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  1. 05 6月, 2017 4 次提交
    • J
      skbuff: return -EMSGSIZE in skb_to_sgvec to prevent overflow · 48a1df65
      由 Jason A. Donenfeld 提交于 
      This is a defense-in-depth measure in response to bugs like
4d6fa57b ("macsec: avoid heap overflow in skb_to_sgvec"). There's
not only a potential overflow of sglist items, but also a stack overflow
potential, so we fix this by limiting the amount of recursion this function
is allowed to do. Not actually providing a bounded base case is a future
disaster that we can easily avoid here.

As a small matter of house keeping, we take this opportunity to move the
documentation comment over the actual function the documentation is for.

While this could be implemented by using an explicit stack of skbuffs,
when implementing this, the function complexity increased considerably,
and I don't think such complexity and bloat is actually worth it. So,
instead I built this and tested it on x86, x86_64, ARM, ARM64, and MIPS,
and measured the stack usage there. I also reverted the recent MIPS
changes that give it a separate IRQ stack, so that I could experience
some worst-case situations. I found that limiting it to 24 layers deep
yielded a good stack usage with room for safety, as well as being much
deeper than any driver actually ever creates.
Signed-off-by: NJason A. Donenfeld <Jason@zx2c4.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: David Howells <dhowells@redhat.com>
Cc: Sabrina Dubroca <sd@queasysnail.net>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      48a1df65
    • S
      neigh: Really delete an arp/neigh entry on "ip neigh delete" or "arp -d" · 5071034e
      由 Sowmini Varadhan 提交于 
      The command
  # arp -s 62.2.0.1 a:b:c:d:e:f dev eth2
adds an entry like the following (listed by "arp -an")
  ? (62.2.0.1) at 0a:0b:0c:0d:0e:0f [ether] PERM on eth2
but the symmetric deletion command
  # arp -i eth2 -d 62.2.0.1
does not remove the PERM entry from the table, and instead leaves behind
  ? (62.2.0.1) at <incomplete> on eth2

The reason is that there is a refcnt of 1 for the arp_tbl itself
(neigh_alloc starts off the entry with a refcnt of 1), thus
the neigh_release() call from arp_invalidate() will (at best) just
decrement the ref to 1, but will never actually free it from the
table.

To fix this, we need to do something like neigh_forced_gc: if
the refcnt is 1 (i.e., on the table's ref), remove the entry from
the table and free it. This patch refactors and shares common code
between neigh_forced_gc and the newly added neigh_remove_one.

A similar issue exists for IPv6 Neighbor Cache entries, and is fixed
in a similar manner by this patch.
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Reviewed-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5071034e
    • J
      net-procfs: Use vsnprintf extension %phN · fbd0ac60
      由 Joe Perches 提交于 
      Save a bit of code by using the kernel extension.

$ size net/core/net-procfs.o*
   text	   data	    bss	    dec	    hex	filename
   3701	    120	      0	   3821	    eed	net/core/net-procfs.o.new
   3764	    120	      0	   3884	    f2c	net/core/net-procfs.o.old
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fbd0ac60
    • O
      net/flow_dissector: add support for dissection of misc ip header fields · 518d8a2e
      由 Or Gerlitz 提交于 
      Add support for dissection of ip tos and ttl and ipv6 traffic-class
and hoplimit. Both are dissected into the same struct.

Uses similar call to ip dissection function as with tcp, arp and others.
Signed-off-by: NOr Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      518d8a2e
  3. 01 6月, 2017 2 次提交
  5. 30 5月, 2017 2 次提交
  7. 28 5月, 2017 1 次提交
  9. 27 5月, 2017 1 次提交
    • E
      ipv4: add reference counting to metrics · 3fb07daf
      由 Eric Dumazet 提交于 
      Andrey Konovalov reported crashes in ipv4_mtu()

I could reproduce the issue with KASAN kernels, between
10.246.7.151 and 10.246.7.152 :

1) 20 concurrent netperf -t TCP_RR -H 10.246.7.152 -l 1000 &

2) At the same time run following loop :
while :
do
 ip ro add 10.246.7.152 dev eth0 src 10.246.7.151 mtu 1500
 ip ro del 10.246.7.152 dev eth0 src 10.246.7.151 mtu 1500
done

Cong Wang attempted to add back rt->fi in commit
82486aa6 ("ipv4: restore rt->fi for reference counting")
but this proved to add some issues that were complex to solve.

