Fixes bug 4259, bugfix on 0.2.2.25-alpha. Bugfix by "Tey'".
Original message by submitter:
Changing nodes restrictions using a controller while Tor is doing
DNS resolution could makes Tor crashes (on WinXP at least). The
problem can be repeated by trying to reach a non-existent domain
using Tor:
curl --socks4a 127.0.0.1:9050 inexistantdomain.ext
.. and changing the ExitNodes parameter through the control port
before Tor returns a DNS resolution error (of course, the following
command won't work directly if the control port is password
protected):
echo SETCONF ExitNodes=TinyTurtle | nc -v 127.0.0.1 9051
Using a non-existent domain is needed to repeat the issue so that
Tor takes a few seconds for resolving the domain (which allows us to
change the configuration). Tor will crash while processing the
configuration change.
The bug is located in the addressmap_clear_excluded_trackexithosts
method which iterates over the entries of the addresses map in order
to check whether the changes made to the configuration will impact
those entries. When a DNS resolving is in progress, the new_adress
field of the associated entry will be set to NULL. The method
doesn't expect this field to be NULL, hence the crash.
The issue was that we overlooked the possibility of reverse DNS success
at the end of connection_ap_handshake_socks_resolved(). Issue discovered
by katmagic, thanks!
This patch introduces a few new functions in router.c to produce a
more helpful description of a node than its nickame, and then tweaks
nearly all log messages taking a nickname as an argument to call these
functions instead.
There are a few cases where I left the old log messages alone: in
these cases, the nickname was that of an authority (whose nicknames
are useful and unique), or the message already included an identity
and/or an address. I might have missed a couple more too.
This is a fix for bug 3045.
Previously, if they changed in torrc during a SIGHUP, all was well,
since we would just clear all transient entries from the addrmap
thanks to bug 1345. But if you changed them from the controller, Tor
would leave old mappings in place.
The VirtualAddrNetwork bug has been here since 0.1.1.19-rc; the
AutomapHosts* bug has been here since 0.2.0.1-alpha.
This bug couldn't happen when TrackExitHosts changed in torrc, since
the SIGHUP to reload the torrc would clear out all the transient
addressmap entries before. But if you used SETCONF to change
TrackExitHosts, old entries would be left alone: that's a bug, and so
this is a bugfix on Tor 0.1.0.1-rc.
Conflicts throughout. All resolved in favor of taking HEAD and
adding tor_mem* or fast_mem* ops as appropriate.
src/common/Makefile.am
src/or/circuitbuild.c
src/or/directory.c
src/or/dirserv.c
src/or/dirvote.c
src/or/networkstatus.c
src/or/rendclient.c
src/or/rendservice.c
src/or/router.c
src/or/routerlist.c
src/or/routerparse.c
src/or/test.c
Here I looked at the results of the automated conversion and cleaned
them up as follows:
If there was a tor_memcmp or tor_memeq that was in fact "safe"[*] I
changed it to a fast_memcmp or fast_memeq.
Otherwise if there was a tor_memcmp that could turn into a
tor_memneq or tor_memeq, I converted it.
This wants close attention.
[*] I'm erring on the side of caution here, and leaving some things
as tor_memcmp that could in my opinion use the data-dependent
fast_memcmp variant.
Previously, it would remove every trackhostexits-derived mapping
*from* xyz.<exitname>.exit; it was supposed to remove every
trackhostexits-derived mapping *to* xyz.<exitname>.exit.
Bugfix on 0.2.0.20-rc: fixes an XXX020 added while staring at bug-1090
issues.
Now we believe it to be the case that we never build a circuit for our
stream that has an unsuitable exit, so we'll never need to use such
a circuit. The risk is that we have some code that builds the circuit,
but now we refuse to use it, meaning we just build a bazillion circuits
and ignore them all.
IOW, if we were using TrackExitHosts, and we added an excluded node or
removed a node from exitnodes, we wouldn't actually remove the mapping
that points us at the new node.
Also, note with an XXX022 comment a place that I think we are looking
at the wrong string.
ExcludeExitNodes foo now means that foo.exit doesn't work. If
StrictNodes is set, then ExcludeNodes foo also overrides foo.exit.
foo.exit , however, still works even if foo is not listed in ExitNodes.
Since svn r1475/git 5b6099e8 in tor-0.0.6, we have responded to an
exhaustion of all 65535 stream IDs on a circuit by marking that
circuit for close. That's not the right response. Instead, we
should mark the circuit as "too dirty for new circuits".
Of course in reality this isn't really right either. If somebody
has managed to cram 65535 streams onto a circuit, the circuit is
probably not going to work well for any of those streams, so maybe
we should be limiting the number of streams on an origin circuit
concurrently.
