linux-stable.git/include/net/udp.h, branch linux-5.4.y

net: drop UFO packets in udp_rcv_segment()

2025-08-28T14:21:22+00:00

[ Upstream commit d46e51f1c78b9ab9323610feb14238d06d46d519 ]

When sending a packet with virtio_net_hdr to tun device, if the gso_type
in virtio_net_hdr is SKB_GSO_UDP and the gso_size is less than udphdr
size, below crash may happen.

  ------------[ cut here ]------------
  kernel BUG at net/core/skbuff.c:4572!
  Oops: invalid opcode: 0000 [#1] SMP NOPTI
  CPU: 0 UID: 0 PID: 62 Comm: mytest Not tainted 6.16.0-rc7 #203 PREEMPT(voluntary)
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
  RIP: 0010:skb_pull_rcsum+0x8e/0xa0
  Code: 00 00 5b c3 cc cc cc cc 8b 93 88 00 00 00 f7 da e8 37 44 38 00 f7 d8 89 83 88 00 00 00 48 8b 83 c8 00 00 00 5b c3 cc cc cc cc <0f> 0b 0f 0b 66 66 2e 0f 1f 84 00 000
  RSP: 0018:ffffc900001fba38 EFLAGS: 00000297
  RAX: 0000000000000004 RBX: ffff8880040c1000 RCX: ffffc900001fb948
  RDX: ffff888003e6d700 RSI: 0000000000000008 RDI: ffff88800411a062
  RBP: ffff8880040c1000 R08: 0000000000000000 R09: 0000000000000001
  R10: ffff888003606c00 R11: 0000000000000001 R12: 0000000000000000
  R13: ffff888004060900 R14: ffff888004050000 R15: ffff888004060900
  FS:  000000002406d3c0(0000) GS:ffff888084a19000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000020000040 CR3: 0000000004007000 CR4: 00000000000006f0
  Call Trace:
   
   udp_queue_rcv_one_skb+0x176/0x4b0 net/ipv4/udp.c:2445
   udp_queue_rcv_skb+0x155/0x1f0 net/ipv4/udp.c:2475
   udp_unicast_rcv_skb+0x71/0x90 net/ipv4/udp.c:2626
   __udp4_lib_rcv+0x433/0xb00 net/ipv4/udp.c:2690
   ip_protocol_deliver_rcu+0xa6/0x160 net/ipv4/ip_input.c:205
   ip_local_deliver_finish+0x72/0x90 net/ipv4/ip_input.c:233
   ip_sublist_rcv_finish+0x5f/0x70 net/ipv4/ip_input.c:579
   ip_sublist_rcv+0x122/0x1b0 net/ipv4/ip_input.c:636
   ip_list_rcv+0xf7/0x130 net/ipv4/ip_input.c:670
   __netif_receive_skb_list_core+0x21d/0x240 net/core/dev.c:6067
   netif_receive_skb_list_internal+0x186/0x2b0 net/core/dev.c:6210
   napi_complete_done+0x78/0x180 net/core/dev.c:6580
   tun_get_user+0xa63/0x1120 drivers/net/tun.c:1909
   tun_chr_write_iter+0x65/0xb0 drivers/net/tun.c:1984
   vfs_write+0x300/0x420 fs/read_write.c:593
   ksys_write+0x60/0xd0 fs/read_write.c:686
   do_syscall_64+0x50/0x1c0 arch/x86/entry/syscall_64.c:63
   

To trigger gso segment in udp_queue_rcv_skb(), we should also set option
UDP_ENCAP_ESPINUDP to enable udp_sk(sk)->encap_rcv. When the encap_rcv
hook return 1 in udp_queue_rcv_one_skb(), udp_csum_pull_header() will try
to pull udphdr, but the skb size has been segmented to gso size, which
leads to this crash.

Previous commit cf329aa42b66 ("udp: cope with UDP GRO packet misdirection")
introduces segmentation in UDP receive path only for GRO, which was never
intended to be used for UFO, so drop UFO packets in udp_rcv_segment().

Link: https://lore.kernel.org/netdev/20250724083005.3918375-1-wangliang74@huawei.com/
Link: https://lore.kernel.org/netdev/20250729123907.3318425-1-wangliang74@huawei.com/
Fixes: cf329aa42b66 ("udp: cope with UDP GRO packet misdirection")
Suggested-by: Willem de Bruijn 
Signed-off-by: Wang Liang 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20250730101458.3470788-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct().

2023-04-26T09:24:05+00:00

commit d38afeec26ed4739c640bf286c270559aab2ba5f upstream.

