Commit Graph

22375 Commits

Author SHA1 Message Date
Nick Mathewson
a3ec811c2e Merge branch 'maint-0.2.8' 2016-05-25 09:27:47 -04:00
Nick Mathewson
fdfc528f85 Merge branch 'bug19152_024_v2' into maint-0.2.8 2016-05-25 09:26:45 -04:00
Nick Mathewson
c4c4380a5e Fix a dangling pointer issue in our RSA keygen code
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.
2016-05-25 09:23:57 -04:00
Nick Mathewson
6abceca182 Merge branch 'memarea_overflow_027_squashed' into maint-0.2.8 2016-05-25 09:22:02 -04:00
Nick Mathewson
be2d37ad3c Fix a pointer arithmetic bug in memarea_alloc()
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.
2016-05-25 09:20:37 -04:00
Nick Mathewson
0ef36626ea Use calloc, not malloc(a*b), in ed25519 batch signature check fn
[Not a triggerable bug unless somebody is going to go checking
millions+ of signatures in a single go.]
2016-05-25 08:59:08 -04:00
Nick Mathewson
be3875cda2 Make sure that libscrypt_scrypt actually exists before using it.
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.
2016-05-24 10:31:02 -04:00
Nick Mathewson
771ca7c544 Stop recommending --enable-gcc-warnings in doc/HACKING 2016-05-23 14:40:27 -04:00
Nick Mathewson
2fa7a3af4c Make advisory-warnings on by default.
Add --enable-fatal-warnings to control -Werror.

Closes ticket 19044.
2016-05-23 14:39:56 -04:00
Nick Mathewson
5b7d4b0cea Merge branch 'maint-0.2.8' 2016-05-23 11:06:32 -04:00
cypherpunks
87134db57c Do not ignore files that are being tracked by git 2016-05-23 11:02:15 -04:00
Nick Mathewson
b53a2059c4 Expose crypto_digest_algorithm_get_length from crypto.c
Also, use it in routerparse.c
2016-05-23 10:58:27 -04:00
Nick Mathewson
2a884926c0 Merge remote-tracking branch 'dgoulet/bug19066_029_01' 2016-05-23 10:45:13 -04:00
Nick Mathewson
9c7edb0f3e Merge branch 'maint-0.2.8' 2016-05-20 10:46:50 -04:00
Nick Mathewson
33ffeab694 Changes file for previous commit 2016-05-20 08:36:15 -04:00
cypherpunks
0e20d056e9 Prevent ASAN from registering a SIGSEGV handler
AddressSanitizer's (ASAN) SIGSEGV handler overrides the backtrace
handler and prevents it from printing its backtrace. The output of ASAN
is different from what 'bt_test.py' expects and causes backtrace test
failures.

The 'allow_user_segv_handler' option allows applications to set their
own SIGSEGV handler but is not supported by older GCC versions. These
older GCC versions do support the 'handle_segv' which prevents ASAN from
setting its SIGSEGV handler.
2016-05-20 08:34:18 -04:00
Nick Mathewson
22eed6dec2 Whoops. We use -Wmussing-prototypes. 2016-05-20 08:29:26 -04:00
Nick Mathewson
acc083b520 Make another variable unsigned. 2016-05-20 08:12:09 -04:00
Nick Mathewson
50cbf22099 Fix a bug related to moving signing_key_cert
Now that the field exists in signed_descriptor_t, we need to make
sure we free it when we free a signed_descriptor_t, and we need to
make sure that we don't free it when we convert a routerinfo_t to a
signed_descriptor_t.

But not in any released Tor. I found this while working on #19128.

