bpf: Propagate modified uaddrlen from cgroup sockaddr programs

As prep for adding unix socket support to the cgroup sockaddr hooks,
let's propagate the sockaddr length back to the caller after running
a bpf cgroup sockaddr hook program. While not important for AF_INET or
AF_INET6, the sockaddr length is important when working with AF_UNIX
sockaddrs as the size of the sockaddr cannot be determined just from the
address family or the sockaddr's contents.

__cgroup_bpf_run_filter_sock_addr() is modified to take the uaddrlen as
an input/output argument. After running the program, the modified sockaddr
length is stored in the uaddrlen pointer.

Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-3-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

4 files changed, 11 insertions, 8 deletions

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 6337fb4504fd..c35d302a3da9 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -454,7 +454,7 @@ int inet6_bind_sk(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	/* BPF prog is run before any checks are done so that if the prog
 	 * changes context in a wrong way it will be caught.
 	 */
-	err = BPF_CGROUP_RUN_PROG_INET_BIND_LOCK(sk, uaddr,
+	err = BPF_CGROUP_RUN_PROG_INET_BIND_LOCK(sk, uaddr, &addr_len,
 						 CGROUP_INET6_BIND, &flags);
 	if (err)
 		return err;
@@ -520,6 +520,7 @@ int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
 		  int peer)
 {
 	struct sockaddr_in6 *sin = (struct sockaddr_in6 *)uaddr;
+	int sin_addr_len = sizeof(*sin);
 	struct sock *sk = sock->sk;
 	struct inet_sock *inet = inet_sk(sk);
 	struct ipv6_pinfo *np = inet6_sk(sk);
@@ -539,7 +540,7 @@ int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
 		sin->sin6_addr = sk->sk_v6_daddr;
 		if (inet6_test_bit(SNDFLOW, sk))
 			sin->sin6_flowinfo = np->flow_label;
-		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin,
+		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin, &sin_addr_len,
 				       CGROUP_INET6_GETPEERNAME);
 	} else {
 		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
@@ -547,13 +548,13 @@ int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
 		else
 			sin->sin6_addr = sk->sk_v6_rcv_saddr;
 		sin->sin6_port = inet->inet_sport;
-		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin,
+		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin, &sin_addr_len,
 				       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);
+	return sin_addr_len;
 }
 EXPORT_SYMBOL(inet6_getname);
 
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index e8fb0d275cc2..d2098dd4ceae 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -56,7 +56,7 @@ static int ping_v6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
 	if (addr_len < SIN6_LEN_RFC2133)
 		return -EINVAL;
 
-	return BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr);
+	return BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr, &addr_len);
 }
 
 static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 94afb8d0f2d0..3a1e76a2d33e 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -135,7 +135,7 @@ static int tcp_v6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
 
 	sock_owned_by_me(sk);
 
-	return BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr);
+	return BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr, &addr_len);
 }
 
 static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 5e9312eefed0..622b10a549f7 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -410,7 +410,8 @@ try_again:
 		*addr_len = sizeof(*sin6);
 
 		BPF_CGROUP_RUN_PROG_UDP6_RECVMSG_LOCK(sk,
-						      (struct sockaddr *)sin6);
+						      (struct sockaddr *)sin6,
+						      addr_len);
 	}
 
 	if (udp_test_bit(GRO_ENABLED, sk))
@@ -1157,7 +1158,7 @@ static int udpv6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
 	if (addr_len < SIN6_LEN_RFC2133)
 		return -EINVAL;
 
-	return BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr);
+	return BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr, &addr_len);
 }
 
 /**
@@ -1510,6 +1511,7 @@ do_udp_sendmsg:
 	if (cgroup_bpf_enabled(CGROUP_UDP6_SENDMSG) && !connected) {
 		err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
 					   (struct sockaddr *)sin6,
+					   &addr_len,
 					   &fl6->saddr);
 		if (err)
 			goto out_no_dst;