Originally, inet6_sk(sk)->XXX were changed under lock_sock(), so we were
able to clean them up by calling inet6_destroy_sock() during the IPv6 ->
IPv4 conversion by IPV6_ADDRFORM.  However, commit 03485f2adcde ("udpv6:
Add lockless sendmsg() support") added a lockless memory allocation path,
which could cause a memory leak:

setsockopt(IPV6_ADDRFORM)                 sendmsg()
+-----------------------+                 +-------+
- do_ipv6_setsockopt(sk, ...)             - udpv6_sendmsg(sk, ...)
  - sockopt_lock_sock(sk)                   ^._ called via udpv6_prot
    - lock_sock(sk)                             before WRITE_ONCE()
  - WRITE_ONCE(sk->sk_prot, &tcp_prot)
  - inet6_destroy_sock()                    - if (!corkreq)
  - sockopt_release_sock(sk)                  - ip6_make_skb(sk, ...)
    - release_sock(sk)                          ^._ lockless fast path for
                                                    the non-corking case

                                                - __ip6_append_data(sk, ...)
                                                  - ipv6_local_rxpmtu(sk, ...)
                                                    - xchg(&np->rxpmtu, skb)
                                                      ^._ rxpmtu is never freed.

                                                - goto out_no_dst;

                                            - lock_sock(sk)

For now, rxpmtu is only the case, but not to miss the future change
and a similar bug fixed in commit e27326009a3d ("net: ping6: Fix
memleak in ipv6_renew_options()."), let's set a new function to IPv6
sk->sk_destruct() and call inet6_cleanup_sock() there.  Since the
conversion does not change sk->sk_destruct(), we can guarantee that
we can clean up IPv6 resources finally.

We can now remove all inet6_destroy_sock() calls from IPv6 protocol
specific ->destroy() functions, but such changes are invasive to
backport.  So they can be posted as a follow-up later for net-next.

Fixes: 03485f2adcde ("udpv6: Add lockless sendmsg() support")
Signed-off-by: Kuniyuki Iwashima 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Ziyang Xuan 
Signed-off-by: Greg Kroah-Hartman

tcp/udp: Make early_demux back namespacified.

2022-11-10T16:57:55+00:00

commit 11052589cf5c0bab3b4884d423d5f60c38fcf25d upstream.

Commit e21145a9871a ("ipv4: namespacify ip_early_demux sysctl knob") made
it possible to enable/disable early_demux on a per-netns basis.  Then, we
introduced two knobs, tcp_early_demux and udp_early_demux, to switch it for
TCP/UDP in commit dddb64bcb346 ("net: Add sysctl to toggle early demux for
tcp and udp").  However, the .proc_handler() was wrong and actually
disabled us from changing the behaviour in each netns.

We can execute early_demux if net.ipv4.ip_early_demux is on and each proto
.early_demux() handler is not NULL.  When we toggle (tcp|udp)_early_demux,
the change itself is saved in each netns variable, but the .early_demux()
handler is a global variable, so the handler is switched based on the
init_net's sysctl variable.  Thus, netns (tcp|udp)_early_demux knobs have
nothing to do with the logic.  Whether we CAN execute proto .early_demux()
is always decided by init_net's sysctl knob, and whether we DO it or not is
by each netns ip_early_demux knob.

This patch namespacifies (tcp|udp)_early_demux again.  For now, the users
of the .early_demux() handler are TCP and UDP only, and they are called
directly to avoid retpoline.  So, we can remove the .early_demux() handler
from inet6?_protos and need not dereference them in ip6?_rcv_finish_core().
If another proto needs .early_demux(), we can restore it at that time.

Fixes: dddb64bcb346 ("net: Add sysctl to toggle early demux for tcp and udp")
Signed-off-by: Kuniyuki Iwashima 
Link: https://lore.kernel.org/r/20220713175207.7727-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

udp: Fix a data-race around sysctl_udp_l3mdev_accept.

2022-07-29T15:14:14+00:00

[ Upstream commit 3d72bb4188c708bb16758c60822fc4dda7a95174 ]

While reading sysctl_udp_l3mdev_accept, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 63a6fff353d0 ("net: Avoid receiving packets with an l3mdev on unbound UDP sockets")
Signed-off-by: Kuniyuki Iwashima 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

udp: call udp_encap_enable for v6 sockets when enabling encap

2022-04-15T12:18:01+00:00

commit a4a600dd301ccde6ea239804ec1f19364a39d643 upstream.

When enabling encap for a ipv6 socket without udp_encap_needed_key
increased, UDP GRO won't work for v4 mapped v6 address packets as
sk will be NULL in udp4_gro_receive().

This patch is to enable it by increasing udp_encap_needed_key for
v6 sockets in udp_tunnel_encap_enable(), and correspondingly
decrease udp_encap_needed_key in udpv6_destroy_sock().

v1->v2:
  - add udp_encap_disable() and export it.
v2->v3:
  - add the change for rxrpc and bareudp into one patch, as Alex
    suggested.
v3->v4:
  - move rxrpc part to another patch.

Acked-by: Willem de Bruijn 
Signed-off-by: Xin Long 
Signed-off-by: Jakub Kicinski 
Tested-by: Antonio Quartulli 
Signed-off-by: Greg Kroah-Hartman

net: multicast: calculate csum of looped-back and forwarded packets

2021-11-17T08:48:21+00:00

[ Upstream commit 9122a70a6333705c0c35614ddc51c274ed1d3637 ]

During a testing of an user-space application which transmits UDP
multicast datagrams and utilizes multicast routing to send the UDP
datagrams out of defined network interfaces, I've found a multicast
router does not fill-in UDP checksum into locally produced, looped-back
and forwarded UDP datagrams, if an original output NIC the datagrams
are sent to has UDP TX checksum offload enabled.

The datagrams are sent malformed out of the NIC the datagrams have been
forwarded to.

It is because:

1. If TX checksum offload is enabled on the output NIC, UDP checksum
   is not calculated by kernel and is not filled into skb data.

2. dev_loopback_xmit(), which is called solely by
   ip_mc_finish_output(), sets skb->ip_summed = CHECKSUM_UNNECESSARY
   unconditionally.

3. Since 35fc92a9 ("[NET]: Allow forwarding of ip_summed except
   CHECKSUM_COMPLETE"), the ip_summed value is preserved during
   forwarding.

4. If ip_summed != CHECKSUM_PARTIAL, checksum is not calculated during
   a packet egress.

The minimum fix in dev_loopback_xmit():

1. Preserves skb->ip_summed CHECKSUM_PARTIAL. This is the
   case when the original output NIC has TX checksum offload enabled.
   The effects are:

     a) If the forwarding destination interface supports TX checksum
        offloading, the NIC driver is responsible to fill-in the
        checksum.

     b) If the forwarding destination interface does NOT support TX
        checksum offloading, checksums are filled-in by kernel before
        skb is submitted to the NIC driver.

     c) For local delivery, checksum validation is skipped as in the
        case of CHECKSUM_UNNECESSARY, thanks to skb_csum_unnecessary().

2. Translates ip_summed CHECKSUM_NONE to CHECKSUM_UNNECESSARY. It
   means, for CHECKSUM_NONE, the behavior is unmodified and is there
   to skip a looped-back packet local delivery checksum validation.

Signed-off-by: Cyril Strejc 
Reviewed-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

udp: document udp_rcv_segment special case for looped packets

2020-05-10T08:31:33+00:00

commit d0208bf4da97f76237300afb83c097de25645de6 upstream.

Commit 6cd021a58c18a ("udp: segment looped gso packets correctly")
fixes an issue with rare udp gso multicast packets looped onto the
receive path.

The stable backport makes the narrowest change to target only these
packets, when needed. As opposed to, say, expanding __udp_gso_segment,
which is harder to reason to be free from unintended side-effects.

But the resulting code is hardly self-describing.
Document its purpose and rationale.

Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

udp: segment looped gso packets correctly

2020-02-01T09:34:39+00:00

[ Upstream commit 6cd021a58c18a1731f7e47f83e172c0c302d65e5 ]

Multicast and broadcast packets can be looped from egress to ingress
pre segmentation with dev_loopback_xmit. That function unconditionally
sets ip_summed to CHECKSUM_UNNECESSARY.

udp_rcv_segment segments gso packets in the udp rx path. Segmentation
usually executes on egress, and does not expect packets of this type.
__udp_gso_segment interprets !CHECKSUM_PARTIAL as CHECKSUM_NONE. But
the offsets are not correct for gso_make_checksum.

UDP GSO packets are of type CHECKSUM_PARTIAL, with their uh->check set
to the correct pseudo header checksum. Reset ip_summed to this type.
(CHECKSUM_PARTIAL is allowed on ingress, see comments in skbuff.h)

Reported-by: syzbot 
Fixes: cf329aa42b66 ("udp: cope with UDP GRO packet misdirection")
Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

udp: Remove unlikely() from IS_ERR*() condition

2019-08-31T02:49:37+00:00

"unlikely(IS_ERR_OR_NULL(x))" is excessive. IS_ERR_OR_NULL() already uses
unlikely() internally.

Signed-off-by: Denis Efremov 
Cc: "David S. Miller" 
Cc: Joe Perches 
Cc: Andrew Morton 
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller

Merge tag 'spdx-5.2-rc3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2019-05-31T15:34:32+00:00

Pull yet more SPDX updates from Greg KH:
 "Here is another set of reviewed patches that adds SPDX tags to
  different kernel files, based on a set of rules that are being used to
  parse the comments to try to determine that the license of the file is
  "GPL-2.0-or-later" or "GPL-2.0-only". Only the "obvious" versions of
  these matches are included here, a number of "non-obvious" variants of
  text have been found but those have been postponed for later review
  and analysis.

  There is also a patch in here to add the proper SPDX header to a bunch
  of Kbuild files that we have missed in the past due to new files being
  added and forgetting that Kbuild uses two different file names for
  Makefiles. This issue was reported by the Kbuild maintainer.

  These patches have been out for review on the linux-spdx@vger mailing
  list, and while they were created by automatic tools, they were
  hand-verified by a bunch of different people, all whom names are on
  the patches are reviewers"

* tag 'spdx-5.2-rc3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (82 commits)
  treewide: Add SPDX license identifier - Kbuild
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 225
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 224
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 223
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 222
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 221
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 220
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 218
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 217
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 216
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 215
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 214
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 213
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 211
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 210
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 209
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 207
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 203
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 201
  ...