Commit ef15314a authored by YiFei Zhu's avatar YiFei Zhu Committed by Alexei Starovoitov
Browse files

bpf: Add BPF_PROG_BIND_MAP syscall 



This syscall binds a map to a program. Returns success if the map is
already bound to the program.

Signed-off-by: default avatarYiFei Zhu <zhuyifei@google.com>
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Cc: YiFei Zhu <zhuyifei1999@gmail.com>
Link: https://lore.kernel.org/bpf/20200915234543.3220146-3-sdf@google.com
parent 984fe94f

include/uapi/linux/bpf.h

+7 −0
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ enum bpf_cmd { 
	BPF_ENABLE_STATS,

	BPF_ITER_CREATE,

	BPF_LINK_DETACH,

	BPF_PROG_BIND_MAP,

};



enum bpf_map_type {
@@ -658,6 +659,12 @@ union bpf_attr { 
		__u32		flags;

	} iter_create;



	struct { /* struct used by BPF_PROG_BIND_MAP command */

		__u32		prog_fd;

		__u32		map_fd;

		__u32		flags;		/* extra flags */

	} prog_bind_map;



} __attribute__((aligned(8)));



/* The description below is an attempt at providing documentation to eBPF

kernel/bpf/syscall.c

+63 −0
Original line number Diff line number Diff line
@@ -4161,6 +4161,66 @@ static int bpf_iter_create(union bpf_attr *attr) 
	return err;

}



#define BPF_PROG_BIND_MAP_LAST_FIELD prog_bind_map.flags



static int bpf_prog_bind_map(union bpf_attr *attr)

{

	struct bpf_prog *prog;

	struct bpf_map *map;

	struct bpf_map **used_maps_old, **used_maps_new;

	int i, ret = 0;



	if (CHECK_ATTR(BPF_PROG_BIND_MAP))

		return -EINVAL;



	if (attr->prog_bind_map.flags)

		return -EINVAL;



	prog = bpf_prog_get(attr->prog_bind_map.prog_fd);

	if (IS_ERR(prog))

		return PTR_ERR(prog);



	map = bpf_map_get(attr->prog_bind_map.map_fd);

	if (IS_ERR(map)) {

		ret = PTR_ERR(map);

		goto out_prog_put;

	}



	mutex_lock(&prog->aux->used_maps_mutex);



	used_maps_old = prog->aux->used_maps;



	for (i = 0; i < prog->aux->used_map_cnt; i++)

		if (used_maps_old[i] == map)

			goto out_unlock;



	used_maps_new = kmalloc_array(prog->aux->used_map_cnt + 1,

				      sizeof(used_maps_new[0]),

				      GFP_KERNEL);

	if (!used_maps_new) {

		ret = -ENOMEM;

		goto out_unlock;

	}



	memcpy(used_maps_new, used_maps_old,

	       sizeof(used_maps_old[0]) * prog->aux->used_map_cnt);

	used_maps_new[prog->aux->used_map_cnt] = map;



	prog->aux->used_map_cnt++;

	prog->aux->used_maps = used_maps_new;



	kfree(used_maps_old);



out_unlock:

	mutex_unlock(&prog->aux->used_maps_mutex);



	if (ret)

		bpf_map_put(map);

out_prog_put:

	bpf_prog_put(prog);

	return ret;

}



SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)

{

	union bpf_attr attr;
@@ -4294,6 +4354,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz 
	case BPF_LINK_DETACH:

		err = link_detach(&attr);

		break;

	case BPF_PROG_BIND_MAP:

		err = bpf_prog_bind_map(&attr);

		break;

	default:

		err = -EINVAL;

		break;

tools/include/uapi/linux/bpf.h

+7 −0
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ enum bpf_cmd { 
	BPF_ENABLE_STATS,

	BPF_ITER_CREATE,

	BPF_LINK_DETACH,

	BPF_PROG_BIND_MAP,

};



enum bpf_map_type {
@@ -658,6 +659,12 @@ union bpf_attr { 
		__u32		flags;

	} iter_create;



	struct { /* struct used by BPF_PROG_BIND_MAP command */

		__u32		prog_fd;

		__u32		map_fd;

		__u32		flags;		/* extra flags */

	} prog_bind_map;



} __attribute__((aligned(8)));



/* The description below is an attempt at providing documentation to eBPF