[PATCH bpf 2/2] bpf: sockmap: reject invalid attach_flags

[Lorenz Bauer]

Using BPF_PROG_ATTACH on a sockmap program currently understands no
flags, but accepts any value. Return EINVAL if any flags are specified.

Signed-off-by: Lorenz Bauer <l...@cloudflare.com>
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
---
 net/core/sock_map.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 00a26cf2cfe9..6f0894909138 100644
--- 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_attr *attr, struct 
bpf_prog *prog)
        struct fd f;
        int ret;
 
+       if (attr->attach_flags)
+               return -EINVAL;
+
        f = fdget(ufd);
        map = __bpf_map_get(f);
        if (IS_ERR(map))
-- 
2.25.1