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author | Dirkjan Bussink <d.bussink@gmail.com> | 2014-04-23 17:27:10 -0700 |
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committer | Andreas Schneider <asn@cryptomilk.org> | 2019-02-22 18:21:25 +0100 |
commit | 8892577296dba23fdd531d222e66b208b60f12c4 (patch) | |
tree | 2573d40a06ef00495e7ec11aa21d3c64e050df8a | |
parent | ac7c64a76915fa35287782ee9da685d2f59cabea (diff) | |
download | libssh-8892577296dba23fdd531d222e66b208b60f12c4.tar.gz libssh-8892577296dba23fdd531d222e66b208b60f12c4.tar.xz libssh-8892577296dba23fdd531d222e66b208b60f12c4.zip |
Use constant time comparison function for HMAC comparison
Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>
Reviewed-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
(cherry picked from commit 46d15b316103587e5c185d2af69e906477c35a8b)
-rw-r--r-- | src/packet_crypt.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/src/packet_crypt.c b/src/packet_crypt.c index 7306e4b3..ba1d4af9 100644 --- a/src/packet_crypt.c +++ b/src/packet_crypt.c @@ -176,6 +176,17 @@ unsigned char *ssh_packet_encrypt(ssh_session session, void *data, uint32_t len) return session->current_crypto->hmacbuf; } +static int secure_memcmp(const void *s1, const void *s2, size_t n) +{ + int rc = 0; + const unsigned char *p1 = s1; + const unsigned char *p2 = s2; + for (; n > 0; --n) { + rc |= *p1++ ^ *p2++; + } + return (rc != 0); +} + /** * @internal * @@ -219,7 +230,7 @@ int ssh_packet_hmac_verify(ssh_session session, ssh_print_hexa("Computed mac",hmacbuf,len); ssh_print_hexa("seq",(unsigned char *)&seq,sizeof(uint32_t)); #endif - if (memcmp(mac, hmacbuf, len) == 0) { + if (secure_memcmp(mac, hmacbuf, len) == 0) { return 0; } |