syzbot found a use-after-free in inet6_mc_check [1]

The problem here is that inet6_mc_check() uses rcu
and read_lock(&iml->sflock)

So the fact that ip6_mc_leave_src() is called under RTNL
and the socket lock does not help us, we need to acquire
iml->sflock in write mode.

In the future, we should convert all this stuff to RCU.

[1]
BUG: KASAN: use-after-free in ipv6_addr_equal include/net/ipv6.h:521 [inline]
BUG: KASAN: use-after-free in inet6_mc_check+0xae7/0xb40 net/ipv6/mcast.c:649
Read of size 8 at addr ffff8801ce7f2510 by task syz-executor0/22432

CPU: 1 PID: 22432 Comm: syz-executor0 Not tainted 4.19.0-rc7+ #280
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+0x1c4/0x2b4 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 ipv6_addr_equal include/net/ipv6.h:521 [inline]
 inet6_mc_check+0xae7/0xb40 net/ipv6/mcast.c:649
 __raw_v6_lookup+0x320/0x3f0 net/ipv6/raw.c:98
 ipv6_raw_deliver net/ipv6/raw.c:183 [inline]
 raw6_local_deliver+0x3d3/0xcb0 net/ipv6/raw.c:240
 ip6_input_finish+0x467/0x1aa0 net/ipv6/ip6_input.c:345
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip6_input+0xe9/0x600 net/ipv6/ip6_input.c:426
 ip6_mc_input+0x48a/0xd20 net/ipv6/ip6_input.c:503
 dst_input include/net/dst.h:450 [inline]
 ip6_rcv_finish+0x17a/0x330 net/ipv6/ip6_input.c:76
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ipv6_rcv+0x120/0x640 net/ipv6/ip6_input.c:271
 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4913
 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5023
 netif_receive_skb_internal+0x12c/0x620 net/core/dev.c:5126
 napi_frags_finish net/core/dev.c:5664 [inline]
 napi_gro_frags+0x75a/0xc90 net/core/dev.c:5737
 tun_get_user+0x3189/0x4250 drivers/net/tun.c:1923
 tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:1968
 call_write_iter include/linux/fs.h:1808 [inline]
 do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680
 do_iter_write+0x185/0x5f0 fs/read_write.c:959
 vfs_writev+0x1f1/0x360 fs/read_write.c:1004
 do_writev+0x11a/0x310 fs/read_write.c:1039
 __do_sys_writev fs/read_write.c:1112 [inline]
 __se_sys_writev fs/read_write.c:1109 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457421
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 b5 fb ff c3 48 83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f2d30ecaba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000003e RCX: 0000000000457421
RDX: 0000000000000001 RSI: 00007f2d30ecabf0 RDI: 00000000000000f0
RBP: 0000000020000500 R08: 00000000000000f0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f2d30ecb6d4
R13: 00000000004c4890 R14: 00000000004d7b90 R15: 00000000ffffffff

Allocated by task 22437:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc mm/slab.c:3718 [inline]
 __kmalloc+0x14e/0x760 mm/slab.c:3727
 kmalloc include/linux/slab.h:518 [inline]
 sock_kmalloc+0x15a/0x1f0 net/core/sock.c:1983
 ip6_mc_source+0x14dd/0x1960 net/ipv6/mcast.c:427
 do_ipv6_setsockopt.isra.9+0x3afb/0x45d0 net/ipv6/ipv6_sockglue.c:743
 ipv6_setsockopt+0xbd/0x170 net/ipv6/ipv6_sockglue.c:933
 rawv6_setsockopt+0x59/0x140 net/ipv6/raw.c:1069
 sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3038
 __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
 __do_sys_setsockopt net/socket.c:1913 [inline]
 __se_sys_setsockopt net/socket.c:1910 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 22430:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xcf/0x230 mm/slab.c:3813
 __sock_kfree_s net/core/sock.c:2004 [inline]
 sock_kfree_s+0x29/0x60 net/core/sock.c:2010
 ip6_mc_leave_src+0x11a/0x1d0 net/ipv6/mcast.c:2448
 __ipv6_sock_mc_close+0x20b/0x4e0 net/ipv6/mcast.c:310
 ipv6_sock_mc_close+0x158/0x1d0 net/ipv6/mcast.c:328
 inet6_release+0x40/0x70 net/ipv6/af_inet6.c:452
 __sock_release+0xd7/0x250 net/socket.c:579
 sock_close+0x19/0x20 net/socket.c:1141
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801ce7f2500
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 16 bytes inside of
 192-byte region [ffff8801ce7f2500, ffff8801ce7f25c0)
The buggy address belongs to the page:
page:ffffea000739fc80 count:1 mapcount:0 mapping:ffff8801da800040 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0006f6e548 ffffea000737b948 ffff8801da800040
raw: 0000000000000000 ffff8801ce7f2000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ce7f2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801ce7f2480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8801ce7f2500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8801ce7f2580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801ce7f2600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When commit 27097255 ("[IPV6]: ROUTE: Add Router Reachability
Probing (RFC4191).") introduced router probing, the rt6_probe() function
required that a neighbour entry existed. This neighbour entry is used to
record the timestamp of the last probe via the ->updated field.

Later, commit 2152caea ("ipv6: Do not depend on rt->n in rt6_probe().")
removed the requirement for a neighbour entry. Neighbourless routes skip
the interval check and are not rate-limited.

This patch adds rate-limiting for neighbourless routes, by recording the
timestamp of the last probe in the fib6_info itself.

Fixes: 2152caea ("ipv6: Do not depend on rt->n in rt6_probe().")
Signed-off-by: NSabrina Dubroca <sd@queasysnail.net>
Reviewed-by: NStefano Brivio <sbrivio@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The fib6_info_alloc() function allocates percpu memory to hold per CPU
pointers to rt6_info, but this memory is never freed. Fix it.

Fixes: a64efe14 ("net/ipv6: introduce fib6_info struct and helpers")
Signed-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In rawv6_send_hdrinc(), in order to avoid an extra dst_hold(), we
directly assign the dst to skb and set passed in dst to NULL to avoid
double free.
However, in error case, we free skb and then do stats update with the
dst pointer passed in. This causes use-after-free on the dst.
Fix it by taking rcu read lock right before dst could get released to
make sure dst does not get freed until the stats update is done.
Note: we don't have this issue in ipv4 cause dst is not used for stats
update in v4.

