Sebastian Hahn [Thu, 30 Dec 2010 18:54:13 +0000 (19:54 +0100)]
Sanity-check consensus param values
We need to make sure that the worst thing that a weird consensus param
can do to us is to break our Tor (and only if the other Tors are
reliably broken in the same way) so that the majority of directory
authorities can't pull any attacks that are worse than the DoS that
they can trigger by simply shutting down.
One of these worse things was the cbtnummodes parameter, which could
lead to heap corruption on some systems if the value was sufficiently
large.
This commit fixes this particular issue and also introduces sanity
checking for all consensus parameters.
Nick Mathewson [Mon, 10 Jan 2011 21:18:32 +0000 (16:18 -0500)]
Always nul-terminate the result passed to evdns_server_add_ptr_reply
In dnsserv_resolved(), we carefully made a nul-terminated copy of the
answer in a PTR RESOLVED cell... then never used that nul-terminated
copy. Ouch.
Surprisingly this one isn't as huge a security problem as it could be.
The only place where the input to dnsserv_resolved wasn't necessarily
nul-terminated was when it was called indirectly from relay.c with the
contents of a relay cell's payload. If the end of the payload was
filled with junk, eventdns.c would take the strdup() of the name [This
part is bad; we might crash there if the cell is in a bad part of the
stack or the heap] and get a name of at least length
495[*]. eventdns.c then rejects any name of length over 255, so the
bogus data would be neither transmitted nor altered.
[*] If the name was less than 495 bytes long, the client wouldn't
actually be reading off the end of the cell.
Nonetheless this is a reasonably annoying bug. Better fix it.
Found while looking at bug 2332, reported by doorss. Bugfix on
0.2.0.1-alpha.
Nick Mathewson [Wed, 12 Jan 2011 19:29:38 +0000 (14:29 -0500)]
Make our replacement INT32_MAX always signed
The C standard says that INT32_MAX is supposed to be a signed
integer. On platforms that have it, we get the correct
platform-defined value. Our own replacement, however, was
unsigned. That's going to cause a bug somewhere eventually.
Nick Mathewson [Mon, 10 Jan 2011 22:24:16 +0000 (17:24 -0500)]
Pull up more data when parsing socks messages
Previously, we only looked at up to 128 bytes. This is a bad idea
since socks messages can be at least 256+x bytes long. Now we look at
up to 512 bytes; this should be enough for 0.2.2.x to handle all valid
SOCKS messages. For 0.2.3.x, we can think about handling trickier
cases.
Nick Mathewson [Mon, 10 Jan 2011 21:18:32 +0000 (16:18 -0500)]
Always nul-terminate the result passed to evdns_server_add_ptr_reply
In dnsserv_resolved(), we carefully made a nul-terminated copy of the
answer in a PTR RESOLVED cell... then never used that nul-terminated
copy. Ouch.
Surprisingly this one isn't as huge a security problem as it could be.
The only place where the input to dnsserv_resolved wasn't necessarily
nul-terminated was when it was called indirectly from relay.c with the
contents of a relay cell's payload. If the end of the payload was
filled with junk, eventdns.c would take the strdup() of the name [This
part is bad; we might crash there if the cell is in a bad part of the
stack or the heap] and get a name of at least length
495[*]. eventdns.c then rejects any name of length over 255, so the
bogus data would be neither transmitted nor altered.
[*] If the name was less than 495 bytes long, the client wouldn't
actually be reading off the end of the cell.
Nonetheless this is a reasonably annoying bug. Better fix it.
Found while looking at bug 2332, reported by doorss. Bugfix on
0.2.0.1-alpha.
Nick Mathewson [Mon, 10 Jan 2011 17:12:11 +0000 (12:12 -0500)]
Impose maximum sizes on parsed objects
An object, you'll recall, is something between -----BEGIN----- and
-----END----- tags in a directory document. Some of our code, as
doorss has noted in bug 2352, could assert if one of these ever
overflowed SIZE_T_CEILING but not INT_MAX. As a solution, I'm setting
a maximum size on a single object such that neither of these limits
will ever be hit. I'm also fixing the INT_MAX checks, just to be sure.
Nick Mathewson [Sun, 9 Jan 2011 23:54:45 +0000 (18:54 -0500)]
Fix check for failed evdns request creation
When using libevent 2, we use evdns_base_resolve_*(). When not, we
fake evdns_base_resolve_*() using evdns_resolve_*().
Our old check was looking for negative values (like libevent 2
returns), but our eventdns.c code returns 1. This code makes the
check just test for nonzero.
Note that this broken check was not for _resolve_ failures or even for
failures to _launch_ a resolve: it was for failures to _create_ or
_encode_ a resolve request.
Nick Mathewson [Thu, 6 Jan 2011 18:29:36 +0000 (13:29 -0500)]
Notice a little faster if we're running out of virtual addresses
We were not decrementing "available" every time we did
++next_virtual_addr in addressmap_get_virtual_address: we left out the
--available when we skipped .00 and .255 addresses.
This didn't actually cause a bug in most cases, since the failure mode
was to keep looping around the virtual addresses until we found one,
or until available hit zero. It could have given you an infinite loop
rather than a useful message, however, if you said "VirtualAddrNetwork
127.0.0.255/32" or something broken like that.
