linux.git/net/netfilter, branch v5.7-rc6 Linux kernel source tree netfilter: nft_set_rbtree: Add missing expired checks 2020-05-12T11:19:34+00:00 Phil Sutter phil@nwl.cc 2020-05-11T13:31:41+00:00 340eaff651160234bdbce07ef34b92a8e45cd540 Expired intervals would still match and be dumped to user space until garbage collection wiped them out. Make sure they stop matching and disappear (from users' perspective) as soon as they expire. Fixes: 8d8540c4f5e03 ("netfilter: nft_set_rbtree: add timeout support") Signed-off-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Expired intervals would still match and be dumped to user space until
garbage collection wiped them out. Make sure they stop matching and
disappear (from users' perspective) as soon as they expire.

Fixes: 8d8540c4f5e03 ("netfilter: nft_set_rbtree: add timeout support")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: flowtable: set NF_FLOW_TEARDOWN flag on entry expiration 2020-05-12T11:19:08+00:00 Pablo Neira Ayuso pablo@netfilter.org 2020-05-11T09:54:31+00:00 9ed81c8e0deb7bd2aa0d69371e4a0f9a7b31205d If the flow timer expires, the gc sets on the NF_FLOW_TEARDOWN flag. Otherwise, the flowtable software path might race to refresh the timeout, leaving the state machine in inconsistent state. Fixes: c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support") Reported-by: Paul Blakey <paulb@mellanox.com> Reviewed-by: Roi Dayan <roid@mellanox.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
If the flow timer expires, the gc sets on the NF_FLOW_TEARDOWN flag.
Otherwise, the flowtable software path might race to refresh the
timeout, leaving the state machine in inconsistent state.

Fixes: c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support")
Reported-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: conntrack: fix infinite loop on rmmod 2020-05-11T15:46:24+00:00 Florian Westphal fw@strlen.de 2020-05-10T12:28:07+00:00 54ab49fde95605a1077f759ce454d94e84b5ca45 'rmmod nf_conntrack' can hang forever, because the netns exit gets stuck in nf_conntrack_cleanup_net_list(): i_see_dead_people: busy = 0; list_for_each_entry(net, net_exit_list, exit_list) { nf_ct_iterate_cleanup(kill_all, net, 0, 0); if (atomic_read(&net->ct.count) != 0) busy = 1; } if (busy) { schedule(); goto i_see_dead_people; } When nf_ct_iterate_cleanup iterates the conntrack table, all nf_conn structures can be found twice: once for the original tuple and once for the conntracks reply tuple. get_next_corpse() only calls the iterator when the entry is in original direction -- the idea was to avoid unneeded invocations of the iterator callback. When support for clashing entries was added, the assumption that all nf_conn objects are added twice, once in original, once for reply tuple no longer holds -- NF_CLASH_BIT entries are only added in the non-clashing reply direction. Thus, if at least one NF_CLASH entry is in the list then nf_conntrack_cleanup_net_list() always skips it completely. During normal netns destruction, this causes a hang of several seconds, until the gc worker removes the entry (NF_CLASH entries always have a 1 second timeout). But in the rmmod case, the gc worker has already been stopped, so ct.count never becomes 0. We can fix this in two ways: 1. Add a second test for CLASH_BIT and call iterator for those entries as well, or: 2. Skip the original tuple direction and use the reply tuple. 2) is simpler, so do that. Fixes: 6a757c07e51f80ac ("netfilter: conntrack: allow insertion of clashing entries") Reported-by: Chen Yi <yiche@redhat.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
'rmmod nf_conntrack' can hang forever, because the netns exit
gets stuck in nf_conntrack_cleanup_net_list():

i_see_dead_people:
 busy = 0;
 list_for_each_entry(net, net_exit_list, exit_list) {
  nf_ct_iterate_cleanup(kill_all, net, 0, 0);
  if (atomic_read(&net->ct.count) != 0)
   busy = 1;
 }
 if (busy) {
  schedule();
  goto i_see_dead_people;
 }

When nf_ct_iterate_cleanup iterates the conntrack table, all nf_conn
structures can be found twice:
once for the original tuple and once for the conntracks reply tuple.

get_next_corpse() only calls the iterator when the entry is
in original direction -- the idea was to avoid unneeded invocations
of the iterator callback.

