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_rsa.o
  16 //kbuild:lib-$(CONFIG_TLS) += tls_aes.o
  17 ////kbuild:lib-$(CONFIG_TLS) += tls_aes_gcm.o
  18
  19 #include "tls.h"
  20
  21 //Tested against kernel.org:
  22 //TLS 1.2
  23 #define TLS_MAJ 3
  24 #define TLS_MIN 3
  25 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE *** matrixssl uses this on my box
  26 //#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE
  27 //#define CIPHER_ID TLS_DH_anon_WITH_AES_256_CBC_SHA // SSL_ALERT_HANDSHAKE_FAILURE
  28 //^^^^^^^^^^^^^^^^^^^^^^^ (tested b/c this one doesn't req server certs... no luck, server refuses it)
  29 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 // SSL_ALERT_HANDSHAKE_FAILURE
  30 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  31 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 // ok, recvs SERVER_KEY_EXCHANGE
  32 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
  33 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384
  34 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  35 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
  36 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
  37 //#define CIPHER_ID TLS_RSA_WITH_AES_256_GCM_SHA384 // ok, no SERVER_KEY_EXCHANGE
  38 //#define CIPHER_ID TLS_RSA_WITH_AES_128_GCM_SHA256 // ok, no SERVER_KEY_EXCHANGE *** select this?
  39
  40 // works against "openssl s_server -cipher NULL"
  41 // and against wolfssl-3.9.10-stable/examples/server/server.c:
  42 //#define CIPHER_ID1 TLS_RSA_WITH_NULL_SHA256 // for testing (does everything except encrypting)
  43
  44 // works against wolfssl-3.9.10-stable/examples/server/server.c
  45 // works for kernel.org
  46 // does not work for cdn.kernel.org (e.g. downloading an actual tarball, not a web page)
  47 //  getting alert 40 "handshake failure" at once
  48 //  with GNU Wget 1.18, they agree on TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xC02F) cipher
  49 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-SHA256
  50 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-GCM-SHA384
  51 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA256
  52 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-GCM-SHA256
  53 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA
  54 //        (TLS_RSA_WITH_AES_128_CBC_SHA - in TLS 1.2 it's mandated to be always supported)
  55 #define CIPHER_ID1  TLS_RSA_WITH_AES_256_CBC_SHA256 // no SERVER_KEY_EXCHANGE from peer
  56 // Works with "wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.9.5.tar.xz"
  57 #define CIPHER_ID2  TLS_RSA_WITH_AES_128_CBC_SHA
  58
  59
  60 #define TLS_DEBUG      0
  61 #define TLS_DEBUG_HASH 0
  62 #define TLS_DEBUG_DER  0
  63 #define TLS_DEBUG_FIXED_SECRETS 0
  64 #if 0
  65 # define dump_raw_out(...) dump_hex(__VA_ARGS__)
  66 #else
  67 # define dump_raw_out(...) ((void)0)
  68 #endif
  69 #if 0
  70 # define dump_raw_in(...) dump_hex(__VA_ARGS__)
  71 #else
  72 # define dump_raw_in(...) ((void)0)
  73 #endif
  74
  75 #if TLS_DEBUG
  76 # define dbg(...) fprintf(stderr, __VA_ARGS__)
  77 #else
  78 # define dbg(...) ((void)0)
  79 #endif
  80
  81 #if TLS_DEBUG_DER
  82 # define dbg_der(...) fprintf(stderr, __VA_ARGS__)
  83 #else
  84 # define dbg_der(...) ((void)0)
  85 #endif
  86
  87 #define RECORD_TYPE_CHANGE_CIPHER_SPEC  20 /* 0x14 */
  88 #define RECORD_TYPE_ALERT               21 /* 0x15 */
  89 #define RECORD_TYPE_HANDSHAKE           22 /* 0x16 */
  90 #define RECORD_TYPE_APPLICATION_DATA    23 /* 0x17 */
  91
  92 #define HANDSHAKE_HELLO_REQUEST         0  /* 0x00 */
  93 #define HANDSHAKE_CLIENT_HELLO          1  /* 0x01 */
  94 #define HANDSHAKE_SERVER_HELLO          2  /* 0x02 */
  95 #define HANDSHAKE_HELLO_VERIFY_REQUEST  3  /* 0x03 */
  96 #define HANDSHAKE_NEW_SESSION_TICKET    4  /* 0x04 */
  97 #define HANDSHAKE_CERTIFICATE           11 /* 0x0b */
  98 #define HANDSHAKE_SERVER_KEY_EXCHANGE   12 /* 0x0c */
  99 #define HANDSHAKE_CERTIFICATE_REQUEST   13 /* 0x0d */
 100 #define HANDSHAKE_SERVER_HELLO_DONE     14 /* 0x0e */
 101 #define HANDSHAKE_CERTIFICATE_VERIFY    15 /* 0x0f */
 102 #define HANDSHAKE_CLIENT_KEY_EXCHANGE   16 /* 0x10 */
 103 #define HANDSHAKE_FINISHED              20 /* 0x14 */
 104
 105 #define SSL_NULL_WITH_NULL_NULL                 0x0000
 106 #define SSL_RSA_WITH_NULL_MD5                   0x0001
 107 #define SSL_RSA_WITH_NULL_SHA                   0x0002
 108 #define SSL_RSA_WITH_RC4_128_MD5                0x0004
 109 #define SSL_RSA_WITH_RC4_128_SHA                0x0005
 110 #define SSL_RSA_WITH_3DES_EDE_CBC_SHA           0x000A  /* 10 */
 111 #define TLS_RSA_WITH_AES_128_CBC_SHA            0x002F  /* 47 */
 112 #define TLS_RSA_WITH_AES_256_CBC_SHA            0x0035  /* 53 */
 113 #define TLS_RSA_WITH_NULL_SHA256                0x003B  /* 59 */
 114
 115 #define TLS_EMPTY_RENEGOTIATION_INFO_SCSV       0x00FF
 116
 117 #define TLS_RSA_WITH_IDEA_CBC_SHA               0x0007  /* 7 */
 118 #define SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA       0x0016  /* 22 */
 119 #define SSL_DH_anon_WITH_RC4_128_MD5            0x0018  /* 24 */
 120 #define SSL_DH_anon_WITH_3DES_EDE_CBC_SHA       0x001B  /* 27 */
 121 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA        0x0033  /* 51 */
 122 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA        0x0039  /* 57 */
 123 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256     0x0067  /* 103 */
 124 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256     0x006B  /* 107 */
 125 #define TLS_DH_anon_WITH_AES_128_CBC_SHA        0x0034  /* 52 */
 126 #define TLS_DH_anon_WITH_AES_256_CBC_SHA        0x003A  /* 58 */
 127 #define TLS_RSA_WITH_AES_128_CBC_SHA256         0x003C  /* 60 */
 128 #define TLS_RSA_WITH_AES_256_CBC_SHA256         0x003D  /* 61 */
 129 #define TLS_RSA_WITH_SEED_CBC_SHA               0x0096  /* 150 */
 130 #define TLS_PSK_WITH_AES_128_CBC_SHA            0x008C  /* 140 */
 131 #define TLS_PSK_WITH_AES_128_CBC_SHA256         0x00AE  /* 174 */
 132 #define TLS_PSK_WITH_AES_256_CBC_SHA384         0x00AF  /* 175 */
 133 #define TLS_PSK_WITH_AES_256_CBC_SHA            0x008D  /* 141 */
 134 #define TLS_DHE_PSK_WITH_AES_128_CBC_SHA        0x0090  /* 144 */
 135 #define TLS_DHE_PSK_WITH_AES_256_CBC_SHA        0x0091  /* 145 */
 136 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA     0xC004  /* 49156 */
 137 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA     0xC005  /* 49157 */
 138 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA    0xC009  /* 49161 */
 139 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA    0xC00A  /* 49162 */
 140 #define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA     0xC012  /* 49170 */
 141 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA      0xC013  /* 49171 */
 142 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA      0xC014  /* 49172 */
 143 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA       0xC00E  /* 49166 */
 144 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA       0xC00F  /* 49167 */
 145 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 0xC023  /* 49187 */
 146 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024  /* 49188 */
 147 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256  0xC025  /* 49189 */
 148 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384  0xC026  /* 49190 */
 149 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256   0xC027  /* 49191 */
 150 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384   0xC028  /* 49192 */
 151 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256    0xC029  /* 49193 */
 152 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384    0xC02A  /* 49194 */
 153
 154 /* RFC 5288 "AES Galois Counter Mode (GCM) Cipher Suites for TLS" */
 155 #define TLS_RSA_WITH_AES_128_GCM_SHA256         0x009C  /* 156 */
 156 #define TLS_RSA_WITH_AES_256_GCM_SHA384         0x009D  /* 157 */
 157 #define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B  /* 49195 */
 158 #define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C  /* 49196 */
 159 #define TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256  0xC02D  /* 49197 */
 160 #define TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384  0xC02E  /* 49198 */
 161 #define TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256   0xC02F  /* 49199 */
 162 #define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384   0xC030  /* 49200 */
 163 #define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256    0xC031  /* 49201 */
 164 #define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384    0xC032  /* 49202 */
 165
 166 /* Might go to libbb.h */
 167 #define TLS_MAX_CRYPTBLOCK_SIZE 16
 168 #define TLS_MAX_OUTBUF          (1 << 14)
 169
 170 enum {
 171         SHA_INSIZE     = 64,
 172         SHA1_OUTSIZE   = 20,
 173         SHA256_OUTSIZE = 32,
 174
 175         AES_BLOCKSIZE  = 16,
 176         AES128_KEYSIZE = 16,
 177         AES256_KEYSIZE = 32,
 178
 179         RSA_PREMASTER_SIZE = 48,
 180
 181         RECHDR_LEN = 5,
 182
 183         /* 8 = 3+5. 3 extra bytes result in record data being 32-bit aligned */
 184         OUTBUF_PFX = 8 + AES_BLOCKSIZE, /* header + IV */
 185         OUTBUF_SFX = TLS_MAX_MAC_SIZE + TLS_MAX_CRYPTBLOCK_SIZE, /* MAC + padding */
 186
 187         // RFC 5246
 188         // | 6.2.1. Fragmentation
 189         // |  The record layer fragments information blocks into TLSPlaintext
 190         // |  records carrying data in chunks of 2^14 bytes or less.  Client
 191         // |  message boundaries are not preserved in the record layer (i.e.,
 192         // |  multiple client messages of the same ContentType MAY be coalesced
 193         // |  into a single TLSPlaintext record, or a single message MAY be
 194         // |  fragmented across several records)
 195         // |...
