Our regular DH parameters that we use for circuit and rendezvous
crypto are unchanged. This is yet another small step on the path of
protocol fingerprinting resistance.
(Backport from 0.2.2's 5ed73e3807)
We detect and reject said attempts if there is no chosen exit node or
circuit: connecting to a private addr via a randomly chosen exit node
will usually fail (if all exits reject private addresses), is always
ill-defined (you're not asking for any particular host or service),
and usually an error (you've configured all requests to go over Tor
when you really wanted to configure all _remote_ requests to go over
Tor).
This can also help detect forwarding loop requests.
Found as part of bug2279.
If we got a signed digest that was shorter than the required digest
length, but longer than 20 bytes, we would accept it as long
enough.... and then immediately fail when we want to check it.
Fixes bug 2409; bug in 0.2.2.20-alpha; found by piebeer.
When we added support for separate client tls certs on bridges in
a2bb0bfdd5 we forgot to correctly initialize this when changing
from relay to bridge or vice versa while Tor is running. Fix that
by always initializing keys when the state changes.
Fixes bug 2433.
Our regular DH parameters that we use for circuit and rendezvous
crypto are unchanged. This is yet another small step on the path of
protocol fingerprinting resistance.
This patch imposes (very long) limits on the length of a line in a
directory document, and on the length of a certificate. I don't
think it should actually be possible to overrun these remotely,
since we already impose a maximum size on any directory object we're
downloading, but a little defensive programming never hurt anybody.
Roger emailed me that doorss reported these on IRC, but nobody seems
to have put them on the bugtracker.
We need to make sure that the worst thing that a weird consensus param
can do to us is to break our Tor (and only if the other Tors are
reliably broken in the same way) so that the majority of directory
authorities can't pull any attacks that are worse than the DoS that
they can trigger by simply shutting down.
One of these worse things was the cbtnummodes parameter, which could
lead to heap corruption on some systems if the value was sufficiently
large.
This commit fixes this particular issue and also introduces sanity
checking for all consensus parameters.
Our public key functions assumed that they were always writing into a
large enough buffer. In one case, they weren't.
(Incorporates fixes from sebastian)
In dnsserv_resolved(), we carefully made a nul-terminated copy of the
answer in a PTR RESOLVED cell... then never used that nul-terminated
copy. Ouch.
Surprisingly this one isn't as huge a security problem as it could be.
The only place where the input to dnsserv_resolved wasn't necessarily
nul-terminated was when it was called indirectly from relay.c with the
contents of a relay cell's payload. If the end of the payload was
filled with junk, eventdns.c would take the strdup() of the name [This
part is bad; we might crash there if the cell is in a bad part of the
stack or the heap] and get a name of at least length
495[*]. eventdns.c then rejects any name of length over 255, so the
bogus data would be neither transmitted nor altered.
[*] If the name was less than 495 bytes long, the client wouldn't
actually be reading off the end of the cell.
Nonetheless this is a reasonably annoying bug. Better fix it.
Found while looking at bug 2332, reported by doorss. Bugfix on
0.2.0.1-alpha.
