diff options
| -rw-r--r-- | networking/tls.c | 256 | ||||
| -rw-r--r-- | networking/tls.h | 2 | ||||
| -rw-r--r-- | networking/tls_rsa.c | 2 |
3 files changed, 225 insertions, 35 deletions
diff --git a/networking/tls.c b/networking/tls.c index 44c9da1..9bc75f8 100644 --- a/networking/tls.c +++ b/networking/tls.c @@ -146,6 +146,11 @@ typedef struct tls_state { 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]; + // RFC 5246 // |6.2.1. Fragmentation // | The record layer fragments information blocks into TLSPlaintext @@ -187,9 +192,18 @@ 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 xwrite_and_hash(tls_state_t *tls, const void *buf, unsigned size) +{ + xwrite(tls->fd, buf, size); + /* hash does not include record headers */ + if (size > 5) + sha256_hash(&tls->handshake_sha256_ctx, (uint8_t*)buf + 5, size - 5); +} + static unsigned get24be(const uint8_t *p) { return 0x100*(0x100*p[0] + p[1]) + p[2]; @@ -494,6 +508,156 @@ 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); } +enum { + SHA256_INSIZE = 64, + SHA256_OUTSIZE = 32, +}; + +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); +} + +// 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); + + 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 +} + /* * TLS Handshake routines */ @@ -535,7 +699,9 @@ static void send_client_hello(tls_state_t *tls) hello.comprtypes_len = 1; //hello.comprtypes[0] = 0; - xwrite(tls->fd, &hello, sizeof(hello)); + xwrite_and_hash(tls, &hello, sizeof(hello)); + memcpy(tls->client_and_server_rand32, hello.rand32, sizeof(hello.rand32)); + #if 0 /* dump */ for (;;) { uint8_t buf[16*1024]; @@ -589,6 +755,7 @@ static void get_server_hello(tls_state_t *tls) tls_error_die(tls); } dbg("got SERVER_HELLO\n"); + memcpy(tls->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32)); } static void get_server_cert(tls_state_t *tls) @@ -665,7 +832,23 @@ static void send_client_key_exchange(tls_state_t *tls) data_param_ignored ); - xwrite(tls->fd, &record, sizeof(record)); + xwrite_and_hash(tls, &record, sizeof(record)); + +// 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. + tls_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) + ); } static void send_change_cipher_spec(tls_state_t *tls) @@ -674,42 +857,12 @@ static void send_change_cipher_spec(tls_state_t *tls) RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01, 01 }; + /* Not "xwrite_and_hash": this is not a handshake message */ xwrite(tls->fd, rec, sizeof(rec)); } static void send_client_finished(tls_state_t *tls) { -// RFC 5246 on pseudorandom function (PRF): -// -// 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(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. - - tls->fd = 0; - // 7.4.9. Finished // A Finished message is always sent immediately after a change // cipher spec message to verify that the key exchange and @@ -747,6 +900,39 @@ static void send_client_finished(tls_state_t *tls) // 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. + struct client_finished { + struct record_hdr xhdr; + uint8_t type; + uint8_t len24_hi, len24_mid, len24_lo; + uint8_t prf_result[12]; + }; + struct client_finished record; + uint8_t handshake_hash[SHA256_OUTSIZE]; + sha256_ctx_t ctx; + + memset(&record, 0, sizeof(record)); + record.xhdr.type = RECORD_TYPE_HANDSHAKE; + record.xhdr.proto_maj = TLS_MAJ; + record.xhdr.proto_min = TLS_MIN; + record.xhdr.len16_hi = (sizeof(record) - sizeof(record.xhdr)) >> 8; + record.xhdr.len16_lo = (sizeof(record) - sizeof(record.xhdr)) & 0xff; + record.type = HANDSHAKE_FINISHED; + //record.len24_hi = 0; + record.len24_mid = (sizeof(record) - sizeof(record.xhdr) - 4) >> 8; + record.len24_lo = (sizeof(record) - sizeof(record.xhdr) - 4) & 0xff; +//FIXME ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code is repeatable + + ctx = tls->handshake_sha256_ctx; /* struct copy */ + sha256_end(&ctx, handshake_hash); + tls_prf_hmac_sha256(record.prf_result, sizeof(record.prf_result), + tls->master_secret, sizeof(tls->master_secret), + "client finished", + handshake_hash, sizeof(handshake_hash) + ); + +//(1) TODO: well, this should be encrypted on send, really. +//(2) do we really need to also hash it? + xwrite_and_hash(tls, &record, sizeof(record)); } static void get_change_cipher_spec(tls_state_t *tls) @@ -831,6 +1017,10 @@ static void tls_handshake(tls_state_t *tls) } } +// To run a test server using openssl: +// openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 +// openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost' + int tls_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int tls_main(int argc UNUSED_PARAM, char **argv) { diff --git a/networking/tls.h b/networking/tls.h index 20317ec..3a8a3d8 100644 --- a/networking/tls.h +++ b/networking/tls.h @@ -59,7 +59,7 @@ void tls_get_random(void *buf, unsigned len); #define matrixCryptoGetPrngData(buf, len, userPtr) (tls_get_random(buf, len), PS_SUCCESS) #define psFree(p, pool) free(p) -#define psTraceCrypto(msg) bb_error_msg_and_die(msg) +#define psTraceCrypto(...) bb_error_msg_and_die(__VA_ARGS__) /* Secure zerofill */ #define memset_s(A,B,C,D) memset((A),(C),(D)) diff --git a/networking/tls_rsa.c b/networking/tls_rsa.c index 3114435..df71186 100644 --- a/networking/tls_rsa.c +++ b/networking/tls_rsa.c @@ -187,7 +187,7 @@ int32 psRsaEncryptPub(psPool_t *pool, psRsaKey_t *key, size = key->size; if (outlen < size) { - psTraceCrypto("Error on bad outlen parameter to psRsaEncryptPub\n"); + psTraceCrypto("Error on bad outlen parameter to psRsaEncryptPub: outlen:%d < size:%d", outlen, size); return PS_ARG_FAIL; } |