diff options
author | Rob Stradling <rob@comodo.com> | 2013-09-09 10:44:29 +0100 |
---|---|---|
committer | Ben Laurie <ben@links.org> | 2013-09-16 14:03:21 +0100 |
commit | 07df5018befd637a2a02ebd767969aa953200b3f (patch) | |
tree | 9a2d95619c872122ffca125fd9f98c85535293ff /ssl/t1_lib.c | |
parent | 1b9a59c36a547443dbefb0faed6598b3a15719c9 (diff) |
Don't prefer ECDHE-ECDSA ciphers when the client appears to be Safari on OS X.
OS X 10.8..10.8.3 has broken support for ECDHE-ECDSA ciphers.
Diffstat (limited to 'ssl/t1_lib.c')
-rw-r--r-- | ssl/t1_lib.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 10f094fcd5..1992b918b3 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -1762,6 +1762,89 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned cha return ret; } +#ifndef OPENSSL_NO_EC +/* ssl_check_for_safari attempts to fingerprint Safari using OS X + * SecureTransport using the TLS extension block in |d|, of length |n|. + * Safari, since 10.6, sends exactly these extensions, in this order: + * SNI, + * elliptic_curves + * ec_point_formats + * + * We wish to fingerprint Safari because they broke ECDHE-ECDSA support in 10.8, + * but they advertise support. So enabling ECDHE-ECDSA ciphers breaks them. + * Sadly we cannot differentiate 10.6, 10.7 and 10.8.4 (which work), from + * 10.8..10.8.3 (which don't work). + */ +static void ssl_check_for_safari(SSL *s, const unsigned char *data, const unsigned char *d, int n) { + unsigned short type, size; + static const unsigned char kSafariExtensionsBlock[] = { + 0x00, 0x0a, /* elliptic_curves extension */ + 0x00, 0x08, /* 8 bytes */ + 0x00, 0x06, /* 6 bytes of curve ids */ + 0x00, 0x17, /* P-256 */ + 0x00, 0x18, /* P-384 */ + 0x00, 0x19, /* P-521 */ + + 0x00, 0x0b, /* ec_point_formats */ + 0x00, 0x02, /* 2 bytes */ + 0x01, /* 1 point format */ + 0x00, /* uncompressed */ + }; + + /* The following is only present in TLS 1.2 */ + static const unsigned char kSafariTLS12ExtensionsBlock[] = { + 0x00, 0x0d, /* signature_algorithms */ + 0x00, 0x0c, /* 12 bytes */ + 0x00, 0x0a, /* 10 bytes */ + 0x05, 0x01, /* SHA-384/RSA */ + 0x04, 0x01, /* SHA-256/RSA */ + 0x02, 0x01, /* SHA-1/RSA */ + 0x04, 0x03, /* SHA-256/ECDSA */ + 0x02, 0x03, /* SHA-1/ECDSA */ + }; + + if (data >= (d+n-2)) + return; + data += 2; + + if (data > (d+n-4)) + return; + n2s(data,type); + n2s(data,size); + + if (type != TLSEXT_TYPE_server_name) + return; + + if (data+size > d+n) + return; + data += size; + + if (TLS1_get_version(s) >= TLS1_2_VERSION) + { + const size_t len1 = sizeof(kSafariExtensionsBlock); + const size_t len2 = sizeof(kSafariTLS12ExtensionsBlock); + + if (data + len1 + len2 != d+n) + return; + if (memcmp(data, kSafariExtensionsBlock, len1) != 0) + return; + if (memcmp(data + len1, kSafariTLS12ExtensionsBlock, len2) != 0) + return; + } + else + { + const size_t len = sizeof(kSafariExtensionsBlock); + + if (data + len != d+n) + return; + if (memcmp(data, kSafariExtensionsBlock, len) != 0) + return; + } + + s->s3->is_probably_safari = 1; +} +#endif /* OPENSSL_NO_EC */ + static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, int n, int *al) { unsigned short type; @@ -1781,6 +1864,12 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED | SSL_TLSEXT_HB_DONT_SEND_REQUESTS); #endif + +#ifndef OPENSSL_NO_EC + if (s->options & SSL_OP_SAFARI_ECDHE_ECDSA_BUG) + ssl_check_for_safari(s, data, d, n); +#endif /* OPENSSL_NO_EC */ + /* Clear any signature algorithms extension received */ if (s->cert->peer_sigalgs) { |