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2026-05-22netfilter: nf_tables: fix dst corruption in same register operationFernando Fernandez Mancera2-7/+24
For lshift and rshift, the shift operations are performed in a loop over 32-bit words. The loop calculates the shifted value and write it to dst, and then immediately reads from src to calculate the carry for the next iteration. Because src and dst could point to the same memory location, the carry is incorrectly calculated using the newly modified dst value instead of the original src value. Adding a temporary local variable to cache the original value before writing to dst and using it for the carry calculation solves the problem. In addition, partial overlap is rejected from control plane for all kind of operations including byteorder. This was tested with the following bytecode: table test_table ip flags 0 use 1 handle 1 ip test_table test_chain use 3 type filter hook input prio 0 policy accept packets 0 bytes 0 flags 1 ip test_table test_chain 2 [ immediate reg 1 0x44332211 0x88776655 ] [ bitwise reg 1 = ( reg 1 << 0x08000000 ) ] [ cmp eq reg 1 0x66443322 0x00887766 ] [ counter pkts 0 bytes 0 ] ip test_table test_chain 4 3 [ immediate reg 1 0x44332211 0x88776655 ] [ bitwise reg 1 = ( reg 1 << 0x08000000 ) ] [ cmp eq reg 1 0x55443322 0x00887766 ] [ counter pkts 21794 bytes 1917798 ] Fixes: 567d746b55bc ("netfilter: bitwise: add support for shifts.") Acked-by: Jeremy Sowden <jeremy@azazel.net> Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-22netfilter: disable payload mangling in usernsFlorian Westphal2-2/+7
Several parts of network stack rely on iph->ihl validation done by network stack before PRE_ROUTING. Disable this feature for user namespaces for now. tcp option handling is likely safe even for LOCAL_IN, so this this leaves tcp option mangling via nft_exthdr.c as-is. I don't think these are the only means to alter packets, but these appear to be relatively prominent. This could be relaxed later. Example: - allow userns for ingress hook. - allow userns if base is transport header. Also, we should revalidate or restrict generally: - Don't allow linklayer writes to spill into network header - restrict ipv4 and ipv6 to 'known safe' writes, e.g. saddr/daddr/check/tos Reported-by: Qi Tang <tpluszz77@gmail.com> Reported-by: Tong Liu <lyutoon@gmail.com> Tested-by: Qi Tang <tpluszz77@gmail.com> Link: https://lore.kernel.org/netfilter-devel/20260515100411.3141-1-fw@strlen.de/ Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-22netfilter: xt_cpu: prefer raw_smp_processor_idFlorian Westphal1-1/+1
With PREEMPT_RCU we get splat: BUG: using smp_processor_id() in preemptible [..] caller is cpu_mt+0x53/0xd0 net/netfilter/xt_cpu.c:37 CPU: 1 .. Comm: syz.3.1377 #0 PREEMPT(full) Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 check_preemption_disabled+0xd3/0xe0 lib/smp_processor_id.c:47 cpu_mt+0x53/0xd0 net/netfilter/xt_cpu.c:37 [..] Just use raw version instead. This is similar to 14d14a5d2957 ("netfilter: nft_meta: use raw_smp_processor_id()"). Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables") Reported-by: syzbot+690d3e3ffa7335ac10eb@syzkaller.appspotmail.com Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-22netfilter: nf_conntrack_gre: fix gre keymap list corruptionFlorian Westphal3-30/+90
Quoting reporter: A race between GRE keymap insertion and destruction can corrupt the kernel list or use a freed object. `nf_ct_gre_keymap_add()` publishes a new keymap pointer before the embedded `list_head` is linked, while `nf_ct_gre_keymap_destroy()` can concurrently delete and free that same object. An unprivileged user can reach this through the PPTP conntrack helper by racing PPTP control messages or helper teardown, leading to KASAN-detectable list corruption/UAF in kernel context. ## Root Cause Analysis `exp_gre()` installs GRE expectations for a PPTP control flow and then adds two GRE keymap entries [..] The add path publishes `ct_pptp_info->keymap[dir]` before linking the embedded list node [..] Concurrent teardown deletes that partially initialized object. Make add/destroy symmetric: install both, destroy both while under lock. Furthermore, we should refuse to publish a new mapping in case ct is going away, else we may leak the allocation. The "retrans" detection is strange: existing mapping is checked for key equality with the new mapping, then for "is on the list" via list walk. But I can't see how an existing keymap entry can be NOT on list. Change this to only check if we're asked to map same tuple again -- if so, skip re-install, else signal failure. Last, add a bug trap for the keymap list; it has to be empty when namespace is going away. Reported-by: Leo Lin <leo@depthfirst.com> Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-22netfilter: synproxy: refresh tcphdr after skb_ensure_writableChris Mason1-0/+2
synproxy_tstamp_adjust() rewrites the TCP timestamp option in place and then patches the TCP checksum via inet_proto_csum_replace4() on the caller-supplied tcphdr pointer. Both ipv4_synproxy_hook() and ipv6_synproxy_hook() obtain that pointer with skb_header_pointer() before calling in, so it may either alias skb->head directly or point at the caller's on-stack _tcph buffer. Between obtaining the pointer and using it, the function calls skb_ensure_writable(skb, optend), which on a cloned or non-linear skb invokes pskb_expand_head() and frees the old skb->head. After that point the cached th is stale: caller (ipv[46]_synproxy_hook) th = skb_header_pointer(skb, ..., &_tcph) synproxy_tstamp_adjust(skb, protoff, th, ...) skb_ensure_writable(skb, optend) pskb_expand_head() /* kfree(old skb->head) */ ... inet_proto_csum_replace4(&th->check, ...) /* writes into freed head, or into the caller's stack copy leaving the on-wire checksum stale */ The option bytes are written through skb->data and are fine; only the checksum update goes through th and so lands in the wrong place. The result is either a write into freed slab memory or a packet leaving with a checksum that does not match its payload. Fix by re-deriving th from skb->data + protoff immediately after skb_ensure_writable() succeeds, so the subsequent checksum update targets the linear, writable header. Fixes: 48b1de4c110a ("netfilter: add SYNPROXY core/target") Assisted-by: kres (claude-opus-4-7) Signed-off-by: Chris Mason <clm@meta.com> Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-22netfilter: conntrack: tcp: do not force CLOSE on invalid-seq RST without direction checkHamza Mahfooz1-1/+2
