linux-toradex.git/net/ipv4/tcp_minisocks.c, branch v4.9.33

tcp: do not inherit fastopen_req from parent

2017-05-14T12:00:21+00:00

[ Upstream commit 8b485ce69876c65db12ed390e7f9c0d2a64eff2c ]

Under fuzzer stress, it is possible that a child gets a non NULL
fastopen_req pointer from its parent at accept() time, when/if parent
morphs from listener to active session.

We need to make sure this can not happen, by clearing the field after
socket cloning.

BUG: Double free or freeing an invalid pointer
Unexpected shadow byte: 0xFB
CPU: 3 PID: 20933 Comm: syz-executor3 Not tainted 4.11.0+ #306
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
01/01/2011
Call Trace:
 
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x292/0x395 lib/dump_stack.c:52
 kasan_object_err+0x1c/0x70 mm/kasan/report.c:164
 kasan_report_double_free+0x5c/0x70 mm/kasan/report.c:185
 kasan_slab_free+0x9d/0xc0 mm/kasan/kasan.c:580
 slab_free_hook mm/slub.c:1357 [inline]
 slab_free_freelist_hook mm/slub.c:1379 [inline]
 slab_free mm/slub.c:2961 [inline]
 kfree+0xe8/0x2b0 mm/slub.c:3882
 tcp_free_fastopen_req net/ipv4/tcp.c:1077 [inline]
 tcp_disconnect+0xc15/0x13e0 net/ipv4/tcp.c:2328
 inet_child_forget+0xb8/0x600 net/ipv4/inet_connection_sock.c:898
 inet_csk_reqsk_queue_add+0x1e7/0x250
net/ipv4/inet_connection_sock.c:928
 tcp_get_cookie_sock+0x21a/0x510 net/ipv4/syncookies.c:217
 cookie_v4_check+0x1a19/0x28b0 net/ipv4/syncookies.c:384
 tcp_v4_cookie_check net/ipv4/tcp_ipv4.c:1384 [inline]
 tcp_v4_do_rcv+0x731/0x940 net/ipv4/tcp_ipv4.c:1421
 tcp_v4_rcv+0x2dc0/0x31c0 net/ipv4/tcp_ipv4.c:1715
 ip_local_deliver_finish+0x4cc/0xc20 net/ipv4/ip_input.c:216
 NF_HOOK include/linux/netfilter.h:257 [inline]
 ip_local_deliver+0x1ce/0x700 net/ipv4/ip_input.c:257
 dst_input include/net/dst.h:492 [inline]
 ip_rcv_finish+0xb1d/0x20b0 net/ipv4/ip_input.c:396
 NF_HOOK include/linux/netfilter.h:257 [inline]
 ip_rcv+0xd8c/0x19c0 net/ipv4/ip_input.c:487
 __netif_receive_skb_core+0x1ad1/0x3400 net/core/dev.c:4210
 __netif_receive_skb+0x2a/0x1a0 net/core/dev.c:4248
 process_backlog+0xe5/0x6c0 net/core/dev.c:4868
 napi_poll net/core/dev.c:5270 [inline]
 net_rx_action+0xe70/0x18e0 net/core/dev.c:5335
 __do_softirq+0x2fb/0xb99 kernel/softirq.c:284
 do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:899
 
 do_softirq.part.17+0x1e8/0x230 kernel/softirq.c:328
 do_softirq kernel/softirq.c:176 [inline]
 __local_bh_enable_ip+0x1cf/0x1e0 kernel/softirq.c:181
 local_bh_enable include/linux/bottom_half.h:31 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:931 [inline]
 ip_finish_output2+0x9ab/0x15e0 net/ipv4/ip_output.c:230
 ip_finish_output+0xa35/0xdf0 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:246 [inline]
 ip_output+0x1f6/0x7b0 net/ipv4/ip_output.c:404
 dst_output include/net/dst.h:486 [inline]
 ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124
 ip_queue_xmit+0x9a8/0x1a10 net/ipv4/ip_output.c:503
 tcp_transmit_skb+0x1ade/0x3470 net/ipv4/tcp_output.c:1057
 tcp_write_xmit+0x79e/0x55b0 net/ipv4/tcp_output.c:2265
 __tcp_push_pending_frames+0xfa/0x3a0 net/ipv4/tcp_output.c:2450
 tcp_push+0x4ee/0x780 net/ipv4/tcp.c:683
 tcp_sendmsg+0x128d/0x39b0 net/ipv4/tcp.c:1342
 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:633 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:643
 SYSC_sendto+0x660/0x810 net/socket.c:1696
 SyS_sendto+0x40/0x50 net/socket.c:1664
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x446059
RSP: 002b:00007faa6761fb58 EFLAGS: 00000282 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000017 RCX: 0000000000446059
RDX: 0000000000000001 RSI: 0000000020ba3fcd RDI: 0000000000000017
RBP: 00000000006e40a0 R08: 0000000020ba4ff0 R09: 0000000000000010
R10: 0000000020000000 R11: 0000000000000282 R12: 0000000000708150
R13: 0000000000000000 R14: 00007faa676209c0 R15: 00007faa67620700
Object at ffff88003b5bbcb8, in cache kmalloc-64 size: 64
Allocated:
PID = 20909
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:513
 set_track mm/kasan/kasan.c:525 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:616
 kmem_cache_alloc_trace+0x82/0x270 mm/slub.c:2745
 kmalloc include/linux/slab.h:490 [inline]
 kzalloc include/linux/slab.h:663 [inline]
 tcp_sendmsg_fastopen net/ipv4/tcp.c:1094 [inline]
 tcp_sendmsg+0x221a/0x39b0 net/ipv4/tcp.c:1139
 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:633 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:643
 SYSC_sendto+0x660/0x810 net/socket.c:1696
 SyS_sendto+0x40/0x50 net/socket.c:1664
 entry_SYSCALL_64_fastpath+0x1f/0xbe
Freed:
PID = 20909
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:513
 set_track mm/kasan/kasan.c:525 [inline]
 kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:589
 slab_free_hook mm/slub.c:1357 [inline]
 slab_free_freelist_hook mm/slub.c:1379 [inline]
 slab_free mm/slub.c:2961 [inline]
 kfree+0xe8/0x2b0 mm/slub.c:3882
 tcp_free_fastopen_req net/ipv4/tcp.c:1077 [inline]
 tcp_disconnect+0xc15/0x13e0 net/ipv4/tcp.c:2328
 __inet_stream_connect+0x20c/0xf90 net/ipv4/af_inet.c:593
 tcp_sendmsg_fastopen net/ipv4/tcp.c:1111 [inline]
 tcp_sendmsg+0x23a8/0x39b0 net/ipv4/tcp.c:1139
 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:633 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:643
 SYSC_sendto+0x660/0x810 net/socket.c:1696
 SyS_sendto+0x40/0x50 net/socket.c:1664
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
Fixes: 7db92362d2fe ("tcp: fix potential double free issue for fastopen_req")
Signed-off-by: Eric Dumazet 
Reported-by: Andrey Konovalov 
Acked-by: Wei Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: initialize icsk_ack.lrcvtime at session start time

2017-03-30T07:41:22+00:00

[ Upstream commit 15bb7745e94a665caf42bfaabf0ce062845b533b ]

icsk_ack.lrcvtime has a 0 value at socket creation time.

tcpi_last_data_recv can have bogus value if no payload is ever received.

This patch initializes icsk_ack.lrcvtime for active sessions
in tcp_finish_connect(), and for passive sessions in
tcp_create_openreq_child()

Signed-off-by: Eric Dumazet 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: track application-limited rate samples

2016-09-21T04:23:00+00:00

This commit adds code to track whether the delivery rate represented
by each rate_sample was limited by the application.

Upon each transmit, we store in the is_app_limited field in the skb a
boolean bit indicating whether there is a known "bubble in the pipe":
a point in the rate sample interval where the sender was
application-limited, and did not transmit even though the cwnd and
pacing rate allowed it.

This logic marks the flow app-limited on a write if *all* of the
following are true:

  1) There is less than 1 MSS of unsent data in the write queue
     available to transmit.

  2) There is no packet in the sender's queues (e.g. in fq or the NIC
     tx queue).

  3) The connection is not limited by cwnd.

  4) There are no lost packets to retransmit.

The tcp_rate_check_app_limited() code in tcp_rate.c determines whether
the connection is application-limited at the moment. If the flow is
application-limited, it sets the tp->app_limited field. If the flow is
application-limited then that means there is effectively a "bubble" of
silence in the pipe now, and this silence will be reflected in a lower
bandwidth sample for any rate samples from now until we get an ACK
indicating this bubble has exited the pipe: specifically, until we get
an ACK for the next packet we transmit.

When we send every skb we record in scb->tx.is_app_limited whether the
resulting rate sample will be application-limited.

The code in tcp_rate_gen() checks to see when it is safe to mark all
known application-limited bubbles of silence as having exited the
pipe. It does this by checking to see when the delivered count moves
past the tp->app_limited marker. At this point it zeroes the
tp->app_limited marker, as all known bubbles are out of the pipe.

We make room for the tx.is_app_limited bit in the skb by borrowing a
bit from the in_flight field used by NV to record the number of bytes
in flight. The receive window in the TCP header is 16 bits, and the
max receive window scaling shift factor is 14 (RFC 1323). So the max
receive window offered by the TCP protocol is 2^(16+14) = 2^30. So we
only need 30 bits for the tx.in_flight used by NV.

Signed-off-by: Van Jacobson 
Signed-off-by: Neal Cardwell 
Signed-off-by: Yuchung Cheng 
Signed-off-by: Nandita Dukkipati 
Signed-off-by: Eric Dumazet 
Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: David S. Miller

tcp: use windowed min filter library for TCP min_rtt estimation

2016-09-21T04:22:59+00:00

Refactor the TCP min_rtt code to reuse the new win_minmax library in
lib/win_minmax.c to simplify the TCP code.

