1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2008 IBM Corporation
4  *
5  * Authors:
6  * Mimi Zohar <zohar@us.ibm.com>
7  *
8  * File: integrity_iint.c
9  *	- implements the integrity hooks: integrity_inode_alloc,
10  *	  integrity_inode_free
11  *	- cache integrity information associated with an inode
12  *	  using a rbtree tree.
13  */
14 #include <linux/slab.h>
15 #include <linux/init.h>
16 #include <linux/spinlock.h>
17 #include <linux/rbtree.h>
18 #include <linux/file.h>
19 #include <linux/uaccess.h>
20 #include <linux/security.h>
21 #include <linux/lsm_hooks.h>
22 #include "integrity.h"
23 
24 static struct rb_root integrity_iint_tree = RB_ROOT;
25 static DEFINE_RWLOCK(integrity_iint_lock);
26 static struct kmem_cache *iint_cache __read_mostly;
27 
28 struct dentry *integrity_dir;
29 
30 /*
31  * __integrity_iint_find - return the iint associated with an inode
32  */
__integrity_iint_find(struct inode * inode)33 static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
34 {
35 	struct integrity_iint_cache *iint;
36 	struct rb_node *n = integrity_iint_tree.rb_node;
37 
38 	while (n) {
39 		iint = rb_entry(n, struct integrity_iint_cache, rb_node);
40 
41 		if (inode < iint->inode)
42 			n = n->rb_left;
43 		else if (inode > iint->inode)
44 			n = n->rb_right;
45 		else
46 			break;
47 	}
48 	if (!n)
49 		return NULL;
50 
51 	return iint;
52 }
53 
54 /*
55  * integrity_iint_find - return the iint associated with an inode
56  */
integrity_iint_find(struct inode * inode)57 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
58 {
59 	struct integrity_iint_cache *iint;
60 
61 	if (!IS_IMA(inode))
62 		return NULL;
63 
64 	read_lock(&integrity_iint_lock);
65 	iint = __integrity_iint_find(inode);
66 	read_unlock(&integrity_iint_lock);
67 
68 	return iint;
69 }
70 
iint_free(struct integrity_iint_cache * iint)71 static void iint_free(struct integrity_iint_cache *iint)
72 {
73 	kfree(iint->ima_hash);
74 	iint->ima_hash = NULL;
75 	iint->version = 0;
76 	iint->flags = 0UL;
77 	iint->atomic_flags = 0UL;
78 	iint->ima_file_status = INTEGRITY_UNKNOWN;
79 	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
80 	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
81 	iint->ima_read_status = INTEGRITY_UNKNOWN;
82 	iint->ima_creds_status = INTEGRITY_UNKNOWN;
83 	iint->evm_status = INTEGRITY_UNKNOWN;
84 	iint->measured_pcrs = 0;
85 	kmem_cache_free(iint_cache, iint);
86 }
87 
88 /**
89  * integrity_inode_get - find or allocate an iint associated with an inode
90  * @inode: pointer to the inode
91  * @return: allocated iint
92  *
93  * Caller must lock i_mutex
94  */
integrity_inode_get(struct inode * inode)95 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
96 {
97 	struct rb_node **p;
98 	struct rb_node *node, *parent = NULL;
99 	struct integrity_iint_cache *iint, *test_iint;
100 
101 	/*
102 	 * The integrity's "iint_cache" is initialized at security_init(),
103 	 * unless it is not included in the ordered list of LSMs enabled
104 	 * on the boot command line.
105 	 */
106 	if (!iint_cache)
107 		panic("%s: lsm=integrity required.\n", __func__);
108 
109 	iint = integrity_iint_find(inode);
110 	if (iint)
111 		return iint;
112 
113 	iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
114 	if (!iint)
115 		return NULL;
116 
117 	write_lock(&integrity_iint_lock);
118 
119 	p = &integrity_iint_tree.rb_node;
120 	while (*p) {
121 		parent = *p;
122 		test_iint = rb_entry(parent, struct integrity_iint_cache,
123 				     rb_node);
124 		if (inode < test_iint->inode)
125 			p = &(*p)->rb_left;
126 		else
127 			p = &(*p)->rb_right;
128 	}
129 
130 	iint->inode = inode;
131 	node = &iint->rb_node;
132 	inode->i_flags |= S_IMA;
133 	rb_link_node(node, parent, p);
134 	rb_insert_color(node, &integrity_iint_tree);
135 
136 	write_unlock(&integrity_iint_lock);
137 	return iint;
138 }
139 
140 /**
141  * integrity_inode_free - called on security_inode_free
142  * @inode: pointer to the inode
143  *
144  * Free the integrity information(iint) associated with an inode.
145  */
integrity_inode_free(struct inode * inode)146 void integrity_inode_free(struct inode *inode)
147 {
148 	struct integrity_iint_cache *iint;
149 
150 	if (!IS_IMA(inode))
151 		return;
152 
153 	write_lock(&integrity_iint_lock);
154 	iint = __integrity_iint_find(inode);
155 	rb_erase(&iint->rb_node, &integrity_iint_tree);
156 	write_unlock(&integrity_iint_lock);
157 
158 	iint_free(iint);
159 }
160 
init_once(void * foo)161 static void init_once(void *foo)
162 {
163 	struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
164 
165 	memset(iint, 0, sizeof(*iint));
166 	iint->ima_file_status = INTEGRITY_UNKNOWN;
167 	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
168 	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
169 	iint->ima_read_status = INTEGRITY_UNKNOWN;
170 	iint->ima_creds_status = INTEGRITY_UNKNOWN;
171 	iint->evm_status = INTEGRITY_UNKNOWN;
172 	mutex_init(&iint->mutex);
173 }
174 
integrity_iintcache_init(void)175 static int __init integrity_iintcache_init(void)
176 {
177 	iint_cache =
178 	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
179 			      0, SLAB_PANIC, init_once);
180 	return 0;
181 }
182 DEFINE_LSM(integrity) = {
183 	.name = "integrity",
184 	.init = integrity_iintcache_init,
185 };
186 
187 
188 /*
189  * integrity_kernel_read - read data from the file
190  *
191  * This is a function for reading file content instead of kernel_read().
192  * It does not perform locking checks to ensure it cannot be blocked.
193  * It does not perform security checks because it is irrelevant for IMA.
194  *
195  */
integrity_kernel_read(struct file * file,loff_t offset,void * addr,unsigned long count)196 int integrity_kernel_read(struct file *file, loff_t offset,
197 			  void *addr, unsigned long count)
198 {
199 	return __kernel_read(file, addr, count, &offset);
200 }
201 
202 /*
203  * integrity_load_keys - load integrity keys hook
204  *
205  * Hooks is called from init/main.c:kernel_init_freeable()
206  * when rootfs is ready
207  */
integrity_load_keys(void)208 void __init integrity_load_keys(void)
209 {
210 	ima_load_x509();
211 
212 	if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
213 		evm_load_x509();
214 }
215 
integrity_fs_init(void)216 static int __init integrity_fs_init(void)
217 {
218 	integrity_dir = securityfs_create_dir("integrity", NULL);
219 	if (IS_ERR(integrity_dir)) {
220 		int ret = PTR_ERR(integrity_dir);
221 
222 		if (ret != -ENODEV)
223 			pr_err("Unable to create integrity sysfs dir: %d\n",
224 			       ret);
225 		integrity_dir = NULL;
226 		return ret;
227 	}
228 
229 	return 0;
230 }
231 
232 late_initcall(integrity_fs_init)
233