The socket already carries the net namespace with it so there is
no need to be passing another net around.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.

This makes the very common pattern of

  if (genlmsg_end(...) < 0) { ... }

be a whole bunch of dead code. Many places also simply do

  return nlmsg_end(...);

and the caller is expected to deal with it.

This also commonly (at least for me) causes errors, because it is very
common to write

  if (my_function(...))
    /* error condition */

and if my_function() does "return nlmsg_end()" this is of course wrong.

Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.

Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did

-	return nlmsg_end(...);
+	nlmsg_end(...);
+	return 0;

I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.

One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The patch c5adde94 ("netlink:
eliminate nl_sk_hash_lock") introduced a bug where the EADDRINUSE
error has been replaced by ENOMEM.  This patch rectifies that
problem.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As rhashtable_lookup_compare_insert() can guarantee the process
of search and insertion is atomic, it's safe to eliminate the
nl_sk_hash_lock. After this, object insertion or removal will
be protected with per bucket lock on write side while object
lookup is guarded with rcu read lock on read side.
Signed-off-by: NYing Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Defers the release of the socket reference using call_rcu() to
allow using an RCU read-side protected call to rhashtable_lookup()

This restores behaviour and performance gains as previously
introduced by e341694e ("netlink: Convert netlink_lookup() to use
RCU protected hash table") without the side effect of severely
delayed socket destruction.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduces an array of spinlocks to protect bucket mutations. The number
of spinlocks per CPU is configurable and selected based on the hash of
the bucket. This allows for parallel insertions and removals of entries
which do not share a lock.

The patch also defers expansion and shrinking to a worker queue which
allows insertion and removal from atomic context. Insertions and
deletions may occur in parallel to it and are only held up briefly
while the particular bucket is linked or unzipped.

Mutations of the bucket table pointer is protected by a new mutex, read
access is RCU protected.

In the event of an expansion or shrinking, the new bucket table allocated
is exposed as a so called future table as soon as the resize process
starts.  Lookups, deletions, and insertions will briefly use both tables.
The future table becomes the main table after an RCU grace period and
initial linking of the old to the new table was performed. Optimization
of the chains to make use of the new number of buckets follows only the
new table is in use.

The side effect of this is that during that RCU grace period, a bucket
traversal using any rht_for_each() variant on the main table will not see
any insertions performed during the RCU grace period which would at that
point land in the future table. The lookup will see them as it searches
both tables if needed.

Having multiple insertions and removals occur in parallel requires nelems
to become an atomic counter.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch is in preparation to introduce per bucket spinlocks. It
extends all iterator macros to take the bucket table and bucket
index. It also introduces a new rht_dereference_bucket() to
handle protected accesses to buckets.

It introduces a barrier() to the RCU iterators to the prevent
the compiler from caching the first element.

The lockdep verifier is introduced as stub which always succeeds
and properly implement in the next patch when the locks are
introduced.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hash the key inside of rhashtable_lookup_compare() like
rhashtable_lookup() does. This allows to simplify the hashing
functions and keep them private.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Cc: netfilter-devel@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Users can request to bind to arbitrary multicast groups, so warning
when the requested group number is out of range is not appropriate.

And with the warning removed, and the 'err' variable properly given
an initial value, we can remove 'found' altogether.
Reported-by: NSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Netlink families can exist in multiple namespaces, and for the most
part multicast subscriptions are per network namespace. Thus it only
makes sense to have bind/unbind notifications per network namespace.

To achieve this, pass the network namespace of a given client socket
to the bind/unbind functions.

Also do this in generic netlink, and there also make sure that any
bind for multicast groups that only exist in init_net is rejected.
This isn't really a problem if it is accepted since a client in a
different namespace will never receive any notifications from such
a group, but it can confuse the family if not rejected (it's also
possible to silently (without telling the family) accept it, but it
would also have to be ignored on unbind so families that take any
kind of action on bind/unbind won't do unnecessary work for invalid
clients like that.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In order to make the newly fixed multicast bind/unbind
functionality in generic netlink, pass them down to the
appropriate family.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, netlink_unbind() is only called when the socket
explicitly unbinds, which limits its usefulness (luckily
there are no users of it yet anyway.)

