diff options
author | Benjamin Kaduk <bkaduk@akamai.com> | 2020-01-24 13:44:27 -0800 |
---|---|---|
committer | Benjamin Kaduk <kaduk@mit.edu> | 2020-03-13 16:11:45 -0700 |
commit | 44bad9cbf7daa5ff7dd201e0c61e684b2e2eb971 (patch) | |
tree | 7566571c3c79cf9b78b08a2a59362e178759e651 | |
parent | 910c8ffaf83a498667c10a28580dc18cbfd643c5 (diff) |
Code to thread-safety in ChangeCipherState
The server-side ChangeCipherState processing stores the new cipher
in the SSL_SESSION object, so that the new state can be used if
this session gets resumed. However, writing to the session is only
thread-safe for initial handshakes, as at other times the session
object may be in a shared cache and in use by another thread at the
same time. Reflect this invariant in the code by only writing to
s->session->cipher when it is currently NULL (we do not cache sessions
with no cipher). The code prior to this change would never actually
change the (non-NULL) cipher value in a session object, since our
server enforces that (pre-TLS-1.3) resumptions use the exact same
cipher as the initial connection, and non-abbreviated renegotiations
have produced a new session object before we get to this point.
Regardless, include logic to detect such a condition and abort the
handshake if it occurs, to avoid any risk of inadvertently using
the wrong cipher on a connection.
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/10943)
(cherry picked from commit 2e3ec2e1578977fca830a47fd7f521e290540e6d)
-rw-r--r-- | crypto/err/openssl.txt | 1 | ||||
-rw-r--r-- | include/openssl/sslerr.h | 1 | ||||
-rw-r--r-- | ssl/statem/statem_srvr.c | 10 |
3 files changed, 11 insertions, 1 deletions
diff --git a/crypto/err/openssl.txt b/crypto/err/openssl.txt index 10444a17f9..f5324c6819 100644 --- a/crypto/err/openssl.txt +++ b/crypto/err/openssl.txt @@ -1180,6 +1180,7 @@ SSL_F_OSSL_STATEM_SERVER_CONSTRUCT_MESSAGE:431:* SSL_F_OSSL_STATEM_SERVER_POST_PROCESS_MESSAGE:601:\ ossl_statem_server_post_process_message SSL_F_OSSL_STATEM_SERVER_POST_WORK:602:ossl_statem_server_post_work +SSL_F_OSSL_STATEM_SERVER_PRE_WORK:640: SSL_F_OSSL_STATEM_SERVER_PROCESS_MESSAGE:603:ossl_statem_server_process_message SSL_F_OSSL_STATEM_SERVER_READ_TRANSITION:418:ossl_statem_server_read_transition SSL_F_OSSL_STATEM_SERVER_WRITE_TRANSITION:604:\ diff --git a/include/openssl/sslerr.h b/include/openssl/sslerr.h index b6cac4f5f5..0ef684f3c1 100644 --- a/include/openssl/sslerr.h +++ b/include/openssl/sslerr.h @@ -88,6 +88,7 @@ int ERR_load_SSL_strings(void); # define SSL_F_OSSL_STATEM_SERVER_CONSTRUCT_MESSAGE 431 # define SSL_F_OSSL_STATEM_SERVER_POST_PROCESS_MESSAGE 601 # define SSL_F_OSSL_STATEM_SERVER_POST_WORK 602 +# define SSL_F_OSSL_STATEM_SERVER_PRE_WORK 640 # define SSL_F_OSSL_STATEM_SERVER_PROCESS_MESSAGE 603 # define SSL_F_OSSL_STATEM_SERVER_READ_TRANSITION 418 # define SSL_F_OSSL_STATEM_SERVER_WRITE_TRANSITION 604 diff --git a/ssl/statem/statem_srvr.c b/ssl/statem/statem_srvr.c index e055cc2f3a..75619d9bca 100644 --- a/ssl/statem/statem_srvr.c +++ b/ssl/statem/statem_srvr.c @@ -743,7 +743,15 @@ WORK_STATE ossl_statem_server_pre_work(SSL *s, WORK_STATE wst) case TLS_ST_SW_CHANGE: if (SSL_IS_TLS13(s)) break; - s->session->cipher = s->s3->tmp.new_cipher; + /* Writes to s->session are only safe for initial handshakes */ + if (s->session->cipher == NULL) { + s->session->cipher = s->s3->tmp.new_cipher; + } else if (s->session->cipher != s->s3->tmp.new_cipher) { + SSLfatal(s, SSL_AD_INTERNAL_ERROR, + SSL_F_OSSL_STATEM_SERVER_PRE_WORK, + ERR_R_INTERNAL_ERROR); + return WORK_ERROR; + } if (!s->method->ssl3_enc->setup_key_block(s)) { /* SSLfatal() already called */ return WORK_ERROR; |