From 90134d9806f0191bc0eb0cde2750f0cd68667a6d Mon Sep 17 00:00:00 2001 From: Benjamin Kaduk Date: Mon, 30 Jan 2017 19:20:14 -0600 Subject: [PATCH] Refactor SSL_bytes_to_cipher_list() Split off the portions that mutate the SSL object into a separate function that the state machine calls, so that the public API can be a pure function. (It still needs the SSL parameter in order to determine what SSL_METHOD's get_cipher_by_char() routine to use, though.) Instead of returning the stack of ciphers (functionality that was not used internally), require using the output parameter, and add a separate output parameter for the SCSVs contained in the supplied octets, if desired. This lets us move to the standard return value convention. Also make both output stacks optional parameters. Reviewed-by: Matt Caswell Reviewed-by: Richard Levitte (Merged from https://github.com/openssl/openssl/pull/2279) --- doc/man3/SSL_get_ciphers.pod | 19 ++--- include/openssl/ssl.h | 7 +- ssl/ssl_err.c | 1 + ssl/ssl_lib.c | 139 ++++++++++++++++++----------------- ssl/ssl_locl.h | 11 +-- ssl/statem/statem_srvr.c | 38 +++++++++- 6 files changed, 124 insertions(+), 91 deletions(-) diff --git a/doc/man3/SSL_get_ciphers.pod b/doc/man3/SSL_get_ciphers.pod index 5933bf5849..d1baafee79 100644 --- a/doc/man3/SSL_get_ciphers.pod +++ b/doc/man3/SSL_get_ciphers.pod @@ -15,9 +15,9 @@ SSL_bytes_to_cipher_list, SSL_get_cipher_list STACK_OF(SSL_CIPHER) *SSL_CTX_get_ciphers(const SSL_CTX *ctx); STACK_OF(SSL_CIPHER) *SSL_get1_supported_ciphers(SSL *s); STACK_OF(SSL_CIPHER) *SSL_get_client_ciphers(const SSL *ssl); - STACK_OF(SSL_CIPHER) *SSL_bytes_to_cipher_list(SSL *s, - const unsigned char *bytes, - size_t len, int isv2format) + int SSL_bytes_to_cipher_list(SSL *s, const unsigned char *bytes, size_t len, + int isv2format, STACK_OF(SSL_CIPHER) **sk, + STACK_OF(SSL_CIPHER) **scsvs); const char *SSL_get_cipher_list(const SSL *ssl, int priority); =head1 DESCRIPTION @@ -49,8 +49,9 @@ SSL_bytes_to_cipher_list() treats the supplied B octets in B as a wire-protocol cipher suite specification (in the three-octet-per-cipher SSLv2 wire format if B is nonzero; otherwise the two-octet SSLv3/TLS wire format), and parses the cipher suites supported by the library -into the returned stack of SSL_CIPHER objects. Unsupported cipher suites -are ignored, and NULL is returned on error. +into the returned stacks of SSL_CIPHER objects sk and Signalling Cipher-Suite +Values scsvs. Unsupported cipher suites are ignored. Returns 1 on success +and 0 on failure. SSL_get_cipher_list() returns a pointer to the name of the SSL_CIPHER listed for B with B. If B is NULL, no ciphers are @@ -74,19 +75,13 @@ free the return value itself. The stack returned by SSL_get1_supported_ciphers() should be freed using sk_SSL_CIPHER_free(). -The stack returned by SSL_bytes_to_cipher_list() should be freed using +The stacks returned by SSL_bytes_to_cipher_list() should be freed using sk_SSL_CIPHER_free(). =head1 RETURN VALUES See DESCRIPTION -=head1 BUGS - -The implementation of SSL_bytes_to_cipher_list() mutates state in the -supplied SSL object B; SSL_bytes_to_cipher_list() should not be called -on a server SSL object after that server has processed the received ClientHello. - =head1 SEE ALSO L, L, diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h index 3716922b42..cb4dbff327 100644 --- a/include/openssl/ssl.h +++ b/include/openssl/ssl.h @@ -1820,9 +1820,9 @@ __owur int SSL_COMP_add_compression_method(int id, COMP_METHOD *cm); const SSL_CIPHER *SSL_CIPHER_find(SSL *ssl, const unsigned char *ptr); int SSL_CIPHER_get_cipher_nid(const SSL_CIPHER *c); int SSL_CIPHER_get_digest_nid(const SSL_CIPHER *c); -STACK_OF(SSL_CIPHER) *SSL_bytes_to_cipher_list(SSL *s, - const unsigned char *bytes, - size_t len, int isv2format); +int SSL_bytes_to_cipher_list(SSL *s, const unsigned char *bytes, size_t len, + int isv2format, STACK_OF(SSL_CIPHER) **sk, + STACK_OF(SSL_CIPHER) **scsvs); /* TLS extensions functions */ __owur int SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len); @@ -2164,6 +2164,7 @@ int ERR_load_SSL_strings(void); # define SSL_F_SSL_BAD_METHOD 160 # define SSL_F_SSL_BUILD_CERT_CHAIN 332 # define SSL_F_SSL_BYTES_TO_CIPHER_LIST 161 +# define SSL_F_SSL_CACHE_CIPHERLIST 520 # define SSL_F_SSL_CERT_ADD0_CHAIN_CERT 346 # define SSL_F_SSL_CERT_DUP 221 # define SSL_F_SSL_CERT_NEW 162 diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c index 81b3a67852..d937ba2c6e 100644 --- a/ssl/ssl_err.c +++ b/ssl/ssl_err.c @@ -118,6 +118,7 @@ static ERR_STRING_DATA SSL_str_functs[] = { {ERR_FUNC(SSL_F_SSL_BAD_METHOD), "ssl_bad_method"}, {ERR_FUNC(SSL_F_SSL_BUILD_CERT_CHAIN), "ssl_build_cert_chain"}, {ERR_FUNC(SSL_F_SSL_BYTES_TO_CIPHER_LIST), "SSL_bytes_to_cipher_list"}, + {ERR_FUNC(SSL_F_SSL_CACHE_CIPHERLIST), "ssl_cache_cipherlist"}, {ERR_FUNC(SSL_F_SSL_CERT_ADD0_CHAIN_CERT), "ssl_cert_add0_chain_cert"}, {ERR_FUNC(SSL_F_SSL_CERT_DUP), "ssl_cert_dup"}, {ERR_FUNC(SSL_F_SSL_CERT_NEW), "ssl_cert_new"}, diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c index 56c6a2442c..ff99c0f707 100644 --- a/ssl/ssl_lib.c +++ b/ssl/ssl_lib.c @@ -4402,54 +4402,26 @@ int ssl_log_secret(SSL *ssl, secret_len); } - -STACK_OF(SSL_CIPHER) *SSL_bytes_to_cipher_list(SSL *s, - const unsigned char *bytes, - size_t len, int isv2format) -{ - int alert; - PACKET pkt; - - if (!PACKET_buf_init(&pkt, bytes, len)) - return 0; - return bytes_to_cipher_list(s, &pkt, NULL, isv2format, &alert); -} - #define SSLV2_CIPHER_LEN 3 -STACK_OF(SSL_CIPHER) *bytes_to_cipher_list(SSL *s, - PACKET *cipher_suites, - STACK_OF(SSL_CIPHER) **skp, - int sslv2format, int *al) +int ssl_cache_cipherlist(SSL *s, PACKET *cipher_suites, int sslv2format, + int *al) { - const SSL_CIPHER *c; - STACK_OF(SSL_CIPHER) *sk; int n; - /* 3 = SSLV2_CIPHER_LEN > TLS_CIPHER_LEN = 2. */ - unsigned char cipher[SSLV2_CIPHER_LEN]; - - s->s3->send_connection_binding = 0; n = sslv2format ? SSLV2_CIPHER_LEN : TLS_CIPHER_LEN; if (PACKET_remaining(cipher_suites) == 0) { - SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, SSL_R_NO_CIPHERS_SPECIFIED); + SSLerr(SSL_F_SSL_CACHE_CIPHERLIST, SSL_R_NO_CIPHERS_SPECIFIED); *al = SSL_AD_ILLEGAL_PARAMETER; - return NULL; + return 0; } if (PACKET_remaining(cipher_suites) % n != 0) { - SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, + SSLerr(SSL_F_SSL_CACHE_CIPHERLIST, SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST); *al = SSL_AD_DECODE_ERROR; - return NULL; - } - - sk = sk_SSL_CIPHER_new_null(); - if (sk == NULL) { - SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, ERR_R_MALLOC_FAILURE); - *al = SSL_AD_INTERNAL_ERROR; - return NULL; + return 0; } OPENSSL_free(s->s3->tmp.ciphers_raw); @@ -4498,6 +4470,57 @@ STACK_OF(SSL_CIPHER) *bytes_to_cipher_list(SSL *s, *al = SSL_AD_INTERNAL_ERROR; goto err; } + return 1; + err: + return 0; +} + +int SSL_bytes_to_cipher_list(SSL *s, const unsigned char *bytes, size_t len, + int isv2format, STACK_OF(SSL_CIPHER) **sk, + STACK_OF(SSL_CIPHER) **scsvs) +{ + int alert; + PACKET pkt; + + if (!PACKET_buf_init(&pkt, bytes, len)) + return 0; + return bytes_to_cipher_list(s, &pkt, sk, scsvs, isv2format, &alert); +} + +int bytes_to_cipher_list(SSL *s, PACKET *cipher_suites, + STACK_OF(SSL_CIPHER) **skp, + STACK_OF(SSL_CIPHER) **scsvs_out, + int sslv2format, int *al) +{ + const SSL_CIPHER *c; + STACK_OF(SSL_CIPHER) *sk = NULL; + STACK_OF(SSL_CIPHER) *scsvs = NULL; + int n; + /* 3 = SSLV2_CIPHER_LEN > TLS_CIPHER_LEN = 2. */ + unsigned char cipher[SSLV2_CIPHER_LEN]; + + n = sslv2format ? SSLV2_CIPHER_LEN : TLS_CIPHER_LEN; + + if (PACKET_remaining(cipher_suites) == 0) { + SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, SSL_R_NO_CIPHERS_SPECIFIED); + *al = SSL_AD_ILLEGAL_PARAMETER; + return 0; + } + + if (PACKET_remaining(cipher_suites) % n != 0) { + SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, + SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST); + *al = SSL_AD_DECODE_ERROR; + return 0; + } + + sk = sk_SSL_CIPHER_new_null(); + scsvs = sk_SSL_CIPHER_new_null(); + if (sk == NULL || scsvs == NULL) { + SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, ERR_R_MALLOC_FAILURE); + *al = SSL_AD_INTERNAL_ERROR; + goto err; + } while (PACKET_copy_bytes(cipher_suites, cipher, n)) { /* @@ -4508,41 +4531,11 @@ STACK_OF(SSL_CIPHER) *bytes_to_cipher_list(SSL *s, if (sslv2format && cipher[0] != '\0') continue; - /* Check for TLS_EMPTY_RENEGOTIATION_INFO_SCSV */ - if ((cipher[n - 2] == ((SSL3_CK_SCSV >> 8) & 0xff)) && - (cipher[n - 1] == (SSL3_CK_SCSV & 0xff))) { - /* SCSV fatal if renegotiating */ - if (s->renegotiate) { - SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, - SSL_R_SCSV_RECEIVED_WHEN_RENEGOTIATING); - *al = SSL_AD_HANDSHAKE_FAILURE; - goto err; - } - s->s3->send_connection_binding = 1; - continue; - } - - /* Check for TLS_FALLBACK_SCSV */ - if ((cipher[n - 2] == ((SSL3_CK_FALLBACK_SCSV >> 8) & 0xff)) && - (cipher[n - 1] == (SSL3_CK_FALLBACK_SCSV & 0xff))) { - /* - * The SCSV indicates that the client previously tried a higher - * version. Fail if the current version is an unexpected - * downgrade. - */ - if (!ssl_check_version_downgrade(s)) { - SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, - SSL_R_INAPPROPRIATE_FALLBACK); - *al = SSL_AD_INAPPROPRIATE_FALLBACK; - goto err; - } - continue; - } - /* For SSLv2-compat, ignore leading 0-byte. */ c = ssl_get_cipher_by_char(s, sslv2format ? &cipher[1] : cipher, 1); if (c != NULL) { - if (!sk_SSL_CIPHER_push(sk, c)) { + if ((c->valid && !sk_SSL_CIPHER_push(sk, c)) || + (!c->valid && !sk_SSL_CIPHER_push(scsvs, c))) { SSLerr(SSL_F_BYTES_TO_CIPHER_LIST, ERR_R_MALLOC_FAILURE); *al = SSL_AD_INTERNAL_ERROR; goto err; @@ -4555,9 +4548,17 @@ STACK_OF(SSL_CIPHER) *bytes_to_cipher_list(SSL *s, goto err; } - *skp = sk; - return sk; + if (skp != NULL) + *skp = sk; + else + sk_SSL_CIPHER_free(sk); + if (scsvs_out != NULL) + *scsvs_out = scsvs; + else + sk_SSL_CIPHER_free(scsvs); + return 1; err: sk_SSL_CIPHER_free(sk); - return NULL; + sk_SSL_CIPHER_free(scsvs); + return 0; } diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h index 59605f5983..40bcdd26f2 100644 --- a/ssl/ssl_locl.h +++ b/ssl/ssl_locl.h @@ -1991,11 +1991,12 @@ __owur STACK_OF(SSL_CIPHER) *ssl_create_cipher_list(const SSL_METHOD *meth, **sorted, const char *rule_str, CERT *c); -__owur STACK_OF(SSL_CIPHER) *bytes_to_cipher_list(SSL *s, - PACKET *cipher_suites, - STACK_OF(SSL_CIPHER) - **skp, int sslv2format, - int *al); +__owur int ssl_cache_cipherlist(SSL *s, PACKET *cipher_suites, + int sslv2format, int *al); +__owur int bytes_to_cipher_list(SSL *s, PACKET *cipher_suites, + STACK_OF(SSL_CIPHER) **skp, + STACK_OF(SSL_CIPHER) **scsvs, int sslv2format, + int *al); void ssl_update_cache(SSL *s, int mode); __owur int ssl_cipher_get_evp(const SSL_SESSION *s, const EVP_CIPHER **enc, const EVP_MD **md, int *mac_pkey_type, diff --git a/ssl/statem/statem_srvr.c b/ssl/statem/statem_srvr.c index 00e69a671e..880996b126 100644 --- a/ssl/statem/statem_srvr.c +++ b/ssl/statem/statem_srvr.c @@ -1226,6 +1226,7 @@ MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt) SSL_COMP *comp = NULL; #endif STACK_OF(SSL_CIPHER) *ciphers = NULL; + STACK_OF(SSL_CIPHER) *scsvs = NULL; int protverr; /* |cookie| will only be initialized for DTLS. */ PACKET session_id, compression, extensions, cookie; @@ -1546,11 +1547,44 @@ MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt) } } - if (bytes_to_cipher_list(s, &clienthello.ciphersuites, &ciphers, - clienthello.isv2, &al) == NULL) { + if (!ssl_cache_cipherlist(s, &clienthello.ciphersuites, + clienthello.isv2, &al) || + !bytes_to_cipher_list(s, &clienthello.ciphersuites, &ciphers, &scsvs, + clienthello.isv2, &al)) { goto f_err; } + s->s3->send_connection_binding = 0; + /* Check what signalling cipher-suite values were received. */ + if (scsvs != NULL) { + for(i = 0; i < sk_SSL_CIPHER_num(scsvs); i++) { + c = sk_SSL_CIPHER_value(scsvs, i); + if (SSL_CIPHER_get_id(c) == SSL3_CK_SCSV) { + if (s->renegotiate) { + /* SCSV is fatal if renegotiating */ + SSLerr(SSL_F_TLS_PROCESS_CLIENT_HELLO, + SSL_R_SCSV_RECEIVED_WHEN_RENEGOTIATING); + al = SSL_AD_HANDSHAKE_FAILURE; + goto f_err; + } + s->s3->send_connection_binding = 1; + } else if (SSL_CIPHER_get_id(c) == SSL3_CK_FALLBACK_SCSV && + !ssl_check_version_downgrade(s)) { + /* + * This SCSV indicates that the client previously tried + * a higher version. We should fail if the current version + * is an unexpected downgrade, as that indicates that the first + * connection may have been tampered with in order to trigger + * an insecure downgrade. + */ + SSLerr(SSL_F_TLS_PROCESS_CLIENT_HELLO, + SSL_R_INAPPROPRIATE_FALLBACK); + al = SSL_AD_INAPPROPRIATE_FALLBACK; + goto f_err; + } + } + } + /* If it is a hit, check that the cipher is in the list */ if (s->hit) { j = 0; -- 2.25.1