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Commit f3f1c054 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

bpf: Introduce bpf_map ID 



This patch generates an unique ID for each created bpf_map.
The approach is similar to the earlier patch for bpf_prog ID.

It is worth to note that the bpf_map's ID and bpf_prog's ID
are in two independent ID spaces and both have the same valid range:
[1, INT_MAX).

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 dc4bb0e2

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ struct bpf_map { 
	u32 max_entries;

	u32 map_flags;

	u32 pages;

	u32 id;

	struct user_struct *user;

	const struct bpf_map_ops *ops;

	struct work_struct work;

kernel/bpf/syscall.c

+33 −1
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ 
DEFINE_PER_CPU(int, bpf_prog_active);

static DEFINE_IDR(prog_idr);

static DEFINE_SPINLOCK(prog_idr_lock);

static DEFINE_IDR(map_idr);

static DEFINE_SPINLOCK(map_idr_lock);



int sysctl_unprivileged_bpf_disabled __read_mostly;
@@ -117,6 +119,29 @@ static void bpf_map_uncharge_memlock(struct bpf_map *map) 
	free_uid(user);

}



static int bpf_map_alloc_id(struct bpf_map *map)

{

	int id;



	spin_lock_bh(&map_idr_lock);

	id = idr_alloc_cyclic(&map_idr, map, 1, INT_MAX, GFP_ATOMIC);

	if (id > 0)

		map->id = id;

	spin_unlock_bh(&map_idr_lock);



	if (WARN_ON_ONCE(!id))

		return -ENOSPC;



	return id > 0 ? 0 : id;

}



static void bpf_map_free_id(struct bpf_map *map)

{

	spin_lock_bh(&map_idr_lock);

	idr_remove(&map_idr, map->id);

	spin_unlock_bh(&map_idr_lock);

}



/* called from workqueue */

static void bpf_map_free_deferred(struct work_struct *work)

{
@@ -141,6 +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(map);

		INIT_WORK(&map->work, bpf_map_free_deferred);

		schedule_work(&map->work);

	}
@@ -239,14 +265,20 @@ static int map_create(union bpf_attr *attr) 
	if (err)

		goto free_map_nouncharge;



	err = bpf_map_alloc_id(map);

	if (err)

		goto free_map;



	err = bpf_map_new_fd(map);

	if (err < 0)

		/* failed to allocate fd */

		goto free_map;

		goto free_id;



	trace_bpf_map_create(map, err);

	return err;



free_id:

	bpf_map_free_id(map);

free_map:

	bpf_map_uncharge_memlock(map);

free_map_nouncharge: