Convert the various uses of fallthrough comments to fallthrough;

Done via script
Link: https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/

And by hand:

net/ipv6/ip6_fib.c has a fallthrough comment outside of an #ifdef block
that causes gcc to emit a warning if converted in-place.

So move the new fallthrough; inside the containing #ifdef/#endif too.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is a straight-forward conversion case for the new function, keeping
the flow of the existing code as intact as possible.
Signed-off-by: NJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

syzbot was once again able to crash a host by setting a very small mtu
on loopback device.

Let's make inetdev_valid_mtu() available in include/net/ip.h,
and use it in ip_setup_cork(), so that we protect both ip_append_page()
and __ip_append_data()

Also add a READ_ONCE() when the device mtu is read.

Pairs this lockless read with one WRITE_ONCE() in __dev_set_mtu(),
even if other code paths might write over this field.

Add a big comment in include/linux/netdevice.h about dev->mtu
needing READ_ONCE()/WRITE_ONCE() annotations.

Hopefully we will add the missing ones in followup patches.

[1]

refcount_t: saturated; leaking memory.
WARNING: CPU: 0 PID: 9464 at lib/refcount.c:22 refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 9464 Comm: syz-executor850 Not tainted 5.4.0-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+0x197/0x210 lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x3e kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Code: 06 31 ff 89 de e8 c8 f5 e6 fd 84 db 0f 85 6f ff ff ff e8 7b f4 e6 fd 48 c7 c7 e0 71 4f 88 c6 05 56 a6 a4 06 01 e8 c7 a8 b7 fd <0f> 0b e9 50 ff ff ff e8 5c f4 e6 fd 0f b6 1d 3d a6 a4 06 31 ff 89
RSP: 0018:ffff88809689f550 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e4336 RDI: ffffed1012d13e9c
RBP: ffff88809689f560 R08: ffff88809c50a3c0 R09: fffffbfff15d31b1
R10: fffffbfff15d31b0 R11: ffffffff8ae98d87 R12: 0000000000000001
R13: 0000000000040100 R14: ffff888099041104 R15: ffff888218d96e40
 refcount_add include/linux/refcount.h:193 [inline]
 skb_set_owner_w+0x2b6/0x410 net/core/sock.c:1999
 sock_wmalloc+0xf1/0x120 net/core/sock.c:2096
 ip_append_page+0x7ef/0x1190 net/ipv4/ip_output.c:1383
 udp_sendpage+0x1c7/0x480 net/ipv4/udp.c:1276
 inet_sendpage+0xdb/0x150 net/ipv4/af_inet.c:821
 kernel_sendpage+0x92/0xf0 net/socket.c:3794
 sock_sendpage+0x8b/0xc0 net/socket.c:936
 pipe_to_sendpage+0x2da/0x3c0 fs/splice.c:458
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x3ee/0x7c0 fs/splice.c:636
 splice_from_pipe+0x108/0x170 fs/splice.c:671
 generic_splice_sendpage+0x3c/0x50 fs/splice.c:842
 do_splice_from fs/splice.c:861 [inline]
 direct_splice_actor+0x123/0x190 fs/splice.c:1035
 splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:990
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1078
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441409
Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffb64c4f78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441409
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 0000000000073b8a R08: 0000000000000010 R09: 0000000000000010
R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000402180
R13: 0000000000402210 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Fixes: 1470ddf7 ("inet: Remove explicit write references to sk/inet in ip_append_data")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of generally passing NULL to NF_HOOK_COND() for input device,
pass skb->dev which contains input device for routed skbs.

Note that iptables (both legacy and nft) reject rules with input
interface match from being added to POSTROUTING chains, but nftables
allows this.

Cc: Eric Garver <eric@garver.life>
Signed-off-by: NPhil Sutter <phil@nwl.cc>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This patch removes the iph field from the state structure, which is not
properly initialized. Instead, add a new field to make the "do we want
to set DF" be the state bit and move the code to set the DF flag from
ip_frag_next().

