skmsg: Pass psock pointer to ->psock_update_sk_prot()

Using sk_psock() to retrieve psock pointer from sock requires
RCU read lock, but we already get psock pointer before calling
->psock_update_sk_prot() in both cases, so we can just pass it
without bothering sk_psock().

Fixes: 8a59f9d1 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()")
Reported-by: syzbot+320a3bc8d80f478c37e4@syzkaller.appspotmail.com
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+320a3bc8d80f478c37e4@syzkaller.appspotmail.com
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210407032111.33398-1-xiyou.wangcong@gmail.com

include/linux/skmsg.h

@@ -99,7 +99,8 @@ struct sk_psock {
 	void (*saved_close)(struct sock *sk, long timeout);
 	void (*saved_write_space)(struct sock *sk);
 	void (*saved_data_ready)(struct sock *sk);
-	int  (*psock_update_sk_prot)(struct sock *sk, bool restore);
+	int  (*psock_update_sk_prot)(struct sock *sk, struct sk_psock *psock,
+				     bool restore);
 	struct proto			*sk_proto;
 	struct mutex			work_mutex;
 	struct sk_psock_work_state	work_state;
@@ -405,7 +406,7 @@ static inline void sk_psock_restore_proto(struct sock *sk,
 {
 	sk->sk_prot->unhash = psock->saved_unhash;
 	if (psock->psock_update_sk_prot)
-		psock->psock_update_sk_prot(sk, true);
+		psock->psock_update_sk_prot(sk, psock, true);
 }
 
 static inline void sk_psock_set_state(struct sk_psock *psock,

include/net/sock.h

@@ -1114,6 +1114,7 @@ struct inet_hashinfo;
 struct raw_hashinfo;
 struct smc_hashinfo;
 struct module;
+struct sk_psock;
 
 /*
  * caches using SLAB_TYPESAFE_BY_RCU should let .next pointer from nulls nodes
@@ -1185,7 +1186,9 @@ struct proto {
 	void			(*rehash)(struct sock *sk);
 	int			(*get_port)(struct sock *sk, unsigned short snum);
 #ifdef CONFIG_BPF_SYSCALL
-	int			(*psock_update_sk_prot)(struct sock *sk, bool restore);
+	int			(*psock_update_sk_prot)(struct sock *sk,
+							struct sk_psock *psock,
+							bool restore);
 #endif
 
 	/* Keeping track of sockets in use */

include/net/tcp.h

@@ -2215,7 +2215,7 @@ struct sk_psock;
 
 #ifdef CONFIG_BPF_SYSCALL
 struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
-int tcp_bpf_update_proto(struct sock *sk, bool restore);
+int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
 #endif /* CONFIG_BPF_SYSCALL */
 

include/net/udp.h

@@ -543,7 +543,7 @@ static inline void udp_post_segment_fix_csum(struct sk_buff *skb)
 #ifdef CONFIG_BPF_SYSCALL
 struct sk_psock;
 struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
-int udp_bpf_update_proto(struct sock *sk, bool restore);
+int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
 #endif
 
 #endif	/* _UDP_H */

net/core/sock_map.c

@@ -188,7 +188,7 @@ static int sock_map_init_proto(struct sock *sk, struct sk_psock *psock)
 	if (!sk->sk_prot->psock_update_sk_prot)
 		return -EINVAL;
 	psock->psock_update_sk_prot = sk->sk_prot->psock_update_sk_prot;
-	return sk->sk_prot->psock_update_sk_prot(sk, false);
+	return sk->sk_prot->psock_update_sk_prot(sk, psock, false);
 }
 
 static struct sk_psock *sock_map_psock_get_checked(struct sock *sk)

net/ipv4/tcp_bpf.c

@@ -499,9 +499,8 @@ static int tcp_bpf_assert_proto_ops(struct proto *ops)
 	       ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP;
 }
 
-int tcp_bpf_update_proto(struct sock *sk, bool restore)
+int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 {
-	struct sk_psock *psock = sk_psock(sk);
 	int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
 	int config = psock->progs.msg_parser   ? TCP_BPF_TX   : TCP_BPF_BASE;
 

net/ipv4/udp_bpf.c

@@ -103,10 +103,9 @@ static int __init udp_bpf_v4_build_proto(void)
 }
 core_initcall(udp_bpf_v4_build_proto);
 
-int udp_bpf_update_proto(struct sock *sk, bool restore)
+int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 {
 	int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
-	struct sk_psock *psock = sk_psock(sk);
 
 	if (restore) {
 		sk->sk_write_space = psock->saved_write_space;