 196         // |  length
 197         // |    The length (in bytes) of the following TLSPlaintext.fragment.
 198         // |    The length MUST NOT exceed 2^14.
 199         // |...
 200         // | 6.2.2. Record Compression and Decompression
 201         // |...
 202         // |  Compression must be lossless and may not increase the content length
 203         // |  by more than 1024 bytes.  If the decompression function encounters a
 204         // |  TLSCompressed.fragment that would decompress to a length in excess of
 205         // |  2^14 bytes, it MUST report a fatal decompression failure error.
 206         // |...
 207         // |  length
 208         // |    The length (in bytes) of the following TLSCompressed.fragment.
 209         // |    The length MUST NOT exceed 2^14 + 1024.
 210         // |...
 211         // | 6.2.3.  Record Payload Protection
 212         // |  The encryption and MAC functions translate a TLSCompressed
 213         // |  structure into a TLSCiphertext.  The decryption functions reverse
 214         // |  the process.  The MAC of the record also includes a sequence
 215         // |  number so that missing, extra, or repeated messages are
 216         // |  detectable.
 217         // |...
 218         // |  length
 219         // |    The length (in bytes) of the following TLSCiphertext.fragment.
 220         // |    The length MUST NOT exceed 2^14 + 2048.
 221         MAX_INBUF = RECHDR_LEN + (1 << 14) + 2048,
 222 };
 223
 224 struct record_hdr {
 225         uint8_t type;
 226         uint8_t proto_maj, proto_min;
 227         uint8_t len16_hi, len16_lo;
 228 };
 229
 230 struct tls_handshake_data {
 231         /* In bbox, md5/sha1/sha256 ctx's are the same structure */
 232         md5sha_ctx_t handshake_hash_ctx;
 233
 234         uint8_t client_and_server_rand32[2 * 32];
 235         uint8_t master_secret[48];
 236 //TODO: store just the DER key here, parse/use/delete it when sending client key
 237 //this way it will stay key type agnostic here.
 238         psRsaKey_t server_rsa_pub_key;
 239
 240         unsigned saved_client_hello_size;
 241         uint8_t saved_client_hello[1];
 242 };
 243
 244
 245 static unsigned get24be(const uint8_t *p)
 246 {
 247         return 0x100*(0x100*p[0] + p[1]) + p[2];
 248 }
 249
 250 #if TLS_DEBUG
 251 static void dump_hex(const char *fmt, const void *vp, int len)
 252 {
 253         char hexbuf[32 * 1024 + 4];
 254         const uint8_t *p = vp;
 255
 256         bin2hex(hexbuf, (void*)p, len)[0] = '\0';
 257         dbg(fmt, hexbuf);
 258 }
 259
 260 static void dump_tls_record(const void *vp, int len)
 261 {
 262         const uint8_t *p = vp;
 263
 264         while (len > 0) {
 265                 unsigned xhdr_len;
 266                 if (len < RECHDR_LEN) {
 267                         dump_hex("< |%s|\n", p, len);
 268                         return;
 269                 }
 270                 xhdr_len = 0x100*p[3] + p[4];
 271                 dbg("< hdr_type:%u ver:%u.%u len:%u", p[0], p[1], p[2], xhdr_len);
 272                 p += RECHDR_LEN;
 273                 len -= RECHDR_LEN;
 274                 if (len >= 4 && p[-RECHDR_LEN] == RECORD_TYPE_HANDSHAKE) {
 275                         unsigned len24 = get24be(p + 1);
 276                         dbg(" type:%u len24:%u", p[0], len24);
 277                 }
 278                 if (xhdr_len > len)
 279                         xhdr_len = len;
 280                 dump_hex(" |%s|\n", p, xhdr_len);
 281                 p += xhdr_len;
 282                 len -= xhdr_len;
 283         }
 284 }
 285 #else
 286 # define dump_hex(...) ((void)0)
 287 # define dump_tls_record(...) ((void)0)
 288 #endif
 289
 290 void tls_get_random(void *buf, unsigned len)
 291 {
 292         if (len != open_read_close("/dev/urandom", buf, len))
 293                 xfunc_die();
 294 }
 295
 296 /* Nondestructively see the current hash value */
 297 static unsigned sha_peek(md5sha_ctx_t *ctx, void *buffer)
 298 {
 299         md5sha_ctx_t ctx_copy = *ctx; /* struct copy */
 300         return sha_end(&ctx_copy, buffer);
 301 }
 302
 303 static ALWAYS_INLINE unsigned get_handshake_hash(tls_state_t *tls, void *buffer)
 304 {
 305         return sha_peek(&tls->hsd->handshake_hash_ctx, buffer);
 306 }
 307
 308 #if !TLS_DEBUG_HASH
 309 # define hash_handshake(tls, fmt, buffer, len) \
 310          hash_handshake(tls, buffer, len)
 311 #endif
 312 static void hash_handshake(tls_state_t *tls, const char *fmt, const void *buffer, unsigned len)
 313 {
 314         md5sha_hash(&tls->hsd->handshake_hash_ctx, buffer, len);
 315 #if TLS_DEBUG_HASH
 316         {
 317                 uint8_t h[TLS_MAX_MAC_SIZE];
 318                 dump_hex(fmt, buffer, len);
 319                 dbg(" (%u bytes) ", (int)len);
 320                 len = sha_peek(&tls->hsd->handshake_hash_ctx, h);
 321                 if (len == SHA1_OUTSIZE)
 322                         dump_hex("sha1:%s\n", h, len);
 323                 else
 324                 if (len == SHA256_OUTSIZE)
 325                         dump_hex("sha256:%s\n", h, len);
 326                 else
 327                         dump_hex("sha???:%s\n", h, len);
 328         }
 329 #endif
 330 }
 331
 332 // RFC 2104
 333 // HMAC(key, text) based on a hash H (say, sha256) is:
 334 // ipad = [0x36 x INSIZE]
 335 // opad = [0x5c x INSIZE]
 336 // HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text))
 337 //
 338 // H(key XOR opad) and H(key XOR ipad) can be precomputed
 339 // if we often need HMAC hmac with the same key.
 340 //
 341 // text is often given in disjoint pieces.
 342 typedef struct hmac_precomputed {
 343         md5sha_ctx_t hashed_key_xor_ipad;
 344         md5sha_ctx_t hashed_key_xor_opad;
 345 } hmac_precomputed_t;
 346
 347 static unsigned hmac_sha_precomputed_v(
 348                 hmac_precomputed_t *pre,
 349                 uint8_t *out,
 350                 va_list va)
 351 {
 352         uint8_t *text;
 353         unsigned len;
 354
 355         /* pre->hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
 356         /* pre->hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
 357
 358         /* calculate out = H((key XOR ipad) + text) */
 359         while ((text = va_arg(va, uint8_t*)) != NULL) {
 360                 unsigned text_size = va_arg(va, unsigned);
 361                 md5sha_hash(&pre->hashed_key_xor_ipad, text, text_size);
 362         }
 363         len = sha_end(&pre->hashed_key_xor_ipad, out);
 364
 365         /* out = H((key XOR opad) + out) */
 366         md5sha_hash(&pre->hashed_key_xor_opad, out, len);
 367         return sha_end(&pre->hashed_key_xor_opad, out);
 368 }
 369
 370 typedef void md5sha_begin_func(md5sha_ctx_t *ctx) FAST_FUNC;
 371 static void hmac_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size, md5sha_begin_func *begin)
 372 {
 373         uint8_t key_xor_ipad[SHA_INSIZE];
 374         uint8_t key_xor_opad[SHA_INSIZE];
 375         uint8_t tempkey[SHA1_OUTSIZE < SHA256_OUTSIZE ? SHA256_OUTSIZE : SHA1_OUTSIZE];
 376         unsigned i;
 377
 378         // "The authentication key can be of any length up to INSIZE, the
 379         // block length of the hash function.  Applications that use keys longer
 380         // than INSIZE bytes will first hash the key using H and then use the
 381         // resultant OUTSIZE byte string as the actual key to HMAC."
 382         if (key_size > SHA_INSIZE) {
 383                 md5sha_ctx_t ctx;
 384                 begin(&ctx);
 385                 md5sha_hash(&ctx, key, key_size);
 386                 key_size = sha_end(&ctx, tempkey);
 387         }
 388
 389         for (i = 0; i < key_size; i++) {
 390                 key_xor_ipad[i] = key[i] ^ 0x36;
 391                 key_xor_opad[i] = key[i] ^ 0x5c;
 392         }
 393         for (; i < SHA_INSIZE; i++) {
 394                 key_xor_ipad[i] = 0x36;
 395                 key_xor_opad[i] = 0x5c;
 396         }
 397
 398         begin(&pre->hashed_key_xor_ipad);
 399         begin(&pre->hashed_key_xor_opad);
 400         md5sha_hash(&pre->hashed_key_xor_ipad, key_xor_ipad, SHA_INSIZE);
 401         md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
 402 }
 403
 404 static unsigned hmac(tls_state_t *tls, uint8_t *out, uint8_t *key, unsigned key_size, ...)
 405 {
 406         hmac_precomputed_t pre;
 407         va_list va;
 408         unsigned len;
 409
 410         va_start(va, key_size);
 411
 412         hmac_begin(&pre, key, key_size,
 413                         (tls->MAC_size == SHA256_OUTSIZE)
 414                                 ? sha256_begin
 415                                 : sha1_begin
 416         );
 417         len = hmac_sha_precomputed_v(&pre, out, va);
 418
 419         va_end(va);
 420         return len;
 421 }
 422
 423 static unsigned hmac_sha256(/*tls_state_t *tls,*/ uint8_t *out, uint8_t *key, unsigned key_size, ...)
 424 {
 425         hmac_precomputed_t pre;
 426         va_list va;
 427         unsigned len;
 428
 429         va_start(va, key_size);
 430
 431         hmac_begin(&pre, key, key_size, sha256_begin);
 432         len = hmac_sha_precomputed_v(&pre, out, va);
 433
 434         va_end(va);
 435         return len;
 436 }
 437
 438 // RFC 5246:
 439 // 5.  HMAC and the Pseudorandom Function
 440 //...
 441 // In this section, we define one PRF, based on HMAC.  This PRF with the
 442 // SHA-256 hash function is used for all cipher suites defined in this
 443 // document and in TLS documents published prior to this document when
 444 // TLS 1.2 is negotiated.
 445 // ^^^^^^^^^^^^^ IMPORTANT!
 446 //               PRF uses sha256 regardless of cipher (at least for all ciphers
 447 //               defined by RFC5246). It's not sha1 for AES_128_CBC_SHA!
 448 //...
 449 //    P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
 450 //                           HMAC_hash(secret, A(2) + seed) +
 451 //                           HMAC_hash(secret, A(3) + seed) + ...
 452 // where + indicates concatenation.
 453 // A() is defined as:
 454 //    A(0) = seed
 455 //    A(1) = HMAC_hash(secret, A(0)) = HMAC_hash(secret, seed)
 456 //    A(i) = HMAC_hash(secret, A(i-1))
 457 // P_hash can be iterated as many times as necessary to produce the
 458 // required quantity of data.  For example, if P_SHA256 is being used to
 459 // create 80 bytes of data, it will have to be iterated three times
 460 // (through A(3)), creating 96 bytes of output data; the last 16 bytes
 461 // of the final iteration will then be discarded, leaving 80 bytes of
 462 // output data.
 463 //
 464 // TLS's PRF is created by applying P_hash to the secret as:
 465 //
 466 //    PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 467 //
 468 // The label is an ASCII string.
 469 static void prf_hmac_sha256(/*tls_state_t *tls,*/
 470                 uint8_t *outbuf, unsigned outbuf_size,
 471                 uint8_t *secret, unsigned secret_size,
 472                 const char *label,
 473                 uint8_t *seed, unsigned seed_size)
 474 {
 475         uint8_t a[TLS_MAX_MAC_SIZE];
 476         uint8_t *out_p = outbuf;
 477         unsigned label_size = strlen(label);
 478         unsigned MAC_size = SHA256_OUTSIZE;
 479
 480         /* In P_hash() calculation, "seed" is "label + seed": */
 481 #define SEED   label, label_size, seed, seed_size
 482 #define SECRET secret, secret_size
 483 #define A      a, MAC_size
 484
 485         /* A(1) = HMAC_hash(secret, seed) */
 486         hmac_sha256(/*tls,*/ a, SECRET, SEED, NULL);
 487 //TODO: convert hmac to precomputed
 488
 489         for (;;) {
 490                 /* HMAC_hash(secret, A(1) + seed) */
 491                 if (outbuf_size <= MAC_size) {
 492                         /* Last, possibly incomplete, block */
 493                         /* (use a[] as temp buffer) */
 494                         hmac_sha256(/*tls,*/ a, SECRET, A, SEED, NULL);
 495                         memcpy(out_p, a, outbuf_size);
 496                         return;
 497                 }
 498                 /* Not last block. Store directly to result buffer */
 499                 hmac_sha256(/*tls,*/ out_p, SECRET, A, SEED, NULL);
 500                 out_p += MAC_size;
 501                 outbuf_size -= MAC_size;
 502                 /* A(2) = HMAC_hash(secret, A(1)) */
 503                 hmac_sha256(/*tls,*/ a, SECRET, A, NULL);
 504         }
 505 #undef A
 506 #undef SECRET
 507 #undef SEED
 508 }
 509
 510 static void bad_record_die(tls_state_t *tls, const char *expected, int len)
 511 {
 512         bb_error_msg("got bad TLS record (len:%d) while expecting %s", len, expected);
 513         if (len > 0) {
 514                 uint8_t *p = tls->inbuf;
 515                 if (len > 99)
 516                         len = 99; /* don't flood, a few lines should be enough */
 517                 do {
 518                         fprintf(stderr, " %02x", *p++);
 519                         len--;
 520                 } while (len != 0);
 521                 fputc('\n', stderr);
 522         }
 523         xfunc_die();
 524 }
 525
 526 static void tls_error_die(tls_state_t *tls, int line)
 527 {
 528         dump_tls_record(tls->inbuf, tls->ofs_to_buffered + tls->buffered_size);
 529         bb_error_msg_and_die("tls error at line %d cipher:%04x", line, tls->cipher_id);
 530 }
 531 #define tls_error_die(tls) tls_error_die(tls, __LINE__)
 532
 533 #if 0 //UNUSED
 534 static void tls_free_inbuf(tls_state_t *tls)
 535 {
 536         if (tls->buffered_size == 0) {
 537                 free(tls->inbuf);
 538                 tls->inbuf_size = 0;
 539                 tls->inbuf = NULL;
 540         }
 541 }
 542 #endif
 543
 544 static void tls_free_outbuf(tls_state_t *tls)
 545 {
 546         free(tls->outbuf);
 547         tls->outbuf_size = 0;
 548         tls->outbuf = NULL;
 549 }
 550
 551 static void *tls_get_outbuf(tls_state_t *tls, int len)
 552 {
 553         if (len > TLS_MAX_OUTBUF)
 554                 xfunc_die();
 555         len += OUTBUF_PFX + OUTBUF_SFX;
 556         if (tls->outbuf_size < len) {
 557                 tls->outbuf_size = len;
 558                 tls->outbuf = xrealloc(tls->outbuf, len);
 559         }
 560         return tls->outbuf + OUTBUF_PFX;
 561 }
 562
 563 static void xwrite_encrypted(tls_state_t *tls, unsigned size, unsigned type)
 564 {
 565         uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 566         struct record_hdr *xhdr;
 567         uint8_t padding_length;
 568
 569         xhdr = (void*)(buf - RECHDR_LEN);
 570         if (CIPHER_ID1 != TLS_RSA_WITH_NULL_SHA256 /* if "no encryption" can't be selected */
 571          || tls->cipher_id != TLS_RSA_WITH_NULL_SHA256 /* or if it wasn't selected */
 572         ) {
 573                 xhdr = (void*)(buf - RECHDR_LEN - AES_BLOCKSIZE); /* place for IV */
 574         }
 575
 576         xhdr->type = type;
 577         xhdr->proto_maj = TLS_MAJ;
 578         xhdr->proto_min = TLS_MIN;
 579         /* fake unencrypted record len for MAC calculation */
 580         xhdr->len16_hi = size >> 8;
 581         xhdr->len16_lo = size & 0xff;
 582
 583         /* Calculate MAC signature */
 584         hmac(tls, buf + size, /* result */
 585                 tls->client_write_MAC_key, tls->MAC_size,
 586                 &tls->write_seq64_be, sizeof(tls->write_seq64_be),
 587                 xhdr, RECHDR_LEN,
 588                 buf, size,
 589                 NULL
 590         );
 591         tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
 592
 593         size += tls->MAC_size;
 594
 595         // RFC 5246
 596         // 6.2.3.1.  Null or Standard Stream Cipher
 597         //
 598         // Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6)
 599         // convert TLSCompressed.fragment structures to and from stream
 600         // TLSCiphertext.fragment structures.
 601         //
 602         //    stream-ciphered struct {
 603         //        opaque content[TLSCompressed.length];
 604         //        opaque MAC[SecurityParameters.mac_length];
 605         //    } GenericStreamCipher;
 606         //
 607         // The MAC is generated as:
 608         //    MAC(MAC_write_key, seq_num +
 609         //                          TLSCompressed.type +
 610         //                          TLSCompressed.version +
 611         //                          TLSCompressed.length +
 612         //                          TLSCompressed.fragment);
 613         // where "+" denotes concatenation.
 614         // seq_num
 615         //    The sequence number for this record.
 616         // MAC
 617         //    The MAC algorithm specified by SecurityParameters.mac_algorithm.
 618         //
 619         // Note that the MAC is computed before encryption.  The stream cipher
 620         // encrypts the entire block, including the MAC.
 621         //...
 622         // Appendix C.  Cipher Suite Definitions
 623         //...
 624         // MAC       Algorithm    mac_length  mac_key_length
 625         // --------  -----------  ----------  --------------
 626         // SHA       HMAC-SHA1       20            20
 627         // SHA256    HMAC-SHA256     32            32
 628         if (CIPHER_ID1 == TLS_RSA_WITH_NULL_SHA256
 629          && tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
 630         ) {
 631                 /* No encryption, only signing */
 632                 xhdr->len16_hi = size >> 8;
 633                 xhdr->len16_lo = size & 0xff;
 634                 dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 635                 xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 636                 dbg("wrote %u bytes (NULL crypt, SHA256 hash)\n", size);
 637                 return;
 638         }
 639
 640         // 6.2.3.2.  CBC Block Cipher
 641         // For block ciphers (such as 3DES or AES), the encryption and MAC
 642         // functions convert TLSCompressed.fragment structures to and from block
 643         // TLSCiphertext.fragment structures.
 644         //    struct {
 645         //        opaque IV[SecurityParameters.record_iv_length];
 646         //        block-ciphered struct {
 647         //            opaque content[TLSCompressed.length];
 648         //            opaque MAC[SecurityParameters.mac_length];
 649         //            uint8 padding[GenericBlockCipher.padding_length];
 650         //            uint8 padding_length;
 651         //        };
 652         //    } GenericBlockCipher;
 653         //...
 654         // IV
 655         //    The Initialization Vector (IV) SHOULD be chosen at random, and
 656         //    MUST be unpredictable.  Note that in versions of TLS prior to 1.1,
 657         //    there was no IV field (...).  For block ciphers, the IV length is
 658         //    of length SecurityParameters.record_iv_length, which is equal to the
 659         //    SecurityParameters.block_size.
 660         // padding
 661         //    Padding that is added to force the length of the plaintext to be
 662         //    an integral multiple of the block cipher's block length.
 663         // padding_length
 664         //    The padding length MUST be such that the total size of the
 665         //    GenericBlockCipher structure is a multiple of the cipher's block
 666         //    length.  Legal values range from zero to 255, inclusive.