Joint work with Pablo and Linus.

Fixes: 19c3401a ("net: ipv4: place control buffer handling away from fragmentation iterators")
Reported-by: NPatrick Schönthaler <patrick@notvads.ovh>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Thomas found that some forwarded packets would be stuck
in FQ packet scheduler because their skb->tstamp contained
timestamps far in the future.

We thought we addressed this point in commit 8203e2d8
("net: clear skb->tstamp in forwarding paths") but there
is still an issue when/if a packet needs to be fragmented.

In order to meet EDT requirements, we have to make sure all
fragments get the original skb->tstamp.

Note that this original skb->tstamp should be zero in
forwarding path, but might have a non zero value in
output path if user decided so.

Fixes: fb420d5d ("tcp/fq: move back to CLOCK_MONOTONIC")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NThomas Bartschies <Thomas.Bartschies@cvk.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ctl packets sent on behalf of TIME_WAIT sockets currently
have a zero skb->priority, which can cause various problems.

In this patch we :

- add a tw_priority field in struct inet_timewait_sock.

- populate it from sk->sk_priority when a TIME_WAIT is created.

- For IPv4, change ip_send_unicast_reply() and its two
  callers to propagate tw_priority correctly.
  ip_send_unicast_reply() no longer changes sk->sk_priority.

- For IPv6, make sure TIME_WAIT sockets pass their tw_priority
  field to tcp_v6_send_response() and tcp_v6_send_ack().
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Julian noted that rt_uses_gateway has a more subtle use than 'is gateway
set':
    https://lore.kernel.org/netdev/alpine.LFD.2.21.1909151104060.2546@ja.home.ssi.bg/

Revert that part of the commit referenced in the Fixes tag.

Currently, there are no u8 holes in 'struct rtable'. There is a 4-byte hole
in the second cacheline which contains the gateway declaration. So move
rt_gw_family down to the gateway declarations since they are always used
together, and then re-use that u8 for rt_uses_gateway. End result is that
rtable size is unchanged.

Fixes: 1550c171 ("ipv4: Prepare rtable for IPv6 gateway")
Reported-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Reviewed-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>

Enable setting skb->mark for UDP and RAW sockets using cmsg.

This is analogous to existing support for TOS, TTL, txtime, etc.

Packet sockets already support this as of commit c7d39e32
("packet: support per-packet fwmark for af_packet sendmsg").

Similar to other fields, implement by
1. initialize the sockcm_cookie.mark from socket option sk_mark
2. optionally overwrite this in ip_cmsg_send/ip6_datagram_send_ctl
3. initialize inet_cork.mark from sockcm_cookie.mark
4. initialize each (usually just one) skb->mark from inet_cork.mark

Step 1 is handled in one location for most protocols by ipcm_init_sk
as of commit 35178206 ("ipv4: ipcm_cookie initializers").
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Multicast or broadcast egress packets have rt_iif set to the oif. These
packets might be recirculated back as input and lookup to the raw
sockets may fail because they are bound to the incoming interface
(skb_iif). If rt_iif is not zero, during the lookup, inet_iif() function
returns rt_iif instead of skb_iif. Hence, the lookup fails.

v2: Make it non vrf specific (David Ahern). Reword the changelog to
    reflect it.
Signed-off-by: NStephen Suryaputra <ssuryaextr@gmail.com>
Reviewed-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If we want to set a EDT time for the skb we want to send
via ip_send_unicast_reply(), we have to pass a new parameter
and initialize ipc.sockc.transmit_time with it.

This fixes the EDT time for ACK/RST packets sent on behalf of
a TIME_WAIT socket.

Fixes: a842fe14 ("tcp: add optional per socket transmit delay")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The below patch fixes an incorrect zerocopy refcnt increment when
appending with MSG_MORE to an existing zerocopy udp skb.

  send(.., MSG_ZEROCOPY | MSG_MORE);	// refcnt 1
  send(.., MSG_ZEROCOPY | MSG_MORE);	// refcnt still 1 (bar frags)

But it missed that zerocopy need not be passed at the first send. The
right test whether the uarg is newly allocated and thus has extra
refcnt 1 is not !skb, but !skb_zcopy.

  send(.., MSG_MORE);			// <no uarg>
  send(.., MSG_ZEROCOPY);		// refcnt 1

Fixes: 100f6d8e ("net: correct zerocopy refcnt with udp MSG_MORE")
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

syzbot reported nasty use-after-free [1]

Lets remove frag_list field from structs ip_fraglist_iter
and ip6_fraglist_iter. This seens not needed anyway.

[1] :
BUG: KASAN: use-after-free in kfree_skb_list+0x5d/0x60 net/core/skbuff.c:706
Read of size 8 at addr ffff888085a3cbc0 by task syz-executor303/8947

CPU: 0 PID: 8947 Comm: syz-executor303 Not tainted 5.2.0-rc2+ #12
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 kfree_skb_list+0x5d/0x60 net/core/skbuff.c:706
 ip6_fragment+0x1ef4/0x2680 net/ipv6/ip6_output.c:882
 __ip6_finish_output+0x577/0xaa0 net/ipv6/ip6_output.c:144
 ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:156
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip6_output+0x235/0x7f0 net/ipv6/ip6_output.c:179
 dst_output include/net/dst.h:433 [inline]
 ip6_local_out+0xbb/0x1b0 net/ipv6/output_core.c:179
 ip6_send_skb+0xbb/0x350 net/ipv6/ip6_output.c:1796
 ip6_push_pending_frames+0xc8/0xf0 net/ipv6/ip6_output.c:1816
 rawv6_push_pending_frames net/ipv6/raw.c:617 [inline]
 rawv6_sendmsg+0x2993/0x35e0 net/ipv6/raw.c:947
 inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:802
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:671
 ___sys_sendmsg+0x803/0x920 net/socket.c:2292
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2330
 __do_sys_sendmsg net/socket.c:2339 [inline]
 __se_sys_sendmsg net/socket.c:2337 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44add9
Code: e8 7c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 1b 05 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f826f33bce8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006e7a18 RCX: 000000000044add9
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000005
RBP: 00000000006e7a10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e7a1c
R13: 00007ffcec4f7ebf R14: 00007f826f33c9c0 R15: 20c49ba5e353f7cf

