Fix for TROVE-2017-001 and bug 21278.
(Note: Instead of handling signed ints "correctly", we keep the old
behavior, except for the part where we would crash with -ftrapv.)
This reverts commit 5446cb8d3d.
The underlying revert was done in 0.2.6, since we aren't backporting
seccomp2 loosening fixes to 0.2.6. But the fix (for 17354) already
went out in 0.2.7.4-rc, so we shouldn't revert it in 0.2.7.
maint-0.2.7-redux is an attempt to try to re-create a plausible
maint-0.2.7 branch. I've started from the tor-0.2.7.6, and then I
merged maint-0.2.6 into the branch.
This has produced 2 conflicts: one related to the
rendcommon->rendcache move, and one to the authority refactoring.
Check size argument to memwipe() for underflow.
Closes bug #18089. Reported by "gk", patch by "teor".
Bugfix on 0.2.3.25 and 0.2.4.6-alpha (#7352),
commit 49dd5ef3 on 7 Nov 2012.
The length of auth_data from an INTRODUCE2 cell is checked when the
auth_type is recognized (1 or 2), but not for any other non-zero
auth_type. Later, auth_data is assumed to have at least
REND_DESC_COOKIE_LEN bytes, leading to a client-triggered out of bounds
read.
Fixed by checking auth_len before comparing the descriptor cookie
against known clients.
Fixes#15823; bugfix on 0.2.1.6-alpha.
This helps protect against bugs where any part of a buf_t's memory
is passed to a function that expects a NUL-terminated input.
It also closes TROVE-2016-10-001 (aka bug 20384).
Replace the 81 remaining fallbacks of the 100 originally introduced
in Tor 0.2.8.3-alpha in March 2016, with a list of 177 fallbacks
(123 new, 54 existing, 27 removed) generated in December 2016.
Resolves ticket 20170.
In get_token(), we could read one byte past the end of the
region. This is only a big problem in the case where the region
itself is (a) potentially hostile, and (b) not explicitly
nul-terminated.
This patch fixes the underlying bug, and also makes sure that the
one remaining case of not-NUL-terminated potentially hostile data
gets NUL-terminated.
Fix for bug 21018, TROVE-2016-12-002, and CVE-2016-1254
Tor 0.2.9 has a broader range of fixes and workarounds here, but for
0.2.8, we're just going to maintain the existing behavior.
(The alternative would be to backport both
1eba088054 and
16fcbd21c9 , but the latter is kind of
a subtle kludge in the configure.ac script, and I'm not a fan of
backporting that kind of thing.)
(OpenSSL 1.1 makes EVP_CIPHER_CTX opaque, _and_ adds acceleration
for counter mode on more architectures. So it won't work if we try
the older approach, and it might help if we try the newer one.)
Fixes bug 20588.
Apple is supposed to decorate their function declarations with
macros to indicate which OSX version introduced them, so that you
can tell the compiler that you want to build against certain
versions of OSX. But they forgot to do that for clock_gettime() and
getentropy(), both of which they introduced in 10.12.
This patch adds a kludge to the configure.ac script where, if we
detect that we are targeting OSX 10.11 or earlier, we don't even probe
to see if the two offending functions are present.
Closes ticket 20235.
In our code to write public keys to a string, for some unfathomable
reason since 253f0f160e, we would allocate a memory BIO, then
set the NOCLOSE flag on it, extract its memory buffer, and free it.
Then a little while later we'd free the memory buffer with
BUF_MEM_free().
As of openssl 1.1 this doesn't work any more, since there is now a
BIO_BUF_MEM structure that wraps the BUF_MEM structure. This
BIO_BUF_MEM doesn't get freed in our code.
So, we had a memory leak!
Is this an openssl bug? Maybe. But our code was already pretty
silly. Why mess around with the NOCLOSE flag here when we can just
keep the BIO object around until we don't need the buffer any more?
Fixes bug 20553; bugfix on 0.0.2pre8
This helps protect against bugs where any part of a buf_t's memory
is passed to a function that expects a NUL-terminated input.
It also closes TROVE-2016-10-001 (aka bug 20384).
Not telling the cmux would sometimes cause an assertion failure in
relay.c when we tried to get an active circuit and found an "active"
circuit with no cells.
Additionally, replace that assert with a test and a log message.
Fix for bug 20203. This is actually probably a bugfix on
0.2.8.1-alpha, specifically my code in 8b4e5b7ee9 where I
made circuit_mark_for_close_() do less in order to simplify our call
graph. Thanks to "cypherpunks" for help diagnosing.
For a brief moment in networkstatus_set_current_consensus(), the old
consensus has been freed, but the node_t objects still have dead
pointers to the routerstatus_t objects within it. During that
interval, we absolutely must not do anything that would cause Tor to
look at those dangling pointers.
Unfortunately, calling the (badly labeled!) current_consensus macro
or anything else that calls into we_use_microdescriptors_for_circuits(),
can make us look at the nodelist.
The fix is to make sure we identify the main consensus flavor
_outside_ the danger zone, and to make the danger zone much much
smaller.
Fixes bug 20103. This bug has been implicitly present for AGES; we
just got lucky for a very long time. It became a crash bug in
0.2.8.2-alpha when we merged 35bbf2e4a4 to make
find_dl_schedule start looking at the consensus, and 4460feaf28
which made node_get_all_orports less (accidentally) tolerant of
nodes with a valid ri pointer but dangling rs pointer.
This bug had existed since 0.2.4.7-alpha, but now that we have
FallbackDirs by default, it actually matters.
Fixes bug 19947; bugfix on 0.2.4.7-alpha or maybe 0.2.8.1-alpha.
Rubiate wrote the patch; teor wrote the changes file.
If we did not find a non-private IPaddress by iterating over interfaces,
we would try to get one via
get_interface_address6_via_udp_socket_hack(). This opens a datagram
socket with IPPROTO_UDP. Previously all our datagram sockets (via
libevent) used IPPROTO_IP, so we did not have that in the sandboxing
whitelist. Add (SOCK_DGRAM, IPPROTO_UDP) sockets to the sandboxing
whitelist. Fixes bug 19660.
This fixes#19608, allowing IPv6-only clients to use
microdescriptors, while preserving the ability of bridge clients
to have some IPv4 bridges and some IPv6 bridges.
Fix on c281c036 in 0.2.8.2-alpha.
asciidoc adds a timestamp at the end of a generated HTML file.
This timestamp is based on the date of the file but it can change
depending on the TZ environment variable.
Our sandboxing code would not allow us to write to stats/hidserv-stats,
causing tor to abort while trying to write stats. This was previously
masked by bug#19556.
When sandboxing is enabled, we could not write any stats to disk.
check_or_create_data_subdir("stats"), which prepares the private stats
directory, calls check_private_dir(), which also opens and not just stats() the
directory. Therefore, we need to also allow open() for the stats dir in our
sandboxing setup.
If we manually remove fallbacks in C by adding '/*' and '*/' on separate
lines, stem still parses them as being present, because it only looks at
the start of a line.
Add a comment to this effect in the generated source code.
Previously, we used !directory_fetches_from_authorities() to predict
that we would tunnel connections. But the rules have changed
somewhat over the course of 0.2.8
There was a > that should have been an ==, and a missing !. These
together prevented us from issuing a warning in the case that a
nickname matched an Unnamed node only.
Fixes bug 19203; bugfix on 0.2.3.1-alpha.
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.
