Make origin-side messages about padding negotiation failure into
LOG_PROTOCOL_WARN.
I'm not sure I like this either.. But the negotiation refusal case might
happen naturally due to consensus drift, and is functionally no different than
a corrupted cell.
This is necessary since shutting down libevent frees some pointer
that the subsystems want to free themselves. A longer term solution
will be to turn the evloop module into a subsystem itself, but for
now it is best to do the minimal fix.
Fixes bug 30629; bugfix on 0.4.1.1-alpha.
If tor is compiled on a system with neither vasprintf nor _vscprintf,
the fallback implementation exposes a logic flaw which prevents
proper usage of strings longer than 127 characters:
* tor_vsnprintf returns -1 if supplied buffer is not large enough,
but tor_vasprintf uses this function to retrieve required length
* the result of tor_vsnprintf is not properly checked for negative
return values
Both aspects together could in theory lead to exposure of uninitialized
stack memory in the resulting string. This requires an invalid format
string or data that exceeds integer limitations.
Fortunately tor is not even able to run with this implementation because
it runs into asserts early on during startup. Also the unit tests fail
during a "make check" run.
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
[backported to 0.2.9 by nickm]
Fixes assertion failure in tests on NetBSD:
slow/prob_distr/stochastic_log_logistic: [forking] May 25 03:56:58.091 [err] tor_assertion_failed_(): Bug: src/lib/crypt_ops/crypto_rand_fast.c:184: crypto_fast_rng_new_from_seed: Assertion inherit != INHERIT_RES_KEEP failed; aborting. (on Tor 0.4.1.1-alpha-dev 29955f13e5)
May 25 03:56:58.091 [err] Bug: Assertion inherit != INHERIT_RES_KEEP failed in crypto_fast_rng_new_from_seed at src/lib/crypt_ops/crypto_rand_fast.c:184: . (Stack trace not available) (on Tor 0.4.1.1-alpha-dev 29955f13e5)
[Lost connection!]
Proposal 289 prevents SENDME-flooding by requiring the other side to
authenticate the data it has received. But this data won't actually
be random if they are downloading a known resource. "No problem",
we said, "let's fell the empty parts of our cells with some
randomness!" and we did that in #26871.
Unfortunately, if the relay data payloads are all completely full,
there won't be any empty parts for us to randomize.
Therefore, we now pick random "randomness windows" between
CIRCWINDOW_INCREMENT/2 and CIRCWINDOW_INCREMENT. We remember whether we have
sent a cell containing at least 16 bytes of randomness in that window. If we
haven't, then when the window is exhausted, we send one. (This window approach
is designed to lower the number of rng checks we have to do. The number 16 is
pulled out of a hat to change the attacker's guessing difficulty to
"impossible".)
Implements 28646.
We added this facility so that we could get deterministic PRNG
behavior for coverage testing on tests that use a replaced PRNG.
We need to have our coverage determinism tool test for this as well.
Because it invokes the Tor mainloop, it does unpredictable things to
test coverage of a lot of code that it doesn't actually test at
all. (It is more an integration test than anything else.)
The ordinary definitions of timeradd() and timersub() contain a
branch. However, in coverage builds, this means that we get spurious
complaints about partially covered basic blocks, in a way that makes
our coverage determinism harder to check.
Ordinarily we skip calling log_fn(LOG_DEBUG,...) if debug logging is
completely disabled. However, in coverage builds, this means that
we get spurious complaints about partially covered basic blocks, in
a way that makes our coverage determinism harder to check.
Two non fatal asserts are added in this commit. First one is to see if the
SENDME digest list kept on the circuit for validation ever grows bigger than
the maximum number of expected SENDME on a circuit (currently 10).
The second one is to know if we ever send more than one SENDME at a time on a
circuit. In theory, we shouldn't but if we ever do, the v1 implementation
wouldn't work because we only keep one single cell digest (the previous cell
to the SENDME) on the circuit/cpath. Thus, sending two SENDME consecutively
will lead to a mismatch on the other side because the same cell digest would
be use and thus the circuit would collapse.
Finally, add an extra debug log in case we emit a v0 which also includes the
consensus emit version in that case.
Part of #30428
Signed-off-by: David Goulet <dgoulet@torproject.org>
We must not accumulate digests on the circuit if the other end point is using
another SENDME version that is not using those digests like v0.
This commit makes it that we always pop the digest regardless of the version.
Part of #30428
Signed-off-by: David Goulet <dgoulet@torproject.org>
Commit 4ef8470fa5480d3b was actually reverted before because in the end we
needed to do this minus 1 check on the window.
This commit clarifies that in the code, takes the useful comment changes from
4ef8470fa5480d3b and makes sendme_circuit_cell_is_next() private since it
behaves in a very specific way that one external caller might expect.
Part of #30428.
Signed-off-by: David Goulet <dgoulet@torproject.org>