Allocated by task 8947:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
 slab_post_alloc_hook mm/slab.h:437 [inline]
 slab_alloc_node mm/slab.c:3269 [inline]
 kmem_cache_alloc_node+0x131/0x710 mm/slab.c:3579
 __alloc_skb+0xd5/0x5e0 net/core/skbuff.c:199
 alloc_skb include/linux/skbuff.h:1058 [inline]
 __ip6_append_data.isra.0+0x2a24/0x3640 net/ipv6/ip6_output.c:1519
 ip6_append_data+0x1e5/0x320 net/ipv6/ip6_output.c:1688
 rawv6_sendmsg+0x1467/0x35e0 net/ipv6/raw.c:940
 inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:802
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:671
 ___sys_sendmsg+0x803/0x920 net/socket.c:2292
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2330
 __do_sys_sendmsg net/socket.c:2339 [inline]
 __se_sys_sendmsg net/socket.c:2337 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8947:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3698
 kfree_skbmem net/core/skbuff.c:625 [inline]
 kfree_skbmem+0xc5/0x150 net/core/skbuff.c:619
 __kfree_skb net/core/skbuff.c:682 [inline]
 kfree_skb net/core/skbuff.c:699 [inline]
 kfree_skb+0xf0/0x390 net/core/skbuff.c:693
 kfree_skb_list+0x44/0x60 net/core/skbuff.c:708
 __dev_xmit_skb net/core/dev.c:3551 [inline]
 __dev_queue_xmit+0x3034/0x36b0 net/core/dev.c:3850
 dev_queue_xmit+0x18/0x20 net/core/dev.c:3914
 neigh_direct_output+0x16/0x20 net/core/neighbour.c:1532
 neigh_output include/net/neighbour.h:511 [inline]
 ip6_finish_output2+0x1034/0x2550 net/ipv6/ip6_output.c:120
 ip6_fragment+0x1ebb/0x2680 net/ipv6/ip6_output.c:863
 __ip6_finish_output+0x577/0xaa0 net/ipv6/ip6_output.c:144
 ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:156
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip6_output+0x235/0x7f0 net/ipv6/ip6_output.c:179
 dst_output include/net/dst.h:433 [inline]
 ip6_local_out+0xbb/0x1b0 net/ipv6/output_core.c:179
 ip6_send_skb+0xbb/0x350 net/ipv6/ip6_output.c:1796
 ip6_push_pending_frames+0xc8/0xf0 net/ipv6/ip6_output.c:1816
 rawv6_push_pending_frames net/ipv6/raw.c:617 [inline]
 rawv6_sendmsg+0x2993/0x35e0 net/ipv6/raw.c:947
 inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:802
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:671
 ___sys_sendmsg+0x803/0x920 net/socket.c:2292
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2330
 __do_sys_sendmsg net/socket.c:2339 [inline]
 __se_sys_sendmsg net/socket.c:2337 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888085a3cbc0
 which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 0 bytes inside of
 224-byte region [ffff888085a3cbc0, ffff888085a3cca0)
The buggy address belongs to the page:
page:ffffea0002168f00 refcount:1 mapcount:0 mapping:ffff88821b6f63c0 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00027bbf88 ffffea0002105b88 ffff88821b6f63c0
raw: 0000000000000000 ffff888085a3c080 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888085a3ca80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888085a3cb00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>ffff888085a3cb80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                           ^
 ffff888085a3cc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888085a3cc80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc

Fixes: 0feca619 ("net: ipv6: add skbuff fraglist splitter")
Fixes: c8b17be0 ("net: ipv4: add skbuff fraglist splitter")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Update BPF_CGROUP_RUN_PROG_INET_EGRESS() callers to support returning
congestion notifications from the BPF programs.
Signed-off-by: NLawrence Brakmo <brakmo@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

TCP zerocopy takes a uarg reference for every skb, plus one for the
tcp_sendmsg_locked datapath temporarily, to avoid reaching refcnt zero
as it builds, sends and frees skbs inside its inner loop.

UDP and RAW zerocopy do not send inside the inner loop so do not need
the extra sock_zerocopy_get + sock_zerocopy_put pair. Commit
52900d22288ed ("udp: elide zerocopy operation in hot path") introduced
extra_uref to pass the initial reference taken in sock_zerocopy_alloc
to the first generated skb.

But, sock_zerocopy_realloc takes this extra reference at the start of
every call. With MSG_MORE, no new skb may be generated to attach the
extra_uref to, so refcnt is incorrectly 2 with only one skb.

Do not take the extra ref if uarg && !tcp, which implies MSG_MORE.
Update extra_uref accordingly.

This conditional assignment triggers a false positive may be used
uninitialized warning, so have to initialize extra_uref at define.

Changes v1->v2: fix typo in Fixes SHA1

Fixes: 52900d22 ("udp: elide zerocopy operation in hot path")
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Diagnosed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Deal with the IPCB() area away from the iterators.

The bridge codebase has its own control buffer layout, move specific
IP control buffer handling into the IPv4 codepath.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch exposes a new API to refragment a skbuff. This allows you to
split either a linear skbuff or to force the refragmentation of an
existing fraglist using a different mtu. The API consists of:

* ip_frag_init(), that initializes the internal state of the transformer.
* ip_frag_next(), that allows you to fetch the next fragment. This function
  internally allocates the skbuff that represents the fragment, it pushes
  the IPv4 header, and it also copies the payload for each fragment.

The ip_frag_state object stores the internal state of the splitter.

