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 */ 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 */ 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 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 */ 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 */ 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 } 160 161 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 } 174 175 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 */ 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 */ 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 } 215 216 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