[PATCH nf-next] netfilter: nfnetlink_log: no longer acquire sk_callback_lock
From: Eric Dumazet <edumazet@google.com>
Date: 2026-02-26 08:58:19
Also in:
netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
After commit 983512f3a87f ("net: Drop the lock in skb_may_tx_timestamp()")
from Sebastian Andrzej Siewior, apply the same logic in
__build_packet_message() to avoid touching sk->sk_callback_lock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
net/netfilter/nfnetlink_log.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index bfcb9cd335bff59fa4d0d09eb52943566e4098e7..bef28e5230bb3b4d4b1ef4d5111909bac969b343 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c@@ -611,19 +611,26 @@ __build_packet_message(struct nfnl_log_net *log, /* UID */ sk = skb->sk; if (sk && sk_fullsock(sk)) { - read_lock_bh(&sk->sk_callback_lock); - if (sk->sk_socket && sk->sk_socket->file) { - struct file *file = sk->sk_socket->file; + const struct socket *sock; + const struct file *file; + + /* The sk pointer remains valid as long as the skb is. + * The sk_socket and file pointer may become NULL + * if the socket is closed. + * Both structures (including file->cred) are RCU freed + * which means they can be accessed within a RCU read section. + */ + sock = READ_ONCE(sk->sk_socket); + file = sock ? READ_ONCE(sock->file) : NULL; + if (file) { const struct cred *cred = file->f_cred; struct user_namespace *user_ns = inst->peer_user_ns; __be32 uid = htonl(from_kuid_munged(user_ns, cred->fsuid)); __be32 gid = htonl(from_kgid_munged(user_ns, cred->fsgid)); - read_unlock_bh(&sk->sk_callback_lock); if (nla_put_be32(inst->skb, NFULA_UID, uid) || nla_put_be32(inst->skb, NFULA_GID, gid)) goto nla_put_failure; - } else - read_unlock_bh(&sk->sk_callback_lock); + } } /* local sequence number */
--
2.53.0.414.gf7e9f6c205-goog