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Revise hash management for reading the Finished message.

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Upstream originally sampled the Finished message's hash at ChangeCipherSpec,
but our patches to add messages between the two complicated this. Move DTLS to
this path, but use the new SSL_GET_MESSAGE_DONT_HASH_MESSAGE flag to avoid
special-casing message types in ssl3_get_message.

Change-Id: I9c8ddd9cc500c94dff2ec2f696f89d50ab01b3ad
Reviewed-on: https://boringssl-review.googlesource.com/1632
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2014-08-25 23:28:44 -04:00 committed by Adam Langley
parent 880b14e98c
commit 5b8f104ee8
2 changed files with 5 additions and 41 deletions
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21
ssl/s3_both.c
View File

@ -191,7 +191,6 @@ int ssl3_send_finished(SSL *s, int a, int b, const char *sender, int slen)
return ssl_do_write(s); return ssl_do_write(s);
} }
#ifndef OPENSSL_NO_NEXTPROTONEG
/* ssl3_take_mac calculates the Finished MAC for the handshakes messages seen to far. */ /* ssl3_take_mac calculates the Finished MAC for the handshakes messages seen to far. */
static void ssl3_take_mac(SSL *s) static void ssl3_take_mac(SSL *s)
{ {
@ -216,7 +215,6 @@ static void ssl3_take_mac(SSL *s)
s->s3->tmp.peer_finish_md_len = s->method->ssl3_enc->final_finish_mac(s, s->s3->tmp.peer_finish_md_len = s->method->ssl3_enc->final_finish_mac(s,
sender,slen,s->s3->tmp.peer_finish_md); sender,slen,s->s3->tmp.peer_finish_md);
} }
#endif
int ssl3_get_finished(SSL *s, int a, int b) int ssl3_get_finished(SSL *s, int a, int b)
{ {
@ -224,22 +222,20 @@ int ssl3_get_finished(SSL *s, int a, int b)
long n; long n;
unsigned char *p; unsigned char *p;
#ifdef OPENSSL_NO_NEXTPROTONEG
/* the mac has already been generated when we received the
* change cipher spec message and is in s->s3->tmp.peer_finish_md
*/
#endif
n=s->method->ssl_get_message(s, n=s->method->ssl_get_message(s,
a, a,
b, b,
SSL3_MT_FINISHED, SSL3_MT_FINISHED,
64, /* should actually be 36+4 :-) */ 64, /* should actually be 36+4 :-) */
SSL_GET_MESSAGE_HASH_MESSAGE, SSL_GET_MESSAGE_DONT_HASH_MESSAGE,
&ok); &ok);
if (!ok) return((int)n); if (!ok) return((int)n);
/* Snapshot the finished hash before incorporating the new message. */
ssl3_take_mac(s);
ssl3_hash_current_message(s);
/* If this occurs, we have missed a message. /* If this occurs, we have missed a message.
* TODO(davidben): Is this check now redundant with * TODO(davidben): Is this check now redundant with
* SSL3_FLAGS_EXPECT_CCS? */ * SSL3_FLAGS_EXPECT_CCS? */
@ -466,13 +462,6 @@ long ssl3_get_message(SSL *s, int st1, int stn, int mt, long max, int hash_messa
n -= i; n -= i;
} }
#ifndef OPENSSL_NO_NEXTPROTONEG
/* If receiving Finished, record MAC of prior handshake messages for
* Finished verification. */
if (*s->init_buf->data == SSL3_MT_FINISHED)
ssl3_take_mac(s);
#endif
/* Feed this message into MAC computation. */ /* Feed this message into MAC computation. */
if (hash_message != SSL_GET_MESSAGE_DONT_HASH_MESSAGE) if (hash_message != SSL_GET_MESSAGE_DONT_HASH_MESSAGE)
ssl3_hash_current_message(s); ssl3_hash_current_message(s);

25
ssl/s3_pkt.c
View File

@ -1426,8 +1426,6 @@ err:
int ssl3_do_change_cipher_spec(SSL *s) int ssl3_do_change_cipher_spec(SSL *s)
{ {
int i; int i;
const char *sender;
int slen;
if (s->state & SSL_ST_ACCEPT) if (s->state & SSL_ST_ACCEPT)
i=SSL3_CHANGE_CIPHER_SERVER_READ; i=SSL3_CHANGE_CIPHER_SERVER_READ;
@ -1450,29 +1448,6 @@ int ssl3_do_change_cipher_spec(SSL *s)
if (!s->method->ssl3_enc->change_cipher_state(s,i)) if (!s->method->ssl3_enc->change_cipher_state(s,i))
return(0); return(0);
/* we have to record the message digest at
* this point so we can get it before we read
* the finished message */
if (s->state & SSL_ST_CONNECT)
{
sender=s->method->ssl3_enc->server_finished_label;
slen=s->method->ssl3_enc->server_finished_label_len;
}
else
{
sender=s->method->ssl3_enc->client_finished_label;
slen=s->method->ssl3_enc->client_finished_label_len;
}
i = s->method->ssl3_enc->final_finish_mac(s,
sender,slen,s->s3->tmp.peer_finish_md);
if (i == 0)
{
OPENSSL_PUT_ERROR(SSL, ssl3_do_change_cipher_spec, ERR_R_INTERNAL_ERROR);
return 0;
}
s->s3->tmp.peer_finish_md_len = i;
return(1); return(1);
} }