diff options
| author | Dr. Stephen Henson <steve@openssl.org> | 2010-02-17 18:38:10 +0000 |
|---|---|---|
| committer | Dr. Stephen Henson <steve@openssl.org> | 2010-02-17 18:38:10 +0000 |
| commit | 989238802aa096c083dd78d0add49ef67dc073da (patch) | |
| tree | 2aea6e3370833f4090ce0e05ff686dbdac62474b /doc | |
| parent | 9051fc538f93393d9e5540c9f981858178f5a1c1 (diff) | |
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.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/ssl/SSL_CTX_set_options.pod | 21 |
1 files changed, 12 insertions, 9 deletions
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 |