Nick Mathewson [Wed, 5 Jan 2011 21:02:43 +0000 (16:02 -0500)]
Fix a double-counting bug in addrmap_get_virtual_address
We were decrementing "available" twice for each in-use address we ran
across. This would make us declare that we ran out of virtual
addresses when the address space was only half full.
Nick Mathewson [Mon, 3 Jan 2011 17:42:19 +0000 (12:42 -0500)]
Never include pthread.h when building for Windows.
On Windows, we never use pthreads, since it doesn't usually exist,
and when it does it tends to be a little weirdly-behaved. But some
mingw installations have a pthreads installed, so autoconf detects
pthread.h and tells us about it. This would make us include
pthread.h, which could make for trouble when the iffy pthread.h
tried to include config.h.
This patch changes compat.h so that we never include pthread.h on
Windows. Fixes bug 2313; bugfix on 0.1.0.1-rc.
Nick Mathewson [Mon, 13 Dec 2010 23:40:21 +0000 (18:40 -0500)]
Have all of our allocation functions and a few others check for underflow
It's all too easy in C to convert an unsigned value to a signed one,
which will (on all modern computers) give you a huge signed value. If
you have a size_t value of size greater than SSIZE_T_MAX, that is way
likelier to be an underflow than it is to be an actual request for
more than 2gb of memory in one go. (There's nothing in Tor that
should be trying to allocate >2gb chunks.)
Nick Mathewson [Mon, 6 Dec 2010 17:01:32 +0000 (12:01 -0500)]
Fix a bug in calculating wakeup time on 64-bit machines.
If you had TIME_MAX > INT_MAX, and your "time_to_exhaust_bw =
accountingmax/expected_bandwidth_usage * 60" calculation managed to
overflow INT_MAX, then your time_to_consider value could underflow and
wind up being rediculously low or high. "Low" was no problem;
negative values got caught by the (time_to_consider <= 0) check.
"High", however, would get you a wakeup time somewhere in the distant
future.
The fix is to check for time_to_exhaust_bw overflowing INT_MAX, not
TIME_MAX: We don't allow any accounting interval longer than a month,
so if time_to_exhaust_bw is significantly larger than 31*24*60*60, we
can just clip it.
This is a bugfix on 0.0.9pre6, when accounting was first introduced.
It fixes bug 2146, unless there are other causes there too. The fix
is from boboper. (I tweaked it slightly by removing an assignment
that boboper marked as dead, and lowering a variable that no longer
needed to be function-scoped.)
Nick Mathewson [Mon, 6 Dec 2010 16:36:01 +0000 (11:36 -0500)]
Add a missing ! to directory_fetches_from_authorities
The old logic would have us fetch from authorities if we were refusing
unknown exits and our exit policy was reject*. Instead, we want to
fetch from authorities if we're refusing unknown exits and our exit
policy is _NOT_ reject*.
Fixed by boboper. Fixes more of 2097. Bugfix on 0.2.2.16-alpha.
Nick Mathewson [Fri, 3 Dec 2010 18:37:13 +0000 (13:37 -0500)]
Don't crash when accountingmax is set in non-server Tors
We use a hash of the identity key to seed a prng to tell when an
accounting period should end. But thanks to the bug998 changes,
clients no longer have server-identity keys to use as a long-term seed
in accounting calculations. In any case, their identity keys (as used
in TLS) were never never fixed. So we can just set the wakeup time
from a random seed instead there. Still open is whether everybody
should be random.
This patch fixes bug 2235, which was introduced in 0.2.2.18-alpha.
Correct information about support for guards being called helper nodes.
The spec stated that support for the helper-nodes command would be removed
in 0.1.3.x, however support for this command is still in Tor. Updated the spec
to reflect this and added a node that the command is deprecated.
Correct grammars to reflect that VERBOSE_NAMES is part of the protocol.
Several updates to grammars for events and GETINFO results. All relate
to the fact that LongName has replaced ServerID since 0.2.2.1-alpha. See
documentation of VERBOSE_NAMES for more information. The following
grammars were changed:
* orconn-status GETINFO result
* entry-guards GETINFO result
* Path general token
* OR Connection status changed event
* New descriptors available event
In all cases a note was added about when the old grammar applies.
Several changes to the way tokens describing servers are documented.
(1) Made the wording of the comments consistant with token names.
Digest/Fingerprint and Name/Nickname were being used interchangeably.
Better to just use Fingerprint and Nickname becuase they are the names
of the tokens.
(2) Places the tokens currently in use before the tokens used in older
versions. ServerSpec should be documented before ServerID.
(3) Added a note to the comments about ServerID that cross reference
the VERBOSE_FEATURE, allowing users to see when and why ServerID was
replaced with LongName.
(1) On by default is a bad way to describe features. Rather, they
are always on and should be viewed as a part of the control
protocol. Updated the wording in USEFEATURE to reflect this.
(2) Made descriptions of Tor versions consistant across all
features. There is the version in which a feature was introduced and
the version in which it became part of the protocol.
(3) Reworded the description of the VERBOSE_NAMES feature. The
previous wording describes the way things used to be first. Better to
lead with the current state of things and then describe how it differs
from old versions.