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  1. 27 9月, 2009 1 次提交
  3. 25 9月, 2009 1 次提交
    • J
      genetlink: fix netns vs. netlink table locking (2) · b8273570
      由 Johannes Berg 提交于 
      Similar to commit d136f1bd,
there's a bug when unregistering a generic netlink family,
which is caught by the might_sleep() added in that commit:

    BUG: sleeping function called from invalid context at net/netlink/af_netlink.c:183
    in_atomic(): 1, irqs_disabled(): 0, pid: 1510, name: rmmod
    2 locks held by rmmod/1510:
     #0:  (genl_mutex){+.+.+.}, at: [<ffffffff8138283b>] genl_unregister_family+0x2b/0x130
     #1:  (rcu_read_lock){.+.+..}, at: [<ffffffff8138270c>] __genl_unregister_mc_group+0x1c/0x120
    Pid: 1510, comm: rmmod Not tainted 2.6.31-wl #444
    Call Trace:
     [<ffffffff81044ff9>] __might_sleep+0x119/0x150
     [<ffffffff81380501>] netlink_table_grab+0x21/0x100
     [<ffffffff813813a3>] netlink_clear_multicast_users+0x23/0x60
     [<ffffffff81382761>] __genl_unregister_mc_group+0x71/0x120
     [<ffffffff81382866>] genl_unregister_family+0x56/0x130
     [<ffffffffa0007d85>] nl80211_exit+0x15/0x20 [cfg80211]
     [<ffffffffa000005a>] cfg80211_exit+0x1a/0x40 [cfg80211]

Fix in the same way by grabbing the netlink table lock
before doing rcu_read_lock().
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b8273570
  5. 22 9月, 2009 1 次提交
  7. 15 9月, 2009 1 次提交
    • J
      genetlink: fix netns vs. netlink table locking · d136f1bd
      由 Johannes Berg 提交于 
      Since my commits introducing netns awareness into
genetlink we can get this problem:

BUG: scheduling while atomic: modprobe/1178/0x00000002
2 locks held by modprobe/1178:
 #0:  (genl_mutex){+.+.+.}, at: [<ffffffff8135ee1a>] genl_register_mc_grou
 #1:  (rcu_read_lock){.+.+..}, at: [<ffffffff8135eeb5>] genl_register_mc_g
Pid: 1178, comm: modprobe Not tainted 2.6.31-rc8-wl-34789-g95cb731-dirty #
Call Trace:
 [<ffffffff8103e285>] __schedule_bug+0x85/0x90
 [<ffffffff81403138>] schedule+0x108/0x588
 [<ffffffff8135b131>] netlink_table_grab+0xa1/0xf0
 [<ffffffff8135c3a7>] netlink_change_ngroups+0x47/0x100
 [<ffffffff8135ef0f>] genl_register_mc_group+0x12f/0x290

because I overlooked that netlink_table_grab() will
schedule, thinking it was just the rwlock. However,
in the contention case, that isn't actually true.

Fix this by letting the code grab the netlink table
lock first and then the RCU for netns protection.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d136f1bd
  9. 25 8月, 2009 1 次提交
  11. 15 7月, 2009 1 次提交
    • J
      net/compat/wext: send different messages to compat tasks · 1dacc76d
      由 Johannes Berg 提交于 
      Wireless extensions have the unfortunate problem that events
are multicast netlink messages, and are not independent of
pointer size. Thus, currently 32-bit tasks on 64-bit platforms
cannot properly receive events and fail with all kinds of
strange problems, for instance wpa_supplicant never notices
disassociations, due to the way the 64-bit event looks (to a
32-bit process), the fact that the address is all zeroes is
lost, it thinks instead it is 00:00:00:00:01:00.

The same problem existed with the ioctls, until David Miller
fixed those some time ago in an heroic effort.

A different problem caused by this is that we cannot send the
ASSOCREQIE/ASSOCRESPIE events because sending them causes a
32-bit wpa_supplicant on a 64-bit system to overwrite its
internal information, which is worse than it not getting the
information at all -- so we currently resort to sending a
custom string event that it then parses. This, however, has a
severe size limitation we are frequently hitting with modern
access points; this limitation would can be lifted after this
patch by sending the correct binary, not custom, event.

A similar problem apparently happens for some other netlink
users on x86_64 with 32-bit tasks due to the alignment for
64-bit quantities.

In order to fix these problems, I have implemented a way to
send compat messages to tasks. When sending an event, we send
the non-compat event data together with a compat event data in
skb_shinfo(main_skb)->frag_list. Then, when the event is read
from the socket, the netlink code makes sure to pass out only
the skb that is compatible with the task. This approach was
suggested by David Miller, my original approach required
always sending two skbs but that had various small problems.