An unintended behavior in the TCP conntrack state machine allows a connection to be forced into the CLOSE state using an RST packet with an invalid sequence number. Specifically, after a SYN packet is observed, an RST with an invalid SEQ can transition the conntrack entry to TCP_CONNTRACK_CLOSE, regardless of whether the RST corresponds to the expected reply direction. The relevant code path assumes the RST is a response to an outgoing SYN, but does not validate packet direction or ensure that a matching SYN was actually sent in the opposite direction. As a result, a crafted packet sequence consisting of a SYN followed by an invalid-sequence RST can prematurely terminate an active NAT entry. This makes connection teardown easier than intended. So, tighten the state transition logic to ensure that RST-triggered CLOSE transitions only occur when the RST is a valid response to a previously observed SYN in the correct direction. Cc: stable@vger.kernel.org Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.") Signed-off-by: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-16netfilter: nf_queue: hold bridge skb->dev while queuedHaoze Xie2-1/+5
br_pass_frame_up() rewrites skb->dev from the ingress port to the bridge master before queueing bridge LOCAL_IN packets. NFQUEUE only holds references on state.in/out and bridge physdevs, so a queued bridge packet can retain a freed bridge master in skb->dev until reinjection. When the verdict is reinjected later, br_netif_receive_skb() re-enters the receive path with skb->dev still pointing at the freed bridge master, triggering a use-after-free. Store skb->dev in the queue entry, hold a reference on it for the queue lifetime, and use the saved device when dropping queued packets during NETDEV_DOWN handling. Fixes: ac2863445686 ("netfilter: bridge: add nf_afinfo to enable queuing to userspace") Cc: stable@kernel.org Reported-by: Yuan Tan <yuantan098@gmail.com> Reported-by: Yifan Wu <yifanwucs@gmail.com> Reported-by: Juefei Pu <tomapufckgml@gmail.com> Reported-by: Xin Liu <bird@lzu.edu.cn> Signed-off-by: Haoze Xie <royenheart@gmail.com> Signed-off-by: Ren Wei <n05ec@lzu.edu.cn> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: ipset: annotate "pos" for concurrent readers/writersJozsef Kadlecsik1-24/+38
The "pos" structure member of struct hbucket stores the first free slot in the hash bucket of a hash type of set and there are concurrent readers/writers. Annotate accesses properly. Fixes: 18f84d41d34f ("netfilter: ipset: Introduce RCU locking in hash:* types") Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: ipset: Fix data race between add and dump in all hash typesJozsef Kadlecsik1-2/+5
When adding a new entry to the next position in the existing hash bucket, the position index was incremented too early and parallel dump could read it before the entry was populated with the value. Move the setting of the position index after populating the entry. v2: Position counting fixed, noticed by Florian Westphal. Fixes: 18f84d41d34f ("netfilter: ipset: Introduce RCU locking in hash:* types") Reported-by: syzbot+786c889f046e8b003ca6@syzkaller.appspotmail.com Reported-by: syzbot+1da17e4b41d795df059e@syzkaller.appspotmail.com Reported-by: syzbot+421c5f3ff8e9493084d9@syzkaller.appspotmail.com Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: ipset: Fix data race between add and list header in all hash typesJozsef Kadlecsik1-2/+2
The "ipset list -terse" command is actually a dump operation which may run parallel with "ipset add" commands, which can trigger an internal resizing of the hash type of sets just being dumped. However, dumping just the header part of the set was not protected against underlying resizing. Fix it by protecting the header dumping part as well. Fixes: c4c997839cf9 ("netfilter: ipset: Fix parallel resizing and listing of the same set") Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: nft_inner: release local_lock before re-enabling softirqsFlorian Westphal1-1/+1
Quoting sashiko: In the error path, local_bh_enable() is called before local_unlock_nested_bh(). Fixes: ba36fada9ab4 ("netfilter: nft_inner: Use nested-BH locking for nft_pcpu_tun_ctx") Signed-off-by: Florian Westphal <fw@strlen.de> Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: ipset: stop hash:* range iteration at endNan Li4-4/+17
The following hash set variants: hash:ip,mark hash:ip,port hash:ip,port,ip hash:ip,port,net iterate IPv4 ranges with a 32-bit iterator. The iterator must stop once the last address in the requested range has been processed. Advancing it once more can move the traversal state past the end of the request, so a later retry may continue from an unintended position. Handle the iterator increment explicitly at the end of the loop and stop once the upper bound has been processed. This keeps the existing retry behaviour intact for valid ranges while preventing traversal from continuing past the original boundary. Fixes: 48596a8ddc46 ("netfilter: ipset: Fix adding an IPv4 range containing more than 2^31 addresses") Cc: stable@kernel.org Reported-by: Yuan Tan <yuantan098@gmail.com> Reported-by: Yifan Wu <yifanwucs@gmail.com> Reported-by: Juefei Pu <tomapufckgml@gmail.com> Reported-by: Xin Liu <bird@lzu.edu.cn> Signed-off-by: Nan Li <tonanli66@gmail.com> Signed-off-by: Ren Wei <n05ec@lzu.edu.cn> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: nft_inner: Fix IPv6 inner_thoff desyncYizhou Zhao1-1/+0