This code has been extracted from ip_do_fragment(). Symbols are also
exported to allow to reuse this iterator from the bridge codepath to
build its own refragmentation routine by reusing the existing codebase.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds the skbuff fraglist splitter. This API provides an
iterator to transform the fraglist into single skbuff objects, it
consists of:

* ip_fraglist_init(), that initializes the internal state of the
  fraglist splitter.
* ip_fraglist_prepare(), that restores the IPv4 header on the
  fragments.
* ip_fraglist_next(), that retrieves the fragment from the fraglist and
  it updates the internal state of the splitter to point to the next
  fragment skbuff in the fraglist.

The ip_fraglist_iter object stores the internal state of the iterator.

This code has been extracted from ip_do_fragment(). Symbols are also
exported to allow to reuse this iterator from the bridge codepath to
build its own refragmentation routine by reusing the existing codebase.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Previously, during fragmentation after forwarding, skb->skb_iif isn't
preserved, i.e. 'ip_copy_metadata' does not copy skb_iif from given
'from' skb.

As a result, ip_do_fragment's creates fragments with zero skb_iif,
leading to inconsistent behavior.

Assume for example an eBPF program attached at tc egress (post
forwarding) that examines __sk_buff->ingress_ifindex:
 - the correct iif is observed if forwarding path does not involve
   fragmentation/refragmentation
 - a bogus iif is observed if forwarding path involves
   fragmentation/refragmentatiom

Fix, by preserving skb_iif during 'ip_copy_metadata'.
Signed-off-by: NShmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A common theme in the output path is looking up a neigh entry for a
nexthop, either the gateway in an rtable or a fallback to the daddr
in the skb:

        nexthop = (__force u32)rt_nexthop(rt, ip_hdr(skb)->daddr);
        neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
        if (unlikely(!neigh))
                neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);

To allow the nexthop to be an IPv6 address we need to consider the
family of the nexthop and then call __ipv{4,6}_neigh_lookup_noref based
on it.

To make this simpler, add a ip_neigh_gw4 helper similar to ip_neigh_gw6
added in an earlier patch which handles:

        neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
        if (unlikely(!neigh))
                neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);

And then add a second one, ip_neigh_for_gw, that calls either
ip_neigh_gw4 or ip_neigh_gw6 based on the address family of the gateway.

Update the output paths in the VRF driver and core v4 code to use
ip_neigh_for_gw simplifying the family based lookup and making both
ready for a v6 nexthop.

ipv4_neigh_lookup has a different need - the potential to resolve a
passed in address in addition to any gateway in the rtable or skb. Since
this is a one-off, add ip_neigh_gw4 and ip_neigh_gw6 diectly. The
difference between __neigh_create used by the helpers and neigh_create
called by ipv4_neigh_lookup is taking a refcount, so add rcu_read_lock_bh
and bump the refcnt on the neigh entry.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A later patch allows an IPv6 gateway with an IPv4 route. The neighbor
entry will exist in the v6 ndisc table and the cached header will contain
the ipv6 protocol which is wrong for an IPv4 packet. For an IPv4 packet to
use the v6 neighbor entry, neigh_output needs to skip the cached header
and just use the output callback for the neigh entry.

A future patchset can look at expanding the hh_cache to handle 2
protocols. For now, IPv6 gateways with an IPv4 route will take the
extra overhead of generating the header.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To allow the gateway to be either an IPv4 or IPv6 address, remove
rt_uses_gateway from rtable and replace with rt_gw_family. If
rt_gw_family is set it implies rt_uses_gateway. Rename rt_gateway
to rt_gw4 to represent the IPv4 version.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Reviewed-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Just like 46cfd725 ("net: use kfree_skb_list() helper in more places").
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Acked-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This adds an optional extension infrastructure, with ispec (xfrm) and
bridge netfilter as first users.
objdiff shows no changes if kernel is built without xfrm and br_netfilter
support.

The third (planned future) user is Multipath TCP which is still
out-of-tree.
MPTCP needs to map logical mptcp sequence numbers to the tcp sequence
numbers used by individual subflows.

