security/apparmor/crypto.c

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor policy loading interface function definitions.
   5  *
   6  * Copyright 2013 Canonical Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation, version 2 of the
  11  * License.
  12  *
  13  * Fns to provide a checksum of policy that has been loaded this can be
  14  * compared to userspace policy compiles to check loaded policy is what
  15  * it should be.
  16  */
  17
  18 #include <crypto/hash.h>
  19
  20 #include "include/apparmor.h"
  21 #include "include/crypto.h"
  22
  23 static unsigned int apparmor_hash_size;
  24
  25 static struct crypto_shash *apparmor_tfm;
  26
  27 unsigned int aa_hash_size(void)
  28 {
  29         return apparmor_hash_size;
  30 }
  31
  32 char *aa_calc_hash(void *data, size_t len)
  33 {
  34         SHASH_DESC_ON_STACK(desc, apparmor_tfm);
  35         char *hash = NULL;
  36         int error = -ENOMEM;
  37
  38         if (!apparmor_tfm)
  39                 return NULL;
  40
  41         hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
  42         if (!hash)
  43                 goto fail;
  44
  45         desc->tfm = apparmor_tfm;
  46         desc->flags = 0;
  47
  48         error = crypto_shash_init(desc);
  49         if (error)
  50                 goto fail;
  51         error = crypto_shash_update(desc, (u8 *) data, len);
  52         if (error)
  53                 goto fail;
  54         error = crypto_shash_final(desc, hash);
  55         if (error)
  56                 goto fail;
  57
  58         return hash;
  59
  60 fail:
  61         kfree(hash);
  62
  63         return ERR_PTR(error);
  64 }
  65
  66 int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
  67                          size_t len)
  68 {
  69         SHASH_DESC_ON_STACK(desc, apparmor_tfm);
  70         int error = -ENOMEM;
  71         __le32 le32_version = cpu_to_le32(version);
  72
  73         if (!aa_g_hash_policy)
  74                 return 0;
  75
  76         if (!apparmor_tfm)
  77                 return 0;
  78
  79         profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
  80         if (!profile->hash)
  81                 goto fail;
  82
  83         desc->tfm = apparmor_tfm;
  84         desc->flags = 0;
  85
  86         error = crypto_shash_init(desc);
  87         if (error)
  88                 goto fail;
  89         error = crypto_shash_update(desc, (u8 *) &le32_version, 4);
  90         if (error)
  91                 goto fail;
  92         error = crypto_shash_update(desc, (u8 *) start, len);
  93         if (error)
  94                 goto fail;
  95         error = crypto_shash_final(desc, profile->hash);
  96         if (error)
  97                 goto fail;
  98
  99         return 0;
 100
 101 fail:
 102         kfree(profile->hash);
 103         profile->hash = NULL;
 104
 105         return error;
 106 }
 107
 108 static int __init init_profile_hash(void)
 109 {
 110         struct crypto_shash *tfm;
 111
 112         if (!apparmor_initialized)
 113                 return 0;
 114
 115         tfm = crypto_alloc_shash("sha1", 0, CRYPTO_ALG_ASYNC);
 116         if (IS_ERR(tfm)) {
 117                 int error = PTR_ERR(tfm);
 118                 AA_ERROR("failed to setup profile sha1 hashing: %d\n", error);
 119                 return error;
 120         }
 121         apparmor_tfm = tfm;
 122         apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm);
 123
 124         aa_info_message("AppArmor sha1 policy hashing enabled");
 125
 126         return 0;
 127 }
 128
 129 late_initcall(init_profile_hash);