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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
225 lines
6.4 KiB
C
225 lines
6.4 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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#include <linux/filter.h>
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#include <linux/bpf.h>
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#include <linux/btf.h>
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#include <linux/binfmts.h>
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#include <linux/lsm_hooks.h>
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#include <linux/bpf_lsm.h>
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#include <linux/kallsyms.h>
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#include <linux/bpf_verifier.h>
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#include <net/bpf_sk_storage.h>
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#include <linux/bpf_local_storage.h>
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#include <linux/btf_ids.h>
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#include <linux/ima.h>
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/* For every LSM hook that allows attachment of BPF programs, declare a nop
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* function where a BPF program can be attached.
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*/
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#define LSM_HOOK(RET, DEFAULT, NAME, ...) \
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noinline RET bpf_lsm_##NAME(__VA_ARGS__) \
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{ \
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return DEFAULT; \
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}
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#include <linux/lsm_hook_defs.h>
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#undef LSM_HOOK
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#define LSM_HOOK(RET, DEFAULT, NAME, ...) BTF_ID(func, bpf_lsm_##NAME)
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BTF_SET_START(bpf_lsm_hooks)
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#include <linux/lsm_hook_defs.h>
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#undef LSM_HOOK
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BTF_SET_END(bpf_lsm_hooks)
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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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{
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if (!prog->gpl_compatible) {
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bpf_log(vlog,
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"LSM programs must have a GPL compatible license\n");
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return -EINVAL;
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}
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if (!btf_id_set_contains(&bpf_lsm_hooks, prog->aux->attach_btf_id)) {
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bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
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prog->aux->attach_btf_id, prog->aux->attach_func_name);
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return -EINVAL;
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}
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return 0;
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}
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/* Mask for all the currently supported BPRM option flags */
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#define BPF_F_BRPM_OPTS_MASK BPF_F_BPRM_SECUREEXEC
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BPF_CALL_2(bpf_bprm_opts_set, struct linux_binprm *, bprm, u64, flags)
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{
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if (flags & ~BPF_F_BRPM_OPTS_MASK)
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return -EINVAL;
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bprm->secureexec = (flags & BPF_F_BPRM_SECUREEXEC);
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return 0;
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}
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BTF_ID_LIST_SINGLE(bpf_bprm_opts_set_btf_ids, struct, linux_binprm)
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const static struct bpf_func_proto bpf_bprm_opts_set_proto = {
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.func = bpf_bprm_opts_set,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_BTF_ID,
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.arg1_btf_id = &bpf_bprm_opts_set_btf_ids[0],
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.arg2_type = ARG_ANYTHING,
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};
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BPF_CALL_3(bpf_ima_inode_hash, struct inode *, inode, void *, dst, u32, size)
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{
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return ima_inode_hash(inode, dst, size);
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}
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static bool bpf_ima_inode_hash_allowed(const struct bpf_prog *prog)
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{
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return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id);
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}
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BTF_ID_LIST_SINGLE(bpf_ima_inode_hash_btf_ids, struct, inode)
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const static struct bpf_func_proto bpf_ima_inode_hash_proto = {
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.func = bpf_ima_inode_hash,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_BTF_ID,
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.arg1_btf_id = &bpf_ima_inode_hash_btf_ids[0],
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.arg2_type = ARG_PTR_TO_UNINIT_MEM,
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.arg3_type = ARG_CONST_SIZE,
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.allowed = bpf_ima_inode_hash_allowed,
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};
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static const struct bpf_func_proto *
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bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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{
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switch (func_id) {
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case BPF_FUNC_inode_storage_get:
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return &bpf_inode_storage_get_proto;
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case BPF_FUNC_inode_storage_delete:
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return &bpf_inode_storage_delete_proto;
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case BPF_FUNC_sk_storage_get:
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return &bpf_sk_storage_get_proto;
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case BPF_FUNC_sk_storage_delete:
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return &bpf_sk_storage_delete_proto;
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case BPF_FUNC_spin_lock:
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return &bpf_spin_lock_proto;
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case BPF_FUNC_spin_unlock:
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return &bpf_spin_unlock_proto;
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case BPF_FUNC_bprm_opts_set:
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return &bpf_bprm_opts_set_proto;
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case BPF_FUNC_ima_inode_hash:
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return prog->aux->sleepable ? &bpf_ima_inode_hash_proto : NULL;
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default:
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return tracing_prog_func_proto(func_id, prog);
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}
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}
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/* The set of hooks which are called without pagefaults disabled and are allowed
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* to "sleep" and thus can be used for sleeable BPF programs.