Also, closing the stream in this case is probably the wrong thing to
do as well, but fixing that can also wait.
In afe414 (tor-0.1.0.1-rc~173), when we moved to
connection_edge_end_errno(), we used it in handling errors from
connection_connect(). That's not so good, since by the time
connection_connect() returns, the socket is no longer set, and we're
supposed to be looking at the socket_errno return value from
connection_connect() instead. So do what we should've done, and
look at the socket_errno value that we get from connection_connect().
Right now, we only consider sending stream-level SENDME cells when we
have completely flushed a connection_edge's outbuf, or when it sends
us a DATA cell. Neither of these is ideal for throughput.
This patch changes the behavior so we now call
connection_edge_consider_sending_sendme when we flush _some_ data from
an edge outbuf.
Fix for bug 2756; bugfix on svn r152.
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.
We were not decrementing "available" every time we did
++next_virtual_addr in addressmap_get_virtual_address: we left out the
--available when we skipped .00 and .255 addresses.
This didn't actually cause a bug in most cases, since the failure mode
was to keep looping around the virtual addresses until we found one,
or until available hit zero. It could have given you an infinite loop
rather than a useful message, however, if you said "VirtualAddrNetwork
127.0.0.255/32" or something broken like that.
Spotted by cypherpunks
We were decrementing "available" twice for each in-use address we ran
across. This would make us declare that we ran out of virtual
addresses when the address space was only half full.
https://trac.torproject.org/projects/tor/ticket/1859
Use router_get_by_digest() instead of router_get_by_hexdigest()
in circuit_discard_optional_exit_enclaves() and
rend_client_get_random_intro(), per Nick's comments.
Using router_get_by_digest() in rend_client_get_random_intro() will
break hidden services published by Tor versions pre 0.1.2.18 and
0.2.07-alpha as they only publish by nickname. This is acceptable
however as these versions only publish to authority tor26 and
don't work for versions in the 0.2.2.x series anyway.
https://trac.torproject.org/projects/tor/ticket/1859
There are two problems in this bug:
1. When an OP makes a .exit request specifying itself as the exit, and the exit
is not yet listed, Tor gets all the routerinfos needed for the circuit but
discovers in circuit_is_acceptable() that its own routerinfo is not in the
routerdigest list and cannot be used. Tor then gets locked in a cycle of
repeating these two steps. When gathering the routerinfos for a circuit,
specifically when the exit has been chosen by .exit notation, Tor needs to
apply the same rules it uses later on when deciding if it can build a
circuit with those routerinfos.
2. A different bug arises in the above situation when the Tor instance's
routerinfo *is* listed in the routerlist, it shares its nickname with a
number of other Tor nodes, and it does not have 'Named' rights to its
nickname.
So for example, if (i) there are five nodes named Bob in the network, (ii) I
am running one of them but am flagged as 'Unnamed' because someone else
claimed the 'Bob' nickname first, and (iii) I run my Tor as both client
and exit the following can happen to me:
- I go to www.evil.com
- I click on a link www.evil.com.bob.exit
- My request will exit through my own Tor node rather than the 'Named'
node Bob or any of the others.
- www.evil.com now knows I am actually browsing from the same computer
that is running my 'Bob' node
So to solve both issues we need to ensure:
- When fulfilling a .exit request we only choose a routerinfo if it exists in
the routerlist, even when that routerinfo is ours.
- When getting a router by nickname we only return our own router information
if it is not going to be used for building a circuit.
We ensure this by removing the special treatment afforded our own router in
router_get_by_nickname(). This means the function will only return the
routerinfo of our own router if it is in the routerlist built from authority
info and has a unique nickname or is bound to a non-unique nickname.
There are some uses of router_get_by_nickname() where we are looking for the
router by name because of a configuration directive, specifically local
declaration of NodeFamilies and EntryNodes and other routers' declaration of
MyFamily. In these cases it is not at first clear if we need to continue
returning our own routerinfo even if our router is not listed and/or has a
non-unique nickname with the Unnamed flag.
The patch treats each of these cases as follows:
Other Routers' Declaration of MyFamily
This happens in routerlist_add_family(). If another router declares our router
in its family and our router has the Unnamed flag or is not in the routerlist
yet, should we take advantage of the fact that we know our own routerinfo to
add us in anyway? This patch says 'no, treat our own router just like any
other'. This is a safe choice because it ensures our client has the same view
of the network as other clients. We also have no good way of knowing if our
router is Named or not independently of the authorities, so we have to rely on
them in this.
Local declaration of NodeFamilies
Again, we have no way of knowing if the declaration 'NodeFamilies
Bob,Alice,Ringo' refers to our router Bob or the Named router Bob, so we have
to defer to the authorities and treat our own router like any other.
