Nick Mathewson [Mon, 28 Jun 2021 13:08:31 +0000 (09:08 -0400)]
Suppress strict-prototypes warning on NSS pk11pub.h header
We already did this in a couple of places, but there are more that
we didn't get. This is necessary for systems with versions of
NSS that don't do their prototypes properly.
David Goulet [Thu, 3 Jun 2021 13:33:21 +0000 (09:33 -0400)]
TROVE-2021-003: Check layer_hint before half-closed end and resolve cells
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.
Nick Mathewson [Mon, 17 May 2021 12:50:01 +0000 (08:50 -0400)]
Assert on _all_ failures from RAND_bytes().
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.
Daniel Pinto [Wed, 7 Apr 2021 22:46:59 +0000 (23:46 +0100)]
Make SAVECONF keep only one backup and add sandbox rules for it. #40317
When seccomp sandbox is active, SAVECONF failed because it was not
able to save the backup files for torrc. This commit simplifies
the implementation of SAVECONF and sandbox by making it keep only
one backup of the configuration file.
Nick Mathewson [Fri, 7 May 2021 16:09:41 +0000 (12:09 -0400)]
Add a sandbox workaround for Glibc 2.33
This change permits the newfstatat() system call, and fixes issues
40382 (and 40381).
This isn't a free change. From the commit:
// Libc 2.33 uses this syscall to implement both fstat() and stat().
//
// The trouble is that to implement fstat(fd, &st), it calls:
// newfstatat(fs, "", &st, AT_EMPTY_PATH)
// We can't detect this usage in particular, because "" is a pointer
// we don't control. And we can't just look for AT_EMPTY_PATH, since
// AT_EMPTY_PATH only has effect when the path string is empty.
//
// So our only solution seems to be allowing all fstatat calls, which
// means that an attacker can stat() anything on the filesystem. That's
// not a great solution, but I can't find a better one.
David Goulet [Thu, 8 Apr 2021 18:08:28 +0000 (14:08 -0400)]
guard: Don't check bridge transport name when selecting eligible guards
This is related to ticket #40360 which found this problem when a Bridge entry
with a transport name (let say obfs4) is set without a fingerprint:
Bridge obfs4 <IP>:<PORT> cert=<...> iat-mode=0
(Notice, no fingerprint between PORT and "cert=")
Problem: commit 09c6d0324626ffa349c7eed66d9ede92ecd71583 added a check in
get_sampled_guard_for_bridge() that would return NULL if the selected bridge
did not have a valid transport name (that is the Bridge transport name that
corresponds to a ClientTransportPlugin).
Unfortuantely, this function is also used when selecting our eligible guards
which is done *before* the transport list is populated and so the added check
for the bridge<->transport name is querying an empty list of transports
resulting in always returning NULL.
For completion, the logic is: Pick eligible guards (use bridge(s) if need be)
then for those, initiate a connection to the pluggable transport proxy and
then populate the transport list once we've connected.
Back to get_sampled_guard_for_bridge(). As said earlier, it is used when
selecting our eligible guards in a way that prevents us from selecting
duplicates. In other words, if that function returns non-NULL, the selection
continues considering the bridge was sampled before. But if it returns NULL,
the relay is added to the eligible list.
This bug made it that our eligible guard list was populated with the *same*
bridge 3 times like so (remember no fingerprint):
When tor starts, it will find the bridge fingerprint by connecting to it and
will then update the primary guard list by calling
entry_guard_learned_bridge_identity() which then goes and update only 1 single
entry resulting in this list:
[debug] sampled_guards_update_consensus_presence(): Sampled guard [bridge] ($<FINGERPRINT>) is still listed.
[debug] sampled_guards_update_consensus_presence(): Sampled guard [bridge] ($0000000000000000000000000000000000000000) is still listed.
[debug] sampled_guards_update_consensus_presence(): Sampled guard [bridge] ($0000000000000000000000000000000000000000) is still listed.
And here lies the problem, now tor is stuck attempting to wait for a valid
descriptor for at least 2 guards where the second one is a bunch of zeroes and
thus tor will never fully bootstraps:
[info] I learned some more directory information, but not enough to build a
circuit: We're missing descriptors for 1/2 of our primary entry guards
(total microdescriptors: 6671/6703). That's ok. We will try to fetch missing
descriptors soon.
Now, why passing the fingerprint then works? This is because the list of
guards contains 3 times the same bridge but they all have a fingerprint and so
the descriptor can be found and tor can bootstraps.
The solution here is to entirely remove the transport name check in
get_sampled_guard_for_bridge() since the transport_list is empty at that
point. That way, the eligible guard list only gets 1 entry, the bridge, and
can then go on to bootstrap properly.
It is OK to do so since when launching a bridge descriptor fetch, we validate
that the bridge transport name is OK and thus avoid connecting to a bridge
without a ClientTransportPlugin. If we wanted to keep the check in place, we
would need to populate the transport_list much earlier and this would require
a much bigger refactoring.
Fixes #40360
Signed-off-by: David Goulet <dgoulet@torproject.org>
Nick Mathewson [Wed, 7 Apr 2021 14:18:44 +0000 (10:18 -0400)]
Try making our configure.ac script build with AC 2.70.
In versions <=2.69, according to the autoconf docs, AC_PROG_CC_C99
is needed with some compilers, if they require extra arguments to
build C99 programs. In versions >=2.70, AC_PROG_CC checks for these
compilers automatically, and so the AC_PROG_CC_C99 macro is
obsolete.
So, what can you do if you want your script to work right with both
autoconf versions? IIUC, neither including AC_PROG_CC_C99 macro nor
leaving it out will give you the right behavior with both versions.
It looks like you need to look at the autoconf version explicitly.
(Now, the autoconf manual implies that it's "against autoconf
philosophy" to look at the autoconf version rather than trying the
behavior to see if it works, but they don't actually tell you how to
detect recoverably at autoconf-time whether a macro is obsolete or
not, and I can't find a way to do that.)
So, is it safe to use m4_version_prereq, like I do here? It isn't
listed in the autoconf 2.63 manual (which is the oldest version we
support). But a mailing list message [1] (which added the
documentation back in 2008) implies that m4_version_prereq has been
there since "at least back to autoconf 2.59".
I am basing this patch against Tor 0.3.5 since, if autoconf 2.70
becomes widespread before 0.3.5 is unsupported, we might need this
patch to continue 0.3.5 development. But I don't think we should
backport farther than 0.4.5 until/unless that actually happens.
Daniel Pinto [Thu, 25 Mar 2021 01:23:04 +0000 (01:23 +0000)]
Fix glob processing on BSD systems. #40318
On Linux systems, glob automatically ignores the errors ENOENT and
ENOTDIR because they are expected during glob expansion. But BSD
systems do not ignore these, resulting in glob failing when globs
expand to invalid paths. This is fixed by adding a custom error
handler that ignores only these two errors and removing the
GLOB_ERR flag as it makes glob fail even if the error handler
ignores the error and is unnecessary as the error handler will
make glob fail on all other errors anyway.
Nick Mathewson [Wed, 3 Mar 2021 20:14:31 +0000 (15:14 -0500)]
Fix detection of point to insert signatures on a pending consensus.
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.
projects / thirdparty / tor.git / log