Call netlink_unbind() also when a socket is released, so it
becomes possible to track listeners with this callback and
without also implementing a netlink notifier (and checking
netlink_has_listeners() in there.)
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The code is now confusing to read - first in one function down
(netlink_remove) any group subscriptions are implicitly removed
by calling __sk_del_bind_node(), but the subscriber database is
only updated far later by calling netlink_update_listeners().

Move the latter call to just after removal from the list so it
is easier to follow the code.

This also enables moving the locking inside the kernel-socket
conditional, which improves the normal socket destruction path.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The new name is more expressive - this isn't a generic unbind
function but rather only a little undo helper for use only in
netlink_bind().
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Each mmap Netlink frame contains a status field which indicates
whether the frame is unused, reserved, contains data or needs to
be skipped. Both loads and stores may not be reordeded and must
complete before the status field is changed and another CPU might
pick up the frame for use. Use an smp_mb() to cover needs of both
types of callers to netlink_set_status(), callers which have been
reading data frame from the frame, and callers which have been
filling or releasing and thus writing to the frame.

- Example code path requiring a smp_rmb():
  memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, hdr->nm_len);
  netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);

- Example code path requiring a smp_wmb():
  hdr->nm_uid	= from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
  hdr->nm_gid	= from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
  netlink_frame_flush_dcache(hdr);
  netlink_set_status(hdr, NL_MMAP_STATUS_VALID);

Fixes: f9c228 ("netlink: implement memory mapped recvmsg()")
Reported-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Checking the file f_count and the nlk->mapped count is not completely
sufficient to prevent the mmap'd area contents from changing from
under us during netlink mmap sendmsg() operations.

Be careful to sample the header's length field only once, because this
could change from under us as well.

Fixes: 5fd96123 ("netlink: implement memory mapped sendmsg()")
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NDaniel Borkmann <dborkman@redhat.com>
Acked-by: NThomas Graf <tgraf@suug.ch>

For netlink, we shouldn't be using arch_fast_hash() as a hashing
discipline, but rather jhash() instead.

Since netlink sockets can be opened by any user, a local attacker
would be able to easily create collisions with the DPDK-derived
arch_fast_hash(), which trades off performance for security by
using crc32 CPU instructions on x86_64.

While it might have a legimite use case in other places, it should
be avoided in netlink context, though. As rhashtable's API is very
flexible, we could later on still decide on other hashing disciplines,
if legitimate.

Reference: http://thread.gmane.org/gmane.linux.kernel/1844123
Fixes: e341694e ("netlink: Convert netlink_lookup() to use RCU protected hash table")
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Acked-by: NThomas Graf <tgraf@suug.ch>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Note that the code _using_ ->msg_iter at that point will be very
unhappy with anything other than unshifted iovec-backed iov_iter.
We still need to convert users to proper primitives.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The __module_get() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Reallocation is only required for shrinking and expanding and both rely
on a mutex for synchronization and callers of rhashtable_init() are in
non atomic context. Therefore, no reason to continue passing allocation
hints through the API.

Instead, use GFP_KERNEL and add __GFP_NOWARN | __GFP_NORETRY to allow
for silent fall back to vzalloc() without the OOM killer jumping in as
pointed out by Eric Dumazet and Eric W. Biederman.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently mutex_is_held can only test locks in the that are global
since it takes no arguments.  This prevents rhashtable from being
used in places where locks are lock, e.g., per-namespace locks.

This patch adds a parent field to mutex_is_held and rhashtable_params
so that local locks can be used (and tested).
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The rhashtable function mutex_is_held is only used when PROVE_LOCKING
is enabled.  This patch modifies netlink so that we can rhashtable.h
itself can later make mutex_is_held optional depending on PROVE_LOCKING.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Even if netlink_kernel_cfg::unbind is implemented the unbind() method is
not called, because cfg->unbind is omitted in __netlink_kernel_create().
And fix wrong argument of test_bit() and off by one problem.

At this point, no unbind() method is implemented, so there is no real
issue.

Fixes: 4f520900 ("netlink: have netlink per-protocol bind function return an error code.")
Signed-off-by: NHiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Cc: Richard Guy Briggs <rgb@redhat.com>
Acked-by: NRichard Guy Briggs <rgb@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This encapsulates all of the skb_copy_datagram_iovec() callers
with call argument signature "skb, offset, msghdr->msg_iov, length".

