bpf: Implement task local storage

Similar to bpf_local_storage for sockets and inodes add local storage
for task_struct.

The life-cycle of storage is managed with the life-cycle of the
task_struct.  i.e. the storage is destroyed along with the owning task
with a callback to the bpf_task_storage_free from the task_free LSM
hook.

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.

The userspace map operations can be done by using a pid fd as a key
passed to the lookup, update and delete operations.

Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201106103747.2780972-3-kpsingh@chromium.org
This commit is contained in:
KP Singh
2020-11-06 10:37:40 +00:00
committed by Alexei Starovoitov
parent 9e7a4d9831
commit 4cf1bc1f10
10 changed files with 436 additions and 1 deletions

View File

@@ -7,6 +7,7 @@
#ifndef _LINUX_BPF_LSM_H
#define _LINUX_BPF_LSM_H
#include <linux/sched.h>
#include <linux/bpf.h>
#include <linux/lsm_hooks.h>
@@ -35,9 +36,21 @@ static inline struct bpf_storage_blob *bpf_inode(
return inode->i_security + bpf_lsm_blob_sizes.lbs_inode;
}
static inline struct bpf_storage_blob *bpf_task(
const struct task_struct *task)
{
if (unlikely(!task->security))
return NULL;
return task->security + bpf_lsm_blob_sizes.lbs_task;
}
extern const struct bpf_func_proto bpf_inode_storage_get_proto;
extern const struct bpf_func_proto bpf_inode_storage_delete_proto;
extern const struct bpf_func_proto bpf_task_storage_get_proto;
extern const struct bpf_func_proto bpf_task_storage_delete_proto;
void bpf_inode_storage_free(struct inode *inode);
void bpf_task_storage_free(struct task_struct *task);
#else /* !CONFIG_BPF_LSM */
@@ -53,10 +66,20 @@ static inline struct bpf_storage_blob *bpf_inode(
return NULL;
}
static inline struct bpf_storage_blob *bpf_task(
const struct task_struct *task)
{
return NULL;
}
static inline void bpf_inode_storage_free(struct inode *inode)
{
}
static inline void bpf_task_storage_free(struct task_struct *task)
{
}
#endif /* CONFIG_BPF_LSM */
#endif /* _LINUX_BPF_LSM_H */