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 <ka...@fb.com>
Acked-by: Alexei Starovoitov <a...@fb.com>
Acked-by: Daniel Borkmann <dan...@iogearbox.net>
---
include/uapi/linux/bpf.h | 7 +++++++
kernel/bpf/syscall.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e78aece03628..629747a3f273 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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:
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4c3075b5d840..2405feedb8c1 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -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;
--
2.9.3
