/* * Copyright (C) 2017 Denys Vlasenko * * Licensed under GPLv2, see file LICENSE in this source tree. */ //config:config TLS //config: bool "tls (debugging)" //config: default n //applet:IF_TLS(APPLET(tls, BB_DIR_USR_BIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_TLS) += tls.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm_montgomery_reduce.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm_mul_comba.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm_sqr_comba.o //kbuild:lib-$(CONFIG_TLS) += tls_rsa.o //kbuild:lib-$(CONFIG_TLS) += tls_aes.o ////kbuild:lib-$(CONFIG_TLS) += tls_aes_gcm.o //usage:#define tls_trivial_usage //usage: "HOST[:PORT]" //usage:#define tls_full_usage "\n\n" #include "tls.h" //#include "common_bufsiz.h" #define TLS_DEBUG 1 #define TLS_DEBUG_HASH 0 #define TLS_DEBUG_DER 0 #define TLS_DEBUG_FIXED_SECRETS 0 #if TLS_DEBUG # define dbg(...) fprintf(stderr, __VA_ARGS__) #else # define dbg(...) ((void)0) #endif #if TLS_DEBUG_DER # define dbg_der(...) fprintf(stderr, __VA_ARGS__) #else # define dbg_der(...) ((void)0) #endif #if 0 # define dump_raw_out(...) dump_hex(__VA_ARGS__) #else # define dump_raw_out(...) ((void)0) #endif #if 0 # define dump_raw_in(...) dump_hex(__VA_ARGS__) #else # define dump_raw_in(...) ((void)0) #endif #define RECORD_TYPE_CHANGE_CIPHER_SPEC 20 #define RECORD_TYPE_ALERT 21 #define RECORD_TYPE_HANDSHAKE 22 #define RECORD_TYPE_APPLICATION_DATA 23 #define HANDSHAKE_HELLO_REQUEST 0 #define HANDSHAKE_CLIENT_HELLO 1 #define HANDSHAKE_SERVER_HELLO 2 #define HANDSHAKE_HELLO_VERIFY_REQUEST 3 #define HANDSHAKE_NEW_SESSION_TICKET 4 #define HANDSHAKE_CERTIFICATE 11 #define HANDSHAKE_SERVER_KEY_EXCHANGE 12 #define HANDSHAKE_CERTIFICATE_REQUEST 13 #define HANDSHAKE_SERVER_HELLO_DONE 14 #define HANDSHAKE_CERTIFICATE_VERIFY 15 #define HANDSHAKE_CLIENT_KEY_EXCHANGE 16 #define HANDSHAKE_FINISHED 20 #define SSL_NULL_WITH_NULL_NULL 0x0000 #define SSL_RSA_WITH_NULL_MD5 0x0001 #define SSL_RSA_WITH_NULL_SHA 0x0002 #define SSL_RSA_WITH_RC4_128_MD5 0x0004 #define SSL_RSA_WITH_RC4_128_SHA 0x0005 #define SSL_RSA_WITH_3DES_EDE_CBC_SHA 0x000A /* 10 */ #define TLS_RSA_WITH_AES_128_CBC_SHA 0x002F /* 47 */ #define TLS_RSA_WITH_AES_256_CBC_SHA 0x0035 /* 53 */ #define TLS_RSA_WITH_NULL_SHA256 0x003B /* 59 */ #define TLS_EMPTY_RENEGOTIATION_INFO_SCSV 0x00FF #define TLS_RSA_WITH_IDEA_CBC_SHA 0x0007 /* 7 */ #define SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA 0x0016 /* 22 */ #define SSL_DH_anon_WITH_RC4_128_MD5 0x0018 /* 24 */ #define SSL_DH_anon_WITH_3DES_EDE_CBC_SHA 0x001B /* 27 */ #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA 0x0033 /* 51 */ #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA 0x0039 /* 57 */ #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 0x0067 /* 103 */ #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 0x006B /* 107 */ #define TLS_DH_anon_WITH_AES_128_CBC_SHA 0x0034 /* 52 */ #define TLS_DH_anon_WITH_AES_256_CBC_SHA 0x003A /* 58 */ #define TLS_RSA_WITH_AES_128_CBC_SHA256 0x003C /* 60 */ #define TLS_RSA_WITH_AES_256_CBC_SHA256 0x003D /* 61 */ #define TLS_RSA_WITH_SEED_CBC_SHA 0x0096 /* 150 */ #define TLS_PSK_WITH_AES_128_CBC_SHA 0x008C /* 140 */ #define TLS_PSK_WITH_AES_128_CBC_SHA256 0x00AE /* 174 */ #define TLS_PSK_WITH_AES_256_CBC_SHA384 0x00AF /* 175 */ #define TLS_PSK_WITH_AES_256_CBC_SHA 0x008D /* 141 */ #define TLS_DHE_PSK_WITH_AES_128_CBC_SHA 0x0090 /* 144 */ #define TLS_DHE_PSK_WITH_AES_256_CBC_SHA 0x0091 /* 145 */ #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA 0xC004 /* 49156 */ #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA 0xC005 /* 49157 */ #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA 0xC009 /* 49161 */ #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA 0xC00A /* 49162 */ #define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA 0xC012 /* 49170 */ #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 0xC013 /* 49171 */ #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA 0xC014 /* 49172 */ #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA 0xC00E /* 49166 */ #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA 0xC00F /* 49167 */ #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 0xC023 /* 49187 */ #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024 /* 49188 */ #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 0xC025 /* 49189 */ #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 0xC026 /* 49190 */ #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 0xC027 /* 49191 */ #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 0xC028 /* 49192 */ #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256 0xC029 /* 49193 */ #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384 0xC02A /* 49194 */ // RFC 5288 "AES Galois Counter Mode (GCM) Cipher Suites for TLS" #define TLS_RSA_WITH_AES_128_GCM_SHA256 0x009C /* 156 */ #define TLS_RSA_WITH_AES_256_GCM_SHA384 0x009D /* 157 */ #define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B /* 49195 */ #define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C /* 49196 */ #define TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 0xC02D /* 49197 */ #define TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 0xC02E /* 49198 */ #define TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 0xC02F /* 49199 */ #define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 0xC030 /* 49200 */ #define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 0xC031 /* 49201 */ #define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 0xC032 /* 49202 */ //Tested against kernel.org: //TLS 1.1 //#define TLS_MAJ 3 //#define TLS_MIN 2 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE //TLS 1.2 #define TLS_MAJ 3 #define TLS_MIN 3 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE *** matrixssl uses this on my box //#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE // All GCMs: //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 // ok, recvs SERVER_KEY_EXCHANGE //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_RSA_WITH_AES_256_GCM_SHA384 // ok, no SERVER_KEY_EXCHANGE //#define CIPHER_ID TLS_RSA_WITH_AES_128_GCM_SHA256 // ok, no SERVER_KEY_EXCHANGE *** select this? //#define CIPHER_ID TLS_DH_anon_WITH_AES_256_CBC_SHA // SSL_ALERT_HANDSHAKE_FAILURE //^^^^^^^^^^^^^^^^^^^^^^^ (tested b/c this one doesn't req server certs... no luck) //test TLS_RSA_WITH_AES_128_CBC_SHA, in TLS 1.2 it's mandated to be always supported // works against "openssl s_server -cipher NULL" // and against wolfssl-3.9.10-stable/examples/server/server.c: //#define CIPHER_ID TLS_RSA_WITH_NULL_SHA256 // for testing (does everything except encrypting) // works against wolfssl-3.9.10-stable/examples/server/server.c #define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE enum { SHA256_INSIZE = 64, SHA256_OUTSIZE = 32, AES_BLOCKSIZE = 16, AES128_KEYSIZE = 16, AES256_KEYSIZE = 32, RSA_PREMASTER_SIZE = 48, RECHDR_LEN = 5, MAX_TLS_RECORD = (1 << 14), /* 8 = 3+5. 