Instead, I suggested to add a refcount to the metrics themselves,
being a standalone object (in particular, no reference to other objects)

I tried to make this patch as small as possible to ease its backport,
instead of being super clean. Note that we believe that only ipv4 dst
need to take care of the metric refcount. But if this is wrong,
this patch adds the basic infrastructure to extend this to other
families.

Many thanks to Julian Anastasov for reviewing this patch, and Cong Wang
for his efforts on this problem.

Fixes: 2860583f ("ipv4: Kill rt->fi")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NJulian Anastasov <ja@ssi.bg>
Acked-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      3fb07daf
  11. 26 5月, 2017 2 次提交
  13. 25 5月, 2017 2 次提交
    • J
      net: flow_dissector: add support for dissection of tcp flags · ac4bb5de
      由 Jiri Pirko 提交于 
      Add support for dissection of tcp flags. Uses similar function call to
tcp dissection function as arp, mpls and others.
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Acked-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ac4bb5de
    • A
      net: rtnetlink: bail out from rtnl_fdb_dump() on parse error · 0ff50e83
      由 Alexander Potapenko 提交于 
      rtnl_fdb_dump() failed to check the result of nlmsg_parse(), which led
to contents of |ifm| being uninitialized because nlh->nlmsglen was too
small to accommodate |ifm|. The uninitialized data may affect some
branches and result in unwanted effects, although kernel data doesn't
seem to leak to the userspace directly.

The bug has been detected with KMSAN and syzkaller.

For the record, here is the KMSAN report:

