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 #define TLS_DEBUG      0
  22 #define TLS_DEBUG_HASH 0
  23 #define TLS_DEBUG_DER  0
  24 #define TLS_DEBUG_FIXED_SECRETS 0
  25 #if 0
  26 # define dump_raw_out(...) dump_hex(__VA_ARGS__)
  27 #else
  28 # define dump_raw_out(...) ((void)0)
  29 #endif
  30 #if 0
  31 # define dump_raw_in(...) dump_hex(__VA_ARGS__)
  32 #else
  33 # define dump_raw_in(...) ((void)0)
  34 #endif
  35
  36 #if TLS_DEBUG
  37 # define dbg(...) fprintf(stderr, __VA_ARGS__)
  38 #else
  39 # define dbg(...) ((void)0)
  40 #endif
  41
  42 #if TLS_DEBUG_DER
  43 # define dbg_der(...) fprintf(stderr, __VA_ARGS__)
  44 #else
  45 # define dbg_der(...) ((void)0)
  46 #endif
  47
  48 #define RECORD_TYPE_CHANGE_CIPHER_SPEC  20
  49 #define RECORD_TYPE_ALERT               21
  50 #define RECORD_TYPE_HANDSHAKE           22
  51 #define RECORD_TYPE_APPLICATION_DATA    23
  52
  53 #define HANDSHAKE_HELLO_REQUEST         0
  54 #define HANDSHAKE_CLIENT_HELLO          1
  55 #define HANDSHAKE_SERVER_HELLO          2
  56 #define HANDSHAKE_HELLO_VERIFY_REQUEST  3
  57 #define HANDSHAKE_NEW_SESSION_TICKET    4
  58 #define HANDSHAKE_CERTIFICATE           11
  59 #define HANDSHAKE_SERVER_KEY_EXCHANGE   12
  60 #define HANDSHAKE_CERTIFICATE_REQUEST   13
  61 #define HANDSHAKE_SERVER_HELLO_DONE     14
  62 #define HANDSHAKE_CERTIFICATE_VERIFY    15
  63 #define HANDSHAKE_CLIENT_KEY_EXCHANGE   16
  64 #define HANDSHAKE_FINISHED              20
  65
  66 #define SSL_NULL_WITH_NULL_NULL                 0x0000
  67 #define SSL_RSA_WITH_NULL_MD5                   0x0001
  68 #define SSL_RSA_WITH_NULL_SHA                   0x0002
  69 #define SSL_RSA_WITH_RC4_128_MD5                0x0004
  70 #define SSL_RSA_WITH_RC4_128_SHA                0x0005
  71 #define SSL_RSA_WITH_3DES_EDE_CBC_SHA           0x000A  /* 10 */
  72 #define TLS_RSA_WITH_AES_128_CBC_SHA            0x002F  /* 47 */
  73 #define TLS_RSA_WITH_AES_256_CBC_SHA            0x0035  /* 53 */
  74 #define TLS_RSA_WITH_NULL_SHA256                0x003B  /* 59 */
  75
  76 #define TLS_EMPTY_RENEGOTIATION_INFO_SCSV       0x00FF
  77
  78 #define TLS_RSA_WITH_IDEA_CBC_SHA               0x0007  /* 7 */
  79 #define SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA       0x0016  /* 22 */
  80 #define SSL_DH_anon_WITH_RC4_128_MD5            0x0018  /* 24 */
  81 #define SSL_DH_anon_WITH_3DES_EDE_CBC_SHA       0x001B  /* 27 */
  82 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA        0x0033  /* 51 */
  83 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA        0x0039  /* 57 */
  84 #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256     0x0067  /* 103 */
  85 #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256     0x006B  /* 107 */
  86 #define TLS_DH_anon_WITH_AES_128_CBC_SHA        0x0034  /* 52 */
  87 #define TLS_DH_anon_WITH_AES_256_CBC_SHA        0x003A  /* 58 */
  88 #define TLS_RSA_WITH_AES_128_CBC_SHA256         0x003C  /* 60 */
  89 #define TLS_RSA_WITH_AES_256_CBC_SHA256         0x003D  /* 61 */
  90 #define TLS_RSA_WITH_SEED_CBC_SHA               0x0096  /* 150 */
  91 #define TLS_PSK_WITH_AES_128_CBC_SHA            0x008C  /* 140 */
  92 #define TLS_PSK_WITH_AES_128_CBC_SHA256         0x00AE  /* 174 */
  93 #define TLS_PSK_WITH_AES_256_CBC_SHA384         0x00AF  /* 175 */
  94 #define TLS_PSK_WITH_AES_256_CBC_SHA            0x008D  /* 141 */
  95 #define TLS_DHE_PSK_WITH_AES_128_CBC_SHA        0x0090  /* 144 */
  96 #define TLS_DHE_PSK_WITH_AES_256_CBC_SHA        0x0091  /* 145 */
  97 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA     0xC004  /* 49156 */
  98 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA     0xC005  /* 49157 */
  99 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA    0xC009  /* 49161 */
 100 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA    0xC00A  /* 49162 */
 101 #define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA     0xC012  /* 49170 */
 102 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA      0xC013  /* 49171 */
 103 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA      0xC014  /* 49172 */
 104 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA       0xC00E  /* 49166 */
 105 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA       0xC00F  /* 49167 */
 106 #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 0xC023  /* 49187 */
 107 #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024  /* 49188 */
 108 #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256  0xC025  /* 49189 */
 109 #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384  0xC026  /* 49190 */
 110 #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256   0xC027  /* 49191 */
 111 #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384   0xC028  /* 49192 */
 112 #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256    0xC029  /* 49193 */
 113 #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384    0xC02A  /* 49194 */
 114
 115 /* RFC 5288 "AES Galois Counter Mode (GCM) Cipher Suites for TLS" */
 116 #define TLS_RSA_WITH_AES_128_GCM_SHA256         0x009C  /* 156 */
 117 #define TLS_RSA_WITH_AES_256_GCM_SHA384         0x009D  /* 157 */
 118 #define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B  /* 49195 */
 119 #define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C  /* 49196 */
 120 #define TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256  0xC02D  /* 49197 */
 121 #define TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384  0xC02E  /* 49198 */
 122 #define TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256   0xC02F  /* 49199 */
 123 #define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384   0xC030  /* 49200 */
 124 #define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256    0xC031  /* 49201 */
 125 #define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384    0xC032  /* 49202 */
 126
 127 //Tested against kernel.org:
 128 //TLS 1.2
 129 #define TLS_MAJ 3
 130 #define TLS_MIN 3
 131 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE *** matrixssl uses this on my box
 132 //#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE
 133 //#define CIPHER_ID TLS_DH_anon_WITH_AES_256_CBC_SHA // SSL_ALERT_HANDSHAKE_FAILURE
 134 //^^^^^^^^^^^^^^^^^^^^^^^ (tested b/c this one doesn't req server certs... no luck, server refuses it)
 135 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 // SSL_ALERT_HANDSHAKE_FAILURE
 136 //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
 137 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 // ok, recvs SERVER_KEY_EXCHANGE
 138 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
 139 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384
 140 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
 141 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
 142 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE
 143 //#define CIPHER_ID TLS_RSA_WITH_AES_256_GCM_SHA384 // ok, no SERVER_KEY_EXCHANGE
 144 //#define CIPHER_ID TLS_RSA_WITH_AES_128_GCM_SHA256 // ok, no SERVER_KEY_EXCHANGE *** select this?
 145
 146 // works against "openssl s_server -cipher NULL"
 147 // and against wolfssl-3.9.10-stable/examples/server/server.c:
 148 //#define CIPHER_ID TLS_RSA_WITH_NULL_SHA256 // for testing (does everything except encrypting)
 149
 150 // works against wolfssl-3.9.10-stable/examples/server/server.c
 151 // works for kernel.org
 152 // does not work for cdn.kernel.org (e.g. downloading an actual tarball, not a web page)
 153 //  getting alert 40 "handshake failure" at once
 154 //  with GNU Wget 1.18, they agree on TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xC02F) cipher
 155 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-SHA256
 156 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES256-GCM-SHA384
 157 //  fail: openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA256
 158 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-GCM-SHA256
 159 //  ok:   openssl s_client -connect cdn.kernel.org:443 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher AES128-SHA
 160 //        (TLS_RSA_WITH_AES_128_CBC_SHA - in TLS 1.2 it's mandated to be always supported)
 161 #define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // no SERVER_KEY_EXCHANGE from peer
 162
 163 enum {
 164         RSA_PREMASTER_SIZE = 48,
 165
 166         RECHDR_LEN = 5,
 167
 168         MAX_TLS_RECORD = (1 << 14),
 169         /* 8 = 3+5. 3 extra bytes result in record data being 32-bit aligned */
 170         OUTBUF_PFX = 8 + AES_BLOCKSIZE, /* header + IV */
 171         OUTBUF_SFX = SHA256_OUTSIZE + AES_BLOCKSIZE, /* MAC + padding */
 172         MAX_OUTBUF = MAX_TLS_RECORD - OUTBUF_PFX - OUTBUF_SFX,
 173
 174         // RFC 5246
 175         // | 6.2.1. Fragmentation
 176         // |  The record layer fragments information blocks into TLSPlaintext
 177         // |  records carrying data in chunks of 2^14 bytes or less.  Client
 178         // |  message boundaries are not preserved in the record layer (i.e.,
 179         // |  multiple client messages of the same ContentType MAY be coalesced
 180         // |  into a single TLSPlaintext record, or a single message MAY be
 181         // |  fragmented across several records)
 182         // |...
