From 59dcfa21e5aa551f6a53f35ee5244e2e23e0183a Mon Sep 17 00:00:00 2001 From: Bodo Moeller Date: Wed, 15 Oct 2014 04:05:57 +0200 Subject: [PATCH] Support TLS_FALLBACK_SCSV. Reviewed-by: Rich Salz --- CHANGES | 6 +++++ apps/s_client.c | 10 ++++++++ crypto/err/openssl.ec | 1 + ssl/d1_lib.c | 10 ++++++++ ssl/dtls1.h | 3 ++- ssl/s23_clnt.c | 3 +++ ssl/s23_srvr.c | 3 +++ ssl/s2_lib.c | 4 ++- ssl/s3_enc.c | 2 +- ssl/s3_lib.c | 25 +++++++++++++++++- ssl/ssl.h | 9 +++++++ ssl/ssl3.h | 7 ++++- ssl/ssl_err.c | 2 ++ ssl/ssl_lib.c | 60 +++++++++++++++++++++++++++++++++---------- ssl/t1_enc.c | 1 + ssl/tls1.h | 20 ++++++++++----- 16 files changed, 141 insertions(+), 25 deletions(-) diff --git a/CHANGES b/CHANGES index ecb0b416b3..21446c5dc1 100644 --- a/CHANGES +++ b/CHANGES @@ -4,6 +4,12 @@ Changes between 1.0.0n and 1.0.0o [xx XXX xxxx] + *) Add support for TLS_FALLBACK_SCSV. + Client applications doing fallback retries should call + SSL_set_mode(s, SSL_MODE_SEND_FALLBACK_SCSV). + (CVE-2014-3566) + [Adam Langley, Bodo Moeller] + *) Add additional DigestInfo checks. Reencode DigestInto in DER and check against the original when diff --git a/apps/s_client.c b/apps/s_client.c index a24951dc96..a75cfcf7ee 100644 --- a/apps/s_client.c +++ b/apps/s_client.c @@ -322,6 +322,7 @@ static void sc_usage(void) BIO_printf(bio_err," -ssl3 - just use SSLv3\n"); BIO_printf(bio_err," -tls1 - just use TLSv1\n"); BIO_printf(bio_err," -dtls1 - just use DTLSv1\n"); + BIO_printf(bio_err," -fallback_scsv - send TLS_FALLBACK_SCSV\n"); BIO_printf(bio_err," -mtu - set the link layer MTU\n"); BIO_printf(bio_err," -no_tls1/-no_ssl3/-no_ssl2 - turn off that protocol\n"); BIO_printf(bio_err," -bugs - Switch on all SSL implementation bug workarounds\n"); @@ -436,6 +437,7 @@ int MAIN(int argc, char **argv) char *sess_out = NULL; struct sockaddr peer; int peerlen = sizeof(peer); + int fallback_scsv = 0; int enable_timeouts = 0 ; long socket_mtu = 0; #ifndef OPENSSL_NO_JPAKE @@ -602,6 +604,10 @@ int MAIN(int argc, char **argv) meth=DTLSv1_client_method(); socket_type=SOCK_DGRAM; } + else if (strcmp(*argv,"-fallback_scsv") == 0) + { + fallback_scsv = 1; + } else if (strcmp(*argv,"-timeout") == 0) enable_timeouts=1; else if (strcmp(*argv,"-mtu") == 0) @@ -935,6 +941,10 @@ bad: SSL_set_session(con, sess); SSL_SESSION_free(sess); } + + if (fallback_scsv) + SSL_set_mode(con, SSL_MODE_SEND_FALLBACK_SCSV); + #ifndef OPENSSL_NO_TLSEXT if (servername != NULL) { diff --git a/crypto/err/openssl.ec b/crypto/err/openssl.ec index e0554b4342..34754e553d 100644 --- a/crypto/err/openssl.ec +++ b/crypto/err/openssl.ec @@ -71,6 +71,7 @@ R SSL_R_TLSV1_ALERT_EXPORT_RESTRICTION 1060 R SSL_R_TLSV1_ALERT_PROTOCOL_VERSION 