==================================================================
BUG: KMSAN: use of unitialized memory in rtnl_fdb_dump+0x5dc/0x1000
CPU: 0 PID: 1039 Comm: probe Not tainted 4.11.0-rc5+ #2727
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16
 dump_stack+0x143/0x1b0 lib/dump_stack.c:52
 kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:1007
 __kmsan_warning_32+0x66/0xb0 mm/kmsan/kmsan_instr.c:491
 rtnl_fdb_dump+0x5dc/0x1000 net/core/rtnetlink.c:3230
 netlink_dump+0x84f/0x1190 net/netlink/af_netlink.c:2168
 __netlink_dump_start+0xc97/0xe50 net/netlink/af_netlink.c:2258
 netlink_dump_start ./include/linux/netlink.h:165
 rtnetlink_rcv_msg+0xae9/0xb40 net/core/rtnetlink.c:4094
 netlink_rcv_skb+0x339/0x5a0 net/netlink/af_netlink.c:2339
 rtnetlink_rcv+0x83/0xa0 net/core/rtnetlink.c:4110
 netlink_unicast_kernel net/netlink/af_netlink.c:1272
 netlink_unicast+0x13b7/0x1480 net/netlink/af_netlink.c:1298
 netlink_sendmsg+0x10b8/0x10f0 net/netlink/af_netlink.c:1844
 sock_sendmsg_nosec net/socket.c:633
 sock_sendmsg net/socket.c:643
 ___sys_sendmsg+0xd4b/0x10f0 net/socket.c:1997
 __sys_sendmsg net/socket.c:2031
 SYSC_sendmsg+0x2c6/0x3f0 net/socket.c:2042
 SyS_sendmsg+0x87/0xb0 net/socket.c:2038
 do_syscall_64+0x102/0x150 arch/x86/entry/common.c:285
 entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.S:246
RIP: 0033:0x401300
RSP: 002b:00007ffc3b0e6d58 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002b0 RCX: 0000000000401300
RDX: 0000000000000000 RSI: 00007ffc3b0e6d80 RDI: 0000000000000003
RBP: 00007ffc3b0e6e00 R08: 000000000000000b R09: 0000000000000004
R10: 000000000000000d R11: 0000000000000246 R12: 0000000000000000
R13: 00000000004065a0 R14: 0000000000406630 R15: 0000000000000000
origin: 000000008fe00056
 save_stack_trace+0x59/0x60 arch/x86/kernel/stacktrace.c:59
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:352
 kmsan_internal_poison_shadow+0xb1/0x1a0 mm/kmsan/kmsan.c:247
 kmsan_poison_shadow+0x6d/0xc0 mm/kmsan/kmsan.c:260
 slab_alloc_node mm/slub.c:2743
 __kmalloc_node_track_caller+0x1f4/0x390 mm/slub.c:4349
 __kmalloc_reserve net/core/skbuff.c:138
 __alloc_skb+0x2cd/0x740 net/core/skbuff.c:231
 alloc_skb ./include/linux/skbuff.h:933
 netlink_alloc_large_skb net/netlink/af_netlink.c:1144
 netlink_sendmsg+0x934/0x10f0 net/netlink/af_netlink.c:1819
 sock_sendmsg_nosec net/socket.c:633
 sock_sendmsg net/socket.c:643
 ___sys_sendmsg+0xd4b/0x10f0 net/socket.c:1997
 __sys_sendmsg net/socket.c:2031
 SYSC_sendmsg+0x2c6/0x3f0 net/socket.c:2042
 SyS_sendmsg+0x87/0xb0 net/socket.c:2038
 do_syscall_64+0x102/0x150 arch/x86/entry/common.c:285
 return_from_SYSCALL_64+0x0/0x6a arch/x86/entry/entry_64.S:246
==================================================================

and the reproducer:

==================================================================
  #include <sys/socket.h>
  #include <net/if_arp.h>
  #include <linux/netlink.h>
  #include <stdint.h>

  int main()
  {
    int sock = socket(PF_NETLINK, SOCK_DGRAM | SOCK_NONBLOCK, 0);
    struct msghdr msg;
    memset(&msg, 0, sizeof(msg));
    char nlmsg_buf[32];
    memset(nlmsg_buf, 0, sizeof(nlmsg_buf));
    struct nlmsghdr *nlmsg = nlmsg_buf;
    nlmsg->nlmsg_len = 0x11;
    nlmsg->nlmsg_type = 0x1e; // RTM_NEWROUTE = RTM_BASE + 0x0e
    // type = 0x0e = 1110b
    // kind = 2
    nlmsg->nlmsg_flags = 0x101; // NLM_F_ROOT | NLM_F_REQUEST
    nlmsg->nlmsg_seq = 0;
    nlmsg->nlmsg_pid = 0;
    nlmsg_buf[16] = (char)7;
    struct iovec iov;
    iov.iov_base = nlmsg_buf;
    iov.iov_len = 17;
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;
    sendmsg(sock, &msg, 0);
    return 0;
  }
==================================================================
Signed-off-by: NAlexander Potapenko <glider@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      0ff50e83
  15. 22 5月, 2017 4 次提交
  17. 20 5月, 2017 5 次提交
  19. 18 5月, 2017 4 次提交
  21. 17 5月, 2017 4 次提交
    • I
      neighbour: update neigh timestamps iff update is effective · 77d71233
      由 Ihar Hrachyshka 提交于 
      It's a common practice to send gratuitous ARPs after moving an
IP address to another device to speed up healing of a service. To
fulfill service availability constraints, the timing of network peers
updating their caches to point to a new location of an IP address can be
particularly important.

