kernel.git/net/ipv6/udp.c, branch linux-rolling-stable

net: Convert proto callbacks from sockaddr to sockaddr_unsized

2025-11-05T03:10:33Z

Convert struct proto pre_connect(), connect(), bind(), and bind_add() callback function prototypes from struct sockaddr to struct sockaddr_unsized. This does not change per-implementation use of sockaddr for passing around an arbitrarily sized sockaddr struct. Those will be addressed in future patches. Additionally removes the no longer referenced struct sockaddr from include/net/inet_common.h. No binary changes expected. Signed-off-by: Kees Cook Link: https://patch.msgid.link/20251104002617.2752303-5-kees@kernel.org Signed-off-by: Jakub Kicinski

udp: remove busylock and add per NUMA queues

2025-09-23T23:38:39Z

busylock was protecting UDP sockets against packet floods, but unfortunately was not protecting the host itself. Under stress, many cpus could spin while acquiring the busylock, and NIC had to drop packets. Or packets would be dropped in cpu backlog if RPS/RFS were in place. This patch replaces the busylock by intermediate lockless queues. (One queue per NUMA node). This means that fewer number of cpus have to acquire the UDP receive queue lock. Most of the cpus can either: - immediately drop the packet. - or queue it in their NUMA aware lockless queue. Then one of the cpu is chosen to process this lockless queue in a batch. The batch only contains packets that were cooked on the same NUMA node, thus with very limited latency impact. Tested: DDOS targeting a victim UDP socket, on a platform with 6 NUMA nodes (Intel(R) Xeon(R) 6985P-C) Before: nstat -n ; sleep 1 ; nstat | grep Udp Udp6InDatagrams 1004179 0.0 Udp6InErrors 3117 0.0 Udp6RcvbufErrors 3117 0.0 After: nstat -n ; sleep 1 ; nstat | grep Udp Udp6InDatagrams 1116633 0.0 Udp6InErrors 14197275 0.0 Udp6RcvbufErrors 14197275 0.0 We can see this host can now proces 14.2 M more packets per second while under attack, and the victim socket can receive 11 % more packets. I used a small bpftrace program measuring time (in us) spent in __udp_enqueue_schedule_skb(). Before: @udp_enqueue_us[398]: [0] 24901 |@@@ | [1] 63512 |@@@@@@@@@ | [2, 4) 344827 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [4, 8) 244673 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ | [8, 16) 54022 |@@@@@@@@ | [16, 32) 222134 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ | [32, 64) 232042 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ | [64, 128) 4219 | | [128, 256) 188 | | After: @udp_enqueue_us[398]: [0] 5608855 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [1] 1111277 |@@@@@@@@@@ | [2, 4) 501439 |@@@@ | [4, 8) 102921 | | [8, 16) 29895 | | [16, 32) 43500 | | [32, 64) 31552 | | [64, 128) 979 | | [128, 256) 13 | | Note that the remaining bottleneck for this platform is in udp_drops_inc() because we limited struct numa_drop_counters to only two nodes so far. Signed-off-by: Eric Dumazet Acked-by: Paolo Abeni Reviewed-by: Willem de Bruijn Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250922104240.2182559-1-edumazet@google.com Signed-off-by: Jakub Kicinski

udp: add udp_drops_inc() helper

2025-09-18T08:17:10Z

Generic sk_drops_inc() reads sk->sk_drop_counters. We know the precise location for UDP sockets. Move sk_drop_counters out of sock_read_rxtx so that sock_write_rxtx starts at a cache line boundary. Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250916160951.541279-9-edumazet@google.com Reviewed-by: Jakub Kicinski Signed-off-by: Paolo Abeni

ipv6: np->rxpmtu race annotation

2025-09-18T08:17:09Z

Add READ_ONCE() annotations because np->rxpmtu can be changed while udpv6_recvmsg() and rawv6_recvmsg() read it. Since this is a very rarely used feature, and that udpv6_recvmsg() and rawv6_recvmsg() read np->rxopt anyway, change the test order so that np->rxpmtu does not need to be in a hot cache line. Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250916160951.541279-4-edumazet@google.com Reviewed-by: Jakub Kicinski Signed-off-by: Paolo Abeni