To determine whether compat is needed or not, I have used the
MSG_CMSG_COMPAT flag, and adjusted the call path for recv and
recvfrom to include it, even if those calls do not have a cmsg
parameter.

I have not solved one small part of the problem, and I don't
think it is necessary to: if a 32-bit application uses read()
rather than any form of recvmsg() it will still get the wrong
(64-bit) event. However, neither do applications actually do
this, nor would it be a regression.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1dacc76d
  13. 13 7月, 2009 2 次提交
  15. 18 6月, 2009 1 次提交
  17. 25 3月, 2009 1 次提交
    • P
      netlink: add NETLINK_NO_ENOBUFS socket flag · 38938bfe
      由 Pablo Neira Ayuso 提交于 
      This patch adds the NETLINK_NO_ENOBUFS socket flag. This flag can
be used by unicast and broadcast listeners to avoid receiving
ENOBUFS errors.

Generally speaking, ENOBUFS errors are useful to notify two things
to the listener:

a) You may increase the receiver buffer size via setsockopt().
b) You have lost messages, you may be out of sync.

In some cases, ignoring ENOBUFS errors can be useful. For example:

a) nfnetlink_queue: this subsystem does not have any sort of resync
method and you can decide to ignore ENOBUFS once you have set a
given buffer size.

b) ctnetlink: you can use this together with the socket flag
NETLINK_BROADCAST_SEND_ERROR to stop getting ENOBUFS errors as
you do not need to resync (packets whose event are not delivered
are drop to provide reliable logging and state-synchronization).

Moreover, the use of NETLINK_NO_ENOBUFS also reduces a "go up, go down"
effect in terms of performance which is due to the netlink congestion
control when the listener cannot back off. The effect is the following:

1) throughput rate goes up and netlink messages are inserted in the
receiver buffer.
2) Then, netlink buffer fills and overruns (set on nlk->state bit 0).
3) While the listener empties the receiver buffer, netlink keeps
dropping messages. Thus, throughput goes dramatically down.
4) Then, once the listener has emptied the buffer (nlk->state
bit 0 is set off), goto step 1.

This effect is easy to trigger with netlink broadcast under heavy
load, and it is more noticeable when using a big receiver buffer.
You can find some results in [1] that show this problem.

[1] http://1984.lsi.us.es/linux/netlink/

This patch also includes the use of sk_drop to account the number of
netlink messages drop due to overrun. This value is shown in
/proc/net/netlink.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      38938bfe
  19. 23 3月, 2009 1 次提交
  21. 04 3月, 2009 1 次提交
    • P
      netlink: invert error code in netlink_set_err() · 4843b93c
      由 Pablo Neira Ayuso 提交于 
      The callers of netlink_set_err() currently pass a negative value
as parameter for the error code. However, sk->sk_err wants a
positive error value. Without this patch, skb_recv_datagram() called
by netlink_recvmsg() may return a positive value to report an error.

Another choice to fix this is to change callers to pass a positive
error value, but this seems a bit inconsistent and error prone
to me. Indeed, the callers of netlink_set_err() assumed that the
(usual) negative value for error codes was fine before this patch :).

This patch also includes some documentation in docbook format
for netlink_set_err() to avoid this sort of confusion.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      4843b93c
  23. 27 2月, 2009 1 次提交
  25. 25 2月, 2009 1 次提交
    • P
      netlink: change nlmsg_notify() return value logic · 1ce85fe4
      由 Pablo Neira Ayuso 提交于 
      This patch changes the return value of nlmsg_notify() as follows:

If NETLINK_BROADCAST_ERROR is set by any of the listeners and
an error in the delivery happened, return the broadcast error;
else if there are no listeners apart from the socket that
requested a change with the echo flag, return the result of the
unicast notification. Thus, with this patch, the unicast
notification is handled in the same way of a broadcast listener
that has set the NETLINK_BROADCAST_ERROR socket flag.

This patch is useful in case that the caller of nlmsg_notify()
wants to know the result of the delivery of a netlink notification
(including the broadcast delivery) and take any action in case
that the delivery failed. For example, ctnetlink can drop packets
if the event delivery failed to provide reliable logging and
state-synchronization at the cost of dropping packets.

This patch also modifies the rtnetlink code to ignore the return
value of rtnl_notify() in all callers. The function rtnl_notify()
(before this patch) returned the error of the unicast notification
which makes rtnl_set_sk_err() reports errors to all listeners. This
is not of any help since the origin of the change (the socket that
requested the echoing) notices the ENOBUFS error if the notification
fails and should resync itself.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Acked-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1ce85fe4
  27. 20 2月, 2009 1 次提交
    • P
      netlink: add NETLINK_BROADCAST_ERROR socket option · be0c22a4
      由 Pablo Neira Ayuso 提交于 
      This patch adds NETLINK_BROADCAST_ERROR which is a netlink
socket option that the listener can set to make netlink_broadcast()
return errors in the delivery to the caller. This option is useful
if the caller of netlink_broadcast() do something with the result
of the message delivery, like in ctnetlink where it drops a network
packet if the event delivery failed, this is used to enable reliable
logging and state-synchronization. If this socket option is not set,
netlink_broadcast() only reports ESRCH errors and silently ignore
ENOBUFS errors, which is what most netlink_broadcast() callers
should do.

This socket option is based on a suggestion from Patrick McHardy.
Patrick McHardy can exchange this patch for a beer from me ;).
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Acked-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      be0c22a4
  29. 06 2月, 2009 1 次提交
    • P
      netlink: change return-value logic of netlink_broadcast() · ff491a73
      由 Pablo Neira Ayuso 提交于 
      Currently, netlink_broadcast() reports errors to the caller if no
messages at all were delivered:

1) If, at least, one message has been delivered correctly, returns 0.
2) Otherwise, if no messages at all were delivered due to skb_clone()
   failure, return -ENOBUFS.
3) Otherwise, if there are no listeners, return -ESRCH.

With this patch, the caller knows if the delivery of any of the
messages to the listeners have failed:

1) If it fails to deliver any message (for whatever reason), return
   -ENOBUFS.
2) Otherwise, if all messages were delivered OK, returns 0.
3) Otherwise, if no listeners, return -ESRCH.

In the current ctnetlink code and in Netfilter in general, we can add
reliable logging and connection tracking event delivery by dropping the
packets whose events were not successfully delivered over Netlink. Of
course, this option would be settable via /proc as this approach reduces
performance (in terms of filtered connections per seconds by a stateful
firewall) but providing reliable logging and event delivery (for
conntrackd) in return.

This patch also changes some clients of netlink_broadcast() that
may report ENOBUFS errors via printk. This error handling is not
of any help. Instead, the userspace daemons that are listening to
those netlink messages should resync themselves with the kernel-side
if they hit ENOBUFS.

BTW, netlink_broadcast() clients include those that call
cn_netlink_send(), nlmsg_multicast() and genlmsg_multicast() since they
internally call netlink_broadcast() and return its error value.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ff491a73
  31. 25 11月, 2008 1 次提交
  33. 24 11月, 2008 2 次提交
  35. 17 10月, 2008 1 次提交
  37. 14 10月, 2008 1 次提交
  39. 26 7月, 2008 1 次提交
  41. 02 7月, 2008 1 次提交
  43. 06 6月, 2008 1 次提交
  45. 28 4月, 2008 1 次提交
  47. 19 4月, 2008 1 次提交
  49. 26 3月, 2008 3 次提交
  51. 22 3月, 2008 1 次提交
  53. 01 3月, 2008 2 次提交
  55. 02 2月, 2008 1 次提交
  57. 01 2月, 2008 1 次提交
    • P
      [NETNS]: Fix race between put_net() and netlink_kernel_create(). · 23fe1866
      由 Pavel Emelyanov 提交于 
      The comment about "race free view of the set of network
namespaces" was a bit hasty. Look (there even can be only
one CPU, as discovered by Alexey Dobriyan and Denis Lunev):

put_net()
  if (atomic_dec_and_test(&net->refcnt))
    /* true */
      __put_net(net);
        queue_work(...);

/*
 * note: the net now has refcnt 0, but still in
 * the global list of net namespaces
 */

== re-schedule ==

register_pernet_subsys(&some_ops);
  register_pernet_operations(&some_ops);
    (*some_ops)->init(net);
      /*
       * we call netlink_kernel_create() here
       * in some places
       */
      netlink_kernel_create();
         sk_alloc();
            get_net(net); /* refcnt = 1 */
         /*
          * now we drop the net refcount not to
          * block the net namespace exit in the
          * future (or this can be done on the
          * error path)
          */
         put_net(sk->sk_net);
             if (atomic_dec_and_test(&...))
                   /*
                    * true. BOOOM! The net is
                    * scheduled for release twice
                    */

When thinking on this problem, I decided, that getting and
putting the net in init callback is wrong. If some init
callback needs to have a refcount-less reference on the struct
net, _it_ has to be careful himself, rather than relying on
the infrastructure to handle this correctly.

In case of netlink_kernel_create(), the problem is that the
sk_alloc() gets the given namespace, but passing the info
that we don't want to get it inside this call is too heavy.

Instead, I propose to crate the socket inside an init_net
namespace and then re-attach it to the desired one right
after the socket is created.

After doing this, we also have to be careful on error paths
not to drop the reference on the namespace, we didn't get
the one on.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Acked-by: NDenis Lunev <den@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      23fe1866
  59. 29 1月, 2008 6 次提交