OpenSSL 1.0.0 added an implementation of TLS session tickets, a
"feature" that let session resumption occur without server-side state
by giving clients an encrypted "ticket" that the client could present
later to get the session going again with the same keys as before.
OpenSSL was giving the keys to decrypt these tickets the lifetime of
the SSL contexts, which would have been terrible for PFS if we had
long-lived SSL contexts. Fortunately, we don't. Still, it's pretty
bad. We should also drop these, since our use of the extension stands
out with our non-use of session cacheing.
Found by nextgens. Bugfix on all versions of Tor when built with
openssl 1.0.0 or later. Fixes bug 7139.
I don't personally agree that this is likely to be easy to exploit,
and some initial experimention I've done suggests that cache-miss
times are just plain too fast to get useful info out of when they're
mixed up with the rest of Tor's timing noise. Nevertheless, I'm
leaving Robert's initial changelog entry in the git history so that he
can be the voice of reason if I'm wrong. :)
Manually removed range 0.116.0.0 to 0.119.255.255 which Maxmind says is
assigned to AT. This is very likely a bug in their database, because
0.0.0.0/8 is a reserved range.
This fixes a DoS issue where a client could send so much data in 5
minutes that they exhausted the server's RAM. Fix for bug 5934 and
6007. Bugfix on 0.2.0.20-rc, which enabled the v2 handshake.
It appears that when OpenSSL negotiates a 1.1 or 1.2 connection, and it
decides to renegotiate, the client will send a record with version "1.0"
rather than with the current TLS version. This would cause the
connection to fail whenever both sides had OpenSSL 1.0.1, and the v2 Tor
handshake was in use.
As a workaround, disable TLS 1.1 and TLS 1.2. When a later version of
OpenSSL is released, we can make this conditional on running a fixed
version of OpenSSL.
Alternatively, we could disable TLS 1.1 and TLS 1.2 only on the client
side. But doing it this way for now means that we not only fix TLS with
patched clients; we also fix TLS when the server has this patch and the
client does not. That could be important to keep the network running
well.
Fixes bug 6033.
It turns out that if you set the third argument of
__attribute__(format) to 0, GCC and Clang will check the format
argument without expecting to find variadic arguments. This is the
correct behavior for vsnprintf, vasprintf, and vscanf.
I'm hoping this will fix bug 5969 (a clang warning) by telling clang that
the format argument to tor_vasprintf is indeed a format string.
The underlying strtoX functions handle overflow by saturating and
setting errno to ERANGE. If the min/max arguments to the
tor_parse_* functions are equal to the minimum/maximum of the
underlying type, then with the old approach, we wouldn't treat a
too-large value as genuinely broken.
Found this while looking at bug 5786; bugfix on 19da1f36 (in Tor
0.0.9), which introduced these functions.
This fixes a side-channel attack on the (fortunately unused!)
BridgePassword option for bridge authorities. Fix for bug 5543;
bugfix on 0.2.0.14-alpha.
This mitigates an attack proposed by wanoskarnet, in which all of a
client's bridges collude to restrict the exit nodes that the client
knows about. Fixes bug 5343.
in Makefile.am, we used it without quoting it, causing build failure if
your openssl/sed/sha1sum happened to live in a directory with a space in
it (very common on windows)
