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tls: if !ENABLE_FEATURE_TLS_SHA1, tls->MAC_size is always SHA256_OUTSIZE for AES-CBC

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function                                             old     new   delta
tls_xread_record                                     634     636      +2
xwrite_encrypted                                     579     580      +1
tls_handshake                                       2095    2085     -10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 3/-10)              Total: -7 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-12-10 16:43:53 +01:00
parent 71fa5b0a4c
commit 63bfe0e4c0
1 changed files with 12 additions and 6 deletions
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18
networking/tls.c
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@ -407,6 +407,12 @@ static void hash_handshake(tls_state_t *tls, const char *fmt, const void *buffer
#endif
}
#if !ENABLE_FEATURE_TLS_SHA1
# define TLS_MAC_SIZE(tls) SHA256_OUTSIZE
#else
# define TLS_MAC_SIZE(tls) (tls)->MAC_size
#endif
// RFC 2104:
// HMAC(key, text) based on a hash H (say, sha256) is:
// ipad = [0x36 x INSIZE]
@ -691,7 +697,7 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
/* Calculate MAC signature */
hmac(tls, buf + size, /* result */
tls->client_write_MAC_key, tls->MAC_size,
tls->client_write_MAC_key, TLS_MAC_SIZE(tls),
&tls->write_seq64_be, sizeof(tls->write_seq64_be),
xhdr, RECHDR_LEN,
buf, size,
@ -699,7 +705,7 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
);
tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
size += tls->MAC_size;
size += TLS_MAC_SIZE(tls);
// RFC 5246:
// 6.2.3.1. Null or Standard Stream Cipher
@ -784,7 +790,7 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
tls_get_random(buf - AES_BLOCK_SIZE, AES_BLOCK_SIZE); /* IV */
dbg("before crypt: 5 hdr + %u data + %u hash bytes\n",
size - tls->MAC_size, tls->MAC_size);
size - TLS_MAC_SIZE(tls), TLS_MAC_SIZE(tls));
/* Fill IV and padding in outbuf */
// RFC is talking nonsense:
@ -1099,7 +1105,7 @@ static int tls_xread_record(tls_state_t *tls, const char *expected)
tls_aesgcm_decrypt(tls, p, sz);
dbg("encrypted size:%u\n", sz);
} else
if (tls->min_encrypted_len_on_read > tls->MAC_size) {
if (tls->min_encrypted_len_on_read > TLS_MAC_SIZE(tls)) {
/* AES+SHA */
uint8_t *p = tls->inbuf + RECHDR_LEN;
int padding_len;
@ -1118,7 +1124,7 @@ static int tls_xread_record(tls_state_t *tls, const char *expected)
padding_len = p[sz - 1];
dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[0], padding_len);
padding_len++;
sz -= tls->MAC_size + padding_len; /* drop MAC and padding */
sz -= TLS_MAC_SIZE(tls) + padding_len; /* drop MAC and padding */
} else {
/* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
/* else: no encryption yet on input, subtract zero = NOP */
@ -2245,7 +2251,7 @@ void FAST_FUNC tls_handshake(tls_state_t *tls, const char *sni)
tls->min_encrypted_len_on_read = tls->MAC_size;
} else
if (!(tls->flags & ENCRYPTION_AESGCM)) {
unsigned mac_blocks = (unsigned)(tls->MAC_size + AES_BLOCK_SIZE-1) / AES_BLOCK_SIZE;
unsigned mac_blocks = (unsigned)(TLS_MAC_SIZE(tls) + AES_BLOCK_SIZE-1) / AES_BLOCK_SIZE;
/* all incoming packets now should be encrypted and have
* at least IV + (MAC padded to blocksize):
*/