diff options
Diffstat (limited to 'networking/tls.c')
| -rw-r--r-- | networking/tls.c | 341 |
1 files changed, 170 insertions, 171 deletions
diff --git a/networking/tls.c b/networking/tls.c index 60afd30..81820e9 100644 --- a/networking/tls.c +++ b/networking/tls.c @@ -284,6 +284,145 @@ static void sha256_hash_dbg(const char *fmt, sha256_ctx_t *ctx, const void *buff sha256_hash(ctx, buffer, len) #endif /* not TLS_DEBUG >= 2 */ +// 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_<hash>(secret, label + seed) +// +// The label is an ASCII string. +static void tls_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) { @@ -293,11 +432,13 @@ tls_state_t *new_tls_state(void) return tls; } -static void hmac_sha256(uint8_t out[SHA256_OUTSIZE], uint8_t *key, unsigned key_size, ...); - -static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size) +static void tls_error_die(tls_state_t *tls) { -// rfc5246 + dump_tls_record(tls->inbuf, tls->insize + tls->tail); + xfunc_die(); +} + +// RFC 5246 // 6.2.3.1. Null or Standard Stream Cipher // // Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6) @@ -310,18 +451,14 @@ static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size // } 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. // @@ -345,23 +482,26 @@ static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size // MD5 HMAC-MD5 16 16 // SHA HMAC-SHA1 20 20 // SHA256 HMAC-SHA256 32 32 - +static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size) +{ uint8_t mac_hash[SHA256_OUTSIZE]; struct record_hdr *xhdr = buf; if (tls->encrypt_on_write) { +//TODO: convert hmac_sha256 to precomputed hmac_sha256(mac_hash, tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key), &tls->write_seq64_be, sizeof(tls->write_seq64_be), buf, size, NULL); tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be)); + /* Temporarily change for writing */ xhdr->len16_lo += SHA256_OUTSIZE; -//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ FIXME } xwrite(tls->fd, buf, size); dbg("wrote %u bytes\n", size); + if (tls->encrypt_on_write) { xwrite(tls->fd, mac_hash, sizeof(mac_hash)); dbg("wrote %u bytes of hash\n", (int)sizeof(mac_hash)); @@ -374,12 +514,6 @@ static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size } } -static void tls_error_die(tls_state_t *tls) -{ - dump_tls_record(tls->inbuf, tls->insize + tls->tail); - xfunc_die(); -} - static int xread_tls_block(tls_state_t *tls) { struct record_hdr *xhdr; @@ -417,7 +551,7 @@ static int xread_tls_block(tls_state_t *tls) target -= sizeof(*xhdr); /* RFC 5246 is not saying it explicitly, but sha256 hash - * in our FINISHED packet must include hashes of incoming packets too! + * 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 + 5, target); @@ -427,23 +561,9 @@ static int xread_tls_block(tls_state_t *tls) return target; } -static int xread_tls_handshake_block(tls_state_t *tls, int min_len) -{ - struct record_hdr *xhdr; - int len = xread_tls_block(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; -} - +/* + * DER parsing routines + */ static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end) { unsigned len, len1; @@ -653,147 +773,26 @@ static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len) dbg("server_rsa_pub_key.size:%d\n", tls->server_rsa_pub_key.size); } -// 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_<hash>(secret, label + seed) -// -// The label is an ASCII string. -static void tls_prf_hmac_sha256( - uint8_t *outbuf, unsigned outbuf_size, - uint8_t *secret, unsigned secret_size, - const char *label, - uint8_t *seed, unsigned seed_size) +/* + * TLS Handshake routines + */ +static int xread_tls_handshake_block(tls_state_t *tls, int min_len) { - 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 + struct record_hdr *xhdr; + int len = xread_tls_block(tls); - 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); + 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); } -#undef A -#undef SECRET -#undef SEED + dbg("got HANDSHAKE\n"); + return len; } -/* - * TLS Handshake routines - */ static void send_client_hello(tls_state_t *tls) { struct client_hello { @@ -1055,7 +1054,7 @@ static void send_change_cipher_spec(tls_state_t *tls) dbg(">> CHANGE_CIPHER_SPEC\n"); xwrite(tls->fd, rec, sizeof(rec)); - tls->write_seq64_be = 0; + /* tls->write_seq64_be = 0; - already is */ tls->encrypt_on_write = 1; } |