If OpenSSL fails to generate an RSA key, do not retain a dangling
pointer to the previous (uninitialized) key value. The impact here
should be limited to a difficult-to-trigger crash, if OpenSSL is
running an engine that makes key generation failures possible, or if
OpenSSL runs out of memory. Fixes bug 19152; bugfix on
0.2.1.10-alpha. Found by Yuan Jochen Kang, Suman Jana, and Baishakhi
Ray.
This is potentially scary stuff, so let me walk through my analysis.
I think this is a bug, and a backport candidate, but not remotely
triggerable in any useful way.
Observation 1a:
Looking over the OpenSSL code here, the only way we can really fail in
the non-engine case is if malloc() fails. But if malloc() is failing,
then tor_malloc() calls should be tor_asserting -- the only way that an
attacker could do an exploit here would be to figure out some way to
make malloc() fail when openssl does it, but work whenever Tor does it.
(Also ordinary malloc() doesn't fail on platforms like Linux that
overcommit.)
Observation 1b:
Although engines are _allowed_ to fail in extra ways, I can't find much
evidence online that they actually _do_ fail in practice. More evidence
would be nice, though.
Observation 2:
We don't call crypto_pk_generate*() all that often, and we don't do it
in response to external inputs. The only way to get it to happen
remotely would be by causing a hidden service to build new introduction
points.
Observation 3a:
So, let's assume that both of the above observations are wrong, and the
attacker can make us generate a crypto_pk_env_t with a dangling pointer
in its 'key' field, and not immediately crash.
This dangling pointer will point to what used to be an RSA structure,
with the fields all set to NULL. Actually using this RSA structure,
before the memory is reused for anything else, will cause a crash.
In nearly every function where we call crypto_pk_generate*(), we quickly
use the RSA key pointer -- either to sign something, or to encode the
key, or to free the key. The only exception is when we generate an
intro key in rend_consider_services_intro_points(). In that case, we
don't actually use the key until the intro circuit is opened -- at which
point we encode it, and use it to sign an introduction request.
So in order to exploit this bug to do anything besides crash Tor, the
attacker needs to make sure that by the time the introduction circuit
completes, either:
* the e, d, and n BNs look valid, and at least one of the other BNs is
still NULL.
OR
* all 8 of the BNs must look valid.
To look like a valid BN, *they* all need to have their 'top' index plus
their 'd' pointer indicate an addressable region in memory.
So actually getting useful data of of this, rather than a crash, is
going to be pretty damn hard. You'd have to force an introduction point
to be created (or wait for one to be created), and force that particular
crypto_pk_generate*() to fail, and then arrange for the memory that the
RSA points to to in turn point to 3...8 valid BNs, all by the time the
introduction circuit completes.
Naturally, the signature won't check as valid [*], so the intro point
will reject the ESTABLISH_INTRO cell. So you need to _be_ the
introduction point, or you don't actually see this information.
[*] Okay, so if you could somehow make the 'rsa' pointer point to a
different valid RSA key, then you'd get a valid signature of an
ESTABLISH_INTRO cell using a key that was supposed to be used for
something else ... but nothing else looks like that, so you can't use
that signature elsewhere.
Observation 3b:
Your best bet as an attacker would be to make the dangling RSA pointer
actually contain a fake method, with a fake RSA_private_encrypt
function that actually pointed to code you wanted to execute. You'd
still need to transit 3 or 4 pointers deep though in order to make that
work.
Conclusion:
By 1, you probably can't trigger this without Tor crashing from OOM.
By 2, you probably can't trigger this reliably.
By 3, even if I'm wrong about 1 and 2, you have to jump through a pretty
big array of hoops in order to get any kind of data leak or code
execution.
So I'm calling it a bug, but not a security hole. Still worth
patching.
Fortunately, the arithmetic cannot actually overflow, so long as we
*always* check for the size of potentially hostile input before
copying it. I think we do, though. We do check each line against
MAX_LINE_LENGTH, and each object name or object against
MAX_UNPARSED_OBJECT_SIZE, both of which are 128k. So to get this
overflow, we need to have our memarea allocated way way too high up
in RAM, which most allocators won't actually do.
Bugfix on 0.2.1.1-alpha, where memarea was introduced.
Found by Guido Vranken.
Previously, if the header was present, we'd proceed even if the
function wasn't there.
Easy fix for bug 19161. A better fix would involve trying harder to
find libscrypt_scrypt.
We use a pretty specific pair of autoconf tests here to make sure
that we only add this code when:
a) a 64-bit signed multiply fails to link,
AND
b) the same 64-bit signed multiply DOES link correctly when
__mulodi4 is defined.
Closes ticket 19079.
The routerinfo we pass to routerinfo_incompatible_with_extrainfo is
the latest routerinfo for the relay. The signed_descriptor_t, on
the other hand, is the signed_descriptor_t that corresponds to the
extrainfo. That means we should be checking the digest256 match
with that signed_descriptor_t, not with the routerinfo.
Fixes bug 17150 (and 19017); bugfix on 0.2.7.2-alpha.
When parsing detached signature, we make sure that we use the length of the
digest algorithm instead of an hardcoded DIGEST256_LEN in order to avoid
comparing bytes out of bound with a smaller digest length such as SHA1.
Fixes#19066
Signed-off-by: David Goulet <dgoulet@torproject.org>
Previously we'd only check whether the hardening options succeeded
at the compile step. Now we'll try to link with them too, and tell
the user in advance if something seems likely to go wrong.
Closes ticket 18895.
We know there are overflows in curve25519-donna-c32, so we'll have
to have that one be fwrapv.
Only apply the asan, ubsan, and trapv options to the code that does
not need to run in constant time. Those options introduce branches
to the code they instrument.
(These introduced branches should never actually be taken, so it
might _still_ be constant time after all, but branch predictors are
complicated enough that I'm not really confident here. Let's aim for
safety.)
Closes 17983.
Make directory authorities write the v3-status-votes file out
to disk earlier in the consensus process, so we have the votes
even if we abort the consensus process later on.
Resolves ticket 19036.
In dirserv_compute_performance_thresholds, we allocate arrays based
on the length of 'routers', a list of routerinfo_t, but loop over
the nodelist. The 'routers' list may be shorter when relays were
filtered by routers_make_ed_keys_unique, leading to an out-of-bounds
write on directory authorities.
This bug was originally introduced in 26e89742, but it doesn't look
possible to trigger until routers_make_ed_keys_unique was introduced
in 13a31e72.
Fixes bug 19032; bugfix on tor 0.2.8.2-alpha.
This makes our compilation options checks in autoconf work better on
systems that already define _FORTIFY_SOURCE.
Fixes at least one case of bug 18841; bugfix on 0.2.3.17-beta. Patch
from "trudokal".
Previously, we were using the generic schedule for some downloads,
and the consensus schedule for others.
Resolves ticket 18816; fix on fddb814fe in 0.2.4.13-alpha.
We used to be locked in to the "tap" handshake length, and now we can
handle better handshakes like "ntor".
Resolves ticket 18998.
I checked that relay_send_command_from_edge() behaves fine when you
hand it a payload with length 0. Clients behave fine too, since current
clients remain strict about the required length in the rendezvous2 cells.
(Clients will want to become less strict once they have an alternate
format that they're willing to receive.)
This improves client anonymity and avoids directory header tampering.
The extra load on the authorities should be offset by the fallback
directories feature.
This also simplifies the fixes to #18809.
Delete an unnecessary check for non-preferred IP versions.
Allows clients which can't reach any directories of their
preferred IP address version to get directory documents.
Patch on #17840 in 0.2.8.1-alpha.
After #17840 in 0.2.8.1-alpha, we incorrectly chose an IPv4
address for all DIRIND_ONEHOP directory connections,
even if the routerstatus didn't have an IPv4 address.
This likely affected bridge clients with IPv6 bridges.
Resolves#18921.
The problem is that "q" is always set on the first iteration even
if the question is not a supported question. This set of "q" is
not necessary, and will be handled after exiting the loop if there
if a supported q->type was found.
[Changes file by nickm]
lease enter the commit message for your changes. Lines starting
* SHA-3/SHAKE use little endian for certain things, so byteswap as
needed.
* The code was written under the assumption that unaligned access to
quadwords is allowed, which isn't true particularly on non-Intel.
As well as the existing reports of IPv6 address additions or removals,
the script now warns when keys change but IPv4:ORPort or
IPv6:IPv6ORPort remain the same.
Existing checks for other whitelist detail changes have also
been re-worded and upgraded to warnings.
This makes it easier for changes to be identified so operators can
be contacted to confirm whether the change is stable.