Syzkaller reported following crash:
BUG: KASAN: use-after-free in rawv6_send_hdrinc net/ipv6/raw.c:692 [inline]
BUG: KASAN: use-after-free in rawv6_sendmsg+0x4421/0x4630 net/ipv6/raw.c:921
Read of size 8 at addr ffff8801d95ba730 by task syz-executor0/32088

CPU: 1 PID: 32088 Comm: syz-executor0 Not tainted 4.19.0-rc2+ #93
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+0x1c4/0x2b4 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 rawv6_send_hdrinc net/ipv6/raw.c:692 [inline]
 rawv6_sendmsg+0x4421/0x4630 net/ipv6/raw.c:921
 inet_sendmsg+0x1a1/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2114
 __sys_sendmsg+0x11d/0x280 net/socket.c:2152
 __do_sys_sendmsg net/socket.c:2161 [inline]
 __se_sys_sendmsg net/socket.c:2159 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2159
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457099
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f83756edc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f83756ee6d4 RCX: 0000000000457099
RDX: 0000000000000000 RSI: 0000000020003840 RDI: 0000000000000004
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d4b30 R14: 00000000004c90b1 R15: 0000000000000000

Allocated by task 32088:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3554
 dst_alloc+0xbb/0x1d0 net/core/dst.c:105
 ip6_dst_alloc+0x35/0xa0 net/ipv6/route.c:353
 ip6_rt_cache_alloc+0x247/0x7b0 net/ipv6/route.c:1186
 ip6_pol_route+0x8f8/0xd90 net/ipv6/route.c:1895
 ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2093
 fib6_rule_lookup+0x277/0x860 net/ipv6/fib6_rules.c:122
 ip6_route_output_flags+0x2c5/0x350 net/ipv6/route.c:2121
 ip6_route_output include/net/ip6_route.h:88 [inline]
 ip6_dst_lookup_tail+0xe27/0x1d60 net/ipv6/ip6_output.c:951
 ip6_dst_lookup_flow+0xc8/0x270 net/ipv6/ip6_output.c:1079
 rawv6_sendmsg+0x12d9/0x4630 net/ipv6/raw.c:905
 inet_sendmsg+0x1a1/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2114
 __sys_sendmsg+0x11d/0x280 net/socket.c:2152
 __do_sys_sendmsg net/socket.c:2161 [inline]
 __se_sys_sendmsg net/socket.c:2159 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2159
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5356:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x83/0x290 mm/slab.c:3756
 dst_destroy+0x267/0x3c0 net/core/dst.c:141
 dst_destroy_rcu+0x16/0x19 net/core/dst.c:154
 __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
 rcu_do_batch kernel/rcu/tree.c:2576 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
 rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
 __do_softirq+0x30b/0xad8 kernel/softirq.c:292

Fixes: 1789a640 ("raw: avoid two atomics in xmit")
Signed-off-by: NWei Wang <weiwan@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The change to move metrics from the dst to rt6_info moved the call
to ip6_convert_metrics from ip6_route_add to ip6_route_info_create. In
doing so it makes the call in ip6_route_info_append redundant and
actually leaks the metrics installed as part of the ip6_route_info_create.
Remove the now unnecessary call.

Fixes: d4ead6b3 ("net/ipv6: move metrics from dst to rt6_info")
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The backend handling for /proc/net/if_inet6 in addrconf.c doesn't properly
handle starting/stopping the iteration.  The problem is that at some point
during the iteration, an overflow is detected and the process is
subsequently stopped.  The item being shown via seq_printf() when the
overflow occurs is not actually shown, though.  When start() is
subsequently called to resume iterating, it returns the next item, and
thus the item that was being processed when the overflow occurred never
gets printed.

Alter the meaning of the private data member "offset".  Currently, when it
is not 0 (which only happens at the very beginning), "offset" represents
the next hlist item to be printed.  After this change, "offset" always
represents the current item.

This is also consistent with the private data member "bucket", which
represents the current bucket, and also the use of "pos" as defined in
seq_file.txt:
    The pos passed to start() will always be either zero, or the most
    recent pos used in the previous session.
Signed-off-by: NJeff Barnhill <0xeffeff@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

the ip6 tunnel xmit ndo assumes that the processed skb always
contains an ip[v6] header, but syzbot has found a way to send
frames that fall short of this assumption, leading to the following splat:

BUG: KMSAN: uninit-value in ip6ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1307
[inline]
BUG: KMSAN: uninit-value in ip6_tnl_start_xmit+0x7d2/0x1ef0
net/ipv6/ip6_tunnel.c:1390
CPU: 0 PID: 4504 Comm: syz-executor558 Not tainted 4.16.0+ #87
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x185/0x1d0 lib/dump_stack.c:53
  kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
  ip6ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1307 [inline]
  ip6_tnl_start_xmit+0x7d2/0x1ef0 net/ipv6/ip6_tunnel.c:1390
  __netdev_start_xmit include/linux/netdevice.h:4066 [inline]
  netdev_start_xmit include/linux/netdevice.h:4075 [inline]
  xmit_one net/core/dev.c:3026 [inline]
  dev_hard_start_xmit+0x5f1/0xc70 net/core/dev.c:3042
  __dev_queue_xmit+0x27ee/0x3520 net/core/dev.c:3557
  dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590
  packet_snd net/packet/af_packet.c:2944 [inline]
  packet_sendmsg+0x7c70/0x8a30 net/packet/af_packet.c:2969
  sock_sendmsg_nosec net/socket.c:630 [inline]
  sock_sendmsg net/socket.c:640 [inline]
  ___sys_sendmsg+0xec0/0x1310 net/socket.c:2046
  __sys_sendmmsg+0x42d/0x800 net/socket.c:2136
  SYSC_sendmmsg+0xc4/0x110 net/socket.c:2167
  SyS_sendmmsg+0x63/0x90 net/socket.c:2162
  do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x441819
RSP: 002b:00007ffe58ee8268 EFLAGS: 00000213 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000441819
RDX: 0000000000000002 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00000000006cd018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000213 R12: 0000000000402510
R13: 00000000004025a0 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
  kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188
  kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314
  kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321
  slab_post_alloc_hook mm/slab.h:445 [inline]
  slab_alloc_node mm/slub.c:2737 [inline]
  __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369
  __kmalloc_reserve net/core/skbuff.c:138 [inline]
  __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206
  alloc_skb include/linux/skbuff.h:984 [inline]
  alloc_skb_with_frags+0x1d4/0xb20 net/core/skbuff.c:5234
  sock_alloc_send_pskb+0xb56/0x1190 net/core/sock.c:2085
  packet_alloc_skb net/packet/af_packet.c:2803 [inline]
  packet_snd net/packet/af_packet.c:2894 [inline]
  packet_sendmsg+0x6454/0x8a30 net/packet/af_packet.c:2969
  sock_sendmsg_nosec net/socket.c:630 [inline]
  sock_sendmsg net/socket.c:640 [inline]
  ___sys_sendmsg+0xec0/0x1310 net/socket.c:2046
  __sys_sendmmsg+0x42d/0x800 net/socket.c:2136
  SYSC_sendmmsg+0xc4/0x110 net/socket.c:2167
  SyS_sendmmsg+0x63/0x90 net/socket.c:2162
  do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2

This change addresses the issue adding the needed check before
accessing the inner header.

