kernel/linux.git/include/net/udp.h, branch v5.15.209

net: drop UFO packets in udp_rcv_segment()

2025-08-28T14:24:13+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().

2023-04-26T11:51:54+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.

2022-11-10T17:15:38+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.

2022-07-29T15:25:22+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

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

2021-10-26T12:09:22+00:00

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

skmsg: Pass psock pointer to ->psock_update_sk_prot()

2021-04-12T15:34:27+00:00

Using sk_psock() to retrieve psock pointer from sock requires RCU read lock, but we already get psock pointer before calling ->psock_update_sk_prot() in both cases, so we can just pass it without bothering sk_psock(). Fixes: 8a59f9d1e3d4 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()") Reported-by: syzbot+320a3bc8d80f478c37e4@syzkaller.appspotmail.com Signed-off-by: Cong Wang Signed-off-by: Daniel Borkmann Tested-by: syzbot+320a3bc8d80f478c37e4@syzkaller.appspotmail.com Reviewed-by: Jakub Sitnicki Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20210407032111.33398-1-xiyou.wangcong@gmail.com

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2021-04-02T18:03:07+00:00

Alexei Starovoitov says: ==================== pull-request: bpf-next 2021-04-01 The following pull-request contains BPF updates for your *net-next* tree. We've added 68 non-merge commits during the last 7 day(s) which contain a total of 70 files changed, 2944 insertions(+), 1139 deletions(-). The main changes are: 1) UDP support for sockmap, from Cong. 2) Verifier merge conflict resolution fix, from Daniel. 3) xsk selftests enhancements, from Maciej. 4) Unstable helpers aka kernel func calling, from Martin. 5) Batches ops for LPM map, from Pedro. 6) Fix race in bpf_get_local_storage, from Yonghong. ==================== Signed-off-by: David S. Miller

udp: Implement ->read_sock() for sockmap

2021-04-01T17:56:14+00:00

This is similar to tcp_read_sock(), except we do not need to worry about connections, we just need to retrieve skb from UDP receive queue. Note, the return value of ->read_sock() is unused in sk_psock_verdict_data_ready(), and UDP still does not support splice() due to lack of ->splice_read(), so users can not reach udp_read_sock() directly. Signed-off-by: Cong Wang Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20210331023237.41094-12-xiyou.wangcong@gmail.com

sock: Introduce sk->sk_prot->psock_update_sk_prot()

2021-04-01T17:56:14+00:00

Currently sockmap calls into each protocol to update the struct proto and replace it. This certainly won't work when the protocol is implemented as a module, for example, AF_UNIX. Introduce a new ops sk->sk_prot->psock_update_sk_prot(), so each protocol can implement its own way to replace the struct proto. This also helps get rid of symbol dependencies on CONFIG_INET. Signed-off-by: Cong Wang Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210331023237.41094-11-xiyou.wangcong@gmail.com

udp: fixup csum for GSO receive slow path

2021-03-31T00:06:49+00:00

When UDP packets generated locally by a socket with UDP_SEGMENT traverse the following path: UDP tunnel(xmit) -> veth (segmentation) -> veth (gro) -> UDP tunnel (rx) -> UDP socket (no UDP_GRO) ip_summed will be set to CHECKSUM_PARTIAL at creation time and such checksum mode will be preserved in the above path up to the UDP tunnel receive code where we have: __iptunnel_pull_header() -> skb_pull_rcsum() -> skb_postpull_rcsum() -> __skb_postpull_rcsum() The latter will convert the skb to CHECKSUM_NONE. The UDP GSO packet will be later segmented as part of the rx socket receive operation, and will present a CHECKSUM_NONE after segmentation. Additionally the segmented packets UDP CB still refers to the original GSO packet len. Overall that causes unexpected/wrong csum validation errors later in the UDP receive path. We could possibly address the issue with some additional checks and csum mangling in the UDP tunnel code. Since the issue affects only this UDP receive slow path, let's set a suitable csum status there. Note that SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST packets lacking an UDP encapsulation present a valid checksum when landing to udp_queue_rcv_skb(), as the UDP checksum has been validated by the GRO engine. v2 -> v3: - even more verbose commit message and comments v1 -> v2: - restrict the csum update to the packets strictly needing them - hopefully clarify the commit message and code comments Signed-off-by: Paolo Abeni Reviewed-by: Willem de Bruijn Signed-off-by: David S. Miller