When we move to iov_iters in the networking, the iov_iter object will
sit in the msghdr.

Having a helper like this means there will be less places to touch
during that transformation.

Based upon descriptions and patch from Al Viro.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The synchronize_rcu() in netlink_release() introduces unacceptable
latency. Reintroduce minimal lookup so we can drop the
synchronize_rcu() until socket destruction has been RCUfied.

Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: NSteinar H. Gunderson <sgunderson@bigfoot.com>
Reported-and-tested-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

we used to check for "nobody else could start doing anything with
that opened file" by checking that refcount was 2 or less - one
for descriptor table and one we'd acquired in fget() on the way to
wherever we are.  That was race-prone (somebody else might have
had a reference to descriptor table and do fget() just as we'd
been checking) and it had become flat-out incorrect back when
we switched to fget_light() on those codepaths - unlike fget(),
it doesn't grab an extra reference unless the descriptor table
is shared.  The same change allowed a race-free check, though -
we are safe exactly when refcount is less than 2.

It was a long time ago; pre-2.6.12 for ioctl() (the codepath leading
to ppp one) and 2.6.17 for sendmsg() (netlink one).  OTOH,
netlink hadn't grown that check until 3.9 and ppp used to live
in drivers/net, not drivers/net/ppp until 3.1.  The bug existed
well before that, though, and the same fix used to apply in old
location of file.

Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Silences the following sparse warnings:
net/netlink/af_netlink.c:2926:21: warning: context imbalance in 'netlink_seq_start' - wrong count at exit
net/netlink/af_netlink.c:2972:13: warning: context imbalance in 'netlink_seq_stop' - unexpected unlock
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

netlink doesn't set any network header offset thus when the skb is
being passed to tap devices via dev_queue_xmit_nit(), it emits klog
false positives due to it being unset like:

  ...
  [  124.990397] protocol 0000 is buggy, dev nlmon0
  [  124.990411] protocol 0000 is buggy, dev nlmon0
  ...

So just reset the network header before passing to the device; for
packet sockets that just means nothing will change - mac and net
offset hold the same value just as before.
Reported-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Although RCU protection would be possible during diag dump, doing
so allows for concurrent table mutations which can render the
in-table offset between individual Netlink messages invalid and
thus cause legitimate sockets to be skipped in the dump.

Since the diag dump is relatively low volume and consistency is
more important than performance, the table mutex is held during
dump.
Reported-by: NAndrey Wagin <avagin@gmail.com>
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Fixes: e341694e ("netlink: Convert netlink_lookup() to use RCU protected hash table")
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With netlink_lookup() conversion to RCU, we need to use appropriate
rcu dereference in netlink_seq_socket_idx() & netlink_seq_next()
Reported-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Fixes: e341694e ("netlink: Convert netlink_lookup() to use RCU protected hash table")
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Heavy Netlink users such as Open vSwitch spend a considerable amount of
time in netlink_lookup() due to the read-lock on nl_table_lock. Use of
RCU relieves the lock contention.

Makes use of the new resizable hash table to avoid locking on the
lookup.

The hash table will grow if entries exceeds 75% of table size up to a
total table size of 64K. It will automatically shrink if usage falls
below 30%.

Also splits nl_table_lock into a separate mutex to protect hash table
mutations and allow synchronize_rcu() to sleep while waiting for readers
during expansion and shrinking.

Before:
   9.16%  kpktgend_0  [openvswitch]      [k] masked_flow_lookup
   6.42%  kpktgend_0  [pktgen]           [k] mod_cur_headers
   6.26%  kpktgend_0  [pktgen]           [k] pktgen_thread_worker
   6.23%  kpktgend_0  [kernel.kallsyms]  [k] memset
   4.79%  kpktgend_0  [kernel.kallsyms]  [k] netlink_lookup
   4.37%  kpktgend_0  [kernel.kallsyms]  [k] memcpy
   3.60%  kpktgend_0  [openvswitch]      [k] ovs_flow_extract
   2.69%  kpktgend_0  [kernel.kallsyms]  [k] jhash2