The ipv4 side of the issue is apparently there since the ipv4 over ipv6
initial support, and the ipv6 side predates git history.

Fixes: c4d3efaf ("[IPV6] IP6TUNNEL: Add support to IPv4 over IPv6 tunnel.")
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+3fde91d4d394747d6db4@syzkaller.appspotmail.com
Tested-by: NAlexander Potapenko <glider@google.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When dst->_metrics and f6i->fib6_metrics share the same memory, both
take reference count on the dst_metrics structure. However, when dst is
destroyed, ip6_dst_destroy() only invokes dst_destroy_metrics_generic()
which does not take care of READONLY metrics and does not release refcnt.
This causes memory leak.
Similar to ipv4 logic, the fix is to properly release refcnt and free
the memory space pointed by dst->_metrics if refcnt becomes 0.

Fixes: 93531c67 ("net/ipv6: separate handling of FIB entries from dst based routes")
Reported-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NWei Wang <weiwan@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit e70a3aad.

This change causes use-after-free on dst->_metrics.
The crash trace looks like this:
[   97.763269] BUG: KASAN: use-after-free in ip6_mtu+0x116/0x140
[   97.769038] Read of size 4 at addr ffff881781d2cf84 by task svw_NetThreadEv/8801

[   97.777954] CPU: 76 PID: 8801 Comm: svw_NetThreadEv Not tainted 4.15.0-smp-DEV #11
[   97.777956] Hardware name: Default string Default string/Indus_QC_02, BIOS 5.46.4 03/29/2018
[   97.777957] Call Trace:
[   97.777971]  [<ffffffff895709db>] dump_stack+0x4d/0x72
[   97.777985]  [<ffffffff881651df>] print_address_description+0x6f/0x260
[   97.777997]  [<ffffffff88165747>] kasan_report+0x257/0x370
[   97.778001]  [<ffffffff894488e6>] ? ip6_mtu+0x116/0x140
[   97.778004]  [<ffffffff881658b9>] __asan_report_load4_noabort+0x19/0x20
[   97.778008]  [<ffffffff894488e6>] ip6_mtu+0x116/0x140
[   97.778013]  [<ffffffff892bb91e>] tcp_current_mss+0x12e/0x280
[   97.778016]  [<ffffffff892bb7f0>] ? tcp_mtu_to_mss+0x2d0/0x2d0
[   97.778022]  [<ffffffff887b45b8>] ? depot_save_stack+0x138/0x4a0
[   97.778037]  [<ffffffff87c38985>] ? __mmdrop+0x145/0x1f0
[   97.778040]  [<ffffffff881643b1>] ? save_stack+0xb1/0xd0
[   97.778046]  [<ffffffff89264c82>] tcp_send_mss+0x22/0x220
[   97.778059]  [<ffffffff89273a49>] tcp_sendmsg_locked+0x4f9/0x39f0
[   97.778062]  [<ffffffff881642b4>] ? kasan_check_write+0x14/0x20
[   97.778066]  [<ffffffff89273550>] ? tcp_sendpage+0x60/0x60
[   97.778070]  [<ffffffff881cb359>] ? rw_copy_check_uvector+0x69/0x280
[   97.778075]  [<ffffffff8873c65f>] ? import_iovec+0x9f/0x430
[   97.778078]  [<ffffffff88164be7>] ? kasan_slab_free+0x87/0xc0
[   97.778082]  [<ffffffff8873c5c0>] ? memzero_page+0x140/0x140
[   97.778085]  [<ffffffff881642b4>] ? kasan_check_write+0x14/0x20
[   97.778088]  [<ffffffff89276f6c>] tcp_sendmsg+0x2c/0x50
[   97.778092]  [<ffffffff89276f6c>] ? tcp_sendmsg+0x2c/0x50
[   97.778098]  [<ffffffff89352d43>] inet_sendmsg+0x103/0x480
[   97.778102]  [<ffffffff89352c40>] ? inet_gso_segment+0x15b0/0x15b0
[   97.778105]  [<ffffffff890294da>] sock_sendmsg+0xba/0xf0
[   97.778108]  [<ffffffff8902ab6a>] ___sys_sendmsg+0x6ca/0x8e0
[   97.778113]  [<ffffffff87dccac1>] ? hrtimer_try_to_cancel+0x71/0x3b0
[   97.778116]  [<ffffffff8902a4a0>] ? copy_msghdr_from_user+0x3d0/0x3d0
[   97.778119]  [<ffffffff881646d1>] ? memset+0x31/0x40
[   97.778123]  [<ffffffff87a0cff5>] ? schedule_hrtimeout_range_clock+0x165/0x380
[   97.778127]  [<ffffffff87a0ce90>] ? hrtimer_nanosleep_restart+0x250/0x250
[   97.778130]  [<ffffffff87dcc700>] ? __hrtimer_init+0x180/0x180
[   97.778133]  [<ffffffff87dd1f82>] ? ktime_get_ts64+0x172/0x200
[   97.778137]  [<ffffffff8822b8ec>] ? __fget_light+0x8c/0x2f0
[   97.778141]  [<ffffffff8902d5c6>] __sys_sendmsg+0xe6/0x190
[   97.778144]  [<ffffffff8902d5c6>] ? __sys_sendmsg+0xe6/0x190
[   97.778147]  [<ffffffff8902d4e0>] ? SyS_shutdown+0x20/0x20
[   97.778152]  [<ffffffff87cd4370>] ? wake_up_q+0xe0/0xe0
[   97.778155]  [<ffffffff8902d670>] ? __sys_sendmsg+0x190/0x190
[   97.778158]  [<ffffffff8902d683>] SyS_sendmsg+0x13/0x20
[   97.778162]  [<ffffffff87a1600c>] do_syscall_64+0x2ac/0x430
[   97.778166]  [<ffffffff87c17515>] ? do_page_fault+0x35/0x3d0
[   97.778171]  [<ffffffff8960131f>] ? page_fault+0x2f/0x50
[   97.778174]  [<ffffffff89600071>] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[   97.778177] RIP: 0033:0x7f83fa36000d
[   97.778178] RSP: 002b:00007f83ef9229e0 EFLAGS: 00000293 ORIG_RAX: 000000000000002e
[   97.778180] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f83fa36000d
[   97.778182] RDX: 0000000000004000 RSI: 00007f83ef922f00 RDI: 0000000000000036
[   97.778183] RBP: 00007f83ef923040 R08: 00007f83ef9231f8 R09: 00007f83ef923168
[   97.778184] R10: 0000000000000000 R11: 0000000000000293 R12: 00007f83f69c5b40
[   97.778185] R13: 000000000000001c R14: 0000000000000001 R15: 0000000000004000

