kernel/linux.git/net/ipv4/netfilter, branch v7.1.8

netfilter: nf_conntrack_expect: add and use nf_ct_expect_related_pair()

2026-08-09T18:26:25+00:00

[ Upstream commit 4aa63842fc92de1bce59d4709a0d32e718890bb2 ] Add a new function to insert a pair of expectations, this is required by the SIP and H323 NAT helpers. The spinlock is held to check if there is a slot for both expectations, in such case, insert them. This removes the need for nf_ct_unexpect_related() inside the loop to find a pair of consecutive ports, otherwise inserting expectations whose dead flag is already set on can happen. Bump master_help->expecting for the expectation class after checking if the expectation fits in the master expectation list, which is needed for this new _pair() function variant to run the eviction routine including the preallocated slot for the first expectation in the pair. Fixes: b8b09dc2bf35 ("netfilter: nf_conntrack_expect: use conntrack GC to reap expectations") Reported-by: Jaeyeong Lee Link: https://patch.msgid.link/178377968720.33756.12204817361601593230@proton.me/ Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: conntrack: check NULL when retrieving ct extension

2026-07-24T14:20:26+00:00

[ Upstream commit e3cd138e560764299965fba5ec5240281a7faca2 ] nf_ct_ext_find() might return NULL if ct extension is not found. Add also the null checks to: - nfct_help() - nfct_help_data() - nfct_seqadj() - nfct_nat() This is defensive, for safety reasons. nf_ct_ext_find() used to return NULL if the extension is stale for unconfirmed conntracks if the genid validation fails. Skip NULL check in nf_nat_inet_fn() given this is valid to be NULL for non-initialized ct nat extensions. While at it, fetch ct helper area in nf_ct_expect_related_report() only once and pass it on to other ancilliary functions. Replace WARN_ON() by WARN_ON_ONCE() in nf_ct_unlink_expect_report(). Signed-off-by: Pablo Neira Ayuso Stable-dep-of: 979c13114c0b ("netfilter: nf_conntrack_expect: store master_tuple in expectation") Signed-off-by: Sasha Levin

netfilter: nf_conntrack_helper: dynamically allocate struct nf_conntrack_helper

2026-07-24T14:20:26+00:00

[ Upstream commit 6031487d4e273d7e7c8c7deea5061b7a9aaa9db3 ] Adapt all existing helpers to use a modified version of nf_ct_helper_init(), to dynamically allocate struct nf_conntrack_helper. Allocate expect_policy[] built-in into the helper to ensure this area is reachable after helper removal since a follow up patch adds refcount to track use of the nf_conntrack_helper structure from packet path so it remains around until last reference from ct helper extension is dropped. Export __nf_conntrack_helper_register() which allows to register nfnetlink_cthelper dynamically allocated helper. Adapt nfnetlink_cthelper to use the built-in expect_policy[]. This is a preparation patch to add packet path refcounting to helpers. Signed-off-by: Pablo Neira Ayuso Stable-dep-of: 979c13114c0b ("netfilter: nf_conntrack_expect: store master_tuple in expectation") Signed-off-by: Sasha Levin

netfilter: nf_reject: skip iphdr options when looking for icmp header

2026-07-24T14:20:21+00:00

[ Upstream commit af8d6ae09c0a5f8b8a0d5680203c74b3c1daa85b ] Not a big deal but this hould have used the real ip header length and not the base header size. As-is, if there are options then nf_skb_is_icmp_unreach() result will be random. Fixes: db99b2f2b3e2 ("netfilter: nf_reject: don't reply to icmp error messages") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nft_fib: fix stale stack leak via the OIFNAME register

2026-06-10T16:00:19+00:00

For NFT_FIB_RESULT_OIFNAME the destination register is declared with len = IFNAMSIZ (four 32-bit registers), but on the lookup-fail, RTN_LOCAL and oif-mismatch paths nft_fib{4,6}_eval() only writes one register via "*dest = 0". The remaining three registers are left as whatever was on the stack in nft_do_chain()'s struct nft_regs, and a downstream expression that loads the register span can leak that uninitialised kernel stack to userspace. The NFTA_FIB_F_PRESENT existence check has the same shape: it is only meaningful for NFT_FIB_RESULT_OIF, yet it was accepted for any result type while the eval stores a single byte via nft_reg_store8(), leaving the rest of the declared span stale. Fix both: - replace the bare "*dest = 0" in the eval with nft_fib_store_result(), which strscpy_pad()s the whole IFNAMSIZ for OIFNAME (and is already used on the other early-return path), and - restrict NFTA_FIB_F_PRESENT to NFT_FIB_RESULT_OIF and declare its destination as a single u8, so the marked span matches the one byte the eval writes. Fixes: f6d0cbcf09c5 ("netfilter: nf_tables: add fib expression") Suggested-by: Florian Westphal Cc: stable@vger.kernel.org Signed-off-by: Davide Ornaghi Signed-off-by: Pablo Neira Ayuso

