Commit cdec942a authored by Eric Dumazet's avatar Eric Dumazet Committed by Florian Westphal
Browse files

netfilter: xt_owner: no longer acquire sk_callback_lock in mt_owner() 



After commit 983512f3 ("net: Drop the lock in skb_may_tx_timestamp()")
from Sebastian Andrzej Siewior, apply the same logic in mt_owner()
to avoid touching sk_callback_lock.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
parent 5663ac3e

net/netfilter/xt_owner.c

+14 −14
Original line number Diff line number Diff line
@@ -63,11 +63,12 @@ static bool 
owner_mt(const struct sk_buff *skb, struct xt_action_param *par)

{

	const struct xt_owner_match_info *info = par->matchinfo;

	const struct file *filp;

	struct sock *sk = skb_to_full_sk(skb);

	struct net *net = xt_net(par);

	const struct socket *sock;

	const struct file *filp;



	if (!sk || !sk->sk_socket || !net_eq(net, sock_net(sk)))

	if (!sk || !READ_ONCE(sk->sk_socket) || !net_eq(net, sock_net(sk)))

		return (info->match ^ info->invert) == 0;

	else if (info->match & info->invert & XT_OWNER_SOCKET)

		/*
@@ -76,24 +77,26 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par) 
		 */

		return false;



	read_lock_bh(&sk->sk_callback_lock);

	filp = sk->sk_socket ? sk->sk_socket->file : NULL;

	if (filp == NULL) {

		read_unlock_bh(&sk->sk_callback_lock);

	/* 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);

	filp = sock ? READ_ONCE(sock->file) : NULL;

	if (filp == NULL)

		return ((info->match ^ info->invert) &

		       (XT_OWNER_UID | XT_OWNER_GID)) == 0;

	}



	if (info->match & XT_OWNER_UID) {

		kuid_t uid_min = make_kuid(net->user_ns, info->uid_min);

		kuid_t uid_max = make_kuid(net->user_ns, info->uid_max);



		if ((uid_gte(filp->f_cred->fsuid, uid_min) &&

		     uid_lte(filp->f_cred->fsuid, uid_max)) ^

		    !(info->invert & XT_OWNER_UID)) {

			read_unlock_bh(&sk->sk_callback_lock);

		    !(info->invert & XT_OWNER_UID))

			return false;

	}

	}



	if (info->match & XT_OWNER_GID) {

		unsigned int i, match = false;
@@ -117,13 +120,10 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par) 
			}

		}



		if (match ^ !(info->invert & XT_OWNER_GID)) {

			read_unlock_bh(&sk->sk_callback_lock);

		if (match ^ !(info->invert & XT_OWNER_GID))

			return false;

	}

	}



	read_unlock_bh(&sk->sk_callback_lock);

	return true;

}