 //      30 44 //SEQ, len
1544 //        02 20 //INTEGER, len
1545 //          2e18e7c2a9badd0a70cd3059a6ab114539b9f5163568911147386cd77ed7c412 //32bytes
1546 //this item ^^^^^ is sometimes 33 bytes (with all container sizes also +1)
1547 //        02 20 //INTEGER, len
1548 //          64523d6216cb94c43c9b20e377d8c52c55be6703fd6730a155930c705eaf3af6 //32bytes
1549 //same about this item ^^^^^
1550         /* Get and verify length */
1551         len1 = get24be(keybuf + 1);
1552         if (len1 > len - 4) tls_error_die(tls);
1553         len = len1;
1554         if (len < (1+2+1+32)) tls_error_die(tls);
1555         keybuf += 4;
1556
1557         /* So far we only support curve_x25519 */
1558         move_from_unaligned32(t32, keybuf);
1559         if (t32 != htonl(0x03001d20))
1560                 bb_error_msg_and_die("elliptic curve is not x25519");
1561
1562         memcpy(tls->hsd->ecc_pub_key32, keybuf + 4, 32);
1563         dbg("got eccPubKey\n");
1564 }
1565
1566 static void send_empty_client_cert(tls_state_t *tls)
1567 {
1568         struct client_empty_cert {
1569                 uint8_t type;
1570                 uint8_t len24_hi, len24_mid, len24_lo;
1571                 uint8_t cert_chain_len24_hi, cert_chain_len24_mid, cert_chain_len24_lo;
1572         };
1573         struct client_empty_cert *record;
1574
1575         record = tls_get_zeroed_outbuf(tls, sizeof(*record));
1576         //fill_handshake_record_hdr(record, HANDSHAKE_CERTIFICATE, sizeof(*record));
1577         //record->cert_chain_len24_hi = 0;
1578         //record->cert_chain_len24_mid = 0;
1579         //record->cert_chain_len24_lo = 0;
1580         // same as above:
1581         record->type = HANDSHAKE_CERTIFICATE;
1582         record->len24_lo = 3;
1583
1584         dbg(">> CERTIFICATE\n");
1585         xwrite_and_update_handshake_hash(tls, sizeof(*record));
1586 }
1587
1588 static void send_client_key_exchange(tls_state_t *tls)
1589 {
1590         struct client_key_exchange {
1591                 uint8_t type;
1592                 uint8_t len24_hi, len24_mid, len24_lo;
1593                 uint8_t key[2 + 4 * 1024]; // size??
1594         };
1595 //FIXME: better size estimate
1596         struct client_key_exchange *record = tls_get_zeroed_outbuf(tls, sizeof(*record));
1597         uint8_t rsa_premaster[RSA_PREMASTER_SIZE];
1598         uint8_t x25519_premaster[CURVE25519_KEYSIZE];
1599         uint8_t *premaster;
1600         int premaster_size;
1601         int len;
1602
1603         if (tls->hsd->key_alg == KEY_ALG_RSA) {
1604                 tls_get_random(rsa_premaster, sizeof(rsa_premaster));
1605                 if (TLS_DEBUG_FIXED_SECRETS)
1606                         memset(rsa_premaster, 0x44, sizeof(rsa_premaster));
1607                 // RFC 5246
1608                 // "Note: The version number in the PreMasterSecret is the version
1609                 // offered by the client in the ClientHello.client_version, not the
1610                 // version negotiated for the connection."
1611                 rsa_premaster[0] = TLS_MAJ;
1612                 rsa_premaster[1] = TLS_MIN;
1613                 dump_hex("premaster:%s\n", rsa_premaster, sizeof(rsa_premaster));
1614                 len = psRsaEncryptPub(/*pool:*/ NULL,
1615                         /* psRsaKey_t* */ &tls->hsd->server_rsa_pub_key,
1616                         rsa_premaster, /*inlen:*/ sizeof(rsa_premaster),
1617                         record->key + 2, sizeof(record->key) - 2,
1618                         data_param_ignored
1619                 );
1620                 /* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */
1621                 record->key[0] = len >> 8;
1622                 record->key[1] = len & 0xff;
1623                 len += 2;
1624                 premaster = rsa_premaster;
1625                 premaster_size = sizeof(rsa_premaster);
1626         } else {
1627                 /* KEY_ALG_ECDSA */
1628                 static const uint8_t basepoint9[CURVE25519_KEYSIZE] = {9};
1629                 uint8_t privkey[CURVE25519_KEYSIZE]; //[32]
1630
1631                 /* Generate random private key, see RFC 7748 */
1632                 tls_get_random(privkey, sizeof(privkey));
1633                 privkey[0] &= 0xf8;
1634                 privkey[CURVE25519_KEYSIZE-1] = ((privkey[CURVE25519_KEYSIZE-1] & 0x7f) | 0x40);
1635
1636                 /* Compute public key */
1637                 curve25519(record->key + 1, privkey, basepoint9);
1638
1639                 /* Compute premaster using peer's public key */
1640                 dbg("computing x25519_premaster\n");
1641                 curve25519(x25519_premaster, privkey, tls->hsd->ecc_pub_key32);
1642
1643                 len = CURVE25519_KEYSIZE;
1644                 record->key[0] = len;
1645                 len++;
1646                 premaster = x25519_premaster;
1647                 premaster_size = sizeof(x25519_premaster);
1648         }
1649
1650         record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
1651         /* record->len24_hi = 0; - already is */
1652         record->len24_mid = len >> 8;
1653         record->len24_lo  = len & 0xff;
1654         len += 4;
1655
1656         dbg(">> CLIENT_KEY_EXCHANGE\n");
1657         xwrite_and_update_handshake_hash(tls, len);
1658
1659         // RFC 5246
1660         // For all key exchange methods, the same algorithm is used to convert
1661         // the pre_master_secret into the master_secret.  The pre_master_secret
1662         // should be deleted from memory once the master_secret has been
1663         // computed.
1664         //      master_secret = PRF(pre_master_secret, "master secret",
1665         //                          ClientHello.random + ServerHello.random)
1666         //                          [0..47];
1667         // The master secret is always exactly 48 bytes in length.  The length
1668         // of the premaster secret will vary depending on key exchange method.
1669         prf_hmac_sha256(/*tls,*/
1670                 tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1671                 premaster, premaster_size,
1672                 "master secret",
1673                 tls->hsd->client_and_server_rand32, sizeof(tls->hsd->client_and_server_rand32)
1674         );
1675         dump_hex("master secret:%s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
1676
1677         // RFC 5246
1678         // 6.3.  Key Calculation
1679         //
1680         // The Record Protocol requires an algorithm to generate keys required
1681         // by the current connection state (see Appendix A.6) from the security
1682         // parameters provided by the handshake protocol.
1683         //
1684         // The master secret is expanded into a sequence of secure bytes, which
1685         // is then split to a client write MAC key, a server write MAC key, a
1686         // client write encryption key, and a server write encryption key.  Each
1687         // of these is generated from the byte sequence in that order.  Unused
1688         // values are empty.  Some AEAD ciphers may additionally require a
1689         // client write IV and a server write IV (see Section 6.2.3.3).
1690         //
1691         // When keys and MAC keys are generated, the master secret is used as an
1692         // entropy source.
1693         //
1694         // To generate the key material, compute
1695         //
1696         //    key_block = PRF(SecurityParameters.master_secret,
1697         //                    "key expansion",
1698         //                    SecurityParameters.server_random +
1699         //                    SecurityParameters.client_random);
1700         //
1701         // until enough output has been generated.  Then, the key_block is
1702         // partitioned as follows:
1703         //
1704         //    client_write_MAC_key[SecurityParameters.mac_key_length]
1705         //    server_write_MAC_key[SecurityParameters.mac_key_length]
1706         //    client_write_key[SecurityParameters.enc_key_length]
1707         //    server_write_key[SecurityParameters.enc_key_length]
1708         //    client_write_IV[SecurityParameters.fixed_iv_length]
1709         //    server_write_IV[SecurityParameters.fixed_iv_length]
1710         {
1711                 uint8_t tmp64[64];
1712
1713                 /* make "server_rand32 + client_rand32" */
1714                 memcpy(&tmp64[0] , &tls->hsd->client_and_server_rand32[32], 32);
1715                 memcpy(&tmp64[32], &tls->hsd->client_and_server_rand32[0] , 32);
1716
1717                 prf_hmac_sha256(/*tls,*/
1718                         tls->client_write_MAC_key, 2 * (tls->MAC_size + tls->key_size),
1719                         // also fills:
1720                         // server_write_MAC_key[]
1721                         // client_write_key[]
1722                         // server_write_key[]
1723                         tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1724                         "key expansion",
1725                         tmp64, 64
1726                 );
1727                 tls->client_write_key = tls->client_write_MAC_key + (2 * tls->MAC_size);
1728                 tls->server_write_key = tls->client_write_key + tls->key_size;
1729                 dump_hex("client_write_MAC_key:%s\n",
1730                         tls->client_write_MAC_key, tls->MAC_size
1731                 );
1732                 dump_hex("client_write_key:%s\n",
1733                         tls->client_write_key, tls->key_size
1734                 );
1735         }
1736 }
1737
1738 static const uint8_t rec_CHANGE_CIPHER_SPEC[] = {
1739         RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01,
1740         01
1741 };
1742
1743 static void send_change_cipher_spec(tls_state_t *tls)
1744 {
1745         dbg(">> CHANGE_CIPHER_SPEC\n");
1746         xwrite(tls->ofd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC));
1747 }
1748
1749 // 7.4.9.  Finished
1750 // A Finished message is always sent immediately after a change
1751 // cipher spec message to verify that the key exchange and
1752 // authentication processes were successful.  It is essential that a
1753 // change cipher spec message be received between the other handshake
1754 // messages and the Finished message.
1755 //...
1756 // The Finished message is the first one protected with the just
1757 // negotiated algorithms, keys, and secrets.  Recipients of Finished
1758 // messages MUST verify that the contents are correct.  Once a side
1759 // has sent its Finished message and received and validated the
1760 // Finished message from its peer, it may begin to send and receive
1761 // application data over the connection.
1762 //...
1763 // struct {
1764 //     opaque verify_data[verify_data_length];
1765 // } Finished;
1766 //
1767 // verify_data
1768 //    PRF(master_secret, finished_label, Hash(handshake_messages))
1769 //       [0..verify_data_length-1];
1770 //
1771 // finished_label
1772 //    For Finished messages sent by the client, the string
1773 //    "client finished".  For Finished messages sent by the server,
1774 //    the string "server finished".
1775 //
1776 // Hash denotes a Hash of the handshake messages.  For the PRF
1777 // defined in Section 5, the Hash MUST be the Hash used as the basis
1778 // for the PRF.  Any cipher suite which defines a different PRF MUST
1779 // also define the Hash to use in the Finished computation.
1780 //
1781 // In previous versions of TLS, the verify_data was always 12 octets
1782 // long.  In the current version of TLS, it depends on the cipher
1783 // suite.  Any cipher suite which does not explicitly specify
1784 // verify_data_length has a verify_data_length equal to 12.  This
1785 // includes all existing cipher suites.
1786 static void send_client_finished(tls_state_t *tls)
1787 {
1788         struct finished {
1789                 uint8_t type;
1790                 uint8_t len24_hi, len24_mid, len24_lo;
1791                 uint8_t prf_result[12];
1792         };
1793         struct finished *record = tls_get_outbuf(tls, sizeof(*record));
1794         uint8_t handshake_hash[TLS_MAX_MAC_SIZE];
1795         unsigned len;
1796
1797         fill_handshake_record_hdr(record, HANDSHAKE_FINISHED, sizeof(*record));
1798
1799         len = get_handshake_hash(tls, handshake_hash);
1800         prf_hmac_sha256(/*tls,*/
1801                 record->prf_result, sizeof(record->prf_result),
1802                 tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1803                 "client finished",
1804                 handshake_hash, len
1805         );
1806         dump_hex("from secret: %s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
1807         dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1);
1808         dump_hex("%s\n", handshake_hash, sizeof(handshake_hash));
1809         dump_hex("=> digest: %s\n", record->prf_result, sizeof(record->prf_result));
1810
1811         dbg(">> FINISHED\n");
1812         xwrite_encrypted(tls, sizeof(*record), RECORD_TYPE_HANDSHAKE);
1813 }
1814
1815 void FAST_FUNC tls_handshake(tls_state_t *tls, const char *sni)
1816 {
1817         // Client              RFC 5246                Server
1818         // (*) - optional messages, not always sent
1819         //
1820         // ClientHello          ------->
1821         //                                        ServerHello
1822         //                                       Certificate*
1823         //                                 ServerKeyExchange*
1824         //                                CertificateRequest*
1825         //                      <-------      ServerHelloDone
1826         // Certificate*
1827         // ClientKeyExchange
1828         // CertificateVerify*
1829         // [ChangeCipherSpec]
1830         // Finished             ------->
1831         //                                 [ChangeCipherSpec]
1832         //                      <-------             Finished
1833         // Application Data     <------>     Application Data
1834         int len;
1835         int got_cert_req;
1836
1837         send_client_hello_and_alloc_hsd(tls, sni);
1838         get_server_hello(tls);
1839
1840         // RFC 5246
1841         // The server MUST send a Certificate message whenever the agreed-
1842         // upon key exchange method uses certificates for authentication
1843         // (this includes all key exchange methods defined in this document
1844         // except DH_anon).  This message will always immediately follow the
1845         // ServerHello message.
1846         //
1847         // IOW: in practice, Certificate *always* follows.
1848         // (for example, kernel.org does not even accept DH_anon cipher id)
1849         get_server_cert(tls);
1850
1851         len = tls_xread_handshake_block(tls, 4);
1852         if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_SERVER_KEY_EXCHANGE) {
1853                 // 459 bytes:
1854                 // 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...
1855                 //SvKey len=455^
1856                 // with TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: 461 bytes:
1857                 // 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...
1858                 //
1859                 // RFC 8422 5.4. Server Key Exchange
1860                 // This message is sent when using the ECDHE_ECDSA, ECDHE_RSA, and
1861                 // ECDH_anon key exchange algorithms.
1862                 // This message is used to convey the server's ephemeral ECDH public key
1863                 // (and the corresponding elliptic curve domain parameters) to the
1864                 // client.
1865                 dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len);
1866                 dump_raw_in("<< %s\n", tls->inbuf, RECHDR_LEN + len);
1867                 if (tls->hsd->key_alg == KEY_ALG_ECDSA)
1868                         process_server_key(tls, len);
1869
1870                 // read next handshake block
1871                 len = tls_xread_handshake_block(tls, 4);
1872         }
1873
1874         got_cert_req = (tls->inbuf[RECHDR_LEN] == HANDSHAKE_CERTIFICATE_REQUEST);
1875         if (got_cert_req) {
1876                 dbg("<< CERTIFICATE_REQUEST\n");
1877                 // RFC 5246: "If no suitable certificate is available,
1878                 // the client MUST send a certificate message containing no
1879                 // certificates.  That is, the certificate_list structure has a
1880                 // length of zero. ...
1881                 // Client certificates are sent using the Certificate structure
1882                 // defined in Section 7.4.2."
1883                 // (i.e. the same format as server certs)
1884
1885                 /*send_empty_client_cert(tls); - WRONG (breaks handshake hash calc) */
1886                 /* need to hash _all_ server replies first, up to ServerHelloDone */
1887                 len = tls_xread_handshake_block(tls, 4);
1888         }
1889
1890         if (tls->inbuf[RECHDR_LEN] != HANDSHAKE_SERVER_HELLO_DONE) {
1891                 bad_record_die(tls, "'server hello done'", len);
1892         }
1893         // 0e 000000 (len:0)
1894         dbg("<< SERVER_HELLO_DONE\n");
1895
1896         if (got_cert_req)
1897                 send_empty_client_cert(tls);
1898
1899         send_client_key_exchange(tls);
1900
1901         send_change_cipher_spec(tls);
1902         /* from now on we should send encrypted */
1903         /* tls->write_seq64_be = 0; - already is */
1904         tls->encrypt_on_write = 1;
1905
1906         send_client_finished(tls);
1907
1908         /* Get CHANGE_CIPHER_SPEC */
1909         len = tls_xread_record(tls, "switch to encrypted traffic");
1910         if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0)
1911                 bad_record_die(tls, "switch to encrypted traffic", len);
1912         dbg("<< CHANGE_CIPHER_SPEC\n");
1913         if (CIPHER_ID1 == TLS_RSA_WITH_NULL_SHA256
1914          && tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
1915         ) {
1916                 tls->min_encrypted_len_on_read = tls->MAC_size;
1917         } else {
1918                 unsigned mac_blocks = (unsigned)(tls->MAC_size + AES_BLOCKSIZE-1) / AES_BLOCKSIZE;
1919                 /* all incoming packets now should be encrypted and have
1920                  * at least IV + (MAC padded to blocksize):
1921                  */
1922                 tls->min_encrypted_len_on_read = AES_BLOCKSIZE + (mac_blocks * AES_BLOCKSIZE);
1923                 dbg("min_encrypted_len_on_read: %u", tls->min_encrypted_len_on_read);
1924         }
1925
1926         /* Get (encrypted) FINISHED from the server */
1927         len = tls_xread_record(tls, "'server finished'");
1928         if (len < 4 || tls->inbuf[RECHDR_LEN] != HANDSHAKE_FINISHED)
1929                 bad_record_die(tls, "'server finished'", len);
1930         dbg("<< FINISHED\n");
1931         /* application data can be sent/received */
1932
1933         /* free handshake data */
1934 //      if (PARANOIA)
1935 //              memset(tls->hsd, 0, tls->hsd->hsd_size);
