We have a mock for our RSA key generation function, so we now wire
it to pk_generate(). This covers all the cases that were not using
pk_generate() before -- all ~93 of them.
The functions it warns about are:
assert, memcmp, strcat, strcpy, sprintf, malloc, free, realloc,
strdup, strndup, calloc.
Also, fix a few lingering instances of these in the code. Use other
conventions to indicate _intended_ use of assert and
malloc/realloc/etc.
Previously setup_capture_of_logs would prevent log messages from
going to the console entirely. That's a problem, since sometimes
log messages are bugs! Now setup_capture_of_logs() acts sensibly.
If you really do need to keep a message from going to the console
entirely, there is setup_full_capture_of_logs(). But only use that
if you're prepared to make sure that there are no extraneous
messages generated at all.
OpenBSD removes this function, and now that Tor requires Libevent 2,
we should also support the OpenBSD Libevent 2.
Fixes bug 19904; bugfix on 0.2.5.4-alpha.
To maintain precision, to get nanoseconds, we were multiplying our
tick count by a billion, then dividing by ticks-per-second. But
that apparently isn't such a great idea, since ticks-per-second is
sometimes a billion on its own, so our intermediate result was
giving us attoseconds.
When you're counting in attoseconds, you can only fit about 9
seconds into an int64_t, which is not so great for our purposes.
Instead, we now simplify the 1000000000/1000000000 fraction before
we start messing with nanoseconds. This has potential to mess us
up if some future MS version declares that performance counters will
use 1,000,000,007 units per second, but let's burn that bridge when
we come to it.
* Raise limit: 16k isn't all that high.
* Don't log when limit exceded; log later on.
* Say "over" when we log more than we say we log.
* Add target version to changes file
This code uses QueryPerformanceCounter() [**] on Windows,
mach_absolute_time() on OSX, clock_gettime() where available, and
gettimeofday() [*] elsewhere.
Timer types are stored in an opaque OS-specific format; the only
supported operation is to compute the difference between two timers.
[*] As you know, gettimeofday() isn't monotonic, so we include
a simple ratchet function to ensure that it only moves forward.
[**] As you may not know, QueryPerformanceCounter() isn't actually
always as monotonic as you might like it to be, so we ratchet that
one too.
We also include a "coarse monotonic timer" for cases where we don't
actually need high-resolution time. This is GetTickCount{,64}() on
Windows, clock_gettime(CLOCK_MONOTONIC_COARSE) on Linux, and falls
back to regular monotonic time elsewhere.
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.
We introduded a shadowed variable, thereby causing a log message to
be wrong. Fixes 19578. I believe the bug was introduced by
54d7d31cba in 0.2.2.29-beta.
I grepped and hand-inspected the "it's" instances, to see if any
were supposed to be possessive. While doing that, I found a
"the the", so I grepped to see if there were any more.
Only some very ancient distributions don't ship with Libevent 2 anymore,
even the oldest supported Ubuntu LTS version has it. This allows us to
get rid of a lot of compat code.
Validate that tv_usec inputs to tv_udiff and tv_mdiff are in range.
Do internal calculations in tv_udiff and tv_mdiff in 64-bit,
which makes the function less prone to integer overflow,
particularly on platforms where long and time_t are 32-bit,
but tv_sec is 64-bit, like some BSD configurations.
Check every addition and subtraction that could overflow.
Make sure to memset(0) the destination buffer so we don't leave any
uninitialized data.
Fixes#19462
Signed-off-by: David Goulet <dgoulet@torproject.org>
base16_decodes() now returns the number of decoded bytes. It's interface
changes from returning a "int" to a "ssize_t". Every callsite now checks the
returned value.
Fixes#14013
Signed-off-by: David Goulet <dgoulet@torproject.org>
realloc()ing a thing in order to try to save memory on it just
doesn't make sense with today's allocators. Instead, let's use the
fact that whenever we decompress something, either it isn't too big,
or we chop it up, or we reallocate it.
zlib 1.2 came out in 2003; earlier versions should be dead by now.
Our workaround code was only preventing us from using the gzip
encoding (if we decide to do so), and having some dead code linger
around in torgzip.c
The Autoconf macro AC_USE_SYSTEM_EXTENSIONS defines preprocessor macros
which turn on extensions to C and POSIX. The macro also makes it easier
for developers to use the extensions without needing (or forgetting) to
define them manually.
The macro can be safely used because it was introduced in Autoconf 2.60
and Tor requires Autoconf 2.63 and above.
There's accessors to get at things, but it ends up being rather
cumbersome. The only place where behavior should change is that the
code will fail instead of attempting to generate a new DH key if our
internal sanity check fails.
Like the previous commit, this probably breaks snapshots prior to pre5.
Instead of `ERR_remove_thread_state()` having a modified prototype, it
now has the old prototype and a deprecation annotation. Since it's
pointless to add extra complexity just to remain compatible with an old
OpenSSL development snapshot, update the code to work with 1.1.0pre5
and later.
This is a big-ish patch, but it's very straightforward. Under this
clang warning, we're not actually allowed to have a global variable
without a previous extern declaration for it. The cases where we
violated this rule fall into three roughly equal groups:
* Stuff that should have been static.
* Stuff that was global but where the extern was local to some
other C file.
* Stuff that was only global when built for the unit tests, that
needed a conditional extern in the headers.
The first two were IMO genuine problems; the last is a wart of how
we build tests.
This warning, IIUC, means that the compiler doesn't like it when it
sees a NULL check _after_ we've already dereferenced the
variable. In such cases, it considers itself free to eliminate the
NULL check.
There are a couple of tricky cases:
One was the case related to the fact that tor_addr_to_in6() can
return NULL if it gets a non-AF_INET6 address. The fix was to
create a variant which asserts on the address type, and never
returns NULL.
So, back long ago, XXX012 meant, "before Tor 0.1.2 is released, we
had better revisit this comment and fix it!"
But we have a huge pile of such comments accumulated for a large
number of released versions! Not cool.
So, here's what I tried to do:
* 0.2.9 and 0.2.8 are retained, since those are not yet released.
* XXX+ or XXX++ or XXX++++ or whatever means, "This one looks
quite important!"
* The others, after one-by-one examination, are downgraded to
plain old XXX. Which doesn't mean they aren't a problem -- just
that they cannot possibly be a release-blocking problem.
There are a few places where we want to disable a warning: for
example, when it's impossible to call a legacy API without
triggering it, or when it's impossible to include an external header
without triggering it.
This pile of macros uses GCC's c99 _Pragma support, plus the usual
macro trickery, to enable and disable warnings.
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.