In nft_inner_parse_l2l3(), when processing inner IPv6 packets, ipv6_find_hdr() correctly computes the transport header offset traversing all extension headers, but the result is immediately overwritten with nhoff + sizeof(_ip6h) (40 bytes), which only accounts for the IPv6 base header. This creates a desync between inner_thoff (wrong — points to extension header start) and l4proto (correct — e.g., IPPROTO_TCP), enabling transport header forgery and potential firewall bypass. This issue affects stable versions from Linux 6.2. For comparison, the normal (non-inner) IPv6 path correctly preserves ipv6_find_hdr()'s result. Removing the incorrect overwrite ensures that ipv6_find_hdr()'s calculated transport header offset is preserved, thereby fixing the desynchronization. Fixes: 3a07327d10a0 ("netfilter: nft_inner: support for inner tunnel header matching") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn> Reported-by: Yuxiang Yang <yangyx22@mails.tsinghua.edu.cn> Reported-by: Xuewei Feng <fengxw06@126.com> Reported-by: Qi Li <qli01@tsinghua.edu.cn> Reported-by: Ke Xu <xuke@tsinghua.edu.cn> Assisted-by: GLM:5.1 Z.ai Signed-off-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn> Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: ipset: fix a potential dump-destroy raceJozsef Kadlecsik1-0/+1
When dumping sets in order to create the proper order for restore, the list type of sets dumped last. Therefore internally we run the dumping loop twice: first with all non-list type of sets and skipping the list type ones and then secondly for the list type of sets. Sashiko noticed that there's a potential race between dump and destroy if in the first loop the last set was a list type of set: its pointer remains unreferenced and a concurrent destroy can free it. Fix the issue by resetting the variable holding the pointer. Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16ipvs: avoid possible loop in ip_vs_dst_event on resizingJulian Anastasov1-65/+122
Sashiko points out that unprivileged user can frequently call ip_vs_flush() or ip_vs_del_service() to trigger svc_table_changes updates that can lead to infinite loop in ip_vs_dst_event(). This can also happen if the user triggers frequent table resizing without deleting all services. We should also consider the possible effects if the user triggers many NETDEV_DOWN events. One way to solve it is to hold svc_resize_sem in ip_vs_dst_event() but this can block the dev notifier during the whole resizing process. Instead, use new rw_semaphore svc_replace_sem to protect just the svc_table replacement which is a short code section. Then hold svc_replace_sem in ip_vs_dst_event() to serialize with replacing the svc_table. As result, loop is avoided as there is no need to repeat the table walking from the start. By this way changes in svc_table_changes can happen only when all services are removed and all dev references dropped which allows us to abort the table walking. As IP_VS_WORK_SVC_NORESIZE is the flag used to stop the svc_resize_work under service_mutex, we should check only this flag often but not while under service_mutex. To remove the mutex_trylock() for service_mutex in the second phase where the resizer installs the new table after rehashing, we will avoid holding the service_mutex there. As result, the code in configuration context which is under service_mutex should access ipvs->svc_table under RCU because it can be replaced at anytime and released after a RCU grace period. As for ip_vs_zero_all(), it needs different solution as a table walker which can escape single RCU read-side critical section: to hold the svc_replace_sem to prevent table to be replaced. In ip_vs_status_show() prefer to hold svc_replace_sem to avoid many loops, just detect if the svc_table is removed. Prefer the newly attached table for the u_thresh/l_thresh checks to know when to grow/shrink while adding or deleting services because the new table size is based on the latest parameters. Link: https://sashiko.dev/#/patchset/20260505001648.360569-1-pablo%40netfilter.org Fixes: 840aac3d900d ("ipvs: use resizable hash table for services") Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16netfilter: nf_conntrack_helper: fix possible null deref during error logFlorian Westphal1-5/+8
Reported by sashiko: there is a small race window. If a helper module is unloaded or a userspace-defined helper is removed, nf_conntrack_helper_unregister() sets ->helper to NULL. Handle this safely. This needs a second patch to close related race during nf_conntrack_helper_unregister(). Fixes: b20ab9cc63ca ("netfilter: nf_ct_helper: better logging for dropped packets") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: nft_ct: fix missing expect put in obj evalLi Xiasong1-0/+2
nft_ct_expect_obj_eval() allocates an expectation and may call nf_ct_expect_related(), but never drops its local reference. Add nf_ct_expect_put(exp) before return to balance allocation. Fixes: 857b46027d6f ("netfilter: nft_ct: add ct expectations support") Cc: stable@vger.kernel.org Signed-off-by: Li Xiasong <lixiasong1@huawei.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: nf_conntrack_sip: get helper before allocating expectationLi Xiasong1-4/+4
process_register_request() allocates an expectation and then checks whether a conntrack helper is available. If helper lookup fails, the function returns early and the allocated expectation is left behind. Reorder the code to fetch and validate helper before calling nf_ct_expect_alloc(). This keeps the logic simpler and removes the leak path while preserving existing behavior. Fixes: e14575fa7529 ("netfilter: nf_conntrack: use rcu accessors where needed") Cc: stable@vger.kernel.org Signed-off-by: Li Xiasong <lixiasong1@huawei.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: ctnetlink: check tuple and mask in expectations created via nfqueuePablo Neira Ayuso1-0/+3
Ensure the expectation tuple and mask attributes are present in netlink message, otherwise null-ptr-deref is possible. Fixes: bd0779370588 ("netfilter: nfnetlink_queue: allow to attach expectations to conntracks") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: nf_conntrack_expect: restore helper propagation via expectationPablo Neira Ayuso7-11/+35
