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bpf: Implement bpf_local_storage for inodes 

Similar to bpf_local_storage for sockets, add local storage for inodes.
The life-cycle of storage is managed with the life-cycle of the inode.
i.e. the storage is destroyed along with the owning inode.

The BPF LSM allocates an __rcu pointer to the bpf_local_storage in the
security blob which are now stackable and can co-exist with other LSMs.

Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200825182919.1118197-6-kpsingh@chromium.org
This commit is contained in:
KP Singh 2020-08-25 20:29:17 +02:00 committed by Alexei Starovoitov
parent 450af8d0f6
commit 8ea636848a
13 changed files with 410 additions and 8 deletions
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29
include/linux/bpf_lsm.h
View File

@ -17,9 +17,28 @@
#include <linux/lsm_hook_defs.h>
#undef LSM_HOOK
struct bpf_storage_blob {
struct bpf_local_storage __rcu *storage;
};
extern struct lsm_blob_sizes bpf_lsm_blob_sizes;
int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
const struct bpf_prog *prog);
static inline struct bpf_storage_blob *bpf_inode(
const struct inode *inode)
{
if (unlikely(!inode->i_security))
return NULL;
return inode->i_security + bpf_lsm_blob_sizes.lbs_inode;
}
extern const struct bpf_func_proto bpf_inode_storage_get_proto;
extern const struct bpf_func_proto bpf_inode_storage_delete_proto;
void bpf_inode_storage_free(struct inode *inode);
#else /* !CONFIG_BPF_LSM */
static inline int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
@ -28,6 +47,16 @@ static inline int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
return -EOPNOTSUPP;
}
static inline struct bpf_storage_blob *bpf_inode(
const struct inode *inode)
{
return NULL;
}
static inline void bpf_inode_storage_free(struct inode *inode)
{
}
#endif /* CONFIG_BPF_LSM */
#endif /* _LINUX_BPF_LSM_H */

3
include/linux/bpf_types.h
View File

@ -107,6 +107,9 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_SK_STORAGE, sk_storage_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_SOCKMAP, sock_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_SOCKHASH, sock_hash_ops)
#endif
#ifdef CONFIG_BPF_LSM
BPF_MAP_TYPE(BPF_MAP_TYPE_INODE_STORAGE, inode_storage_map_ops)
#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_CPUMAP, cpu_map_ops)
#if defined(CONFIG_XDP_SOCKETS)
BPF_MAP_TYPE(BPF_MAP_TYPE_XSKMAP, xsk_map_ops)

40
include/uapi/linux/bpf.h
View File

@ -155,6 +155,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_DEVMAP_HASH,
BPF_MAP_TYPE_STRUCT_OPS,
BPF_MAP_TYPE_RINGBUF,
BPF_MAP_TYPE_INODE_STORAGE,
};
/* Note that tracing related programs such as
@ -3509,6 +3510,41 @@ union bpf_attr {
*
* **-EPERM** This helper cannot be used under the
* current sock_ops->op.
* void *bpf_inode_storage_get(struct bpf_map *map, void *inode, void *value, u64 flags)
* Description
* Get a bpf_local_storage from an *inode*.
*
* Logically, it could be thought of as getting the value from
* a *map* with *inode* as the **key**. From this
* perspective, the usage is not much different from
* **bpf_map_lookup_elem**\ (*map*, **&**\ *inode*) except this
* helper enforces the key must be an inode and the map must also
* be a **BPF_MAP_TYPE_INODE_STORAGE**.
*
* Underneath, the value is stored locally at *inode* instead of
* the *map*. The *map* is used as the bpf-local-storage
* "type". The bpf-local-storage "type" (i.e. the *map*) is
* searched against all bpf_local_storage residing at *inode*.
*
* An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be
* used such that a new bpf_local_storage will be
* created if one does not exist. *value* can be used
* together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify
* the initial value of a bpf_local_storage. If *value* is
* **NULL**, the new bpf_local_storage will be zero initialized.
* Return
* A bpf_local_storage pointer is returned on success.
*
* **NULL** if not found or there was an error in adding
* a new bpf_local_storage.
*
* int bpf_inode_storage_delete(struct bpf_map *map, void *inode)
* Description
* Delete a bpf_local_storage from an *inode*.
* Return
* 0 on success.
*
* **-ENOENT** if the bpf_local_storage cannot be found.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -3655,7 +3691,9 @@ union bpf_attr {
FN(get_task_stack), \
FN(load_hdr_opt), \
FN(store_hdr_opt), \
FN(reserve_hdr_opt),
FN(reserve_hdr_opt), \
FN(inode_storage_get), \
FN(inode_storage_delete), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper

1
kernel/bpf/Makefile
View File

@ -5,6 +5,7 @@ CFLAGS_core.o += $(call cc-disable-warning, override-init)
obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o map_iter.o task_iter.o prog_iter.o
obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o
obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o
obj-${CONFIG_BPF_LSM} += bpf_inode_storage.o
obj-$(CONFIG_BPF_SYSCALL) += disasm.o
obj-$(CONFIG_BPF_JIT) += trampoline.o
obj-$(CONFIG_BPF_SYSCALL) += btf.o

273
kernel/bpf/bpf_inode_storage.c Normal file
View File

@ -0,0 +1,273 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2019 Facebook
* Copyright 2020 Google LLC.
*/
#include <linux/rculist.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/bpf.h>
#include <linux/bpf_local_storage.h>
#include <net/sock.h>
#include <uapi/linux/sock_diag.h>
#include <uapi/linux/btf.h>
#include <linux/bpf_lsm.h>
#include <linux/btf_ids.h>
#include <linux/fdtable.h>
DEFINE_BPF_STORAGE_CACHE(inode_cache);
static struct bpf_local_storage __rcu **
inode_storage_ptr(void *owner)
{
struct inode *inode = owner;
struct bpf_storage_blob *bsb;
bsb = bpf_inode(inode);
if (!bsb)
return NULL;
return &bsb->storage;
}
static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode,
struct bpf_map *map,
bool cacheit_lockit)
{
struct bpf_local_storage *inode_storage;
struct bpf_local_storage_map *smap;
struct bpf_storage_blob *bsb;
bsb = bpf_inode(inode);
if (!bsb)
return NULL;
inode_storage = rcu_dereference(bsb->storage);
if (!inode_storage)
return NULL;
smap = (struct bpf_local_storage_map *)map;
return bpf_local_storage_lookup(inode_storage, smap, cacheit_lockit);
}
void bpf_inode_storage_free(struct inode *inode)
{
struct bpf_local_storage_elem *selem;
struct bpf_local_storage *local_storage;
bool free_inode_storage = false;
struct bpf_storage_blob *bsb;
struct hlist_node *n;
bsb = bpf_inode(inode);
if (!bsb)
return;
rcu_read_lock();
local_storage = rcu_dereference(bsb->storage);
if (!local_storage) {
rcu_read_unlock();
return;
}
/* Netiher the bpf_prog nor the bpf-map's syscall
* could be modifying the local_storage->list now.
* Thus, no elem can be added-to or deleted-from the
* local_storage->list by the bpf_prog or by the bpf-map's syscall.
*
* It is racing with bpf_local_storage_map_free() alone
* when unlinking elem from the local_storage->list and
* the map's bucket->list.
*/
raw_spin_lock_bh(&local_storage->lock);
hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
/* Always unlink from map before unlinking from
* local_storage.
*/
bpf_selem_unlink_map(selem);
free_inode_storage = bpf_selem_unlink_storage_nolock(
local_storage, selem, false);
}
raw_spin_unlock_bh(&local_storage->lock);
rcu_read_unlock();
/* free_inoode_storage should always be true as long as
* local_storage->list was non-empty.
*/
if (free_inode_storage)
kfree_rcu(local_storage, rcu);
}
static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key)
{
struct bpf_local_storage_data *sdata;
struct file *f;
int fd;
fd = *(int *)key;
f = fget_raw(fd);
if (!f)
return NULL;
sdata = inode_storage_lookup(f->f_inode, map, true);
fput(f);
return sdata ? sdata->data : NULL;
}
static int bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key,
void *value, u64 map_flags)
{
struct bpf_local_storage_data *sdata;
struct file *f;
int fd;
fd = *(int *)key;
f = fget_raw(fd);
if (!f || !inode_storage_ptr(f->f_inode))
return -EBADF;
sdata = bpf_local_storage_update(f->f_inode,
(struct bpf_local_storage_map *)map,
value, map_flags);
fput(f);
return PTR_ERR_OR_ZERO(sdata);
}
static int inode_storage_delete(struct inode *inode, struct bpf_map *map)
{
struct bpf_local_storage_data *sdata;
sdata = inode_storage_lookup(inode, map, false);
if (!sdata)
return -ENOENT;
bpf_selem_unlink(SELEM(sdata));
return 0;
}
static int bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
{
struct file *f;
int fd, err;
fd = *(int *)key;
f = fget_raw(fd);
if (!f)
return -EBADF;
err = inode_storage_delete(f->f_inode, map);
fput(f);
return err;
}
BPF_CALL_4(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
void *, value, u64, flags)
{
struct bpf_local_storage_data *sdata;
if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
return (unsigned long)NULL;
/* explicitly check that the inode_storage_ptr is not
* NULL as inode_storage_lookup returns NULL in this case and
* bpf_local_storage_update expects the owner to have a
* valid storage pointer.
*/
if (!inode_storage_ptr(inode))
return (unsigned long)NULL;
sdata = inode_storage_lookup(inode, map, true);
if (sdata)
return (unsigned long)sdata->data;
/* This helper must only called from where the inode is gurranteed
* to have a refcount and cannot be freed.
*/
if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
sdata = bpf_local_storage_update(
inode, (struct bpf_local_storage_map *)map, value,
BPF_NOEXIST);
return IS_ERR(sdata) ? (unsigned long)NULL :
(unsigned long)sdata->data;
}
return (unsigned long)NULL;
}
BPF_CALL_2(bpf_inode_storage_delete,
struct bpf_map *, map, struct inode *, inode)
{
/* This helper must only called from where the inode is gurranteed
* to have a refcount and cannot be freed.
*/
return inode_storage_delete(inode, map);
}
static int notsupp_get_next_key(struct bpf_map *map, void *key,
void *next_key)
{
return -ENOTSUPP;
}
static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr)
{
struct bpf_local_storage_map *smap;
smap = bpf_local_storage_map_alloc(attr);
if (IS_ERR(smap))
return ERR_CAST(smap);
smap->cache_idx = bpf_local_storage_cache_idx_get(&inode_cache);
return &smap->map;
}
static void inode_storage_map_free(struct bpf_map *map)
{
struct bpf_local_storage_map *smap;
smap = (struct bpf_local_storage_map *)map;
bpf_local_storage_cache_idx_free(&inode_cache, smap->cache_idx);
bpf_local_storage_map_free(smap);
}
static int inode_storage_map_btf_id;
const struct bpf_map_ops inode_storage_map_ops = {
.map_alloc_check = bpf_local_storage_map_alloc_check,
.map_alloc = inode_storage_map_alloc,
.map_free = inode_storage_map_free,
.map_get_next_key = notsupp_get_next_key,
.map_lookup_elem = bpf_fd_inode_storage_lookup_elem,
.map_update_elem = bpf_fd_inode_storage_update_elem,
.map_delete_elem = bpf_fd_inode_storage_delete_elem,
.map_check_btf = bpf_local_storage_map_check_btf,
.map_btf_name = "bpf_local_storage_map",
.map_btf_id = &inode_storage_map_btf_id,
.map_owner_storage_ptr = inode_storage_ptr,
};
BTF_ID_LIST(bpf_inode_storage_btf_ids)
BTF_ID_UNUSED
BTF_ID(struct, inode)
const struct bpf_func_proto bpf_inode_storage_get_proto = {
.func = bpf_inode_storage_get,
.gpl_only = false,
.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_PTR_TO_BTF_ID,
.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
.arg4_type = ARG_ANYTHING,
.btf_id = bpf_inode_storage_btf_ids,
};
const struct bpf_func_proto bpf_inode_storage_delete_proto = {
.func = bpf_inode_storage_delete,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_PTR_TO_BTF_ID,
.btf_id = bpf_inode_storage_btf_ids,
};

3
kernel/bpf/syscall.c
View File

@ -769,7 +769,8 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf,
if (map->map_type != BPF_MAP_TYPE_HASH &&
map->map_type != BPF_MAP_TYPE_ARRAY &&
map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
map->map_type != BPF_MAP_TYPE_SK_STORAGE)
map->map_type != BPF_MAP_TYPE_SK_STORAGE &&
map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
return -ENOTSUPP;
if (map->spin_lock_off + sizeof(struct bpf_spin_lock) >
map->value_size) {

10
kernel/bpf/verifier.c
View File

@ -4311,6 +4311,11 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
func_id != BPF_FUNC_sk_storage_delete)
goto error;
break;
case BPF_MAP_TYPE_INODE_STORAGE:
if (func_id != BPF_FUNC_inode_storage_get &&
func_id != BPF_FUNC_inode_storage_delete)
goto error;
break;
default:
break;
}
@ -4384,6 +4389,11 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
goto error;
break;
case BPF_FUNC_inode_storage_get:
case BPF_FUNC_inode_storage_delete:
if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
goto error;
break;
default:
break;
}

6
security/bpf/hooks.c
View File

@ -11,6 +11,7 @@ static struct security_hook_list bpf_lsm_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(NAME, bpf_lsm_##NAME),
#include <linux/lsm_hook_defs.h>
#undef LSM_HOOK
LSM_HOOK_INIT(inode_free_security, bpf_inode_storage_free),
};
static int __init bpf_lsm_init(void)
@ -20,7 +21,12 @@ static int __init bpf_lsm_init(void)
return 0;
}
struct lsm_blob_sizes bpf_lsm_blob_sizes __lsm_ro_after_init = {
.lbs_inode = sizeof(struct bpf_storage_blob),
};
DEFINE_LSM(bpf) = {
.name = "bpf",
.init = bpf_lsm_init,
.blobs = &bpf_lsm_blob_sizes
};

2
tools/bpf/bpftool/Documentation/bpftool-map.rst
View File

@ -49,7 +49,7 @@ MAP COMMANDS
| | **lru_percpu_hash** | **lpm_trie** | **array_of_maps** | **hash_of_maps**
| | **devmap** | **devmap_hash** | **sockmap** | **cpumap** | **xskmap** | **sockhash**
| | **cgroup_storage** | **reuseport_sockarray** | **percpu_cgroup_storage**
| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** }
| | **queue** | **stack** | **sk_storage** | **struct_ops** | **ringbuf** | **inode_storage** }
DESCRIPTION
===========

3
tools/bpf/bpftool/bash-completion/bpftool
View File

@ -704,7 +704,8 @@ _bpftool()
lru_percpu_hash lpm_trie array_of_maps \
hash_of_maps devmap devmap_hash sockmap cpumap \
xskmap sockhash cgroup_storage reuseport_sockarray \
percpu_cgroup_storage queue stack' -- \
percpu_cgroup_storage queue stack sk_storage \
struct_ops inode_storage' -- \
"$cur" ) )
return 0
;;

3
tools/bpf/bpftool/map.c
View File

@ -50,6 +50,7 @@ const char * const map_type_name[] = {
[BPF_MAP_TYPE_SK_STORAGE] = "sk_storage",
[BPF_MAP_TYPE_STRUCT_OPS] = "struct_ops",
[BPF_MAP_TYPE_RINGBUF] = "ringbuf",
[BPF_MAP_TYPE_INODE_STORAGE] = "inode_storage",
};
const size_t map_type_name_size = ARRAY_SIZE(map_type_name);
@ -1442,7 +1443,7 @@ static int do_help(int argc, char **argv)
" lru_percpu_hash | lpm_trie | array_of_maps | hash_of_maps |\n"
" devmap | devmap_hash | sockmap | cpumap | xskmap | sockhash |\n"
" cgroup_storage | reuseport_sockarray | percpu_cgroup_storage |\n"
" queue | stack | sk_storage | struct_ops | ringbuf }\n"
" queue | stack | sk_storage | struct_ops | ringbuf | inode_storage }\n"
" " HELP_SPEC_OPTIONS "\n"
"",
bin_name, argv[-2]);

40
tools/include/uapi/linux/bpf.h
View File

@ -155,6 +155,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_DEVMAP_HASH,
BPF_MAP_TYPE_STRUCT_OPS,
BPF_MAP_TYPE_RINGBUF,
BPF_MAP_TYPE_INODE_STORAGE,
};
/* Note that tracing related programs such as
@ -3509,6 +3510,41 @@ union bpf_attr {
*
* **-EPERM** This helper cannot be used under the
* current sock_ops->op.
* void *bpf_inode_storage_get(struct bpf_map *map, void *inode, void *value, u64 flags)
* Description
* Get a bpf_local_storage from an *inode*.
*
* Logically, it could be thought of as getting the value from
* a *map* with *inode* as the **key**. From this
* perspective, the usage is not much different from
* **bpf_map_lookup_elem**\ (*map*, **&**\ *inode*) except this
* helper enforces the key must be an inode and the map must also
* be a **BPF_MAP_TYPE_INODE_STORAGE**.
*
* Underneath, the value is stored locally at *inode* instead of
* the *map*. The *map* is used as the bpf-local-storage
* "type". The bpf-local-storage "type" (i.e. the *map*) is
* searched against all bpf_local_storage residing at *inode*.
*
* An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be
* used such that a new bpf_local_storage will be
* created if one does not exist. *value* can be used
* together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify
* the initial value of a bpf_local_storage. If *value* is
* **NULL**, the new bpf_local_storage will be zero initialized.
* Return
* A bpf_local_storage pointer is returned on success.
*
* **NULL** if not found or there was an error in adding
* a new bpf_local_storage.
*
* int bpf_inode_storage_delete(struct bpf_map *map, void *inode)
* Description
* Delete a bpf_local_storage from an *inode*.
* Return
* 0 on success.
*
* **-ENOENT** if the bpf_local_storage cannot be found.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -3655,7 +3691,9 @@ union bpf_attr {
FN(get_task_stack), \
FN(load_hdr_opt), \
FN(store_hdr_opt), \
FN(reserve_hdr_opt),
FN(reserve_hdr_opt), \
FN(inode_storage_get), \
FN(inode_storage_delete), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper

5
tools/lib/bpf/libbpf_probes.c
View File

@ -170,7 +170,7 @@ int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
return btf_fd;
}
static int load_sk_storage_btf(void)
static int load_local_storage_btf(void)
{
const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
/* struct bpf_spin_lock {
@ -229,12 +229,13 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
key_size = 0;
break;
case BPF_MAP_TYPE_SK_STORAGE:
case BPF_MAP_TYPE_INODE_STORAGE:
btf_key_type_id = 1;
btf_value_type_id = 3;
value_size = 8;
max_entries = 0;
map_flags = BPF_F_NO_PREALLOC;
btf_fd = load_sk_storage_btf();
btf_fd = load_local_storage_btf();
if (btf_fd < 0)
return false;
break;