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Commit 0a4c58f5 authored by Roman Gushchin's avatar Roman Gushchin Committed by Daniel Borkmann
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bpf: add ability to charge bpf maps memory dynamically 



This commits extends existing bpf maps memory charging API
to support dynamic charging/uncharging.

This is required to account memory used by maps,
if all entries are created dynamically after
the map initialization.

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent fbeb1603

include/linux/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -435,6 +435,8 @@ struct bpf_map * __must_check bpf_map_inc(struct bpf_map *map, bool uref); 
void bpf_map_put_with_uref(struct bpf_map *map);

void bpf_map_put(struct bpf_map *map);

int bpf_map_precharge_memlock(u32 pages);

int bpf_map_charge_memlock(struct bpf_map *map, u32 pages);

void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages);

void *bpf_map_area_alloc(size_t size, int numa_node);

void bpf_map_area_free(void *base);

void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr);

kernel/bpf/syscall.c

+43 −15
Original line number Diff line number Diff line
@@ -181,32 +181,60 @@ int bpf_map_precharge_memlock(u32 pages) 
	return 0;

}



static int bpf_map_charge_memlock(struct bpf_map *map)

static int bpf_charge_memlock(struct user_struct *user, u32 pages)

{

	struct user_struct *user = get_current_user();

	unsigned long memlock_limit;

	unsigned long memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;



	memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	if (atomic_long_add_return(pages, &user->locked_vm) > memlock_limit) {

		atomic_long_sub(pages, &user->locked_vm);

		return -EPERM;

	}

	return 0;

}



	atomic_long_add(map->pages, &user->locked_vm);

static void bpf_uncharge_memlock(struct user_struct *user, u32 pages)

{

	atomic_long_sub(pages, &user->locked_vm);

}



static int bpf_map_init_memlock(struct bpf_map *map)

{

	struct user_struct *user = get_current_user();

	int ret;



	if (atomic_long_read(&user->locked_vm) > memlock_limit) {

		atomic_long_sub(map->pages, &user->locked_vm);

	ret = bpf_charge_memlock(user, map->pages);

	if (ret) {

		free_uid(user);

		return -EPERM;

		return ret;

	}

	map->user = user;

	return 0;

	return ret;

}



static void bpf_map_uncharge_memlock(struct bpf_map *map)

static void bpf_map_release_memlock(struct bpf_map *map)

{

	struct user_struct *user = map->user;



	atomic_long_sub(map->pages, &user->locked_vm);

	bpf_uncharge_memlock(user, map->pages);

	free_uid(user);

}



int bpf_map_charge_memlock(struct bpf_map *map, u32 pages)

{

	int ret;



	ret = bpf_charge_memlock(map->user, pages);

	if (ret)

		return ret;

	map->pages += pages;

	return ret;

}



void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages)

{

	bpf_uncharge_memlock(map->user, pages);

	map->pages -= pages;

}



static int bpf_map_alloc_id(struct bpf_map *map)

{

	int id;
@@ -256,7 +284,7 @@ static void bpf_map_free_deferred(struct work_struct *work) 
{

	struct bpf_map *map = container_of(work, struct bpf_map, work);



	bpf_map_uncharge_memlock(map);

	bpf_map_release_memlock(map);

	security_bpf_map_free(map);

	/* implementation dependent freeing */

	map->ops->map_free(map);
@@ -492,7 +520,7 @@ static int map_create(union bpf_attr *attr) 
	if (err)

		goto free_map_nouncharge;



	err = bpf_map_charge_memlock(map);

	err = bpf_map_init_memlock(map);

	if (err)

		goto free_map_sec;
@@ -515,7 +543,7 @@ static int map_create(union bpf_attr *attr) 
	return err;



free_map:

	bpf_map_uncharge_memlock(map);

	bpf_map_release_memlock(map);

free_map_sec:

	security_bpf_map_free(map);

free_map_nouncharge: