diff options
author | Dr. Stephen Henson <steve@openssl.org> | 2010-02-17 18:38:10 +0000 |
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committer | Dr. Stephen Henson <steve@openssl.org> | 2010-02-17 18:38:10 +0000 |
commit | 989238802aa096c083dd78d0add49ef67dc073da (patch) | |
tree | 2aea6e3370833f4090ce0e05ff686dbdac62474b | |
parent | 9051fc538f93393d9e5540c9f981858178f5a1c1 (diff) | |
download | openssl-new-989238802aa096c083dd78d0add49ef67dc073da.tar.gz |
Allow renegotiation if SSL_OP_LEGACY_SERVER_CONNECT is set as well as
initial connection to unpatched servers. There are no additional security
concerns in doing this as clients don't see renegotiation during an
attack anyway.
-rw-r--r-- | CHANGES | 2 | ||||
-rw-r--r-- | doc/ssl/SSL_CTX_set_options.pod | 21 | ||||
-rw-r--r-- | ssl/t1_lib.c | 4 |
3 files changed, 15 insertions, 12 deletions
@@ -877,7 +877,7 @@ [Bodo Moeller] *) Add option SSL_OP_LEGACY_SERVER_CONNECT which will allow clients to - connect (but not renegotiate) with servers which do not support RI. + connect and renegotiate with servers which do not support RI. Until RI is more widely deployed this option is enabled by default. [Steve Henson] diff --git a/doc/ssl/SSL_CTX_set_options.pod b/doc/ssl/SSL_CTX_set_options.pod index 3e61a36e17..1abda2898e 100644 --- a/doc/ssl/SSL_CTX_set_options.pod +++ b/doc/ssl/SSL_CTX_set_options.pod @@ -237,7 +237,7 @@ OpenSSL 0.9.8m and later always attempts to use secure renegotiation as described in RFC5746. This counters the prefix attack described in CVE-2009-3555 and elsewhere. -The deprecated and highly broken SSLv2 protocol does not support secure +The deprecated and highly broken SSLv2 protocol does not support renegotiation at all: its use is B<strongly> discouraged. This attack has far reaching consequences which application writers should be @@ -276,10 +276,14 @@ was refused. =head2 Patched OpenSSL client and unpatched server. If the option B<SSL_OP_LEGACY_SERVER_CONNECT> is set then initial connections -between patched OpenSSL clients and unpatched servers succeed. This option -is currently set by default even though it has security implications: otherwise -it would be impossible to connect to unpatched servers (i.e. all of them -initially) and this is clearly not acceptable. +and renegotiation between patched OpenSSL clients and unpatched servers +succeeds. + +This option is currently set by default even though it has security +implications: otherwise it would be impossible to connect to unpatched servers +(i.e. all of them initially) and this is clearly not acceptable. Renegotiation +is permitted because this does not add any additional security issues: during +an attack clients do not see any renegotiations anyway. As more servers become patched the option B<SSL_OP_LEGACY_SERVER_CONNECT> will B<not> be set by default in a future version of OpenSSL. @@ -292,10 +296,9 @@ unpatched servers (and thus avoid any security issues) should always B<clear> B<SSL_OP_LEGACY_SERVER_CONNECT> using SSL_CTX_clear_options() or SSL_clear_options(). -Renegotiation between a patched OpenSSL client and unpatched server follows -the same scheme as between an unpatched client and a patched OpenSSL server: -i.e. it is not permitted unless the option -B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> is set. +As in the previous case if the option +B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> is set then renegotiation +B<always> succeeds. =head1 RETURN VALUES diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 4cb171e6d4..e8bc34c111 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -1157,8 +1157,8 @@ int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in * which doesn't support RI so for the immediate future tolerate RI * absence on initial connect only. */ - if (!renegotiate_seen && - (s->new_session || !(s->options & SSL_OP_LEGACY_SERVER_CONNECT)) + if (!renegotiate_seen + && !(s->options & SSL_OP_LEGACY_SERVER_CONNECT) && !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) { *al = SSL_AD_HANDSHAKE_FAILURE; |