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a10787e6d5
To access per-task data, BPF programs usually creates a hash table with
pid as the key. This is not ideal because:
1. The user need to estimate the proper size of the hash table, which may
be inaccurate;
2. Big hash tables are slow;
3. To clean up the data properly during task terminations, the user need
to write extra logic.
Task local storage overcomes these issues and offers a better option for
these per-task data. Task local storage is only available to BPF_LSM. Now
enable it for tracing programs.
Unlike LSM programs, tracing programs can be called in IRQ contexts.
Helpers that access task local storage are updated to use
raw_spin_lock_irqsave() instead of raw_spin_lock_bh().
Tracing programs can attach to functions on the task free path, e.g.
exit_creds(). To avoid allocating task local storage after
bpf_task_storage_free(). bpf_task_storage_get() is updated to not allocate
new storage when the task is not refcounted (task->usage == 0).
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210225234319.336131-2-songliubraving@fb.com
71 lines
1.4 KiB
C
71 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2020 Google LLC.
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*/
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#ifndef _LINUX_BPF_LSM_H
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#define _LINUX_BPF_LSM_H
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#include <linux/sched.h>
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#include <linux/bpf.h>
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#include <linux/lsm_hooks.h>
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#ifdef CONFIG_BPF_LSM
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#define LSM_HOOK(RET, DEFAULT, NAME, ...) \
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RET bpf_lsm_##NAME(__VA_ARGS__);
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#include <linux/lsm_hook_defs.h>
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#undef LSM_HOOK
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struct bpf_storage_blob {
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struct bpf_local_storage __rcu *storage;
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};
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extern struct lsm_blob_sizes bpf_lsm_blob_sizes;
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int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
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const struct bpf_prog *prog);
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bool bpf_lsm_is_sleepable_hook(u32 btf_id);
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static inline struct bpf_storage_blob *bpf_inode(
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const struct inode *inode)
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{
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if (unlikely(!inode->i_security))
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return NULL;
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return inode->i_security + bpf_lsm_blob_sizes.lbs_inode;
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}
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extern const struct bpf_func_proto bpf_inode_storage_get_proto;
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extern const struct bpf_func_proto bpf_inode_storage_delete_proto;
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void bpf_inode_storage_free(struct inode *inode);
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#else /* !CONFIG_BPF_LSM */
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static inline bool bpf_lsm_is_sleepable_hook(u32 btf_id)
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{
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return false;
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}
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static inline int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
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const struct bpf_prog *prog)
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{
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return -EOPNOTSUPP;
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}
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static inline struct bpf_storage_blob *bpf_inode(
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const struct inode *inode)
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{
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return NULL;
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}
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static inline void bpf_inode_storage_free(struct inode *inode)
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{
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}
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#endif /* CONFIG_BPF_LSM */
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#endif /* _LINUX_BPF_LSM_H */
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