From 98ece4eebfb6cd45cc8d550c6ac0022965071afc Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Mon, 18 May 2015 16:27:48 +0100 Subject: [PATCH] Fix race condition in NewSessionTicket If a NewSessionTicket is received by a multi-threaded client when attempting to reuse a previous ticket then a race condition can occur potentially leading to a double free of the ticket data. CVE-2015-1791 This also fixes RT#3808 where a session ID is changed for a session already in the client session cache. Since the session ID is the key to the cache this breaks the cache access. Parts of this patch were inspired by this Akamai change: https://github.com/akamai/openssl/commit/c0bf69a791239ceec64509f9f19fcafb2461b0d3 Reviewed-by: Rich Salz --- include/openssl/ssl.h | 1 + ssl/s3_clnt.c | 32 ++++++++++++ ssl/ssl_err.c | 1 + ssl/ssl_locl.h | 1 + ssl/ssl_sess.c | 116 ++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 151 insertions(+) diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h index 3e2dac6746..4e18b65605 100644 --- a/include/openssl/ssl.h +++ b/include/openssl/ssl.h @@ -2048,6 +2048,7 @@ void ERR_load_SSL_strings(void); # define SSL_F_SSL_READ 223 # define SSL_F_SSL_SCAN_CLIENTHELLO_TLSEXT 320 # define SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT 321 +# define SSL_F_SSL_SESSION_DUP 348 # define SSL_F_SSL_SESSION_NEW 189 # define SSL_F_SSL_SESSION_PRINT_FP 190 # define SSL_F_SSL_SESSION_SET1_ID_CONTEXT 312 diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c index f70dce4b0d..d6f53b0dea 100644 --- a/ssl/s3_clnt.c +++ b/ssl/s3_clnt.c @@ -2238,6 +2238,38 @@ int ssl3_get_new_session_ticket(SSL *s) } p = d = (unsigned char *)s->init_msg; + + if (s->session->session_id_length > 0) { + int i = s->session_ctx->session_cache_mode; + SSL_SESSION *new_sess; + /* + * We reused an existing session, so we need to replace it with a new + * one + */ + if (i & SSL_SESS_CACHE_CLIENT) { + /* + * Remove the old session from the cache + */ + if (i & SSL_SESS_CACHE_NO_INTERNAL_STORE) { + if (s->session_ctx->remove_session_cb != NULL) + s->session_ctx->remove_session_cb(s->session_ctx, + s->session); + } else { + /* We carry on if this fails */ + SSL_CTX_remove_session(s->session_ctx, s->session); + } + } + + if ((new_sess = ssl_session_dup(s->session, 0)) == 0) { + al = SSL_AD_INTERNAL_ERROR; + SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, ERR_R_MALLOC_FAILURE); + goto f_err; + } + + SSL_SESSION_free(s->session); + s->session = new_sess; + } + n2l(p, s->session->tlsext_tick_lifetime_hint); n2s(p, ticklen); /* ticket_lifetime_hint + ticket_length + ticket */ diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c index 86f8fa891a..4b4d89ce7a 100644 --- a/ssl/ssl_err.c +++ b/ssl/ssl_err.c @@ -274,6 +274,7 @@ static ERR_STRING_DATA SSL_str_functs[] = { "SSL_SCAN_CLIENTHELLO_TLSEXT"}, {ERR_FUNC(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT), "SSL_SCAN_SERVERHELLO_TLSEXT"}, + {ERR_FUNC(SSL_F_SSL_SESSION_DUP), "ssl_session_dup"}, {ERR_FUNC(SSL_F_SSL_SESSION_NEW), "SSL_SESSION_new"}, {ERR_FUNC(SSL_F_SSL_SESSION_PRINT_FP), "SSL_SESSION_print_fp"}, {ERR_FUNC(SSL_F_SSL_SESSION_SET1_ID_CONTEXT), diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h index 9d1f80ab8f..3252631e1c 100644 --- a/ssl/ssl_locl.h +++ b/ssl/ssl_locl.h @@ -1860,6 +1860,7 @@ __owur int ssl_set_peer_cert_type(SESS_CERT *c, int type); __owur int ssl_get_new_session(SSL *s, int session); __owur int ssl_get_prev_session(SSL *s, unsigned char *session, int len, const unsigned char *limit); +__owur SSL_SESSION *ssl_session_dup(SSL_SESSION *src, int ticket); __owur int ssl_cipher_id_cmp(const SSL_CIPHER *a, const SSL_CIPHER *b); DECLARE_OBJ_BSEARCH_GLOBAL_CMP_FN(SSL_CIPHER, SSL_CIPHER, ssl_cipher_id); __owur int ssl_cipher_ptr_id_cmp(const SSL_CIPHER *const *ap, diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c index f1c209508c..fd940541d5 100644 --- a/ssl/ssl_sess.c +++ b/ssl/ssl_sess.c @@ -225,6 +225,122 @@ SSL_SESSION *SSL_SESSION_new(void) return (ss); } +/* + * Create a new SSL_SESSION and duplicate the contents of |src| into it. If + * ticket == 0 then no ticket information is duplicated, otherwise it is. + */ +SSL_SESSION *ssl_session_dup(SSL_SESSION *src, int ticket) +{ + SSL_SESSION *dest; + + dest = OPENSSL_malloc(sizeof(*src)); + if (dest == NULL) { + goto err; + } + memcpy(dest, src, sizeof(*dest)); + +#ifndef OPENSSL_NO_PSK + if (src->psk_identity_hint) { + dest->psk_identity_hint = BUF_strdup(src->psk_identity_hint); + if (dest->psk_identity_hint == NULL) { + goto err; + } + } else { + dest->psk_identity_hint = NULL; + } + if (src->psk_identity) { + dest->psk_identity = BUF_strdup(src->psk_identity); + if (dest->psk_identity == NULL) { + goto err; + } + } else { + dest->psk_identity = NULL; + } +#endif + + if (src->sess_cert != NULL) + CRYPTO_add(&src->sess_cert->references, 1, CRYPTO_LOCK_SSL_SESS_CERT); + + if (src->peer != NULL) + CRYPTO_add(&src->peer->references, 1, CRYPTO_LOCK_X509); + + dest->references = 1; + + if(src->ciphers != NULL) { + dest->ciphers = sk_SSL_CIPHER_dup(src->ciphers); + if (dest->ciphers == NULL) + goto err; + } else { + dest->ciphers = NULL; + } + + if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, + &dest->ex_data, &src->ex_data)) { + goto err; + } + + /* We deliberately don't copy the prev and next pointers */ + dest->prev = NULL; + dest->next = NULL; + +#ifndef OPENSSL_NO_TLSEXT + if (src->tlsext_hostname) { + dest->tlsext_hostname = BUF_strdup(src->tlsext_hostname); + if (dest->tlsext_hostname == NULL) { + goto err; + } + } else { + dest->tlsext_hostname = NULL; + } +# ifndef OPENSSL_NO_EC + if (src->tlsext_ecpointformatlist) { + dest->tlsext_ecpointformatlist = + BUF_memdup(src->tlsext_ecpointformatlist, + src->tlsext_ecpointformatlist_length); + if (dest->tlsext_ecpointformatlist == NULL) + goto err; + dest->tlsext_ecpointformatlist_length = + src->tlsext_ecpointformatlist_length; + } + if (src->tlsext_ellipticcurvelist) { + dest->tlsext_ellipticcurvelist = + BUF_memdup(src->tlsext_ellipticcurvelist, + src->tlsext_ellipticcurvelist_length); + if (dest->tlsext_ellipticcurvelist == NULL) + goto err; + dest->tlsext_ellipticcurvelist_length = + src->tlsext_ellipticcurvelist_length; + } +# endif +#endif + + if (ticket != 0) { + dest->tlsext_tick_lifetime_hint = src->tlsext_tick_lifetime_hint; + dest->tlsext_ticklen = src->tlsext_ticklen; + if((dest->tlsext_tick = OPENSSL_malloc(src->tlsext_ticklen)) == NULL) { + goto err; + } + } + +#ifndef OPENSSL_NO_SRP + dest->srp_username = NULL; + if (src->srp_username) { + dest->srp_username = BUF_strdup(src->srp_username); + if (dest->srp_username == NULL) { + goto err; + } + } else { + dest->srp_username = NULL; + } +#endif + + return dest; +err: + SSLerr(SSL_F_SSL_SESSION_DUP, ERR_R_MALLOC_FAILURE); + SSL_SESSION_free(dest); + return NULL; +} + const unsigned char *SSL_SESSION_get_id(const SSL_SESSION *s, unsigned int *len) { -- 2.34.1