From b62eb8dcf2c47d4d676a434efbd57c4f776f7829 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Wed, 6 May 2026 12:07:14 +0200 Subject: netfilter: x_tables: allocate hook ops while under mutex 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 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/x_tables.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index a81b46af5118..cb4b694dd9e4 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -305,6 +305,7 @@ struct xt_counters *xt_counters_alloc(unsigned int counters); struct xt_table *xt_register_table(struct net *net, const struct xt_table *table, + const struct nf_hook_ops *template_ops, struct xt_table_info *bootstrap, struct xt_table_info *newinfo); void *xt_unregister_table(struct xt_table *table); -- cgit v1.2.3 From 527d6931473b75d90e38942aae6537d1a527f1fd Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Wed, 6 May 2026 12:07:15 +0200 Subject: netfilter: x_tables: add and use xt_unregister_table_pre_exit 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 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/x_tables.h | 1 + include/linux/netfilter_arp/arp_tables.h | 1 - include/linux/netfilter_ipv4/ip_tables.h | 1 - include/linux/netfilter_ipv6/ip6_tables.h | 1 - 4 files changed, 1 insertion(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index cb4b694dd9e4..74486714ae20 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -309,6 +309,7 @@ struct xt_table *xt_register_table(struct net *net, struct xt_table_info *bootstrap, struct xt_table_info *newinfo); void *xt_unregister_table(struct xt_table *table); +void xt_unregister_table_pre_exit(struct net *net, u8 af, const char *name); struct xt_table_info *xt_replace_table(struct xt_table *table, unsigned int num_counters, diff --git a/include/linux/netfilter_arp/arp_tables.h b/include/linux/netfilter_arp/arp_tables.h index a40aaf645fa4..05631a25e622 100644 --- a/include/linux/netfilter_arp/arp_tables.h +++ b/include/linux/netfilter_arp/arp_tables.h @@ -53,7 +53,6 @@ int arpt_register_table(struct net *net, const struct xt_table *table, const struct arpt_replace *repl, const struct nf_hook_ops *ops); void arpt_unregister_table(struct net *net, const char *name); -void arpt_unregister_table_pre_exit(struct net *net, const char *name); extern unsigned int arpt_do_table(void *priv, struct sk_buff *skb, const struct nf_hook_state *state); diff --git a/include/linux/netfilter_ipv4/ip_tables.h b/include/linux/netfilter_ipv4/ip_tables.h index 132b0e4a6d4d..13593391d605 100644 --- a/include/linux/netfilter_ipv4/ip_tables.h +++ b/include/linux/netfilter_ipv4/ip_tables.h @@ -26,7 +26,6 @@ int ipt_register_table(struct net *net, const struct xt_table *table, const struct ipt_replace *repl, const struct nf_hook_ops *ops); -void ipt_unregister_table_pre_exit(struct net *net, const char *name); void ipt_unregister_table_exit(struct net *net, const char *name); /* Standard entry. */ diff --git a/include/linux/netfilter_ipv6/ip6_tables.h b/include/linux/netfilter_ipv6/ip6_tables.h index 8b8885a73c76..c6d5b927830d 100644 --- a/include/linux/netfilter_ipv6/ip6_tables.h +++ b/include/linux/netfilter_ipv6/ip6_tables.h @@ -27,7 +27,6 @@ extern void *ip6t_alloc_initial_table(const struct xt_table *); int ip6t_register_table(struct net *net, const struct xt_table *table, const struct ip6t_replace *repl, const struct nf_hook_ops *ops); -void ip6t_unregister_table_pre_exit(struct net *net, const char *name); void ip6t_unregister_table_exit(struct net *net, const char *name); extern unsigned int ip6t_do_table(void *priv, struct sk_buff *skb, const struct nf_hook_state *state); -- cgit v1.2.3 From b4597d5fd7d2f8cebfffd40dffb5e003cc78964c Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Wed, 6 May 2026 12:07:17 +0200 Subject: netfilter: x_tables: add and use xtables_unregister_table_exit 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 --- include/linux/netfilter/x_tables.