[PATCH 5.7 242/244] bpf: sockmap: Check value of unused args to BPF_PROG_ATTACH

[Greg Kroah-Hartman]

From: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>

commit 9b2b09717e1812e450782a43ca0c2790651cf380 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: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20200629095630.7933-4-lmb@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/core/sock_map.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -70,6 +70,9 @@ int sock_map_get_from_fd(const union bpf
 	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))