One problem: I don't see how this could cause 19128.
2016-05-20 07:59:09 -04:00
Nick Mathewson
f2205071f0 Remove round_int64_to_next_multiple_of: It is now unused. 2016-05-19 21:21:24 -04:00
Nick Mathewson
2775dd8649 Compute HS stats outputs without round_int64_...
Fix for bug 19130.
2016-05-19 21:21:24 -04:00
Nick Mathewson
60ac07940f Fix "conditional "ADD_MULODI4" was never defined". 2016-05-19 16:38:24 -04:00
Nick Mathewson
dcc4fd4403 Merge branch 'maint-0.2.8' 2016-05-19 16:05:13 -04:00
Nick Mathewson
33841a6030 Merge remote-tracking branch 'teor/fix18809-warnings' into maint-0.2.8 2016-05-19 16:04:56 -04:00
Nick Mathewson
649785d464 Merge branch 'link_ftrapv_clang32' 2016-05-19 16:01:35 -04:00
Nick Mathewson
ae7e2b9a7c add missing atoi for cosmetic reasons 2016-05-19 16:01:25 -04:00
Nick Mathewson
4a14c2cfc7 Merge branch 'maint-0.2.8' 2016-05-19 15:56:39 -04:00
Nick Mathewson
0d6f293e0e Merge remote-tracking branch 'public/bug19073' into maint-0.2.8 2016-05-19 15:56:31 -04:00
teor (Tim Wilson-Brown)
2d21f03cdc
Fix unused-but-set-variable warnings in the connection unit tests
No behaviour change - just remove the variables
2016-05-19 12:49:36 -04:00
teor (Tim Wilson-Brown)
c5d87ef6af
Describe what happens when we get a consensus, but no certificates
Comment-only change
2016-05-19 12:35:09 -04:00
Nick Mathewson
dd17df2253 lintchanges on 18809, and fix the bug number 2016-05-19 08:54:19 -04:00
Nick Mathewson
a7a44f2db0 Merge branch 'maint-0.2.8' 2016-05-19 08:29:58 -04:00
Nick Mathewson
7c7d990704 changelog typo fix 2016-05-19 08:29:45 -04:00
Nick Mathewson
06803c317f Fix a compilation error in test_dir.c 2016-05-19 08:27:11 -04:00
Nick Mathewson
d718c717a6 Merge branch 'maint-0.2.8' 2016-05-19 08:25:12 -04:00
Nick Mathewson
9f217c83b0 Merge branch 'bug18809_028_squashed' into maint-0.2.8 2016-05-19 08:17:02 -04:00
teor (Tim Wilson-Brown)
f698b509d8 Add unit tests for networkstatus_consensus_is_bootstrapping 2016-05-19 07:58:41 -04:00
teor (Tim Wilson-Brown)
d5c70d7102 Restore and improve download schedule unit tests 2016-05-19 07:58:41 -04:00
teor (Tim Wilson-Brown)
4254d0297c Update unit tests for multiple bootstrap connections 2016-05-19 07:58:41 -04:00
teor (Tim Wilson-Brown)
ab0a7e2961 Remove consensus_max_download_tries by refactoring
No behaviour change

This function is used twice. The code is simpler if we split
it up and inline it where it is used.
2016-05-19 07:58:40 -04:00
teor (Tim Wilson-Brown)
8dc8d71226 Changes file for bug 18809 2016-05-19 07:58:40 -04:00
teor (Tim Wilson-Brown)
84ab26c320 Stop downloading consensuses when a consensus has been downloaded
Previosuly, during bootstrap, we would continue to download
consensuses if we had a consensus, but didn't have the certificates
to validate it.
2016-05-19 07:58:40 -04:00
Nick Mathewson
6d6c8287d5 Include __mulodi4 in libor_ctime when it fixes clang -m32 -ftrapv
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.
2016-05-18 09:50:38 -04:00
Nick Mathewson
33034600c2 Add __mulodi4 source to src/ext
We need to define this function when compiling with clang -m32 -ftrapv,
since otherwise we get link errors, since apparently some versions
of libclang_rt.builtins don't define a version of it that works? Or
clang doesn't know to look for it?

This definition is taken from the LLVM source at
  https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/builtins/mulodi4.c

I've also included the license (dual BSD-ish/MIT-ish).
2016-05-18 09:44:01 -04:00
Nick Mathewson
159ea7a88f Fix a bad sizeof() in test_crypto.c. Harmless. Spotted by coverity. 2016-05-18 08:29:13 -04:00
Nick Mathewson
2729f166cb whitespace fixes 2016-05-17 20:08:03 -04:00
Nick Mathewson
ab932cd7bf Remove duplicate siging_key_cert fields.
With the fix for #17150, I added a duplicate certificate here.  Here
I remove the original location in 0.2.8.  (I wouldn't want to do
that in 027, due to the amount of authority-voting-related code
drift.)

Closes 19073.
2016-05-17 20:04:16 -04:00
Nick Mathewson
a7f6e434be Merge branch 'maint-0.2.8' 2016-05-17 19:48:49 -04:00
Nick Mathewson
3f49474349 Merge branch 'bug17150_027_extra' into maint-0.2.8 2016-05-17 19:47:22 -04:00
Nick Mathewson
00f74e0372 Improve API of routerinfo_incompatible_with_extrainfo()
This API change makes it so that routerinfo_incompatible...() no
longer takes a routerinfo_t, so that it's obvious that it should
only look at fields from the signed_descriptor_t.

This change should prevent a recurrence of #17150.
2016-05-17 13:24:01 -04:00