[RFC PATCH bpf-next 08/13] bpf: Alloc and free bpf_map id in bpf namespace
From: Yafang Shao
Date: Sun Mar 26 2023 - 05:22:51 EST
We only expose the bpf map id under current bpf namespace to user. The
map->id is still the id in the init bpf namespace.
The result as follows,
Run bpftool in a new bpf namespace
$ bpftool map show
4: array name kprobe_b.rodata flags 0x80
key 4B value 37B max_entries 1 memlock 360B
btf_id 159 frozen
pids kprobe(20490)
5: array name kprobe_b.data flags 0x400
key 4B value 4B max_entries 1 memlock 8192B
btf_id 159
pids kprobe(20490)
$ bpftool prog show
91: kprobe name kretprobe_run tag 0de47cc241a2b1b3 gpl
loaded_at 2023-03-20T22:19:16+0800 uid 0
xlated 56B jited 39B memlock 4096B map_ids 4
btf_id 159
pids kprobe(20490)
93: kprobe name kprobe_run tag bf163b23cd3b174d gpl
loaded_at 2023-03-20T22:19:16+0800 uid 0
xlated 48B jited 35B memlock 4096B map_ids 4
btf_id 159
pids kprobe(20490)
At the same time, run bpftool in init bpf namespace,
$ bpftool map show
48: array name kprobe_b.rodata flags 0x80
key 4B value 37B max_entries 1 memlock 360B
btf_id 159 frozen
pids kprobe(20490)
49: array name kprobe_b.data flags 0x400
key 4B value 4B max_entries 1 memlock 8192B
btf_id 159
pids kprobe(20490)
$ bpftool prog show
91: kprobe name kretprobe_run tag 0de47cc241a2b1b3 gpl
loaded_at 2023-03-20T22:19:16+0800 uid 0
xlated 56B jited 39B memlock 4096B map_ids 48
btf_id 159
pids kprobe(20490)
93: kprobe name kprobe_run tag bf163b23cd3b174d gpl
loaded_at 2023-03-20T22:19:16+0800 uid 0
xlated 48B jited 35B memlock 4096B map_ids 48
btf_id 159
pids kprobe(20490)
In init bpf namespace, bpftool can also show other bpf maps, but the
bpftool running in the new bpf namespace can't.
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
include/linux/bpf.h | 3 +-
kernel/bpf/bpf_namespace.c | 1 +
kernel/bpf/offload.c | 3 +-
kernel/bpf/syscall.c | 58 ++++++++++---------------------
tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 7 +++-
5 files changed, 30 insertions(+), 42 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c94034a..2a1f19c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -29,6 +29,7 @@
#include <linux/rcupdate_trace.h>
#include <linux/static_call.h>
#include <linux/memcontrol.h>
+#include <linux/bpf_namespace.h>
struct bpf_verifier_env;
struct bpf_verifier_log;
@@ -279,6 +280,7 @@ struct bpf_map {
} owner;
bool bypass_spec_v1;
bool frozen; /* write-once; write-protected by freeze_mutex */
+ struct bpf_obj_id *obj_id;
};
static inline const char *btf_field_type_name(enum btf_field_type type)
@@ -1939,7 +1941,6 @@ struct bpf_prog *bpf_prog_get_type_dev(u32 ufd, enum bpf_prog_type type,
void bpf_prog_put(struct bpf_prog *prog);
void bpf_prog_free_id(struct bpf_prog *prog);
-void bpf_map_free_id(struct bpf_map *map);
struct btf_field *btf_record_find(const struct btf_record *rec,
u32 offset, u32 field_mask);
diff --git a/kernel/bpf/bpf_namespace.c b/kernel/bpf/bpf_namespace.c
index 1e98d1d..6a6ef70 100644
--- a/kernel/bpf/bpf_namespace.c
+++ b/kernel/bpf/bpf_namespace.c
@@ -11,6 +11,7 @@
#include <linux/bpf_namespace.h>
#define MAX_BPF_NS_LEVEL 32
+DEFINE_SPINLOCK(map_idr_lock);
static struct kmem_cache *bpfns_cachep;
static struct kmem_cache *obj_id_cache[MAX_PID_NS_LEVEL];
static struct ns_common *bpfns_get(struct task_struct *task);
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index aec70e0..7a90ebe 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -25,6 +25,7 @@
#include <linux/rhashtable.h>
#include <linux/rtnetlink.h>
#include <linux/rwsem.h>
+#include <linux/bpf_namespace.h>
/* Protects offdevs, members of bpf_offload_netdev and offload members
* of all progs.
@@ -145,7 +146,7 @@ static void __bpf_map_offload_destroy(struct bpf_offloaded_map *offmap)
* refcnt to drop to be freed.
*/
if (map->id) {
- bpf_map_free_id(map);
+ bpf_free_obj_id(map->obj_id, MAP_OBJ_ID);
map->id = 0;
}
list_del_init(&offmap->offloads);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f24e550..1335200 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -35,6 +35,7 @@
#include <linux/rcupdate_trace.h>
#include <linux/memcontrol.h>
#include <linux/trace_events.h>
+#include <linux/bpf_namespace.h>
#define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
(map)->map_type == BPF_MAP_TYPE_CGROUP_ARRAY || \
@@ -49,8 +50,6 @@
DEFINE_PER_CPU(int, bpf_prog_active);
static DEFINE_IDR(prog_idr);
DEFINE_SPINLOCK(prog_idr_lock);
-static DEFINE_IDR(map_idr);
-DEFINE_SPINLOCK(map_idr_lock);
static DEFINE_IDR(link_idr);
DEFINE_SPINLOCK(link_idr_lock);
@@ -375,30 +374,6 @@ void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr)
map->map_extra = attr->map_extra;
}
-static int bpf_map_alloc_id(struct bpf_map *map)
-{
- int id;
-
- idr_preload(GFP_KERNEL);
- spin_lock_bh(&map_idr_lock);
- id = idr_alloc_cyclic(&map_idr, map, 1, INT_MAX, GFP_ATOMIC);
- spin_unlock_bh(&map_idr_lock);
- idr_preload_end();
-
- return id;
-}
-
-void bpf_map_free_id(struct bpf_map *map)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&map_idr_lock, flags);
-
- idr_remove(&map_idr, map->id);
-
- spin_unlock_irqrestore(&map_idr_lock, flags);
-}
-
#ifdef CONFIG_MEMCG_KMEM
static void bpf_map_save_memcg(struct bpf_map *map)
{
@@ -737,9 +712,9 @@ static void bpf_map_put_uref(struct bpf_map *map)
void bpf_map_put(struct bpf_map *map)
{
if (atomic64_dec_and_test(&map->refcnt)) {
- /* bpf_map_free_id() must be called first. */
+ /* bpf_free_obj_id() must be called first. */
if (map->id) {
- bpf_map_free_id(map);
+ bpf_free_obj_id(map->obj_id, MAP_OBJ_ID);
map->id = 0;
}
btf_put(map->btf);
@@ -817,7 +792,7 @@ static void bpf_map_show_fdinfo(struct seq_file *m, struct file *filp)
map->map_flags,
(unsigned long long)map->map_extra,
bpf_map_memory_usage(map),
- map->id,
+ bpf_obj_id_vnr(map->obj_id),
READ_ONCE(map->frozen));
if (type) {
seq_printf(m, "owner_prog_type:\t%u\n", type);
@@ -1115,6 +1090,7 @@ static int map_create(union bpf_attr *attr)
{
int numa_node = bpf_map_attr_numa_node(attr);
struct btf_field_offs *foffs;
+ struct bpf_obj_id *obj_id;
struct bpf_map *map;
int f_flags;
int err;
@@ -1206,10 +1182,11 @@ static int map_create(union bpf_attr *attr)
if (err)
goto free_map_field_offs;
- err = bpf_map_alloc_id(map);
- if (err < 0)
+ obj_id = bpf_alloc_obj_id(current->nsproxy->bpf_ns, map, MAP_OBJ_ID);
+ if (IS_ERR(obj_id))
goto free_map_sec;
- map->id = err;
+ map->obj_id = obj_id;
+ map->id = bpf_obj_id_nr(obj_id);
bpf_map_save_memcg(map);
@@ -1217,7 +1194,7 @@ static int map_create(union bpf_attr *attr)
if (err < 0) {
/* failed to allocate fd.
