kernel/linux.git/include/linux/skbuff.h, branch v6.12.93

net: Introduce skb tc depth field to track packet loops

2026-06-09T10:25:43+00:00

[ Upstream commit 98b34f3e8c3492cfc89ff943c9d92b4d52863d1d ] Add a 2-bit per-skb tc depth field to track packet loops across the stack. The previous per-CPU loop counters like MIRRED_NEST_LIMIT assume a single call stack and lose state in two cases: 1) When a packet is queued and reprocessed later (e.g., egress->ingress via backlog), the per-cpu state is gone by the time it is dequeued. 2) With XPS/RPS a packet may arrive on one CPU and be processed on another. A per-skb field solves both by travelling with the packet itself. The field fits in existing padding, using 2 bits that were previously a hole: pahole before(-) and after (+) diff looks like: __u8 slow_gro:1; /* 132: 3 1 */ __u8 csum_not_inet:1; /* 132: 4 1 */ __u8 unreadable:1; /* 132: 5 1 */ + __u8 tc_depth:2; /* 132: 6 1 */ - /* XXX 2 bits hole, try to pack */ /* XXX 1 byte hole, try to pack */ __u16 tc_index; /* 134 2 */ There used to be a ttl field which was removed as part of tc_verd in commit aec745e2c520 ("net-tc: remove unused tc_verd fields"). It was already unused by that time, due to remove earlier in commit c19ae86a510c ("tc: remove unused redirect ttl"). The first user of this field is netem, which increments tc_depth on duplicated packets before re-enqueueing them at the root qdisc. On re-entry, netem skips duplication for any skb with tc_depth already set, bounding recursion to a single level regardless of tree topology. The other user is mirred which increments it on each pass and limits to depth to MIRRED_DEFER_LIMIT (3). The new field was called ttl in earlier versions of this patch but renamed to tc_depth to avoid confusion with IP ttl. Note (looking at you Sashiko! Dont ignore me and continue bringing this up): 1. Since both mirred and netem utilize the same 2-bit tc_depth field it is possible when netem and mirred are used together that netem qdisc to skip the duplication step. This is a known trade-off, as a 2-bit field cannot independently track both features' recursion depths and it is not considered sane to have a setup that addresses both features on at the same time. 2. skb_scrub_packet does not clear tc_depth. This means a packet's loop history is preserved even across namespaces. While this might be restrictive for some topologies, it is also design intent to provide robustness against loops across namespaces. Reviewed-by: Stephen Hemminger Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260525122556.973584-2-jhs@mojatatu.com Signed-off-by: Paolo Abeni Stable-dep-of: e80ad525fc7e ("net/sched: act_mirred: Fix return code in early mirred redirect error paths") Signed-off-by: Sasha Levin

net: Add skb_dstref_steal and skb_dstref_restore

2026-03-04T12:20:11+00:00

[ Upstream commit c3f0c02997c7f8489fec259e28e0e04e9811edac ] Going forward skb_dst_set will assert that skb dst_entry is empty during skb_dst_set to prevent potential leaks. There are few places that still manually manage dst_entry not using the helpers. Convert them to the following new helpers: - skb_dstref_steal that resets dst_entry and returns previous dst_entry value - skb_dstref_restore that restores dst_entry previously reset via skb_dstref_steal Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20250818154032.3173645-2-sdf@fomichev.me Signed-off-by: Jakub Kicinski Stable-dep-of: 81b84de32bb2 ("xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path") Signed-off-by: Sasha Levin

net: add skb_header_pointer_careful() helper

2026-02-11T12:40:24+00:00

[ Upstream commit 13e00fdc9236bd4d0bff4109d2983171fbcb74c4 ] This variant of skb_header_pointer() should be used in contexts where @offset argument is user-controlled and could be negative. Negative offsets are supported, as long as the zone starts between skb->head and skb->data. Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260128141539.3404400-2-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: cabd1a976375 ("net/sched: cls_u32: use skb_header_pointer_careful()") Signed-off-by: Sasha Levin

net: Introduce skb_copy_datagram_from_iter_full()

2026-01-30T09:28:49+00:00

[Upstream commit b08a784a5d1495c42ff9b0c70887d49211cddfe0] In a similar manner to copy_from_iter()/copy_from_iter_full(), introduce skb_copy_datagram_from_iter_full() which reverts the iterator to its initial state when returning an error. A subsequent fix for a vsock regression will make use of this new function. Cc: Christian Brauner Cc: Alexander Viro Signed-off-by: Will Deacon Acked-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi Link: https://patch.msgid.link/20250818180355.29275-2-will@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Heitor Alves de Siqueira Signed-off-by: Greg Kroah-Hartman

net: skb: add pskb_network_may_pull_reason() helper

2025-09-09T16:58:10+00:00

[ Upstream commit 454bbde8f0d465e93e5a3a4003ac6c7e62fa4473 ] Introduce the function pskb_network_may_pull_reason() and make pskb_network_may_pull() a simple inline call to it. The drop reasons of it just come from pskb_may_pull_reason. Signed-off-by: Menglong Dong Reviewed-by: Simon Horman Signed-off-by: David S. Miller Stable-dep-of: 6ead38147ebb ("vxlan: Fix NPD when refreshing an FDB entry with a nexthop object") Signed-off-by: Sasha Levin

netmem: fix skb_frag_address_safe with unreadable skbs

2025-08-20T16:30:36+00:00

[ Upstream commit 4672aec56d2e8edabcb74c3e2320301d106a377e ] skb_frag_address_safe() needs a check that the skb_frag_page exists check similar to skb_frag_address(). Cc: ap420073@gmail.com Signed-off-by: Mina Almasry Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250619175239.3039329-1-almasrymina@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: reject malicious packets in ipv6_gso_segment()

2025-08-15T10:14:06+00:00

[ Upstream commit d45cf1e7d7180256e17c9ce88e32e8061a7887fe ] syzbot was able to craft a packet with very long IPv6 extension headers leading to an overflow of skb->transport_header. This 16bit field has a limited range. Add skb_reset_transport_header_careful() helper and use it from ipv6_gso_segment() WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 skb_reset_transport_header include/linux/skbuff.h:3032 [inline] WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 Modules linked in: CPU: 0 UID: 0 PID: 5871 Comm: syz-executor211 Not tainted 6.16.0-rc6-syzkaller-g7abc678e3084 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:skb_reset_transport_header include/linux/skbuff.h:3032 [inline] RIP: 0010:ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 Call Trace: skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 nsh_gso_segment+0x54a/0xe10 net/nsh/nsh.c:110 skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 __skb_gso_segment+0x342/0x510 net/core/gso.c:124 skb_gso_segment include/net/gso.h:83 [inline] validate_xmit_skb+0x857/0x11b0 net/core/dev.c:3950 validate_xmit_skb_list+0x84/0x120 net/core/dev.c:4000 sch_direct_xmit+0xd3/0x4b0 net/sched/sch_generic.c:329 __dev_xmit_skb net/core/dev.c:4102 [inline] __dev_queue_xmit+0x17b6/0x3a70 net/core/dev.c:4679 Fixes: d1da932ed4ec ("ipv6: Separate ipv6 offload support") Reported-by: syzbot+af43e647fd835acc02df@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/688a1a05.050a0220.5d226.0008.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Reviewed-by: Dawid Osuchowski Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250730131738.3385939-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: add support for skbs with unreadable frags

2024-09-12T03:44:31+00:00

For device memory TCP, we expect the skb headers to be available in host memory for access, and we expect the skb frags to be in device memory and unaccessible to the host. We expect there to be no mixing and matching of device memory frags (unaccessible) with host memory frags (accessible) in the same skb. Add a skb->devmem flag which indicates whether the frags in this skb are device memory frags or not. __skb_fill_netmem_desc() now checks frags added to skbs for net_iov, and marks the skb as skb->devmem accordingly. Add checks through the network stack to avoid accessing the frags of devmem skbs and avoid coalescing devmem skbs with non devmem skbs. Signed-off-by: Willem de Bruijn Signed-off-by: Kaiyuan Zhang Signed-off-by: Mina Almasry Reviewed-by: Eric Dumazet Reviewed-by: Jakub Kicinski Link: https://patch.msgid.link/20240910171458.219195-9-almasrymina@google.com Signed-off-by: Jakub Kicinski

net: support non paged skb frags

2024-09-12T03:44:31+00:00

Make skb_frag_page() fail in the case where the frag is not backed by a page, and fix its relevant callers to handle this case. Signed-off-by: Mina Almasry Reviewed-by: Eric Dumazet Reviewed-by: Jakub Kicinski Link: https://patch.msgid.link/20240910171458.219195-8-almasrymina@google.com Signed-off-by: Jakub Kicinski

Merge tag 'ipsec-next-2024-09-10' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next

2024-09-11T02:00:47+00:00

Steffen Klassert says: ==================== pull request (net-next): ipsec-next 2024-09-10 1) Remove an unneeded WARN_ON on packet offload. From Patrisious Haddad. 2) Add a copy from skb_seq_state to buffer function. This is needed for the upcomming IPTFS patchset. From Christian Hopps. 3) Spelling fix in xfrm.h. From Simon Horman. 4) Speed up xfrm policy insertions. From Florian Westphal. 5) Add and revert a patch to support xfrm interfaces for packet offload. This patch was just half cooked. 6) Extend usage of the new xfrm_policy_is_dead_or_sk helper. From Florian Westphal. 7) Update comments on sdb and xfrm_policy. From Florian Westphal. 8) Fix a null pointer dereference in the new policy insertion code From Florian Westphal. 9) Fix an uninitialized variable in the new policy insertion code. From Nathan Chancellor. * tag 'ipsec-next-2024-09-10' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next: xfrm: policy: Restore dir assignments in xfrm_hash_rebuild() xfrm: policy: fix null dereference Revert "xfrm: add SA information to the offloaded packet" xfrm: minor update to sdb and xfrm_policy comments xfrm: policy: use recently added helper in more places xfrm: add SA information to the offloaded packet xfrm: policy: remove remaining use of inexact list xfrm: switch migrate to xfrm_policy_lookup_bytype xfrm: policy: don't iterate inexact policies twice at insert time selftests: add xfrm policy insertion speed test script xfrm: Correct spelling in xfrm.h net: add copy from skb_seq_state to buffer function xfrm: Remove documentation WARN_ON to limit return values for offloaded SA ==================== Link: https://patch.msgid.link/20240910065507.2436394-1-steffen.klassert@secunet.com Signed-off-by: Jakub Kicinski