When support for clashing entries was added, the assumption that
all nf_conn objects are added twice, once in original, once for reply
tuple no longer holds -- NF_CLASH_BIT entries are only added in
the non-clashing reply direction.

Thus, if at least one NF_CLASH entry is in the list then
nf_conntrack_cleanup_net_list() always skips it completely.

During normal netns destruction, this causes a hang of several
seconds, until the gc worker removes the entry (NF_CLASH entries
always have a 1 second timeout).

But in the rmmod case, the gc worker has already been stopped, so
ct.count never becomes 0.

We can fix this in two ways:

1. Add a second test for CLASH_BIT and call iterator for those
   entries as well, or:
2. Skip the original tuple direction and use the reply tuple.

2) is simpler, so do that.

Fixes: 6a757c07e51f80ac ("netfilter: conntrack: allow insertion of clashing entries")
Reported-by: Chen Yi <yiche@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: flowtable: Remove WQ_MEM_RECLAIM from workqueue 2020-05-11T15:45:59+00:00 Roi Dayan roid@mellanox.com 2020-05-10T10:55:43+00:00 1d10da0eb09484ae087836da28258316ef4a02be This workqueue is in charge of handling offloaded flow tasks like add/del/stats we should not use WQ_MEM_RECLAIM flag. The flag can result in the following warning. [ 485.557189] ------------[ cut here ]------------ [ 485.562976] workqueue: WQ_MEM_RECLAIM nf_flow_table_offload:flow_offload_worr [ 485.562985] WARNING: CPU: 7 PID: 3731 at kernel/workqueue.c:2610 check_flush0 [ 485.590191] Kernel panic - not syncing: panic_on_warn set ... [ 485.597100] CPU: 7 PID: 3731 Comm: kworker/u112:8 Not tainted 5.7.0-rc1.21802 [ 485.606629] Hardware name: Dell Inc. PowerEdge R730/072T6D, BIOS 2.4.3 01/177 [ 485.615487] Workqueue: nf_flow_table_offload flow_offload_work_handler [nf_f] [ 485.624834] Call Trace: [ 485.628077] dump_stack+0x50/0x70 [ 485.632280] panic+0xfb/0x2d7 [ 485.636083] ? check_flush_dependency+0x110/0x130 [ 485.641830] __warn.cold.12+0x20/0x2a [ 485.646405] ? check_flush_dependency+0x110/0x130 [ 485.652154] ? check_flush_dependency+0x110/0x130 [ 485.657900] report_bug+0xb8/0x100 [ 485.662187] ? sched_clock_cpu+0xc/0xb0 [ 485.666974] do_error_trap+0x9f/0xc0 [ 485.671464] do_invalid_op+0x36/0x40 [ 485.675950] ? check_flush_dependency+0x110/0x130 [ 485.681699] invalid_op+0x28/0x30 Fixes: 7da182a998d6 ("netfilter: flowtable: Use work entry per offload command") Reported-by: Marcelo Ricardo Leitner <mleitner@redhat.com> Signed-off-by: Roi Dayan <roid@mellanox.com> Reviewed-by: Paul Blakey <paulb@mellanox.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
This workqueue is in charge of handling offloaded flow tasks like
add/del/stats we should not use WQ_MEM_RECLAIM flag.
The flag can result in the following warning.

