This defense will cause Cisco, Juniper, Fortinet, and other routers operating
in the default configuration to collapse netflow records that would normally
be split due to the 15 second flow idle timeout.
Collapsing these records should greatly reduce the utility of default netflow
data for correlation attacks, since all client-side records should become 30
minute chunks of total bytes sent/received, rather than creating multiple
separate records for every webpage load/ssh command interaction/XMPP chat/whatever
else happens to be inactive for more than 15 seconds.
The defense adds consensus parameters to govern the range of timeout values
for sending padding packets, as well as for keeping connections open.
The defense only sends padding when connections are otherwise inactive, and it
does not pad connections used solely for directory traffic at all. By default
it also doesn't pad inter-relay connections.
Statistics on the total padding in the last 24 hours are exported to the
extra-info descriptors.
Instead of returning 404 error code, this led to a NULL pointer being used and
thus a crash of tor.
Fixes#21471
Signed-off-by: David Goulet <dgoulet@torproject.org>
Fixes bug 20894; bugfix on 0.2.0.16-alpha.
We already applied a workaround for this as 20834, so no need to
freak out (unless you didn't apply 20384 yet).
This should be "impossible" without making a SHA1 collision, but
let's not keep the assumption that SHA1 collisions are super-hard.
This prevents another case related to 21278. There should be no
behavioral change unless -ftrapv is on.
I think this one probably can't underflow, since the input ranges
are small. But let's not tempt fate.
This patch also replaces the "cmp" functions here with just "eq"
functions, since nothing actually checked for anything besides 0 and
nonzero.
Related to 21278.
Fix for TROVE-2017-001 and bug 21278.
(Note: Instead of handling signed ints "correctly", we keep the old
behavior, except for the part where we would crash with -ftrapv.)
