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_SPINLOCK(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 assert_spin_locked(&integrity_iint_lock); 39 40 while (n) { 41 iint = rb_entry(n, struct integrity_iint_cache, rb_node); 42 43 if (inode < iint->inode) 44 n = n->rb_left; 45 else if (inode > iint->inode) 46 n = n->rb_right; 47 else 48 break; 49 } 50 if (!n) 51 return NULL; 52 53 return iint; 54 } 55 56 /* 57 * integrity_iint_find - return the iint associated with an inode 58 */ 59 struct integrity_iint_cache *integrity_iint_find(struct inode *inode) 60 { 61 struct integrity_iint_cache *iint; 62 63 if (!IS_IMA(inode)) 64 return NULL; 65 66 spin_lock(&integrity_iint_lock); 67 iint = __integrity_iint_find(inode); 68 spin_unlock(&integrity_iint_lock); 69 70 return iint; 71 } 72 73 static void iint_free(struct integrity_iint_cache *iint) 74 { 75 iint->version = 0; 76 iint->flags = 0UL; 77 iint->evm_status = INTEGRITY_UNKNOWN; 78 kmem_cache_free(iint_cache, iint); 79 } 80 81 /** 82 * integrity_inode_alloc - allocate an iint associated with an inode 83 * @inode: pointer to the inode 84 */ 85 int integrity_inode_alloc(struct inode *inode) 86 { 87 struct rb_node **p; 88 struct rb_node *new_node, *parent = NULL; 89 struct integrity_iint_cache *new_iint, *test_iint; 90 int rc; 91 92 new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 93 if (!new_iint) 94 return -ENOMEM; 95 96 new_iint->inode = inode; 97 new_node = &new_iint->rb_node; 98 99 mutex_lock(&inode->i_mutex); /* i_flags */ 100 spin_lock(&integrity_iint_lock); 101 102 p = &integrity_iint_tree.rb_node; 103 while (*p) { 104 parent = *p; 105 test_iint = rb_entry(parent, struct integrity_iint_cache, 106 rb_node); 107 rc = -EEXIST; 108 if (inode < test_iint->inode) 109 p = &(*p)->rb_left; 110 else if (inode > test_iint->inode) 111 p = &(*p)->rb_right; 112 else 113 goto out_err; 114 } 115 116 inode->i_flags |= S_IMA; 117 rb_link_node(new_node, parent, p); 118 rb_insert_color(new_node, &integrity_iint_tree); 119 120 spin_unlock(&integrity_iint_lock); 121 mutex_unlock(&inode->i_mutex); /* i_flags */ 122 123 return 0; 124 out_err: 125 spin_unlock(&integrity_iint_lock); 126 mutex_unlock(&inode->i_mutex); /* i_flags */ 127 iint_free(new_iint); 128 129 return rc; 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 spin_lock(&integrity_iint_lock); 146 iint = __integrity_iint_find(inode); 147 rb_erase(&iint->rb_node, &integrity_iint_tree); 148 spin_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->version = 0; 159 iint->flags = 0UL; 160 mutex_init(&iint->mutex); 161 iint->evm_status = INTEGRITY_UNKNOWN; 162 } 163 164 static int __init integrity_iintcache_init(void) 165 { 166 iint_cache = 167 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 168 0, SLAB_PANIC, init_once); 169 iint_initialized = 1; 170 return 0; 171 } 172 security_initcall(integrity_iintcache_init); 173