Fixes bug 40078.
As reported by hdevalence our batch verification logic can cause an assert
crash.
The assert happens because when the batch verification of ed25519-donna fails,
the code in `ed25519_checksig_batch()` falls back to doing a single
verification for each signature.
The crash occurs because batch verification failed, but then all signatures
individually verified just fine.
That's because batch verification and single verification use a different
equation which means that there are sigs that can pass single verification
but fail batch verification.
Fixing this would require modding ed25519-donna which is not in scope for
this ticket, and will be soon deprecated in favor of arti and
ed25519-dalek, so my branch instead removes batch verification.
This issue was reported by Jann Horn part of Google's Project Zero.
Jann's one-sentence summary: entry/middle relays can spoof RELAY_END cells on
half-closed streams, which can lead to stream confusion between OP and
exit.
Fixes#40389
Previously, we would detect errors from a missing RNG
implementation, but not failures from the RNG code itself.
Fortunately, it appears those failures do not happen in practice
when Tor is using OpenSSL's default RNG implementation. Fixes bug
40390; bugfix on 0.2.8.1-alpha. This issue is also tracked as
TROVE-2021-004. Reported by Jann Horn at Google's Project Zero.
As of GCC 11.1.1, the compiler warns us about code like this:
if (a)
b;
c;
and that's a good thing: we wouldn't want to "goto fail". But we
had an instance if this in circuituse.c, which was making our
compilation sad.
Fixes bug 40380; bugfix on 0.3.0.1-alpha.
This function has been a no-op since Libevent 2.0.4-alpha, when
libevent got an arc4random() implementation. Libevent has finally
removed it, which will break our compilation unless we stop calling
it. (This is currently breaking compilation in OSS-fuzz.)
Closes#40371.
We were looking for the first instance of "directory-signature "
when instead the correct behavior is to look for the first instance
of "directory-signature " at the start of a line.
Unfortunately, this can be exploited as to crash authorities while
they're voting.
Fixes#40316; bugfix on 0.2.2.4-alpha. This is TROVE-2021-002,
also tracked as CVE-2021-28090.
David Goulet
Alexander Færøy
George Kadianakis
Nick Mathewson