Kyle Zeng f88bb3606e netlink: avoid hashing the network namespace pointer ... The netlink rhashtable key includes a raw struct net pointer and a user-controlled port ID. Both /proc/net/netlink and socket diagnostics expose the table's bucket order. By binding and rebinding chosen NETLINK_USERSOCK port IDs, an unprivileged reader can distinguish equal buckets and recover the low bits of the Jenkins hash. Its 32-bit seed and the limited set of kernel-image slides can then be searched offline to recover the address of init_net. Use the namespace's unique, non-address net_cookie in the comparison key instead. It is assigned before the per-net initializers run and remains unchanged for the namespace's lifetime. The lookup key and object hash are still built by netlink_compare_arg_init(), keeping lookup, insertion, removal and rehashing consistent while preserving namespace separation. Neither public table walker needs to change. Reading the socket's namespace cookie in netlink_compare() is safe under RCU, including during namespace teardown. netlink_release() removes the socket from the hash table and defers its final put with call_rcu(). cleanup_net() runs the per-net exit methods and waits for outstanding RCU callbacks with rcu_barrier() before freeing namespace storage. Unlike ns.ns_id, net_cookie is also available and initialized during setup_net() in older stable kernels, making the change straightforward to backport to v5.15 and later. Fixes: c428ecd1a2 ("netlink: Move namespace into hash key") Assisted-by: LLM Signed-off-by: Kyle Zeng <kylebot@openai.com> Reviewed-by: Simon Horman <horms@kernel.org> Reviewed-by: Eric Dumazet <edumazet@kernel.org> Link: https://patch.msgid.link/20261008011359.63727-2-kylebot@openai.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>		2026-10-15 10:27:45 +02:00
..
af_netlink.c	netlink: avoid hashing the network namespace pointer	2026-10-15 10:27:45 +02:00
af_netlink.h	netlink: terminate outstanding dump on socket close	2024-11-07 13:45:34 -08:00
diag.c	netlink: do not free nlk->groups while lockless readers can use it	2026-09-15 18:44:02 -07:00
genetlink.c	genetlink: report the real command id for dump-only ops in policy dumps	2026-09-22 15:21:32 +02:00
genetlink.h	netlink: create a new header for internal genetlink symbols	2024-04-01 21:44:34 -07:00
Kconfig
Makefile
policy.c	genetlink: use maxattr of 0 for the reject policy	2026-03-12 18:02:13 -07:00