After:
  15.26%  kpktgend_0  [openvswitch]      [k] masked_flow_lookup
   8.12%  kpktgend_0  [pktgen]           [k] pktgen_thread_worker
   7.92%  kpktgend_0  [pktgen]           [k] mod_cur_headers
   5.11%  kpktgend_0  [kernel.kallsyms]  [k] memset
   4.11%  kpktgend_0  [openvswitch]      [k] ovs_flow_extract
   4.06%  kpktgend_0  [kernel.kallsyms]  [k] _raw_spin_lock
   3.90%  kpktgend_0  [kernel.kallsyms]  [k] jhash2
   [...]
   0.67%  kpktgend_0  [kernel.kallsyms]  [k] netlink_lookup
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Reviewed-by: NNikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use PAGE_ALIGNED(...) instead of IS_ALIGNED(..., PAGE_SIZE).
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch removes the bool variable 'pass'.
If the swith case exist return true or return false.
Signed-off-by: NVarka Bhadram <varkab@cdac.in>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

netlink_dump() returns a negative errno value on error.  Until now,
netlink_recvmsg() directly recorded that negative value in sk->sk_err, but
that's wrong since sk_err takes positive errno values.  (This manifests as
userspace receiving a positive return value from the recv() system call,
falsely indicating success.) This bug was introduced in the commit that
started checking the netlink_dump() return value, commit b44d211e (netlink:
handle errors from netlink_dump()).

Multithreaded Netlink dumps are one way to trigger this behavior in
practice, as described in the commit message for the userspace workaround
posted here:
    http://openvswitch.org/pipermail/dev/2014-June/042339.html

This commit also fixes the same bug in netlink_poll(), introduced in commit
cd1df525 (netlink: add flow control for memory mapped I/O).
Signed-off-by: NBen Pfaff <blp@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch changes the prototype of the do_one_broadcast() method so that it will return void.
Signed-off-by: NRami Rosen <ramirose@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It was possible to get a setuid root or setcap executable to write to
it's stdout or stderr (which has been set made a netlink socket) and
inadvertently reconfigure the networking stack.

To prevent this we check that both the creator of the socket and
the currentl applications has permission to reconfigure the network
stack.

Unfortunately this breaks Zebra which always uses sendto/sendmsg
and creates it's socket without any privileges.

To keep Zebra working don't bother checking if the creator of the
socket has privilege when a destination address is specified.  Instead
rely exclusively on the privileges of the sender of the socket.

Note from Andy: This is exactly Eric's code except for some comment
clarifications and formatting fixes.  Neither I nor, I think, anyone
else is thrilled with this approach, but I'm hesitant to wait on a
better fix since 3.15 is almost here.

Note to stable maintainers: This is a mess.  An earlier series of
patches in 3.15 fix a rather serious security issue (CVE-2014-0181),
but they did so in a way that breaks Zebra.  The offending series
includes:

    commit aa4cf945
    Author: Eric W. Biederman <ebiederm@xmission.com>
    Date:   Wed Apr 23 14:28:03 2014 -0700

        net: Add variants of capable for use on netlink messages

If a given kernel version is missing that series of fixes, it's
probably worth backporting it and this patch.  if that series is
present, then this fix is critical if you care about Zebra.

Cc: stable@vger.kernel.org
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

the local variable ops and n_ops were just read out from family,
and not changed, hence no need to assign back.

Validation functions should operate on const parameters and not
change anything.
Signed-off-by: NCheng Renquan <crquan@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It is possible by passing a netlink socket to a more privileged
executable and then to fool that executable into writing to the socket
data that happens to be valid netlink message to do something that
privileged executable did not intend to do.

To keep this from happening replace bare capable and ns_capable calls
with netlink_capable, netlink_net_calls and netlink_ns_capable calls.
Which act the same as the previous calls except they verify that the
opener of the socket had the desired permissions as well.
Reported-by: NAndy Lutomirski <luto@amacapital.net>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

netlink_net_capable - The common case use, for operations that are safe on a network namespace
netlink_capable - For operations that are only known to be safe for the global root
netlink_ns_capable - The general case of capable used to handle special cases

__netlink_ns_capable - Same as netlink_ns_capable except taking a netlink_skb_parms instead of
		       the skbuff of a netlink message.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>