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5d99e198be
A bpf prog returning a positive number attached to file_alloc_security
hook makes kernel panic.
This happens because file system can not filter out the positive number
returned by the LSM prog using IS_ERR, and misinterprets this positive
number as a file pointer.
Given that hook file_alloc_security never returned positive number
before the introduction of BPF LSM, and other BPF LSM hooks may
encounter similar issues, this patch adds LSM return value check
in verifier, to ensure no unexpected value is returned.
Fixes: 520b7aa00d ("bpf: lsm: Initialize the BPF LSM hooks")
Reported-by: Xin Liu <liuxin350@huawei.com>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240719110059.797546-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
452 lines
13 KiB
C
452 lines
13 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 <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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#include <linux/bpf-cgroup.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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BTF_SET_START(bpf_lsm_disabled_hooks)
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BTF_ID(func, bpf_lsm_vm_enough_memory)
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BTF_ID(func, bpf_lsm_inode_need_killpriv)
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BTF_ID(func, bpf_lsm_inode_getsecurity)
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BTF_ID(func, bpf_lsm_inode_listsecurity)
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BTF_ID(func, bpf_lsm_inode_copy_up_xattr)
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BTF_ID(func, bpf_lsm_getselfattr)
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BTF_ID(func, bpf_lsm_getprocattr)
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BTF_ID(func, bpf_lsm_setprocattr)
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#ifdef CONFIG_KEYS
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BTF_ID(func, bpf_lsm_key_getsecurity)
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#endif
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#ifdef CONFIG_AUDIT
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BTF_ID(func, bpf_lsm_audit_rule_match)
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#endif
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BTF_ID(func, bpf_lsm_ismaclabel)
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BTF_SET_END(bpf_lsm_disabled_hooks)
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/* List of LSM hooks that should operate on 'current' cgroup regardless
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* of function signature.
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*/
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BTF_SET_START(bpf_lsm_current_hooks)
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/* operate on freshly allocated sk without any cgroup association */
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#ifdef CONFIG_SECURITY_NETWORK
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BTF_ID(func, bpf_lsm_sk_alloc_security)
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BTF_ID(func, bpf_lsm_sk_free_security)
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#endif
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BTF_SET_END(bpf_lsm_current_hooks)
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/* List of LSM hooks that trigger while the socket is properly locked.
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*/
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BTF_SET_START(bpf_lsm_locked_sockopt_hooks)
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#ifdef CONFIG_SECURITY_NETWORK
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BTF_ID(func, bpf_lsm_sock_graft)
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BTF_ID(func, bpf_lsm_inet_csk_clone)
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BTF_ID(func, bpf_lsm_inet_conn_established)
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#endif
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BTF_SET_END(bpf_lsm_locked_sockopt_hooks)
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/* List of LSM hooks that trigger while the socket is _not_ locked,
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* but it's ok to call bpf_{g,s}etsockopt because the socket is still
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* in the early init phase.