[   97.779684] Allocated by task 5919:
[   97.783185]  save_stack+0x46/0xd0
[   97.783187]  kasan_kmalloc+0xad/0xe0
[   97.783189]  kmem_cache_alloc_trace+0xdf/0x580
[   97.783190]  ip6_convert_metrics.isra.79+0x7e/0x190
[   97.783192]  ip6_route_info_create+0x60a/0x2480
[   97.783193]  ip6_route_add+0x1d/0x80
[   97.783195]  inet6_rtm_newroute+0xdd/0xf0
[   97.783198]  rtnetlink_rcv_msg+0x641/0xb10
[   97.783200]  netlink_rcv_skb+0x27b/0x3e0
[   97.783202]  rtnetlink_rcv+0x15/0x20
[   97.783203]  netlink_unicast+0x4be/0x720
[   97.783204]  netlink_sendmsg+0x7bc/0xbf0
[   97.783205]  sock_sendmsg+0xba/0xf0
[   97.783207]  ___sys_sendmsg+0x6ca/0x8e0
[   97.783208]  __sys_sendmsg+0xe6/0x190
[   97.783209]  SyS_sendmsg+0x13/0x20
[   97.783211]  do_syscall_64+0x2ac/0x430
[   97.783213]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2

[   97.784709] Freed by task 0:
[   97.785056] knetbase: Error: /proc/sys/net/core/txcs_enable does not exist
[   97.794497]  save_stack+0x46/0xd0
[   97.794499]  kasan_slab_free+0x71/0xc0
[   97.794500]  kfree+0x7c/0xf0
[   97.794501]  fib6_info_destroy_rcu+0x24f/0x310
[   97.794504]  rcu_process_callbacks+0x38b/0x1730
[   97.794506]  __do_softirq+0x1c8/0x5d0
Reported-by: NJohn Sperbeck <jsperbeck@google.com>
Signed-off-by: NWei Wang <weiwan@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

DST_NOCOUNT in dst_entry::flags tracks whether the entry counts
toward route cache size (net->ipv6.sysctl.ip6_rt_max_size).

If the flag is NOT set, dst_ops::pcpuc_entries counter is incremented
in dist_init() and decremented in dst_destroy().

This flag is tied to allocation/deallocation of dst_entry and
should not be copied from another dst/route. Otherwise it can happen
that dst_ops::pcpuc_entries counter grows until no new routes can
be allocated because the counter reached ip6_rt_max_size due to
DST_NOCOUNT not set and thus no counter decrements on gc-ed routes.

Fixes: 3b6761d1 ("net/ipv6: Move dst flags to booleans in fib entries")
Cc: David Ahern <dsahern@gmail.com>
Acked-by: NWei Wang <weiwan@google.com>
Signed-off-by: NPeter Oskolkov <posk@google.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the unlikely case ip6_xmit() has to call skb_realloc_headroom(),
we need to call skb_set_owner_w() before consuming original skb,
otherwise we risk a use-after-free.

Bring IPv6 in line with what we do in IPv4 to fix this.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently the UDPv6 early demux rx code path lacks some mandatory
checks, already implemented into the normal RX code path - namely
the checksum conversion and no_check6_rx check.

Similar to the previous commit, we move the common processing to
an UDPv6 specific helper and call it from both edemux code path
and normal code path. In respect to the UDPv4, we need to add an
explicit check for non zero csum according to no_check6_rx value.
Reported-by: NJianlin Shi <jishi@redhat.com>
Suggested-by: NXin Long <lucien.xin@gmail.com>
Fixes: c9f2c1ae ("udp6: fix socket leak on early demux")
Fixes: 2abb7cdc ("udp: Add support for doing checksum unnecessary conversion")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When splitting a GSO segment that consists of encapsulated packets, the
skb->mac_len of the segments can end up being set wrong, causing packet
drops in particular when using act_mirred and ifb interfaces in
combination with a qdisc that splits GSO packets.

This happens because at the time skb_segment() is called, network_header
will point to the inner header, throwing off the calculation in
skb_reset_mac_len(). The network_header is subsequently adjust by the
outer IP gso_segment handlers, but they don't set the mac_len.

Fix this by adding skb_reset_mac_len() calls to both the IPv4 and IPv6
gso_segment handlers, after they modify the network_header.

Many thanks to Eric Dumazet for his help in identifying the cause of
the bug.
Acked-by: NDave Taht <dave.taht@gmail.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NToke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In inet6_rtm_getroute, since Commit 93531c67 ("net/ipv6: separate
handling of FIB entries from dst based routes"), it has used rt->from
to dump route info instead of rt.

However for some route like cache, some of its information like flags
or gateway is not the same as that of the 'from' one. It caused 'ip
route get' to dump the wrong route information.

In Jianlin's testing, the output information even lost the expiration
time for a pmtu route cache due to the wrong fib6_flags.

So change to use rt6_info members for dst addr, src addr, flags and
gateway when it tries to dump a route entry without fibmatch set.

v1->v2:
  - not use rt6i_prefsrc.
  - also fix the gw dump issue.

Fixes: 93531c67 ("net/ipv6: separate handling of FIB entries from dst based routes")
Reported-by: NJianlin Shi <jishi@redhat.com>
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A kernel crash occurrs when defragmented packet is fragmented
in ip_do_fragment().
In defragment routine, skb_orphan() is called and
skb->ip_defrag_offset is set. but skb->sk and
skb->ip_defrag_offset are same union member. so that
frag->sk is not NULL.
Hence crash occurrs in skb->sk check routine in ip_do_fragment() when
defragmented packet is fragmented.

test commands:
   %iptables -t nat -I POSTROUTING -j MASQUERADE
   %hping3 192.168.4.2 -s 1000 -p 2000 -d 60000

splat looks like:
[  261.069429] kernel BUG at net/ipv4/ip_output.c:636!
[  261.075753] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[  261.083854] CPU: 1 PID: 1349 Comm: hping3 Not tainted 4.19.0-rc2+ #3
[  261.100977] RIP: 0010:ip_do_fragment+0x1613/0x2600
[  261.106945] Code: e8 e2 38 e3 fe 4c 8b 44 24 18 48 8b 74 24 08 e9 92 f6 ff ff 80 3c 02 00 0f 85 da 07 00 00 48 8b b5 d0 00 00 00 e9 25 f6 ff ff <0f> 0b 0f 0b 44 8b 54 24 58 4c 8b 4c 24 18 4c 8b 5c 24 60 4c 8b 6c
[  261.127015] RSP: 0018:ffff8801031cf2c0 EFLAGS: 00010202
[  261.134156] RAX: 1ffff1002297537b RBX: ffffed0020639e6e RCX: 0000000000000004
[  261.142156] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880114ba9bd8
[  261.150157] RBP: ffff880114ba8a40 R08: ffffed0022975395 R09: ffffed0022975395
[  261.158157] R10: 0000000000000001 R11: ffffed0022975394 R12: ffff880114ba9ca4
[  261.166159] R13: 0000000000000010 R14: ffff880114ba9bc0 R15: dffffc0000000000
[  261.174169] FS:  00007fbae2199700(0000) GS:ffff88011b400000(0000) knlGS:0000000000000000
[  261.183012] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  261.189013] CR2: 00005579244fe000 CR3: 0000000119bf4000 CR4: 00000000001006e0
[  261.198158] Call Trace:
[  261.199018]  ? dst_output+0x180/0x180
[  261.205011]  ? save_trace+0x300/0x300
[  261.209018]  ? ip_copy_metadata+0xb00/0xb00
[  261.213034]  ? sched_clock_local+0xd4/0x140
[  261.218158]  ? kill_l4proto+0x120/0x120 [nf_conntrack]
[  261.223014]  ? rt_cpu_seq_stop+0x10/0x10
[  261.227014]  ? find_held_lock+0x39/0x1c0
[  261.233008]  ip_finish_output+0x51d/0xb50
[  261.237006]  ? ip_fragment.constprop.56+0x220/0x220
[  261.243011]  ? nf_ct_l4proto_register_one+0x5b0/0x5b0 [nf_conntrack]
[  261.250152]  ? rcu_is_watching+0x77/0x120
[  261.255010]  ? nf_nat_ipv4_out+0x1e/0x2b0 [nf_nat_ipv4]
[  261.261033]  ? nf_hook_slow+0xb1/0x160
[  261.265007]  ip_output+0x1c7/0x710
[  261.269005]  ? ip_mc_output+0x13f0/0x13f0
[  261.273002]  ? __local_bh_enable_ip+0xe9/0x1b0
[  261.278152]  ? ip_fragment.constprop.56+0x220/0x220
[  261.282996]  ? nf_hook_slow+0xb1/0x160
[  261.287007]  raw_sendmsg+0x21f9/0x4420
[  261.291008]  ? dst_output+0x180/0x180
[  261.297003]  ? sched_clock_cpu+0x126/0x170
[  261.301003]  ? find_held_lock+0x39/0x1c0
[  261.306155]  ? stop_critical_timings+0x420/0x420
[  261.311004]  ? check_flags.part.36+0x450/0x450
[  261.315005]  ? _raw_spin_unlock_irq+0x29/0x40
[  261.320995]  ? _raw_spin_unlock_irq+0x29/0x40
[  261.326142]  ? cyc2ns_read_end+0x10/0x10
[  261.330139]  ? raw_bind+0x280/0x280
[  261.334138]  ? sched_clock_cpu+0x126/0x170
[  261.338995]  ? check_flags.part.36+0x450/0x450
[  261.342991]  ? __lock_acquire+0x4500/0x4500
[  261.348994]  ? inet_sendmsg+0x11c/0x500
[  261.352989]  ? dst_output+0x180/0x180
[  261.357012]  inet_sendmsg+0x11c/0x500
[ ... ]

v2:
 - clear skb->sk at reassembly routine.(Eric Dumarzet)

Fixes: fa0f5273 ("ip: use rb trees for IP frag queue.")
Suggested-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A policy may have been set up with multiple transforms (e.g., ESP
and ipcomp). In this situation, the ingress IPsec processing
iterates in xfrm_input() and applies each transform in turn,
processing the nexthdr to find any additional xfrm that may apply.

This patch resets the transport header back to network header
only after the last transformation so that subsequent xfrms
can find the correct transport header.

Fixes: 7785bba2 ("esp: Add a software GRO codepath")
Suggested-by: NSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NSowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>

man ip-tunnel ttl section says:
0 is a special value meaning that packets inherit the TTL value.

IPv4 tunnel respect this in ip_tunnel_xmit(), but IPv6 tunnel has not
implement it yet. To make IPv6 behave consistently with IP tunnel,
add ipv6 tunnel inherit support.
Signed-off-by: NHangbin Liu <liuhangbin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After commit d6990976 ("vti6: fix PMTU caching
and reporting on xmit"), some too big skbs might be potentially passed down to
__xfrm6_output, causing it to fail to transmit but not free the skb, causing a
leak of skb, and consequentially a leak of dst references.

After running pmtu.sh, that shows as failure to unregister devices in a namespace:

[  311.397671] unregister_netdevice: waiting for veth_b to become free. Usage count = 1

The fix is to call kfree_skb in case of transmit failures.

Fixes: dd767856 ("xfrm6: Don't call icmpv6_send on local error")
Signed-off-by: NThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Reviewed-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>

Jan reported a regression after an update to 4.18.5. In this case ipv6
default route is setup by systemd-networkd based on data from an RA. The
RA contains an MTU of 1492 which is used when the route is first inserted
but then systemd-networkd pushes down updates to the default route
without the mtu set.

Prior to the change to fib6_info, metrics such as MTU were held in the
dst_entry and rt6i_pmtu in rt6_info contained an update to the mtu if
any. ip6_mtu would look at rt6i_pmtu first and use it if set. If not,
the value from the metrics is used if it is set and finally falling
back to the idev value.