A recent series to fix expectations broke helper propagation via expectation, this mechanism is used by the sip and h323 helper. This also propagates the conntrack helper to expected connections. I changed semantics of exp->helper which now tells us the actual helper that created the expectation. Add an explicit assign_helper field to expectations for this purpose and update helpers to use it. Restore this feature for userspace conntrack helper via ctnetlink nfqueue integration so it is again possible to attach a helper to an expectation, where it makes sense. This is not restored via ctnetlink expectation creation as there is no client for such feature. Use the expectation layer 4 protocol number for the helper lookup for consistency. Make sure the expectation using this helper propagation mechanism also go away when the helper is unregistered. Fixes: 9c42bc9db90a ("netfilter: nf_conntrack_expect: honor expectation helper field") Fixes: 917b61fa2042 ("netfilter: ctnetlink: ignore explicit helper on new expectations") Reported-by: Ilya Maximets <i.maximets@ovn.org> Tested-by: Ilya Maximets <i.maximets@ovn.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: x_tables: add and use xtables_unregister_table_exitFlorian Westphal1-19/+62
Previous change added xtables_unregister_table_pre_exit to detach the table from the packetpath and to unlink it from the active table list. In case of rmmod, userspace that is doing set/getsockopt for this table will not be able to re-instantiate the table: 1. The larval table has been removed already 2. existing instantiated table is no longer on the xt pernet table list. This adds the second stage helper: unlink the table from the dying list, free the hook ops (if any) and do the audit notification. It replaces xt_unregister_table(). Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default") Reported-by: Tristan Madani <tristan@talencesecurity.com> Reviewed-by: Tristan Madani <tristan@talencesecurity.com> Closes: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/ Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: x_tables: add and use xt_unregister_table_pre_exitFlorian Westphal1-0/+29
Remove the copypasted variants of _pre_exit and add one single function in the xtables core. ebtables is not compatible with x_tables and therefore unchanged. This is a preparation patch to reduce noise in the followup bug fixes. Reviewed-by: Tristan Madani <tristan@talencesecurity.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: x_tables: allocate hook ops while under mutexFlorian Westphal1-8/+42
arp/ip(6)t_register_table() add the table to the per-netns list via xt_register_table() before allocating the per-netns hook ops copy via kmemdup_array(). This leaves a window where the table is visible in the list with ops=NULL. If the pernet exit happens runs concurrently the pre_exit callback finds the table via xt_find_table() and passes the NULL ops pointer to nf_unregister_net_hooks(), causing a NULL dereference: general protection fault in nf_unregister_net_hooks+0xbc/0x150 RIP: nf_unregister_net_hooks (net/netfilter/core.c:613) Call Trace: ipt_unregister_table_pre_exit iptable_mangle_net_pre_exit ops_pre_exit_list cleanup_net Fix by moving the ops allocation into the xtables core so the table is never in the list without valid ops. Also ensure the table is no longer processing packets before its torn down on error unwind. nf_register_net_hooks might have published at least one hook; call synchronize_rcu() if there was an error. audit log register message gets deferred until all operations have passed, this avoids need to emit another ureg message in case of error unwinding. Based on earlier patch by Tristan Madani. Fixes: f9006acc8dfe5 ("netfilter: arp_tables: pass table pointer via nf_hook_ops") Fixes: ee177a54413a ("netfilter: ip6_tables: pass table pointer via nf_hook_ops") Fixes: ae689334225f ("netfilter: ip_tables: pass table pointer via nf_hook_ops") Link: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/ Signed-off-by: Tristan Madani <tristan@talencesecurity.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-08netfilter: x_tables: allow initial table replace without emitting audit log messageFlorian Westphal1-9/+20
At the moment we emit the audit log a bit too early, which makes it necessary to also emit an unregister log in case we have to unwind errors after possible hook register failure. Followup patch will be slightly simpler if we can delay the register message until after the hooks have been wired up. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-05ipvs: Guard access of HK_TYPE_KTHREAD cpumask with RCUWaiman Long1-5/+8
The ip_vs_ctl.c file and the associated ip_vs.h file are the only places in the kernel where HK_TYPE_KTHREAD cpumask is being retrieved and used. Now that HK_TYPE_KTHREAD/HK_TYPE_DOMAIN cpumask can be changed at run time. We need to use RCU to guard access to this cpumask to avoid a potential UAF problem as the returned cpumask may be freed before it is being used. We can replace HK_TYPE_KTHREAD by HK_TYPE_DOMAIN as they are aliases of each other, but keeping the HK_TYPE_KTHREAD name can highlight the fact that it is the kthread initiated by ipvs that is being controlled. Fixes: 03ff73510169 ("cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset") Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-05ipvs: fix shift-out-of-bounds in ip_vs_rht_desired_sizeJulian Anastasov1-1/+1
Calling roundup_pow_of_two() with 0 has undefined result: UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13 shift exponent 64 is too large for 64-bit type 'unsigned long' CPU: 1 UID: 0 PID: 77 Comm: kworker/u8:4 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: events_unbound conn_resize_work_handler Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233 __ubsan_handle_shift_out_of_bounds+0x385/0x410 lib/ubsan.c:494 __roundup_pow_of_two include/linux/log2.h:57 [inline] ip_vs_rht_desired_size+0x2cf/0x410 net/netfilter/ipvs/ip_vs_core.c:240 ip_vs_conn_desired_size net/netfilter/ipvs/ip_vs_conn.c:765 [inline] conn_resize_work_handler+0x1b6/0x14c0 net/netfilter/ipvs/ip_vs_conn.c:822 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> Reported-by: syzbot+217f1db9c791e27fe54a@syzkaller.appspotmail.com Fixes: b655388111cf ("ipvs: add resizable hash tables") Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-05ipvs: fix races around est_mutex and est_cpulistJulian Anastasov2-44/+90
Sashiko reports for races and possible crash around the usage of est_cpulist_valid and sysctl_est_cpulist. The problem is that we do not lock est_mutex in some places which can lead to wrong write ordering and as result problems when calling cpumask_weight() and cpumask_empty(). Fix them by moving the est_max_threads read/write under locked est_mutex. Do the same for one ip_vs_est_reload_start() call to protect the cpumask_empty() usage of sysctl_est_cpulist. To remove the chance of deadlock while stopping the estimation kthreads, keep the data structure for kthread 0 even after last estimator is removed and do not hold mutexes while stopping this task. Now we will use a new flag 'needed' to know when kthread 0 should run. The kthreads above 0 do not use mutexes, so stop them under est_mutex because their kthread data still can be destroyed if they do not serve estimators. Now all kthreads will be started by the est_reload_work to properly serialize the stop/start for kthread 0. Reduce the use of service_mutex in ip_vs_est_calc_phase() because under est_mutex we can safely walk est_kt_arr to stop the kthreads above slot 0. As ip_vs_stop_estimator() for tot_stats should be called under service_mutex, do it early in the netns exit path in ip_vs_flush() to avoid locking the mutex again later. It still should be called in ip_vs_control_net_cleanup_sysctl() when we are called during netns init error. Use -2 for ktid as indicator if estimator was already stopped. Finally, fix use-after-free for kd->est_row in ip_vs_est_calc_phase(). est->ktrow should simply switch to a delay value while estimator is linked to est_temp_list. Link: https://sashiko.dev/#/patchset/20260331165015.2777765-1-longman%40redhat.com Link: https://sashiko.dev/#/patchset/20260420171308.87192-1-ja%40ssi.bg Link: https://sashiko.dev/#/patchset/20260422125123.40658-1-ja%40ssi.bg Link: https://sashiko.dev/#/patchset/20260424175858.54752-1-ja%40ssi.bg Link: https://sashiko.dev/#/patchset/20260425103918.7447-1-ja%40ssi.bg Fixes: f0be83d54217 ("ipvs: add est_cpulist and est_nice sysctl vars") Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-05ipvs: do not leak dest after get from dest trashJulian Anastasov1-13/+24
Sashiko warns about leaked dest if ip_vs_start_estimator() fails in ip_vs_add_dest(). Add ip_vs_trash_put_dest() to put back the dest into dest trash. Link: https://sashiko.dev/#/patchset/20260428175725.72050-1-ja%40ssi.bg Fixes: 705dd3444081 ("ipvs: use kthreads for stats estimation") Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-05ipvs: fix the spin_lock usage for RT buildJulian Anastasov1-32/+40
syzbot reports for sleeping function called from invalid context [1]. The recently added code for resizable hash tables uses hlist_bl bit locks in combination with spin_lock for the connection fields (cp->lock). Fix the following problems: * avoid using spin_lock(&cp->lock) under locked bit lock because it sleeps on PREEMPT_RT * as the recent changes call ip_vs_conn_hash() only for newly allocated connection, the spin_lock can be removed there because the connection is still not linked to table and does not need cp->lock protection. * the lock can be removed also from ip_vs_conn_unlink() where we are the last connection user. * the last place that is fixed is ip_vs_conn_fill_cport() where now the cp->lock is locked before the other locks to ensure other packets do not modify the cp->flags in non-atomic way. Here we make sure cport and flags are changed only once if two or more packets race to fill the cport. Also, we fill cport early, so that if we race with resizing there will be valid cport key for the hashing. Add a warning if too many hash table changes occur for our RCU read-side critical section which is error condition but minor because the connection still can expire gracefully. Still, restore the cport to 0 to allow retransmitted packet to properly fill the cport. Problems reported by Sashiko. [1]: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 16, name: ktimers/0 preempt_count: 2, expected: 0 RCU nest depth: 3, expected: 3 8 locks held by ktimers/0/16: #0: ffffffff8de5f260 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #1: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #2: ffff8880b8826360 (&base->expiry_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #2: ffff8880b8826360 (&base->expiry_lock){+...}-{3:3}, at: timer_base_lock_expiry kernel/time/timer.c:1502 [inline] #2: ffff8880b8826360 (&base->expiry_lock){+...}-{3:3}, at: __run_timer_base+0x120/0x9f0 kernel/time/timer.c:2384 #3: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #3: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #3: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #3: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 #4: ffffc90000157a80 ((&cp->timer)){+...}-{0:0}, at: call_timer_fn+0xd4/0x5e0 kernel/time/timer.c:1745 #5: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #5: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #5: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: ip_vs_conn_unlink net/netfilter/ipvs/ip_vs_conn.c:315 [inline] #5: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: ip_vs_conn_expire+0x257/0x2390 net/netfilter/ipvs/ip_vs_conn.c:1260 #6: ffffffff8de5f260 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163 #7: ffff888068d4c3f0 (&cp->lock#2){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #7: ffff888068d4c3f0 (&cp->lock#2){+...}-{3:3}, at: ip_vs_conn_unlink net/netfilter/ipvs/ip_vs_conn.c:324 [inline] #7: ffff888068d4c3f0 (&cp->lock#2){+...}-{3:3}, at: ip_vs_conn_expire+0xd4a/0x2390 net/netfilter/ipvs/ip_vs_conn.c:1260 Preemption disabled at: [<ffffffff898a6358>] bit_spin_lock include/linux/bit_spinlock.h:38 [inline] [<ffffffff898a6358>] hlist_bl_lock+0x18/0x110 include/linux/list_bl.h:149 CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G W L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [W]=WARN, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 __might_resched+0x329/0x480 kernel/sched/core.c:9162 __rt_spin_lock kernel/locking/spinlock_rt.c:48 [inline] rt_spin_lock+0xc2/0x400 kernel/locking/spinlock_rt.c:57 spin_lock include/linux/spinlock_rt.h:45 [inline] ip_vs_conn_unlink net/netfilter/ipvs/ip_vs_conn.c:324 [inline] ip_vs_conn_expire+0xd4a/0x2390 net/netfilter/ipvs/ip_vs_conn.c:1260 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> Reported-by: syzbot+504e778ddaecd36fdd17@syzkaller.appspotmail.com Link: https://sashiko.dev/#/patchset/20260415200216.79699-1-ja%40ssi.bg Link: https://sashiko.dev/#/patchset/20260420165539.85174-4-ja%40ssi.bg Link: https://sashiko.dev/#/patchset/20260422135823.50489-4-ja%40ssi.bg Fixes: 2fa7cc9c7025 ("ipvs: switch to per-net connection table") Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-05ipvs: fix races around the conn_lfactor and svc_lfactor sysctl varsJulian Anastasov2-4/+10