 667         //...
 668         // Appendix C.  Cipher Suite Definitions
 669         //...
 670         //                         Key      IV   Block
 671         // Cipher        Type    Material  Size  Size
 672         // ------------  ------  --------  ----  -----
 673         // AES_128_CBC   Block      16      16     16
 674         // AES_256_CBC   Block      32      16     16
 675
 676         tls_get_random(buf - AES_BLOCKSIZE, AES_BLOCKSIZE); /* IV */
 677         dbg("before crypt: 5 hdr + %u data + %u hash bytes\n",
 678                         size - tls->MAC_size, tls->MAC_size);
 679
 680         /* Fill IV and padding in outbuf */
 681         // RFC is talking nonsense:
 682         //    "Padding that is added to force the length of the plaintext to be
 683         //    an integral multiple of the block cipher's block length."
 684         // WRONG. _padding+padding_length_, not just _padding_,
 685         // pads the data.
 686         // IOW: padding_length is the last byte of padding[] array,
 687         // contrary to what RFC depicts.
 688         //
 689         // What actually happens is that there is always padding.
 690         // If you need one byte to reach BLOCKSIZE, this byte is 0x00.
 691         // If you need two bytes, they are both 0x01.
 692         // If you need three, they are 0x02,0x02,0x02. And so on.
 693         // If you need no bytes to reach BLOCKSIZE, you have to pad a full
 694         // BLOCKSIZE with bytes of value (BLOCKSIZE-1).
 695         // It's ok to have more than minimum padding, but we do minimum.
 696         padding_length = (~size) & (AES_BLOCKSIZE - 1);
 697         do {
 698                 buf[size++] = padding_length; /* padding */
 699         } while ((size & (AES_BLOCKSIZE - 1)) != 0);
 700
 701         /* Encrypt content+MAC+padding in place */
 702         aes_cbc_encrypt(
 703                 tls->client_write_key, tls->key_size, /* selects 128/256 */
 704                 buf - AES_BLOCKSIZE, /* IV */
 705                 buf, size, /* plaintext */
 706                 buf /* ciphertext */
 707         );
 708
 709         /* Write out */
 710         dbg("writing 5 + %u IV + %u encrypted bytes, padding_length:0x%02x\n",
 711                         AES_BLOCKSIZE, size, padding_length);
 712         size += AES_BLOCKSIZE;     /* + IV */
 713         xhdr->len16_hi = size >> 8;
 714         xhdr->len16_lo = size & 0xff;
 715         dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 716         xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 717         dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 718 }
 719
 720 static void xwrite_handshake_record(tls_state_t *tls, unsigned size)
 721 {
 722         //if (!tls->encrypt_on_write) {
 723                 uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 724                 struct record_hdr *xhdr = (void*)(buf - RECHDR_LEN);
 725
 726                 xhdr->type = RECORD_TYPE_HANDSHAKE;
 727                 xhdr->proto_maj = TLS_MAJ;
 728                 xhdr->proto_min = TLS_MIN;
 729                 xhdr->len16_hi = size >> 8;
 730                 xhdr->len16_lo = size & 0xff;
 731                 dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 732                 xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 733                 dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 734         //      return;
 735         //}
 736         //xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
 737 }
 738
 739 static void xwrite_and_update_handshake_hash(tls_state_t *tls, unsigned size)
 740 {
 741         if (!tls->encrypt_on_write) {
 742                 uint8_t *buf;
 743
 744                 xwrite_handshake_record(tls, size);
 745                 /* Handshake hash does not include record headers */
 746                 buf = tls->outbuf + OUTBUF_PFX;
 747                 hash_handshake(tls, ">> hash:%s", buf, size);
 748                 return;
 749         }
 750         xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
 751 }
 752
 753 static int tls_has_buffered_record(tls_state_t *tls)
 754 {
 755         int buffered = tls->buffered_size;
 756         struct record_hdr *xhdr;
 757         int rec_size;
 758
 759         if (buffered < RECHDR_LEN)
 760                 return 0;
 761         xhdr = (void*)(tls->inbuf + tls->ofs_to_buffered);
 762         rec_size = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
 763         if (buffered < rec_size)
 764                 return 0;
 765         return rec_size;
 766 }
 767
 768 static const char *alert_text(int code)
 769 {
 770         switch (code) {
 771         case 20:  return "bad MAC";
 772         case 50:  return "decode error";
 773         case 51:  return "decrypt error";
 774         case 40:  return "handshake failure";
 775         case 112: return "unrecognized name";
 776         }
 777         return itoa(code);
 778 }
 779
 780 static int tls_xread_record(tls_state_t *tls, const char *expected)
 781 {
 782         struct record_hdr *xhdr;
 783         int sz;
 784         int total;
 785         int target;
 786
 787  again:
 788         dbg("ofs_to_buffered:%u buffered_size:%u\n", tls->ofs_to_buffered, tls->buffered_size);
 789         total = tls->buffered_size;
 790         if (total != 0) {
 791                 memmove(tls->inbuf, tls->inbuf + tls->ofs_to_buffered, total);
 792                 //dbg("<< remaining at %d [%d] ", tls->ofs_to_buffered, total);
 793                 //dump_raw_in("<< %s\n", tls->inbuf, total);
 794         }
 795         errno = 0;
 796         target = MAX_INBUF;
 797         for (;;) {
 798                 int rem;
 799
 800                 if (total >= RECHDR_LEN && target == MAX_INBUF) {
 801                         xhdr = (void*)tls->inbuf;
 802                         target = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
 803
 804                         if (target > MAX_INBUF /* malformed input (too long) */
 805                          || xhdr->proto_maj != TLS_MAJ
 806                          || xhdr->proto_min != TLS_MIN
 807                         ) {
 808                                 sz = total < target ? total : target;
 809                                 if (sz > 24)
 810                                         sz = 24; /* don't flood */
 811                                 bad_record_die(tls, expected, sz);
 812                         }
 813                         dbg("xhdr type:%d ver:%d.%d len:%d\n",
 814                                 xhdr->type, xhdr->proto_maj, xhdr->proto_min,
 815                                 0x100 * xhdr->len16_hi + xhdr->len16_lo
 816                         );
 817                 }
 818                 /* if total >= target, we have a full packet (and possibly more)... */
 819                 if (total - target >= 0)
 820                         break;
 821                 /* input buffer is grown only as needed */
 822                 rem = tls->inbuf_size - total;
 823                 if (rem == 0) {
 824                         tls->inbuf_size += MAX_INBUF / 8;
 825                         if (tls->inbuf_size > MAX_INBUF)
 826                                 tls->inbuf_size = MAX_INBUF;
 827                         dbg("inbuf_size:%d\n", tls->inbuf_size);
 828                         rem = tls->inbuf_size - total;
 829                         tls->inbuf = xrealloc(tls->inbuf, tls->inbuf_size);
 830                 }
 831                 sz = safe_read(tls->ifd, tls->inbuf + total, rem);
 832                 if (sz <= 0) {
 833                         if (sz == 0 && total == 0) {
 834                                 /* "Abrupt" EOF, no TLS shutdown (seen from kernel.org) */
 835                                 dbg("EOF (without TLS shutdown) from peer\n");
 836                                 tls->buffered_size = 0;
 837                                 goto end;
 838                         }
 839                         bb_perror_msg_and_die("short read, have only %d", total);
 840                 }
 841                 dump_raw_in("<< %s\n", tls->inbuf + total, sz);
 842                 total += sz;
 843         }
 844         tls->buffered_size = total - target;
 845         tls->ofs_to_buffered = target;
 846         //dbg("<< stashing at %d [%d] ", tls->ofs_to_buffered, tls->buffered_size);
 847         //dump_hex("<< %s\n", tls->inbuf + tls->ofs_to_buffered, tls->buffered_size);
 848
 849         sz = target - RECHDR_LEN;
 850
 851         /* Needs to be decrypted? */
 852         if (tls->min_encrypted_len_on_read > tls->MAC_size) {
 853                 uint8_t *p = tls->inbuf + RECHDR_LEN;
 854                 int padding_len;
 855
 856                 if (sz & (AES_BLOCKSIZE-1)
 857                  || sz < (int)tls->min_encrypted_len_on_read
 858                 ) {
 859                         bb_error_msg_and_die("bad encrypted len:%u < %u",
 860                                 sz, tls->min_encrypted_len_on_read);
 861                 }
 862                 /* Decrypt content+MAC+padding, moving it over IV in the process */
 863                 sz -= AES_BLOCKSIZE; /* we will overwrite IV now */
 864                 aes_cbc_decrypt(
 865                         tls->server_write_key, tls->key_size, /* selects 128/256 */
 866                         p, /* IV */
 867                         p + AES_BLOCKSIZE, sz, /* ciphertext */
 868                         p /* plaintext */
 869                 );
 870                 padding_len = p[sz - 1];
 871                 dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[0], padding_len);
 872                 padding_len++;
 873                 sz -= tls->MAC_size + padding_len; /* drop MAC and padding */
 874                 //if (sz < 0)
 875                 //      bb_error_msg_and_die("bad padding size:%u", padding_len);
 876         } else {
 877                 /* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
 878                 /* else: no encryption yet on input, subtract zero = NOP */
 879                 sz -= tls->min_encrypted_len_on_read;
 880         }
 881         if (sz < 0)
 882                 bb_error_msg_and_die("encrypted data too short");
 883
 884         //dump_hex("<< %s\n", tls->inbuf, RECHDR_LEN + sz);
 885
 886         xhdr = (void*)tls->inbuf;
 887         if (xhdr->type == RECORD_TYPE_ALERT && sz >= 2) {
 888                 uint8_t *p = tls->inbuf + RECHDR_LEN;
 889                 dbg("ALERT size:%d level:%d description:%d\n", sz, p[0], p[1]);
 890                 if (p[0] == 2) { /* fatal */
 891                         bb_error_msg_and_die("TLS %s from peer (alert code %d): %s",
 892                                 "error",
 893                                 p[1], alert_text(p[1])
 894                         );
 895                 }
 896                 if (p[0] == 1) { /* warning */
 897                         if (p[1] == 0) { /* "close_notify" warning: it's EOF */
 898                                 dbg("EOF (TLS encoded) from peer\n");
 899                                 sz = 0;
 900                                 goto end;
 901                         }
 902 //This possibly needs to be cached and shown only if
 903 //a fatal alert follows
 904 //                      bb_error_msg("TLS %s from peer (alert code %d): %s",
 905 //                              "warning",
 906 //                              p[1], alert_text(p[1])
 907 //                      );
 908                         /* discard it, get next record */
 909                         goto again;
 910                 }
 911                 /* p[0] not 1 or 2: not defined in protocol */
 912                 sz = 0;
 913                 goto end;
 914         }
 915
 916         /* RFC 5246 is not saying it explicitly, but sha256 hash
 917          * in our FINISHED record must include data of incoming packets too!