3 extra bytes result in record data being 32-bit aligned */ OUTBUF_PFX = 8 + AES_BLOCKSIZE, /* header + IV */ OUTBUF_SFX = SHA256_OUTSIZE + AES_BLOCKSIZE, /* MAC + padding */ MAX_OUTBUF = MAX_TLS_RECORD - OUTBUF_PFX - OUTBUF_SFX, }; struct record_hdr { uint8_t type; uint8_t proto_maj, proto_min; uint8_t len16_hi, len16_lo; }; typedef struct tls_state { int fd; psRsaKey_t server_rsa_pub_key; sha256_ctx_t handshake_sha256_ctx; uint8_t client_and_server_rand32[2 * 32]; uint8_t master_secret[48]; uint8_t encrypt_on_write; int min_encrypted_len_on_read; uint8_t client_write_MAC_key[SHA256_OUTSIZE]; uint8_t server_write_MAC_key[SHA256_OUTSIZE]; uint8_t client_write_key[AES256_KEYSIZE]; uint8_t server_write_key[AES256_KEYSIZE]; // RFC 5246 // sequence number // Each connection state contains a sequence number, which is // maintained separately for read and write states. The sequence // number MUST be set to zero whenever a connection state is made the // active state. Sequence numbers are of type uint64 and may not // exceed 2^64-1. uint64_t write_seq64_be; int outbuf_size; uint8_t *outbuf; // RFC 5246 // | 6.2.1. Fragmentation // | The record layer fragments information blocks into TLSPlaintext // | records carrying data in chunks of 2^14 bytes or less. Client // | message boundaries are not preserved in the record layer (i.e., // | multiple client messages of the same ContentType MAY be coalesced // | into a single TLSPlaintext record, or a single message MAY be // | fragmented across several records) // |... // | length // | The length (in bytes) of the following TLSPlaintext.fragment. // | The length MUST NOT exceed 2^14. // |... // | 6.2.2. Record Compression and Decompression // |... // | Compression must be lossless and may not increase the content length // | by more than 1024 bytes. If the decompression function encounters a // | TLSCompressed.fragment that would decompress to a length in excess of // | 2^14 bytes, it MUST report a fatal decompression failure error. // |... // | length // | The length (in bytes) of the following TLSCompressed.fragment. // | The length MUST NOT exceed 2^14 + 1024. // // Since our buffer also contains 5-byte headers, make it a bit bigger: int insize; int tail; //needed? uint64_t align____; uint8_t inbuf[20*1024]; } tls_state_t; static unsigned get24be(const uint8_t *p) { return 0x100*(0x100*p[0] + p[1]) + p[2]; } #if TLS_DEBUG static void dump_hex(const char *fmt, const void *vp, int len) { char hexbuf[32 * 1024 + 4]; const uint8_t *p = vp; bin2hex(hexbuf, (void*)p, len)[0] = '\0'; dbg(fmt, hexbuf); } static void dump_tls_record(const void *vp, int len) { const uint8_t *p = vp; while (len > 0) { unsigned xhdr_len; if (len < RECHDR_LEN) { dump_hex("< |%s|\n", p, len); return; } xhdr_len = 0x100*p[3] + p[4]; dbg("< hdr_type:%u ver:%u.%u len:%u", p[0], p[1], p[2], xhdr_len); p += RECHDR_LEN; len -= RECHDR_LEN; if (len >= 4 && p[-RECHDR_LEN] == RECORD_TYPE_HANDSHAKE) { unsigned len24 = get24be(p + 1); dbg(" type:%u len24:%u", p[0], len24); } if (xhdr_len > len) xhdr_len = len; dump_hex(" |%s|\n", p, xhdr_len); p += xhdr_len; len -= xhdr_len; } } #else # define dump_hex(...) ((void)0) # define dump_tls_record(...) ((void)0) #endif void tls_get_random(void *buf, unsigned len) { if (len != open_read_close("/dev/urandom", buf, len)) xfunc_die(); } //TODO rename this to sha256_hash, and sha256_hash -> sha256_update static void hash_sha256(uint8_t out[SHA256_OUTSIZE], const void *data, unsigned size) { sha256_ctx_t ctx; sha256_begin(&ctx); sha256_hash(&ctx, data, size); sha256_end(&ctx, out); } /* Nondestructively see the current hash value */ static void sha256_peek(sha256_ctx_t *ctx, void *buffer) { sha256_ctx_t ctx_copy = *ctx; sha256_end(&ctx_copy, buffer); } #if TLS_DEBUG_HASH static void sha256_hash_dbg(const char *fmt, sha256_ctx_t *ctx, const void *buffer, size_t len) { uint8_t h[SHA256_OUTSIZE]; sha256_hash(ctx, buffer, len); dump_hex(fmt, buffer, len); dbg(" (%u) ", (int)len); sha256_peek(ctx, h); dump_hex("%s\n", h, SHA256_OUTSIZE); } #else # define sha256_hash_dbg(fmt, ctx, buffer, len) \ sha256_hash(ctx, buffer, len) #endif // RFC 2104 // HMAC(key, text) based on a hash H (say, sha256) is: // ipad = [0x36 x INSIZE] // opad = [0x5c x INSIZE] // HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text)) // // H(key XOR opad) and H(key XOR ipad) can be precomputed // if we often need HMAC hmac with the same key. // // text is often given in disjoint pieces. static void hmac_sha256_precomputed_v(uint8_t out[SHA256_OUTSIZE], sha256_ctx_t *hashed_key_xor_ipad, sha256_ctx_t *hashed_key_xor_opad, va_list va) { uint8_t *text; /* hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */ /* hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */ /* calculate out = H((key XOR ipad) + text) */ while ((text = va_arg(va, uint8_t*)) != NULL) { unsigned text_size = va_arg(va, unsigned); sha256_hash(hashed_key_xor_ipad, text, text_size); } sha256_end(hashed_key_xor_ipad, out); /* out = H((key XOR opad) + out) */ sha256_hash(hashed_key_xor_opad, out, SHA256_OUTSIZE); sha256_end(hashed_key_xor_opad, out); } static void hmac_sha256(uint8_t out[SHA256_OUTSIZE], uint8_t *key, unsigned key_size, ...) { sha256_ctx_t hashed_key_xor_ipad; sha256_ctx_t hashed_key_xor_opad; uint8_t key_xor_ipad[SHA256_INSIZE]; uint8_t key_xor_opad[SHA256_INSIZE]; uint8_t tempkey[SHA256_OUTSIZE]; va_list va; int i; va_start(va, key_size); // "The authentication key can be of any length up to INSIZE, the // block length of the hash function. Applications that use keys longer // than INSIZE bytes will first hash the key using H and then use the // resultant OUTSIZE byte string as the actual key to HMAC." if (key_size > SHA256_INSIZE) { hash_sha256(tempkey, key, key_size); key = tempkey; key_size = SHA256_OUTSIZE; } for (i = 0; i < key_size; i++) { key_xor_ipad[i] = key[i] ^ 0x36; key_xor_opad[i] = key[i] ^ 0x5c; } for (; i < SHA256_INSIZE; i++) { key_xor_ipad[i] = 0x36; key_xor_opad[i] = 0x5c; } sha256_begin(&hashed_key_xor_ipad); sha256_hash(&hashed_key_xor_ipad, key_xor_ipad, SHA256_INSIZE); sha256_begin(&hashed_key_xor_opad); sha256_hash(&hashed_key_xor_opad, key_xor_opad, SHA256_INSIZE); hmac_sha256_precomputed_v(out, &hashed_key_xor_ipad, &hashed_key_xor_opad, va); va_end(va); } // RFC 5246: // 5. HMAC and the Pseudorandom Function //... // In this section, we define one PRF, based on HMAC. This PRF with the // SHA-256 hash function is used for all cipher suites defined in this // document and in TLS documents published prior to this document when // TLS 1.2 is negotiated. //... // P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) + // HMAC_hash(secret, A(2) + seed) + // HMAC_hash(secret, A(3) + seed) + ... // where + indicates concatenation. // A() is defined as: // A(0) = seed // A(1) = HMAC_hash(secret, A(0)) = HMAC_hash(secret, seed) // A(i) = HMAC_hash(secret, A(i-1)) // P_hash can be iterated as many times as necessary to produce the // required quantity of data. For example, if P_SHA256 is being used to // create 80 bytes of data, it will have to be iterated three times // (through A(3)), creating 96 bytes of output data; the last 16 bytes // of the final iteration will then be discarded, leaving 80 bytes of // output data. // // TLS's PRF is created by applying P_hash to the secret as: // // PRF(secret, label, seed) = P_(secret, label + seed) // // The label is an ASCII string. static void prf_hmac_sha256( uint8_t *outbuf, unsigned outbuf_size, uint8_t *secret, unsigned secret_size, const char *label, uint8_t *seed, unsigned seed_size) { uint8_t a[SHA256_OUTSIZE]; uint8_t *out_p = outbuf; unsigned label_size = strlen(label); /* In P_hash() calculation, "seed" is "label + seed": */ #define SEED label, label_size, seed, seed_size #define SECRET secret, secret_size #define A a, (int)(sizeof(a)) /* A(1) = HMAC_hash(secret, seed) */ hmac_sha256(a, SECRET, SEED, NULL); //TODO: convert hmac_sha256 to precomputed for(;;) { /* HMAC_hash(secret, A(1) + seed) */ if (outbuf_size <= SHA256_OUTSIZE) { /* Last, possibly incomplete, block */ /* (use a[] as temp buffer) */ hmac_sha256(a, SECRET, A, SEED, NULL); memcpy(out_p, a, outbuf_size); return; } /* Not last block. Store directly to result buffer */ hmac_sha256(out_p, SECRET, A, SEED, NULL); out_p += SHA256_OUTSIZE; outbuf_size -= SHA256_OUTSIZE; /* A(2) = HMAC_hash(secret, A(1)) */ hmac_sha256(a, SECRET, A, NULL); } #undef A #undef SECRET #undef SEED } static tls_state_t *new_tls_state(void) { tls_state_t *tls = xzalloc(sizeof(*tls)); tls->fd = -1; sha256_begin(&tls->handshake_sha256_ctx); return tls; } static void tls_error_die(tls_state_t *tls) { dump_tls_record(tls->inbuf, tls->insize + tls->tail); bb_error_msg_and_die("TODO: useful diagnostic about %p", tls); } static void tls_free_outbuf(tls_state_t *tls) { free(tls->outbuf); tls->outbuf_size = 0; tls->outbuf = NULL; } static void *tls_get_outbuf(tls_state_t *tls, int len) { if (len > MAX_OUTBUF) xfunc_die(); if (tls->outbuf_size < len + OUTBUF_PFX + OUTBUF_SFX) { tls->outbuf_size = len + OUTBUF_PFX + OUTBUF_SFX; tls->outbuf = xrealloc(tls->outbuf, tls->outbuf_size); } return tls->outbuf + OUTBUF_PFX; } static void xwrite_encrypted(tls_state_t *tls, unsigned size, unsigned type) { uint8_t *buf = tls->outbuf + OUTBUF_PFX; struct record_hdr *xhdr; uint8_t padding_length; xhdr = (void*)(buf - RECHDR_LEN); if (CIPHER_ID != TLS_RSA_WITH_NULL_SHA256) xhdr = (void*)(buf - RECHDR_LEN - AES_BLOCKSIZE); /* place for IV */ xhdr->type = type; xhdr->proto_maj = TLS_MAJ; xhdr->proto_min = TLS_MIN; /* fake unencrypted record header len for MAC calculation */ xhdr->len16_hi = size >> 8; xhdr->len16_lo = size & 0xff; /* Calculate MAC signature */ //TODO: convert hmac_sha256 to precomputed hmac_sha256(buf + size, tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key), &tls->write_seq64_be, sizeof(tls->write_seq64_be), xhdr, RECHDR_LEN, buf, size, NULL); tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be)); size += SHA256_OUTSIZE; // RFC 5246 // 6.2.3.1. Null or Standard Stream Cipher // // Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6) // convert TLSCompressed.fragment structures to and from stream // TLSCiphertext.fragment structures. // // stream-ciphered struct { // opaque content[TLSCompressed.length]; // opaque MAC[SecurityParameters.mac_length]; // } GenericStreamCipher; // // The MAC is generated as: // MAC(MAC_write_key, seq_num + // TLSCompressed.type + // TLSCompressed.version + // TLSCompressed.length + // TLSCompressed.fragment); // where "+" denotes concatenation. // seq_num // The sequence number for this record. // MAC // The MAC algorithm specified by SecurityParameters.mac_algorithm. // // Note that the MAC is computed before encryption. The stream cipher // encrypts the entire block, including the MAC. //... // Appendix C. Cipher Suite Definitions //... // MAC Algorithm mac_length mac_key_length // -------- ----------- ---------- -------------- // SHA HMAC-SHA1 20 20 // SHA256 HMAC-SHA256 32 32 if (CIPHER_ID == TLS_RSA_WITH_NULL_SHA256) { /* No encryption, only signing */ xhdr->len16_hi = size >> 8; xhdr->len16_lo = size & 0xff; dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size); xwrite(tls->fd, xhdr, RECHDR_LEN + size); dbg("wrote %u bytes (NULL crypt, SHA256 hash)\n", size); return; } // 6.2.3.2. CBC Block Cipher // For block ciphers (such as 3DES or AES), the encryption and MAC // functions convert TLSCompressed.fragment structures to and from block // TLSCiphertext.fragment structures. // struct { // opaque IV[SecurityParameters.record_iv_length]; // block-ciphered struct { // opaque content[TLSCompressed.length]; // opaque MAC[SecurityParameters.mac_length]; // uint8 padding[GenericBlockCipher.padding_length]; // uint8 padding_length; // }; // } GenericBlockCipher; //... // IV // The Initialization Vector (IV) SHOULD be chosen at random, and // MUST be unpredictable. Note that in versions of TLS prior to 1.1, // there was no IV field (...). For block ciphers, the IV length is // of length SecurityParameters.record_iv_length, which is equal to the // SecurityParameters.block_size. // padding // Padding that is added to force the length of the plaintext to be // an integral multiple of the block cipher's block length. // padding_length // The padding length MUST be such that the total size of the // GenericBlockCipher structure is a multiple of the cipher's block // length. Legal values range from zero to 255, inclusive. //... // Appendix C. Cipher Suite Definitions //... // Key IV Block // Cipher Type Material Size Size // ------------ ------ -------- ---- ----- // AES_128_CBC Block 16 16 16 // AES_256_CBC Block 32 16 16 /* Build IV+content+MAC+padding in outbuf */ tls_get_random(buf - AES_BLOCKSIZE, AES_BLOCKSIZE); /* IV */ dbg("before crypt: 5 hdr + %u data + %u hash bytes\n", size, SHA256_OUTSIZE); // RFC is talking nonsense: // Padding that is added to force the length of the plaintext to be // an integral multiple of the block cipher's block length. // WRONG. _padding+padding_length_, not just _padding_, // pads the data. // IOW: padding_length is the last byte of padding[] array, // contrary to what RFC depicts. // // What actually happens is that there is always padding. // If you need one byte to reach BLOCKSIZE, this byte is 0x00. // If you need two bytes, they are both 0x01. // If you need three, they are 0x02,0x02,0x02. And so on. // If you need no bytes to reach BLOCKSIZE, you have to pad a full // BLOCKSIZE with bytes of value (BLOCKSIZE-1). // It's ok to have more than minimum padding, but we do minimum. padding_length = (~size) & (AES_BLOCKSIZE - 1); do { buf[size++] = padding_length; /* padding */ } while ((size & (AES_BLOCKSIZE - 1)) != 0); /* Encrypt content+MAC+padding in place */ { psCipherContext_t ctx; psAesInit(&ctx, buf - AES_BLOCKSIZE, /* IV */ tls->client_write_key, sizeof(tls->client_write_key) ); psAesEncrypt(&ctx, buf, /* plaintext */ buf, /* ciphertext */ size ); } /* Write out */ dbg("writing 5 + %u IV + %u encrypted bytes, padding_length:0x%02x\n", AES_BLOCKSIZE, size, padding_length); size += AES_BLOCKSIZE; /* + IV */ xhdr->len16_hi = size >> 8; xhdr->len16_lo = size & 0xff; dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size); xwrite(tls->fd, xhdr, RECHDR_LEN + size); dbg("wrote %u bytes\n", (int)RECHDR_LEN + size); } static void xwrite_and_update_handshake_hash(tls_state_t *tls, unsigned size) { if (!tls->encrypt_on_write) { uint8_t *buf = tls->outbuf + OUTBUF_PFX; struct record_hdr *xhdr = (void*)(buf - RECHDR_LEN); xhdr->type = RECORD_TYPE_HANDSHAKE; xhdr->proto_maj = TLS_MAJ; xhdr->proto_min = TLS_MIN; xhdr->len16_hi = size >> 8; xhdr->len16_lo = size & 0xff; dump_raw_out(">> %s\n", xhdr, RECHDR_LEN + size); xwrite(tls->fd, xhdr, RECHDR_LEN + size); dbg("wrote %u bytes\n", (int)RECHDR_LEN + size); /* Handshake hash does not include record headers */ sha256_hash_dbg(">> sha256:%s", &tls->handshake_sha256_ctx, buf, size); return; } xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE); } static int tls_has_buffered_record(tls_state_t *tls) { int buffered = tls->tail; struct record_hdr *xhdr; int rec_size; if (buffered < RECHDR_LEN) return 0; xhdr = (void*)(tls->inbuf + tls->insize); rec_size = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo); if (buffered < rec_size) return 0; return rec_size; } static int tls_xread_record(tls_state_t *tls) { struct record_hdr *xhdr; int sz; int total; int target; again: dbg("insize:%u tail:%u\n", tls->insize, tls->tail); total = tls->tail; if (total != 0) { memmove(tls->inbuf, tls->inbuf + tls->insize, total); //dbg("<< remaining at %d [%d] ", tls->insize, total); //dump_raw_in("<< %s\n", tls->inbuf, total); } errno = 0; target = sizeof(tls->inbuf); for (;;) { if (total >= RECHDR_LEN && target == sizeof(tls->inbuf)) { xhdr = (void*)tls->inbuf; target = RECHDR_LEN + (0x100 * xhdr->len16_hi + xhdr->len16_lo); if (target >= sizeof(tls->inbuf)) { /* malformed input (too long): yell and die */ tls->tail = 0; tls->insize = total; tls_error_die(tls); } /* can also check type/proto_maj/proto_min here */ dbg("xhdr type:%d ver:%d.%d len:%d\n", xhdr->type, xhdr->proto_maj, xhdr->proto_min, 0x100 * xhdr->len16_hi + xhdr->len16_lo ); } /* if total >= target, we have a full packet (and possibly more)... */ if (total - target >= 0) break; sz = safe_read(tls->fd, tls->inbuf + total, sizeof(tls->inbuf) - total); if (sz <= 0) { if (sz == 0 && total == 0) { /* "Abrupt" EOF, no TLS shutdown (seen from kernel.org) */ dbg("EOF (without TLS shutdown) from peer\n"); tls->tail = 0; goto end; } bb_perror_msg_and_die("short read, have only %d", total); } dump_raw_in("<< %s\n", tls->inbuf + total, sz); total += sz; } tls->tail = total - target; tls->insize = target; //dbg("<< stashing at %d [%d] ", tls->insize, tls->tail); //dump_hex("<< %s\n", tls->inbuf + tls->insize, tls->tail); sz = target - RECHDR_LEN; /* Needs to be decrypted? */ if (tls->min_encrypted_len_on_read > SHA256_OUTSIZE) { psCipherContext_t ctx; uint8_t *p = tls->inbuf + RECHDR_LEN; int padding_len; if (sz & (AES_BLOCKSIZE-1) || sz < tls->min_encrypted_len_on_read ) { bb_error_msg_and_die("bad encrypted len:%u", sz); } /* Decrypt content+MAC+padding in place */ psAesInit(&ctx, p, /* IV */ tls->server_write_key, sizeof(tls->server_write_key) ); psAesDecrypt(&ctx, p + AES_BLOCKSIZE, /* ciphertext */ p + AES_BLOCKSIZE, /* plaintext */ sz - AES_BLOCKSIZE ); padding_len = p[sz - 1]; dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[AES_BLOCKSIZE], padding_len); padding_len++; sz -= AES_BLOCKSIZE + SHA256_OUTSIZE + padding_len; if (sz < 0) { bb_error_msg_and_die("bad padding size:%u", padding_len); } if (sz != 0) { /* Skip IV */ memmove(tls->inbuf + RECHDR_LEN, tls->inbuf + RECHDR_LEN + AES_BLOCKSIZE, sz); } } else { /* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */ /* else: no encryption yet on input, subtract zero = NOP */ sz -= tls->min_encrypted_len_on_read; } //dump_hex("<< %s\n", tls->inbuf, RECHDR_LEN + sz); xhdr = (void*)tls->inbuf; if (xhdr->type == RECORD_TYPE_ALERT && sz >= 2) { uint8_t *p = tls->inbuf + RECHDR_LEN; dbg("ALERT size:%d level:%d description:%d\n", sz, p[0], p[1]); if (p[0] == 1) { /*warning */ if (p[1] == 0) { /* warning, close_notify: EOF */ dbg("EOF (TLS encoded) from peer\n"); sz = 0; goto end; } /* discard it, get next record */ goto again; } /* p[0] == 1: fatal error, others: not defined in protocol */ sz = 0; goto end; } /* RFC 5246 is not saying it explicitly, but sha256 hash * in our FINISHED record must include data of incoming packets too! */ if (tls->inbuf[0] == RECORD_TYPE_HANDSHAKE) { sha256_hash_dbg("<< sha256:%s", &tls->handshake_sha256_ctx, tls->inbuf + RECHDR_LEN, sz); } end: dbg("got block len:%u\n", sz); return sz; } /* * DER parsing routines */ static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end) { unsigned len, len1; if (end - der < 2) xfunc_die(); // if ((der[0] & 0x1f) == 0x1f) /* not single-byte item code? */ // xfunc_die(); len = der[1]; /* maybe it's short len */ if (len >= 0x80) { /* no, it's long */ if (len == 0x80 || end - der < (int)(len - 0x7e)) { /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */ /* need 3 or 4 bytes for 81, 82 */ xfunc_die(); } len1 = der[2]; /* if (len == 0x81) it's "ii 81 xx", fetch xx */ if (len > 0x82) { /* >0x82 is "3+ bytes of len", should not happen realistically */ xfunc_die(); } if (len == 0x82) { /* it's "ii 82 xx yy" */ len1 = 0x100*len1 + der[3]; der += 1; /* skip [yy] */ } der += 1; /* skip [xx] */ len = len1; // if (len < 0x80) // xfunc_die(); /* invalid DER: must use short len if can */ } der += 2; /* skip [code]+[1byte] */ if (end - der < (int)len) xfunc_die(); *bodyp = der; return len; } static uint8_t *enter_der_item(uint8_t *der, uint8_t **endp) { uint8_t *new_der; unsigned len = get_der_len(&new_der, der, *endp); dbg_der("entered der @%p:0x%02x len:%u inner_byte @%p:0x%02x\n", der, der[0], len, new_der, new_der[0]); /* Move "end" position to cover only this item */ *endp = new_der + len; return new_der; } static uint8_t *skip_der_item(uint8_t *der, uint8_t *end) { uint8_t *new_der; unsigned len = get_der_len(&new_der, der, end); /* Skip body */ new_der += len; dbg_der("skipped der 0x%02x, next byte 0x%02x\n", der[0], new_der[0]); return new_der; } static void der_binary_to_pstm(pstm_int *pstm_n, uint8_t *der, uint8_t *end) { uint8_t *bin_ptr; unsigned len = get_der_len(&bin_ptr, der, end); dbg_der("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]); pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len); pstm_read_unsigned_bin(pstm_n, bin_ptr, len); //return bin + len; } static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len) { /* Certificate is a DER-encoded data structure. Each DER element has a length, * which makes it easy to skip over large compound elements of any complexity * without parsing them. Example: partial decode of kernel.org certificate: * SEQ 0x05ac/1452 bytes (Certificate): 308205ac * SEQ 0x0494/1172 bytes (tbsCertificate): 30820494 * [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0] 3 bytes: a003 * INTEGER (version): 0201 02 * INTEGER 0x11 bytes (serialNumber): 0211 00 9f85bf664b0cddafca508679501b2be4 * //^^^^^^note: matrixSSL also allows [ASN_CONTEXT_SPECIFIC | ASN_PRIMITIVE | 2] = 0x82 type * SEQ 0x0d bytes (signatureAlgo): 300d * OID 9 bytes: 0609 2a864886f70d01010b (OID_SHA256_RSA_SIG 42.134.72.134.247.13.1.1.11) * NULL: 0500 * SEQ 0x5f bytes (issuer): 305f * SET 11 bytes: 310b * SEQ 9 bytes: 3009 * OID 3 bytes: 0603 550406 * Printable string "FR": 1302 4652 * SET 14 bytes: 310e * SEQ 12 bytes: 300c * OID 3 bytes: 0603 550408 * Printable string "Paris": 1305 5061726973 * SET 14 bytes: 310e * SEQ 12 bytes: 300c * OID 3 bytes: 0603 550407 * Printable string "Paris": 1305 5061726973 * SET 14 bytes: 310e * SEQ 12 bytes: 300c * OID 3 bytes: 0603 55040a * Printable string "Gandi": 1305 47616e6469 * SET 32 bytes: 3120 * SEQ 30 bytes: 301e * OID 3 bytes: 0603 550403 * Printable string "Gandi Standard SSL CA 2": 1317 47616e6469205374616e646172642053534c2043412032 * SEQ 30 bytes (validity): 301e * TIME "161011000000Z": 170d 3136313031313030303030305a * TIME "191011235959Z": 170d 3139313031313233353935395a * SEQ 0x5b/91 bytes (subject): 305b //I did not decode this * 3121301f060355040b1318446f6d61696e20436f * 6e74726f6c2056616c6964617465643121301f06 * 0355040b1318506f73697469766553534c204d75 * 6c74692d446f6d61696e31133011060355040313 * 0a6b65726e656c2e6f7267 * SEQ 0x01a2/418 bytes (subjectPublicKeyInfo): 308201a2 * SEQ 13 bytes (algorithm): 300d * OID 9 bytes: 0609 2a864886f70d010101 (OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1) * NULL: 0500 * BITSTRING 0x018f/399 bytes (publicKey): 0382018f * ????: 00 * //after the zero byte, it appears key itself uses DER encoding: * SEQ 0x018a/394 bytes: 3082018a * INTEGER 0x0181/385 bytes (modulus): 02820181 * 00b1ab2fc727a3bef76780c9349bf3 * ...24 more blocks of 15 bytes each... * 90e895291c6bc8693b65 * INTEGER 3 bytes (exponent): 0203 010001 * [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0x3] 0x01e5 bytes (X509v3 extensions): a38201e5 * SEQ 0x01e1 bytes: 308201e1 * ... * Certificate is a sequence of three elements: * tbsCertificate (SEQ) * signatureAlgorithm (AlgorithmIdentifier) * signatureValue (BIT STRING) * * In turn, tbsCertificate is a sequence of: * version * serialNumber * signatureAlgo (AlgorithmIdentifier) * issuer (Name, has complex structure) * validity (Validity, SEQ of two Times) * subject (Name) * subjectPublicKeyInfo (SEQ) * ... * * subjectPublicKeyInfo is a sequence of: * algorithm (AlgorithmIdentifier) * publicKey (BIT STRING) * * We need Certificate.tbsCertificate.subjectPublicKeyInfo.publicKey */ uint8_t *end = der + len; /* enter "Certificate" item: [der, end) will be only Cert */ der = enter_der_item(der, &end); /* enter "tbsCertificate" item: [der, end) will be only tbsCert */ der = enter_der_item(der, &end); /* skip up to subjectPublicKeyInfo */ der = skip_der_item(der, end); /* version */ der = skip_der_item(der, end); /* serialNumber */ der = skip_der_item(der, end); /* signatureAlgo */ der = skip_der_item(der, end); /* issuer */ der = skip_der_item(der, end); /* validity */ der = skip_der_item(der, end); /* subject */ /* enter subjectPublicKeyInfo */ der = enter_der_item(der, &end); { /* check subjectPublicKeyInfo.algorithm */ static const uint8_t expected[] = { 0x30,0x0d, // SEQ 13 bytes 0x06,0x09, 0x2a,0x86,0x48,0x86,0xf7,0x0d,0x01,0x01,0x01, // OID RSA_KEY_ALG 42.134.72.134.247.13.1.1.1 //0x05,0x00, // NULL }; if (memcmp(der, expected, sizeof(expected)) != 0) bb_error_msg_and_die("not RSA key"); } /* skip subjectPublicKeyInfo.algorithm */ der = skip_der_item(der, end); /* enter subjectPublicKeyInfo.publicKey */ // die_if_not_this_der_type(der, end, 0x03); /* must be BITSTRING */ der = enter_der_item(der, &end); /* parse RSA key: */ //based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note dbg("key bytes:%u, first:0x%02x\n", (int)(end - der), der[0]); if (end - der < 14) xfunc_die(); /* example format: * ignore bits: 00 * SEQ 0x018a/394 bytes: 3082018a * INTEGER 0x0181/385 bytes (modulus): 02820181 XX...XXX * INTEGER 3 bytes (exponent): 0203 010001 */ if (*der != 0) /* "ignore bits", should be 0 */ xfunc_die(); der++; der = enter_der_item(der, &end); /* enter SEQ */ /* memset(tls->server_rsa_pub_key, 0, sizeof(tls->server_rsa_pub_key)); - already is */ der_binary_to_pstm(&tls->server_rsa_pub_key.N, der, end); /* modulus */ der = skip_der_item(der, end); der_binary_to_pstm(&tls->server_rsa_pub_key.e, der, end); /* exponent */ tls->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->server_rsa_pub_key.N); dbg("server_rsa_pub_key.size:%d\n", tls->server_rsa_pub_key.size); } /* * TLS Handshake routines */ static int xread_tls_handshake_block(tls_state_t *tls, int min_len) { struct record_hdr *xhdr; int len = tls_xread_record(tls); xhdr = (void*)tls->inbuf; if (len < min_len || xhdr->type != RECORD_TYPE_HANDSHAKE || xhdr->proto_maj != TLS_MAJ || xhdr->proto_min != TLS_MIN ) { tls_error_die(tls); } dbg("got HANDSHAKE\n"); return len; } static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, unsigned len) { struct handshake_hdr { uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; } *h = buf; len -= 4; h->type = type; h->len24_hi = len >> 16; h->len24_mid = len >> 8; h->len24_lo = len & 0xff; } //TODO: implement RFC 5746 (Renegotiation Indication Extension) - some servers will refuse to work with us otherwise static void send_client_hello(tls_state_t *tls) { struct client_hello { uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; uint8_t proto_maj, proto_min; uint8_t rand32[32]; uint8_t session_id_len; /* uint8_t session_id[]; */ uint8_t cipherid_len16_hi, cipherid_len16_lo; uint8_t cipherid[2 * 1]; /* actually variable */ uint8_t comprtypes_len; uint8_t comprtypes[1]; /* actually variable */ }; struct client_hello *record = tls_get_outbuf(tls, sizeof(*record)); fill_handshake_record_hdr(record, HANDSHAKE_CLIENT_HELLO, sizeof(*record)); record->proto_maj = TLS_MAJ; /* the "requested" version of the protocol, */ record->proto_min = TLS_MIN; /* can be higher than one in record headers */ tls_get_random(record->rand32, sizeof(record->rand32)); if (TLS_DEBUG_FIXED_SECRETS) memset(record->rand32, 0x11, sizeof(record->rand32)); memcpy(tls->client_and_server_rand32, record->rand32, sizeof(record->rand32)); record->session_id_len = 0; record->cipherid_len16_hi = 0; record->cipherid_len16_lo = 2 * 1; record->cipherid[0] = CIPHER_ID >> 8; record->cipherid[1] = CIPHER_ID & 0xff; record->comprtypes_len = 1; record->comprtypes[0] = 0; //TODO: send options, at least SNI. dbg(">> CLIENT_HELLO\n"); xwrite_and_update_handshake_hash(tls, sizeof(*record)); } static void get_server_hello(tls_state_t *tls) { struct server_hello { struct record_hdr xhdr; uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; uint8_t proto_maj, proto_min; uint8_t rand32[32]; /* first 4 bytes are unix time in BE format */ uint8_t session_id_len; uint8_t session_id[32]; uint8_t cipherid_hi, cipherid_lo; uint8_t comprtype; /* extensions may follow, but only those which client offered in its Hello */ }; struct server_hello *hp; uint8_t *cipherid; xread_tls_handshake_block(tls, 74); hp = (void*)tls->inbuf; // 74 bytes: // 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| //SvHl len=70 maj.min unixtime^^^ 28randbytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^ slen sid32bytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cipSel comprSel if (hp->type != HANDSHAKE_SERVER_HELLO || hp->len24_hi != 0 || hp->len24_mid != 0 /* hp->len24_lo checked later */ || hp->proto_maj != TLS_MAJ || hp->proto_min != TLS_MIN ) { tls_error_die(tls); } cipherid = &hp->cipherid_hi; if (hp->session_id_len != 32) { if (hp->session_id_len != 0) tls_error_die(tls); // session_id_len == 0: no session id // "The server // may return an empty session_id to indicate that the session will // not be cached and therefore cannot be resumed." cipherid -= 32; hp->len24_lo += 32; /* what len would be if session id would be present */ } if (hp->len24_lo < 70 || cipherid[0] != (CIPHER_ID >> 8) || cipherid[1] != (CIPHER_ID & 0xff) || cipherid[2] != 0 /* comprtype */ ) { tls_error_die(tls); } dbg("<< SERVER_HELLO\n"); memcpy(tls->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32)); } static void get_server_cert(tls_state_t *tls) { struct record_hdr *xhdr; uint8_t *certbuf; int len, len1; len = xread_tls_handshake_block(tls, 10); xhdr = (void*)tls->inbuf; certbuf = (void*)(xhdr + 1); if (certbuf[0] != HANDSHAKE_CERTIFICATE) tls_error_die(tls); dbg("<< CERTIFICATE\n"); // 4392 bytes: // 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... //Cert len=4388 ChainLen CertLen^ DER encoded X509 starts here. openssl x509 -in FILE -inform DER -noout -text len1 = get24be(certbuf + 1); if (len1 > len - 4) tls_error_die(tls); len = len1; len1 = get24be(certbuf + 4); if (len1 > len - 3) tls_error_die(tls); len = len1; len1 = get24be(certbuf + 7); if (len1 > len - 3) tls_error_die(tls); len = len1; if (len) find_key_in_der_cert(tls, certbuf + 10, len); } static void send_client_key_exchange(tls_state_t *tls) { struct client_key_exchange { uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; /* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */ uint8_t keylen16_hi, keylen16_lo; uint8_t key[4 * 1024]; // size?? }; //FIXME: better size estimate struct client_key_exchange *record = tls_get_outbuf(tls, sizeof(*record)); uint8_t rsa_premaster[RSA_PREMASTER_SIZE]; int len; tls_get_random(rsa_premaster, sizeof(rsa_premaster)); if (TLS_DEBUG_FIXED_SECRETS) memset(rsa_premaster, 0x44, sizeof(rsa_premaster)); // RFC 5246 // "Note: The version number in the PreMasterSecret is the version // offered by the client in the ClientHello.client_version, not the // version negotiated for the connection." rsa_premaster[0] = TLS_MAJ; rsa_premaster[1] = TLS_MIN; len = psRsaEncryptPub(/*pool:*/ NULL, /* psRsaKey_t* */ &tls->server_rsa_pub_key, rsa_premaster, /*inlen:*/ sizeof(rsa_premaster), record->key, sizeof(record->key), data_param_ignored ); record->keylen16_hi = len >> 8; record->keylen16_lo = len & 0xff; len += 2; record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE; record->len24_hi = 0; record->len24_mid = len >> 8; record->len24_lo = len & 0xff; len += 4; dbg(">> CLIENT_KEY_EXCHANGE\n"); xwrite_and_update_handshake_hash(tls, len); // RFC 5246 // For all key exchange methods, the same algorithm is used to convert // the pre_master_secret into the master_secret. The pre_master_secret // should be deleted from memory once the master_secret has been // computed. // master_secret = PRF(pre_master_secret, "master secret", // ClientHello.random + ServerHello.random) // [0..47]; // The master secret is always exactly 48 bytes in length. The length // of the premaster secret will vary depending on key exchange method. prf_hmac_sha256( tls->master_secret, sizeof(tls->master_secret), rsa_premaster, sizeof(rsa_premaster), "master secret", tls->client_and_server_rand32, sizeof(tls->client_and_server_rand32) ); dump_hex("master secret:%s\n", tls->master_secret, sizeof(tls->master_secret)); // RFC 5246 // 6.3. Key Calculation // // The Record Protocol requires an algorithm to generate keys required // by the current connection state (see Appendix A.6) from the security // parameters provided by the handshake protocol. // // The master secret is expanded into a sequence of secure bytes, which // is then split to a client write MAC key, a server write MAC key, a // client write encryption key, and a server write encryption key. Each // of these is generated from the byte sequence in that order. Unused // values are empty. Some AEAD ciphers may additionally require a // client write IV and a server write IV (see Section 6.2.3.3). // // When keys and MAC keys are generated, the master secret is used as an // entropy source. // // To generate the key material, compute // // key_block = PRF(SecurityParameters.master_secret, // "key expansion", // SecurityParameters.server_random + // SecurityParameters.client_random); // // until enough output has been generated. Then, the key_block is // partitioned as follows: // // client_write_MAC_key[SecurityParameters.mac_key_length] // server_write_MAC_key[SecurityParameters.mac_key_length] // client_write_key[SecurityParameters.enc_key_length] // server_write_key[SecurityParameters.enc_key_length] // client_write_IV[SecurityParameters.fixed_iv_length] // server_write_IV[SecurityParameters.fixed_iv_length] { uint8_t tmp64[64]; /* make "server_rand32 + client_rand32" */ memcpy(&tmp64[0] , &tls->client_and_server_rand32[32], 32); memcpy(&tmp64[32], &tls->client_and_server_rand32[0] , 32); prf_hmac_sha256( tls->client_write_MAC_key, 2 * (SHA256_OUTSIZE + AES256_KEYSIZE), // also fills: // server_write_MAC_key[SHA256_OUTSIZE] // client_write_key[AES256_KEYSIZE] // server_write_key[AES256_KEYSIZE] tls->master_secret, sizeof(tls->master_secret), "key expansion", tmp64, 64 ); dump_hex("client_write_MAC_key:%s\n", tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key) ); dump_hex("client_write_key:%s\n", tls->client_write_key, sizeof(tls->client_write_key) ); } } static const uint8_t rec_CHANGE_CIPHER_SPEC[] = { RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01, 01 }; static void send_change_cipher_spec(tls_state_t *tls) { dbg(">> CHANGE_CIPHER_SPEC\n"); xwrite(tls->fd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC)); } // 7.4.9. Finished // A Finished message is always sent immediately after a change // cipher spec message to verify that the key exchange and // authentication processes were successful. It is essential that a // change cipher spec message be received between the other handshake // messages and the Finished message. //... // The Finished message is the first one protected with the just // negotiated algorithms, keys, and secrets. Recipients of Finished // messages MUST verify that the contents are correct. Once a side // has sent its Finished message and received and validated the // Finished message from its peer, it may begin to send and receive // application data over the connection. //... // struct { // opaque verify_data[verify_data_length]; // } Finished; // // verify_data // PRF(master_secret, finished_label, Hash(handshake_messages)) // [0..verify_data_length-1]; // // finished_label // For Finished messages sent by the client, the string // "client finished". For Finished messages sent by the server, // the string "server finished". // // Hash denotes a Hash of the handshake messages. For the PRF // defined in Section 5, the Hash MUST be the Hash used as the basis // for the PRF. Any cipher suite which defines a different PRF MUST // also define the Hash to use in the Finished computation. // // In previous versions of TLS, the verify_data was always 12 octets // long. In the current version of TLS, it depends on the cipher // suite. Any cipher suite which does not explicitly specify // verify_data_length has a verify_data_length equal to 12. This // includes all existing cipher suites. static void send_client_finished(tls_state_t *tls) { struct finished { uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; uint8_t prf_result[12]; }; struct finished *record = tls_get_outbuf(tls, sizeof(*record)); uint8_t