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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: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Martin KaFai Lau 2017-06-05 12:15:48 -07:00 committed by David S. Miller
parent f3f1c054c2
commit 34ad5580f8
2 changed files with 45 additions and 0 deletions
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7
include/uapi/linux/bpf.h
View File

@ -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:

38
kernel/bpf/syscall.c
View File

@ -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;