[  485.557189] ------------[ cut here ]------------
[  485.562976] workqueue: WQ_MEM_RECLAIM nf_flow_table_offload:flow_offload_worr
[  485.562985] WARNING: CPU: 7 PID: 3731 at kernel/workqueue.c:2610 check_flush0
[  485.590191] Kernel panic - not syncing: panic_on_warn set ...
[  485.597100] CPU: 7 PID: 3731 Comm: kworker/u112:8 Not tainted 5.7.0-rc1.21802
[  485.606629] Hardware name: Dell Inc. PowerEdge R730/072T6D, BIOS 2.4.3 01/177
[  485.615487] Workqueue: nf_flow_table_offload flow_offload_work_handler [nf_f]
[  485.624834] Call Trace:
[  485.628077]  dump_stack+0x50/0x70
[  485.632280]  panic+0xfb/0x2d7
[  485.636083]  ? check_flush_dependency+0x110/0x130
[  485.641830]  __warn.cold.12+0x20/0x2a
[  485.646405]  ? check_flush_dependency+0x110/0x130
[  485.652154]  ? check_flush_dependency+0x110/0x130
[  485.657900]  report_bug+0xb8/0x100
[  485.662187]  ? sched_clock_cpu+0xc/0xb0
[  485.666974]  do_error_trap+0x9f/0xc0
[  485.671464]  do_invalid_op+0x36/0x40
[  485.675950]  ? check_flush_dependency+0x110/0x130
[  485.681699]  invalid_op+0x28/0x30

Fixes: 7da182a998d6 ("netfilter: flowtable: Use work entry per offload command")
Reported-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: flowtable: Add pending bit for offload work 2020-05-11T14:26:33+00:00 Paul Blakey paulb@mellanox.com 2020-05-06T11:24:39+00:00 2c8897953f3b2ff5498f3f275708a742bfcdbc24 Gc step can queue offloaded flow del work or stats work. Those work items can race each other and a flow could be freed before the stats work is executed and querying it. To avoid that, add a pending bit that if a work exists for a flow don't queue another work for it. This will also avoid adding multiple stats works in case stats work didn't complete but gc step started again. Signed-off-by: Paul Blakey <paulb@mellanox.com> Reviewed-by: Roi Dayan <roid@mellanox.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Gc step can queue offloaded flow del work or stats work.
Those work items can race each other and a flow could be freed
before the stats work is executed and querying it.
To avoid that, add a pending bit that if a work exists for a flow
don't queue another work for it.
This will also avoid adding multiple stats works in case stats work
didn't complete but gc step started again.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: conntrack: avoid gcc-10 zero-length-bounds warning 2020-05-10T21:20:24+00:00 Arnd Bergmann arnd@arndb.de 2020-04-30T21:30:48+00:00 2c407aca64977ede9b9f35158e919773cae2082f gcc-10 warns around a suspicious access to an empty struct member: net/netfilter/nf_conntrack_core.c: In function '__nf_conntrack_alloc': net/netfilter/nf_conntrack_core.c:1522:9: warning: array subscript 0 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[0]'} [-Wzero-length-bounds] 1522 | memset(&ct->__nfct_init_offset[0], 0, | ^~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from net/netfilter/nf_conntrack_core.c:37: include/net/netfilter/nf_conntrack.h:90:5: note: while referencing '__nfct_init_offset' 90 | u8 __nfct_init_offset[0]; | ^~~~~~~~~~~~~~~~~~ The code is correct but a bit unusual. Rework it slightly in a way that does not trigger the warning, using an empty struct instead of an empty array. There are probably more elegant ways to do this, but this is the smallest change. Fixes: c41884ce0562 ("netfilter: conntrack: avoid zeroing timer") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
gcc-10 warns around a suspicious access to an empty struct member:

net/netfilter/nf_conntrack_core.c: In function '__nf_conntrack_alloc':
net/netfilter/nf_conntrack_core.c:1522:9: warning: array subscript 0 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[0]'} [-Wzero-length-bounds]
 1522 |  memset(&ct->__nfct_init_offset[0], 0,
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from net/netfilter/nf_conntrack_core.c:37:
include/net/netfilter/nf_conntrack.h:90:5: note: while referencing '__nfct_init_offset'
   90 |  u8 __nfct_init_offset[0];
      |     ^~~~~~~~~~~~~~~~~~

The code is correct but a bit unusual. Rework it slightly in a way that
does not trigger the warning, using an empty struct instead of an empty
array. There are probably more elegant ways to do this, but this is the
smallest change.