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*/
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BTF_SET_START(sleepable_lsm_hooks)
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BTF_ID(func, bpf_lsm_bpf)
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BTF_ID(func, bpf_lsm_bpf_map)
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BTF_ID(func, bpf_lsm_bpf_map_alloc_security)
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BTF_ID(func, bpf_lsm_bpf_map_free_security)
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BTF_ID(func, bpf_lsm_bpf_prog)
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BTF_ID(func, bpf_lsm_bprm_check_security)
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BTF_ID(func, bpf_lsm_bprm_committed_creds)
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BTF_ID(func, bpf_lsm_bprm_committing_creds)
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BTF_ID(func, bpf_lsm_bprm_creds_for_exec)
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BTF_ID(func, bpf_lsm_bprm_creds_from_file)
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BTF_ID(func, bpf_lsm_capget)
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BTF_ID(func, bpf_lsm_capset)
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BTF_ID(func, bpf_lsm_cred_prepare)
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BTF_ID(func, bpf_lsm_file_ioctl)
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BTF_ID(func, bpf_lsm_file_lock)
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BTF_ID(func, bpf_lsm_file_open)
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BTF_ID(func, bpf_lsm_file_receive)
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#ifdef CONFIG_SECURITY_NETWORK
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BTF_ID(func, bpf_lsm_inet_conn_established)
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#endif /* CONFIG_SECURITY_NETWORK */
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BTF_ID(func, bpf_lsm_inode_create)
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BTF_ID(func, bpf_lsm_inode_free_security)
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BTF_ID(func, bpf_lsm_inode_getattr)
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BTF_ID(func, bpf_lsm_inode_getxattr)
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BTF_ID(func, bpf_lsm_inode_mknod)
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BTF_ID(func, bpf_lsm_inode_need_killpriv)
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BTF_ID(func, bpf_lsm_inode_post_setxattr)
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BTF_ID(func, bpf_lsm_inode_readlink)
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BTF_ID(func, bpf_lsm_inode_rename)
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BTF_ID(func, bpf_lsm_inode_rmdir)
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BTF_ID(func, bpf_lsm_inode_setattr)
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BTF_ID(func, bpf_lsm_inode_setxattr)
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BTF_ID(func, bpf_lsm_inode_symlink)
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BTF_ID(func, bpf_lsm_inode_unlink)
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BTF_ID(func, bpf_lsm_kernel_module_request)
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BTF_ID(func, bpf_lsm_kernfs_init_security)
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#ifdef CONFIG_KEYS
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BTF_ID(func, bpf_lsm_key_free)
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#endif /* CONFIG_KEYS */
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BTF_ID(func, bpf_lsm_mmap_file)
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BTF_ID(func, bpf_lsm_netlink_send)
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BTF_ID(func, bpf_lsm_path_notify)
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BTF_ID(func, bpf_lsm_release_secctx)
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BTF_ID(func, bpf_lsm_sb_alloc_security)
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BTF_ID(func, bpf_lsm_sb_eat_lsm_opts)
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BTF_ID(func, bpf_lsm_sb_kern_mount)
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BTF_ID(func, bpf_lsm_sb_mount)
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BTF_ID(func, bpf_lsm_sb_remount)
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BTF_ID(func, bpf_lsm_sb_set_mnt_opts)
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BTF_ID(func, bpf_lsm_sb_show_options)
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BTF_ID(func, bpf_lsm_sb_statfs)
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BTF_ID(func, bpf_lsm_sb_umount)
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BTF_ID(func, bpf_lsm_settime)
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#ifdef CONFIG_SECURITY_NETWORK
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BTF_ID(func, bpf_lsm_socket_accept)
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BTF_ID(func, bpf_lsm_socket_bind)
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BTF_ID(func, bpf_lsm_socket_connect)
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BTF_ID(func, bpf_lsm_socket_create)
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BTF_ID(func, bpf_lsm_socket_getpeername)
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BTF_ID(func, bpf_lsm_socket_getpeersec_dgram)
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BTF_ID(func, bpf_lsm_socket_getsockname)
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BTF_ID(func, bpf_lsm_socket_getsockopt)
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BTF_ID(func, bpf_lsm_socket_listen)
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BTF_ID(func, bpf_lsm_socket_post_create)
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BTF_ID(func, bpf_lsm_socket_recvmsg)
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BTF_ID(func, bpf_lsm_socket_sendmsg)
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BTF_ID(func, bpf_lsm_socket_shutdown)
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BTF_ID(func, bpf_lsm_socket_socketpair)
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#endif /* CONFIG_SECURITY_NETWORK */
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BTF_ID(func, bpf_lsm_syslog)
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BTF_ID(func, bpf_lsm_task_alloc)
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BTF_ID(func, bpf_lsm_task_getsecid)
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BTF_ID(func, bpf_lsm_task_prctl)
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BTF_ID(func, bpf_lsm_task_setscheduler)
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BTF_ID(func, bpf_lsm_task_to_inode)
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BTF_SET_END(sleepable_lsm_hooks)
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bool bpf_lsm_is_sleepable_hook(u32 btf_id)
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{
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return btf_id_set_contains(&sleepable_lsm_hooks, btf_id);
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}
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const struct bpf_prog_ops lsm_prog_ops = {
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};
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const struct bpf_verifier_ops lsm_verifier_ops = {
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.get_func_proto = bpf_lsm_func_proto,
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.is_valid_access = btf_ctx_access,
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};
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