Sometimes neigh_update calls won't touch neither lladdr nor state, for
example if an update arrives in locktime interval. The neigh->updated
value is tested by the protocol specific neigh code, which in turn
will influence whether NEIGH_UPDATE_F_OVERRIDE gets set in the
call to neigh_update() or not. As a result, we may effectively ignore
the update request, bailing out of touching the neigh entry, except that
we still bump its timestamps inside neigh_update.

This may be a problem for updates arriving in quick succession. For
example, consider the following scenario:

A service is moved to another device with its IP address. The new device
sends three gratuitous ARP requests into the network with ~1 seconds
interval between them. Just before the first request arrives to one of
network peer nodes, its neigh entry for the IP address transitions from
STALE to DELAY.  This transition, among other things, updates
neigh->updated. Once the kernel receives the first gratuitous ARP, it
ignores it because its arrival time is inside the locktime interval. The
kernel still bumps neigh->updated. Then the second gratuitous ARP
request arrives, and it's also ignored because it's still in the (new)
locktime interval. Same happens for the third request. The node
eventually heals itself (after delay_first_probe_time seconds since the
initial transition to DELAY state), but it just wasted some time and
require a new ARP request/reply round trip. This unfortunate behaviour
both puts more load on the network, as well as reduces service
availability.

This patch changes neigh_update so that it bumps neigh->updated (as well
as neigh->confirmed) only once we are sure that either lladdr or entry
state will change). In the scenario described above, it means that the
second gratuitous ARP request will actually update the entry lladdr.

Ideally, we would update the neigh entry on the very first gratuitous
ARP request. The locktime mechanism is designed to ignore ARP updates in
a short timeframe after a previous ARP update was honoured by the kernel
layer. This would require tracking timestamps for state transitions
separately from timestamps when actual updates are received. This would
probably involve changes in neighbour struct. Therefore, the patch
doesn't tackle the issue of the first gratuitous APR ignored, leaving
it for a follow-up.
Signed-off-by: NIhar Hrachyshka <ihrachys@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      77d71233
    • E
      tcp: internal implementation for pacing · 218af599
      由 Eric Dumazet 提交于 
      BBR congestion control depends on pacing, and pacing is
currently handled by sch_fq packet scheduler for performance reasons,
and also because implemening pacing with FQ was convenient to truly
avoid bursts.

However there are many cases where this packet scheduler constraint
is not practical.
- Many linux hosts are not focusing on handling thousands of TCP
  flows in the most efficient way.
- Some routers use fq_codel or other AQM, but still would like
  to use BBR for the few TCP flows they initiate/terminate.

This patch implements an automatic fallback to internal pacing.

Pacing is requested either by BBR or use of SO_MAX_PACING_RATE option.

If sch_fq happens to be in the egress path, pacing is delegated to
the qdisc, otherwise pacing is done by TCP itself.

One advantage of pacing from TCP stack is to get more precise rtt
estimations, and less work done from TX completion, since TCP Small
queue limits are not generally hit. Setups with single TX queue but
many cpus might even benefit from this.

Note that unlike sch_fq, we do not take into account header sizes.
Taking care of these headers would add additional complexity for
no practical differences in behavior.

Some performance numbers using 800 TCP_STREAM flows rate limited to
~48 Mbit per second on 40Gbit NIC.

If MQ+pfifo_fast is used on the NIC :

$ sar -n DEV 1 5 | grep eth
14:48:44         eth0 725743.00 2932134.00  46776.76 4335184.68      0.00      0.00      1.00
14:48:45         eth0 725349.00 2932112.00  46751.86 4335158.90      0.00      0.00      0.00
14:48:46         eth0 725101.00 2931153.00  46735.07 4333748.63      0.00      0.00      0.00
14:48:47         eth0 725099.00 2931161.00  46735.11 4333760.44      0.00      0.00      1.00
14:48:48         eth0 725160.00 2931731.00  46738.88 4334606.07      0.00      0.00      0.00
Average:         eth0 725290.40 2931658.20  46747.54 4334491.74      0.00      0.00      0.40
$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 4  0      0 259825920  45644 2708324    0    0    21     2  247   98  0  0 100  0  0
 4  0      0 259823744  45644 2708356    0    0     0     0 2400825 159843  0 19 81  0  0
 0  0      0 259824208  45644 2708072    0    0     0     0 2407351 159929  0 19 81  0  0
 1  0      0 259824592  45644 2708128    0    0     0     0 2405183 160386  0 19 80  0  0
 1  0      0 259824272  45644 2707868    0    0     0    32 2396361 158037  0 19 81  0  0

