This mistake causes two possible bugs. I believe they are both
harmless IRL.
BUG 1: memory stomping
When we call the memset, we are overwriting two 0 bytes past the end
of packed_cell_t.body. But I think that's harmless in practice,
because the definition of packed_cell_t is:
// ...
typedef struct packed_cell_t {
TOR_SIMPLEQ_ENTRY(packed_cell_t) next;
char body[CELL_MAX_NETWORK_SIZE];
uint32_t inserted_time;
} packed_cell_t;
So we will overwrite either two bytes of inserted_time, or two bytes
of padding, depending on how the platform handles alignment.
If we're overwriting padding, that's safe.
If we are overwriting the inserted_time field, that's also safe: In
every case where we call cell_pack() from connection_or.c, we ignore
the inserted_time field. When we call cell_pack() from relay.c, we
don't set or use inserted_time until right after we have called
cell_pack(). SO I believe we're safe in that case too.
BUG 2: memory exposure
The original reason for this memset was to avoid the possibility of
accidentally leaking uninitialized ram to the network. Now
remember, if wide_circ_ids is false on a connection, we shouldn't
actually be sending more than 512 bytes of packed_cell_t.body, so
these two bytes can only leak to the network if there is another bug
somewhere else in the code that sends more data than is correct.
Fortunately, in relay.c, where we allocate packed_cell_t in
packed_cell_new() , we allocate it with tor_malloc_zero(), which
clears the RAM, right before we call cell_pack. So those
packed_cell_t.body bytes can't leak any information.
That leaves the two calls to cell_pack() in connection_or.c, which
use stack-alocated packed_cell_t instances.
In or_handshake_state_record_cell(), we pass the cell's contents to
crypto_digest_add_bytes(). When we do so, we get the number of
bytes to pass using the same setting of wide_circ_ids as we passed
to cell_pack(). So I believe that's safe.
In connection_or_write_cell_to_buf(), we also use the same setting
of wide_circ_ids in both calls. So I believe that's safe too.
I introduced this bug with 1c0e87f6d8
back in 0.2.4.11-alpha; it is bug 22737 and CID 1401591
On an hidden service rendezvous circuit, a BEGIN_DIR could be sent
(maliciously) which would trigger a tor_assert() because
connection_edge_process_relay_cell() thought that the circuit is an
or_circuit_t but is an origin circuit in reality.
Fixes#22494
Reported-by: Roger Dingledine <arma@torproject.org>
Signed-off-by: David Goulet <dgoulet@torproject.org>
This fixes an assertion failure in relay_send_end_cell_from_edge_() when an
origin circuit and a cpath_layer = NULL were passed.
A service rendezvous circuit could do such a thing when a malformed BEGIN cell
is received but shouldn't in the first place because the service needs to send
an END cell on the circuit for which it can not do without a cpath_layer.
Fixes#22493
Reported-by: Roger Dingledine <arma@torproject.org>
Signed-off-by: David Goulet <dgoulet@torproject.org>
Whenever we rotate our TLS context, we change our Ed25519
Signing->Link certificate. But if we've already started a TLS
connection, then we've already sent the old X509 link certificate,
so the new Ed25519 Signing->Link certificate won't match it.
To fix this, we now store a copy of the Signing->Link certificate
when we initialize the handshake state, and send that certificate
as part of our CERTS cell.
Fixes one case of bug22460; bugfix on 0.3.0.1-alpha.
Previously we could sometimes change our signing key, but not
regenerate the certificates (signing->link and signing->auth) that
were signed with it. Also, we would regularly replace our TLS x.509
link certificate (by rotating our TLS context) but not replace our
signing->link ed25519 certificate. In both cases, the resulting
inconsistency would make other relays reject our link handshakes.
Fixes two cases of bug 22460; bugfix on 0.3.0.1-alpha.
The encrypted_data_length_is_valid() function wasn't validating correctly the
length of the encrypted data of a v3 descriptor. The side effect of this is
that an HSDir was rejecting the descriptor and ultimately not storing it.
Fixes#22447
Signed-off-by: David Goulet <dgoulet@torproject.org>
When directory authorities reject a router descriptor due to keypinning,
free the router descriptor rather than leaking the memory.
Fixes bug 22370; bugfix on 0.2.7.2-alpha.
We used to not set the guard state in launch_direct_bridge_descriptor_fetch().
So when a bridge descriptor fetch failed, the guard subsystem would never
learn about the fail (and hence the guard's reachability state would not
be updated).