Fixes: c41884ce0562 ("netfilter: conntrack: avoid zeroing timer")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: nf_osf: avoid passing pointer to local var 2020-04-29T19:17:57+00:00 Arnd Bergmann arnd@arndb.de 2020-04-29T19:00:41+00:00 c165d57b552aaca607fa5daf3fb524a6efe3c5a3 gcc-10 points out that a code path exists where a pointer to a stack variable may be passed back to the caller: net/netfilter/nfnetlink_osf.c: In function 'nf_osf_hdr_ctx_init': cc1: warning: function may return address of local variable [-Wreturn-local-addr] net/netfilter/nfnetlink_osf.c:171:16: note: declared here 171 | struct tcphdr _tcph; | ^~~~~ I am not sure whether this can happen in practice, but moving the variable declaration into the callers avoids the problem. Fixes: 31a9c29210e2 ("netfilter: nf_osf: add struct nf_osf_hdr_ctx") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
gcc-10 points out that a code path exists where a pointer to a stack
variable may be passed back to the caller:

net/netfilter/nfnetlink_osf.c: In function 'nf_osf_hdr_ctx_init':
cc1: warning: function may return address of local variable [-Wreturn-local-addr]
net/netfilter/nfnetlink_osf.c:171:16: note: declared here
  171 |  struct tcphdr _tcph;
      |                ^~~~~

I am not sure whether this can happen in practice, but moving the
variable declaration into the callers avoids the problem.

Fixes: 31a9c29210e2 ("netfilter: nf_osf: add struct nf_osf_hdr_ctx")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: nat: never update the UDP checksum when it's 0 2020-04-26T21:57:18+00:00 Guillaume Nault gnault@redhat.com 2020-04-21T00:42:19+00:00 ea64d8d6c675c0bb712689b13810301de9d8f77a If the UDP header of a local VXLAN endpoint is NAT-ed, and the VXLAN device has disabled UDP checksums and enabled Tx checksum offloading, then the skb passed to udp_manip_pkt() has hdr->check == 0 (outer checksum disabled) and skb->ip_summed == CHECKSUM_PARTIAL (inner packet checksum offloaded). Because of the ->ip_summed value, udp_manip_pkt() tries to update the outer checksum with the new address and port, leading to an invalid checksum sent on the wire, as the original null checksum obviously didn't take the old address and port into account. So, we can't take ->ip_summed into account in udp_manip_pkt(), as it might not refer to the checksum we're acting on. Instead, we can base the decision to update the UDP checksum entirely on the value of hdr->check, because it's null if and only if checksum is disabled: * A fully computed checksum can't be 0, since a 0 checksum is represented by the CSUM_MANGLED_0 value instead. * A partial checksum can't be 0, since the pseudo-header always adds at least one non-zero value (the UDP protocol type 0x11) and adding more values to the sum can't make it wrap to 0 as the carry is then added to the wrapped number. * A disabled checksum uses the special value 0. The problem seems to be there from day one, although it was probably not visible before UDP tunnels were implemented. Fixes: 5b1158e909ec ("[NETFILTER]: Add NAT support for nf_conntrack") Signed-off-by: Guillaume Nault <gnault@redhat.com> Reviewed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
If the UDP header of a local VXLAN endpoint is NAT-ed, and the VXLAN
device has disabled UDP checksums and enabled Tx checksum offloading,
then the skb passed to udp_manip_pkt() has hdr->check == 0 (outer
checksum disabled) and skb->ip_summed == CHECKSUM_PARTIAL (inner packet
checksum offloaded).

