56fa8e69cf
From: "Chris D. Peterson" <cpeterson@aventail.com> Subject: Implementation Issues with OpenSSL To: openssl-users@openssl.org Date: Wed, 22 Aug 2001 16:13:17 -0700 The patch included in the original post may improve the internal session list handling (and is therefore worth a seperate investigation). No change to the list handling will however solve the problems of incorrect SSL_SESSION_free() calls. The session list is only one possible point of failure, dangling pointers would also occur for SSL object currently using the session. The correct solution is to only use SSL_SESSION_free() when applicable!
55 lines
2.1 KiB
Text
55 lines
2.1 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
SSL_SESSION_free - free an allocated SSL_SESSION structure
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/ssl.h>
|
|
|
|
void SSL_SESSION_free(SSL_SESSION *session);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
SSL_SESSION_free() decrements the reference count of B<session> and removes
|
|
the B<SSL_SESSION> structure pointed to by B<session> and frees up the allocated
|
|
memory, if the the reference count has reached 0.
|
|
|
|
=head1 NOTES
|
|
|
|
SSL_SESSION objects are allocated, when a TLS/SSL handshake operation
|
|
is successfully completed. Depending on the settings, see
|
|
L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
|
|
the SSL_SESSION objects are internally referenced by the SSL_CTX and
|
|
linked into its session cache. SSL objects may be using the SSL_SESSION object;
|
|
as a session may be reused, several SSL objects may be using one SSL_SESSION
|
|
object at the same time. It is therefore crucial to keep the reference
|
|
count (usage information) correct and not delete a SSL_SESSION object
|
|
that is still used, as this may lead to program failures due to
|
|
dangling pointers. These failures may also appear delayed, e.g.
|
|
when an SSL_SESSION object was completely freed as the reference count
|
|
incorrectly became 0, but it is still referenced in the internal
|
|
session cache and the cache list is processed during a
|
|
L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)> operation.
|
|
|
|
SSL_SESSION_free() must only be called for SSL_SESSION objects, for
|
|
which the reference count was explicitly incremented (e.g.
|
|
by calling SSL_get1_session(), see L<SSL_get_session(3)|SSL_get_session(3)>)
|
|
or when the SSL_SESSION object was generated outside a TLS handshake
|
|
operation, e.g. by using L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>.
|
|
It must not be called on other SSL_SESSION objects, as this would cause
|
|
incorrect reference counts and therefore program failures.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
SSL_SESSION_free() does not provide diagnostic information.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ssl(3)|ssl(3)>, L<SSL_get_session(3)|SSL_get_session(3)>,
|
|
L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
|
|
L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>,
|
|
L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>
|
|
|
|
=cut
|