Allow an appliction to set libcurl specific SSL options. The first and
only options supported right now is CURLSSLOPT_ALLOW_BEAST.
It will make libcurl to disable any work-arounds the underlying SSL
library may have to address a known security flaw in the SSL3 and TLS1.0
protocol versions.
This is a reaction to us unconditionally removing that behavior after
this security advisory:
http://curl.haxx.se/docs/adv_20120124B.html
... it did however cause a lot of programs to fail because of old
servers not liking this work-around. Now programs can opt to decrease
the security in order to interoperate with old servers better.
OpenSSL added a work-around for a SSL 3.0/TLS 1.0 CBC vulnerability
(http://www.openssl.org/~bodo/tls-cbc.txt). In 0.9.6e they added a bit
to SSL_OP_ALL that _disables_ that work-around despite the fact that
SSL_OP_ALL is documented to do "rather harmless" workarounds.
The libcurl code uses the SSL_OP_ALL define and thus logically always
disables the OpenSSL fix.
In order to keep the secure work-around workding, the
SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS bit must not be set and this change
makes sure of this.
Reported by: product-security at Apple
SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG option enabling allowed successfull
interoperability with web server Netscape Enterprise Server 2.0.1 released
back in 1996 more than 15 years ago.
Due to CVE-2010-4180, option SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG has
become ineffective as of OpenSSL 0.9.8q and 1.0.0c. In order to mitigate
CVE-2010-4180 when using previous OpenSSL versions we no longer enable
this option regardless of OpenSSL version and SSL_OP_ALL definition.
If no SSLv2 was detected in OpenSSL by configure, then we enforce the
OPENSSL_NO_SSL2 define as it seems some people report it not being
defined properly in the OpenSSL headers.
Move calling of ERR_remove_state(0) a.k.a ERR_remove_thread_state(NULL)
from Curl_ossl_close_all() to Curl_ossl_cleanup().
In this way ERR_remove_state(0) is now only called in libcurl by
curl_global_cleanup(). Previously it would get called by functions
curl_easy_cleanup(), curl_multi_cleanup and potentially each time a
connection was removed from a connection cache leading to premature
destruction of OpenSSL's thread local state hash.
Multi-threaded apps using OpenSSL enabled libcurl should still call
function ERR_remove_state(0) or ERR_remove_thread_state(NULL) at the
very end end of threads that do not call curl_global_cleanup().
ossl_connect_common() now checks whether or not 'struct
connectdata->state' is equal 'ssl_connection_complete' and if so, will
return CURLE_OK with 'done' set to 'TRUE'. This check prevents
ossl_connect_common() from creating a new ssl connection on an existing
ssl session which causes openssl to fail when it tries to parse an
encrypted TLS packet since the cipher data was effectively thrown away
when the new ssl connection was created.
Bug: http://curl.haxx.se/mail/lib-2010-11/0169.html
If you use a custom Host: name in a request to a SSL server, libcurl
will now use that given name when it verifies the server certificate to
be correct rather than using the host name used in the actual URL.
When given a custom host name in a Host: header, we can use it for
several different purposes other than just cookies, so we rename it and
use it for SSL SNI etc.
Commit 496002ea1c (released in 7.20.1) broke FTPS when using the
multi interface and OpenSSL was used. The condition for the non-blocking
connect was incorrect.
Reported by: Georg Lippitsch
Bug: http://curl.haxx.se/mail/lib-2010-07/0270.html
Was seeing spurious SSL connection aborts using libcurl and
OpenSSL. I tracked it down to uncleared error state on the
OpenSSL error stack - patch attached deals with that.
Rough idea of problem:
Code that uses libcurl calls some library that uses OpenSSL but
don't clear the OpenSSL error stack after an error.
ssluse.c calls SSL_read which eventually gets an EWOULDBLOCK from
the OS. Returns -1 to indicate an error
ssluse.c calls SSL_get_error. First thing, SSL_get_error calls
ERR_get_error to check the OpenSSL error stack, finds an old
error and returns SSL_ERROR_SSL instead of SSL_ERROR_WANT_READ or
SSL_ERROR_WANT_WRITE.
ssluse.c returns an error and aborts the connection
Solution:
Clear the openssl error stack before calling SSL_* operation if
we're going to call SSL_get_error afterwards.
Notes:
This is much more likely to happen with multi because it's easier
to intersperse other calls to the OpenSSL library in the same
thread.
John-Mark Bell filed bug #3000052 that identified a problem (with
an associated patch) with the OpenSSL handshake state machine
when the multi interface is used:
Performing an https request using a curl multi handle and using
select or epoll to wait for events results in a hang. It appears
that the cause is the fix for bug #2958179, which makes
ossl_connect_common unconditionally return from the step 2 loop
when fetching from a multi handle.
When ossl_connect_step2 has completed, it updates
connssl->connecting_state to ssl_connect_3. ossl_connect_common
will then return to the caller, as a multi handle is in
use. Eventually, the client code will call curl_multi_fdset to
obtain an updated fdset to select or epoll on. For https
requests, curl_multi_fdset will cause https_getsock to be called.
https_getsock will only return a socket handle if the
connecting_state is ssl_connect_2_reading or
ssl_connect_2_writing. Therefore, the client will never obtain a
valid fdset, and thus not drive the multi handle, resulting in a
hang.
(http://curl.haxx.se/bug/view.cgi?id=3000052)
FTP(S) use two connections that can be set to different recv and
send functions independently, so by introducing recv+send pairs
in the same manner we already have sockets/connections we can
work with FTPS fine.
This commit fixes the FTPS regression introduced in change d64bd82.
Howard Chu brought the bulk work of this patch that properly
moves out the sending and recving of data to the parts of the
code that are properly responsible for the various ways of doing
so.
Daniel Stenberg assisted with polishing a few bits and fixed some
minor flaws in the original patch.
Another upside of this patch is that we now abuse CURLcodes less
with the "magic" -1 return codes and instead use CURLE_AGAIN more
consistently.
ossl_connect_step3() increments an SSL session handle reference counter on
each call. When sessions are re-used this reference counter may be
incremented many times, but it will be decremented only once when done (by
Curl_ossl_session_free()); and the internal OpenSSL data will not be freed
if this reference count remains positive. When a session is re-used the
reference counter should be corrected by explicitly calling
SSL_SESSION_free() after each consecutive SSL_get1_session() to avoid
introducing a memory leak.
(http://curl.haxx.se/bug/view.cgi?id=2926284)
