bpf: sockmap: Check value of unused args to BPF_PROG_ATTACH

commit 9b2b097 upstream.

Using BPF_PROG_ATTACH on a sockmap program currently understands no
flags or replace_bpf_fd, but accepts any value. Return EINVAL instead.

Fixes: 604326b ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Lorenz Bauer <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: lmb

net/core/sock_map.c

@@ -70,6 +70,9 @@ int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog)
 	struct fd f;
 	int ret;
 
+	if (attr->attach_flags || attr->replace_bpf_fd)
+		return -EINVAL;
+
 	f = fdget(ufd);
 	map = __bpf_map_get(f);
 	if (IS_ERR(map))