From 0aed6e449da5f06a23fd191bb86bfdd71bde6f9c Mon Sep 17 00:00:00 2001 From: Benjamin Kaduk Date: Tue, 1 Aug 2017 15:28:14 -0500 Subject: [PATCH] Add SSL_get_pending_cipher() The existing function SSL_get_current_cipher() queries the current session for the ciphersuite in use, but there is no way for application code to determine what ciphersuite has been negotiated and will be used in the future, prior to ChangeCipherState (or the TLS 1.3 equivalent) causing the new cipher to take effect and become visible in the session information. Expose this information to appropriate application callbacks to use during the handshake. The name SSL_get_pending_cipher() was chosen for compatibility with BoringSSL's routine of that name. Improve the note on macro implementations in SSL_get_current_cipher.pod while here. Reviewed-by: Matt Caswell (Merged from https://github.com/openssl/openssl/pull/4070) --- doc/man3/SSL_get_current_cipher.pod | 20 ++++++++++++++++++-- include/openssl/ssl.h | 1 + ssl/ssl_lib.c | 5 +++++ util/libssl.num | 1 + 4 files changed, 25 insertions(+), 2 deletions(-) diff --git a/doc/man3/SSL_get_current_cipher.pod b/doc/man3/SSL_get_current_cipher.pod index cb7e9994a7..e5b249fd1e 100644 --- a/doc/man3/SSL_get_current_cipher.pod +++ b/doc/man3/SSL_get_current_cipher.pod @@ -3,13 +3,15 @@ =head1 NAME SSL_get_current_cipher, SSL_get_cipher_name, SSL_get_cipher, -SSL_get_cipher_bits, SSL_get_cipher_version - get SSL_CIPHER of a connection +SSL_get_cipher_bits, SSL_get_cipher_version, +SSL_get_pending_cipher - get SSL_CIPHER of a connection =head1 SYNOPSIS #include SSL_CIPHER *SSL_get_current_cipher(const SSL *ssl); + SSL_CIPHER *SSL_get_pending_cipher(const SSL *ssl); const char *SSL_get_cipher_name(const SSL *s); const char *SSL_get_cipher(const SSL *s); @@ -30,14 +32,28 @@ SSL_get_cipher_bits() is a macro to obtain the number of secret/algorithm bits used and SSL_get_cipher_version() returns the protocol name. +SSL_get_pending_cipher() returns a pointer to an SSL_CIPHER object containing +the description of the cipher (if any) that has been negotiated for future use +on the connection established with the B object, but is not yet in use. +This may be the case during handshake processing, when control flow can be +returned to the application via any of several callback methods. The internal +sequencing of handshake processing and callback invocation is not guaranteed +to be stable from release to release, and at present only the callback set +by SSL_CTX_set_alpn_select_cb() is guaranteed to have a non-NULL return value. +Other callbacks may be added to this list over time. + =head1 RETURN VALUES SSL_get_current_cipher() returns the cipher actually used, or NULL if no session has been established. +SSL_get_pending_cipher() returns the cipher to be used at the next change +of cipher suite, or NULL if no such cipher is known. + =head1 NOTES -These are implemented as macros. +SSL_get_cipher, SSL_get_cipher_bits, SSL_get_cipher_version, and +SSL_get_cipher_name are implemented as macros. =head1 SEE ALSO diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h index b4c66441c2..04388817b6 100644 --- a/include/openssl/ssl.h +++ b/include/openssl/ssl.h @@ -1430,6 +1430,7 @@ __owur int SSL_clear(SSL *s); void SSL_CTX_flush_sessions(SSL_CTX *ctx, long tm); __owur const SSL_CIPHER *SSL_get_current_cipher(const SSL *s); +__owur const SSL_CIPHER *SSL_get_pending_cipher(const SSL *s); __owur int SSL_CIPHER_get_bits(const SSL_CIPHER *c, int *alg_bits); __owur const char *SSL_CIPHER_get_version(const SSL_CIPHER *c); __owur const char *SSL_CIPHER_get_name(const SSL_CIPHER *c); diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c index 3abb27140b..ed2113caa5 100644 --- a/ssl/ssl_lib.c +++ b/ssl/ssl_lib.c @@ -3613,6 +3613,11 @@ const SSL_CIPHER *SSL_get_current_cipher(const SSL *s) return (NULL); } +const SSL_CIPHER *SSL_get_pending_cipher(const SSL *s) +{ + return s->s3->tmp.new_cipher; +} + const COMP_METHOD *SSL_get_current_compression(SSL *s) { #ifndef OPENSSL_NO_COMP diff --git a/util/libssl.num b/util/libssl.num index 78fb65a685..7d4c01e80f 100644 --- a/util/libssl.num +++ b/util/libssl.num @@ -463,3 +463,4 @@ OPENSSL_cipher_name 463 1_1_1 EXIST::FUNCTION: SSL_alloc_buffers 464 1_1_1 EXIST::FUNCTION: SSL_free_buffers 465 1_1_1 EXIST::FUNCTION: SSL_SESSION_dup 466 1_1_1 EXIST::FUNCTION: +SSL_get_pending_cipher 467 1_1_1 EXIST::FUNCTION: -- 2.25.1