Now use MQ+FQ :

lpaa23:~# echo fq >/proc/sys/net/core/default_qdisc
lpaa23:~# tc qdisc replace dev eth0 root mq

$ sar -n DEV 1 5 | grep eth
14:49:57         eth0 678614.00 2727930.00  43739.13 4033279.14      0.00      0.00      0.00
14:49:58         eth0 677620.00 2723971.00  43674.69 4027429.62      0.00      0.00      1.00
14:49:59         eth0 676396.00 2719050.00  43596.83 4020125.02      0.00      0.00      0.00
14:50:00         eth0 675197.00 2714173.00  43518.62 4012938.90      0.00      0.00      1.00
14:50:01         eth0 676388.00 2719063.00  43595.47 4020171.64      0.00      0.00      0.00
Average:         eth0 676843.00 2720837.40  43624.95 4022788.86      0.00      0.00      0.40
$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0      0 259832240  46008 2710912    0    0    21     2  223  192  0  1 99  0  0
 1  0      0 259832896  46008 2710744    0    0     0     0 1702206 198078  0 17 82  0  0
 0  0      0 259830272  46008 2710596    0    0     0     0 1696340 197756  1 17 83  0  0
 4  0      0 259829168  46024 2710584    0    0    16     0 1688472 197158  1 17 82  0  0
 3  0      0 259830224  46024 2710408    0    0     0     0 1692450 197212  0 18 82  0  0

As expected, number of interrupts per second is very different.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Van Jacobson <vanj@google.com>
Cc: Jerry Chu <hkchu@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      218af599
    • P
      net/sock: factor out dequeue/peek with offset code · 65101aec
      由 Paolo Abeni 提交于 
      And update __sk_queue_drop_skb() to work on the specified queue.
This will help the udp protocol to use an additional private
rx queue in a later patch.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      65101aec
    • D
      net: Improve handling of failures on link and route dumps · f6c5775f
      由 David Ahern 提交于 
      In general, rtnetlink dumps do not anticipate failure to dump a single
object (e.g., link or route) on a single pass. As both route and link
objects have grown via more attributes, that is no longer a given.

netlink dumps can handle a failure if the dump function returns an
error; specifically, netlink_dump adds the return code to the response
if it is <= 0 so userspace is notified of the failure. The missing
piece is the rtnetlink dump functions returning the error.

Fix route and link dump functions to return the errors if no object is
added to an skb (detected by skb->len != 0). IPv6 route dumps
(rt6_dump_route) already return the error; this patch updates IPv4 and
link dumps. Other dump functions may need to be ajusted as well.
Reported-by: NJan Moskyto Matejka <mq@ucw.cz>
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f6c5775f
  23. 12 5月, 2017 3 次提交
    • E
      netem: fix skb_orphan_partial() · f6ba8d33
      由 Eric Dumazet 提交于 
      I should have known that lowering skb->truesize was dangerous :/

In case packets are not leaving the host via a standard Ethernet device,
but looped back to local sockets, bad things can happen, as reported
by Michael Madsen ( https://bugzilla.kernel.org/show_bug.cgi?id=195713 )

So instead of tweaking skb->truesize, lets change skb->destructor
and keep a reference on the owner socket via its sk_refcnt.

Fixes: f2f872f9 ("netem: Introduce skb_orphan_partial() helper")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NMichael Madsen <mkm@nabto.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f6ba8d33
    • D
      xdp: refine xdp api with regards to generic xdp · d67b9cd2
      由 Daniel Borkmann 提交于 
      While working on the iproute2 generic XDP frontend, I noticed that
as of right now it's possible to have native *and* generic XDP
programs loaded both at the same time for the case when a driver
supports native XDP.

The intended model for generic XDP from b5cdae32 ("net: Generic
XDP") is, however, that only one out of the two can be present at
once which is also indicated as such in the XDP netlink dump part.
The main rationale for generic XDP is to ease accessibility (in
case a driver does not yet have XDP support) and to generically
provide a semantical model as an example for driver developers
wanting to add XDP support. The generic XDP option for an XDP
aware driver can still be useful for comparing and testing both
implementations.

However, it is not intended to have a second XDP processing stage
or layer with exactly the same functionality of the first native
stage. Only reason could be to have a partial fallback for future
XDP features that are not supported yet in the native implementation
and we probably also shouldn't strive for such fallback and instead
encourage native feature support in the first place. Given there's
currently no such fallback issue or use case, lets not go there yet
if we don't need to.

Therefore, change semantics for loading XDP and bail out if the
user tries to load a generic XDP program when a native one is
present and vice versa. Another alternative to bailing out would
be to handle the transition from one flavor to another gracefully,
but that would require to bring the device down, exchange both
types of programs, and bring it up again in order to avoid a tiny
window where a packet could hit both hooks. Given this complicates
the logic for just a debugging feature in the native case, I went
with the simpler variant.

For the dump, remove IFLA_XDP_FLAGS that was added with b5cdae32
and reuse IFLA_XDP_ATTACHED for indicating the mode. Dumping all
or just a subset of flags that were used for loading the XDP prog
is suboptimal in the long run since not all flags are useful for
dumping and if we start to reuse the same flag definitions for
load and dump, then we'll waste bit space. What we really just
want is to dump the mode for now.

Current IFLA_XDP_ATTACHED semantics are: nothing was installed (0),
a program is running at the native driver layer (1). Thus, add a
mode that says that a program is running at generic XDP layer (2).
Applications will handle this fine in that older binaries will
just indicate that something is attached at XDP layer, effectively
this is similar to IFLA_XDP_FLAGS attr that we would have had
modulo the redundancy.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d67b9cd2
    • D
      xdp: add flag to enforce driver mode · 0489df9a
      由 Daniel Borkmann 提交于 
      After commit b5cdae32 ("net: Generic XDP") we automatically fall
back to a generic XDP variant if the driver does not support native
XDP. Allow for an option where the user can specify that always the
native XDP variant should be selected and in case it's not supported
by a driver, just bail out.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      0489df9a
  25. 09 5月, 2017 2 次提交
  27. 06 5月, 2017 1 次提交
    • E
      tcp: randomize timestamps on syncookies · 84b114b9
      由 Eric Dumazet 提交于 
      Whole point of randomization was to hide server uptime, but an attacker
can simply start a syn flood and TCP generates 'old style' timestamps,
directly revealing server jiffies value.

Also, TSval sent by the server to a particular remote address vary
depending on syncookies being sent or not, potentially triggering PAWS
drops for innocent clients.

Lets implement proper randomization, including for SYNcookies.

Also we do not need to export sysctl_tcp_timestamps, since it is not
used from a module.

In v2, I added Florian feedback and contribution, adding tsoff to
tcp_get_cookie_sock().

v3 removed one unused variable in tcp_v4_connect() as Florian spotted.

Fixes: 95a22cae ("tcp: randomize tcp timestamp offsets for each connection")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NFlorian Westphal <fw@strlen.de>
Tested-by: NFlorian Westphal <fw@strlen.de>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      84b114b9
  29. 04 5月, 2017 1 次提交
  31. 02 5月, 2017 2 次提交