 918          */
 919         if (tls->inbuf[0] == RECORD_TYPE_HANDSHAKE
 920          && tls->MAC_size != 0 /* do we know which hash to use? (server_hello() does not!) */
 921         ) {
 922                 hash_handshake(tls, "<< hash:%s", tls->inbuf + RECHDR_LEN, sz);
 923         }
 924  end:
 925         dbg("got block len:%u\n", sz);
 926         return sz;
 927 }
 928
 929 /*
 930  * DER parsing routines
 931  */
 932 static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end)
 933 {
 934         unsigned len, len1;
 935
 936         if (end - der < 2)
 937                 xfunc_die();
 938 //      if ((der[0] & 0x1f) == 0x1f) /* not single-byte item code? */
 939 //              xfunc_die();
 940
 941         len = der[1]; /* maybe it's short len */
 942         if (len >= 0x80) {
 943                 /* no, it's long */
 944
 945                 if (len == 0x80 || end - der < (int)(len - 0x7e)) {
 946                         /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */
 947                         /* need 3 or 4 bytes for 81, 82 */
 948                         xfunc_die();
 949                 }
 950
 951                 len1 = der[2]; /* if (len == 0x81) it's "ii 81 xx", fetch xx */
 952                 if (len > 0x82) {
 953                         /* >0x82 is "3+ bytes of len", should not happen realistically */
 954                         xfunc_die();
 955                 }
 956                 if (len == 0x82) { /* it's "ii 82 xx yy" */
 957                         len1 = 0x100*len1 + der[3];
 958                         der += 1; /* skip [yy] */
 959                 }
 960                 der += 1; /* skip [xx] */
 961                 len = len1;
 962 //              if (len < 0x80)
 963 //                      xfunc_die(); /* invalid DER: must use short len if can */
 964         }
 965         der += 2; /* skip [code]+[1byte] */
 966
 967         if (end - der < (int)len)
 968                 xfunc_die();
 969         *bodyp = der;
 970
 971         return len;
 972 }
 973
 974 static uint8_t *enter_der_item(uint8_t *der, uint8_t **endp)
 975 {
 976         uint8_t *new_der;
 977         unsigned len = get_der_len(&new_der, der, *endp);
 978         dbg_der("entered der @%p:0x%02x len:%u inner_byte @%p:0x%02x\n", der, der[0], len, new_der, new_der[0]);
 979         /* Move "end" position to cover only this item */
 980         *endp = new_der + len;
 981         return new_der;
 982 }
 983
 984 static uint8_t *skip_der_item(uint8_t *der, uint8_t *end)
 985 {
 986         uint8_t *new_der;
 987         unsigned len = get_der_len(&new_der, der, end);
 988         /* Skip body */
 989         new_der += len;
 990         dbg_der("skipped der 0x%02x, next byte 0x%02x\n", der[0], new_der[0]);
 991         return new_der;
 992 }
 993
 994 static void der_binary_to_pstm(pstm_int *pstm_n, uint8_t *der, uint8_t *end)
 995 {
 996         uint8_t *bin_ptr;
 997         unsigned len = get_der_len(&bin_ptr, der, end);
 998
 999         dbg_der("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]);
1000         pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len);
1001         pstm_read_unsigned_bin(pstm_n, bin_ptr, len);
1002         //return bin + len;
1003 }
1004
1005 static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len)
1006 {
1007 /* Certificate is a DER-encoded data structure. Each DER element has a length,
1008  * which makes it easy to skip over large compound elements of any complexity
1009  * without parsing them. Example: partial decode of kernel.org certificate:
1010  *  SEQ 0x05ac/1452 bytes (Certificate): 308205ac
1011  *    SEQ 0x0494/1172 bytes (tbsCertificate): 30820494
1012  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0] 3 bytes: a003
1013  *        INTEGER (version): 0201 02
1014  *      INTEGER 0x11 bytes (serialNumber): 0211 00 9f85bf664b0cddafca508679501b2be4
1015  *      //^^^^^^note: matrixSSL also allows [ASN_CONTEXT_SPECIFIC | ASN_PRIMITIVE | 2] = 0x82 type
1016  *      SEQ 0x0d bytes (signatureAlgo): 300d
1017  *        OID 9 bytes: 0609 2a864886f70d01010b (OID_SHA256_RSA_SIG 42.134.72.134.247.13.1.1.11)
1018  *        NULL: 0500
1019  *      SEQ 0x5f bytes (issuer): 305f
1020  *        SET 11 bytes: 310b
1021  *          SEQ 9 bytes: 3009
1022  *            OID 3 bytes: 0603 550406
1023  *            Printable string "FR": 1302 4652
1024  *        SET 14 bytes: 310e
1025  *          SEQ 12 bytes: 300c
1026  *            OID 3 bytes: 0603 550408
1027  *            Printable string "Paris": 1305 5061726973
1028  *        SET 14 bytes: 310e
1029  *          SEQ 12 bytes: 300c
1030  *            OID 3 bytes: 0603 550407
1031  *            Printable string "Paris": 1305 5061726973
1032  *        SET 14 bytes: 310e
1033  *          SEQ 12 bytes: 300c
1034  *            OID 3 bytes: 0603 55040a
1035  *            Printable string "Gandi": 1305 47616e6469
1036  *        SET 32 bytes: 3120
1037  *          SEQ 30 bytes: 301e
1038  *            OID 3 bytes: 0603 550403
1039  *            Printable string "Gandi Standard SSL CA 2": 1317 47616e6469205374616e646172642053534c2043412032
1040  *      SEQ 30 bytes (validity): 301e
1041  *        TIME "161011000000Z": 170d 3136313031313030303030305a
1042  *        TIME "191011235959Z": 170d 3139313031313233353935395a
1043  *      SEQ 0x5b/91 bytes (subject): 305b //I did not decode this
1044  *          3121301f060355040b1318446f6d61696e20436f
1045  *          6e74726f6c2056616c6964617465643121301f06
1046  *          0355040b1318506f73697469766553534c204d75
1047  *          6c74692d446f6d61696e31133011060355040313
1048  *          0a6b65726e656c2e6f7267
1049  *      SEQ 0x01a2/418 bytes (subjectPublicKeyInfo): 308201a2
1050  *        SEQ 13 bytes (algorithm): 300d
1051  *          OID 9 bytes: 0609 2a864886f70d010101 (OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1)
1052  *          NULL: 0500
1053  *        BITSTRING 0x018f/399 bytes (publicKey): 0382018f
1054  *          ????: 00
1055  *          //after the zero byte, it appears key itself uses DER encoding:
1056  *          SEQ 0x018a/394 bytes: 3082018a
1057  *            INTEGER 0x0181/385 bytes (modulus): 02820181
1058  *                  00b1ab2fc727a3bef76780c9349bf3
1059  *                  ...24 more blocks of 15 bytes each...
1060  *                  90e895291c6bc8693b65
1061  *            INTEGER 3 bytes (exponent): 0203 010001
1062  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0x3] 0x01e5 bytes (X509v3 extensions): a38201e5
1063  *        SEQ 0x01e1 bytes: 308201e1
1064  *        ...
1065  * Certificate is a sequence of three elements:
1066  *      tbsCertificate (SEQ)
1067  *      signatureAlgorithm (AlgorithmIdentifier)
1068  *      signatureValue (BIT STRING)
1069  *
1070  * In turn, tbsCertificate is a sequence of:
1071  *      version
1072  *      serialNumber
1073  *      signatureAlgo (AlgorithmIdentifier)
1074  *      issuer (Name, has complex structure)
1075  *      validity (Validity, SEQ of two Times)
1076  *      subject (Name)
1077  *      subjectPublicKeyInfo (SEQ)
1078  *      ...
1079  *
1080  * subjectPublicKeyInfo is a sequence of:
1081  *      algorithm (AlgorithmIdentifier)
1082  *      publicKey (BIT STRING)
1083  *
1084  * We need Certificate.tbsCertificate.subjectPublicKeyInfo.publicKey
1085  */
1086         uint8_t *end = der + len;
1087
1088         /* enter "Certificate" item: [der, end) will be only Cert */
1089         der = enter_der_item(der, &end);
1090
1091         /* enter "tbsCertificate" item: [der, end) will be only tbsCert */
1092         der = enter_der_item(der, &end);
1093
1094         /* skip up to subjectPublicKeyInfo */
1095         der = skip_der_item(der, end); /* version */
1096         der = skip_der_item(der, end); /* serialNumber */
1097         der = skip_der_item(der, end); /* signatureAlgo */
1098         der = skip_der_item(der, end); /* issuer */
1099         der = skip_der_item(der, end); /* validity */
1100         der = skip_der_item(der, end); /* subject */
1101
1102         /* enter subjectPublicKeyInfo */
1103         der = enter_der_item(der, &end);
1104         { /* check subjectPublicKeyInfo.algorithm */
1105                 static const uint8_t expected[] = {
1106                         0x30,0x0d, // SEQ 13 bytes
1107                         0x06,0x09, 0x2a,0x86,0x48,0x86,0xf7,0x0d,0x01,0x01,0x01, // OID RSA_KEY_ALG 42.134.72.134.247.13.1.1.1
1108                         //0x05,0x00, // NULL
1109                 };
1110                 if (memcmp(der, expected, sizeof(expected)) != 0)
1111                         bb_error_msg_and_die("not RSA key");
1112         }
1113         /* skip subjectPublicKeyInfo.algorithm */
1114         der = skip_der_item(der, end);
1115         /* enter subjectPublicKeyInfo.publicKey */
1116 //      die_if_not_this_der_type(der, end, 0x03); /* must be BITSTRING */
1117         der = enter_der_item(der, &end);
1118
1119         /* parse RSA key: */
1120 //based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note
1121         dbg("key bytes:%u, first:0x%02x\n", (int)(end - der), der[0]);
1122         if (end - der < 14) xfunc_die();
1123         /* example format:
1124          * ignore bits: 00
1125          * SEQ 0x018a/394 bytes: 3082018a
1126          *   INTEGER 0x0181/385 bytes (modulus): 02820181 XX...XXX
1127          *   INTEGER 3 bytes (exponent): 0203 010001
1128          */
1129         if (*der != 0) /* "ignore bits", should be 0 */
1130                 xfunc_die();
1131         der++;
1132         der = enter_der_item(der, &end); /* enter SEQ */
1133         /* memset(tls->hsd->server_rsa_pub_key, 0, sizeof(tls->hsd->server_rsa_pub_key)); - already is */
1134         der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.N, der, end); /* modulus */
1135         der = skip_der_item(der, end);
1136         der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.e, der, end); /* exponent */
1137         tls->hsd->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->hsd->server_rsa_pub_key.N);
1138         dbg("server_rsa_pub_key.size:%d\n", tls->hsd->server_rsa_pub_key.size);
1139 }
1140
1141 /*
1142  * TLS Handshake routines
1143  */
1144 static int tls_xread_handshake_block(tls_state_t *tls, int min_len)
1145 {
1146         struct record_hdr *xhdr;
1147         int len = tls_xread_record(tls, "handshake record");
1148
1149         xhdr = (void*)tls->inbuf;
1150         if (len < min_len
1151          || xhdr->type != RECORD_TYPE_HANDSHAKE
1152         ) {
1153                 bad_record_die(tls, "handshake record", len);
1154         }
1155         dbg("got HANDSHAKE\n");
1156         return len;
1157 }
1158
1159 static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, unsigned len)
1160 {
1161         struct handshake_hdr {
1162                 uint8_t type;
1163                 uint8_t len24_hi, len24_mid, len24_lo;
1164         } *h = buf;
1165
1166         len -= 4;
1167         h->type = type;
1168         h->len24_hi  = len >> 16;
1169         h->len24_mid = len >> 8;
1170         h->len24_lo  = len & 0xff;
1171 }
1172
1173 static void send_client_hello_and_alloc_hsd(tls_state_t *tls, const char *sni)
1174 {
1175         struct client_hello {
1176                 uint8_t type;
1177                 uint8_t len24_hi, len24_mid, len24_lo;
1178                 uint8_t proto_maj, proto_min;
1179                 uint8_t rand32[32];
1180                 uint8_t session_id_len;
1181                 /* uint8_t session_id[]; */
1182                 uint8_t cipherid_len16_hi, cipherid_len16_lo;
1183                 uint8_t cipherid[2 * (2 + !!CIPHER_ID2)]; /* actually variable */
1184                 uint8_t comprtypes_len;
1185                 uint8_t comprtypes[1]; /* actually variable */
1186                 /* Extensions (SNI shown):
1187                  * hi,lo // len of all extensions
1188                  *   00,00 // extension_type: "Server Name"
1189                  *   00,0e // list len (there can be more than one SNI)
1190                  *     00,0c // len of 1st Server Name Indication
1191                  *       00    // name type: host_name
1192                  *       00,09   // name len
1193                  *       "localhost" // name
1194                  */
1195 // GNU Wget 1.18 to cdn.kernel.org sends these extensions:
1196 // 0055
1197 //   0005 0005 0100000000 - status_request
1198 //   0000 0013 0011 00 000e 63646e 2e 6b65726e656c 2e 6f7267 - server_name
1199 //   ff01 0001 00 - renegotiation_info
1200 //   0023 0000 - session_ticket
1201 //   000a 0008 0006001700180019 - supported_groups
1202 //   000b 0002 0100 - ec_point_formats
1203 //   000d 0016 0014 0401 0403 0501 0503 0601 0603 0301 0303 0201 0203 - signature_algorithms
1204 // wolfssl library sends this option, RFC 7627 (closes a security weakness, some servers may require it. TODO?):
1205 //   0017 0000 - extended master secret
1206         };
1207         struct client_hello *record;
1208         int len;
1209         int sni_len = sni ? strnlen(sni, 127 - 9) : 0;
1210
1211         len = sizeof(*record);
1212         if (sni_len)
1213                 len += 11 + sni_len;
1214         record = tls_get_outbuf(tls, len);
1215         memset(record, 0, len);
1216
1217         fill_handshake_record_hdr(record, HANDSHAKE_CLIENT_HELLO, len);
1218         record->proto_maj = TLS_MAJ;    /* the "requested" version of the protocol, */
1219         record->proto_min = TLS_MIN;    /* can be higher than one in record headers */
1220         tls_get_random(record->rand32, sizeof(record->rand32));
1221         if (TLS_DEBUG_FIXED_SECRETS)
1222                 memset(record->rand32, 0x11, sizeof(record->rand32));
1223         /* record->session_id_len = 0; - already is */
1224
1225         /* record->cipherid_len16_hi = 0; */
1226         record->cipherid_len16_lo = sizeof(record->cipherid);
1227         /* RFC 5746 Renegotiation Indication Extension - some servers will refuse to work with us otherwise */
1228         /*record->cipherid[0] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV >> 8; - zero */
1229         record->cipherid[1] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV & 0xff;
1230         if ((CIPHER_ID1 >> 8) != 0) record->cipherid[2] = CIPHER_ID1 >> 8;
1231         /*************************/ record->cipherid[3] = CIPHER_ID1 & 0xff;
1232 #if CIPHER_ID2
1233         if ((CIPHER_ID2 >> 8) != 0) record->cipherid[4] = CIPHER_ID2 >> 8;
1234         /*************************/ record->cipherid[5] = CIPHER_ID2 & 0xff;
1235 #endif
1236
1237         record->comprtypes_len = 1;
1238         /* record->comprtypes[0] = 0; */
1239
1240         if (sni_len) {
1241                 uint8_t *p = (void*)(record + 1);
1242                 //p[0] = 0;         //
1243                 p[1] = sni_len + 9; //ext_len
1244                 //p[2] = 0;             //
1245                 //p[3] = 0;             //extension_type
1246                 //p[4] = 0;         //
1247                 p[5] = sni_len + 5; //list len
1248                 //p[6] = 0;             //
1249                 p[7] = sni_len + 3;     //len of 1st SNI
1250                 //p[8] = 0;         //name type
1251                 //p[9] = 0;             //
1252                 p[10] = sni_len;        //name len
1253                 memcpy(&p[11], sni, sni_len);
1254         }
1255
1256         dbg(">> CLIENT_HELLO\n");
1257         /* Can hash it only when we know which MAC hash to use */
1258         /*xwrite_and_update_handshake_hash(tls, len); - WRONG! */
1259         xwrite_handshake_record(tls, len);
1260
1261         tls->hsd = xzalloc(sizeof(*tls->hsd) + len);
1262         tls->hsd->saved_client_hello_size = len;
1263         memcpy(tls->hsd->saved_client_hello, record, len);
1264         memcpy(tls->hsd->client_and_server_rand32, record->rand32, sizeof(record->rand32));
1265 }
1266
1267 static void get_server_hello(tls_state_t *tls)
1268 {
1269         struct server_hello {
1270                 struct record_hdr xhdr;
1271                 uint8_t type;
1272                 uint8_t len24_hi, len24_mid, len24_lo;
1273                 uint8_t proto_maj, proto_min;
1274                 uint8_t rand32[32]; /* first 4 bytes are unix time in BE format */
1275                 uint8_t session_id_len;
1276                 uint8_t session_id[32];
1277                 uint8_t cipherid_hi, cipherid_lo;
1278                 uint8_t comprtype;
1279                 /* extensions may follow, but only those which client offered in its Hello */
1280         };
1281
1282         struct server_hello *hp;
1283         uint8_t *cipherid;
1284         unsigned cipher;
1285         int len, len24;
1286
1287         len = tls_xread_handshake_block(tls, 74 - 32);
1288
1289         hp = (void*)tls->inbuf;
1290         // 74 bytes:
1291         // 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|
1292         //SvHl len=70 maj.min unixtime^^^ 28randbytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^ slen sid32bytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cipSel comprSel
1293         if (hp->type != HANDSHAKE_SERVER_HELLO
1294          || hp->len24_hi  != 0
1295          || hp->len24_mid != 0
1296          /* hp->len24_lo checked later */
1297          || hp->proto_maj != TLS_MAJ
1298          || hp->proto_min != TLS_MIN
1299         ) {
1300                 bad_record_die(tls, "'server hello'", len);
1301         }
1302
1303         cipherid = &hp->cipherid_hi;
1304         len24 = hp->len24_lo;
1305         if (hp->session_id_len != 32) {
1306                 if (hp->session_id_len != 0)
1307                         bad_record_die(tls, "'server hello'", len);
1308
1309                 // session_id_len == 0: no session id
1310                 // "The server
1311                 // may return an empty session_id to indicate that the session will
1312                 // not be cached and therefore cannot be resumed."
1313                 cipherid -= 32;
1314                 len24 += 32; /* what len would be if session id would be present */
1315         }
1316
1317         if (len24 < 70
1318 //       || cipherid[0]  != (CIPHER_ID >> 8)
1319 //       || cipherid[1]  != (CIPHER_ID & 0xff)
1320 //       || cipherid[2]  != 0 /* comprtype */
1321         ) {
1322                 bad_record_die(tls, "'server hello'", len);
1323         }
1324         dbg("<< SERVER_HELLO\n");
1325
1326         memcpy(tls->hsd->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32));
1327
1328         tls->cipher_id = cipher = 0x100 * cipherid[0] + cipherid[1];
1329         dbg("server chose cipher %04x\n", cipher);
1330
1331         if (cipher == TLS_RSA_WITH_AES_128_CBC_SHA) {
1332                 tls->key_size = AES128_KEYSIZE;
1333                 tls->MAC_size = SHA1_OUTSIZE;
1334         }
1335         else { /* TLS_RSA_WITH_AES_256_CBC_SHA256 */
1336                 tls->key_size = AES256_KEYSIZE;
1337                 tls->MAC_size = SHA256_OUTSIZE;
1338         }
1339         /* Handshake hash eventually destined to FINISHED record
1340          * is sha256 regardless of cipher
1341          * (at least for all ciphers defined by RFC5246).