Apparently somewhere along the line we decided that MIN might be
missing.
But we already defined it (if it was missing) in compat.h, which
everybody includes.
Closes ticket 18889.
When we connect to a hidden service as a client we may need three internal
circuits, one for the descriptor retrieval, introduction, and rendezvous.
Let's try to make sure we have them. Closes#13239.
Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Unlike tor_assert(), these macros don't abort the process. They're
good for checking conditions we want to warn about, but which don't
warrant a full crash.
This commit also changes the default implementation for
tor_fragile_assert() to tor_assert_nonfatal_unreached_once().
Closes ticket 18613.
Document this convention.
Add a script to post-process .gcov files in order to stop nagging us
about excluded lines.
Teach cov-diff to handle these post-processed files.
Closes ticket 16792
When the directory authorities refuse a bad relay's descriptor,
encourage the relay operator to contact us. Many relay operators
won't notice this line in their logs, but it's a win if even a
few learn why we don't like what their relay was doing.
Resolves ticket 18760.
I didn't specify a contact mechanism (e.g. an email address), because
every time we've done that in the past, a few years later we noticed
that the code was pointing people to an obsolete contact address.
Also, put libor-testing.a at a better position in the list of
libraries, to avoid linker errors.
This is a fix, or part of a fix, for 18490.
Conflicts:
src/test/include.am
This changes simply renames them by removing "Testing" in front of them and
they do not require TestingTorNetwork to be enabled anymore.
Fixes#18481
Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Yes, we could cast to unsigned char first, but it's probably safest
to just use our own (in test_util), or remove bad-idea features that
we don't use (in readpassphrase.c).
Fixes 18728.
Only when we were actually flushing the cell stats to a controller
would we free them. Thus, they could stay in RAM even after the
circuit was freed (eg if we didn't have any controllers).
Fixes bug 18673; bugfix on 0.2.5.1-alpha.
We added these a while ago, but they do no actual good, and
cause implicit declaration warnings in some situations. Rather than
just adding stdint.h, it's easier to remove the exit() calls
as redundant.
Fixes bug 18626; bugfix from "cypherpunks"
This change allows us to simplify path selection for clients, and it
should have minimal effect in practice since >99% of Guards already have
the Stable flag. Implements ticket 18624.
Regardless of the setting of ExtendAllowPrivateAddresses.
This fixes a bug with pluggable transports that ignore the
(potentially private) address in their bridge line.
Fixes bug 18517; bugfix on 23b088907f in tor-0.2.8.1-alpha.
When requesting extrainfo descriptors from a trusted directory
server, check whether it is an authority or a fallback directory
which supports extrainfo descriptors.
Fixes bug 18489; bugfix on 90f6071d8d in tor-0.2.4.7-alpha.
Reported by "atagar", patch by "teor".
Downgrade logs and backtraces about IP versions to
info-level. Only log backtraces once each time tor runs.
Assists in diagnosing bug 18351; bugfix on c3cc8e16e in
tor-0.2.8.1-alpha.
Reported by "sysrqb" and "Christian", patch by "teor".
I had a half-built mechanism to track, during the voting process,
whether the Ed25519 value (or lack thereof) reflected a true
consensus among the authorities. But we never actually inserted this
field in the consensus.
The key idea here is that we first attempt to match up votes by pairs
of <Ed,RSA>, where <Ed> can be NULL if we're told that there is no
Ed key. If this succeeds, then we can treat all those votes as 'a
consensus for Ed'. And we can include all other votes with a
matching RSA key and no statement about Ed keys as being "also about
the same relay."
After that, we look for RSA keys we haven't actually found an entry
for yet, and see if there are enough votes for them, NOT considering
Ed keys. If there are, we match them as before, but we treat them
as "not a consensus about ed".
When we include an entry in a consensus, if it does not reflect a
consensus about ed keys, then we include a new NoEdConsensus flag on
it.
This is all only for consensus method 22 or later.
Also see corresponding dir-spec patch.
When generating a vote, and we have two routerinfos with the same ed
key, omit the one published earlier.
This was supposed to have been solved by key pinning, but when I
made key pinning optional, I didn't realize that this would jump up
and bite us. It is part of bug 18318, and the root cause of 17668.
If we're a server with no address configured, resolve_my_hostname
will need this. But not otherwise. And the preseeding itself can
consume a few seconds if like tails we have no resolvers.
Fixes bug 18548.
