bpf: fix attach type BPF_LIRC_MODE2 dependency wrt CONFIG_CGROUP_BPF

If the kernel is compiled with CONFIG_CGROUP_BPF not enabled, it is not
possible to attach, detach or query IR BPF programs to /dev/lircN devices,
making them impossible to use. For embedded devices, it should be possible
to use IR decoding without cgroups or CONFIG_CGROUP_BPF enabled.

This change requires some refactoring, since bpf_prog_{attach,detach,query}
functions are now always compiled, but their code paths for cgroups need
moving out. Rather than a #ifdef CONFIG_CGROUP_BPF in kernel/bpf/syscall.c,
moving them to kernel/bpf/cgroup.c and kernel/bpf/sockmap.c does not
require #ifdefs since that is already conditionally compiled.

Fixes: f4364dcfc86d ("media: rc: introduce BPF_PROG_LIRC_MODE2")
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 18 insertions, 0 deletions

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 52a91d816c0e..81d0c55a77aa 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -1915,6 +1915,24 @@ int sock_map_prog(struct bpf_map *map, struct bpf_prog *prog, u32 type)
 	return 0;
 }
 
+int sockmap_get_from_fd(const union bpf_attr *attr, int type,
+			struct bpf_prog *prog)
+{
+	int ufd = attr->target_fd;
+	struct bpf_map *map;
+	struct fd f;
+	int err;
+
+	f = fdget(ufd);
+	map = __bpf_map_get(f);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	err = sock_map_prog(map, prog, attr->attach_type);
+	fdput(f);
+	return err;
+}
+
 static void *sock_map_lookup(struct bpf_map *map, void *key)
 {
 	return NULL;