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
38 union 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 */
51 struct 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 */
67 struct 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 */
81 struct 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 */
95 struct 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 */
104 struct lsm_blob_sizes {
105 int lbs_cred;
106 int lbs_file;
107 int lbs_ib;
108 int lbs_inode;
109 int lbs_sock;
110 int lbs_superblock;
111 int lbs_ipc;
112 int lbs_key;
113 int lbs_msg_msg;
114 int lbs_perf_event;
115 int lbs_task;
116 int lbs_xattr_count; /* number of xattr slots in new_xattrs array */
117 int lbs_tun_dev;
118 int lbs_bdev;
119 };
120
121 /*
122 * LSM_RET_VOID is used as the default value in LSM_HOOK definitions for void
123 * LSM hooks (in include/linux/lsm_hook_defs.h).
124 */
125 #define LSM_RET_VOID ((void) 0)
126
127 /*
128 * Initializing a security_hook_list structure takes
129 * up a lot of space in a source file. This macro takes
130 * care of the common case and reduces the amount of
131 * text involved.
132 */
133 #define LSM_HOOK_INIT(NAME, HOOK) \
134 { \
135 .scalls = static_calls_table.NAME, \
136 .hook = { .NAME = HOOK } \
137 }
138
139 extern void security_add_hooks(struct security_hook_list *hooks, int count,
140 const struct lsm_id *lsmid);
141
142 #define LSM_FLAG_LEGACY_MAJOR BIT(0)
143 #define LSM_FLAG_EXCLUSIVE BIT(1)
144
145 enum lsm_order {
146 LSM_ORDER_FIRST = -1, /* This is only for capabilities. */
147 LSM_ORDER_MUTABLE = 0,
148 LSM_ORDER_LAST = 1, /* This is only for integrity. */
149 };
150
151 struct lsm_info {
152 const char *name; /* Required. */
153 enum lsm_order order; /* Optional: default is LSM_ORDER_MUTABLE */
154 unsigned long flags; /* Optional: flags describing LSM */
155 int *enabled; /* Optional: controlled by CONFIG_LSM */
156 int (*init)(void); /* Required. */
157 struct lsm_blob_sizes *blobs; /* Optional: for blob sharing. */
158 };
159
160 #define DEFINE_LSM(lsm) \
161 static struct lsm_info __lsm_##lsm \
162 __used __section(".lsm_info.init") \
163 __aligned(sizeof(unsigned long))
164
165 #define DEFINE_EARLY_LSM(lsm) \
166 static struct lsm_info __early_lsm_##lsm \
167 __used __section(".early_lsm_info.init") \
168 __aligned(sizeof(unsigned long))
169
170 /* DO NOT tamper with these variables outside of the LSM framework */
171 extern char *lsm_names;
172 extern struct lsm_static_calls_table static_calls_table __ro_after_init;
173 extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
174 extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];
175
176 /**
177 * lsm_get_xattr_slot - Return the next available slot and increment the index
178 * @xattrs: array storing LSM-provided xattrs
179 * @xattr_count: number of already stored xattrs (updated)
180 *
181 * Retrieve the first available slot in the @xattrs array to fill with an xattr,
182 * and increment @xattr_count.
183 *
184 * Return: The slot to fill in @xattrs if non-NULL, NULL otherwise.
185 */
lsm_get_xattr_slot(struct xattr * xattrs,int * xattr_count)186 static inline struct xattr *lsm_get_xattr_slot(struct xattr *xattrs,
187 int *xattr_count)
188 {
189 if (unlikely(!xattrs))
190 return NULL;
191 return &xattrs[(*xattr_count)++];
192 }
193
194 #endif /* ! __LINUX_LSM_HOOKS_H */
195