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_status = INTEGRITY_UNKNOWN; 76 iint->evm_status = INTEGRITY_UNKNOWN; 77 kmem_cache_free(iint_cache, iint); 78 } 79 80 /** 81 * integrity_inode_get - find or allocate an iint associated with an inode 82 * @inode: pointer to the inode 83 * @return: allocated iint 84 * 85 * Caller must lock i_mutex 86 */ 87 struct integrity_iint_cache *integrity_inode_get(struct inode *inode) 88 { 89 struct rb_node **p; 90 struct rb_node *node, *parent = NULL; 91 struct integrity_iint_cache *iint, *test_iint; 92 93 iint = integrity_iint_find(inode); 94 if (iint) 95 return iint; 96 97 iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 98 if (!iint) 99 return NULL; 100 101 write_lock(&integrity_iint_lock); 102 103 p = &integrity_iint_tree.rb_node; 104 while (*p) { 105 parent = *p; 106 test_iint = rb_entry(parent, struct integrity_iint_cache, 107 rb_node); 108 if (inode < test_iint->inode) 109 p = &(*p)->rb_left; 110 else 111 p = &(*p)->rb_right; 112 } 113 114 iint->inode = inode; 115 node = &iint->rb_node; 116 inode->i_flags |= S_IMA; 117 rb_link_node(node, parent, p); 118 rb_insert_color(node, &integrity_iint_tree); 119 120 write_unlock(&integrity_iint_lock); 121 return iint; 122 } 123 124 /** 125 * integrity_inode_free - called on security_inode_free 126 * @inode: pointer to the inode 127 * 128 * Free the integrity information(iint) associated with an inode. 129 */ 130 void integrity_inode_free(struct inode *inode) 131 { 132 struct integrity_iint_cache *iint; 133 134 if (!IS_IMA(inode)) 135 return; 136 137 write_lock(&integrity_iint_lock); 138 iint = __integrity_iint_find(inode); 139 rb_erase(&iint->rb_node, &integrity_iint_tree); 140 write_unlock(&integrity_iint_lock); 141 142 iint_free(iint); 143 } 144 145 static void init_once(void *foo) 146 { 147 struct integrity_iint_cache *iint = foo; 148 149 memset(iint, 0, sizeof *iint); 150 iint->version = 0; 151 iint->flags = 0UL; 152 iint->ima_status = INTEGRITY_UNKNOWN; 153 iint->evm_status = INTEGRITY_UNKNOWN; 154 } 155 156 static int __init integrity_iintcache_init(void) 157 { 158 iint_cache = 159 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 160 0, SLAB_PANIC, init_once); 161 iint_initialized = 1; 162 return 0; 163 } 164 security_initcall(integrity_iintcache_init); 165