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 iint = integrity_iint_find(inode); 102 if (iint) 103 return iint; 104 105 iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 106 if (!iint) 107 return NULL; 108 109 write_lock(&integrity_iint_lock); 110 111 p = &integrity_iint_tree.rb_node; 112 while (*p) { 113 parent = *p; 114 test_iint = rb_entry(parent, struct integrity_iint_cache, 115 rb_node); 116 if (inode < test_iint->inode) 117 p = &(*p)->rb_left; 118 else 119 p = &(*p)->rb_right; 120 } 121 122 iint->inode = inode; 123 node = &iint->rb_node; 124 inode->i_flags |= S_IMA; 125 rb_link_node(node, parent, p); 126 rb_insert_color(node, &integrity_iint_tree); 127 128 write_unlock(&integrity_iint_lock); 129 return iint; 130 } 131 132 /** 133 * integrity_inode_free - called on security_inode_free 134 * @inode: pointer to the inode 135 * 136 * Free the integrity information(iint) associated with an inode. 137 */ 138 void integrity_inode_free(struct inode *inode) 139 { 140 struct integrity_iint_cache *iint; 141 142 if (!IS_IMA(inode)) 143 return; 144 145 write_lock(&integrity_iint_lock); 146 iint = __integrity_iint_find(inode); 147 rb_erase(&iint->rb_node, &integrity_iint_tree); 148 write_unlock(&integrity_iint_lock); 149 150 iint_free(iint); 151 } 152 153 static void init_once(void *foo) 154 { 155 struct integrity_iint_cache *iint = foo; 156 157 memset(iint, 0, sizeof(*iint)); 158 iint->ima_file_status = INTEGRITY_UNKNOWN; 159 iint->ima_mmap_status = INTEGRITY_UNKNOWN; 160 iint->ima_bprm_status = INTEGRITY_UNKNOWN; 161 iint->ima_read_status = INTEGRITY_UNKNOWN; 162 iint->ima_creds_status = INTEGRITY_UNKNOWN; 163 iint->evm_status = INTEGRITY_UNKNOWN; 164 mutex_init(&iint->mutex); 165 } 166 167 static int __init integrity_iintcache_init(void) 168 { 169 iint_cache = 170 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 171 0, SLAB_PANIC, init_once); 172 return 0; 173 } 174 DEFINE_LSM(integrity) = { 175 .name = "integrity", 176 .init = integrity_iintcache_init, 177 }; 178 179 180 /* 181 * integrity_kernel_read - read data from the file 182 * 183 * This is a function for reading file content instead of kernel_read(). 184 * It does not perform locking checks to ensure it cannot be blocked. 185 * It does not perform security checks because it is irrelevant for IMA. 186 * 187 */ 188 int integrity_kernel_read(struct file *file, loff_t offset, 189 void *addr, unsigned long count) 190 { 191 mm_segment_t old_fs; 192 char __user *buf = (char __user *)addr; 193 ssize_t ret; 194 195 if (!(file->f_mode & FMODE_READ)) 196 return -EBADF; 197 198 old_fs = get_fs(); 199 set_fs(KERNEL_DS); 200 ret = __vfs_read(file, buf, count, &offset); 201 set_fs(old_fs); 202 203 return ret; 204 } 205 206 /* 207 * integrity_load_keys - load integrity keys hook 208 * 209 * Hooks is called from init/main.c:kernel_init_freeable() 210 * when rootfs is ready 211 */ 212 void __init integrity_load_keys(void) 213 { 214 ima_load_x509(); 215 evm_load_x509(); 216 } 217 218 static int __init integrity_fs_init(void) 219 { 220 integrity_dir = securityfs_create_dir("integrity", NULL); 221 if (IS_ERR(integrity_dir)) { 222 int ret = PTR_ERR(integrity_dir); 223 224 if (ret != -ENODEV) 225 pr_err("Unable to create integrity sysfs dir: %d\n", 226 ret); 227 integrity_dir = NULL; 228 return ret; 229 } 230 231 return 0; 232 } 233 234 late_initcall(integrity_fs_init) 235