Sashiko warns that the new sysctls vars can be changed after the hash tables are destroyed and their respective resizing works canceled, leading to mod_delayed_work() being called for canceled works. Solve this in different ways. conn_tab can be present even without services and is destroyed only on netns exit, so use disable_delayed_work_sync() to disable the work instead of adding more synchronization mechanisms. As for the svc_table, it is destroyed when the services are deleted, so we must be sure that netns exit is not called yet (the check for 'enable') and the work is not canceled by checking all under same mutex lock. Also, use WRITE_ONCE when updating the sysctl vars as we already read them with READ_ONCE. Link: https://sashiko.dev/#/patchset/20260410112352.23599-1-fw%40strlen.de Fixes: 8d7de5477e47 ("ipvs: add conn_lfactor and svc_lfactor sysctl vars") Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-05ipvs: fixes for the new ip_vs_status infoJulian Anastasov1-15/+36
Sashiko reports some problems for the recently added /proc/net/ip_vs_status: * ip_vs_status_show() as a table reader may run long after the conn_tab and svc_table table are released. While ip_vs_conn_flush() properly changes the conn_tab_changes counter when conn_tab is removed, ip_vs_del_service() and ip_vs_flush() were missing such change for the svc_table_changes counter. As result, readers like ip_vs_dst_event() and ip_vs_status_show() may continue to use a freed table after a cond_resched_rcu() call. * While counting the buckets in ip_vs_status_show() make sure we traverse only the needed number of entries in the chain. This also prevents possible overflow of the 'count' variable. * Add check for 'loops' to prevent infinite loops while restarting the traversal on table change. * While IP_VS_CONN_TAB_MAX_BITS is 20 on 32-bit platforms and there is no risk to overflow when multiplying the number of conn_tab buckets to 100, prefer the div_u64() helper to make the following dividing safer. * Use 0440 permissions for ip_vs_status to restrict the info only to root due to the exported information for hash distribution. Link: https://sashiko.dev/#/patchset/20260410112352.23599-1-fw%40strlen.de Fixes: 9a9ccef907a7 ("ipvs: add ip_vs_status info") Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-01netfilter: flowtable: use skb_pull_rcsum() to pop vlan/pppoe headerPablo Neira Ayuso1-2/+2
This adjusts the checksum, if required, after pulling the layer 2 header, either the pppoe header or the inner vlan header in the double-tagged vlan packets. Fixes: 4cd91f7c290f ("netfilter: flowtable: add vlan support") Fixes: 72efd585f714 ("netfilter: flowtable: add pppoe support") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-01netfilter: flowtable: fix inline pppoe encapsulation in xmit pathPablo Neira Ayuso3-4/+46
Address two issues in the inline pppoe encapsulation: - Add needs_gso_segment flag to segment PPPoE packets in software given that there is no GSO support for this. - Use FLOW_OFFLOAD_XMIT_DIRECT since neighbour cache is not available in point-to-point device, use the hardware address that is obtained via flowtable path discovery (ie. fill_forward_path). Fixes: 18d27bed0880 ("netfilter: flowtable: inline pppoe encapsulation in xmit path") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-01netfilter: flowtable: fix inline vlan encapsulation in xmit pathPablo Neira Ayuso1-37/+73
Several issues in the inline vlan support: - The layer 2 encapsulation representation in the tuple takes encap[0] as the outer header and encap[1] as the inner header as seen from the ingress path. Reverse the encap loop to push first the inner then the outer vlan header. - Postpone pushing the layer 2 header once destination device is known. This allows to calculate the needed hearoom via LL_RESERVED_SPACE to accommodate the layer 2 headers. - Add and use nf_flow_vlan_push() as suggested by Eric Woudstra, this is a simplified version of skb_vlan_push() for egress path only. Fixes: c653d5a78f34 ("netfilter: flowtable: inline vlan encapsulation in xmit path") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: flowtable: ensure sufficient headroom in xmit pathPablo Neira Ayuso1-2/+11
Check for headroom and call skb_expand_head() like in the IP output path to ensure there is sufficient headroom for the mac header when forwarding this packet as suggested by sashiko. Fixes: b5964aac51e0 ("netfilter: flowtable: consolidate xmit path") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: xtables: fix L4 header parsing for non-first fragmentsFernando Fernandez Mancera5-3/+23
Multiple targets and matches relies on L4 header to operate. For fragmented packets, every fragment carries the transport protocol identifier, but only the first fragment contains the L4 header. As the 'raw' table can be configured to run at priority -450 (before defragmentation at -400), the target/match can be reached before reassembly. In this case, non-first fragments have their payload incorrectly parsed as a TCP/UDP header. This would be of course a misconfiguration scenario. In most of the cases this just lead to a unreliable behavior for fragmented traffic. Add a fragment check to ensure target/match only evaluates unfragmented packets or the first fragment in the stream. Fixes: 902d6a4c2a4f ("netfilter: nf_defrag: Skip defrag if NOTRACK is set") Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: nf_tables: skip L4 header parsing for non-first fragmentsFernando Fernandez Mancera4-7/+7
The tproxy, osf and exthdr (SCTP) expressions rely on the presence of transport layer headers to perform socket lookups, fingerprint matching, or chunk extraction. For fragmented packets, while the IP protocol remains constant across all fragments, only the first fragment contains the actual L4 header. The expressions could be attached to a chain with a priority lower than -400, bypassing defragmentation. Or could be used in stateless environments where defragmentation is not happening at all. This could result in garbage data being used for the matching. Add a check for pkt->fragoff so only unfragmented packets or the first fragment is processed. Fixes: 133dc203d77d ("netfilter: nft_exthdr: Support SCTP chunks") Fixes: 4ed8eb6570a4 ("netfilter: nf_tables: Add native tproxy support") Fixes: b96af92d6eaf ("netfilter: nf_tables: implement Passive OS fingerprint module in nft_osf") Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: nf_tables: fix netdev hook allocation memleak with dormant tablesFlorian Westphal1-14/+20
sashiko says: could the related code in __nf_tables_abort() leak the struct nft_hook objects when the table is dormant? In __nf_tables_abort(), when rolling back a NEWCHAIN transaction that updates hooks, the code conditionally unregisters and frees the hooks only if the table is not dormant [..] if (!(table->flags & NFT_TABLE_F_DORMANT)) { nft_netdev_unregister_hooks(net, &nft_trans_chain_hooks(trans), true); } ... nft_trans_destroy(trans); Unfortunately netdev family mixes hook registration and allocation. Push table struct down and only check for the flag to unregister. Fixes: 216e7bf7402c ("netfilter: nf_tables: skip netdev hook unregistration if table is dormant") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: xt_CT: fix usersize for v1 and v2 revisionFlorian Westphal1-4/+4
While resurrecting the conntrack-tool test cases I found following bug: In: iptables -I OUTPUT -t raw -p 13 -j CT --timeout test-generic Out: [0:0] -A OUTPUT -p 13 -j CT --timeout test Data after first four bytes of the timeout policy name is never copied to userspace because its treated as kernel-only. Fixes: ec2318904965 ("xtables: extend matches and targets with .usersize") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: nft_compat: run xt_check_hooks_{match,target}() from .validatePablo Neira Ayuso2-10/+36
Several matches and one target check that the hook is correct from checkentry(), however, the basechain is only available from nft_table_validate(). This patch uses xt_check_hooks_{match,target}() from the nft_compat expression .validate path. This patch sets the table in the nft_ctx struct in nft_table_validate() which is required by this patch. Based on patch from Florian Westphal. Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables") Reported-by: Xiang Mei <xmei5@asu.edu> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: x_tables: add .check_hooks to matches and targetsPablo Neira Ayuso7-59/+179
Add a new .check_hooks interface for checking if the match/target is used from the validate hook according to its configuration. Move existing conditional hook check based on the match/target configuration from .checkentry to .check_hooks for the following matches/targets: - addrtype - devgroup - physdev - policy - set - TCPMSS - SET This is a preparation patch to fix nft_compat, not functional changes are intended. Based on patch from Florian Westphal. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: nft_fwd_netdev: use recursion counter in neigh egress pathWeiming Shi2-16/+8
nft_fwd_neigh can be used in egress chains (NF_NETDEV_EGRESS). When the forwarding rule targets the same device or two devices forward to each other, neigh_xmit() triggers dev_queue_xmit() which re-enters nf_hook_egress(), causing infinite recursion and stack overflow. Move the nf_get_nf_dup_skb_recursion() accessor and NF_RECURSION_LIMIT to the shared header nf_dup_netdev.h as a static inline, so that nft_fwd_netdev can use the recursion counter directly without exported function call overhead. Guard neigh_xmit() with the same recursion limit already used in nf_do_netdev_egress(). [ Updated to cache the nf_get_nf_dup_skb_recursion pointer. --pablo ] Fixes: f87b9464d152 ("netfilter: nft_fwd_netdev: Support egress hook") Reported-by: Xiang Mei <xmei5@asu.edu> Signed-off-by: Weiming Shi <bestswngs@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: nft_fwd_netdev: add device and headroom validate with neigh forwardingPablo Neira Ayuso1-2/+14
The ttl field has been decremented already and evaluation of this rule would proceed, just drop this packet instead if there is no destination device to forwards this packet. This is exactly what nf_dup already does in this case. Moreover, check for headroom and call skb_expand_head() like in the IP output path to ensure there is sufficient headroom when forwarding this via neigh_xmit(). Fixes: d32de98ea70f ("netfilter: nft_fwd_netdev: allow to forward packets via neighbour layer") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-30netfilter: replace skb_try_make_writable() by skb_ensure_writable()Pablo Neira Ayuso2-4/+5
skb_try_make_writable() only works on clones and uncloned packets might have their network header in paged fragments. nft_fwd needs to work for the ingress and egress hooks, but the egress hook where skb->data points to the mac header, use skb_network_offset() to include the mac header. The flowtable is fine since it already uses the transport offset. Fixes: d32de98ea70f ("netfilter: nft_fwd_netdev: allow to forward packets via neighbour layer") Fixes: 7d2086871762 ("netfilter: nf_flow_table: move ipv4 offload hook code to nf_flow_table") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-28netfilter: skip recording stale or retransmitted INITXin Long1-3/+7
