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bpf: Implement bpf_local_storage for inodes

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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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40
include/uapi/linux/bpf.h
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@@ -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