This is a pure refactor: the functionality is exactly the same. We
just moved the windowed min code to make TCP easier to read and
maintain, and to allow other parts of the kernel to use the windowed
min/max filter code.

Signed-off-by: Van Jacobson 
Signed-off-by: Neal Cardwell 
Signed-off-by: Yuchung Cheng 
Signed-off-by: Nandita Dukkipati 
Signed-off-by: Eric Dumazet 
Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: David S. Miller

tcp: use an RB tree for ooo receive queue

2016-09-09T00:25:58+00:00

Over the years, TCP BDP has increased by several orders of magnitude,
and some people are considering to reach the 2 Gbytes limit.

Even with current window scale limit of 14, ~1 Gbytes maps to ~740,000
MSS.

In presence of packet losses (or reorders), TCP stores incoming packets
into an out of order queue, and number of skbs sitting there waiting for
the missing packets to be received can be in the 10^5 range.

Most packets are appended to the tail of this queue, and when
packets can finally be transferred to receive queue, we scan the queue
from its head.

However, in presence of heavy losses, we might have to find an arbitrary
point in this queue, involving a linear scan for every incoming packet,
throwing away cpu caches.

This patch converts it to a RB tree, to get bounded latencies.

Yaogong wrote a preliminary patch about 2 years ago.
Eric did the rebase, added ofo_last_skb cache, polishing and tests.

Tested with network dropping between 1 and 10 % packets, with good
success (about 30 % increase of throughput in stress tests)

Next step would be to also use an RB tree for the write queue at sender
side ;)

Signed-off-by: Yaogong Wang 
Signed-off-by: Eric Dumazet 
Cc: Yuchung Cheng 
Cc: Neal Cardwell 
Cc: Ilpo Järvinen 
Acked-By: Ilpo Järvinen 
Signed-off-by: David S. Miller

tcp: do not assume TCP code is non preemptible

2016-05-02T21:02:25+00:00

We want to to make TCP stack preemptible, as draining prequeue
and backlog queues can take lot of time.

Many SNMP updates were assuming that BH (and preemption) was disabled.

Need to convert some __NET_INC_STATS() calls to NET_INC_STATS()
and some __TCP_INC_STATS() to TCP_INC_STATS()

Before using this_cpu_ptr(net->ipv4.tcp_sk) in tcp_v4_send_reset()
and tcp_v4_send_ack(), we add an explicit preempt disabled section.

Signed-off-by: Eric Dumazet 
Acked-by: Soheil Hassas Yeganeh 
Signed-off-by: David S. Miller

net: rename NET_{ADD|INC}_STATS_BH()

2016-04-28T02:48:24+00:00

Rename NET_INC_STATS_BH() to __NET_INC_STATS()
and NET_ADD_STATS_BH() to __NET_ADD_STATS()

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: tcp: rename TCP_INC_STATS_BH

2016-04-28T02:48:23+00:00

Rename TCP_INC_STATS_BH() to __TCP_INC_STATS()

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: rate limit ACK sent by SYN_RECV request sockets

2016-04-05T02:11:20+00:00

Attackers like to use SYNFLOOD targeting one 5-tuple, as they
hit a single RX queue (and cpu) on the victim.

If they use random sequence numbers in their SYN, we detect
they do not match the expected window and send back an ACK.

This patch adds a rate limitation, so that the effect of such
attacks is limited to ingress only.

We roughly double our ability to absorb such attacks.

Signed-off-by: Eric Dumazet 
Cc: Willem de Bruijn 
Cc: Neal Cardwell 
Cc: Maciej Żenczykowski 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller

tcp: Add RFC4898 tcpEStatsPerfDataSegsOut/In

2016-03-14T18:55:26+00:00

Per RFC4898, they count segments sent/received
containing a positive length data segment (that includes
retransmission segments carrying data).  Unlike
tcpi_segs_out/in, tcpi_data_segs_out/in excludes segments
carrying no data (e.g. pure ack).

The patch also updates the segs_in in tcp_fastopen_add_skb()
so that segs_in >= data_segs_in property is kept.

Together with retransmission data, tcpi_data_segs_out
gives a better signal on the rxmit rate.

v6: Rebase on the latest net-next

v5: Eric pointed out that checking skb->len is still needed in
tcp_fastopen_add_skb() because skb can carry a FIN without data.
Hence, instead of open coding segs_in and data_segs_in, tcp_segs_in()
helper is used.  Comment is added to the fastopen case to explain why
segs_in has to be reset and tcp_segs_in() has to be called before
__skb_pull().

v4: Add comment to the changes in tcp_fastopen_add_skb()
and also add remark on this case in the commit message.

v3: Add const modifier to the skb parameter in tcp_segs_in()

v2: Rework based on recent fix by Eric:
commit a9d99ce28ed3 ("tcp: fix tcpi_segs_in after connection establishment")

Signed-off-by: Martin KaFai Lau 
Cc: Chris Rapier 
Cc: Eric Dumazet 
Cc: Marcelo Ricardo Leitner 
Cc: Neal Cardwell 
Cc: Yuchung Cheng 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller