sock: introduce sk_prot->update_proto()

Currently sockmap calls into each protocol to update the struct proto and replace it. This certainly won't work when the protocol is implemented as a module, for example, AF_UNIX. Introduce a new ops sk->sk_prot->update_proto(), so each protocol can implement its own way to replace the struct proto. Cc: John Fastabend <john.fastabend@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Jakub Sitnicki <jakub@cloudflare.com> Cc: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Cong Wang <cong.wang@bytedance.com>
congwang · Mar 1, 2021 · 55994db · 55994db
1 parent 4a99cd3
commit 55994db
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Showing 12 changed files with 56 additions and 45 deletions.
diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
@@ -98,6 +98,7 @@ 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  (*saved_update_proto)(struct sock *sk, bool restore);
 	struct proto			*sk_proto;
 	struct sk_psock_work_state	work_state;
 	struct work_struct		work;
@@ -350,25 +351,12 @@ static inline void sk_psock_cork_free(struct sk_psock *psock)
 	}
 }
 
-static inline void sk_psock_update_proto(struct sock *sk,
-					 struct sk_psock *psock,
-					 struct proto *ops)
-{
-	/* Pairs with lockless read in sk_clone_lock() */
-	WRITE_ONCE(sk->sk_prot, ops);
-}
-
 static inline void sk_psock_restore_proto(struct sock *sk,
 					  struct sk_psock *psock)
 {
 	sk->sk_prot->unhash = psock->saved_unhash;
-	if (inet_csk_has_ulp(sk)) {
-		tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
-	} else {
-		sk->sk_write_space = psock->saved_write_space;
-		/* Pairs with lockless read in sk_clone_lock() */
-		WRITE_ONCE(sk->sk_prot, psock->sk_proto);
-	}
+	if (psock->saved_update_proto)
+		psock->saved_update_proto(sk, true);
 }
 
 static inline void sk_psock_set_state(struct sk_psock *psock,

diff --git a/include/net/sock.h b/include/net/sock.h
@@ -1184,6 +1184,9 @@ struct proto {
 	void			(*unhash)(struct sock *sk);
 	void			(*rehash)(struct sock *sk);
 	int			(*get_port)(struct sock *sk, unsigned short snum);
+#ifdef CONFIG_BPF_SYSCALL
+	int			(*update_proto)(struct sock *sk, bool restore);
+#endif
 
 	/* Keeping track of sockets in use */
 #ifdef CONFIG_PROC_FS

diff --git a/include/net/tcp.h b/include/net/tcp.h
@@ -2203,6 +2203,7 @@ 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);
 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
 #endif /* CONFIG_BPF_SYSCALL */
 

diff --git a/include/net/udp.h b/include/net/udp.h
@@ -518,6 +518,7 @@ static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
 #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);
 #endif
 
 #endif	/* _UDP_H */
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
@@ -563,11 +563,6 @@ struct sk_psock *sk_psock_init(struct sock *sk, int node)
 
 	write_lock_bh(&sk->sk_callback_lock);
 
-	if (inet_csk_has_ulp(sk)) {
-		psock = ERR_PTR(-EINVAL);
-		goto out;
-	}
-
 	if (sk->sk_user_data) {
 		psock = ERR_PTR(-EBUSY);
 		goto out;

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
@@ -184,26 +184,10 @@ static void sock_map_unref(struct sock *sk, void *link_raw)
 
 static int sock_map_init_proto(struct sock *sk, struct sk_psock *psock)
 {
-	struct proto *prot;
-
-	switch (sk->sk_type) {
-	case SOCK_STREAM:
-		prot = tcp_bpf_get_proto(sk, psock);
-		break;
-
-	case SOCK_DGRAM:
-		prot = udp_bpf_get_proto(sk, psock);
-		break;
-
-	default:
+	if (!sk->sk_prot->update_proto)
 		return -EINVAL;
-	}
-
-	if (IS_ERR(prot))
-		return PTR_ERR(prot);
-
-	sk_psock_update_proto(sk, psock, prot);
-	return 0;
+	psock->saved_update_proto = sk->sk_prot->update_proto;
+	return sk->sk_prot->update_proto(sk, false);
 }
 
 static struct sk_psock *sock_map_psock_get_checked(struct sock *sk)
@@ -570,7 +554,7 @@ static bool sock_map_redirect_allowed(const struct sock *sk)
 
 static bool sock_map_sk_is_suitable(const struct sock *sk)
 {
-	return sk_is_tcp(sk) || sk_is_udp(sk);
+	return !!sk->sk_prot->update_proto;
 }
 
 static bool sock_map_sk_state_allowed(const struct sock *sk)

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
@@ -601,19 +601,36 @@ static int tcp_bpf_assert_proto_ops(struct proto *ops)
 	       ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP;
 }
 
-struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
+int tcp_bpf_update_proto(struct sock *sk, 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;
 
+	if (restore) {
+		if (inet_csk_has_ulp(sk)) {
+			tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
+		} else {
+			sk->sk_write_space = psock->saved_write_space;
+			/* Pairs with lockless read in sk_clone_lock() */
+			WRITE_ONCE(sk->sk_prot, psock->sk_proto);
+		}
+		return 0;
+	}
+
+	if (inet_csk_has_ulp(sk))
+		return -EINVAL;
+
 	if (sk->sk_family == AF_INET6) {
 		if (tcp_bpf_assert_proto_ops(psock->sk_proto))
-			return ERR_PTR(-EINVAL);
+			return -EINVAL;
 
 		tcp_bpf_check_v6_needs_rebuild(psock->sk_proto);
 	}
 
-	return &tcp_bpf_prots[family][config];
+	/* Pairs with lockless read in sk_clone_lock() */
+	WRITE_ONCE(sk->sk_prot, &tcp_bpf_prots[family][config]);
+	return 0;
 }
 
 /* If a child got cloned from a listening socket that had tcp_bpf

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
@@ -2806,6 +2806,9 @@ struct proto tcp_prot = {
 	.hash			= inet_hash,
 	.unhash			= inet_unhash,
 	.get_port		= inet_csk_get_port,
+#ifdef CONFIG_BPF_SYSCALL
+	.update_proto		= tcp_bpf_update_proto,
+#endif
 	.enter_memory_pressure	= tcp_enter_memory_pressure,
 	.leave_memory_pressure	= tcp_leave_memory_pressure,
 	.stream_memory_free	= tcp_stream_memory_free,

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
@@ -2849,6 +2849,9 @@ struct proto udp_prot = {
 	.unhash			= udp_lib_unhash,
 	.rehash			= udp_v4_rehash,
 	.get_port		= udp_v4_get_port,
+#ifdef CONFIG_BPF_SYSCALL
+	.update_proto		= udp_bpf_update_proto,
+#endif
 	.memory_allocated	= &udp_memory_allocated,
 	.sysctl_mem		= sysctl_udp_mem,
 	.sysctl_wmem_offset	= offsetof(struct net, ipv4.sysctl_udp_wmem_min),

diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c
@@ -41,12 +41,22 @@ static int __init udp_bpf_v4_build_proto(void)
 }
 core_initcall(udp_bpf_v4_build_proto);
 
-struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
+int udp_bpf_update_proto(struct sock *sk, 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;
+		/* Pairs with lockless read in sk_clone_lock() */
+		WRITE_ONCE(sk->sk_prot, psock->sk_proto);
+		return 0;
+	}
 
 	if (sk->sk_family == AF_INET6)
 		udp_bpf_check_v6_needs_rebuild(psock->sk_proto);
 
-	return &udp_bpf_prots[family];
+	/* Pairs with lockless read in sk_clone_lock() */
+	WRITE_ONCE(sk->sk_prot, &udp_bpf_prots[family]);
+	return 0;
 }
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
@@ -2134,6 +2134,9 @@ struct proto tcpv6_prot = {
 	.hash			= inet6_hash,
 	.unhash			= inet_unhash,
 	.get_port		= inet_csk_get_port,
+#ifdef CONFIG_BPF_SYSCALL
+	.update_proto		= tcp_bpf_update_proto,
+#endif
 	.enter_memory_pressure	= tcp_enter_memory_pressure,
 	.leave_memory_pressure	= tcp_leave_memory_pressure,
 	.stream_memory_free	= tcp_stream_memory_free,

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
@@ -1713,6 +1713,9 @@ struct proto udpv6_prot = {
 	.unhash			= udp_lib_unhash,
 	.rehash			= udp_v6_rehash,
 	.get_port		= udp_v6_get_port,
+#ifdef CONFIG_BPF_SYSCALL
+	.update_proto		= udp_bpf_update_proto,
+#endif
 	.memory_allocated	= &udp_memory_allocated,
 	.sysctl_mem		= sysctl_udp_mem,
 	.sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_udp_wmem_min),