An INIT whose init_tag matches the peer's vtag does not provide new state information. It indicates either: - a stale INIT (after INIT-ACK has already been seen on the same side), or - a retransmitted INIT (after INIT has already been recorded on the same side). In both cases, the INIT must not update ct->proto.sctp.init[] state, since it does not advance the handshake tracking and may otherwise corrupt INIT/INIT-ACK validation logic. Allow INIT processing only when the conntrack entry is newly created (SCTP_CONNTRACK_NONE), or when the init_tag differs from the stored peer vtag. Note it skips the check for the ct with old_state SCTP_CONNTRACK_NONE in nf_conntrack_sctp_packet(), as it is just created in sctp_new() where it set ct->proto.sctp.vtag[IP_CT_DIR_REPLY] = ih->init_tag. Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.") Signed-off-by: Xin Long <lucien.xin@gmail.com> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Acked-by: Florian Westphal <fw@strlen.de> Link: https://patch.msgid.link/ee56c3e416452b2a40589a2a85245ac2ad5e9f4b.1777214801.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-24netfilter: nf_conntrack_sip: don't use simple_strtoulFlorian Westphal2-34/+119
Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(), and ct_sip_parse_request() with a new sip_parse_port() helper that validates each digit against the buffer limit, eliminating the use of simple_strtoul() which assumes NUL-terminated strings. The previous code dereferenced pointers without bounds checks after sip_parse_addr() and relied on simple_strtoul() on non-NUL-terminated skb data. A port that reaches the buffer limit without a trailing character is also rejected as malformed. Also get rid of all simple_strtoul() usage in conntrack, prefer a stricter version instead. There are intentional changes: - Bail out if number is > UINT_MAX and indicate a failure, same for too long sequences. While we do accept 05535 as port 5535, we will not accept e.g. 'sip:10.0.0.1:005060'. While its syntactically valid under RFC 3261, we should restrict this to not waste cycles when presented with malformed packets with 64k '0' characters. - Force base 10 in ct_sip_parse_numerical_param(). This is used to fetch 'expire=' and 'rports='; both are expected to use base-10. - In nf_nat_sip.c, only accept the parsed value if its within the 1k-64k range. - epaddr_len now returns 0 if the port is invalid, as it already does for invalid ip addresses. This is intentional. nf_conntrack_sip performs lots of guesswork to find the right parts of the message to parse. Being stricter could break existing setups. Connection tracking helpers are designed to allow traffic to pass, not to block it. Based on an earlier patch from Jenny Guanni Qu <qguanni@gmail.com>. Fixes: 05e3ced297fe ("[NETFILTER]: nf_conntrack_sip: introduce SIP-URI parsing helper") Reported-by: Klaudia Kloc <klaudia@vidocsecurity.com> Reported-by: Dawid Moczadło <dawid@vidocsecurity.com> Reported-by: Jenny Guanni Qu <qguanni@gmail.com>. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-24netfilter: reject zero shift in nft_bitwiseKai Ma1-1/+2
Reject zero shift operands for nft_bitwise left and right shift expressions during initialization. The carry propagation logic computes the carry from the adjacent 32-bit word using BITS_PER_TYPE(u32) - shift. A zero shift operand turns this into a 32-bit shift, which is undefined behaviour. Reject zero shift operands in the control plane, alongside the existing check for values greater than or equal to 32, so malformed rules never reach the packet path. Fixes: 567d746b55bc ("netfilter: bitwise: add support for shifts.") Cc: stable@kernel.org Reported-by: Yuan Tan <yuantan098@gmail.com> Reported-by: Yifan Wu <yifanwucs@gmail.com> Reported-by: Juefei Pu <tomapufckgml@gmail.com> Reported-by: Xin Liu <bird@lzu.edu.cn> Signed-off-by: Kai Ma <k4729.23098@gmail.com> Signed-off-by: Ren Wei <n05ec@lzu.edu.cn> Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-24netfilter: xt_policy: fix strict mode inbound policy matchingJiexun Wang1-1/+1
match_policy_in() walks sec_path entries from the last transform to the first one, but strict policy matching needs to consume info->pol[] in the same forward order as the rule layout. Derive the strict-match policy position from the number of transforms already consumed so that multi-element inbound rules are matched consistently. Fixes: c4b885139203 ("[NETFILTER]: x_tables: replace IPv4/IPv6 policy match by address family independant version") Reported-by: Yuan Tan <yuantan098@gmail.com> Reported-by: Yifan Wu <yifanwucs@gmail.com> Reported-by: Juefei Pu <tomapufckgml@gmail.com> Reported-by: Xin Liu <bird@lzu.edu.cn> Signed-off-by: Jiexun Wang <wangjiexun2025@gmail.com> Signed-off-by: Ren Wei <n05ec@lzu.edu.cn> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-21netfilter: nf_tables: add hook transactions for device deletionsPablo Neira Ayuso1-60/+204
Restore the flag that indicates that the hook is going away, ie. NFT_HOOK_REMOVE, but add a new transaction object to track deletion of hooks without altering the basechain/flowtable hook_list during the preparation phase. The existing approach that moves the hook from the basechain/flowtable hook_list to transaction hook_list breaks netlink dump path readers of this RCU-protected list. It should be possible use an array for nft_trans_hook to store the deleted hooks to compact the representation but I am not expecting many hook object, specially now that wildcard support for devices is in place. Note that the nft_trans_chain_hooks() list contains a list of struct nft_trans_hook objects for DELCHAIN and DELFLOWTABLE commands, while this list stores struct nft_hook objects for NEWCHAIN and NEWFLOWTABLE. Note that new commands can be updated to use nft_trans_hook for consistency. This patch also adapts the event notification path to deal with the list of hook transactions. Fixes: 7d937b107108 ("netfilter: nf_tables: support for deleting devices in an existing netdev chain") Fixes: b6d9014a3335 ("netfilter: nf_tables: delete flowtable hooks via transaction list") Reported-by: Xiang Mei <xmei5@asu.edu> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-04-21netfilter: nf_tables: join hook list via splice_list_rcu() in commit phasePablo Neira Ayuso1-4/+4
Publish new hooks in the list into the basechain/flowtable using splice_list_rcu() to ensure netlink dump list traversal via rcu is safe while concurrent ruleset update is going on. Fixes: 78d9f48f7f44 ("netfilter: nf_tables: add devices to existing flowtable") Fixes: b9703ed44ffb ("netfilter: nf_tables: support for adding new devices to an existing netdev chain") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>