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*/
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BTF_SET_START(bpf_lsm_unlocked_sockopt_hooks)
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#ifdef CONFIG_SECURITY_NETWORK
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BTF_ID(func, bpf_lsm_socket_post_create)
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BTF_ID(func, bpf_lsm_socket_socketpair)
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#endif
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BTF_SET_END(bpf_lsm_unlocked_sockopt_hooks)
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#ifdef CONFIG_CGROUP_BPF
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void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog,
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bpf_func_t *bpf_func)
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{
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const struct btf_param *args __maybe_unused;
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if (btf_type_vlen(prog->aux->attach_func_proto) < 1 ||
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btf_id_set_contains(&bpf_lsm_current_hooks,
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prog->aux->attach_btf_id)) {
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*bpf_func = __cgroup_bpf_run_lsm_current;
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return;
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}
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#ifdef CONFIG_NET
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args = btf_params(prog->aux->attach_func_proto);
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if (args[0].type == btf_sock_ids[BTF_SOCK_TYPE_SOCKET])
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*bpf_func = __cgroup_bpf_run_lsm_socket;
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else if (args[0].type == btf_sock_ids[BTF_SOCK_TYPE_SOCK])
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*bpf_func = __cgroup_bpf_run_lsm_sock;
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else
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#endif
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*bpf_func = __cgroup_bpf_run_lsm_current;
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}
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#endif
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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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u32 btf_id = prog->aux->attach_btf_id;
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const char *func_name = prog->aux->attach_func_name;
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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_disabled_hooks, btf_id)) {
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bpf_log(vlog, "attach_btf_id %u points to disabled hook %s\n",
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btf_id, func_name);
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return -EINVAL;
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}
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if (!btf_id_set_contains(&bpf_lsm_hooks, btf_id)) {
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bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
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btf_id, 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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static const 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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static const 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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.might_sleep = true,
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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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BPF_CALL_3(bpf_ima_file_hash, struct file *, file, void *, dst, u32, size)
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{
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return ima_file_hash(file, dst, size);
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}
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BTF_ID_LIST_SINGLE(bpf_ima_file_hash_btf_ids, struct, file)
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static const struct bpf_func_proto bpf_ima_file_hash_proto = {
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.func = bpf_ima_file_hash,
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.gpl_only = false,
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.might_sleep = true,
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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_file_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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BPF_CALL_1(bpf_get_attach_cookie, void *, ctx)
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{
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struct bpf_trace_run_ctx *run_ctx;
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run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx);
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return run_ctx->bpf_cookie;
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}
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static const struct bpf_func_proto bpf_get_attach_cookie_proto = {
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.func = bpf_get_attach_cookie,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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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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const struct bpf_func_proto *func_proto;
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if (prog->expected_attach_type == BPF_LSM_CGROUP) {
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func_proto = cgroup_common_func_proto(func_id, prog);
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if (func_proto)
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return func_proto;
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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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#ifdef CONFIG_NET
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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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#endif /* CONFIG_NET */
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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 &bpf_ima_inode_hash_proto;
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case BPF_FUNC_ima_file_hash:
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return &bpf_ima_file_hash_proto;
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case BPF_FUNC_get_attach_cookie:
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return bpf_prog_has_trampoline(prog) ? &bpf_get_attach_cookie_proto : NULL;
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#ifdef CONFIG_NET
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case BPF_FUNC_setsockopt:
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if (prog->expected_attach_type != BPF_LSM_CGROUP)
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return NULL;
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if (btf_id_set_contains(&bpf_lsm_locked_sockopt_hooks,
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prog->aux->attach_btf_id))
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return &bpf_sk_setsockopt_proto;
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if (btf_id_set_contains(&bpf_lsm_unlocked_sockopt_hooks,
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prog->aux->attach_btf_id))
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return &bpf_unlocked_sk_setsockopt_proto;
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return NULL;
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case BPF_FUNC_getsockopt:
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if (prog->expected_attach_type != BPF_LSM_CGROUP)
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return NULL;
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if (btf_id_set_contains(&bpf_lsm_locked_sockopt_hooks,
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prog->aux->attach_btf_id))
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return &bpf_sk_getsockopt_proto;
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if (btf_id_set_contains(&bpf_lsm_unlocked_sockopt_hooks,
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prog->aux->attach_btf_id))
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return &bpf_unlocked_sk_getsockopt_proto;
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return NULL;
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#endif
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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 sleepable 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_create)
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BTF_ID(func, bpf_lsm_bpf_map_free)
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BTF_ID(func, bpf_lsm_bpf_prog)
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BTF_ID(func, bpf_lsm_bpf_prog_load)
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BTF_ID(func, bpf_lsm_bpf_prog_free)
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BTF_ID(func, bpf_lsm_bpf_token_create)
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BTF_ID(func, bpf_lsm_bpf_token_free)
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BTF_ID(func, bpf_lsm_bpf_token_cmd)
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BTF_ID(func, bpf_lsm_bpf_token_capable)
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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_post_open)
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BTF_ID(func, bpf_lsm_file_receive)
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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_kernel_read_file)
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BTF_ID(func, bpf_lsm_kernfs_init_security)
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#ifdef CONFIG_SECURITY_PATH
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BTF_ID(func, bpf_lsm_path_unlink)
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BTF_ID(func, bpf_lsm_path_mkdir)
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BTF_ID(func, bpf_lsm_path_rmdir)
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BTF_ID(func, bpf_lsm_path_truncate)
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BTF_ID(func, bpf_lsm_path_symlink)
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BTF_ID(func, bpf_lsm_path_link)
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BTF_ID(func, bpf_lsm_path_rename)
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BTF_ID(func, bpf_lsm_path_chmod)
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BTF_ID(func, bpf_lsm_path_chown)
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#endif /* CONFIG_SECURITY_PATH */
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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_inet_conn_established)
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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_current_getsecid_subj)
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BTF_ID(func, bpf_lsm_task_getsecid_obj)
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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)
|
|
BTF_ID(func, bpf_lsm_userns_create)
|
|
BTF_SET_END(sleepable_lsm_hooks)
|
|
|
|
BTF_SET_START(untrusted_lsm_hooks)
|
|
BTF_ID(func, bpf_lsm_bpf_map_free)
|
|
BTF_ID(func, bpf_lsm_bpf_prog_free)
|
|
BTF_ID(func, bpf_lsm_file_alloc_security)
|
|
BTF_ID(func, bpf_lsm_file_free_security)
|
|
#ifdef CONFIG_SECURITY_NETWORK
|
|
BTF_ID(func, bpf_lsm_sk_alloc_security)
|
|
BTF_ID(func, bpf_lsm_sk_free_security)
|
|
#endif /* CONFIG_SECURITY_NETWORK */
|
|
BTF_ID(func, bpf_lsm_task_free)
|
|
BTF_SET_END(untrusted_lsm_hooks)
|
|
|
|
bool bpf_lsm_is_sleepable_hook(u32 btf_id)
|
|
{
|
|
return btf_id_set_contains(&sleepable_lsm_hooks, btf_id);
|
|
}
|
|
|
|
bool bpf_lsm_is_trusted(const struct bpf_prog *prog)
|
|
{
|
|
return !btf_id_set_contains(&untrusted_lsm_hooks, prog->aux->attach_btf_id);
|
|
}
|
|
|
|
const struct bpf_prog_ops lsm_prog_ops = {
|
|
};
|
|
|
|
const struct bpf_verifier_ops lsm_verifier_ops = {
|
|
.get_func_proto = bpf_lsm_func_proto,
|
|
.is_valid_access = btf_ctx_access,
|
|
};
|
|
|
|
/* hooks return 0 or 1 */
|
|
BTF_SET_START(bool_lsm_hooks)
|
|
#ifdef CONFIG_SECURITY_NETWORK_XFRM
|
|
BTF_ID(func, bpf_lsm_xfrm_state_pol_flow_match)
|
|
#endif
|
|
#ifdef CONFIG_AUDIT
|
|
BTF_ID(func, bpf_lsm_audit_rule_known)
|
|
#endif
|
|
BTF_ID(func, bpf_lsm_inode_xattr_skipcap)
|
|
BTF_SET_END(bool_lsm_hooks)
|
|
|
|
int bpf_lsm_get_retval_range(const struct bpf_prog *prog,
|
|
struct bpf_retval_range *retval_range)
|
|
{
|
|
/* no return value range for void hooks */
|
|
if (!prog->aux->attach_func_proto->type)
|
|
return -EINVAL;
|
|
|
|
if (btf_id_set_contains(&bool_lsm_hooks, prog->aux->attach_btf_id)) {
|
|
retval_range->minval = 0;
|
|
retval_range->maxval = 1;
|
|
} else {
|
|
/* All other available LSM hooks, except task_prctl, return 0
|
|
* on success and negative error code on failure.
|
|
* To keep things simple, we only allow bpf progs to return 0
|
|
* or negative errno for task_prctl too.
|
|
*/
|
|
retval_range->minval = -MAX_ERRNO;
|
|
retval_range->maxval = 0;
|
|
}
|
|
return 0;
|
|
}
|