handshake_hash[SHA256_OUTSIZE]; fill_handshake_record_hdr(record, HANDSHAKE_FINISHED, sizeof(*record)); sha256_peek(&tls->handshake_sha256_ctx, handshake_hash); prf_hmac_sha256(record->prf_result, sizeof(record->prf_result), tls->master_secret, sizeof(tls->master_secret), "client finished", handshake_hash, sizeof(handshake_hash) ); dump_hex("from secret: %s\n", tls->master_secret, sizeof(tls->master_secret)); dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1); dump_hex("%s\n", handshake_hash, sizeof(handshake_hash)); dump_hex("=> digest: %s\n", record->prf_result, sizeof(record->prf_result)); dbg(">> FINISHED\n"); xwrite_encrypted(tls, sizeof(*record), RECORD_TYPE_HANDSHAKE); } static void tls_handshake(tls_state_t *tls) { // Client RFC 5246 Server // (*) - optional messages, not always sent // // ClientHello -------> // ServerHello // Certificate* // ServerKeyExchange* // CertificateRequest* // <------- ServerHelloDone // Certificate* // ClientKeyExchange // CertificateVerify* // [ChangeCipherSpec] // Finished -------> // [ChangeCipherSpec] // <------- Finished // Application Data <------> Application Data int len; send_client_hello(tls); get_server_hello(tls); // RFC 5246 // The server MUST send a Certificate message whenever the agreed- // upon key exchange method uses certificates for authentication // (this includes all key exchange methods defined in this document // except DH_anon). This message will always immediately follow the // ServerHello message. // // IOW: in practice, Certificate *always* follows. // (for example, kernel.org does not even accept DH_anon cipher id) get_server_cert(tls); len = xread_tls_handshake_block(tls, 4); if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_SERVER_KEY_EXCHANGE) { // 459 bytes: // 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... //SvKey len=455^ // with TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: 461 bytes: // 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... dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len); //probably need to save it xread_tls_handshake_block(tls, 4); } // if (tls->inbuf[RECHDR_LEN] == HANDSHAKE_CERTIFICATE_REQUEST) { // dbg("<< CERTIFICATE_REQUEST\n"); // RFC 5246: (in response to this,) "If no suitable certificate is available, // the client MUST send a certificate message containing no // certificates. That is, the certificate_list structure has a // length of zero. ... // Client certificates are sent using the Certificate structure // defined in Section 7.4.2." // (i.e. the same format as server certs) // xread_tls_handshake_block(tls, 4); // } if (tls->inbuf[RECHDR_LEN] != HANDSHAKE_SERVER_HELLO_DONE) tls_error_die(tls); // 0e 000000 (len:0) dbg("<< SERVER_HELLO_DONE\n"); send_client_key_exchange(tls); send_change_cipher_spec(tls); /* from now on we should send encrypted */ /* tls->write_seq64_be = 0; - already is */ tls->encrypt_on_write = 1; send_client_finished(tls); /* Get CHANGE_CIPHER_SPEC */ len = tls_xread_record(tls); if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0) tls_error_die(tls); dbg("<< CHANGE_CIPHER_SPEC\n"); if (CIPHER_ID == TLS_RSA_WITH_NULL_SHA256) tls->min_encrypted_len_on_read = SHA256_OUTSIZE; else /* all incoming packets now should be encrypted and have IV + MAC + padding */ tls->min_encrypted_len_on_read = AES_BLOCKSIZE + SHA256_OUTSIZE + AES_BLOCKSIZE; /* Get (encrypted) FINISHED from the server */ len = tls_xread_record(tls); if (len < 4 || tls->inbuf[RECHDR_LEN] != HANDSHAKE_FINISHED) tls_error_die(tls); dbg("<< FINISHED\n"); /* application data can be sent/received */ } static void tls_xwrite(tls_state_t *tls, int len) { dbg(">> DATA\n"); xwrite_encrypted(tls, len, RECORD_TYPE_APPLICATION_DATA); } // To run a test server using openssl: // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost' // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 // // Unencryped SHA256 example: // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost' // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL // openssl s_client -connect 127.0.0.1:4433 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL-SHA256 // // Talk to kernel.org: // printf "GET / HTTP/1.1\r\nHost: kernel.org\r\n\r\n" | ./busybox tls kernel.org int tls_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int tls_main(int argc UNUSED_PARAM, char **argv) { tls_state_t *tls; fd_set readfds; int inbuf_size; const int INBUF_STEP = 4 * 1024; int cfd; // INIT_G(); // getopt32(argv, "myopts") if (!argv[1]) bb_show_usage(); cfd = create_and_connect_stream_or_die(argv[1], 443); tls = new_tls_state(); tls->fd = cfd; tls_handshake(tls); /* Select loop copying stdin to cfd, and cfd to stdout */ FD_ZERO(&readfds); FD_SET(cfd, &readfds); FD_SET(STDIN_FILENO, &readfds); inbuf_size = INBUF_STEP; for (;;) { fd_set testfds; int nread; testfds = readfds; if (select(cfd + 1, &testfds, NULL, NULL, NULL) < 0) bb_perror_msg_and_die("select"); if (FD_ISSET(STDIN_FILENO, &testfds)) { void *buf; dbg("STDIN HAS DATA\n"); buf = tls_get_outbuf(tls, inbuf_size); nread = safe_read(STDIN_FILENO, buf, inbuf_size); if (nread < 1) { /* We'd want to do this: */ /* Close outgoing half-connection so they get EOF, * but leave incoming alone so we can see response */ //shutdown(cfd, SHUT_WR); /* But TLS has no way to encode this, * doubt it's ok to do it "raw" */ FD_CLR(STDIN_FILENO, &readfds); tls_free_outbuf(tls); } else { if (nread == inbuf_size) { /* TLS has per record overhead, if input comes fast, * read, encrypt and send bigger chunks */ inbuf_size += INBUF_STEP; if (inbuf_size > MAX_OUTBUF) inbuf_size = MAX_OUTBUF; } tls_xwrite(tls, nread); } } if (FD_ISSET(cfd, &testfds)) { dbg("NETWORK HAS DATA\n"); read_record: nread = tls_xread_record(tls); if (nread < 1) { /* TLS protocol has no real concept of one-sided shutdowns: * if we get "TLS EOF" from the peer, writes will fail too */ //FD_CLR(cfd, &readfds); //close(STDOUT_FILENO); //continue; break; } if (tls->inbuf[0] != RECORD_TYPE_APPLICATION_DATA) bb_error_msg_and_die("unexpected record type %d", tls->inbuf[0]); xwrite(STDOUT_FILENO, tls->inbuf + RECHDR_LEN, nread); /* We may already have a complete next record buffered, * can process it without network reads (and possible blocking) */ if (tls_has_buffered_record(tls)) goto read_record; } } return EXIT_SUCCESS; }