Commit fdb5c453 authored by Sean Young's avatar Sean Young Committed by Daniel Borkmann
Browse files

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: f4364dcf ("media: rc: introduce BPF_PROG_LIRC_MODE2")
Signed-off-by: default avatarSean Young <sean@mess.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 68d676a0

drivers/media/rc/bpf-lirc.c

+2 −12
Original line number Diff line number Diff line
@@ -207,29 +207,19 @@ void lirc_bpf_free(struct rc_dev *rcdev) 
	bpf_prog_array_free(rcdev->raw->progs);

}



int lirc_prog_attach(const union bpf_attr *attr)

int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)

{

	struct bpf_prog *prog;

	struct rc_dev *rcdev;

	int ret;



	if (attr->attach_flags)

		return -EINVAL;



	prog = bpf_prog_get_type(attr->attach_bpf_fd,

				 BPF_PROG_TYPE_LIRC_MODE2);

	if (IS_ERR(prog))

		return PTR_ERR(prog);



	rcdev = rc_dev_get_from_fd(attr->target_fd);

	if (IS_ERR(rcdev)) {

		bpf_prog_put(prog);

	if (IS_ERR(rcdev))

		return PTR_ERR(rcdev);

	}



	ret = lirc_bpf_attach(rcdev, prog);

	if (ret)

		bpf_prog_put(prog);



	put_device(&rcdev->dev);

include/linux/bpf-cgroup.h

+26 −0
Original line number Diff line number Diff line
@@ -188,12 +188,38 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor, 
									      \

	__ret;								      \

})

int cgroup_bpf_prog_attach(const union bpf_attr *attr,

			   enum bpf_prog_type ptype, struct bpf_prog *prog);

int cgroup_bpf_prog_detach(const union bpf_attr *attr,

			   enum bpf_prog_type ptype);

int cgroup_bpf_prog_query(const union bpf_attr *attr,

			  union bpf_attr __user *uattr);

#else



struct bpf_prog;

struct cgroup_bpf {};

static inline void cgroup_bpf_put(struct cgroup *cgrp) {}

static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }



static inline int cgroup_bpf_prog_attach(const union bpf_attr *attr,

					 enum bpf_prog_type ptype,

					 struct bpf_prog *prog)

{

	return -EINVAL;

}



static inline int cgroup_bpf_prog_detach(const union bpf_attr *attr,

					 enum bpf_prog_type ptype)

{

	return -EINVAL;

}



static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,

					union bpf_attr __user *uattr)

{

	return -EINVAL;

}



#define cgroup_bpf_enabled (0)

#define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (0)

#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })

include/linux/bpf.h

+8 −0
Original line number Diff line number Diff line
@@ -696,6 +696,8 @@ static inline void bpf_map_offload_map_free(struct bpf_map *map) 
struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key);

struct sock  *__sock_hash_lookup_elem(struct bpf_map *map, void *key);

int sock_map_prog(struct bpf_map *map, struct bpf_prog *prog, u32 type);

int sockmap_get_from_fd(const union bpf_attr *attr, int type,

			struct bpf_prog *prog);

#else

static inline struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key)

{
@@ -714,6 +716,12 @@ static inline int sock_map_prog(struct bpf_map *map, 
{

	return -EOPNOTSUPP;

}



static inline int sockmap_get_from_fd(const union bpf_attr *attr, int type,

				      struct bpf_prog *prog)

{

	return -EINVAL;

}

#endif



#if defined(CONFIG_XDP_SOCKETS)

include/linux/bpf_lirc.h

+3 −2
Original line number Diff line number Diff line
@@ -5,11 +5,12 @@ 
#include <uapi/linux/bpf.h>



#ifdef CONFIG_BPF_LIRC_MODE2

int lirc_prog_attach(const union bpf_attr *attr);

int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog);

int lirc_prog_detach(const union bpf_attr *attr);

int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr);

#else

static inline int lirc_prog_attach(const union bpf_attr *attr)

static inline int lirc_prog_attach(const union bpf_attr *attr,

				   struct bpf_prog *prog)

{

	return -EINVAL;

}

kernel/bpf/cgroup.c

+54 −0
Original line number Diff line number Diff line
@@ -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

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