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1/*
2 * Linux Security Module interfaces
3 *
4 * Copyright (C) 2001 WireX Communications, Inc <chris@wirex.com>
5 * Copyright (C) 2001 Greg Kroah-Hartman <greg@kroah.com>
6 * Copyright (C) 2001 Networks Associates Technology, Inc <ssmalley@nai.com>
7 * Copyright (C) 2001 James Morris <jmorris@intercode.com.au>
8 * Copyright (C) 2001 Silicon Graphics, Inc. (Trust Technology Group)
9 * Copyright (C) 2015 Intel Corporation.
10 * Copyright (C) 2015 Casey Schaufler <casey@schaufler-ca.com>
11 * Copyright (C) 2016 Mellanox Techonologies
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 *
18 * Due to this file being licensed under the GPL there is controversy over
19 * whether this permits you to write a module that #includes this file
20 * without placing your module under the GPL. Please consult a lawyer for
21 * advice before doing this.
22 *
23 */
24
25#ifndef __LINUX_LSM_HOOKS_H
26#define __LINUX_LSM_HOOKS_H
27
28#include <uapi/linux/lsm.h>
29#include <linux/security.h>
30#include <linux/init.h>
31#include <linux/rculist.h>
32#include <linux/xattr.h>
33#include <linux/static_call.h>
34#include <linux/unroll.h>
35#include <linux/jump_label.h>
36#include <linux/lsm_count.h>
37
38union security_list_options {
39 #define LSM_HOOK(RET, DEFAULT, NAME, ...) RET (*NAME)(__VA_ARGS__);
40 #include "lsm_hook_defs.h"
41 #undef LSM_HOOK
42 void *lsm_func_addr;
43};
44
45/*
46 * @key: static call key as defined by STATIC_CALL_KEY
47 * @trampoline: static call trampoline as defined by STATIC_CALL_TRAMP
48 * @hl: The security_hook_list as initialized by the owning LSM.
49 * @active: Enabled when the static call has an LSM hook associated.
50 */
51struct lsm_static_call {
52 struct static_call_key *key;
53 void *trampoline;
54 struct security_hook_list *hl;
55 /* this needs to be true or false based on what the key defaults to */
56 struct static_key_false *active;
57} __randomize_layout;
58
59/*
60 * Table of the static calls for each LSM hook.
61 * Once the LSMs are initialized, their callbacks will be copied to these
62 * tables such that the calls are filled backwards (from last to first).
63 * This way, we can jump directly to the first used static call, and execute
64 * all of them after. This essentially makes the entry point
65 * dynamic to adapt the number of static calls to the number of callbacks.
66 */
67struct lsm_static_calls_table {
68 #define LSM_HOOK(RET, DEFAULT, NAME, ...) \
69 struct lsm_static_call NAME[MAX_LSM_COUNT];
70 #include <linux/lsm_hook_defs.h>
71 #undef LSM_HOOK
72} __packed __randomize_layout;
73
74/**
75 * struct lsm_id - Identify a Linux Security Module.
76 * @lsm: name of the LSM, must be approved by the LSM maintainers
77 * @id: LSM ID number from uapi/linux/lsm.h
78 *
79 * Contains the information that identifies the LSM.
80 */
81struct lsm_id {
82 const char *name;
83 u64 id;
84};
85
86/*
87 * Security module hook list structure.
88 * For use with generic list macros for common operations.
89 *
90 * struct security_hook_list - Contents of a cacheable, mappable object.
91 * @scalls: The beginning of the array of static calls assigned to this hook.
92 * @hook: The callback for the hook.
93 * @lsm: The name of the lsm that owns this hook.
94 */
95struct security_hook_list {
96 struct lsm_static_call *scalls;
97 union security_list_options hook;
98 const struct lsm_id *lsmid;
99} __randomize_layout;
100
101/*
102 * Security blob size or offset data.
103 */
104struct lsm_blob_sizes {
105 unsigned int lbs_cred;
106 unsigned int lbs_file;
107 unsigned int lbs_ib;
108 unsigned int lbs_inode;
109 unsigned int lbs_sock;
110 unsigned int lbs_superblock;
111 unsigned int lbs_ipc;
112 unsigned int lbs_key;
113 unsigned int lbs_msg_msg;
114 unsigned int lbs_perf_event;
115 unsigned int lbs_task;
116 unsigned int lbs_xattr_count; /* num xattr slots in new_xattrs array */
117 unsigned int lbs_tun_dev;
118 unsigned int lbs_bdev;
119 unsigned int lbs_bpf_map;
120 unsigned int lbs_bpf_prog;
121 unsigned int lbs_bpf_token;
122};
123
124/*
125 * LSM_RET_VOID is used as the default value in LSM_HOOK definitions for void
126 * LSM hooks (in include/linux/lsm_hook_defs.h).
127 */
128#define LSM_RET_VOID ((void) 0)
129
130/*
131 * Initializing a security_hook_list structure takes
132 * up a lot of space in a source file. This macro takes
133 * care of the common case and reduces the amount of
134 * text involved.
135 */
136#define LSM_HOOK_INIT(NAME, HOOK) \
137 { \
138 .scalls = static_calls_table.NAME, \
139 .hook = { .NAME = HOOK } \
140 }
141
142extern void security_add_hooks(struct security_hook_list *hooks, int count,
143 const struct lsm_id *lsmid);
144
145#define LSM_FLAG_LEGACY_MAJOR BIT(0)
146#define LSM_FLAG_EXCLUSIVE BIT(1)
147
148enum lsm_order {
149 LSM_ORDER_FIRST = -1, /* This is only for capabilities. */
150 LSM_ORDER_MUTABLE = 0,
151 LSM_ORDER_LAST = 1, /* This is only for integrity. */
152};
153
154/**
155 * struct lsm_info - Define an individual LSM for the LSM framework.
156 * @id: LSM name/ID info
157 * @order: ordering with respect to other LSMs, optional
158 * @flags: descriptive flags, optional
159 * @blobs: LSM blob sharing, optional
160 * @enabled: controlled by CONFIG_LSM, optional
161 * @init: LSM specific initialization routine
162 * @initcall_pure: LSM callback for initcall_pure() setup, optional
163 * @initcall_early: LSM callback for early_initcall setup, optional
164 * @initcall_core: LSM callback for core_initcall() setup, optional
165 * @initcall_subsys: LSM callback for subsys_initcall() setup, optional
166 * @initcall_fs: LSM callback for fs_initcall setup, optional
167 * @nitcall_device: LSM callback for device_initcall() setup, optional
168 * @initcall_late: LSM callback for late_initcall() setup, optional
169 */
170struct lsm_info {
171 const struct lsm_id *id;
172 enum lsm_order order;
173 unsigned long flags;
174 struct lsm_blob_sizes *blobs;
175 int *enabled;
176 int (*init)(void);
177 int (*initcall_pure)(void);
178 int (*initcall_early)(void);
179 int (*initcall_core)(void);
180 int (*initcall_subsys)(void);
181 int (*initcall_fs)(void);
182 int (*initcall_device)(void);
183 int (*initcall_late)(void);
184};
185
186#define DEFINE_LSM(lsm) \
187 static struct lsm_info __lsm_##lsm \
188 __used __section(".lsm_info.init") \
189 __aligned(sizeof(unsigned long))
190
191#define DEFINE_EARLY_LSM(lsm) \
192 static struct lsm_info __early_lsm_##lsm \
193 __used __section(".early_lsm_info.init") \
194 __aligned(sizeof(unsigned long))
195
196
197/* DO NOT tamper with these variables outside of the LSM framework */
198extern struct lsm_static_calls_table static_calls_table __ro_after_init;
199
200/**
201 * lsm_get_xattr_slot - Return the next available slot and increment the index
202 * @xattrs: array storing LSM-provided xattrs
203 * @xattr_count: number of already stored xattrs (updated)
204 *
205 * Retrieve the first available slot in the @xattrs array to fill with an xattr,
206 * and increment @xattr_count.
207 *
208 * Return: The slot to fill in @xattrs if non-NULL, NULL otherwise.
209 */
210static inline struct xattr *lsm_get_xattr_slot(struct xattr *xattrs,
211 int *xattr_count)
212{
213 if (unlikely(!xattrs))
214 return NULL;
215 return &xattrs[(*xattr_count)++];
216}
217
218#endif /* ! __LINUX_LSM_HOOKS_H */
219

source code of linux/include/linux/lsm_hooks.h