 183         // |  length
 184         // |    The length (in bytes) of the following TLSPlaintext.fragment.
 185         // |    The length MUST NOT exceed 2^14.
 186         // |...
 187         // | 6.2.2. Record Compression and Decompression
 188         // |...
 189         // |  Compression must be lossless and may not increase the content length
 190         // |  by more than 1024 bytes.  If the decompression function encounters a
 191         // |  TLSCompressed.fragment that would decompress to a length in excess of
 192         // |  2^14 bytes, it MUST report a fatal decompression failure error.
 193         // |...
 194         // |  length
 195         // |    The length (in bytes) of the following TLSCompressed.fragment.
 196         // |    The length MUST NOT exceed 2^14 + 1024.
 197         // |...
 198         // | 6.2.3.  Record Payload Protection
 199         // |  The encryption and MAC functions translate a TLSCompressed
 200         // |  structure into a TLSCiphertext.  The decryption functions reverse
 201         // |  the process.  The MAC of the record also includes a sequence
 202         // |  number so that missing, extra, or repeated messages are
 203         // |  detectable.
 204         // |...
 205         // |  length
 206         // |    The length (in bytes) of the following TLSCiphertext.fragment.
 207         // |    The length MUST NOT exceed 2^14 + 2048.
 208         MAX_INBUF = (1 << 14) + 2048,
 209 };
 210
 211 struct record_hdr {
 212         uint8_t type;
 213         uint8_t proto_maj, proto_min;
 214         uint8_t len16_hi, len16_lo;
 215 };
 216
 217 struct tls_handshake_data {
 218         sha256_ctx_t handshake_sha256_ctx;
 219         uint8_t client_and_server_rand32[2 * 32];
 220         uint8_t master_secret[48];
 221 //TODO: store just the DER key here, parse/use/delete it when sending client key
 222 //this way it will stay key type agnostic here.
 223         psRsaKey_t server_rsa_pub_key;
 224 };
 225
 226
 227 static unsigned get24be(const uint8_t *p)
 228 {
 229         return 0x100*(0x100*p[0] + p[1]) + p[2];
 230 }
 231
 232 #if TLS_DEBUG
 233 static void dump_hex(const char *fmt, const void *vp, int len)
 234 {
 235         char hexbuf[32 * 1024 + 4];
 236         const uint8_t *p = vp;
 237
 238         bin2hex(hexbuf, (void*)p, len)[0] = '\0';
 239         dbg(fmt, hexbuf);
 240 }
 241
 242 static void dump_tls_record(const void *vp, int len)
 243 {
 244         const uint8_t *p = vp;
 245
 246         while (len > 0) {
 247                 unsigned xhdr_len;
 248                 if (len < RECHDR_LEN) {
 249                         dump_hex("< |%s|\n", p, len);
 250                         return;
 251                 }
 252                 xhdr_len = 0x100*p[3] + p[4];
 253                 dbg("< hdr_type:%u ver:%u.%u len:%u", p[0], p[1], p[2], xhdr_len);
 254                 p += RECHDR_LEN;
 255                 len -= RECHDR_LEN;
 256                 if (len >= 4 && p[-RECHDR_LEN] == RECORD_TYPE_HANDSHAKE) {
 257                         unsigned len24 = get24be(p + 1);
 258                         dbg(" type:%u len24:%u", p[0], len24);
 259                 }
 260                 if (xhdr_len > len)
 261                         xhdr_len = len;
 262                 dump_hex(" |%s|\n", p, xhdr_len);
 263                 p += xhdr_len;
 264                 len -= xhdr_len;
 265         }
 266 }
 267 #else
 268 # define dump_hex(...) ((void)0)
 269 # define dump_tls_record(...) ((void)0)
 270 #endif
 271
 272 void tls_get_random(void *buf, unsigned len)
 273 {
 274         if (len != open_read_close("/dev/urandom", buf, len))
 275                 xfunc_die();
 276 }
 277
 278 //TODO rename this to sha256_hash, and sha256_hash -> sha256_update
 279 static void hash_sha256(uint8_t out[SHA256_OUTSIZE], const void *data, unsigned size)
 280 {
 281         sha256_ctx_t ctx;
 282         sha256_begin(&ctx);
 283         sha256_hash(&ctx, data, size);
 284         sha256_end(&ctx, out);
 285 }
 286
 287 /* Nondestructively see the current hash value */
 288 static void sha256_peek(sha256_ctx_t *ctx, void *buffer)
 289 {
 290         sha256_ctx_t ctx_copy = *ctx;
 291         sha256_end(&ctx_copy, buffer);
 292 }
 293
 294 #if TLS_DEBUG_HASH
 295 static void sha256_hash_dbg(const char *fmt, sha256_ctx_t *ctx, const void *buffer, size_t len)
 296 {
 297         uint8_t h[SHA256_OUTSIZE];
 298
 299         sha256_hash(ctx, buffer, len);
 300         dump_hex(fmt, buffer, len);
 301         dbg(" (%u) ", (int)len);
 302         sha256_peek(ctx, h);
 303         dump_hex("%s\n", h, SHA256_OUTSIZE);
 304 }
 305 #else
 306 # define sha256_hash_dbg(fmt, ctx, buffer, len) \
 307          sha256_hash(ctx, buffer, len)
 308 #endif
 309
 310 // RFC 2104
 311 // HMAC(key, text) based on a hash H (say, sha256) is:
 312 // ipad = [0x36 x INSIZE]
 313 // opad = [0x5c x INSIZE]
 314 // HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text))
 315 //
 316 // H(key XOR opad) and H(key XOR ipad) can be precomputed
 317 // if we often need HMAC hmac with the same key.
 318 //
 319 // text is often given in disjoint pieces.
 320 static void hmac_sha256_precomputed_v(uint8_t out[SHA256_OUTSIZE],
 321                 sha256_ctx_t *hashed_key_xor_ipad,
 322                 sha256_ctx_t *hashed_key_xor_opad,
 323                 va_list va)
 324 {
 325         uint8_t *text;
 326
 327         /* hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
 328         /* hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
 329
 330         /* calculate out = H((key XOR ipad) + text) */
 331         while ((text = va_arg(va, uint8_t*)) != NULL) {
 332                 unsigned text_size = va_arg(va, unsigned);
 333                 sha256_hash(hashed_key_xor_ipad, text, text_size);
 334         }
 335         sha256_end(hashed_key_xor_ipad, out);
 336
 337         /* out = H((key XOR opad) + out) */
 338         sha256_hash(hashed_key_xor_opad, out, SHA256_OUTSIZE);
 339         sha256_end(hashed_key_xor_opad, out);
 340 }
 341
 342 static void hmac_sha256(uint8_t out[SHA256_OUTSIZE], uint8_t *key, unsigned key_size, ...)
 343 {
 344         sha256_ctx_t hashed_key_xor_ipad;
 345         sha256_ctx_t hashed_key_xor_opad;
 346         uint8_t key_xor_ipad[SHA256_INSIZE];
 347         uint8_t key_xor_opad[SHA256_INSIZE];
 348         uint8_t tempkey[SHA256_OUTSIZE];
 349         va_list va;
 350         int i;
 351
 352         va_start(va, key_size);
 353
 354         // "The authentication key can be of any length up to INSIZE, the
 355         // block length of the hash function.  Applications that use keys longer
 356         // than INSIZE bytes will first hash the key using H and then use the
 357         // resultant OUTSIZE byte string as the actual key to HMAC."
 358         if (key_size > SHA256_INSIZE) {
 359                 hash_sha256(tempkey, key, key_size);
 360                 key = tempkey;
 361                 key_size = SHA256_OUTSIZE;
 362         }
 363
 364         for (i = 0; i < key_size; i++) {
 365                 key_xor_ipad[i] = key[i] ^ 0x36;
 366                 key_xor_opad[i] = key[i] ^ 0x5c;
 367         }
 368         for (; i < SHA256_INSIZE; i++) {
 369                 key_xor_ipad[i] = 0x36;
 370                 key_xor_opad[i] = 0x5c;
 371         }
 372         sha256_begin(&hashed_key_xor_ipad);
 373         sha256_hash(&hashed_key_xor_ipad, key_xor_ipad, SHA256_INSIZE);
 374         sha256_begin(&hashed_key_xor_opad);
 375         sha256_hash(&hashed_key_xor_opad, key_xor_opad, SHA256_INSIZE);
 376
 377         hmac_sha256_precomputed_v(out, &hashed_key_xor_ipad, &hashed_key_xor_opad, va);
 378         va_end(va);
 379 }
 380
 381 // RFC 5246:
 382 // 5.  HMAC and the Pseudorandom Function
 383 //...
 384 // In this section, we define one PRF, based on HMAC.  This PRF with the
 385 // SHA-256 hash function is used for all cipher suites defined in this
 386 // document and in TLS documents published prior to this document when
 387 // TLS 1.2 is negotiated.
 388 //...
 389 //    P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
 390 //                           HMAC_hash(secret, A(2) + seed) +
 391 //                           HMAC_hash(secret, A(3) + seed) + ...
 392 // where + indicates concatenation.
 393 // A() is defined as:
 394 //    A(0) = seed
 395 //    A(1) = HMAC_hash(secret, A(0)) = HMAC_hash(secret, seed)
 396 //    A(i) = HMAC_hash(secret, A(i-1))
 397 // P_hash can be iterated as many times as necessary to produce the
 398 // required quantity of data.  For example, if P_SHA256 is being used to
 399 // create 80 bytes of data, it will have to be iterated three times
 400 // (through A(3)), creating 96 bytes of output data; the last 16 bytes
 401 // of the final iteration will then be discarded, leaving 80 bytes of
 402 // output data.
 403 //
 404 // TLS's PRF is created by applying P_hash to the secret as:
 405 //
 406 //    PRF(secret, label, seed) = P_<hash>(secret, label + seed)
 407 //
 408 // The label is an ASCII string.
 409 static void prf_hmac_sha256(
 410                 uint8_t *outbuf, unsigned outbuf_size,
 411                 uint8_t *secret, unsigned secret_size,
 412                 const char *label,
 413                 uint8_t *seed, unsigned seed_size)
 414 {
 415         uint8_t a[SHA256_OUTSIZE];
 416         uint8_t *out_p = outbuf;
 417         unsigned label_size = strlen(label);
 418
 419         /* In P_hash() calculation, "seed" is "label + seed": */
 420 #define SEED   label, label_size, seed, seed_size
 421 #define SECRET secret, secret_size
 422 #define A      a, (int)(sizeof(a))
 423
 424         /* A(1) = HMAC_hash(secret, seed) */
 425         hmac_sha256(a, SECRET, SEED, NULL);
 426 //TODO: convert hmac_sha256 to precomputed
 427
 428         for(;;) {
 429                 /* HMAC_hash(secret, A(1) + seed) */
 430                 if (outbuf_size <= SHA256_OUTSIZE) {
 431                         /* Last, possibly incomplete, block */
 432                         /* (use a[] as temp buffer) */
 433                         hmac_sha256(a, SECRET, A, SEED, NULL);
 434                         memcpy(out_p, a, outbuf_size);
 435                         return;
 436                 }
 437                 /* Not last block. Store directly to result buffer */
 438                 hmac_sha256(out_p, SECRET, A, SEED, NULL);
 439                 out_p += SHA256_OUTSIZE;
 440                 outbuf_size -= SHA256_OUTSIZE;
 441                 /* A(2) = HMAC_hash(secret, A(1)) */
 442                 hmac_sha256(a, SECRET, A, NULL);
 443         }
 444 #undef A
 445 #undef SECRET
 446 #undef SEED
 447 }
 448
 449 static void bad_record_die(tls_state_t *tls, const char *expected, int len)
 450 {
 451         bb_error_msg_and_die("got bad TLS record (len:%d) while expecting %s", len, expected);
 452         if (len > 0) {
 453                 uint8_t *p = tls->inbuf;
 454                 while (len > 0)
 455                         fprintf(stderr, " %02x", *p++);
 456                 fputc('\n', stderr);
 457         }
 458         xfunc_die();
 459 }
 460
 461 static void tls_error_die(tls_state_t *tls)
 462 {
 463         dump_tls_record(tls->inbuf, tls->ofs_to_buffered + tls->buffered_size);
 464         bb_error_msg_and_die("TODO: useful diagnostic about %p", tls);
 465 }
 466
 467 #if 0 //UNUSED
 468 static void tls_free_inbuf(tls_state_t *tls)
 469 {
 470         if (tls->buffered_size == 0) {
 471                 free(tls->inbuf);
 472                 tls->inbuf_size = 0;
 473                 tls->inbuf = NULL;
 474         }
 475 }
 476 #endif
 477
 478 static void tls_free_outbuf(tls_state_t *tls)
 479 {
 480         free(tls->outbuf);
 481         tls->outbuf_size = 0;
 482         tls->outbuf = NULL;
 483 }
 484
 485 static void *tls_get_outbuf(tls_state_t *tls, int len)
 486 {
 487         if (len > MAX_OUTBUF)
 488                 xfunc_die();
 489         if (tls->outbuf_size < len + OUTBUF_PFX + OUTBUF_SFX) {
 490                 tls->outbuf_size = len + OUTBUF_PFX + OUTBUF_SFX;
 491                 tls->outbuf = xrealloc(tls->outbuf, tls->outbuf_size);
 492         }
 493         return tls->outbuf + OUTBUF_PFX;
 494 }
 495
 496 static void xwrite_encrypted(tls_state_t *tls, unsigned size, unsigned type)
 497 {
 498         uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 499         struct record_hdr *xhdr;
 500         uint8_t padding_length;
 501
 502         xhdr = (void*)(buf - RECHDR_LEN);
 503         if (CIPHER_ID != TLS_RSA_WITH_NULL_SHA256)
 504                 xhdr = (void*)(buf - RECHDR_LEN - AES_BLOCKSIZE); /* place for IV */
 505
 506         xhdr->type = type;
 507         xhdr->proto_maj = TLS_MAJ;
 508         xhdr->proto_min = TLS_MIN;
 509         /* fake unencrypted record len for MAC calculation */
 510         xhdr->len16_hi = size >> 8;
 511         xhdr->len16_lo = size & 0xff;
 512
 513         /* Calculate MAC signature */
 514 //TODO: convert hmac_sha256 to precomputed
 515         hmac_sha256(buf + size,
 516                         tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key),
 517                         &tls->write_seq64_be, sizeof(tls->write_seq64_be),
 518                         xhdr, RECHDR_LEN,
 519                         buf, size,
 520                         NULL);
 521         tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
 522
 523         size += SHA256_OUTSIZE;
 524
 525         // RFC 5246
 526         // 6.2.3.1.  Null or Standard Stream Cipher
 527         //
 528         // Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6)
 529         // convert TLSCompressed.fragment structures to and from stream
 530         // TLSCiphertext.fragment structures.
 531         //
 532         //    stream-ciphered struct {
 533         //        opaque content[TLSCompressed.length];
 534         //        opaque MAC[SecurityParameters.mac_length];
 535         //    } GenericStreamCipher;
 536         //
 537         // The MAC is generated as:
 538         //    MAC(MAC_write_key, seq_num +
 539         //                          TLSCompressed.type +
 540         //                          TLSCompressed.version +
 541         //                          TLSCompressed.length +
 542         //                          TLSCompressed.fragment);
 543         // where "+" denotes concatenation.
 544         // seq_num
 545         //    The sequence number for this record.
 546         // MAC
 547         //    The MAC algorithm specified by SecurityParameters.mac_algorithm.
 548         //
 549         // Note that the MAC is computed before encryption.  The stream cipher
 550         // encrypts the entire block, including the MAC.
 551         //...
 552         // Appendix C.  Cipher Suite Definitions
 553         //...
 554         // MAC       Algorithm    mac_length  mac_key_length
 555         // --------  -----------  ----------  --------------
 556         // SHA       HMAC-SHA1       20            20
 557         // SHA256    HMAC-SHA256     32            32
 558         if (CIPHER_ID == TLS_RSA_WITH_NULL_SHA256) {
 559                 /* No encryption, only signing */
 560                 xhdr->len16_hi = size >> 8;
 561                 xhdr->len16_lo = size & 0xff;
 562                 dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 563                 xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 564                 dbg("wrote %u bytes (NULL crypt, SHA256 hash)\n", size);
 565                 return;
 566         }
 567
 568         // 6.2.3.2.  CBC Block Cipher
 569         // For block ciphers (such as 3DES or AES), the encryption and MAC
 570         // functions convert TLSCompressed.fragment structures to and from block
 571         // TLSCiphertext.fragment structures.
 572         //    struct {
 573         //        opaque IV[SecurityParameters.record_iv_length];
 574         //        block-ciphered struct {
 575         //            opaque content[TLSCompressed.length];
 576         //            opaque MAC[SecurityParameters.mac_length];
 577         //            uint8 padding[GenericBlockCipher.padding_length];
 578         //            uint8 padding_length;
 579         //        };
 580         //    } GenericBlockCipher;
 581         //...
 582         // IV
 583         //    The Initialization Vector (IV) SHOULD be chosen at random, and
 584         //    MUST be unpredictable.  Note that in versions of TLS prior to 1.1,
 585         //    there was no IV field (...).  For block ciphers, the IV length is
 586         //    of length SecurityParameters.record_iv_length, which is equal to the
 587         //    SecurityParameters.block_size.
 588         // padding
 589         //    Padding that is added to force the length of the plaintext to be
 590         //    an integral multiple of the block cipher's block length.
 591         // padding_length
 592         //    The padding length MUST be such that the total size of the
 593         //    GenericBlockCipher structure is a multiple of the cipher's block
 594         //    length.  Legal values range from zero to 255, inclusive.
 595         //...
 596         // Appendix C.  Cipher Suite Definitions
 597         //...
 598         //                         Key      IV   Block
 599         // Cipher        Type    Material  Size  Size
 600         // ------------  ------  --------  ----  -----
 601         // AES_128_CBC   Block      16      16     16
 602         // AES_256_CBC   Block      32      16     16
 603
 604         /* Fill IV and padding in outbuf */
 605         tls_get_random(buf - AES_BLOCKSIZE, AES_BLOCKSIZE); /* IV */
 606         dbg("before crypt: 5 hdr + %u data + %u hash bytes\n", size, SHA256_OUTSIZE);
 607         // RFC is talking nonsense:
 608         //    "Padding that is added to force the length of the plaintext to be
 609         //    an integral multiple of the block cipher's block length."