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 74486714ae20..5a1c5c336fa4 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -308,8 +308,8 @@ struct xt_table *xt_register_table(struct net *net, const struct nf_hook_ops *template_ops, struct xt_table_info *bootstrap, struct xt_table_info *newinfo); -void *xt_unregister_table(struct xt_table *table); void xt_unregister_table_pre_exit(struct net *net, u8 af, const char *name); +struct xt_table *xt_unregister_table_exit(struct net *net, u8 af, const char *name); struct xt_table_info *xt_replace_table(struct xt_table *table, unsigned int num_counters, -- cgit v1.2.3 From dcb0f9aefdd604d36710fda53c25bd7cf4a3e37a Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 7 May 2026 13:00:28 +0200 Subject: netfilter: nf_conntrack_expect: restore helper propagation via expectation 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 Tested-by: Ilya Maximets Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_conntrack_expect.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/netfilter/nf_conntrack_expect.h b/include/net/netfilter/nf_conntrack_expect.h index e9a8350e7ccf..80f50fd0f7ad 100644 --- a/include/net/netfilter/nf_conntrack_expect.h +++ b/include/net/netfilter/nf_conntrack_expect.h @@ -45,9 +45,12 @@ struct nf_conntrack_expect { void (*expectfn)(struct nf_conn *new, struct nf_conntrack_expect *this); - /* Helper to assign to new connection */ + /* Helper that created this expectation */ struct nf_conntrack_helper __rcu *helper; + /* Helper to assign to new connection */ + struct nf_conntrack_helper __rcu *assign_helper; + /* The conntrack of the master connection */ struct nf_conn *master; -- cgit v1.2.3 From e68eadffb724b36ffd3d5619e0efcaf29ec2a175 Mon Sep 17 00:00:00 2001 From: Maoyi Xie Date: Wed, 6 May 2026 16:24:16 +0800 Subject: ipv6: flowlabel: enforce per-netns limit for unprivileged callers fl_size, fl_ht and ip6_fl_lock in net/ipv6/ip6_flowlabel.c are file scope and shared across netns. mem_check() reads fl_size to decide whether to deny non-CAP_NET_ADMIN callers. capable() runs against init_user_ns, so an unprivileged user in any non-init userns can push fl_size past FL_MAX_SIZE - FL_MAX_SIZE / 4 and starve every other unprivileged userns on the host. Add struct netns_ipv6::flowlabel_count, bumped and decremented next to fl_size in fl_intern, ip6_fl_gc and ip6_fl_purge. The new field fills the existing 4-byte hole after ipmr_seq, so struct netns_ipv6 stays the same size on 64-bit builds. Bump FL_MAX_SIZE from 4096 to 8192. It has been 4096 since the file was added. Machines and connection counts have grown. mem_check() folds an extra per-netns ceiling into the existing non-CAP_NET_ADMIN conditional. The ceiling is half of the total budget that unprivileged callers have ever been able to use, i.e. (FL_MAX_SIZE - FL_MAX_SIZE / 4) / 2 = 3072 entries. With FL_MAX_SIZE doubled, this preserves the original per-user reach of 3K (what an unprivileged caller could already obtain before this change), while forcing an attacker to spread allocations across at least two netns to exhaust the global non-CAP_NET_ADMIN budget. CAP_NET_ADMIN against init_user_ns still bypasses both caps. The previous patch took ip6_fl_lock across mem_check and fl_intern, so the new flowlabel_count read in mem_check and the new flowlabel_count++ in fl_intern run under the same critical section. flowlabel_count is therefore plain int, like fl_size. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Suggested-by: Willem de Bruijn Reviewed-by: Willem de Bruijn Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Maoyi Xie Link: https://patch.msgid.link/20260506082416.2259567-3-maoyixie.tju@gmail.com Signed-off-by: Jakub Kicinski --- include/net/netns/ipv6.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h index 499e4288170f..875916d60bfe 100644 --- a/include/net/netns/ipv6.h +++ b/include/net/netns/ipv6.h @@ -119,6 +119,7 @@ struct netns_ipv6 { struct fib_notifier_ops *notifier_ops; struct fib_notifier_ops *ip6mr_notifier_ops; atomic_t ipmr_seq; + int flowlabel_count; struct { struct hlist_head head; spinlock_t lock; -- cgit v1.2.3 From f2ab4fd02777c4081be38c35f939e4dc529b8952 Mon Sep 17 00:00:00 2001 From: Ilya Maximets Date: Thu, 7 May 2026 14:04:26 +0200 Subject: net: nsh: fix incorrect header length macros NSH header length is a 6-bit field that encodes the total length of the header in 4-byte words. So the maximum length is 0b111111 * 4, which is 252 and not 256. The maximum context length is the same number minus the length of the base header (8), so 244. These macros are used to validate push_nsh() action in openvswitch. Miscalculation here doesn't cause any real issues. In the worst case the oversized context is truncated while building the header, so we'll construct and send a broken packet, which is not a big problem, as any receiver should validate the fields. No invalid memory accesses will happen during the header push. But we should fix the macros to reject the incorrect actions in the first place. Using previously defined values and calculating the length instead of defining numbers directly, so it's easier to understand where they come from and harder to make a mistake. Fixes: 1f0b7744c505 ("net: add NSH header structures and helpers") Signed-off-by: Ilya Maximets Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20260507120434.2962505-1-i.maximets@ovn.org Signed-off-by: Jakub Kicinski --- include/net/nsh.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/net/nsh.h b/include/net/nsh.h index 16a751093896..15a26c590815 100644 --- a/include/net/nsh.h +++ b/include/net/nsh.h @@ -247,10 +247,10 @@ struct nshhdr { #define NSH_M_TYPE1_LEN 24 /* NSH header maximum Length. */ -#define NSH_HDR_MAX_LEN 256 +#define NSH_HDR_MAX_LEN ((NSH_LEN_MASK >> NSH_LEN_SHIFT) * 4) /* NSH context headers maximum Length. */ -#define NSH_CTX_HDRS_MAX_LEN 248 +#define NSH_CTX_HDRS_MAX_LEN (NSH_HDR_MAX_LEN - NSH_BASE_HDR_LEN) static inline struct nshhdr *nsh_hdr(struct sk_buff *skb) { -- cgit v1.2.3 From efda25ee84325385f859d10872590e90ce837243 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Wed, 6 May 2026 20:07:13 +0000 Subject: genetlink: free the skb on 'group >= family->n_mcgrps' These methods generally consume ownership of the provided skb, so even if an error path is encountered, the skb is freed. This is because the very first thing they do after some initial setup is to unconditionally consume the skb via consume_skb(skb). Any subsequent errors lead to the core netlink layer freeing the skb. However, there is one check that occurs before ownership is passed, which is the check for the group index. So if this error condition is encountered, then the skb is leaked. This error condition is generally considered a violation of the netlink API, so it's not expected to occur under normal circumstances. For the same reason, no callers check for this error condition, and no callers need to be adjusted. However, we should still follow the same ownership semantics of the rest of the function. Thus, free the skb in this codepath. Suggested-by: Andrew Lunn Suggested-by: Matthew Maurer Fixes: 2a94fe48f32c ("genetlink: make multicast groups const, prevent abuse") Link: https://lore.kernel.org/r/845b36ba-7b3a-41f2-acb2-b284f253e2ca@lunn.ch Signed-off-by: Alice Ryhl Link: https://patch.msgid.link/20260506-genlmsg-return-v2-1-a63ee2a055d6@google.com Signed-off-by: Jakub Kicinski --- include/net/genetlink.