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https://github.com/torvalds/linux
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27672f0d28
Provide a wrapper function to get the IMA hash of an inode. This helper is useful in fingerprinting files (e.g executables on execution) and using these fingerprints in detections like an executable unlinking itself. Since the ima_inode_hash can sleep, it's only allowed for sleepable LSM hooks. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20201124151210.1081188-3-kpsingh@chromium.org
218 lines
6.4 KiB
C
218 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_task_storage_get:
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return &bpf_task_storage_get_proto;
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case BPF_FUNC_task_storage_delete:
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return &bpf_task_storage_delete_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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BTF_ID(func, bpf_lsm_inet_conn_established)
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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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BTF_ID(func, bpf_lsm_key_free)
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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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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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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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