1. 29 Jan, 2016 2 commits
    • Neal Cardwell's avatar
      tcp: fix tcp_mark_head_lost to check skb len before fragmenting · d88270ee
      Neal Cardwell authored
      This commit fixes a corner case in tcp_mark_head_lost() which was
      causing the WARN_ON(len > skb->len) in tcp_fragment() to fire.
      
      tcp_mark_head_lost() was assuming that if a packet has
      tcp_skb_pcount(skb) of N, then it's safe to fragment off a prefix of
      M*mss bytes, for any M < N. But with the tricky way TCP pcounts are
      maintained, this is not always true.
      
      For example, suppose the sender sends 4 1-byte packets and have the
      last 3 packet sacked. It will merge the last 3 packets in the write
      queue into an skb with pcount = 3 and len = 3 bytes. If another
      recovery happens after a sack reneging event, tcp_mark_head_lost()
      may attempt to split the skb assuming it has more than 2*MSS bytes.
      
      This sounds very counterintuitive, but as the commit description for
      the related commit c0638c24 ("tcp: don't fragment SACKed skbs in
      tcp_mark_head_lost()") notes, this is because tcp_shifted_skb()
      coalesces adjacent regions of SACKed skbs, and when doing this it
      preserves the sum of their packet counts in order to reflect the
      real-world dynamics on the wire. The c0638c24 commit tried to
      avoid problems by not fragmenting SACKed skbs, since SACKed skbs are
      where the non-proportionality between pcount and skb->len/mss is known
      to be possible. However, that commit did not handle the case where
      during a reneging event one of these weird SACKed skbs becomes an
      un-SACKed skb, which tcp_mark_head_lost() can then try to fragment.
      
      The fix is to simply mark the entire skb lost when this happens.
      This makes the recovery slightly more aggressive in such corner
      cases before we detect reordering. But once we detect reordering
      this code path is by-passed because FACK is disabled.
      Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
      Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d88270ee
    • Joe Stringer's avatar
      inet: frag: Always orphan skbs inside ip_defrag() · 8282f274
      Joe Stringer authored
      Later parts of the stack (including fragmentation) expect that there is
      never a socket attached to frag in a frag_list, however this invariant
      was not enforced on all defrag paths. This could lead to the
      BUG_ON(skb->sk) during ip_do_fragment(), as per the call stack at the
      end of this commit message.
      
      While the call could be added to openvswitch to fix this particular
      error, the head and tail of the frags list are already orphaned
      indirectly inside ip_defrag(), so it seems like the remaining fragments
      should all be orphaned in all circumstances.
      
