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Commit 34ad5580 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

bpf: Add BPF_(PROG|MAP)_GET_NEXT_ID command 



This patch adds BPF_PROG_GET_NEXT_ID and BPF_MAP_GET_NEXT_ID
to allow userspace to iterate all bpf_prog IDs and bpf_map IDs.

The API is trying to be consistent with the existing
BPF_MAP_GET_NEXT_KEY.

It is currently limited to CAP_SYS_ADMIN which we can
consider to lift it in followup patches.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarAlexei Starovoitov <ast@fb.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f3f1c054

include/uapi/linux/bpf.h

+7 −0
Original line number Diff line number Diff line
@@ -82,6 +82,8 @@ enum bpf_cmd { 
	BPF_PROG_ATTACH,

	BPF_PROG_DETACH,

	BPF_PROG_TEST_RUN,

	BPF_PROG_GET_NEXT_ID,

	BPF_MAP_GET_NEXT_ID,

};



enum bpf_map_type {
@@ -209,6 +211,11 @@ union bpf_attr { 
		__u32		repeat;

		__u32		duration;

	} test;



	struct { /* anonymous struct used by BPF_*_GET_NEXT_ID */

		__u32		start_id;

		__u32		next_id;

	};

} __attribute__((aligned(8)));



/* BPF helper function descriptions:

kernel/bpf/syscall.c

+38 −0
Original line number Diff line number Diff line
@@ -166,6 +166,7 @@ static void bpf_map_put_uref(struct bpf_map *map) 
void bpf_map_put(struct bpf_map *map)

{

	if (atomic_dec_and_test(&map->refcnt)) {

		/* bpf_map_free_id() must be called first */

		bpf_map_free_id(map);

		INIT_WORK(&map->work, bpf_map_free_deferred);

		schedule_work(&map->work);
@@ -726,6 +727,7 @@ void bpf_prog_put(struct bpf_prog *prog) 
{

	if (atomic_dec_and_test(&prog->aux->refcnt)) {

		trace_bpf_prog_put_rcu(prog);

		/* bpf_prog_free_id() must be called first */

		bpf_prog_free_id(prog);

		bpf_prog_kallsyms_del(prog);

		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
@@ -1069,6 +1071,34 @@ static int bpf_prog_test_run(const union bpf_attr *attr, 
	return ret;

}



#define BPF_OBJ_GET_NEXT_ID_LAST_FIELD next_id



static int bpf_obj_get_next_id(const union bpf_attr *attr,

			       union bpf_attr __user *uattr,

			       struct idr *idr,

			       spinlock_t *lock)

{

	u32 next_id = attr->start_id;

	int err = 0;



	if (CHECK_ATTR(BPF_OBJ_GET_NEXT_ID) || next_id >= INT_MAX)

		return -EINVAL;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	next_id++;

	spin_lock_bh(lock);

	if (!idr_get_next(idr, &next_id))

		err = -ENOENT;

	spin_unlock_bh(lock);



	if (!err)

		err = put_user(next_id, &uattr->next_id);



	return err;

}



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

{

	union bpf_attr attr = {};
@@ -1146,6 +1176,14 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz 
	case BPF_PROG_TEST_RUN:

		err = bpf_prog_test_run(&attr, uattr);

		break;

	case BPF_PROG_GET_NEXT_ID:

		err = bpf_obj_get_next_id(&attr, uattr,

					  &prog_idr, &prog_idr_lock);

		break;

	case BPF_MAP_GET_NEXT_ID:

		err = bpf_obj_get_next_id(&attr, uattr,

					  &map_idr, &map_idr_lock);

		break;

	default:

		err = -EINVAL;

		break;