This DSS mapping is read/written from tcp option space on receive and
written to tcp option space on transmitted tcp packets that are part of
and MPTCP connection.

Extending skb_shared_info or adding a private data field to skb fclones
doesn't work for incoming skb, so a different DSS propagation method would
be required for the receive side.

mptcp has same requirements as secpath/bridge netfilter:

1. extension memory is released when the sk_buff is free'd.
2. data is shared after cloning an skb (clone inherits extension)
3. adding extension to an skb will COW the extension buffer if needed.

The "MPTCP upstreaming" effort adds SKB_EXT_MPTCP extension to store the
mapping for tx and rx processing.

Two new members are added to sk_buff:
1. 'active_extensions' byte (filling a hole), telling which extensions
   are available for this skb.
   This has two purposes.
   a) avoids the need to initialize the pointer.
   b) allows to "delete" an extension by clearing its bit
   value in ->active_extensions.

   While it would be possible to store the active_extensions byte
   in the extension struct instead of sk_buff, there is one problem
   with this:
    When an extension has to be disabled, we can always clear the
    bit in skb->active_extensions.  But in case it would be stored in the
    extension buffer itself, we might have to COW it first, if
    we are dealing with a cloned skb.  On kmalloc failure we would
    be unable to turn an extension off.

2. extension pointer, located at the end of the sk_buff.
   If the active_extensions byte is 0, the pointer is undefined,
   it is not initialized on skb allocation.

This adds extra code to skb clone and free paths (to deal with
refcount/free of extension area) but this replaces similar code that
manages skb->nf_bridge and skb->sp structs in the followup patches of
the series.

It is possible to add support for extensions that are not preseved on
clones/copies.

To do this, it would be needed to define a bitmask of all extensions that
need copy/cow semantics, and change __skb_ext_copy() to check
->active_extensions & SKB_EXT_PRESERVE_ON_CLONE, then just set
->active_extensions to 0 on the new clone.

This isn't done here because all extensions that get added here
need the copy/cow semantics.

v2:
Allocate entire extension space using kmem_cache.
Upside is that this allows better tracking of used memory,
downside is that we will allocate more space than strictly needed in
most cases (its unlikely that all extensions are active/needed at same
time for same skb).
The allocated memory (except the small extension header) is not cleared,
so no additonal overhead aside from memory usage.

Avoid atomic_dec_and_test operation on skb_ext_put()
by using similar trick as kfree_skbmem() does with fclone_ref:
If recount is 1, there is no concurrent user and we can free right away.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

extra_uref is used in __ip(6)_append_data only if uarg is set.

Smatch sees that the variable is passed to sock_zerocopy_put_abort.
This function accesses it only when uarg is set, but smatch cannot
infer this.

Make this dependency explicit.

Fixes: 52900d22 ("udp: elide zerocopy operation in hot path")
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With MSG_ZEROCOPY, each skb holds a reference to a struct ubuf_info.
Release of its last reference triggers a completion notification.

The TCP stack in tcp_sendmsg_locked holds an extra ref independent of
the skbs, because it can build, send and free skbs within its loop,
possibly reaching refcount zero and freeing the ubuf_info too soon.

The UDP stack currently also takes this extra ref, but does not need
it as all skbs are sent after return from __ip(6)_append_data.

Avoid the extra refcount_inc and refcount_dec_and_test, and generally
the sock_zerocopy_put in the common path, by passing the initial
reference to the first skb.

This approach is taken instead of initializing the refcount to 0, as
that would generate error "refcount_t: increment on 0" on the
next skb_zcopy_set.

Changes
  v3 -> v4
    - Move skb_zcopy_set below the only kfree_skb that might cause
      a premature uarg destroy before skb_zerocopy_put_abort
      - Move the entire skb_shinfo assignment block, to keep that
        cacheline access in one place
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Extend zerocopy to udp sockets. Allow setting sockopt SO_ZEROCOPY and
interpret flag MSG_ZEROCOPY.

This patch was previously part of the zerocopy RFC patchsets. Zerocopy
is not effective at small MTU. With segmentation offload building
larger datagrams, the benefit of page flipping outweights the cost of
generating a completion notification.

tools/testing/selftests/net/msg_zerocopy.sh after applying follow-on
test patch and making skb_orphan_frags_rx same as skb_orphan_frags:

    ipv4 udp -t 1
    tx=191312 (11938 MB) txc=0 zc=n
    rx=191312 (11938 MB)
    ipv4 udp -z -t 1
    tx=304507 (19002 MB) txc=304507 zc=y
    rx=304507 (19002 MB)
    ok
    ipv6 udp -t 1
    tx=174485 (10888 MB) txc=0 zc=n
    rx=174485 (10888 MB)
    ipv6 udp -z -t 1
    tx=294801 (18396 MB) txc=294801 zc=y
    rx=294801 (18396 MB)
    ok

Changes
  v1 -> v2
    - Fixup reverse christmas tree violation
  v2 -> v3
    - Split refcount avoidance optimization into separate patch
      - Fix refcount leak on error in fragmented case
        (thanks to Paolo Abeni for pointing this one out!)
      - Fix refcount inc on zero
      - Test sock_flag SOCK_ZEROCOPY directly in __ip_append_data.
        This is needed since commit 5cf4a853 ("tcp: really ignore
	MSG_ZEROCOPY if no SO_ZEROCOPY") did the same for tcp.
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In ip packet generation, pagedlen is initialized for each skb at the
start of the loop in __ip(6)_append_data, before label alloc_new_skb.

Depending on compiler options, code can be generated that jumps to
this label, triggering use of an an uninitialized variable.

In practice, at -O2, the generated code moves the initialization below
the label. But the code should not rely on that for correctness.

Fixes: 15e36f5b ("udp: paged allocation with gso")
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

An SKB is not on a list if skb->next is NULL.

Codify this convention into a helper function and use it
where we are dequeueing an SKB and need to mark it as such.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The skb hash for locally generated ip[v6] fragments belonging
to the same datagram can vary in several circumstances:
* for connected UDP[v6] sockets, the first fragment get its hash
  via set_owner_w()/skb_set_hash_from_sk()
* for unconnected IPv6 UDPv6 sockets, the first fragment can get
  its hash via ip6_make_flowlabel()/skb_get_hash_flowi6(), if
  auto_flowlabel is enabled

For the following frags the hash is usually computed via
skb_get_hash().
The above can cause OoO for unconnected IPv6 UDPv6 socket: in that
scenario the egress tx queue can be selected on a per packet basis
via the skb hash.
It may also fool flow-oriented schedulers to place fragments belonging
to the same datagram in different flows.

Fix the issue by copying the skb hash from the head frag into
the others at fragmentation time.

Before this commit:
perf probe -a "dev_queue_xmit skb skb->hash skb->l4_hash:b1@0/8 skb->sw_hash:b1@1/8"
netperf -H $IPV4 -t UDP_STREAM -l 5 -- -m 2000 -n &
perf record -e probe:dev_queue_xmit -e probe:skb_set_owner_w -a sleep 0.1
perf script
probe:dev_queue_xmit: (ffffffff8c6b1b20) hash=3713014309 l4_hash=1 sw_hash=0
probe:dev_queue_xmit: (ffffffff8c6b1b20) hash=0 l4_hash=0 sw_hash=0

After this commit:
probe:dev_queue_xmit: (ffffffff8c6b1b20) hash=2171763177 l4_hash=1 sw_hash=0
probe:dev_queue_xmit: (ffffffff8c6b1b20) hash=2171763177 l4_hash=1 sw_hash=0

Fixes: b73c3d0e ("net: Save TX flow hash in sock and set in skbuf on xmit")
Fixes: 67800f9b ("ipv6: Call skb_get_hash_flowi6 to get skb->hash in ip6_make_flowlabel")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that ipc(6)->gso_size is correctly initialized in all callers of
ip(6)_setup_cork, it is safe to unconditionally pass it to the cork.

