linux.git/net/core, branch v4.12-rc5 Linux kernel source tree devlink: fix potential memort leak 2017-06-05T15:24:28+00:00 Haishuang Yan yanhaishuang@cmss.chinamobile.com 2017-06-05T00:57:21+00:00 6044bd4a7d580d4459b992bc6631c817486a1514 We must free allocated skb when genlmsg_put() return fails. Fixes: 1555d204e743 ("devlink: Support for pipeline debug (dpipe)") Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
We must free allocated skb when genlmsg_put() return fails.

Fixes: 1555d204e743 ("devlink: Support for pipeline debug (dpipe)")
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sock: reset sk_err when the error queue is empty 2017-06-05T00:01:53+00:00 Soheil Hassas Yeganeh soheil@google.com 2017-06-02T16:38:22+00:00 38b257938ac6655d0d6333743303231b9c465ec1 Prior to f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb), sk_err was reset to the error of the skb on the head of the error queue. Applications, most notably ping, are relying on this behavior to reset sk_err for ICMP packets. Set sk_err to the ICMP error when there is an ICMP packet at the head of the error queue. Fixes: f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb) Reported-by: Cyril Hrubis <chrubis@suse.cz> Tested-by: Cyril Hrubis <chrubis@suse.cz> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Prior to f5f99309fa74 (sock: do not set sk_err in
sock_dequeue_err_skb), sk_err was reset to the error of
the skb on the head of the error queue.

Applications, most notably ping, are relying on this
behavior to reset sk_err for ICMP packets.

Set sk_err to the ICMP error when there is an ICMP packet
at the head of the error queue.

Fixes: f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb)
Reported-by: Cyril Hrubis <chrubis@suse.cz>
Tested-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: add reference counting to metrics 2017-05-26T18:57:07+00:00 Eric Dumazet edumazet@google.com 2017-05-25T21:27:35+00:00 3fb07daff8e99243366a081e5129560734de4ada 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 82486aa6f1b9 ("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: 2860583fe840 ("ipv4: Kill rt->fi") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Julian Anastasov <ja@ssi.bg> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
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
82486aa6f1b9 ("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: 2860583fe840 ("ipv4: Kill rt->fi")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
bpf: add bpf_clone_redirect to bpf_helper_changes_pkt_data 2017-05-25T17:44:28+00:00 Daniel Borkmann daniel@iogearbox.net 2017-05-24T23:05:07+00:00 41703a731066fde79c3e5ccf3391cf77a98aeda5 The bpf_clone_redirect() still needs to be listed in bpf_helper_changes_pkt_data() since we call into bpf_try_make_head_writable() from there, thus we need to invalidate prior pkt regs as well. Fixes: 36bbef52c7eb ("bpf: direct packet write and access for helpers for clsact progs") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
The bpf_clone_redirect() still needs to be listed in
bpf_helper_changes_pkt_data() since we call into
bpf_try_make_head_writable() from there, thus we need
to invalidate prior pkt regs as well.

Fixes: 36bbef52c7eb ("bpf: direct packet write and access for helpers for clsact progs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: move somaxconn init from sysctl code 2017-05-25T17:12:17+00:00 Roman Kapl roman.kapl@sysgo.com 2017-05-24T08:22:22+00:00 7c3f1875c66fbc19762760097cabc91849ea0bbb The default value for somaxconn is set in sysctl_core_net_init(), but this function is not called when kernel is configured without CONFIG_SYSCTL. This results in the kernel not being able to accept TCP connections, because the backlog has zero size. Usually, the user ends up with: "TCP: request_sock_TCP: Possible SYN flooding on port 7. Dropping request. Check SNMP counters." If SYN cookies are not enabled the connection is rejected. Before ef547f2ac16 (tcp: remove max_qlen_log), the effects were less severe, because the backlog was always at least eight slots long. Signed-off-by: Roman Kapl <roman.kapl@sysgo.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The default value for somaxconn is set in sysctl_core_net_init(), but this
function is not called when kernel is configured without CONFIG_SYSCTL.

This results in the kernel not being able to accept TCP connections,
because the backlog has zero size. Usually, the user ends up with:
"TCP: request_sock_TCP: Possible SYN flooding on port 7. Dropping request.  Check SNMP counters."
If SYN cookies are not enabled the connection is rejected.

Before ef547f2ac16 (tcp: remove max_qlen_log), the effects were less
severe, because the backlog was always at least eight slots long.

Signed-off-by: Roman Kapl <roman.kapl@sysgo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: rtnetlink: bail out from rtnl_fdb_dump() on parse error 2017-05-24T19:27:16+00:00 Alexander Potapenko glider@google.com 2017-05-23T11:20:28+00:00 0ff50e83b5122e836ca492fefb11656b225ac29c 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: Alexander Potapenko <glider@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
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: Alexander Potapenko <glider@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: fix compile error in skb_orphan_partial() 2017-05-17T19:10:13+00:00 Eric Dumazet edumazet@google.com 2017-05-16T20:27:53+00:00 9142e9007f2d7ab58a587a1e1d921b0064a339aa If CONFIG_INET is not set, net/core/sock.c can not compile : net/core/sock.c: In function ‘skb_orphan_partial’: net/core/sock.c:1810:2: error: implicit declaration of function ‘skb_is_tcp_pure_ack’ [-Werror=implicit-function-declaration] if (skb_is_tcp_pure_ack(skb)) ^ Fix this by always including <net/tcp.h> Fixes: f6ba8d33cfbb ("netem: fix skb_orphan_partial()") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com> Reported-by: Randy Dunlap <rdunlap@infradead.org> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: David S. Miller <davem@davemloft.net> 
If CONFIG_INET is not set, net/core/sock.c can not compile :

net/core/sock.c: In function ‘skb_orphan_partial’:
net/core/sock.c:1810:2: error: implicit declaration of function
‘skb_is_tcp_pure_ack’ [-Werror=implicit-function-declaration]
  if (skb_is_tcp_pure_ack(skb))
  ^

Fix this by always including <net/tcp.h>

Fixes: f6ba8d33cfbb ("netem: fix skb_orphan_partial()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
neighbour: update neigh timestamps iff update is effective 2017-05-17T15:41:38+00:00 Ihar Hrachyshka ihrachys@redhat.com 2017-05-16T15:44:24+00:00 77d7123342dcf6442341b67816321d71da8b2b16 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: Ihar Hrachyshka <ihrachys@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
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: Ihar Hrachyshka <ihrachys@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: Improve handling of failures on link and route dumps 2017-05-16T18:54:11+00:00 David Ahern dsahern@gmail.com 2017-05-16T06:19:17+00:00 f6c5775ff0bfa62b072face6bf1d40f659f194b2 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: Jan Moskyto Matejka <mq@ucw.cz> Signed-off-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
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: Jan Moskyto Matejka <mq@ucw.cz>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
netem: fix skb_orphan_partial() 2017-05-12T01:32:48+00:00 Eric Dumazet edumazet@google.com 2017-05-11T22:24:41+00:00 f6ba8d33cfbb46df569972e64dbb5bb7e929bfd9 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: f2f872f9272a ("netem: Introduce skb_orphan_partial() helper") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Michael Madsen <mkm@nabto.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
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: f2f872f9272a ("netem: Introduce skb_orphan_partial() helper")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Michael Madsen <mkm@nabto.com>
Signed-off-by: David S. Miller <davem@davemloft.net>