inet: remove races in inet{6}_getname()

syzbot reported data-races in inet_getname() multiple times,
it is time we fix this instead of pretending applications
should not trigger them.

getsockname() and getpeername() are not really considered fast path.

v2: added the missing BPF_CGROUP_RUN_SA_PROG() declaration
    needed when CONFIG_CGROUP_BPF=n, as reported by
    kernel test robot <lkp@intel.com>

syzbot typical report:

BUG: KCSAN: data-race in __inet_hash_connect / inet_getname

write to 0xffff888136d66cf8 of 2 bytes by task 14374 on cpu 1:
 __inet_hash_connect+0x7ec/0x950 net/ipv4/inet_hashtables.c:831
 inet_hash_connect+0x85/0x90 net/ipv4/inet_hashtables.c:853
 tcp_v4_connect+0x782/0xbb0 net/ipv4/tcp_ipv4.c:275
 __inet_stream_connect+0x156/0x6e0 net/ipv4/af_inet.c:664
 inet_stream_connect+0x44/0x70 net/ipv4/af_inet.c:728
 __sys_connect_file net/socket.c:1896 [inline]
 __sys_connect+0x254/0x290 net/socket.c:1913
 __do_sys_connect net/socket.c:1923 [inline]
 __se_sys_connect net/socket.c:1920 [inline]
 __x64_sys_connect+0x3d/0x50 net/socket.c:1920
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888136d66cf8 of 2 bytes by task 14408 on cpu 0:
 inet_getname+0x11f/0x170 net/ipv4/af_inet.c:790
 __sys_getsockname+0x11d/0x1b0 net/socket.c:1946
 __do_sys_getsockname net/socket.c:1961 [inline]
 __se_sys_getsockname net/socket.c:1958 [inline]
 __x64_sys_getsockname+0x3e/0x50 net/socket.c:1958
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000 -> 0xdee0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14408 Comm: syz-executor.3 Not tainted 5.15.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Link: https://lore.kernel.org/r/20211026213014.3026708-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/bpf-cgroup.h

@@ -517,6 +517,7 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,
 
 #define cgroup_bpf_enabled(atype) (0)
 #define BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, atype, t_ctx) ({ 0; })
+#define BPF_CGROUP_RUN_SA_PROG(sk, uaddr, atype) ({ 0; })
 #define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (0)
 #define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; })

net/ipv4/af_inet.c

@@ -769,26 +769,28 @@ int inet_getname(struct socket *sock, struct sockaddr *uaddr,
 	DECLARE_SOCKADDR(struct sockaddr_in *, sin, uaddr);
 
 	sin->sin_family = AF_INET;
+	lock_sock(sk);
 	if (peer) {
 		if (!inet->inet_dport ||
 		    (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
-		     peer == 1))
+		     peer == 1)) {
+			release_sock(sk);
 			return -ENOTCONN;
+		}
 		sin->sin_port = inet->inet_dport;
 		sin->sin_addr.s_addr = inet->inet_daddr;
-		BPF_CGROUP_RUN_SA_PROG_LOCK(sk, (struct sockaddr *)sin,
-					    CGROUP_INET4_GETPEERNAME,
-					    NULL);
+		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin,
+				       CGROUP_INET4_GETPEERNAME);
 	} else {
 		__be32 addr = inet->inet_rcv_saddr;
 		if (!addr)
 			addr = inet->inet_saddr;
 		sin->sin_port = inet->inet_sport;
 		sin->sin_addr.s_addr = addr;
-		BPF_CGROUP_RUN_SA_PROG_LOCK(sk, (struct sockaddr *)sin,
-					    CGROUP_INET4_GETSOCKNAME,
-					    NULL);
+		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin,
+				       CGROUP_INET4_GETSOCKNAME);
 	}
+	release_sock(sk);
 	memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
 	return sizeof(*sin);
 }

net/ipv6/af_inet6.c

@@ -521,31 +521,32 @@ int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
 	sin->sin6_family = AF_INET6;
 	sin->sin6_flowinfo = 0;
 	sin->sin6_scope_id = 0;
+	lock_sock(sk);
 	if (peer) {
-		if (!inet->inet_dport)
-			return -ENOTCONN;
-		if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
-		    peer == 1)
+		if (!inet->inet_dport ||
+		    (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
+		    peer == 1)) {
+			release_sock(sk);
 			return -ENOTCONN;
+		}
 		sin->sin6_port = inet->inet_dport;
 		sin->sin6_addr = sk->sk_v6_daddr;
 		if (np->sndflow)
 			sin->sin6_flowinfo = np->flow_label;
-		BPF_CGROUP_RUN_SA_PROG_LOCK(sk, (struct sockaddr *)sin,
-					    CGROUP_INET6_GETPEERNAME,
-					    NULL);
+		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin,
+				       CGROUP_INET6_GETPEERNAME);
 	} else {
 		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 			sin->sin6_addr = np->saddr;
 		else
 			sin->sin6_addr = sk->sk_v6_rcv_saddr;
 		sin->sin6_port = inet->inet_sport;
-		BPF_CGROUP_RUN_SA_PROG_LOCK(sk, (struct sockaddr *)sin,
-					    CGROUP_INET6_GETSOCKNAME,
-					    NULL);
+		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin,
+				       CGROUP_INET6_GETSOCKNAME);
 	}
 	sin->sin6_scope_id = ipv6_iface_scope_id(&sin->sin6_addr,
 						 sk->sk_bound_dev_if);
+	release_sock(sk);
 	return sizeof(*sin);
 }
 EXPORT_SYMBOL(inet6_getname);