1070 R SSL_R_TLSV1_ALERT_INSUFFICIENT_SECURITY 1071 R SSL_R_TLSV1_ALERT_INTERNAL_ERROR 1080 +R SSL_R_SSLV3_ALERT_INAPPROPRIATE_FALLBACK 1086 R SSL_R_TLSV1_ALERT_USER_CANCELLED 1090 R SSL_R_TLSV1_ALERT_NO_RENEGOTIATION 1100 R SSL_R_TLSV1_UNSUPPORTED_EXTENSION 1110 diff --git a/ssl/d1_lib.c b/ssl/d1_lib.c index ebee36840e..83db13e571 100644 --- a/ssl/d1_lib.c +++ b/ssl/d1_lib.c @@ -265,6 +265,16 @@ long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg) case DTLS_CTRL_LISTEN: ret = dtls1_listen(s, parg); break; + case SSL_CTRL_CHECK_PROTO_VERSION: + /* For library-internal use; checks that the current protocol + * is the highest enabled version (according to s->ctx->method, + * as version negotiation may have changed s->method). */ +#if DTLS_MAX_VERSION != DTLS1_VERSION +# error Code needs update for DTLS_method() support beyond DTLS1_VERSION. +#endif + /* Just one protocol version is supported so far; + * fail closed if the version is not as expected. */ + return s->version == DTLS_MAX_VERSION; default: ret = ssl3_ctrl(s, cmd, larg, parg); diff --git a/ssl/dtls1.h b/ssl/dtls1.h index 2900d1d8ae..3e5578dd0e 100644 --- a/ssl/dtls1.h +++ b/ssl/dtls1.h @@ -80,6 +80,8 @@ extern "C" { #endif #define DTLS1_VERSION 0xFEFF +#define DTLS_MAX_VERSION DTLS1_VERSION + #define DTLS1_BAD_VER 0x0100 #if 0 @@ -264,4 +266,3 @@ typedef struct dtls1_record_data_st } #endif #endif - diff --git a/ssl/s23_clnt.c b/ssl/s23_clnt.c index c4d8bf2eb3..4183a02d32 100644 --- a/ssl/s23_clnt.c +++ b/ssl/s23_clnt.c @@ -632,6 +632,9 @@ static int ssl23_get_server_hello(SSL *s) goto err; } + /* ensure that TLS_MAX_VERSION is up-to-date */ + OPENSSL_assert(s->version <= TLS_MAX_VERSION); + if (p[0] == SSL3_RT_ALERT && p[5] != SSL3_AL_WARNING) { /* fatal alert */ diff --git a/ssl/s23_srvr.c b/ssl/s23_srvr.c index a997bb5d60..9a88cef15c 100644 --- a/ssl/s23_srvr.c +++ b/ssl/s23_srvr.c @@ -389,6 +389,9 @@ int ssl23_get_client_hello(SSL *s) } } + /* ensure that TLS_MAX_VERSION is up-to-date */ + OPENSSL_assert(s->version <= TLS_MAX_VERSION); + if (s->state == SSL23_ST_SR_CLNT_HELLO_B) { /* we have SSLv3/TLSv1 in an SSLv2 header diff --git a/ssl/s2_lib.c b/ssl/s2_lib.c index c0bdae5496..c63be3052b 100644 --- a/ssl/s2_lib.c +++ b/ssl/s2_lib.c @@ -391,6 +391,8 @@ long ssl2_ctrl(SSL *s, int cmd, long larg, void *parg) case SSL_CTRL_GET_SESSION_REUSED: ret=s->hit; break; + case SSL_CTRL_CHECK_PROTO_VERSION: + return ssl3_ctrl(s, SSL_CTRL_CHECK_PROTO_VERSION, larg, parg); default: break; } @@ -437,7 +439,7 @@ int ssl2_put_cipher_by_char(const SSL_CIPHER *c, unsigned char *p) if (p != NULL) { l=c->id; - if ((l & 0xff000000) != 0x02000000) return(0); + if ((l & 0xff000000) != 0x02000000 && l != SSL3_CK_FALLBACK_SCSV) return(0); p[0]=((unsigned char)(l>>16L))&0xFF; p[1]=((unsigned char)(l>> 8L))&0xFF; p[2]=((unsigned char)(l ))&0xFF; diff --git a/ssl/s3_enc.c b/ssl/s3_enc.c index c44cc9298a..9a494f3063 100644 --- a/ssl/s3_enc.c +++ b/ssl/s3_enc.c @@ -888,7 +888,7 @@ int ssl3_alert_code(int code) case SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE: return(SSL3_AD_HANDSHAKE_FAILURE); case SSL_AD_BAD_CERTIFICATE_HASH_VALUE: return(SSL3_AD_HANDSHAKE_FAILURE); case SSL_AD_UNKNOWN_PSK_IDENTITY:return(TLS1_AD_UNKNOWN_PSK_IDENTITY); + case SSL_AD_INAPPROPRIATE_FALLBACK:return(TLS1_AD_INAPPROPRIATE_FALLBACK); default: return(-1); } } - diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c index 577ffd5291..b874dd473f 100644 --- a/ssl/s3_lib.c +++ b/ssl/s3_lib.c @@ -2492,6 +2492,29 @@ long ssl3_ctrl(SSL *s, int cmd, long larg, void *parg) break; #endif /* !OPENSSL_NO_TLSEXT */ + + case SSL_CTRL_CHECK_PROTO_VERSION: + /* For library-internal use; checks that the current protocol + * is the highest enabled version (according to s->ctx->method, + * as version negotiation may have changed s->method). */ + if (s->version == s->ctx->method->version) + return 1; + /* Apparently we're using a version-flexible SSL_METHOD + * (not at its highest protocol version). */ + if (s->ctx->method->version == SSLv23_method()->version) + { +#if TLS_MAX_VERSION != TLS1_VERSION +# error Code needs update for SSLv23_method() support beyond TLS1_VERSION. +#endif + if (!(s->options & SSL_OP_NO_TLSv1)) + return s->version == TLS1_VERSION; + if (!(s->options & SSL_OP_NO_SSLv3)) + return s->version == SSL3_VERSION; + if (!(s->options & SSL_OP_NO_SSLv2)) + return s->version == SSL2_VERSION; + } + return 0; /* Unexpected state; fail closed. */ + default: break; } @@ -2793,6 +2816,7 @@ long ssl3_ctx_callback_ctrl(SSL_CTX *ctx, int cmd, void (*fp)(void)) break; #endif + default: return(0); } @@ -3347,4 +3371,3 @@ need to go to SSL_ST_ACCEPT. } return(ret); } - diff --git a/ssl/ssl.h b/ssl/ssl.h index 235c7b20af..70aff9dcc3 100644 --- a/ssl/ssl.h +++ b/ssl/ssl.h @@ -605,6 +605,10 @@ typedef struct ssl_session_st * TLS only.) "Released" buffers are put onto a free-list in the context * or just freed (depending on the context's setting for freelist_max_len). */ #define SSL_MODE_RELEASE_BUFFERS 0x00000010L +/* Send TLS_FALLBACK_SCSV in the ClientHello. + * To be set by applications that reconnect with a downgraded protocol + * version; see draft-ietf-tls-downgrade-scsv-00 for details. */ +#define SSL_MODE_SEND_FALLBACK_SCSV 0x00000080L /* Note: SSL[_CTX]_set_{options,mode} use |= op on the previous value, * they cannot be used to clear bits. */ @@ -1328,6 +1332,7 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION) #define SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE TLS1_AD_BAD_CERTIFICATE_STATUS_RESPONSE #define SSL_AD_BAD_CERTIFICATE_HASH_VALUE TLS1_AD_BAD_CERTIFICATE_HASH_VALUE #define SSL_AD_UNKNOWN_PSK_IDENTITY TLS1_AD_UNKNOWN_PSK_IDENTITY /* fatal */ +#define SSL_AD_INAPPROPRIATE_FALLBACK TLS1_AD_INAPPROPRIATE_FALLBACK /* fatal */ #define SSL_ERROR_NONE 0 #define SSL_ERROR_SSL 1 @@ -1421,6 +1426,8 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION) #define SSL_CTRL_CLEAR_OPTIONS 77 #define SSL_CTRL_CLEAR_MODE 78 +#define SSL_CTRL_CHECK_PROTO_VERSION 119 + #define DTLSv1_get_timeout(ssl, arg) \ SSL_ctrl(ssl,DTLS_CTRL_GET_TIMEOUT,0, (void *)arg) #define DTLSv1_handle_timeout(ssl) \ @@ -2106,6 +2113,7 @@ void ERR_load_SSL_strings(void); #define SSL_R_HTTPS_PROXY_REQUEST 155 #define SSL_R_HTTP_REQUEST 156 #define SSL_R_ILLEGAL_PADDING 283 +#define SSL_R_INAPPROPRIATE_FALLBACK 373 #define SSL_R_INCONSISTENT_COMPRESSION 340 #define SSL_R_INVALID_CHALLENGE_LENGTH 158 #define SSL_R_INVALID_COMMAND 280 @@ -2244,6 +2252,7 @@ void ERR_load_SSL_strings(void); #define SSL_R_TLSV1_ALERT_DECRYPTION_FAILED 1021 #define SSL_R_TLSV1_ALERT_DECRYPT_ERROR 1051 #define SSL_R_TLSV1_ALERT_EXPORT_RESTRICTION 1060 +#define SSL_R_TLSV1_ALERT_INAPPROPRIATE_FALLBACK 1086 #define SSL_R_TLSV1_ALERT_INSUFFICIENT_SECURITY 1071 #define SSL_R_TLSV1_ALERT_INTERNAL_ERROR 1080 #define SSL_R_TLSV1_ALERT_NO_RENEGOTIATION 1100 diff --git a/ssl/ssl3.h b/ssl/ssl3.h index 9664a8b145..263d16dcbd 100644 --- a/ssl/ssl3.h +++ b/ssl/ssl3.h @@ -128,9 +128,14 @@ extern "C" { #endif -/* Signalling cipher suite value: from draft-ietf-tls-renegotiation-03.txt */ +/* Signalling cipher suite value from RFC 5746 + * (TLS_EMPTY_RENEGOTIATION_INFO_SCSV) */ #define SSL3_CK_SCSV 0x030000FF +/* Signalling cipher suite value from draft-ietf-tls-downgrade-scsv-00 + * (TLS_FALLBACK_SCSV) */ +#define SSL3_CK_FALLBACK_SCSV 0x03005600 + #define SSL3_CK_RSA_NULL_MD5 0x03000001 #define SSL3_CK_RSA_NULL_SHA 0x03000002 #define SSL3_CK_RSA_RC4_40_MD5 0x03000003 diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c index 32d9af1fcb..65cd51648d 100644 --- a/ssl/ssl_err.c +++ b/ssl/ssl_err.c @@ -361,6 +361,7 @@ static ERR_STRING_DATA SSL_str_reasons[]= {ERR_REASON(SSL_R_HTTPS_PROXY_REQUEST) ,"https proxy request"}, {ERR_REASON(SSL_R_HTTP_REQUEST) ,"http request"}, {ERR_REASON(SSL_R_ILLEGAL_PADDING) ,"illegal padding"}, +{ERR_REASON(SSL_R_INAPPROPRIATE_FALLBACK),"inappropriate fallback"}, {ERR_REASON(SSL_R_INCONSISTENT_COMPRESSION),"inconsistent compression"}, {ERR_REASON(SSL_R_INVALID_CHALLENGE_LENGTH),"invalid challenge length"}, {ERR_REASON(SSL_R_INVALID_COMMAND) ,"invalid command"}, @@ -499,6 +500,7 @@ static ERR_STRING_DATA SSL_str_reasons[]= {ERR_REASON(SSL_R_TLSV1_ALERT_DECRYPTION_FAILED),"tlsv1 alert decryption failed"}, {ERR_REASON(SSL_R_TLSV1_ALERT_DECRYPT_ERROR),"tlsv1 alert decrypt error"}, {ERR_REASON(SSL_R_TLSV1_ALERT_EXPORT_RESTRICTION),"tlsv1 alert export restriction"}, +{ERR_REASON(SSL_R_TLSV1_ALERT_INAPPROPRIATE_FALLBACK),"tlsv1 alert inappropriate fallback"}, {ERR_REASON(SSL_R_TLSV1_ALERT_INSUFFICIENT_SECURITY),"tlsv1 alert insufficient security"}, {ERR_REASON(SSL_R_TLSV1_ALERT_INTERNAL_ERROR),"tlsv1 alert internal error"}, {ERR_REASON(SSL_R_TLSV1_ALERT_NO_RENEGOTIATION),"tlsv1 alert no renegotiation"}, diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c index caf7554447..f45b3628dd 100644 --- a/ssl/ssl_lib.c +++ b/ssl/ssl_lib.c @@ -1360,6 +1360,8 @@ int ssl_cipher_list_to_bytes(SSL *s,STACK_OF(SSL_CIPHER) *sk,unsigned char *p, if (sk == NULL) return(0); q=p; + if (put_cb == NULL) + put_cb = s->method->put_cipher_by_char; for (i=0; ipsk_client_callback == NULL) continue; #endif /* OPENSSL_NO_PSK */ - j = put_cb ? put_cb(c,p) : ssl_put_cipher_by_char(s,c,p); + j = put_cb(c,p); p+=j; } - /* If p == q, no ciphers and caller indicates an error. Otherwise - * add SCSV if not renegotiating. - */ - if (p != q && !s->new_session) + /* If p == q, no ciphers; caller indicates an error. + * Otherwise, add applicable SCSVs. */ + if (p != q) { - static SSL_CIPHER scsv = + if (!s->new_session) { - 0, NULL, SSL3_CK_SCSV, 0, 0, 0, 0, 0, 0, 0, 0, 0 - }; - j = put_cb ? put_cb(&scsv,p) : ssl_put_cipher_by_char(s,&scsv,p); - p+=j; + static SSL_CIPHER scsv = + { + 0, NULL, SSL3_CK_SCSV, 0, 0, 0, 0, 0, 0, 0, 0, 0 + }; + j = put_cb(&scsv,p); + p+=j; #ifdef OPENSSL_RI_DEBUG - fprintf(stderr, "SCSV sent by client\n"); + fprintf(stderr, "TLS_EMPTY_RENEGOTIATION_INFO_SCSV sent by client\n"); #endif - } + } + + if (s->mode & SSL_MODE_SEND_FALLBACK_SCSV) + { + static SSL_CIPHER scsv = + { + 0, NULL, SSL3_CK_FALLBACK_SCSV, 0, 0, 0, 0, 0, 0, 0, 0, 0 + }; + j = put_cb(&scsv,p); + p+=j; + } + } return(p-q); } @@ -1403,11 +1417,12 @@ STACK_OF(SSL_CIPHER) *ssl_bytes_to_cipher_list(SSL *s,unsigned char *p,int num, const SSL_CIPHER *c; STACK_OF(SSL_CIPHER) *sk; int i,n; + if (s->s3) s->s3->send_connection_binding = 0; n=ssl_put_cipher_by_char(s,NULL,NULL); - if ((num%n) != 0) + if (n == 0 || (num%n) != 0) { SSLerr(SSL_F_SSL_BYTES_TO_CIPHER_LIST,SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST); return(NULL); @@ -1422,7 +1437,7 @@ STACK_OF(SSL_CIPHER) *ssl_bytes_to_cipher_list(SSL *s,unsigned char *p,int num, for (i=0; is3 && (n != 3 || !p[0]) && (p[n-2] == ((SSL3_CK_SCSV >> 8) & 