After the fib6_info change metrics are contained in the fib6_info struct
and there is no equivalent to rt6i_pmtu. To maintain consistency with
the old behavior the new code should only reset the MTU in the metrics
if the route update has it set.

Fixes: d4ead6b3 ("net/ipv6: move metrics from dst to rt6_info")
Reported-by: NJan Janssen <medhefgo@web.de>
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 80f1a0f4 ("net/ipv6: Put lwtstate when destroying fib6_info")
partially fixed the kmemleak [1], lwtstate can be copied from fib6_info,
with ip6_rt_copy_init(), and it should be done only once there.

rt->dst.lwtstate is set by ip6_rt_init_dst(), at the start of the function
ip6_rt_copy_init(), so there is no need to get it again at the end.

With this patch, lwtstate also isn't copied from RTF_REJECT routes.

[1]:
unreferenced object 0xffff880b6aaa14e0 (size 64):
  comm "ip", pid 10577, jiffies 4295149341 (age 1273.903s)
  hex dump (first 32 bytes):
    01 00 04 00 04 00 00 00 10 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<0000000018664623>] lwtunnel_build_state+0x1bc/0x420
    [<00000000b73aa29a>] ip6_route_info_create+0x9f7/0x1fd0
    [<00000000ee2c5d1f>] ip6_route_add+0x14/0x70
    [<000000008537b55c>] inet6_rtm_newroute+0xd9/0xe0
    [<000000002acc50f5>] rtnetlink_rcv_msg+0x66f/0x8e0
    [<000000008d9cd381>] netlink_rcv_skb+0x268/0x3b0
    [<000000004c893c76>] netlink_unicast+0x417/0x5a0
    [<00000000f2ab1afb>] netlink_sendmsg+0x70b/0xc30
    [<00000000890ff0aa>] sock_sendmsg+0xb1/0xf0
    [<00000000a2e7b66f>] ___sys_sendmsg+0x659/0x950
    [<000000001e7426c8>] __sys_sendmsg+0xde/0x170
    [<00000000fe411443>] do_syscall_64+0x9f/0x4a0
    [<000000001be7b28b>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [<000000006d21f353>] 0xffffffffffffffff

Fixes: 6edb3c96 ("net/ipv6: Defer initialization of dst to data path")
Signed-off-by: NAlexey Kodanev <alexey.kodanev@oracle.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 6d0bfe22 ("net: ipv6: Add IPv6 support to the ping socket.")
contains an error in the cleanup path of inet6_init(): when
proto_register(&pingv6_prot, 1) fails, we try to unregister
&pingv6_prot. When rawv6_init() fails, we skip unregistering
&pingv6_prot.

Example of panic (triggered by faking a failure of
 proto_register(&pingv6_prot, 1)):

    general protection fault: 0000 [#1] PREEMPT SMP KASAN PTI
    [...]
    RIP: 0010:__list_del_entry_valid+0x79/0x160
    [...]
    Call Trace:
     proto_unregister+0xbb/0x550
     ? trace_preempt_on+0x6f0/0x6f0
     ? sock_no_shutdown+0x10/0x10
     inet6_init+0x153/0x1b8

Fixes: 6d0bfe22 ("net: ipv6: Add IPv6 support to the ping socket.")
Signed-off-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 15e66807 ("ipv6: reorder icmpv6_init() and ip6_mr_init()")
moved the cleanup label for ipmr_fail, but should have changed the
contents of the cleanup labels as well. Now we can end up cleaning up
icmpv6 even though it hasn't been initialized (jump to icmp_fail or
ipmr_fail).

Simply undo things in the reverse order of their initialization.

Example of panic (triggered by faking a failure of icmpv6_init):

    kasan: GPF could be caused by NULL-ptr deref or user memory access
    general protection fault: 0000 [#1] PREEMPT SMP KASAN PTI
    [...]
    RIP: 0010:__list_del_entry_valid+0x79/0x160
    [...]
    Call Trace:
     ? lock_release+0x8a0/0x8a0
     unregister_pernet_operations+0xd4/0x560
     ? ops_free_list+0x480/0x480
     ? down_write+0x91/0x130
     ? unregister_pernet_subsys+0x15/0x30
     ? down_read+0x1b0/0x1b0
     ? up_read+0x110/0x110
     ? kmem_cache_create_usercopy+0x1b4/0x240
     unregister_pernet_subsys+0x1d/0x30
     icmpv6_cleanup+0x1d/0x30
     inet6_init+0x1b5/0x23f

Fixes: 15e66807 ("ipv6: reorder icmpv6_init() and ip6_mr_init()")
Signed-off-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Before the commit d6990976 ("vti6: fix PMTU caching and reporting
on xmit") '!skb->ignore_df' check was always true because the function
skb_scrub_packet() was called before it, resetting ignore_df to zero.

In the commit, skb_scrub_packet() was moved below, and now this check
can be false for the packet, e.g. when sending it in the two fragments,
this prevents successful PMTU updates in such case. The next attempts
to send the packet lead to the same tx error. Moreover, vti6 initial
MTU value relies on PMTU adjustments.

This issue can be reproduced with the following LTP test script:
    udp_ipsec_vti.sh -6 -p ah -m tunnel -s 2000

Fixes: ccd740cb ("vti6: Add pmtu handling to vti6_xmit.")
Signed-off-by: NAlexey Kodanev <alexey.kodanev@oracle.com>
Acked-by: NSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After erspan_ver is introudced, if erspan_ver is not set in iproute, its
value will be left 0 by default. Since Commit 02f99df1 ("erspan: fix
invalid erspan version."), it has broken the traffic due to the version
check in erspan_xmit if users are not aware of 'erspan_ver' param, like
using an old version of iproute.

To fix this compatibility problem, it sets erspan_ver to 1 by default
when adding an erspan dev in erspan_setup. Note that we can't do it in
ipgre_netlink_parms, as this function is also used by ipgre_changelink.

Fixes: 02f99df1 ("erspan: fix invalid erspan version.")
Reported-by: NJianlin Shi <jishi@redhat.com>
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 6edb3c96 ("net/ipv6: Defer initialization of dst to data path")
forgot to handle anycast route and init anycast rt->dst.input to ip6_forward.
Fix it by setting anycast rt->dst.input back to ip6_input.

