We didn't really have test coverage for these parsing functions, so
I went and made some. These tests also verify that the parsing
functions set the list of invalid digests correctly.
One pain point in evolving the Tor design and implementing has been
adding code that makes clients reject directory documents that they
previously would have accepted, if those descriptors actually exist.
When this happened, the clients would get the document, reject it,
and then decide to try downloading it again, ad infinitum. This
problem becomes particularly obnoxious with authorities, since if
some authorities accept a descriptor that others don't, the ones
that don't accept it would go crazy trying to re-fetch it over and
over. (See for example ticket #9286.)
This patch tries to solve this problem by tracking, if a descriptor
isn't parseable, what its digest was, and whether it is invalid
because of some flaw that applies to the portion containing the
digest. (This excludes RSA signature problems: RSA signatures
aren't included in the digest. This means that a directory
authority can still put another directory authority into a loop by
mentioning a descriptor, and then serving that descriptor with an
invalid RSA signatures. But that would also make the misbehaving
directory authority get DoSed by the server it's attacking, so it's
not much of an issue.)
We already have a mechanism to mark something undownloadable with
downloadstatus_mark_impossible(); we use that here for
microdescriptors, extrainfos, and router descriptors.
Unit tests to follow in another patch.
Closes ticket #11243.
Fixes bug 13295; bugfix on 0.2.5.3-alpha.
The alternative here is to call crypto_global_init() from tor-resolve,
but let's avoid linking openssl into tor-resolve for as long as we
can.
When a spawned process forks, fails, then exits very quickly, (this
typically occurs when exec fails), there is a race condition between the
SIGCHLD handler updating the process_handle's fields, and checking the
process status in those fields. The update can occur before or after the
spawn tests check the process status.
We check whether the process is running or not running (rather than just
checking if it is running) to avoid this issue.
In circuit_build_times_calculate_timeout() in circuitstats.c, avoid dividing
by zero in the pareto calculations.
If either the alpha or p parameters are 0, we would divide by zero, yielding
an infinite result; which would be clamped to INT32_MAX anyway. So rather
than dividing by zero, we just skip the offending calculation(s), and
use INT32_MAX for the result.
Division by zero traps under clang -fsanitize=undefined-trap -fsanitize-undefined-trap-on-error.
Avoid 4 null pointer errors under clang shallow analysis (the default when
building under Xcode) by using tor_assert() to prove that the pointers
aren't null. Resolves issue 13284 via minor code refactoring.
This helps us avoid undefined behavior. It's based on a patch from teor,
except that I wrote a perl script to regenerate the patch:
#!/usr/bin/perl -p -w -i
BEGIN { %vartypes = (); }
if (/^[{}]/) {
%vartypes = ();
}
if (/^ *crypto_int(\d+) +([a-zA-Z_][_a-zA-Z0-9]*)/) {
$vartypes{$2} = $1;
} elsif (/^ *(?:signed +)char +([a-zA-Z_][_a-zA-Z0-9]*)/) {
$vartypes{$1} = '8';
}
# This fixes at most one shift per line. But that's all the code does.
if (/([a-zA-Z_][a-zA-Z_0-9]*) *<< *(\d+)/) {
$v = $1;
if (exists $vartypes{$v}) {
s/$v *<< *(\d+)/SHL$vartypes{$v}($v,$1)/;
}
}
# remove extra parenthesis
s/\(SHL64\((.*)\)\)/SHL64\($1\)/;
s/\(SHL32\((.*)\)\)/SHL32\($1\)/;
s/\(SHL8\((.*)\)\)/SHL8\($1\)/;
There are some loops of the form
for (i=1;i<1;++i) ...
And of course, if the loop index is initialized to 1, it will never
be less than 1, and the loop body will never be executed. This
upsets coverity.
Patch fixes CID 1221543 and 1221542
This bug shouldn't be reachable so long as secret_to_key_len and
secret_to_key_make_specifier stay in sync, but we might screw up
someday.
Found by coverity; this is CID 1241500
Bugfix on ed8f020e205267e6270494634346ab68d830e1d8; bug not in any
released version of Tor. Found by Coverity; this is CID 1239290.
[Yes, I used this commit message before, in 58e813d0fc.
Turns out, that fix wasn't right, since I didn't look up a
screen. :P ]
When size_t is the most memory you can have, make sure that things
referring to real parts of memory are size_t, not uint64_t or off_t.
But not on any released Tor.
Also, use it to generate test vectors, and add those test vectors
to test_crypto.c
This is based on ed25519.py from the ed25519 webpage; the kludgy hacks
are my own.
