1 /* 2 * Copyright (C) 2008 IBM Corporation 3 * 4 * Authors: 5 * Mimi Zohar <zohar@us.ibm.com> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation, version 2 of the 10 * License. 11 * 12 * File: integrity_iint.c 13 * - implements the integrity hooks: integrity_inode_alloc, 14 * integrity_inode_free 15 * - cache integrity information associated with an inode 16 * using a rbtree tree. 17 */ 18 #include <linux/slab.h> 19 #include <linux/module.h> 20 #include <linux/spinlock.h> 21 #include <linux/rbtree.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 int iint_initialized; 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 iint->version = 0; 74 iint->flags = 0UL; 75 iint->ima_file_status = INTEGRITY_UNKNOWN; 76 iint->ima_mmap_status = INTEGRITY_UNKNOWN; 77 iint->ima_bprm_status = INTEGRITY_UNKNOWN; 78 iint->ima_module_status = INTEGRITY_UNKNOWN; 79 iint->evm_status = INTEGRITY_UNKNOWN; 80 kmem_cache_free(iint_cache, iint); 81 } 82 83 /** 84 * integrity_inode_get - find or allocate an iint associated with an inode 85 * @inode: pointer to the inode 86 * @return: allocated iint 87 * 88 * Caller must lock i_mutex 89 */ 90 struct integrity_iint_cache *integrity_inode_get(struct inode *inode) 91 { 92 struct rb_node **p; 93 struct rb_node *node, *parent = NULL; 94 struct integrity_iint_cache *iint, *test_iint; 95 96 iint = integrity_iint_find(inode); 97 if (iint) 98 return iint; 99 100 iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 101 if (!iint) 102 return NULL; 103 104 write_lock(&integrity_iint_lock); 105 106 p = &integrity_iint_tree.rb_node; 107 while (*p) { 108 parent = *p; 109 test_iint = rb_entry(parent, struct integrity_iint_cache, 110 rb_node); 111 if (inode < test_iint->inode) 112 p = &(*p)->rb_left; 113 else 114 p = &(*p)->rb_right; 115 } 116 117 iint->inode = inode; 118 node = &iint->rb_node; 119 inode->i_flags |= S_IMA; 120 rb_link_node(node, parent, p); 121 rb_insert_color(node, &integrity_iint_tree); 122 123 write_unlock(&integrity_iint_lock); 124 return iint; 125 } 126 127 /** 128 * integrity_inode_free - called on security_inode_free 129 * @inode: pointer to the inode 130 * 131 * Free the integrity information(iint) associated with an inode. 132 */ 133 void integrity_inode_free(struct inode *inode) 134 { 135 struct integrity_iint_cache *iint; 136 137 if (!IS_IMA(inode)) 138 return; 139 140 write_lock(&integrity_iint_lock); 141 iint = __integrity_iint_find(inode); 142 rb_erase(&iint->rb_node, &integrity_iint_tree); 143 write_unlock(&integrity_iint_lock); 144 145 iint_free(iint); 146 } 147 148 static void init_once(void *foo) 149 { 150 struct integrity_iint_cache *iint = foo; 151 152 memset(iint, 0, sizeof *iint); 153 iint->version = 0; 154 iint->flags = 0UL; 155 iint->ima_file_status = INTEGRITY_UNKNOWN; 156 iint->ima_mmap_status = INTEGRITY_UNKNOWN; 157 iint->ima_bprm_status = INTEGRITY_UNKNOWN; 158 iint->ima_module_status = INTEGRITY_UNKNOWN; 159 iint->evm_status = INTEGRITY_UNKNOWN; 160 } 161 162 static int __init integrity_iintcache_init(void) 163 { 164 iint_cache = 165 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 166 0, SLAB_PANIC, init_once); 167 iint_initialized = 1; 168 return 0; 169 } 170 security_initcall(integrity_iintcache_init); 171