Fixes: 6edb3c96 ("net/ipv6: Defer initialization of dst to data path")
Signed-off-by: NHangbin Liu <liuhangbin@gmail.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

All the 3 callers of addrconf_add_mroute() assert RTNL
lock, they don't take any additional lock either, so
it is safe to convert it to GFP_KERNEL.

Same for sit_add_v4_addrs().

Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Prior to the introduction of fib6_info lwtstate was managed by the dst
code. With fib6_info releasing lwtstate needs to be done when the struct
is freed.

Fixes: 93531c67 ("net/ipv6: separate handling of FIB entries from dst based routes")
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If load ip6_vti module and create a network namespace when set
fb_tunnels_only_for_init_net to 1, then exit the namespace will
cause following crash:

[ 6601.677036] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 6601.679057] PGD 8000000425eca067 P4D 8000000425eca067 PUD 424292067 PMD 0
[ 6601.680483] Oops: 0000 [#1] SMP PTI
[ 6601.681223] CPU: 7 PID: 93 Comm: kworker/u16:1 Kdump: loaded Tainted: G            E     4.18.0+ #3
[ 6601.683153] Hardware name: Fedora Project OpenStack Nova, BIOS seabios-1.7.5-11.el7 04/01/2014
[ 6601.684919] Workqueue: netns cleanup_net
[ 6601.685742] RIP: 0010:vti6_exit_batch_net+0x87/0xd0 [ip6_vti]
[ 6601.686932] Code: 7b 08 48 89 e6 e8 b9 ea d3 dd 48 8b 1b 48 85 db 75 ec 48 83 c5 08 48 81 fd 00 01 00 00 75 d5 49 8b 84 24 08 01 00 00 48 89 e6 <48> 8b 78 08 e8 90 ea d3 dd 49 8b 45 28 49 39 c6 4c 8d 68 d8 75 a1
[ 6601.690735] RSP: 0018:ffffa897c2737de0 EFLAGS: 00010246
[ 6601.691846] RAX: 0000000000000000 RBX: 0000000000000000 RCX: dead000000000200
[ 6601.693324] RDX: 0000000000000015 RSI: ffffa897c2737de0 RDI: ffffffff9f2ea9e0
[ 6601.694824] RBP: 0000000000000100 R08: 0000000000000000 R09: 0000000000000000
[ 6601.696314] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8dc323c07e00
[ 6601.697812] R13: ffff8dc324a63100 R14: ffffa897c2737e30 R15: ffffa897c2737e30
[ 6601.699345] FS:  0000000000000000(0000) GS:ffff8dc33fdc0000(0000) knlGS:0000000000000000
[ 6601.701068] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6601.702282] CR2: 0000000000000008 CR3: 0000000424966002 CR4: 00000000001606e0
[ 6601.703791] Call Trace:
[ 6601.704329]  cleanup_net+0x1b4/0x2c0
[ 6601.705268]  process_one_work+0x16c/0x370
[ 6601.706145]  worker_thread+0x49/0x3e0
[ 6601.706942]  kthread+0xf8/0x130
[ 6601.707626]  ? rescuer_thread+0x340/0x340
[ 6601.708476]  ? kthread_bind+0x10/0x10
[ 6601.709266]  ret_from_fork+0x35/0x40

Reproduce:
modprobe ip6_vti
echo 1 > /proc/sys/net/core/fb_tunnels_only_for_init_net
unshare -n
exit

This because ip6n->tnls_wc[0] point to fallback device in default, but
in non-default namespace, ip6n->tnls_wc[0] will be NULL, so add the NULL
check comparatively.

Fixes: e2948e5a ("ip6_vti: fix creating fallback tunnel device for vti6")
Signed-off-by: NHaishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When set fb_tunnels_only_for_init_net to 1, don't create fallback tunnel
device for vti6 when a new namespace is created.

Tested:
[root@builder2 ~]# modprobe ip6_tunnel
[root@builder2 ~]# modprobe ip6_vti
[root@builder2 ~]# echo 1 > /proc/sys/net/core/fb_tunnels_only_for_init_net
[root@builder2 ~]# unshare -n
[root@builder2 ~]# ip link
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN mode DEFAULT group
default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
Signed-off-by: NHaishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Same as ip_vti, use iptunnel_xmit_stats to updates stats in tunnel xmit
code path.
Signed-off-by: NHaishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Roman reports that DHCPv6 client no longer sees replies from server
due to

ip6tables -t raw -A PREROUTING -m rpfilter --invert -j DROP

rule.  We need to set the F_IFACE flag for linklocal addresses, they
are scoped per-device.

Fixes: 47b7e7f8 ("netfilter: don't set F_IFACE on ipv6 fib lookups")
Reported-by: NRoman Mamedov <rm@romanrm.net>
Tested-by: NRoman Mamedov <rm@romanrm.net>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Preventing the kernel from responding to ICMP Echo Requests messages
can be useful in several ways. The sysctl parameter
'icmp_echo_ignore_all' can be used to prevent the kernel from
responding to IPv4 ICMP echo requests. For IPv6 pings, such
a sysctl kernel parameter did not exist.

Add the ability to prevent the kernel from responding to IPv6
ICMP echo requests through the use of the following sysctl
parameter : /proc/sys/net/ipv6/icmp/echo_ignore_all.
Update the documentation to reflect this change.
Signed-off-by: NVirgile Jarry <virgile@acceis.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch allows a BPF_PROG_TYPE_SK_REUSEPORT bpf prog to select a
SO_REUSEPORT sk from a BPF_MAP_TYPE_REUSEPORT_ARRAY introduced in
the earlier patch.  "bpf_run_sk_reuseport()" will return -ECONNREFUSED
when the BPF_PROG_TYPE_SK_REUSEPORT prog returns SK_DROP.
The callers, in inet[6]_hashtable.c and ipv[46]/udp.c, are modified to
handle this case and return NULL immediately instead of continuing the
sk search from its hashtable.

It re-uses the existing SO_ATTACH_REUSEPORT_EBPF setsockopt to attach
BPF_PROG_TYPE_SK_REUSEPORT.  The "sk_reuseport_attach_bpf()" will check
if the attaching bpf prog is in the new SK_REUSEPORT or the existing
SOCKET_FILTER type and then check different things accordingly.

One level of "__reuseport_attach_prog()" call is removed.  The
"sk_unhashed() && ..." and "sk->sk_reuseport_cb" tests are pushed
back to "reuseport_attach_prog()" in sock_reuseport.c.  sock_reuseport.c
seems to have more knowledge on those test requirements than filter.c.
In "reuseport_attach_prog()", after new_prog is attached to reuse->prog,
the old_prog (if any) is also directly freed instead of returning the
old_prog to the caller and asking the caller to free.