* bpf_map_put_with_uref() is needed because the above
- * bpf_map_alloc_id() has published the map
+ * bpf_alloc_obj_id() has published the map
* to the userspace and the userspace may
* have refcnt-ed it through BPF_MAP_GET_FD_BY_ID.
*/
@@ -3709,11 +3686,12 @@ static int bpf_obj_get_next_id(const union bpf_attr *attr,
struct bpf_map *bpf_map_get_curr_or_next(u32 *id)
{
+ struct bpf_namespace *ns = current->nsproxy->bpf_ns;
struct bpf_map *map;
spin_lock_bh(&map_idr_lock);
again:
- map = idr_get_next(&map_idr, id);
+ map = idr_get_next(&ns->idr[MAP_OBJ_ID], id);
if (map) {
map = __bpf_map_inc_not_zero(map, false);
if (IS_ERR(map)) {
@@ -3791,6 +3769,7 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
{
+ struct bpf_namespace *ns = current->nsproxy->bpf_ns;
struct bpf_map *map;
u32 id = attr->map_id;
int f_flags;
@@ -3808,7 +3787,7 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
return f_flags;
spin_lock_bh(&map_idr_lock);
- map = idr_find(&map_idr, id);
+ map = idr_find(&ns->idr[MAP_OBJ_ID], id);
if (map)
map = __bpf_map_inc_not_zero(map, true);
else
@@ -3896,7 +3875,7 @@ static struct bpf_insn *bpf_insn_prepare_dump(const struct bpf_prog *prog,
map = bpf_map_from_imm(prog, imm, &off, &type);
if (map) {
insns[i].src_reg = type;
- insns[i].imm = map->id;
+ insns[i].imm = bpf_obj_id_vnr(map->obj_id);
insns[i + 1].imm = off;
continue;
}
@@ -3978,7 +3957,7 @@ static int bpf_prog_get_info_by_fd(struct file *file,
u32 i;
for (i = 0; i < ulen; i++)
- if (put_user(prog->aux->used_maps[i]->id,
+ if (put_user(bpf_obj_id_vnr(prog->aux->used_maps[i]->obj_id),
&user_map_ids[i])) {
mutex_unlock(&prog->aux->used_maps_mutex);
return -EFAULT;
@@ -4242,7 +4221,7 @@ static int bpf_map_get_info_by_fd(struct file *file,
memset(&info, 0, sizeof(info));
info.type = map->map_type;
- info.id = map->id;
+ info.id = bpf_obj_id_vnr(map->obj_id);
info.key_size = map->key_size;
info.value_size = map->value_size;
info.max_entries = map->max_entries;
@@ -4994,6 +4973,7 @@ static int bpf_prog_bind_map(union bpf_attr *attr)
static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size)
{
+ struct bpf_namespace *ns = current->nsproxy->bpf_ns;
union bpf_attr attr;
bool capable;
int err;
@@ -5072,7 +5052,7 @@ static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size)
break;
case BPF_MAP_GET_NEXT_ID:
err = bpf_obj_get_next_id(&attr, uattr.user,
- &map_idr, &map_idr_lock);
+ &ns->idr[MAP_OBJ_ID], &map_idr_lock);
break;
case BPF_BTF_GET_NEXT_ID:
err = bpf_obj_get_next_id(&attr, uattr.user,
diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
index eb05ea5..a71aef7 100644
--- a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
+++ b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
@@ -24,11 +24,14 @@ enum bpf_obj_type {
static __always_inline __u32 get_obj_id(void *ent, enum bpf_obj_type type)
{
+ void *obj_id;
+
switch (type) {
case BPF_OBJ_PROG:
return BPF_CORE_READ((struct bpf_prog *)ent, aux, id);
case BPF_OBJ_MAP:
- return BPF_CORE_READ((struct bpf_map *)ent, id);
+ obj_id = BPF_CORE_READ((struct bpf_map *)ent, obj_id);
+ break;
case BPF_OBJ_BTF:
return BPF_CORE_READ((struct btf *)ent, id);
case BPF_OBJ_LINK:
@@ -36,6 +39,8 @@ static __always_inline __u32 get_obj_id(void *ent, enum bpf_obj_type type)
default:
return 0;
}
+
+ return bpf_find_obj_id(obj_id);
}
/* could be used only with BPF_LINK_TYPE_PERF_EVENT links */
--
1.8.3.1