1936         free(tls->hsd);
1937         tls->hsd = NULL;
1938 }
1939
1940 static void tls_xwrite(tls_state_t *tls, int len)
1941 {
1942         dbg(">> DATA\n");
1943         xwrite_encrypted(tls, len, RECORD_TYPE_APPLICATION_DATA);
1944 }
1945
1946 // To run a test server using openssl:
1947 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
1948 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1
1949 //
1950 // Unencryped SHA256 example:
1951 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
1952 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL
1953 // openssl s_client -connect 127.0.0.1:4433 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL-SHA256
1954
1955 void FAST_FUNC tls_run_copy_loop(tls_state_t *tls, unsigned flags)
1956 {
1957         int inbuf_size;
1958         const int INBUF_STEP = 4 * 1024;
1959         struct pollfd pfds[2];
1960
1961         pfds[0].fd = STDIN_FILENO;
1962         pfds[0].events = POLLIN;
1963         pfds[1].fd = tls->ifd;
1964         pfds[1].events = POLLIN;
1965
1966         inbuf_size = INBUF_STEP;
1967         for (;;) {
1968                 int nread;
1969
1970                 if (safe_poll(pfds, 2, -1) < 0)
1971                         bb_perror_msg_and_die("poll");
1972
1973                 if (pfds[0].revents) {
1974                         void *buf;
1975
1976                         dbg("STDIN HAS DATA\n");
1977                         buf = tls_get_outbuf(tls, inbuf_size);
1978                         nread = safe_read(STDIN_FILENO, buf, inbuf_size);
1979                         if (nread < 1) {
1980                                 /* We'd want to do this: */
1981                                 /* Close outgoing half-connection so they get EOF,
1982                                  * but leave incoming alone so we can see response
1983                                  */
1984                                 //shutdown(tls->ofd, SHUT_WR);
1985                                 /* But TLS has no way to encode this,
1986                                  * doubt it's ok to do it "raw"
1987                                  */
1988                                 pfds[0].fd = -1;
1989                                 tls_free_outbuf(tls); /* mem usage optimization */
1990                                 if (flags & TLSLOOP_EXIT_ON_LOCAL_EOF)
1991                                         break;
1992                         } else {
1993                                 if (nread == inbuf_size) {
1994                                         /* TLS has per record overhead, if input comes fast,
1995                                          * read, encrypt and send bigger chunks
1996                                          */
1997                                         inbuf_size += INBUF_STEP;
1998                                         if (inbuf_size > TLS_MAX_OUTBUF)
1999                                                 inbuf_size = TLS_MAX_OUTBUF;
2000                                 }
2001                                 tls_xwrite(tls, nread);
2002                         }
2003                 }
2004                 if (pfds[1].revents) {
2005                         dbg("NETWORK HAS DATA\n");
2006  read_record:
2007                         nread = tls_xread_record(tls, "encrypted data");
2008                         if (nread < 1) {
2009                                 /* TLS protocol has no real concept of one-sided shutdowns:
2010                                  * if we get "TLS EOF" from the peer, writes will fail too
2011                                  */
2012                                 //pfds[1].fd = -1;
2013                                 //close(STDOUT_FILENO);
2014                                 //tls_free_inbuf(tls); /* mem usage optimization */
2015                                 //continue;
2016                                 break;
2017                         }
2018                         if (tls->inbuf[0] != RECORD_TYPE_APPLICATION_DATA)
2019                                 bad_record_die(tls, "encrypted data", nread);
2020                         xwrite(STDOUT_FILENO, tls->inbuf + RECHDR_LEN, nread);
2021                         /* We may already have a complete next record buffered,
2022                          * can process it without network reads (and possible blocking)
2023                          */
2024                         if (tls_has_buffered_record(tls))
2025                                 goto read_record;
2026                 }
2027         }
2028 }