The sysctl_optmem_max check is moved back to the
"sk_reuseport_attach_filter()" and "sk_reuseport_attach_bpf()".
As of other bpf prog types, the new BPF_PROG_TYPE_SK_REUSEPORT is only
bounded by the usual "bpf_prog_charge_memlock()" during load time
instead of bounded by both bpf_prog_charge_memlock and sysctl_optmem_max.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

IPv6 GRO over GRE tap is not working while GRO is not set
over the native interface.

gro_list_prepare function updates the same_flow variable
of existing sessions to 1 if their mac headers match the one
of the incoming packet.
same_flow is used to filter out non-matching sessions and keep
potential ones for aggregation.

The number of bytes to compare should be the number of bytes
in the mac headers. In gro_list_prepare this number is set to
be skb->dev->hard_header_len. For GRE interfaces this hard_header_len
should be as it is set in the initialization process (when GRE is
created), it should not be overridden. But currently it is being overridden
by the value that is actually supposed to represent the needed_headroom.
Therefore, the number of bytes compared in order to decide whether the
the mac headers are the same is greater than the length of the headers.

As it's documented in netdevice.h, hard_header_len is the maximum
hardware header length, and needed_headroom is the extra headroom
the hardware may need.
hard_header_len is basically all the bytes received by the physical
till layer 3 header of the packet received by the interface.
For example, if the interface is a GRE tap then the needed_headroom
should be the total length of the following headers:
IP header of the physical, GRE header, mac header of GRE.
It is often used to calculate the MTU of the created interface.

This patch removes the override of the hard_header_len, and
assigns the calculated value to needed_headroom.
This way, the comparison in gro_list_prepare is really of
the mac headers, and if the packets have the same mac headers
the same_flow will be set to 1.

Performance testing: 45% higher bandwidth.
Measuring bandwidth of single-stream IPv4 TCP traffic over IPv6
GRE tap while GRO is not set on the native.
NIC: ConnectX-4LX
Before (GRO not working) : 7.2 Gbits/sec
After (GRO working): 10.5 Gbits/sec
Signed-off-by: NMaria Pasechnik <mariap@mellanox.com>
Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When using an ip6tnl device in collect_md mode, the xmit methods ignore
the ipv6.src field present in skb_tunnel_info's key, both for route
calculation purposes (flowi6 construction) and for assigning the
packet's final ipv6h->saddr.

This makes it impossible specifying a desired ipv6 local address in the
encapsulating header (for example, when using tc action tunnel_key).

This is also not aligned with behavior of ipip (ipv4) in collect_md
mode, where the key->u.ipv4.src gets used.

Fix, by assigning fl6.saddr with given key->u.ipv6.src.
In case ipv6.src is not specified, ip6_tnl_xmit uses existing saddr
selection code.

Fixes: 8d79266b ("ip6_tunnel: add collect_md mode to IPv6 tunnels")
Signed-off-by: NShmulik Ladkani <shmulik.ladkani@gmail.com>
Reviewed-by: NEyal Birger <eyal.birger@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

According to RFC791, 68 bytes is the minimum size of IPv4 datagram every
device must be able to forward without further fragmentation while 576
bytes is the minimum size of IPv4 datagram every device has to be able
to receive, so in ip6_tnl_xmit(), 68(IPV4_MIN_MTU) should be the right
value for the ipv4 min mtu check in ip6_tnl_xmit.

While at it, change to use max() instead of if statement.

Fixes: c9fefa08 ("ip6_tunnel: get the min mtu properly in ip6_tnl_xmit")
Reported-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

All the callers of ip6_rt_copy_init()/rt6_set_from() hold refcnt
of the "from" fib6_info, so there is no need to hold fib6_metrics
refcnt again, because fib6_metrics refcnt is only released when
fib6_info is gone, that is, they have the same life time, so the
whole fib6_metrics refcnt can be removed actually.

This fixes a kmemleak warning reported by Sabrina.

Fixes: 93531c67 ("net/ipv6: separate handling of FIB entries from dst based routes")
Reported-by: NSabrina Dubroca <sd@queasysnail.net>
Cc: Sabrina Dubroca <sd@queasysnail.net>
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

don't bother with pathological cases, they only waste cycles.
IPv6 requires a minimum MTU of 1280 so we should never see fragments
smaller than this (except last frag).

v3: don't use awkward "-offset + len"
v2: drop IPv4 part, which added same check w. IPV4_MIN_MTU (68).
    There were concerns that there could be even smaller frags
    generated by intermediate nodes, e.g. on radio networks.

Cc: Peter Oskolkov <posk@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Similar to TCP OOO RX queue, it makes sense to use rb trees to store
IP fragments, so that OOO fragments are inserted faster.

Tested:

- a follow-up patch contains a rather comprehensive ip defrag
  self-test (functional)
- ran neper `udp_stream -c -H <host> -F 100 -l 300 -T 20`:
    netstat --statistics
    Ip:
        282078937 total packets received
        0 forwarded
        0 incoming packets discarded
        946760 incoming packets delivered
        18743456 requests sent out
        101 fragments dropped after timeout
        282077129 reassemblies required
        944952 packets reassembled ok
        262734239 packet reassembles failed
   (The numbers/stats above are somewhat better re:
    reassemblies vs a kernel without this patchset. More
    comprehensive performance testing TBD).
Reported-by: NJann Horn <jannh@google.com>
Reported-by: NJuha-Matti Tilli <juha-matti.tilli@iki.fi>
Suggested-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NPeter Oskolkov <posk@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a ICMPV6_PKT_TOOBIG is received from a link local address the pmtu will
be updated on a route with an arbitrary interface index. Subsequent packets
sent back to the same link local address may therefore end up not
considering the updated pmtu.

Current behavior breaks TAHI v6LC4.1.4 Reduce PMTU On-link. Referring to RFC
1981: Section 3: "Note that Path MTU Discovery must be performed even in
cases where a node "thinks" a destination is attached to the same link as
itself. In a situation such as when a neighboring router acts as proxy [ND]
for some destination, the destination can to appear to be directly
connected but is in fact more than one hop away."

Using the interface index from the incoming ICMPV6_PKT_TOOBIG when updating
the pmtu.
Signed-off-by: NGeorg Kohmann <geokohma@cisco.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>