lsm_hooks.h

  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 */