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, 54 insertions, 0 deletions

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index f7c00bd6f8e4..3d83ee7df381 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -428,6 +428,60 @@ int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
 	return ret;
 }
 
+int cgroup_bpf_prog_attach(const union bpf_attr *attr,
+			   enum bpf_prog_type ptype, struct bpf_prog *prog)
+{
+	struct cgroup *cgrp;
+	int ret;
+
+	cgrp = cgroup_get_from_fd(attr->target_fd);
+	if (IS_ERR(cgrp))
+		return PTR_ERR(cgrp);
+
+	ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
+				attr->attach_flags);
+	cgroup_put(cgrp);
+	return ret;
+}
+
+int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
+{
+	struct bpf_prog *prog;
+	struct cgroup *cgrp;
+	int ret;
+
+	cgrp = cgroup_get_from_fd(attr->target_fd);
+	if (IS_ERR(cgrp))
+		return PTR_ERR(cgrp);
+
+	prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
+	if (IS_ERR(prog))
+		prog = NULL;
+
+	ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, 0);
+	if (prog)
+		bpf_prog_put(prog);
+
+	cgroup_put(cgrp);
+	return ret;
+}
+
+int cgroup_bpf_prog_query(const union bpf_attr *attr,
+			  union bpf_attr __user *uattr)
+{
+	struct cgroup *cgrp;
+	int ret;
+
+	cgrp = cgroup_get_from_fd(attr->query.target_fd);
+	if (IS_ERR(cgrp))
+		return PTR_ERR(cgrp);
+
+	ret = cgroup_bpf_query(cgrp, attr, uattr);
+
+	cgroup_put(cgrp);
+	return ret;
+}
+
 /**
  * __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
  * @sk: The socket sending or receiving traffic