 610         // WRONG. _padding+padding_length_, not just _padding_,
 611         // pads the data.
 612         // IOW: padding_length is the last byte of padding[] array,
 613         // contrary to what RFC depicts.
 614         //
 615         // What actually happens is that there is always padding.
 616         // If you need one byte to reach BLOCKSIZE, this byte is 0x00.
 617         // If you need two bytes, they are both 0x01.
 618         // If you need three, they are 0x02,0x02,0x02. And so on.
 619         // If you need no bytes to reach BLOCKSIZE, you have to pad a full
 620         // BLOCKSIZE with bytes of value (BLOCKSIZE-1).
 621         // It's ok to have more than minimum padding, but we do minimum.
 622         padding_length = (~size) & (AES_BLOCKSIZE - 1);
 623         do {
 624                 buf[size++] = padding_length; /* padding */
 625         } while ((size & (AES_BLOCKSIZE - 1)) != 0);
 626
 627         /* Encrypt content+MAC+padding in place */
 628         {
 629                 psCipherContext_t ctx;
 630                 psAesInit(&ctx, buf - AES_BLOCKSIZE, /* IV */
 631                         tls->client_write_key, sizeof(tls->client_write_key)
 632                 );
 633                 psAesEncrypt(&ctx,
 634                         buf, /* plaintext */
 635                         buf, /* ciphertext */
 636                         size
 637                 );
 638         }
 639
 640         /* Write out */
 641         dbg("writing 5 + %u IV + %u encrypted bytes, padding_length:0x%02x\n",
 642                         AES_BLOCKSIZE, size, padding_length);
 643         size += AES_BLOCKSIZE;     /* + IV */
 644         xhdr->len16_hi = size >> 8;
 645         xhdr->len16_lo = size & 0xff;
 646         dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 647         xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 648         dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 649 }
 650
 651 static void xwrite_and_update_handshake_hash(tls_state_t *tls, unsigned size)
 652 {
 653         if (!tls->encrypt_on_write) {
 654                 uint8_t *buf = tls->outbuf + OUTBUF_PFX;
 655                 struct record_hdr *xhdr = (void*)(buf - RECHDR_LEN);
 656
 657                 xhdr->type = RECORD_TYPE_HANDSHAKE;
 658                 xhdr->proto_maj = TLS_MAJ;
 659                 xhdr->proto_min = TLS_MIN;
 660                 xhdr->len16_hi = size >> 8;
 661                 xhdr->len16_lo = size & 0xff;
 662                 dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size);
 663                 xwrite(tls->ofd, xhdr, RECHDR_LEN + size);
 664                 dbg("wrote %u bytes\n", (int)RECHDR_LEN + size);
 665                 /* Handshake hash does not include record headers */
 666                 sha256_hash_dbg(">> sha256:%s", &tls->hsd->handshake_sha256_ctx, buf, size);
 667                 return;
 668         }
 669         xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
 670 }
 671
 672 static int tls_has_buffered_record(tls_state_t *tls)
 673 {
 674         int buffered = tls->buffered_size;
 675         struct record_hdr *xhdr;
 676         int rec_size;
 677
 678         if (buffered < RECHDR_LEN)
 679                 return 0;
 680         xhdr = (void*)(tls->inbuf + tls->ofs_to_buffered);
 681         rec_size = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
 682         if (buffered < rec_size)
 683                 return 0;
 684         return rec_size;
 685 }
 686
 687 static const char *alert_text(int code)
 688 {
 689         switch (code) {
 690         case 20:  return "bad MAC";
 691         case 50:  return "decode error";
 692         case 51:  return "decrypt error";
 693         case 40:  return "handshake failure";
 694         case 112: return "unrecognized name";
 695         }
 696         return itoa(code);
 697 }
 698
 699 static int tls_xread_record(tls_state_t *tls)
 700 {
 701         struct record_hdr *xhdr;
 702         int sz;
 703         int total;
 704         int target;
 705
 706  again:
 707         dbg("ofs_to_buffered:%u buffered_size:%u\n", tls->ofs_to_buffered, tls->buffered_size);
 708         total = tls->buffered_size;
 709         if (total != 0) {
 710                 memmove(tls->inbuf, tls->inbuf + tls->ofs_to_buffered, total);
 711                 //dbg("<< remaining at %d [%d] ", tls->ofs_to_buffered, total);
 712                 //dump_raw_in("<< %s\n", tls->inbuf, total);
 713         }
 714         errno = 0;
 715         target = MAX_INBUF;
 716         for (;;) {
 717                 int rem;
 718
 719                 if (total >= RECHDR_LEN && target == MAX_INBUF) {
 720                         xhdr = (void*)tls->inbuf;
 721                         target = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo);
 722                         if (target > MAX_INBUF) {
 723                                 /* malformed input (too long): yell and die */
 724                                 tls->buffered_size = 0;
 725                                 tls->ofs_to_buffered = total;
 726                                 tls_error_die(tls);
 727                         }
 728                         /* can also check type/proto_maj/proto_min here */
 729                         dbg("xhdr type:%d ver:%d.%d len:%d\n",
 730                                 xhdr->type, xhdr->proto_maj, xhdr->proto_min,
 731                                 0x100 * xhdr->len16_hi + xhdr->len16_lo
 732                         );
 733                 }
 734                 /* if total >= target, we have a full packet (and possibly more)... */
 735                 if (total - target >= 0)
 736                         break;
 737                 /* input buffer is grown only as needed */
 738                 rem = tls->inbuf_size - total;
 739                 if (rem == 0) {
 740                         tls->inbuf_size += MAX_INBUF / 8;
 741                         if (tls->inbuf_size > MAX_INBUF)
 742                                 tls->inbuf_size = MAX_INBUF;
 743                         dbg("inbuf_size:%d\n", tls->inbuf_size);
 744                         rem = tls->inbuf_size - total;
 745                         tls->inbuf = xrealloc(tls->inbuf, tls->inbuf_size);
 746                 }
 747                 sz = safe_read(tls->ifd, tls->inbuf + total, rem);
 748                 if (sz <= 0) {
 749                         if (sz == 0 && total == 0) {
 750                                 /* "Abrupt" EOF, no TLS shutdown (seen from kernel.org) */
 751                                 dbg("EOF (without TLS shutdown) from peer\n");
 752                                 tls->buffered_size = 0;
 753                                 goto end;
 754                         }
 755                         bb_perror_msg_and_die("short read, have only %d", total);
 756                 }
 757                 dump_raw_in("<< %s\n", tls->inbuf + total, sz);
 758                 total += sz;
 759         }
 760         tls->buffered_size = total - target;
 761         tls->ofs_to_buffered = target;
 762         //dbg("<< stashing at %d [%d] ", tls->ofs_to_buffered, tls->buffered_size);
 763         //dump_hex("<< %s\n", tls->inbuf + tls->ofs_to_buffered, tls->buffered_size);
 764
 765         sz = target - RECHDR_LEN;
 766
 767         /* Needs to be decrypted? */
 768         if (tls->min_encrypted_len_on_read > SHA256_OUTSIZE) {
 769                 psCipherContext_t ctx;
 770                 uint8_t *p = tls->inbuf + RECHDR_LEN;
 771                 int padding_len;
 772
 773                 if (sz & (AES_BLOCKSIZE-1)
 774                  || sz < tls->min_encrypted_len_on_read
 775                 ) {
 776                         bb_error_msg_and_die("bad encrypted len:%u", sz);
 777                 }
 778                 /* Decrypt content+MAC+padding, moving it over IV in the process */
 779                 psAesInit(&ctx, p, /* IV */
 780                         tls->server_write_key, sizeof(tls->server_write_key)
 781                 );
 782                 sz -= AES_BLOCKSIZE; /* we will overwrite IV now */
 783                 psAesDecrypt(&ctx,
 784                         p + AES_BLOCKSIZE, /* ciphertext */
 785                         p,                 /* plaintext */
 786                         sz
 787                 );
 788                 padding_len = p[sz - 1];
 789                 dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[0], padding_len);
 790                 padding_len++;
 791                 sz -= SHA256_OUTSIZE + padding_len; /* drop MAC and padding */
 792                 //if (sz < 0)
 793                 //      bb_error_msg_and_die("bad padding size:%u", padding_len);
 794         } else {
 795                 /* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
 796                 /* else: no encryption yet on input, subtract zero = NOP */
 797                 sz -= tls->min_encrypted_len_on_read;
 798         }
 799         if (sz < 0)
 800                 bb_error_msg_and_die("encrypted data too short");
 801
 802         //dump_hex("<< %s\n", tls->inbuf, RECHDR_LEN + sz);
 803
 804         xhdr = (void*)tls->inbuf;
 805         if (xhdr->type == RECORD_TYPE_ALERT && sz >= 2) {
 806                 uint8_t *p = tls->inbuf + RECHDR_LEN;
 807                 dbg("ALERT size:%d level:%d description:%d\n", sz, p[0], p[1]);
 808                 if (p[0] == 2) { /* fatal */
 809                         bb_error_msg_and_die("TLS %s from peer (alert code %d): %s",
 810                                 "error",
 811                                 p[1], alert_text(p[1])
 812                         );
 813                 }
 814                 if (p[0] == 1) { /* warning */
 815                         if (p[1] == 0) { /* "close_notify" warning: it's EOF */
 816                                 dbg("EOF (TLS encoded) from peer\n");
 817                                 sz = 0;
 818                                 goto end;
 819                         }
 820 //This possibly needs to be cached and shown only if
 821 //a fatal alert follows
 822 //                      bb_error_msg("TLS %s from peer (alert code %d): %s",
 823 //                              "warning",
 824 //                              p[1], alert_text(p[1])
 825 //                      );
 826                         /* discard it, get next record */
 827                         goto again;
 828                 }
 829                 /* p[0] not 1 or 2: not defined in protocol */
 830                 sz = 0;
 831                 goto end;
 832         }
 833
 834         /* RFC 5246 is not saying it explicitly, but sha256 hash
 835          * in our FINISHED record must include data of incoming packets too!