Local declaration of NodeFamilies
Again, same as above. There's also no good reason we would want our client to
choose it's own router as an entry guard if it does not meet the requirements
expected of any other router on the network.
In order to reduce the possibility of error, the patch also replaces two
instances where we were using router_get_by_nickname() with calls to
router_get_by_hexdigest() where the identity digest of the router
is available.
https://trac.torproject.org/projects/tor/ticket/1859
Use router_get_by_digest() instead of router_get_by_hexdigest()
in circuit_discard_optional_exit_enclaves() and
rend_client_get_random_intro(), per Nick's comments.
Using router_get_by_digest() in rend_client_get_random_intro() will
break hidden services published by Tor versions pre 0.1.2.18 and
0.2.07-alpha as they only publish by nickname. This is acceptable
however as these versions only publish to authority tor26 and
don't work for versions in the 0.2.2.x series anyway.
https://trac.torproject.org/projects/tor/ticket/1859
There are two problems in this bug:
1. When an OP makes a .exit request specifying itself as the exit, and the exit
is not yet listed, Tor gets all the routerinfos needed for the circuit but
discovers in circuit_is_acceptable() that its own routerinfo is not in the
routerdigest list and cannot be used. Tor then gets locked in a cycle of
repeating these two steps. When gathering the routerinfos for a circuit,
specifically when the exit has been chosen by .exit notation, Tor needs to
apply the same rules it uses later on when deciding if it can build a
circuit with those routerinfos.
2. A different bug arises in the above situation when the Tor instance's
routerinfo *is* listed in the routerlist, it shares its nickname with a
number of other Tor nodes, and it does not have 'Named' rights to its
nickname.
So for example, if (i) there are five nodes named Bob in the network, (ii) I
am running one of them but am flagged as 'Unnamed' because someone else
claimed the 'Bob' nickname first, and (iii) I run my Tor as both client
and exit the following can happen to me:
- I go to www.evil.com
- I click on a link www.evil.com.bob.exit
- My request will exit through my own Tor node rather than the 'Named'
node Bob or any of the others.
- www.evil.com now knows I am actually browsing from the same computer
that is running my 'Bob' node
So to solve both issues we need to ensure:
- When fulfilling a .exit request we only choose a routerinfo if it exists in
the routerlist, even when that routerinfo is ours.
- When getting a router by nickname we only return our own router information
if it is not going to be used for building a circuit.
We ensure this by removing the special treatment afforded our own router in
router_get_by_nickname(). This means the function will only return the
routerinfo of our own router if it is in the routerlist built from authority
info and has a unique nickname or is bound to a non-unique nickname.
There are some uses of router_get_by_nickname() where we are looking for the
router by name because of a configuration directive, specifically local
declaration of NodeFamilies and EntryNodes and other routers' declaration of
MyFamily. In these cases it is not at first clear if we need to continue
returning our own routerinfo even if our router is not listed and/or has a
non-unique nickname with the Unnamed flag.
The patch treats each of these cases as follows:
Other Routers' Declaration of MyFamily
This happens in routerlist_add_family(). If another router declares our router
in its family and our router has the Unnamed flag or is not in the routerlist
yet, should we take advantage of the fact that we know our own routerinfo to
add us in anyway? This patch says 'no, treat our own router just like any
other'. This is a safe choice because it ensures our client has the same view
of the network as other clients. We also have no good way of knowing if our
router is Named or not independently of the authorities, so we have to rely on
them in this.
Local declaration of NodeFamilies
Again, we have no way of knowing if the declaration 'NodeFamilies
Bob,Alice,Ringo' refers to our router Bob or the Named router Bob, so we have
to defer to the authorities and treat our own router like any other.
Local declaration of NodeFamilies
Again, same as above. There's also no good reason we would want our client to
choose it's own router as an entry guard if it does not meet the requirements
expected of any other router on the network.
In order to reduce the possibility of error, the patch also replaces two
instances where we were using router_get_by_nickname() with calls to
router_get_by_hexdigest() where the identity digest of the router
is available.
The RefuseUnknownExits config option is now a tristate, with "1"
meaning "enable it no matter what the consensus says", "0" meaning
"disable it no matter what the consensus says", and "auto" meaning "do
what the consensus says". If the consensus is silent, we enable
RefuseUnknownExits.
This patch also changes the dirserv logic so that refuseunknownexits
won't make us cache unless we're an exit.
I'm going to use this to implement more fairness in
circuit_resume_edge_reading_helper in an attempt to fix bug 1298.
(Updated with fixes from arma and Sebastian)
