Padding circuits were regular cells that got closed before their padding
machine could finish. This means that they can still receive regular cells from
their past life, but they have no way or reason to answer them anymore. Hence
let's ignore them before they even get to the proper subsystems.
Padding circuits were regular cells that got closed before their padding
machine could finish. This means that they can still receive regular cells from
their past life, but they have no way or reason to answer them anymore. Hence
let's ignore them before they even get to the proper subsystems.
Coverity doesn't understand that if begin_cell_parse() returns 0 and
sets is_begindir to 0, its address field will always be set.
Fixes bug 30126; bugfix on 0.2.4.7-alpha; Fixes CID 1447296.
This is to avoid having two sendme.{c|h} in the repository since the subsystem
is implemented in src/core/or/sendme.{c|h}.
Fixes#30769
Signed-off-by: David Goulet <dgoulet@torproject.org>
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.
Leave the other rend and hs_ident data around until circuit free, since code
may still try to inspect it after marking the circuit for close. The
circuitmap is the important thing to clean up, since repurposed
intropoints must be removed from this map to ensure validity.
If "Log debug ..." is not set, the decrement never happens. This lead to the
package/deliver window to be out of sync at the stream level and thus breaking
the connection after 50+ cells.
Fixes#30628
Signed-off-by: David Goulet <dgoulet@torproject.org>
Previously, we were looking at our global settings to see what kind
of proxy we had. But doing this would sometimes give us the wrong
results when we had ClientTransportPlugin configured but we weren't
using it for a particular connection. In several places in the
code, we had added checks to see if we were _really_ using a PT or
whether we were using a socks proxy, but we had forgotten to do so
in at least once case. Instead, since every time we call this
function we are asking about a single connection, it is probably
best just to make this function connection-specific.
Fixes bug 29670; bugfix on 0.2.6.2-alpha.
When we repurpose a hidden service circuit, we need to clean up from the HS
circuit map and any HS related data structured contained in the circuit.
This commit adds an helper function that does it when repurposing a hidden
service circuit.
Fixes#29034
Signed-off-by: David Goulet <dgoulet@torproject.org>
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.
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>
Turns out that we were only recording the "b_digest" but to have
bidirectionnal authenticated SENDMEs, we need to use the "f_digest" in the
forward cell situation.
Because of the cpath refactoring, this commit plays with the crypt_path_ and
relay_crypto_t API a little bit in order to respect the abstractions.
Previously, we would record the cell digest as the SENDME digest in the
decrypt cell function but to avoid code duplication (both directions needs to
record), we now do that right after iff the cell is recognized (at the edge).
It is now done in circuit_receive_relay_cell() instead.
We now also record the cell digest as the SENDME digest in both relay cell
encryption functions since they are split depending on the direction.
relay_encrypt_cell_outbound() and relay_encrypt_cell_inbound() need to
consider recording the cell digest depending on their direction (f vs b
digest).
Fixes#30428
Signed-off-by: David Goulet <dgoulet@torproject.org>
There was a missing cell version check against our max supported version. In
other words, we do not fallback to v0 anymore in case we do know the SENDME
version.
We can either handle it or not, never fallback to the unauthenticated version
in order to avoid gaming the authenticated logic.
Add a unit tests making sure we properly test that and also test that we can
always handle the default emit and accepted versions.
Fixes#30428
Signed-off-by: David Goulet <dgoulet@torproject.org>
The validation of the SENDME cell is now done as the very first thing when
receiving it for both client and exit. On failure to validate, the circuit is
closed as detailed in the specification.
Part of #30428
Signed-off-by: David Goulet <dgoulet@torproject.org>
It turns out that only the exit side is validating the authenticated SENDME v1
logic and never the client side. Which means that if a client ever uploaded
data towards an exit, the authenticated SENDME logic wouldn't apply.
For this to work, we have to record the cell digest client side as well which
introduced a new function that supports both type of edges.
This also removes a test that is not valid anymore which was that we didn't
allow cell recording on an origin circuit (client).
Part of #30428
Signed-off-by: David Goulet <dgoulet@torproject.org>