 836          */
 837         if (tls->inbuf[0] == RECORD_TYPE_HANDSHAKE) {
 838                 sha256_hash_dbg("<< sha256:%s", &tls->hsd->handshake_sha256_ctx, tls->inbuf + RECHDR_LEN, sz);
 839         }
 840  end:
 841         dbg("got block len:%u\n", sz);
 842         return sz;
 843 }
 844
 845 /*
 846  * DER parsing routines
 847  */
 848 static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end)
 849 {
 850         unsigned len, len1;
 851
 852         if (end - der < 2)
 853                 xfunc_die();
 854 //      if ((der[0] & 0x1f) == 0x1f) /* not single-byte item code? */
 855 //              xfunc_die();
 856
 857         len = der[1]; /* maybe it's short len */
 858         if (len >= 0x80) {
 859                 /* no, it's long */
 860
 861                 if (len == 0x80 || end - der < (int)(len - 0x7e)) {
 862                         /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */
 863                         /* need 3 or 4 bytes for 81, 82 */
 864                         xfunc_die();
 865                 }
 866
 867                 len1 = der[2]; /* if (len == 0x81) it's "ii 81 xx", fetch xx */
 868                 if (len > 0x82) {
 869                         /* >0x82 is "3+ bytes of len", should not happen realistically */
 870                         xfunc_die();
 871                 }
 872                 if (len == 0x82) { /* it's "ii 82 xx yy" */
 873                         len1 = 0x100*len1 + der[3];
 874                         der += 1; /* skip [yy] */
 875                 }
 876                 der += 1; /* skip [xx] */
 877                 len = len1;
 878 //              if (len < 0x80)
 879 //                      xfunc_die(); /* invalid DER: must use short len if can */
 880         }
 881         der += 2; /* skip [code]+[1byte] */
 882
 883         if (end - der < (int)len)
 884                 xfunc_die();
 885         *bodyp = der;
 886
 887         return len;
 888 }
 889
 890 static uint8_t *enter_der_item(uint8_t *der, uint8_t **endp)
 891 {
 892         uint8_t *new_der;
 893         unsigned len = get_der_len(&new_der, der, *endp);
 894         dbg_der("entered der @%p:0x%02x len:%u inner_byte @%p:0x%02x\n", der, der[0], len, new_der, new_der[0]);
 895         /* Move "end" position to cover only this item */
 896         *endp = new_der + len;
 897         return new_der;
 898 }
 899
 900 static uint8_t *skip_der_item(uint8_t *der, uint8_t *end)
 901 {
 902         uint8_t *new_der;
 903         unsigned len = get_der_len(&new_der, der, end);
 904         /* Skip body */
 905         new_der += len;
 906         dbg_der("skipped der 0x%02x, next byte 0x%02x\n", der[0], new_der[0]);
 907         return new_der;
 908 }
 909
 910 static void der_binary_to_pstm(pstm_int *pstm_n, uint8_t *der, uint8_t *end)
 911 {
 912         uint8_t *bin_ptr;
 913         unsigned len = get_der_len(&bin_ptr, der, end);
 914
 915         dbg_der("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]);
 916         pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len);
 917         pstm_read_unsigned_bin(pstm_n, bin_ptr, len);
 918         //return bin + len;
 919 }
 920
 921 static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len)
 922 {
 923 /* Certificate is a DER-encoded data structure. Each DER element has a length,
 924  * which makes it easy to skip over large compound elements of any complexity
 925  * without parsing them. Example: partial decode of kernel.org certificate:
 926  *  SEQ 0x05ac/1452 bytes (Certificate): 308205ac
 927  *    SEQ 0x0494/1172 bytes (tbsCertificate): 30820494
 928  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0] 3 bytes: a003
 929  *        INTEGER (version): 0201 02
 930  *      INTEGER 0x11 bytes (serialNumber): 0211 00 9f85bf664b0cddafca508679501b2be4
 931  *      //^^^^^^note: matrixSSL also allows [ASN_CONTEXT_SPECIFIC | ASN_PRIMITIVE | 2] = 0x82 type
 932  *      SEQ 0x0d bytes (signatureAlgo): 300d
 933  *        OID 9 bytes: 0609 2a864886f70d01010b (OID_SHA256_RSA_SIG 42.134.72.134.247.13.1.1.11)
 934  *        NULL: 0500
 935  *      SEQ 0x5f bytes (issuer): 305f
 936  *        SET 11 bytes: 310b
 937  *          SEQ 9 bytes: 3009
 938  *            OID 3 bytes: 0603 550406
 939  *            Printable string "FR": 1302 4652
 940  *        SET 14 bytes: 310e
 941  *          SEQ 12 bytes: 300c
 942  *            OID 3 bytes: 0603 550408
 943  *            Printable string "Paris": 1305 5061726973
 944  *        SET 14 bytes: 310e
 945  *          SEQ 12 bytes: 300c
 946  *            OID 3 bytes: 0603 550407
 947  *            Printable string "Paris": 1305 5061726973
 948  *        SET 14 bytes: 310e
 949  *          SEQ 12 bytes: 300c
 950  *            OID 3 bytes: 0603 55040a
 951  *            Printable string "Gandi": 1305 47616e6469
 952  *        SET 32 bytes: 3120
 953  *          SEQ 30 bytes: 301e
 954  *            OID 3 bytes: 0603 550403
 955  *            Printable string "Gandi Standard SSL CA 2": 1317 47616e6469205374616e646172642053534c2043412032
 956  *      SEQ 30 bytes (validity): 301e
 957  *        TIME "161011000000Z": 170d 3136313031313030303030305a
 958  *        TIME "191011235959Z": 170d 3139313031313233353935395a
 959  *      SEQ 0x5b/91 bytes (subject): 305b //I did not decode this
 960  *          3121301f060355040b1318446f6d61696e20436f
 961  *          6e74726f6c2056616c6964617465643121301f06
 962  *          0355040b1318506f73697469766553534c204d75
 963  *          6c74692d446f6d61696e31133011060355040313
 964  *          0a6b65726e656c2e6f7267
 965  *      SEQ 0x01a2/418 bytes (subjectPublicKeyInfo): 308201a2
 966  *        SEQ 13 bytes (algorithm): 300d
 967  *          OID 9 bytes: 0609 2a864886f70d010101 (OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1)
 968  *          NULL: 0500
 969  *        BITSTRING 0x018f/399 bytes (publicKey): 0382018f
 970  *          ????: 00
 971  *          //after the zero byte, it appears key itself uses DER encoding:
 972  *          SEQ 0x018a/394 bytes: 3082018a
 973  *            INTEGER 0x0181/385 bytes (modulus): 02820181
 974  *                  00b1ab2fc727a3bef76780c9349bf3
 975  *                  ...24 more blocks of 15 bytes each...
 976  *                  90e895291c6bc8693b65
 977  *            INTEGER 3 bytes (exponent): 0203 010001
 978  *      [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0x3] 0x01e5 bytes (X509v3 extensions): a38201e5
 979  *        SEQ 0x01e1 bytes: 308201e1
 980  *        ...
 981  * Certificate is a sequence of three elements:
 982  *      tbsCertificate (SEQ)
 983  *      signatureAlgorithm (AlgorithmIdentifier)
 984  *      signatureValue (BIT STRING)
 985  *
 986  * In turn, tbsCertificate is a sequence of:
 987  *      version
 988  *      serialNumber
 989  *      signatureAlgo (AlgorithmIdentifier)
 990  *      issuer (Name, has complex structure)
 991  *      validity (Validity, SEQ of two Times)
 992  *      subject (Name)
 993  *      subjectPublicKeyInfo (SEQ)
 994  *      ...