1342          * It's not sha1 for AES_128_CBC_SHA - only MAC is sha1, not this hash.
1343          */
1344         sha256_begin(&tls->hsd->handshake_hash_ctx);
1345         hash_handshake(tls, ">> client hello hash:%s",
1346                 tls->hsd->saved_client_hello, tls->hsd->saved_client_hello_size
1347         );
1348         hash_handshake(tls, "<< server hello hash:%s",
1349                 tls->inbuf + RECHDR_LEN, len
1350         );
1351 }
1352
1353 static void get_server_cert(tls_state_t *tls)
1354 {
1355         struct record_hdr *xhdr;
1356         uint8_t *certbuf;
1357         int len, len1;
1358
1359         len = tls_xread_handshake_block(tls, 10);
1360
1361         xhdr = (void*)tls->inbuf;
1362         certbuf = (void*)(xhdr + 1);
1363         if (certbuf[0] != HANDSHAKE_CERTIFICATE)
1364                 bad_record_die(tls, "certificate", len);
1365         dbg("<< CERTIFICATE\n");
1366         // 4392 bytes:
1367         // 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...
1368         //Cert len=4388 ChainLen CertLen^ DER encoded X509 starts here. openssl x509 -in FILE -inform DER -noout -text
1369         len1 = get24be(certbuf + 1);
1370         if (len1 > len - 4) tls_error_die(tls);
1371         len = len1;
1372         len1 = get24be(certbuf + 4);
1373         if (len1 > len - 3) tls_error_die(tls);
1374         len = len1;
1375         len1 = get24be(certbuf + 7);
1376         if (len1 > len - 3) tls_error_die(tls);
1377         len = len1;
1378
1379         if (len)
1380                 find_key_in_der_cert(tls, certbuf + 10, len);
1381 }
1382
1383 static void send_empty_client_cert(tls_state_t *tls)
1384 {
1385         struct client_empty_cert {
1386                 uint8_t type;
1387                 uint8_t len24_hi, len24_mid, len24_lo;
1388                 uint8_t cert_chain_len24_hi, cert_chain_len24_mid, cert_chain_len24_lo;
1389         };
1390         struct client_empty_cert *record;
1391
1392         record = tls_get_outbuf(tls, sizeof(*record));
1393 //FIXME: can just memcpy a ready-made one.
1394         fill_handshake_record_hdr(record, HANDSHAKE_CERTIFICATE, sizeof(*record));
1395         record->cert_chain_len24_hi = 0;
1396         record->cert_chain_len24_mid = 0;
1397         record->cert_chain_len24_lo = 0;
1398
1399         dbg(">> CERTIFICATE\n");
1400         xwrite_and_update_handshake_hash(tls, sizeof(*record));
1401 }
1402
1403 static void send_client_key_exchange(tls_state_t *tls)
1404 {
1405         struct client_key_exchange {
1406                 uint8_t type;
1407                 uint8_t len24_hi, len24_mid, len24_lo;
1408                 /* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */
1409                 uint8_t keylen16_hi, keylen16_lo;
1410                 uint8_t key[4 * 1024]; // size??
1411         };
1412 //FIXME: better size estimate
1413         struct client_key_exchange *record = tls_get_outbuf(tls, sizeof(*record));
1414         uint8_t rsa_premaster[RSA_PREMASTER_SIZE];
1415         int len;
1416
1417         tls_get_random(rsa_premaster, sizeof(rsa_premaster));
1418         if (TLS_DEBUG_FIXED_SECRETS)
1419                 memset(rsa_premaster, 0x44, sizeof(rsa_premaster));
1420         // RFC 5246
1421         // "Note: The version number in the PreMasterSecret is the version
1422         // offered by the client in the ClientHello.client_version, not the
1423         // version negotiated for the connection."
1424         rsa_premaster[0] = TLS_MAJ;
1425         rsa_premaster[1] = TLS_MIN;
1426         dump_hex("premaster:%s\n", rsa_premaster, sizeof(rsa_premaster));
1427         len = psRsaEncryptPub(/*pool:*/ NULL,
1428                 /* psRsaKey_t* */ &tls->hsd->server_rsa_pub_key,
1429                 rsa_premaster, /*inlen:*/ sizeof(rsa_premaster),
1430                 record->key, sizeof(record->key),
1431                 data_param_ignored
1432         );
1433         record->keylen16_hi = len >> 8;
1434         record->keylen16_lo = len & 0xff;
1435         len += 2;
1436         record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
1437         record->len24_hi  = 0;
1438         record->len24_mid = len >> 8;
1439         record->len24_lo  = len & 0xff;
1440         len += 4;
1441
1442         dbg(">> CLIENT_KEY_EXCHANGE\n");
1443         xwrite_and_update_handshake_hash(tls, len);
1444
1445         // RFC 5246
1446         // For all key exchange methods, the same algorithm is used to convert
1447         // the pre_master_secret into the master_secret.  The pre_master_secret
1448         // should be deleted from memory once the master_secret has been
1449         // computed.
1450         //      master_secret = PRF(pre_master_secret, "master secret",
1451         //                          ClientHello.random + ServerHello.random)
1452         //                          [0..47];
1453         // The master secret is always exactly 48 bytes in length.  The length
1454         // of the premaster secret will vary depending on key exchange method.
1455         prf_hmac_sha256(/*tls,*/
1456                 tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1457                 rsa_premaster, sizeof(rsa_premaster),
1458                 "master secret",
1459                 tls->hsd->client_and_server_rand32, sizeof(tls->hsd->client_and_server_rand32)
1460         );
1461         dump_hex("master secret:%s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
1462
1463         // RFC 5246
1464         // 6.3.  Key Calculation
1465         //
1466         // The Record Protocol requires an algorithm to generate keys required
1467         // by the current connection state (see Appendix A.6) from the security
1468         // parameters provided by the handshake protocol.
1469         //
1470         // The master secret is expanded into a sequence of secure bytes, which
1471         // is then split to a client write MAC key, a server write MAC key, a
1472         // client write encryption key, and a server write encryption key.  Each
1473         // of these is generated from the byte sequence in that order.  Unused
1474         // values are empty.  Some AEAD ciphers may additionally require a
1475         // client write IV and a server write IV (see Section 6.2.3.3).
1476         //
1477         // When keys and MAC keys are generated, the master secret is used as an
1478         // entropy source.
1479         //
1480         // To generate the key material, compute
1481         //
1482         //    key_block = PRF(SecurityParameters.master_secret,
1483         //                    "key expansion",
1484         //                    SecurityParameters.server_random +
1485         //                    SecurityParameters.client_random);
1486         //
1487         // until enough output has been generated.  Then, the key_block is
1488         // partitioned as follows:
1489         //
1490         //    client_write_MAC_key[SecurityParameters.mac_key_length]
1491         //    server_write_MAC_key[SecurityParameters.mac_key_length]
1492         //    client_write_key[SecurityParameters.enc_key_length]
1493         //    server_write_key[SecurityParameters.enc_key_length]
1494         //    client_write_IV[SecurityParameters.fixed_iv_length]
1495         //    server_write_IV[SecurityParameters.fixed_iv_length]
1496         {
1497                 uint8_t tmp64[64];
1498
1499                 /* make "server_rand32 + client_rand32" */
1500                 memcpy(&tmp64[0] , &tls->hsd->client_and_server_rand32[32], 32);
1501                 memcpy(&tmp64[32], &tls->hsd->client_and_server_rand32[0] , 32);
1502
1503                 prf_hmac_sha256(/*tls,*/
1504                         tls->client_write_MAC_key, 2 * (tls->MAC_size + tls->key_size),
1505                         // also fills:
1506                         // server_write_MAC_key[]
1507                         // client_write_key[]
1508                         // server_write_key[]
1509                         tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1510                         "key expansion",
1511                         tmp64, 64
1512                 );
1513                 tls->client_write_key = tls->client_write_MAC_key + (2 * tls->MAC_size);
1514                 tls->server_write_key = tls->client_write_key + tls->key_size;
1515                 dump_hex("client_write_MAC_key:%s\n",
1516                         tls->client_write_MAC_key, tls->MAC_size
1517                 );
1518                 dump_hex("client_write_key:%s\n",
1519                         tls->client_write_key, tls->key_size
1520                 );
1521         }
1522 }
1523
1524 static const uint8_t rec_CHANGE_CIPHER_SPEC[] = {
1525         RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01,
1526         01
1527 };
1528
1529 static void send_change_cipher_spec(tls_state_t *tls)
1530 {
1531         dbg(">> CHANGE_CIPHER_SPEC\n");
1532         xwrite(tls->ofd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC));
1533 }
1534
1535 // 7.4.9.  Finished
1536 // A Finished message is always sent immediately after a change
1537 // cipher spec message to verify that the key exchange and
1538 // authentication processes were successful.  It is essential that a
1539 // change cipher spec message be received between the other handshake
1540 // messages and the Finished message.
1541 //...
1542 // The Finished message is the first one protected with the just
1543 // negotiated algorithms, keys, and secrets.  Recipients of Finished
1544 // messages MUST verify that the contents are correct.  Once a side
1545 // has sent its Finished message and received and validated the
1546 // Finished message from its peer, it may begin to send and receive
1547 // application data over the connection.
1548 //...
1549 // struct {
1550 //     opaque verify_data[verify_data_length];
1551 // } Finished;
1552 //
1553 // verify_data
1554 //    PRF(master_secret, finished_label, Hash(handshake_messages))
1555 //       [0..verify_data_length-1];
1556 //
1557 // finished_label
1558 //    For Finished messages sent by the client, the string
1559 //    "client finished".  For Finished messages sent by the server,
1560 //    the string "server finished".
1561 //
1562 // Hash denotes a Hash of the handshake messages.  For the PRF
1563 // defined in Section 5, the Hash MUST be the Hash used as the basis
1564 // for the PRF.  Any cipher suite which defines a different PRF MUST
1565 // also define the Hash to use in the Finished computation.
1566 //
1567 // In previous versions of TLS, the verify_data was always 12 octets
1568 // long.  In the current version of TLS, it depends on the cipher
1569 // suite.  Any cipher suite which does not explicitly specify
1570 // verify_data_length has a verify_data_length equal to 12.  This
1571 // includes all existing cipher suites.
1572 static void send_client_finished(tls_state_t *tls)
1573 {
1574         struct finished {
1575                 uint8_t type;
1576                 uint8_t len24_hi, len24_mid, len24_lo;
1577                 uint8_t prf_result[12];
1578         };
1579         struct finished *record = tls_get_outbuf(tls, sizeof(*record));
1580         uint8_t handshake_hash[TLS_MAX_MAC_SIZE];
1581         unsigned len;
1582
1583         fill_handshake_record_hdr(record, HANDSHAKE_FINISHED, sizeof(*record));
1584
1585         len = get_handshake_hash(tls, handshake_hash);
1586         prf_hmac_sha256(/*tls,*/
1587                 record->prf_result, sizeof(record->prf_result),
1588                 tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1589                 "client finished",
1590                 handshake_hash, len
1591         );
1592         dump_hex("from secret: %s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
1593         dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1);
1594         dump_hex("%s\n", handshake_hash, sizeof(handshake_hash));
1595         dump_hex("=> digest: %s\n", record->prf_result, sizeof(record->prf_result));
1596
1597         dbg(">> FINISHED\n");
1598         xwrite_encrypted(tls, sizeof(*record), RECORD_TYPE_HANDSHAKE);
1599 }
1600
1601 void FAST_FUNC tls_handshake(tls_state_t *tls, const char *sni)
1602 {
1603         // Client              RFC 5246                Server
1604         // (*) - optional messages, not always sent
1605         //
1606         // ClientHello          ------->
1607         //                                        ServerHello
1608         //                                       Certificate*
1609         //                                 ServerKeyExchange*
1610         //                                CertificateRequest*
1611         //                      <-------      ServerHelloDone
1612         // Certificate*
1613         // ClientKeyExchange
1614         // CertificateVerify*
1615         // [ChangeCipherSpec]
1616         // Finished             ------->
1617         //                                 [ChangeCipherSpec]
1618         //                      <-------             Finished
1619         // Application Data     <------>     Application Data
1620         int len;
1621         int got_cert_req;
1622
1623         send_client_hello_and_alloc_hsd(tls, sni);
1624         get_server_hello(tls);
1625
1626         // RFC 5246
1627         // The server MUST send a Certificate message whenever the agreed-
1628         // upon key exchange method uses certificates for authentication
1629         // (this includes all key exchange methods defined in this document
1630         // except DH_anon).  This message will always immediately follow the
1631         // ServerHello message.
1632         //
1633         // IOW: in practice, Certificate *always* follows.
1634         // (for example, kernel.org does not even accept DH_anon cipher id)
1635         get_server_cert(tls);
1636
1637         len = tls_xread_handshake_block(tls, 4);
1638         if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_SERVER_KEY_EXCHANGE) {
1639                 // 459 bytes:
1640                 // 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...
1641                 //SvKey len=455^
1642                 // with TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: 461 bytes:
1643                 // 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...
1644                 dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len);
1645 //probably need to save it
1646                 len = tls_xread_handshake_block(tls, 4);
1647         }
1648
1649         got_cert_req = (tls->inbuf[RECHDR_LEN] == HANDSHAKE_CERTIFICATE_REQUEST);
1650         if (got_cert_req) {
1651                 dbg("<< CERTIFICATE_REQUEST\n");
1652                 // RFC 5246: "If no suitable certificate is available,
1653                 // the client MUST send a certificate message containing no
1654                 // certificates.  That is, the certificate_list structure has a
1655                 // length of zero. ...
1656                 // Client certificates are sent using the Certificate structure
1657                 // defined in Section 7.4.2."
1658                 // (i.e. the same format as server certs)
1659
1660                 /*send_empty_client_cert(tls); - WRONG (breaks handshake hash calc) */
1661                 /* need to hash _all_ server replies first, up to ServerHelloDone */
1662                 len = tls_xread_handshake_block(tls, 4);
1663         }
1664
1665         if (tls->inbuf[RECHDR_LEN] != HANDSHAKE_SERVER_HELLO_DONE) {
1666                 bad_record_die(tls, "'server hello done'", len);
1667         }
1668         // 0e 000000 (len:0)
1669         dbg("<< SERVER_HELLO_DONE\n");
1670
1671         if (got_cert_req)
1672                 send_empty_client_cert(tls);
1673
1674         send_client_key_exchange(tls);
1675
1676         send_change_cipher_spec(tls);
1677         /* from now on we should send encrypted */
1678         /* tls->write_seq64_be = 0; - already is */
1679         tls->encrypt_on_write = 1;
1680
1681         send_client_finished(tls);
1682
1683         /* Get CHANGE_CIPHER_SPEC */
1684         len = tls_xread_record(tls, "switch to encrypted traffic");
1685         if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0)
1686                 bad_record_die(tls, "switch to encrypted traffic", len);
1687         dbg("<< CHANGE_CIPHER_SPEC\n");
1688         if (CIPHER_ID1 == TLS_RSA_WITH_NULL_SHA256
1689          && tls->cipher_id == TLS_RSA_WITH_NULL_SHA256
1690         ) {
1691                 tls->min_encrypted_len_on_read = tls->MAC_size;
1692         } else {
1693                 unsigned mac_blocks = (unsigned)(tls->MAC_size + AES_BLOCKSIZE-1) / AES_BLOCKSIZE;
1694                 /* all incoming packets now should be encrypted and have
1695                  * at least IV + (MAC padded to blocksize):
1696                  */
1697                 tls->min_encrypted_len_on_read = AES_BLOCKSIZE + (mac_blocks * AES_BLOCKSIZE);
1698                 dbg("min_encrypted_len_on_read: %u", tls->min_encrypted_len_on_read);
1699         }
1700
1701         /* Get (encrypted) FINISHED from the server */
1702         len = tls_xread_record(tls, "'server finished'");
1703         if (len < 4 || tls->inbuf[RECHDR_LEN] != HANDSHAKE_FINISHED)
1704                 bad_record_die(tls, "'server finished'", len);
1705         dbg("<< FINISHED\n");
1706         /* application data can be sent/received */
1707
1708         /* free handshake data */
1709 //      if (PARANOIA)
1710 //              memset(tls->hsd, 0, tls->hsd->hsd_size);
1711         free(tls->hsd);
1712         tls->hsd = NULL;
1713 }
1714
1715 static void tls_xwrite(tls_state_t *tls, int len)
1716 {
1717         dbg(">> DATA\n");
1718         xwrite_encrypted(tls, len, RECORD_TYPE_APPLICATION_DATA);
1719 }
1720
1721 // To run a test server using openssl:
1722 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
1723 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1
1724 //
1725 // Unencryped SHA256 example:
1726 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
1727 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL
1728 // openssl s_client -connect 127.0.0.1:4433 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL-SHA256
1729
1730 void FAST_FUNC tls_run_copy_loop(tls_state_t *tls, unsigned flags)
1731 {
1732         int inbuf_size;
1733         const int INBUF_STEP = 4 * 1024;
1734         struct pollfd pfds[2];
1735
1736         pfds[0].fd = STDIN_FILENO;
1737         pfds[0].events = POLLIN;
1738         pfds[1].fd = tls->ifd;
1739         pfds[1].events = POLLIN;
1740
1741         inbuf_size = INBUF_STEP;
1742         for (;;) {
1743                 int nread;
1744
1745                 if (safe_poll(pfds, 2, -1) < 0)
1746                         bb_perror_msg_and_die("poll");
1747
1748                 if (pfds[0].revents) {
1749                         void *buf;
1750
1751                         dbg("STDIN HAS DATA\n");
1752                         buf = tls_get_outbuf(tls, inbuf_size);
1753                         nread = safe_read(STDIN_FILENO, buf, inbuf_size);
1754                         if (nread < 1) {
1755                                 /* We'd want to do this: */
1756                                 /* Close outgoing half-connection so they get EOF,
1757                                  * but leave incoming alone so we can see response
1758                                  */
1759                                 //shutdown(tls->ofd, SHUT_WR);
1760                                 /* But TLS has no way to encode this,
1761                                  * doubt it's ok to do it "raw"
1762                                  */
1763                                 pfds[0].fd = -1;
1764                                 tls_free_outbuf(tls); /* mem usage optimization */
1765                                 if (flags & TLSLOOP_EXIT_ON_LOCAL_EOF)
1766                                         break;
1767                         } else {
1768                                 if (nread == inbuf_size) {
1769                                         /* TLS has per record overhead, if input comes fast,
1770                                          * read, encrypt and send bigger chunks
1771                                          */
1772                                         inbuf_size += INBUF_STEP;
1773                                         if (inbuf_size > TLS_MAX_OUTBUF)
1774                                                 inbuf_size = TLS_MAX_OUTBUF;
1775                                 }
1776                                 tls_xwrite(tls, nread);
1777                         }
1778                 }
1779                 if (pfds[1].revents) {
1780                         dbg("NETWORK HAS DATA\n");
1781  read_record:
1782                         nread = tls_xread_record(tls, "encrypted data");
1783                         if (nread < 1) {
1784                                 /* TLS protocol has no real concept of one-sided shutdowns:
1785                                  * if we get "TLS EOF" from the peer, writes will fail too
1786                                  */
1787                                 //pfds[1].fd = -1;
1788                                 //close(STDOUT_FILENO);
1789                                 //tls_free_inbuf(tls); /* mem usage optimization */
1790                                 //continue;
1791                                 break;
1792                         }
1793                         if (tls->inbuf[0] != RECORD_TYPE_APPLICATION_DATA)
1794                                 bad_record_die(tls, "encrypted data", nread);
1795                         xwrite(STDOUT_FILENO, tls->inbuf + RECHDR_LEN, nread);
1796                         /* We may already have a complete next record buffered,
1797                          * can process it without network reads (and possible blocking)
1798                          */
1799                         if (tls_has_buffered_record(tls))
1800                                 goto read_record;
1801                 }
1802         }
1803 }