ipv6: udp: fix typos in comments

2025-09-12T01:41:58Z

Correct typos in ipv6/udp.c comments: "execeeds" -> "exceeds" "tacking care" -> "taking care" "measureable" -> "measurable" No functional changes. Signed-off-by: Alok Tiwari Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250909122611.3711859-1-alok.a.tiwari@oracle.com Signed-off-by: Jakub Kicinski

net: add sk_drops_read(), sk_drops_inc() and sk_drops_reset() helpers

2025-08-28T11:14:50Z

We want to split sk->sk_drops in the future to reduce potential contention on this field. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250826125031.1578842-2-edumazet@google.com Signed-off-by: Paolo Abeni

net: track pfmemalloc drops via SKB_DROP_REASON_PFMEMALLOC

2025-07-18T23:59:05Z

Add a new SKB drop reason (SKB_DROP_REASON_PFMEMALLOC) to track packets dropped due to memory pressure. In production environments, we've observed memory exhaustion reported by memory layer stack traces, but these drops were not properly tracked in the SKB drop reason infrastructure. While most network code paths now properly report pfmemalloc drops, some protocol-specific socket implementations still use sk_filter() without drop reason tracking: - Bluetooth L2CAP sockets - CAIF sockets - IUCV sockets - Netlink sockets - SCTP sockets - Unix domain sockets These remaining cases represent less common paths and could be converted in a follow-up patch if needed. The current implementation provides significantly improved observability into memory pressure events in the network stack, especially for key protocols like TCP and UDP, helping to diagnose problems in production environments. Reported-by: Matt Fleming Signed-off-by: Jesper Dangaard Brouer Link: https://patch.msgid.link/175268316579.2407873.11634752355644843509.stgit@firesoul Signed-off-by: Jakub Kicinski

udp: move udp_memory_allocated into net_aligned_data

2025-07-02T21:22:02Z

____cacheline_aligned_in_smp attribute only makes sure to align a field to a cache line. It does not prevent the linker to use the remaining of the cache line for other variables, causing potential false sharing. Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250630093540.3052835-5-edumazet@google.com Signed-off-by: Jakub Kicinski

net: annotate races around sk->sk_uid

2025-06-24T00:04:03Z

sk->sk_uid can be read while another thread changes its value in sockfs_setattr(). Add sk_uid(const struct sock *sk) helper to factorize the needed READ_ONCE() annotations, and add corresponding WRITE_ONCE() where needed. Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.") Signed-off-by: Eric Dumazet Cc: Lorenzo Colitti Reviewed-by: Maciej Żenczykowski Link: https://patch.msgid.link/20250620133001.4090592-2-edumazet@google.com Signed-off-by: Jakub Kicinski

udp_tunnel: create a fastpath GRO lookup.

2025-04-09T01:19:41Z

Most UDP tunnels bind a socket to a local port, with ANY address, no peer and no interface index specified. Additionally it's quite common to have a single tunnel device per namespace. Track in each namespace the UDP tunnel socket respecting the above. When only a single one is present, store a reference in the netns. When such reference is not NULL, UDP tunnel GRO lookup just need to match the incoming packet destination port vs the socket local port. The tunnel socket never sets the reuse[port] flag[s]. When bound to no address and interface, no other socket can exist in the same netns matching the specified local port. Matching packets with non-local destination addresses will be aggregated, and eventually segmented as needed - no behavior changes intended. Restrict the optimization to kernel sockets only: it covers all the relevant use-cases, and user-space owned sockets could be disconnected and rebound after setup_udp_tunnel_sock(), breaking the uniqueness assumption Note that the UDP tunnel socket reference is stored into struct netns_ipv4 for both IPv4 and IPv6 tunnels. That is intentional to keep all the fastpath-related netns fields in the same struct and allow cacheline-based optimization. Currently both the IPv4 and IPv6 socket pointer share the same cacheline as the `udp_table` field. Signed-off-by: Paolo Abeni Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/41d16bc8d1257d567f9344c445b4ae0b4a91ede4.1744040675.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski