dovecot-1.2: SSL: Enable SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS flag...

[dovecot at dovecot.org]

details:   http://hg.dovecot.org/dovecot-1.2/rev/9f3c8c59f8c4
changeset: 9653:9f3c8c59f8c4
user:      Timo Sirainen <tss at iki.fi>
date:      Sun Feb 12 03:32:20 2012 +0200
description:
SSL: Enable SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS flag for extra security.
This is to counter the "BEAST SSL" attack, although I don't think it's
practical to implement against IMAP/POP3/LMTP protocols. There's really no
way for attackers to inject any evil data before authentication, so the
password is safe. Post-authentication attacker could cause clients to
download evil emails, but even then clients don't typically redownload some
specific mail, so there's really no way to extract anything useful.

diffstat:

 src/login-common/ssl-proxy-openssl.c |  5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diffs (15 lines):

diff -r 031a4c2fabea -r 9f3c8c59f8c4 src/login-common/ssl-proxy-openssl.c
--- a/src/login-common/ssl-proxy-openssl.c	Sat Jan 28 23:58:50 2012 +0200
+++ b/src/login-common/ssl-proxy-openssl.c	Sun Feb 12 03:32:20 2012 +0200
@@ -817,7 +817,10 @@
 {
 	const char *cafile;
 
-	SSL_CTX_set_options(ssl_ctx, SSL_OP_ALL);
+	/* enable all SSL workarounds, except empty fragments as it
+	   makes SSL more vulnerable against attacks */
+	SSL_CTX_set_options(ssl_ctx, SSL_OP_ALL &
+			    ~SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS);
 
 	cafile = getenv("SSL_CA_FILE");
 	if (cafile != NULL) {