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/genetlink.h b/include/net/genetlink.h index 7b84f2cef8b1..d70510ac31ab 100644 --- a/include/net/genetlink.h +++ b/include/net/genetlink.h @@ -489,8 +489,10 @@ genlmsg_multicast_netns_filtered(const struct genl_family *family, netlink_filter_fn filter, void *filter_data) { - if (WARN_ON_ONCE(group >= family->n_mcgrps)) + if (WARN_ON_ONCE(group >= family->n_mcgrps)) { + nlmsg_free(skb); return -EINVAL; + } group = family->mcgrp_offset + group; return nlmsg_multicast_filtered(net->genl_sock, skb, portid, group, flags, filter, filter_data); -- cgit v1.2.3 From 6624bba469a325ecd699feae400b77cd11c76b98 Mon Sep 17 00:00:00 2001 From: Jinliang Zheng Date: Mon, 11 May 2026 23:30:59 +0800 Subject: macsec: use rcu_work to defer RX SA crypto cleanup out of softirq crypto_free_aead() can internally invoke vunmap() (e.g. via dma_free_attrs() in hardware crypto drivers such as hisi_sec2). vunmap() must not be called from softirq context, but free_rxsa() is an RCU callback that runs in softirq, leading to a kernel crash: vunmap+0x4c/0x70 __iommu_dma_free+0xd0/0x138 dma_free_attrs+0xf4/0x100 sec_aead_exit+0x64/0xb8 [hisi_sec2] crypto_destroy_tfm+0x98/0x110 free_rxsa+0x28/0x50 [macsec] rcu_do_batch+0x184/0x460 rcu_core+0xf4/0x1f8 handle_softirqs+0x118/0x330 Use rcu_work to defer the cleanup to a workqueue. rcu_work dispatches the worker asynchronously after the RCU grace period, so no thread blocks waiting, and concurrent releases of multiple SAs naturally share the same grace period. Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver") Signed-off-by: Jinliang Zheng Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20260511153102.2640368-3-alexjlzheng@tencent.com Signed-off-by: Jakub Kicinski --- include/net/macsec.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/macsec.h b/include/net/macsec.h index bc7de5b53e54..0980ef36fbf0 100644 --- a/include/net/macsec.h +++ b/include/net/macsec.h @@ -9,6 +9,7 @@ #include #include +#include #include #include @@ -123,6 +124,7 @@ struct macsec_dev_stats { * @key: key structure * @ssci: short secure channel identifier * @stats: per-SA stats + * @destroy_work: deferred work to free the SA in process context after RCU grace period */ struct macsec_rx_sa { struct macsec_key key; @@ -136,7 +138,7 @@ struct macsec_rx_sa { bool active; struct macsec_rx_sa_stats __percpu *stats; struct macsec_rx_sc *sc; - struct rcu_head rcu; + struct rcu_work destroy_work; }; struct pcpu_rx_sc_stats { -- cgit v1.2.3 From 552cc2306c3d87632f44a655737d1d367c2a3295 Mon Sep 17 00:00:00 2001 From: Jinliang Zheng Date: Mon, 11 May 2026 23:31:00 +0800 Subject: macsec: use rcu_work to defer TX SA crypto cleanup out of softirq free_txsa() is an RCU callback running in softirq context, but calls crypto_free_aead() which can invoke vunmap() internally on hardware crypto drivers (e.g. hisi_sec2), triggering a kernel crash. Use rcu_work to defer the cleanup to a workqueue, for the same reasons as the analogous fix to free_rxsa() in the previous patch. Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver") Signed-off-by: Jinliang Zheng Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20260511153102.2640368-4-alexjlzheng@tencent.com Signed-off-by: Jakub Kicinski --- include/net/macsec.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/macsec.h b/include/net/macsec.h index 0980ef36fbf0..d962093ee923 100644 --- a/include/net/macsec.h +++ b/include/net/macsec.h @@ -176,6 +176,7 @@ struct macsec_rx_sc { * @key: key structure * @ssci: short secure channel identifier * @stats: per-SA stats + * @destroy_work: deferred work to free the SA in process context after RCU grace period */ struct macsec_tx_sa { struct macsec_key key; @@ -188,7 +189,7 @@ struct macsec_tx_sa { refcount_t refcnt; bool active; struct macsec_tx_sa_stats __percpu *stats; - struct rcu_head rcu; + struct rcu_work destroy_work; }; /** -- cgit v1.2.3