 995  *
 996  * subjectPublicKeyInfo is a sequence of:
 997  *      algorithm (AlgorithmIdentifier)
 998  *      publicKey (BIT STRING)
 999  *
1000  * We need Certificate.tbsCertificate.subjectPublicKeyInfo.publicKey
1001  */
1002         uint8_t *end = der + len;
1003
1004         /* enter "Certificate" item: [der, end) will be only Cert */
1005         der = enter_der_item(der, &end);
1006
1007         /* enter "tbsCertificate" item: [der, end) will be only tbsCert */
1008         der = enter_der_item(der, &end);
1009
1010         /* skip up to subjectPublicKeyInfo */
1011         der = skip_der_item(der, end); /* version */
1012         der = skip_der_item(der, end); /* serialNumber */
1013         der = skip_der_item(der, end); /* signatureAlgo */
1014         der = skip_der_item(der, end); /* issuer */
1015         der = skip_der_item(der, end); /* validity */
1016         der = skip_der_item(der, end); /* subject */
1017
1018         /* enter subjectPublicKeyInfo */
1019         der = enter_der_item(der, &end);
1020         { /* check subjectPublicKeyInfo.algorithm */
1021                 static const uint8_t expected[] = {
1022                         0x30,0x0d, // SEQ 13 bytes
1023                         0x06,0x09, 0x2a,0x86,0x48,0x86,0xf7,0x0d,0x01,0x01,0x01, // OID RSA_KEY_ALG 42.134.72.134.247.13.1.1.1
1024                         //0x05,0x00, // NULL
1025                 };
1026                 if (memcmp(der, expected, sizeof(expected)) != 0)
1027                         bb_error_msg_and_die("not RSA key");
1028         }
1029         /* skip subjectPublicKeyInfo.algorithm */
1030         der = skip_der_item(der, end);
1031         /* enter subjectPublicKeyInfo.publicKey */
1032 //      die_if_not_this_der_type(der, end, 0x03); /* must be BITSTRING */
1033         der = enter_der_item(der, &end);
1034
1035         /* parse RSA key: */
1036 //based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note
1037         dbg("key bytes:%u, first:0x%02x\n", (int)(end - der), der[0]);
1038         if (end - der < 14) xfunc_die();
1039         /* example format:
1040          * ignore bits: 00
1041          * SEQ 0x018a/394 bytes: 3082018a
1042          *   INTEGER 0x0181/385 bytes (modulus): 02820181 XX...XXX
1043          *   INTEGER 3 bytes (exponent): 0203 010001
1044          */
1045         if (*der != 0) /* "ignore bits", should be 0 */
1046                 xfunc_die();
1047         der++;
1048         der = enter_der_item(der, &end); /* enter SEQ */
1049         /* memset(tls->hsd->server_rsa_pub_key, 0, sizeof(tls->hsd->server_rsa_pub_key)); - already is */
1050         der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.N, der, end); /* modulus */
1051         der = skip_der_item(der, end);
1052         der_binary_to_pstm(&tls->hsd->server_rsa_pub_key.e, der, end); /* exponent */
1053         tls->hsd->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->hsd->server_rsa_pub_key.N);
1054         dbg("server_rsa_pub_key.size:%d\n", tls->hsd->server_rsa_pub_key.size);
1055 }
1056
1057 /*
1058  * TLS Handshake routines
1059  */
1060 static int tls_xread_handshake_block(tls_state_t *tls, int min_len)
1061 {
1062         struct record_hdr *xhdr;
1063         int len = tls_xread_record(tls);
1064
1065         xhdr = (void*)tls->inbuf;
1066         if (len < min_len
1067          || xhdr->type != RECORD_TYPE_HANDSHAKE
1068          || xhdr->proto_maj != TLS_MAJ
1069          || xhdr->proto_min != TLS_MIN
1070         ) {
1071                 bad_record_die(tls, "handshake record", len);
1072         }
1073         dbg("got HANDSHAKE\n");
1074         return len;
1075 }
1076
1077 static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, unsigned len)
1078 {
1079         struct handshake_hdr {
1080                 uint8_t type;
1081                 uint8_t len24_hi, len24_mid, len24_lo;
1082         } *h = buf;
1083
1084         len -= 4;
1085         h->type = type;
1086         h->len24_hi  = len >> 16;
1087         h->len24_mid = len >> 8;
1088         h->len24_lo  = len & 0xff;
1089 }
1090
1091 static void send_client_hello(tls_state_t *tls, const char *sni)
1092 {
1093         struct client_hello {
1094                 uint8_t type;
1095                 uint8_t len24_hi, len24_mid, len24_lo;
1096                 uint8_t proto_maj, proto_min;
1097                 uint8_t rand32[32];
1098                 uint8_t session_id_len;
1099                 /* uint8_t session_id[]; */
1100                 uint8_t cipherid_len16_hi, cipherid_len16_lo;
1101                 uint8_t cipherid[2 * 2]; /* actually variable */
1102                 uint8_t comprtypes_len;
1103                 uint8_t comprtypes[1]; /* actually variable */
1104                 /* Extensions (SNI shown):
1105                  * hi,lo // len of all extensions
1106                  *   00,00 // extension_type: "Server Name"
1107                  *   00,0e // list len (there can be more than one SNI)
1108                  *     00,0c // len of 1st Server Name Indication
1109                  *       00    // name type: host_name
1110                  *       00,09   // name len
1111                  *       "localhost" // name
1112                  */
1113 // GNU Wget 1.18 to cdn.kernel.org sends these extensions:
1114 // 0055
1115 //   0005 0005 0100000000 - status_request
1116 //   0000 0013 0011 00 000e 63646e 2e 6b65726e656c 2e 6f7267 - server_name
1117 //   ff01 0001 00 - renegotiation_info
1118 //   0023 0000 - session_ticket
1119 //   000a 0008 0006001700180019 - supported_groups
1120 //   000b 0002 0100 - ec_point_formats
1121 //   000d 0016 00140401040305010503060106030301030302010203 - signature_algorithms
1122         };
1123         struct client_hello *record;
1124         int len;
1125         int sni_len = sni ? strnlen(sni, 127) : 0;
1126
1127         len = sizeof(*record);
1128         if (sni_len)
1129                 len += 11 + strlen(sni);
1130         record = tls_get_outbuf(tls, len);
1131         memset(record, 0, len);
1132
1133         fill_handshake_record_hdr(record, HANDSHAKE_CLIENT_HELLO, len);
1134         record->proto_maj = TLS_MAJ;    /* the "requested" version of the protocol, */
1135         record->proto_min = TLS_MIN;    /* can be higher than one in record headers */
1136         tls_get_random(record->rand32, sizeof(record->rand32));
1137         if (TLS_DEBUG_FIXED_SECRETS)
1138                 memset(record->rand32, 0x11, sizeof(record->rand32));
1139         memcpy(tls->hsd->client_and_server_rand32, record->rand32, sizeof(record->rand32));
1140         /* record->session_id_len = 0; - already is */
1141
1142         /* record->cipherid_len16_hi = 0; */
1143         record->cipherid_len16_lo = 2 * 2;
1144         if ((CIPHER_ID >> 8) != 0)
1145                 record->cipherid[0] = CIPHER_ID >> 8;
1146         record->cipherid[1] = CIPHER_ID & 0xff;
1147         /* RFC 5746 Renegotiation Indication Extension - some servers will refuse to work with us otherwise */
1148         /*record->cipherid[2] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV >> 8; - zero */
1149         record->cipherid[3] = TLS_EMPTY_RENEGOTIATION_INFO_SCSV & 0xff;
1150
1151         record->comprtypes_len = 1;
1152         /* record->comprtypes[0] = 0; */
1153
1154         if (sni_len) {
1155                 uint8_t *p = (void*)(record + 1);
1156                 //p[0] = 0;         //
1157                 p[1] = sni_len + 9; //ext_len
1158                 //p[2] = 0;             //
1159                 //p[3] = 0;             //extension_type
1160                 //p[4] = 0;         //
1161                 p[5] = sni_len + 5; //list len
1162                 //p[6] = 0;             //
1163                 p[7] = sni_len + 3;     //len of 1st SNI
1164                 //p[8] = 0;         //name type
1165                 //p[9] = 0;             //
1166                 p[10] = sni_len;        //name len
1167                 memcpy(&p[11], sni, sni_len);
1168         }
1169
1170         dbg(">> CLIENT_HELLO\n");
1171         xwrite_and_update_handshake_hash(tls, len);
1172 }
1173
1174 static void get_server_hello(tls_state_t *tls)
1175 {
1176         struct server_hello {
1177                 struct record_hdr xhdr;
1178                 uint8_t type;
1179                 uint8_t len24_hi, len24_mid, len24_lo;
1180                 uint8_t proto_maj, proto_min;
1181                 uint8_t rand32[32]; /* first 4 bytes are unix time in BE format */
1182                 uint8_t session_id_len;
1183                 uint8_t session_id[32];
1184                 uint8_t cipherid_hi, cipherid_lo;
1185                 uint8_t comprtype;
1186                 /* extensions may follow, but only those which client offered in its Hello */
1187         };
1188
1189         struct server_hello *hp;
1190         uint8_t *cipherid;
1191         int len;
1192
1193         len = tls_xread_handshake_block(tls, 74);
1194
1195         hp = (void*)tls->inbuf;
1196         // 74 bytes:
1197         // 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|
1198         //SvHl len=70 maj.min unixtime^^^ 28randbytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^ slen sid32bytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cipSel comprSel
1199         if (hp->type != HANDSHAKE_SERVER_HELLO
1200          || hp->len24_hi  != 0
1201          || hp->len24_mid != 0
1202          /* hp->len24_lo checked later */
1203          || hp->proto_maj != TLS_MAJ
1204          || hp->proto_min != TLS_MIN
1205         ) {
1206                 bad_record_die(tls, "'server hello'", len);
1207         }
1208
1209         cipherid = &hp->cipherid_hi;
1210         if (hp->session_id_len != 32) {
1211                 if (hp->session_id_len != 0)
1212                         tls_error_die(tls);
1213
1214                 // session_id_len == 0: no session id
1215                 // "The server
1216                 // may return an empty session_id to indicate that the session will
1217                 // not be cached and therefore cannot be resumed."
1218                 cipherid -= 32;
1219                 hp->len24_lo += 32; /* what len would be if session id would be present */
1220         }
1221
1222         if (hp->len24_lo < 70
1223          || cipherid[0]  != (CIPHER_ID >> 8)
1224          || cipherid[1]  != (CIPHER_ID & 0xff)
1225          || cipherid[2]  != 0 /* comprtype */
1226         ) {
1227                 tls_error_die(tls);
1228         }
1229
1230         dbg("<< SERVER_HELLO\n");
1231         memcpy(tls->hsd->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32));
1232 }
1233
1234 static void get_server_cert(tls_state_t *tls)
1235 {
1236         struct record_hdr *xhdr;
1237         uint8_t *certbuf;
1238         int len, len1;
1239
1240         len = tls_xread_handshake_block(tls, 10);
1241
1242         xhdr = (void*)tls->inbuf;
1243         certbuf = (void*)(xhdr + 1);
1244         if (certbuf[0] != HANDSHAKE_CERTIFICATE)
1245                 tls_error_die(tls);
1246         dbg("<< CERTIFICATE\n");
1247         // 4392 bytes:
1248         // 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...
1249         //Cert len=4388 ChainLen CertLen^ DER encoded X509 starts here. openssl x509 -in FILE -inform DER -noout -text
1250         len1 = get24be(certbuf + 1);
1251         if (len1 > len - 4) tls_error_die(tls);
1252         len = len1;
1253         len1 = get24be(certbuf + 4);
1254         if (len1 > len - 3) tls_error_die(tls);
1255         len = len1;
1256         len1 = get24be(certbuf + 7);
1257         if (len1 > len - 3) tls_error_die(tls);
1258         len = len1;
1259
1260         if (len)
1261                 find_key_in_der_cert(tls, certbuf + 10, len);
1262 }
1263
1264 static void send_client_key_exchange(tls_state_t *tls)
1265 {
1266         struct client_key_exchange {
1267                 uint8_t type;
1268                 uint8_t len24_hi, len24_mid, len24_lo;
1269                 /* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */
1270                 uint8_t keylen16_hi, keylen16_lo;
1271                 uint8_t key[4 * 1024]; // size??
1272         };
1273 //FIXME: better size estimate
1274         struct client_key_exchange *record = tls_get_outbuf(tls, sizeof(*record));
1275         uint8_t rsa_premaster[RSA_PREMASTER_SIZE];
1276         int len;
1277
1278         tls_get_random(rsa_premaster, sizeof(rsa_premaster));
1279         if (TLS_DEBUG_FIXED_SECRETS)
1280                 memset(rsa_premaster, 0x44, sizeof(rsa_premaster));
1281         // RFC 5246
1282         // "Note: The version number in the PreMasterSecret is the version
1283         // offered by the client in the ClientHello.client_version, not the
1284         // version negotiated for the connection."
1285         rsa_premaster[0] = TLS_MAJ;
1286         rsa_premaster[1] = TLS_MIN;
1287         len = psRsaEncryptPub(/*pool:*/ NULL,
1288                 /* psRsaKey_t* */ &tls->hsd->server_rsa_pub_key,
1289                 rsa_premaster, /*inlen:*/ sizeof(rsa_premaster),
1290                 record->key, sizeof(record->key),
1291                 data_param_ignored
1292         );
1293         record->keylen16_hi = len >> 8;
1294         record->keylen16_lo = len & 0xff;
1295         len += 2;
1296         record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
1297         record->len24_hi  = 0;
1298         record->len24_mid = len >> 8;
1299         record->len24_lo  = len & 0xff;
1300         len += 4;
1301
1302         dbg(">> CLIENT_KEY_EXCHANGE\n");
1303         xwrite_and_update_handshake_hash(tls, len);
1304
1305         // RFC 5246
1306         // For all key exchange methods, the same algorithm is used to convert
1307         // the pre_master_secret into the master_secret.  The pre_master_secret
1308         // should be deleted from memory once the master_secret has been
1309         // computed.
1310         //      master_secret = PRF(pre_master_secret, "master secret",
1311         //                          ClientHello.random + ServerHello.random)
1312         //                          [0..47];
1313         // The master secret is always exactly 48 bytes in length.  The length
1314         // of the premaster secret will vary depending on key exchange method.
1315         prf_hmac_sha256(
1316                 tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1317                 rsa_premaster, sizeof(rsa_premaster),
1318                 "master secret",
1319                 tls->hsd->client_and_server_rand32, sizeof(tls->hsd->client_and_server_rand32)
1320         );
1321         dump_hex("master secret:%s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
1322
1323         // RFC 5246
1324         // 6.3.  Key Calculation
1325         //
1326         // The Record Protocol requires an algorithm to generate keys required
1327         // by the current connection state (see Appendix A.6) from the security
1328         // parameters provided by the handshake protocol.
1329         //
1330         // The master secret is expanded into a sequence of secure bytes, which
1331         // is then split to a client write MAC key, a server write MAC key, a
1332         // client write encryption key, and a server write encryption key.  Each
1333         // of these is generated from the byte sequence in that order.  Unused
1334         // values are empty.  Some AEAD ciphers may additionally require a
1335         // client write IV and a server write IV (see Section 6.2.3.3).
1336         //
1337         // When keys and MAC keys are generated, the master secret is used as an
1338         // entropy source.
1339         //
1340         // To generate the key material, compute
1341         //
1342         //    key_block = PRF(SecurityParameters.master_secret,
1343         //                    "key expansion",
1344         //                    SecurityParameters.server_random +
1345         //                    SecurityParameters.client_random);
1346         //
1347         // until enough output has been generated.  Then, the key_block is
1348         // partitioned as follows:
1349         //
1350         //    client_write_MAC_key[SecurityParameters.mac_key_length]
1351         //    server_write_MAC_key[SecurityParameters.mac_key_length]
1352         //    client_write_key[SecurityParameters.enc_key_length]
1353         //    server_write_key[SecurityParameters.enc_key_length]
1354         //    client_write_IV[SecurityParameters.fixed_iv_length]
1355         //    server_write_IV[SecurityParameters.fixed_iv_length]
1356         {
1357                 uint8_t tmp64[64];
1358
1359                 /* make "server_rand32 + client_rand32" */
1360                 memcpy(&tmp64[0] , &tls->hsd->client_and_server_rand32[32], 32);
1361                 memcpy(&tmp64[32], &tls->hsd->client_and_server_rand32[0] , 32);
1362
1363                 prf_hmac_sha256(
1364                         tls->client_write_MAC_key, 2 * (SHA256_OUTSIZE + AES256_KEYSIZE),
1365                         // also fills:
1366                         // server_write_MAC_key[SHA256_OUTSIZE]
1367                         // client_write_key[AES256_KEYSIZE]
1368                         // server_write_key[AES256_KEYSIZE]
1369                         tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1370                         "key expansion",
1371                         tmp64, 64
1372                 );
1373                 dump_hex("client_write_MAC_key:%s\n",
1374                         tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key)
1375                 );
1376                 dump_hex("client_write_key:%s\n",
1377                         tls->client_write_key, sizeof(tls->client_write_key)
1378                 );
1379         }
1380 }
1381
1382 static const uint8_t rec_CHANGE_CIPHER_SPEC[] = {
1383         RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01,
1384         01
1385 };
1386
1387 static void send_change_cipher_spec(tls_state_t *tls)
1388 {
1389         dbg(">> CHANGE_CIPHER_SPEC\n");
1390         xwrite(tls->ofd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC));
1391 }
1392
1393 // 7.4.9.  Finished
1394 // A Finished message is always sent immediately after a change
1395 // cipher spec message to verify that the key exchange and
1396 // authentication processes were successful.  It is essential that a
1397 // change cipher spec message be received between the other handshake
1398 // messages and the Finished message.
1399 //...
1400 // The Finished message is the first one protected with the just
1401 // negotiated algorithms, keys, and secrets.  Recipients of Finished
1402 // messages MUST verify that the contents are correct.  Once a side
1403 // has sent its Finished message and received and validated the
1404 // Finished message from its peer, it may begin to send and receive
1405 // application data over the connection.
1406 //...
1407 // struct {
1408 //     opaque verify_data[verify_data_length];
1409 // } Finished;
1410 //
1411 // verify_data
1412 //    PRF(master_secret, finished_label, Hash(handshake_messages))
1413 //       [0..verify_data_length-1];
1414 //
1415 // finished_label
1416 //    For Finished messages sent by the client, the string
1417 //    "client finished".  For Finished messages sent by the server,
1418 //    the string "server finished".
1419 //
1420 // Hash denotes a Hash of the handshake messages.  For the PRF
1421 // defined in Section 5, the Hash MUST be the Hash used as the basis
1422 // for the PRF.  Any cipher suite which defines a different PRF MUST
1423 // also define the Hash to use in the Finished computation.
1424 //
1425 // In previous versions of TLS, the verify_data was always 12 octets
1426 // long.  In the current version of TLS, it depends on the cipher
1427 // suite.  Any cipher suite which does not explicitly specify
1428 // verify_data_length has a verify_data_length equal to 12.  This
1429 // includes all existing cipher suites.
1430 static void send_client_finished(tls_state_t *tls)
1431 {
1432         struct finished {
1433                 uint8_t type;
1434                 uint8_t len24_hi, len24_mid, len24_lo;
1435                 uint8_t prf_result[12];
1436         };
1437         struct finished *record = tls_get_outbuf(tls, sizeof(*record));
1438         uint8_t handshake_hash[SHA256_OUTSIZE];
1439
1440         fill_handshake_record_hdr(record, HANDSHAKE_FINISHED, sizeof(*record));
1441
1442         sha256_peek(&tls->hsd->handshake_sha256_ctx, handshake_hash);
1443         prf_hmac_sha256(record->prf_result, sizeof(record->prf_result),
1444                         tls->hsd->master_secret, sizeof(tls->hsd->master_secret),
1445                         "client finished",
1446                         handshake_hash, sizeof(handshake_hash)
1447         );
1448         dump_hex("from secret: %s\n", tls->hsd->master_secret, sizeof(tls->hsd->master_secret));
1449         dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1);
1450         dump_hex("%s\n", handshake_hash, sizeof(handshake_hash));
1451         dump_hex("=> digest: %s\n", record->prf_result, sizeof(record->prf_result));
1452
1453         dbg(">> FINISHED\n");
1454         xwrite_encrypted(tls, sizeof(*record), RECORD_TYPE_HANDSHAKE);
1455 }
1456
1457 void FAST_FUNC tls_handshake(tls_state_t *tls, const char *sni)
1458 {
1459         // Client              RFC 5246                Server
1460         // (*) - optional messages, not always sent
1461         //
1462         // ClientHello          ------->
1463         //                                        ServerHello
1464         //                                       Certificate*
1465         //                                 ServerKeyExchange*
1466         //                                CertificateRequest*
1467         //                      <-------      ServerHelloDone
1468         // Certificate*
1469         // ClientKeyExchange
1470         // CertificateVerify*
1471         // [ChangeCipherSpec]
1472         // Finished             ------->
1473         //                                 [ChangeCipherSpec]
1474         //                      <-------             Finished
1475         // Application Data     <------>     Application Data
1476         int len;
1477
1478         tls->hsd = xzalloc(sizeof(*tls->hsd));
1479         sha256_begin(&tls->hsd->handshake_sha256_ctx);
1480
1481         send_client_hello(tls, sni);
1482         get_server_hello(tls);
1483
1484         // RFC 5246
1485         // The server MUST send a Certificate message whenever the agreed-
1486         // upon key exchange method uses certificates for authentication
1487         // (this includes all key exchange methods defined in this document
1488         // except DH_anon).  This message will always immediately follow the
1489         // ServerHello message.
1490         //
1491         // IOW: in practice, Certificate *always* follows.
1492         // (for example, kernel.org does not even accept DH_anon cipher id)
1493         get_server_cert(tls);
1494
1495         len = tls_xread_handshake_block(tls, 4);
1496         if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_SERVER_KEY_EXCHANGE) {
1497                 // 459 bytes:
1498                 // 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...
1499                 //SvKey len=455^
1500                 // with TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: 461 bytes:
1501                 // 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...
1502                 dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len);
1503 //probably need to save it
1504                 tls_xread_handshake_block(tls, 4);
1505         }
1506
1507 //      if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_CERTIFICATE_REQUEST) {
1508 //              dbg("<< CERTIFICATE_REQUEST\n");
1509 // RFC 5246: (in response to this,) "If no suitable certificate is available,
1510 // the client MUST send a certificate message containing no
1511 // certificates.  That is, the certificate_list structure has a
1512 // length of zero. ...
1513 // Client certificates are sent using the Certificate structure
1514 // defined in Section 7.4.2."
1515 // (i.e. the same format as server certs)
1516 //              tls_xread_handshake_block(tls, 4);
1517 //      }
1518
1519         if (tls->inbuf[RECHDR_LEN] != HANDSHAKE_SERVER_HELLO_DONE)
1520                 tls_error_die(tls);
1521         // 0e 000000 (len:0)
1522         dbg("<< SERVER_HELLO_DONE\n");
1523
1524         send_client_key_exchange(tls);
1525
1526         send_change_cipher_spec(tls);
1527         /* from now on we should send encrypted */
1528         /* tls->write_seq64_be = 0; - already is */
1529         tls->encrypt_on_write = 1;
1530
1531         send_client_finished(tls);
1532
1533         /* Get CHANGE_CIPHER_SPEC */
1534         len = tls_xread_record(tls);
1535         if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0)
1536                 tls_error_die(tls);
1537         dbg("<< CHANGE_CIPHER_SPEC\n");
1538         if (CIPHER_ID == TLS_RSA_WITH_NULL_SHA256)
1539                 tls->min_encrypted_len_on_read = SHA256_OUTSIZE;
1540         else
1541                 /* all incoming packets now should be encrypted and have IV + MAC + padding */
1542                 tls->min_encrypted_len_on_read = AES_BLOCKSIZE + SHA256_OUTSIZE + AES_BLOCKSIZE;
1543
1544         /* Get (encrypted) FINISHED from the server */
1545         len = tls_xread_record(tls);
1546         if (len < 4 || tls->inbuf[RECHDR_LEN] != HANDSHAKE_FINISHED)
1547                 tls_error_die(tls);
1548         dbg("<< FINISHED\n");
1549         /* application data can be sent/received */
1550
1551         /* free handshake data */
1552 //      if (PARANOIA)
1553 //              memset(tls->hsd, 0, sizeof(*tls->hsd));
1554         free(tls->hsd);
1555         tls->hsd = NULL;
1556 }
1557
1558 static void tls_xwrite(tls_state_t *tls, int len)
1559 {
1560         dbg(">> DATA\n");
1561         xwrite_encrypted(tls, len, RECORD_TYPE_APPLICATION_DATA);
1562 }
1563
1564 // To run a test server using openssl:
1565 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
1566 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1
1567 //
1568 // Unencryped SHA256 example:
1569 // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
1570 // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL
1571 // openssl s_client -connect 127.0.0.1:4433 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL-SHA256
1572
1573 void FAST_FUNC tls_run_copy_loop(tls_state_t *tls)
1574 {
1575         fd_set readfds;
1576         int inbuf_size;
1577         const int INBUF_STEP = 4 * 1024;
1578
1579 //TODO: convert to poll
1580         /* Select loop copying stdin to ofd, and ifd to stdout */
1581         FD_ZERO(&readfds);
1582         FD_SET(tls->ifd, &readfds);
1583         FD_SET(STDIN_FILENO, &readfds);
1584
1585         inbuf_size = INBUF_STEP;
1586         for (;;) {
1587                 fd_set testfds;
1588                 int nread;
1589
1590                 testfds = readfds;
1591                 if (select(tls->ifd + 1, &testfds, NULL, NULL, NULL) < 0)
1592                         bb_perror_msg_and_die("select");
1593
1594                 if (FD_ISSET(STDIN_FILENO, &testfds)) {
1595                         void *buf;
1596
1597                         dbg("STDIN HAS DATA\n");
1598                         buf = tls_get_outbuf(tls, inbuf_size);
1599                         nread = safe_read(STDIN_FILENO, buf, inbuf_size);
1600                         if (nread < 1) {
1601                                 /* We'd want to do this: */
1602                                 /* Close outgoing half-connection so they get EOF,
1603                                  * but leave incoming alone so we can see response
1604                                  */
1605                                 //shutdown(tls->ofd, SHUT_WR);
1606                                 /* But TLS has no way to encode this,
1607                                  * doubt it's ok to do it "raw"
1608                                  */
1609                                 FD_CLR(STDIN_FILENO, &readfds);
1610                                 tls_free_outbuf(tls); /* mem usage optimization */
1611                         } else {
1612                                 if (nread == inbuf_size) {
1613                                         /* TLS has per record overhead, if input comes fast,
1614                                          * read, encrypt and send bigger chunks
1615                                          */
1616                                         inbuf_size += INBUF_STEP;
1617                                         if (inbuf_size > MAX_OUTBUF)
1618                                                 inbuf_size = MAX_OUTBUF;
1619                                 }
1620                                 tls_xwrite(tls, nread);
1621                         }
1622                 }
1623                 if (FD_ISSET(tls->ifd, &testfds)) {
1624                         dbg("NETWORK HAS DATA\n");
1625  read_record:
1626                         nread = tls_xread_record(tls);
1627                         if (nread < 1) {
1628                                 /* TLS protocol has no real concept of one-sided shutdowns:
1629                                  * if we get "TLS EOF" from the peer, writes will fail too
1630                                  */
1631                                 //FD_CLR(tls->ifd, &readfds);
1632                                 //close(STDOUT_FILENO);
1633                                 //tls_free_inbuf(tls); /* mem usage optimization */
1634                                 //continue;
1635                                 break;
1636                         }
1637                         if (tls->inbuf[0] != RECORD_TYPE_APPLICATION_DATA)
1638                                 bb_error_msg_and_die("unexpected record type %d", tls->inbuf[0]);
1639                         xwrite(STDOUT_FILENO, tls->inbuf + RECHDR_LEN, nread);
1640                         /* We may already have a complete next record buffered,
1641                          * can process it without network reads (and possible blocking)
1642                          */
1643                         if (tls_has_buffered_record(tls))
1644                                 goto read_record;
1645                 }
1646         }
1647 }