netfilter: x_tables: avoid leaking percpu counter pointers

2026-06-10T15:59:01+00:00

The native and compat get-entries paths copy the fixed rule entry header from the kernelized rule blob to userspace before overwriting the entry's counter fields with a sanitized counter snapshot. On SMP kernels, entry->counters.pcnt contains the percpu allocation address used by x_tables rule counters. A caller can provide a userspace buffer that faults during the initial fixed-header copy after pcnt has been copied but before the later sanitized counter copy runs. The syscall then returns -EFAULT while leaving the raw percpu pointer in userspace. Copy only the fixed entry prefix before counters from the kernelized rule blob, then copy the sanitized counter snapshot into the counter field. Apply this ordering to the IPv4, IPv6, and ARP native and compat get-entries implementations so a fault cannot expose the internal percpu counter pointer. Fixes: 71ae0dff02d7 ("netfilter: xtables: use percpu rule counters") Signed-off-by: Kyle Zeng Signed-off-by: Pablo Neira Ayuso

netfilter: nf_conntrack: destroy stale expectfn expectations on unregister

2026-06-10T15:58:39+00:00

NAT helpers such as nf_nat_h323 store a raw pointer to module text in exp->expectfn (e.g. ip_nat_q931_expect). nf_ct_helper_expectfn_unregister() only unlinks the callback descriptor and never walks the expectation table, so an expectation pending at module removal survives with a dangling exp->expectfn into freed module text. When the expected connection arrives, init_conntrack() invokes exp->expectfn(), now a stale pointer into the unloaded module. Reproduced on a KASAN build by loading the H.323 helpers, creating a Q.931 expectation, unloading nf_nat_h323, then connecting to the expected port: Oops: int3: 0000 [#1] SMP KASAN NOPTI RIP: 0010:0xffffffffa06102d1 init_conntrack.isra.0 (net/netfilter/nf_conntrack_core.c:1862) nf_conntrack_in (net/netfilter/nf_conntrack_core.c:2049) ipv4_conntrack_local (net/netfilter/nf_conntrack_proto.c:223) nf_hook_slow (net/netfilter/core.c:619) __ip_local_out (net/ipv4/ip_output.c:120) __tcp_transmit_skb (net/ipv4/tcp_output.c:1715) tcp_connect (net/ipv4/tcp_output.c:4374) tcp_v4_connect (net/ipv4/tcp_ipv4.c:345) __sys_connect (net/socket.c:2167) Modules linked in: nf_conntrack_h323 [last unloaded: nf_nat_h323] Reaching the dangling state requires CAP_SYS_MODULE in the initial user namespace to remove a NAT helper that still has live expectations, so this is a robustness fix; leaving an expectation pointing at freed text is wrong regardless. Add nf_ct_helper_expectfn_destroy(), which walks the expectation table and drops every expectation whose ->expectfn matches the descriptor being torn down. Call it from each NAT helper's exit path after the existing RCU grace period, so no expectation outlives the code it points at and no extra synchronize_rcu() is introduced. With the fix, the same reproducer runs to completion without the Oops. Fixes: f587de0e2feb ("[NETFILTER]: nf_conntrack/nf_nat: add H.323 helper port") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Weiming Shi Signed-off-by: Pablo Neira Ayuso

netfilter: x_tables: close dangling table module init race

2026-05-07T23:30:17+00:00

Similar to the previous ebtables patch: template add exposes the table to userspace, we must do this last to rnsure the pernet ops are set up (contain the destructors). Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: x_tables: add and use xtables_unregister_table_exit

2026-05-07T23:30:16+00:00

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 Reviewed-by: Tristan Madani Closes: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/ Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: x_tables: unregister the templates first

2026-05-07T23:30:16+00:00

When the module is going away we need to zap the template first. Else there is a small race window where userspace could instantiate a new table after the pernet exit function has removed the current table. Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default") Reported-by: Tristan Madani Reviewed-by: Tristan Madani Closes: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/ Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso