Mimi Zohar | f381c27 | 2011-03-09 14:13:22 -0500 | [diff] [blame^] | 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 | kmem_cache_free(iint_cache, iint); |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * integrity_inode_alloc - allocate an iint associated with an inode |
| 82 | * @inode: pointer to the inode |
| 83 | */ |
| 84 | int integrity_inode_alloc(struct inode *inode) |
| 85 | { |
| 86 | struct rb_node **p; |
| 87 | struct rb_node *new_node, *parent = NULL; |
| 88 | struct integrity_iint_cache *new_iint, *test_iint; |
| 89 | int rc; |
| 90 | |
| 91 | new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS); |
| 92 | if (!new_iint) |
| 93 | return -ENOMEM; |
| 94 | |
| 95 | new_iint->inode = inode; |
| 96 | new_node = &new_iint->rb_node; |
| 97 | |
| 98 | mutex_lock(&inode->i_mutex); /* i_flags */ |
| 99 | spin_lock(&integrity_iint_lock); |
| 100 | |
| 101 | p = &integrity_iint_tree.rb_node; |
| 102 | while (*p) { |
| 103 | parent = *p; |
| 104 | test_iint = rb_entry(parent, struct integrity_iint_cache, |
| 105 | rb_node); |
| 106 | rc = -EEXIST; |
| 107 | if (inode < test_iint->inode) |
| 108 | p = &(*p)->rb_left; |
| 109 | else if (inode > test_iint->inode) |
| 110 | p = &(*p)->rb_right; |
| 111 | else |
| 112 | goto out_err; |
| 113 | } |
| 114 | |
| 115 | inode->i_flags |= S_IMA; |
| 116 | rb_link_node(new_node, parent, p); |
| 117 | rb_insert_color(new_node, &integrity_iint_tree); |
| 118 | |
| 119 | spin_unlock(&integrity_iint_lock); |
| 120 | mutex_unlock(&inode->i_mutex); /* i_flags */ |
| 121 | |
| 122 | return 0; |
| 123 | out_err: |
| 124 | spin_unlock(&integrity_iint_lock); |
| 125 | mutex_unlock(&inode->i_mutex); /* i_flags */ |
| 126 | iint_free(new_iint); |
| 127 | |
| 128 | return rc; |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * integrity_inode_free - called on security_inode_free |
| 133 | * @inode: pointer to the inode |
| 134 | * |
| 135 | * Free the integrity information(iint) associated with an inode. |
| 136 | */ |
| 137 | void integrity_inode_free(struct inode *inode) |
| 138 | { |
| 139 | struct integrity_iint_cache *iint; |
| 140 | |
| 141 | if (!IS_IMA(inode)) |
| 142 | return; |
| 143 | |
| 144 | spin_lock(&integrity_iint_lock); |
| 145 | iint = __integrity_iint_find(inode); |
| 146 | rb_erase(&iint->rb_node, &integrity_iint_tree); |
| 147 | spin_unlock(&integrity_iint_lock); |
| 148 | |
| 149 | iint_free(iint); |
| 150 | } |
| 151 | |
| 152 | static void init_once(void *foo) |
| 153 | { |
| 154 | struct integrity_iint_cache *iint = foo; |
| 155 | |
| 156 | memset(iint, 0, sizeof *iint); |
| 157 | iint->version = 0; |
| 158 | iint->flags = 0UL; |
| 159 | mutex_init(&iint->mutex); |
| 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); |