      kernel BUG at net/ipv4/ip_output.c:586!
      [...]
      Call Trace:
       <IRQ>
       [<ffffffffa0205270>] ? do_output.isra.29+0x1b0/0x1b0 [openvswitch]
       [<ffffffffa02167a7>] ovs_fragment+0xcc/0x214 [openvswitch]
       [<ffffffff81667830>] ? dst_discard_out+0x20/0x20
       [<ffffffff81667810>] ? dst_ifdown+0x80/0x80
       [<ffffffffa0212072>] ? find_bucket.isra.2+0x62/0x70 [openvswitch]
       [<ffffffff810e0ba5>] ? mod_timer_pending+0x65/0x210
       [<ffffffff810b732b>] ? __lock_acquire+0x3db/0x1b90
       [<ffffffffa03205a2>] ? nf_conntrack_in+0x252/0x500 [nf_conntrack]
       [<ffffffff810b63c4>] ? __lock_is_held+0x54/0x70
       [<ffffffffa02051a3>] do_output.isra.29+0xe3/0x1b0 [openvswitch]
       [<ffffffffa0206411>] do_execute_actions+0xe11/0x11f0 [openvswitch]
       [<ffffffff810b63c4>] ? __lock_is_held+0x54/0x70
       [<ffffffffa0206822>] ovs_execute_actions+0x32/0xd0 [openvswitch]
       [<ffffffffa020b505>] ovs_dp_process_packet+0x85/0x140 [openvswitch]
       [<ffffffff810b63c4>] ? __lock_is_held+0x54/0x70
       [<ffffffffa02068a2>] ovs_execute_actions+0xb2/0xd0 [openvswitch]
       [<ffffffffa020b505>] ovs_dp_process_packet+0x85/0x140 [openvswitch]
       [<ffffffffa0215019>] ? ovs_ct_get_labels+0x49/0x80 [openvswitch]
       [<ffffffffa0213a1d>] ovs_vport_receive+0x5d/0xa0 [openvswitch]
       [<ffffffff810b732b>] ? __lock_acquire+0x3db/0x1b90
       [<ffffffff810b732b>] ? __lock_acquire+0x3db/0x1b90
       [<ffffffff810b732b>] ? __lock_acquire+0x3db/0x1b90
       [<ffffffffa0214895>] ? internal_dev_xmit+0x5/0x140 [openvswitch]
       [<ffffffffa02148fc>] internal_dev_xmit+0x6c/0x140 [openvswitch]
       [<ffffffffa0214895>] ? internal_dev_xmit+0x5/0x140 [openvswitch]
       [<ffffffff81660299>] dev_hard_start_xmit+0x2b9/0x5e0
       [<ffffffff8165fc21>] ? netif_skb_features+0xd1/0x1f0
       [<ffffffff81660f20>] __dev_queue_xmit+0x800/0x930
       [<ffffffff81660770>] ? __dev_queue_xmit+0x50/0x930
       [<ffffffff810b53f1>] ? mark_held_locks+0x71/0x90
       [<ffffffff81669876>] ? neigh_resolve_output+0x106/0x220
       [<ffffffff81661060>] dev_queue_xmit+0x10/0x20
       [<ffffffff816698e8>] neigh_resolve_output+0x178/0x220
       [<ffffffff816a8e6f>] ? ip_finish_output2+0x1ff/0x590
       [<ffffffff816a8e6f>] ip_finish_output2+0x1ff/0x590
       [<ffffffff816a8cee>] ? ip_finish_output2+0x7e/0x590
       [<ffffffff816a9a31>] ip_do_fragment+0x831/0x8a0
       [<ffffffff816a8c70>] ? ip_copy_metadata+0x1b0/0x1b0
       [<ffffffff816a9ae3>] ip_fragment.constprop.49+0x43/0x80
       [<ffffffff816a9c9c>] ip_finish_output+0x17c/0x340
       [<ffffffff8169a6f4>] ? nf_hook_slow+0xe4/0x190
       [<ffffffff816ab4c0>] ip_output+0x70/0x110
       [<ffffffff816a9b20>] ? ip_fragment.constprop.49+0x80/0x80
       [<ffffffff816aa9f9>] ip_local_out+0x39/0x70
       [<ffffffff816abf89>] ip_send_skb+0x19/0x40
       [<ffffffff816abfe3>] ip_push_pending_frames+0x33/0x40
       [<ffffffff816df21a>] icmp_push_reply+0xea/0x120
       [<ffffffff816df93d>] icmp_reply.constprop.23+0x1ed/0x230
       [<ffffffff816df9ce>] icmp_echo.part.21+0x4e/0x50
       [<ffffffff810b63c4>] ? __lock_is_held+0x54/0x70
       [<ffffffff810d5f9e>] ? rcu_read_lock_held+0x5e/0x70
       [<ffffffff816dfa06>] icmp_echo+0x36/0x70
       [<ffffffff816e0d11>] icmp_rcv+0x271/0x450
       [<ffffffff816a4ca7>] ip_local_deliver_finish+0x127/0x3a0
       [<ffffffff816a4bc1>] ? ip_local_deliver_finish+0x41/0x3a0
       [<ffffffff816a5160>] ip_local_deliver+0x60/0xd0
       [<ffffffff816a4b80>] ? ip_rcv_finish+0x560/0x560
       [<ffffffff816a46fd>] ip_rcv_finish+0xdd/0x560
       [<ffffffff816a5453>] ip_rcv+0x283/0x3e0
       [<ffffffff810b6302>] ? match_held_lock+0x192/0x200
       [<ffffffff816a4620>] ? inet_del_offload+0x40/0x40
       [<ffffffff8165d062>] __netif_receive_skb_core+0x392/0xae0
       [<ffffffff8165e68e>] ? process_backlog+0x8e/0x230
       [<ffffffff810b53f1>] ? mark_held_locks+0x71/0x90
       [<ffffffff8165d7c8>] __netif_receive_skb+0x18/0x60
       [<ffffffff8165e678>] process_backlog+0x78/0x230
       [<ffffffff8165e6dd>] ? process_backlog+0xdd/0x230
       [<ffffffff8165e355>] net_rx_action+0x155/0x400
       [<ffffffff8106b48c>] __do_softirq+0xcc/0x420
       [<ffffffff816a8e87>] ? ip_finish_output2+0x217/0x590
       [<ffffffff8178e78c>] do_softirq_own_stack+0x1c/0x30
       <EOI>
       [<ffffffff8106b88e>] do_softirq+0x4e/0x60
       [<ffffffff8106b948>] __local_bh_enable_ip+0xa8/0xb0
       [<ffffffff816a8eb0>] ip_finish_output2+0x240/0x590
       [<ffffffff816a9a31>] ? ip_do_fragment+0x831/0x8a0
       [<ffffffff816a9a31>] ip_do_fragment+0x831/0x8a0
       [<ffffffff816a8c70>] ? ip_copy_metadata+0x1b0/0x1b0
       [<ffffffff816a9ae3>] ip_fragment.constprop.49+0x43/0x80
       [<ffffffff816a9c9c>] ip_finish_output+0x17c/0x340
       [<ffffffff8169a6f4>] ? nf_hook_slow+0xe4/0x190
       [<ffffffff816ab4c0>] ip_output+0x70/0x110
       [<ffffffff816a9b20>] ? ip_fragment.constprop.49+0x80/0x80
       [<ffffffff816aa9f9>] ip_local_out+0x39/0x70
       [<ffffffff816abf89>] ip_send_skb+0x19/0x40
       [<ffffffff816abfe3>] ip_push_pending_frames+0x33/0x40
       [<ffffffff816d55d3>] raw_sendmsg+0x7d3/0xc30
       [<ffffffff810b732b>] ? __lock_acquire+0x3db/0x1b90
       [<ffffffff816e7557>] ? inet_sendmsg+0xc7/0x1d0
       [<ffffffff810b63c4>] ? __lock_is_held+0x54/0x70
       [<ffffffff816e759a>] inet_sendmsg+0x10a/0x1d0
       [<ffffffff816e7495>] ? inet_sendmsg+0x5/0x1d0
       [<ffffffff8163e398>] sock_sendmsg+0x38/0x50
       [<ffffffff8163ec5f>] ___sys_sendmsg+0x25f/0x270
       [<ffffffff811aadad>] ? handle_mm_fault+0x8dd/0x1320
       [<ffffffff8178c147>] ? _raw_spin_unlock+0x27/0x40
       [<ffffffff810529b2>] ? __do_page_fault+0x1e2/0x460
       [<ffffffff81204886>] ? __fget_light+0x66/0x90
       [<ffffffff8163f8e2>] __sys_sendmsg+0x42/0x80
       [<ffffffff8163f932>] SyS_sendmsg+0x12/0x20
       [<ffffffff8178cb17>] entry_SYSCALL_64_fastpath+0x12/0x6f
      Code: 00 00 44 89 e0 e9 7c fb ff ff 4c 89 ff e8 e7 e7 ff ff 41 8b 9d 80 00 00 00 2b 5d d4 89 d8 c1 f8 03 0f b7 c0 e9 33 ff ff f
       66 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48
      RIP  [<ffffffff816a9a92>] ip_do_fragment+0x892/0x8a0
       RSP <ffff88006d603170>
      
      Fixes: 7f8a436e ("openvswitch: Add conntrack action")
      Signed-off-by: default avatarJoe Stringer <joe@ovn.org>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8282f274
  2. 28 Jan, 2016 16 commits
  3. 26 Jan, 2016 1 commit
  4. 25 Jan, 2016 17 commits
  5. 21 Jan, 2016 4 commits