Because of the ->ip_summed value, udp_manip_pkt() tries to update the
outer checksum with the new address and port, leading to an invalid
checksum sent on the wire, as the original null checksum obviously
didn't take the old address and port into account.

So, we can't take ->ip_summed into account in udp_manip_pkt(), as it
might not refer to the checksum we're acting on. Instead, we can base
the decision to update the UDP checksum entirely on the value of
hdr->check, because it's null if and only if checksum is disabled:

  * A fully computed checksum can't be 0, since a 0 checksum is
    represented by the CSUM_MANGLED_0 value instead.

  * A partial checksum can't be 0, since the pseudo-header always adds
    at least one non-zero value (the UDP protocol type 0x11) and adding
    more values to the sum can't make it wrap to 0 as the carry is then
    added to the wrapped number.

  * A disabled checksum uses the special value 0.

The problem seems to be there from day one, although it was probably
not visible before UDP tunnels were implemented.

Fixes: 5b1158e909ec ("[NETFILTER]: Add NAT support for nf_conntrack")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2020-04-21T18:50:31+00:00 David S. Miller davem@davemloft.net 2020-04-21T18:50:31+00:00 76fc6a9a9a6a19213db86362ce0ff8299d7a6b9e Pablo Neira Ayuso says: ==================== Netfilter fixes for net The following patchset contains Netfilter fixes for net: 1) flow_block_cb memleak in nf_flow_table_offload_del_cb(), from Roi Dayan. 2) Fix error path handling in nf_nat_inet_register_fn(), from Hillf Danton. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> 
Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net:

1) flow_block_cb memleak in nf_flow_table_offload_del_cb(), from Roi Dayan.

2) Fix error path handling in nf_nat_inet_register_fn(), from Hillf Danton.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
netfilter: nat: fix error handling upon registering inet hook 2020-04-19T12:59:31+00:00 Hillf Danton hdanton@sina.com 2020-04-18T08:28:32+00:00 b4faef1739dd1f3b3981b8bf173a2266ea86b1eb A case of warning was reported by syzbot. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 19934 at net/netfilter/nf_nat_core.c:1106 nf_nat_unregister_fn+0x532/0x5c0 net/netfilter/nf_nat_core.c:1106 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 19934 Comm: syz-executor.5 Not tainted 5.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 panic+0x2e3/0x75c kernel/panic.c:221 __warn.cold+0x2f/0x35 kernel/panic.c:582 report_bug+0x27b/0x2f0 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:175 [inline] fixup_bug arch/x86/kernel/traps.c:170 [inline] do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 RIP: 0010:nf_nat_unregister_fn+0x532/0x5c0 net/netfilter/nf_nat_core.c:1106 Code: ff df 48 c1 ea 03 80 3c 02 00 75 75 48 8b 44 24 10 4c 89 ef 48 c7 00 00 00 00 00 e8 e8 f8 53 fb e9 4d fe ff ff e8 ee 9c 16 fb <0f> 0b e9 41 fe ff ff e8 e2 45 54 fb e9 b5 fd ff ff 48 8b 7c 24 20 RSP: 0018:ffffc90005487208 EFLAGS: 00010246 RAX: 0000000000040000 RBX: 0000000000000004 RCX: ffffc9001444a000 RDX: 0000000000040000 RSI: ffffffff865c94a2 RDI: 0000000000000005 RBP: ffff88808b5cf000 R08: ffff8880a2620140 R09: fffffbfff14bcd79 R10: ffffc90005487208 R11: fffffbfff14bcd78 R12: 0000000000000000 R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000000 nf_nat_ipv6_unregister_fn net/netfilter/nf_nat_proto.c:1017 [inline] nf_nat_inet_register_fn net/netfilter/nf_nat_proto.c:1038 [inline] nf_nat_inet_register_fn+0xfc/0x140 net/netfilter/nf_nat_proto.c:1023 nf_tables_register_hook net/netfilter/nf_tables_api.c:224 [inline] nf_tables_addchain.constprop.0+0x82e/0x13c0 net/netfilter/nf_tables_api.c:1981 nf_tables_newchain+0xf68/0x16a0 net/netfilter/nf_tables_api.c:2235 nfnetlink_rcv_batch+0x83a/0x1610 net/netfilter/nfnetlink.c:433 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:543 [inline] nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:561 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6bf/0x7e0 net/socket.c:2362 ___sys_sendmsg+0x100/0x170 net/socket.c:2416 __sys_sendmsg+0xec/0x1b0 net/socket.c:2449 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 and to quiesce it, unregister NFPROTO_IPV6 hook instead of NFPROTO_INET in case of failing to register NFPROTO_IPV4 hook. Reported-by: syzbot <syzbot+33e06702fd6cffc24c40@syzkaller.appspotmail.com> Fixes: d164385ec572 ("netfilter: nat: add inet family nat support") Cc: Florian Westphal <fw@strlen.de> Cc: Stefano Brivio <sbrivio@redhat.com> Signed-off-by: Hillf Danton <hdanton@sina.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
A case of warning was reported by syzbot.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 19934 at net/netfilter/nf_nat_core.c:1106
nf_nat_unregister_fn+0x532/0x5c0 net/netfilter/nf_nat_core.c:1106
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 19934 Comm: syz-executor.5 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 fixup_bug arch/x86/kernel/traps.c:170 [inline]
 do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:nf_nat_unregister_fn+0x532/0x5c0 net/netfilter/nf_nat_core.c:1106
Code: ff df 48 c1 ea 03 80 3c 02 00 75 75 48 8b 44 24 10 4c 89 ef 48 c7 00 00 00 00 00 e8 e8 f8 53 fb e9 4d fe ff ff e8 ee 9c 16 fb <0f> 0b e9 41 fe ff ff e8 e2 45 54 fb e9 b5 fd ff ff 48 8b 7c 24 20
RSP: 0018:ffffc90005487208 EFLAGS: 00010246
RAX: 0000000000040000 RBX: 0000000000000004 RCX: ffffc9001444a000
RDX: 0000000000040000 RSI: ffffffff865c94a2 RDI: 0000000000000005
RBP: ffff88808b5cf000 R08: ffff8880a2620140 R09: fffffbfff14bcd79
R10: ffffc90005487208 R11: fffffbfff14bcd78 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000000
 nf_nat_ipv6_unregister_fn net/netfilter/nf_nat_proto.c:1017 [inline]
 nf_nat_inet_register_fn net/netfilter/nf_nat_proto.c:1038 [inline]
 nf_nat_inet_register_fn+0xfc/0x140 net/netfilter/nf_nat_proto.c:1023
 nf_tables_register_hook net/netfilter/nf_tables_api.c:224 [inline]
 nf_tables_addchain.constprop.0+0x82e/0x13c0 net/netfilter/nf_tables_api.c:1981
 nf_tables_newchain+0xf68/0x16a0 net/netfilter/nf_tables_api.c:2235
 nfnetlink_rcv_batch+0x83a/0x1610 net/netfilter/nfnetlink.c:433
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:543 [inline]
 nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:561
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6bf/0x7e0 net/socket.c:2362
 ___sys_sendmsg+0x100/0x170 net/socket.c:2416
 __sys_sendmsg+0xec/0x1b0 net/socket.c:2449
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

and to quiesce it, unregister NFPROTO_IPV6 hook instead of NFPROTO_INET
in case of failing to register NFPROTO_IPV4 hook.

Reported-by: syzbot <syzbot+33e06702fd6cffc24c40@syzkaller.appspotmail.com>
Fixes: d164385ec572 ("netfilter: nat: add inet family nat support")
Cc: Florian Westphal <fw@strlen.de>
Cc: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>