Link: http://lkml.kernel.org/r/20180619164752.143249-1-willemdebruijn.kernel@gmail.comSigned-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

skb_shinfo(skb)->tx_flags is derived from sk->sk_tsflags, possibly
after modification by __sock_cmsg_send, by calling sock_tx_timestamp.

The IPv4 and IPv6 paths do this conversion differently. In IPv4, the
individual protocols that support tx timestamps call this function
and store the result in ipc.tx_flags. In IPv6, sock_tx_timestamp is
called in __ip6_append_data.

There is no need to store both tx_flags and ts_flags in the cookie
as one is derived from the other. Convert when setting up the cork
and remove the redundant field. This is similar to IPv6, only have
the conversion happen only once per datagram, in ip(6)_setup_cork.

Also change __ip6_append_data to match __ip_append_data. Only update
tskey if timestamping is enabled with OPT_ID. The SOCK_.. test is
redundant: only valid protocols can have non-zero cork->tx_flags.

After this change the IPv4 and IPv6 logic is the same.
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initialize the cookie in one location to reduce code duplication and
avoid bugs from inconsistent initialization, such as that fixed in
commit 9887cba1 ("ip: limit use of gso_size to udp").
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a transmit_time field to struct inet_cork, then copy the
timestamp from the CMSG cookie at ip_setup_cork() so we can
safely copy it into the skb later during __ip_make_skb().

For the raw fast path, just perform the copy at raw_send_hdrinc().
Signed-off-by: NRichard Cochran <rcochran@linutronix.de>
Signed-off-by: NJesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces __ip_queue_xmit(), through which the callers
can pass tos param into it without having to set inet->tos. For
ipv6, ip6_xmit() already allows passing tclass parameter.

It's needed when some transport protocol doesn't use inet->tos,
like sctp's per transport dscp, which will be added in next patch.
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The ipcm(6)_cookie field gso_size is set only in the udp path. The ip
layer copies this to cork only if sk_type is SOCK_DGRAM. This check
proved too permissive. Ping and l2tp sockets have the same type.

Limit to sockets of type SOCK_DGRAM and protocol IPPROTO_UDP to
exclude ping sockets.

v1 -> v2
- remove irrelevant whitespace changes

Fixes: bec1f6f6 ("udp: generate gso with UDP_SEGMENT")
Reported-by: NMaciej Żenczykowski <maze@google.com>
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Device features may change during transmission. In particular with
corking, a device may toggle scatter-gather in between allocating
and writing to an skb.

Do not unconditionally assume that !NETIF_F_SG at write time implies
that the same held at alloc time and thus the skb has sufficient
tailroom.

This issue predates git history.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This version has some suggestions by Eric Dumazet:

- Use a local variable for the mark in IPv6 instead of ctl_sk to avoid SMP
races.
- Use the more elegant "IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark"
statement.
- Factorize code as sk_fullsock() check is not necessary.

Aidan McGurn from Openwave Mobility systems reported the following bug:

"Marked routing is broken on customer deployment. Its effects are large
increase in Uplink retransmissions caused by the client never receiving
the final ACK to their FINACK - this ACK misses the mark and routes out
of the incorrect route."

Currently marks are added to sk_buffs for replies when the "fwmark_reflect"
sysctl is enabled. But not for TW sockets that had sk->sk_mark set via
setsockopt(SO_MARK..).

Fix this in IPv4/v6 by adding tw->tw_mark for TIME_WAIT sockets. Copy the the
original sk->sk_mark in __inet_twsk_hashdance() to the new tw->tw_mark location.
Then progate this so that the skb gets sent with the correct mark. Do the same
for resets. Give the "fwmark_reflect" sysctl precedence over sk->sk_mark so that
netfilter rules are still honored.
Signed-off-by: NJon Maxwell <jmaxwell37@gmail.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When sending large datagrams that are later segmented, store data in
page frags to avoid copying from linear in skb_segment.
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>