rransom notes correctly that now that we aren't checking our HSDir
flag, we have no actual reason to check whether we are listed in the
consensus at all when determining if we should act like a hidden
service directory.
The old behavior contributed to unreliability when hidden services and
hsdirs had different consensus versions, and so had different opinions
about who should be cacheing hsdir info.
Bugfix on 0.2.0.10-alpha; based on discussions surrounding bug 2732.
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.
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.
The routerset_equal function explicitly handles NULL inputs, so
there's no need to check inputs for NULL before calling it.
Also fix a bug in routerset_equal where a non-NULL routerset with no
entries didn't get counted as equal to a NULL routerset. This was
untriggerable, I think, but potentially annoying down the road.
If we're picking a random directory node, never pick an excluded one.
But if we've chosen a specific one (or all), allow it unless strictnodes
is set (in which case warn so the user knows it's their fault).
When warning that we won't connect to a strictly excluded node,
log what it was we were trying to do at that node.
When ExcludeNodes is set but StrictNodes is not set, we only use
non-excluded nodes if we can, but fall back to using excluded nodes
if none of those nodes is usable.
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)
Sebastian notes (and I think correctly) that one of our ||s should
have been an &&, which simplifies a boolean expression to decide
whether to replace bridges. I'm also refactoring out the negation at
the start of the expression, to make it more readable.
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.
In the case where old_router == NULL but sdmap has an entry for the
router, we can currently safely infer that the old_router was not a
bridge. Add an assert to ensure that this remains true, and fix the
logic not to die with the tor_assert(old_router) call.
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.
When picking bridges (or other nodes without a consensus entry (and
thus no bandwidth weights)) we shouldn't just trust the node's
descriptor. So far we believed anything between 0 and 10MB/s, where 0
would mean that a node doesn't get any use from use unless it is our
only one, and 10MB/s would be a quite siginficant weight. To make this
situation better, we now believe weights in the range from 20kB/s to
100kB/s. This should allow new bridges to get use more quickly, and
means that it will be harder for bridges to see almost all our traffic.