0xff)) && (p[n-1] == (SSL3_CK_SCSV & 0xff))) @@ -1442,6 +1457,23 @@ STACK_OF(SSL_CIPHER) *ssl_bytes_to_cipher_list(SSL *s,unsigned char *p,int num, continue; } + /* Check for TLS_FALLBACK_SCSV */ + if ((n != 3 || !p[0]) && + (p[n-2] == ((SSL3_CK_FALLBACK_SCSV >> 8) & 0xff)) && + (p[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_ctrl(s, SSL_CTRL_CHECK_PROTO_VERSION, 0, NULL)) + { + SSLerr(SSL_F_SSL_BYTES_TO_CIPHER_LIST,SSL_R_INAPPROPRIATE_FALLBACK); + if (s->s3) + ssl3_send_alert(s,SSL3_AL_FATAL,SSL_AD_INAPPROPRIATE_FALLBACK); + goto err; + } + continue; + } + c=ssl_get_cipher_by_char(s,p); p+=n; if (c != NULL) diff --git a/ssl/t1_enc.c b/ssl/t1_enc.c index a5410ce529..7220a85db3 100644 --- a/ssl/t1_enc.c +++ b/ssl/t1_enc.c @@ -1035,6 +1035,7 @@ int tls1_alert_code(int code) case SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE: return(TLS1_AD_BAD_CERTIFICATE_STATUS_RESPONSE); case SSL_AD_BAD_CERTIFICATE_HASH_VALUE: return(TLS1_AD_BAD_CERTIFICATE_HASH_VALUE); case SSL_AD_UNKNOWN_PSK_IDENTITY:return(TLS1_AD_UNKNOWN_PSK_IDENTITY); + case SSL_AD_INAPPROPRIATE_FALLBACK:return(TLS1_AD_INAPPROPRIATE_FALLBACK); #if 0 /* not appropriate for TLS, not used for DTLS */ case DTLS1_AD_MISSING_HANDSHAKE_MESSAGE: return (DTLS1_AD_MISSING_HANDSHAKE_MESSAGE); diff --git a/ssl/tls1.h b/ssl/tls1.h index 1be58fadc2..47014dc893 100644 --- a/ssl/tls1.h +++ b/ssl/tls1.h @@ -159,17 +159,24 @@ extern "C" { #define TLS1_ALLOW_EXPERIMENTAL_CIPHERSUITES 0 +#define TLS1_VERSION 0x0301 +#define TLS1_1_VERSION 0x0302 #define TLS1_2_VERSION 0x0303 -#define TLS1_2_VERSION_MAJOR 0x03 -#define TLS1_2_VERSION_MINOR 0x03 +/* TLS 1.1 and 1.2 are not supported by this version of TLS, so + * TLS_MAX_VERSION indicates TLS 1.0 regardless of the above + * definitions. (s23_clnt.c and s23_srvr.c have an OPENSSL_assert() + * check that would catch the error if TLS_MAX_VERSION was too low.) + */ +#define TLS_MAX_VERSION TLS1_VERSION + +#define TLS1_VERSION_MAJOR 0x03 +#define TLS1_VERSION_MINOR 0x01 -#define TLS1_1_VERSION 0x0302 #define TLS1_1_VERSION_MAJOR 0x03 #define TLS1_1_VERSION_MINOR 0x02 -#define TLS1_VERSION 0x0301 -#define TLS1_VERSION_MAJOR 0x03 -#define TLS1_VERSION_MINOR 0x01 +#define TLS1_2_VERSION_MAJOR 0x03 +#define TLS1_2_VERSION_MINOR 0x03 #define TLS1_get_version(s) \ ((s->version >> 8) == TLS1_VERSION_MAJOR ? s->version : 0) @@ -187,6 +194,7 @@ extern "C" { #define TLS1_AD_PROTOCOL_VERSION 70 /* fatal */ #define TLS1_AD_INSUFFICIENT_SECURITY 71 /* fatal */ #define TLS1_AD_INTERNAL_ERROR 80 /* fatal */ +#define TLS1_AD_INAPPROPRIATE_FALLBACK 86 /* fatal */ #define TLS1_AD_USER_CANCELLED 90 #define TLS1_AD_NO_RENEGOTIATION 100 /* codes 110-114 are from RFC3546 */ -- 2.25.1