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 struct { 35 struct shash_desc shash; 36 char ctx[crypto_shash_descsize(apparmor_tfm)]; 37 } desc; 38 char *hash = NULL; 39 int error = -ENOMEM; 40 41 if (!apparmor_tfm) 42 return NULL; 43 44 hash = kzalloc(apparmor_hash_size, GFP_KERNEL); 45 if (!hash) 46 goto fail; 47 48 desc.shash.tfm = apparmor_tfm; 49 desc.shash.flags = 0; 50 51 error = crypto_shash_init(&desc.shash); 52 if (error) 53 goto fail; 54 error = crypto_shash_update(&desc.shash, (u8 *) data, len); 55 if (error) 56 goto fail; 57 error = crypto_shash_final(&desc.shash, hash); 58 if (error) 59 goto fail; 60 61 return hash; 62 63 fail: 64 kfree(hash); 65 66 return ERR_PTR(error); 67 } 68 69 int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start, 70 size_t len) 71 { 72 struct { 73 struct shash_desc shash; 74 char ctx[crypto_shash_descsize(apparmor_tfm)]; 75 } desc; 76 int error = -ENOMEM; 77 __le32 le32_version = cpu_to_le32(version); 78 79 if (!aa_g_hash_policy) 80 return 0; 81 82 if (!apparmor_tfm) 83 return 0; 84 85 profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL); 86 if (!profile->hash) 87 goto fail; 88 89 desc.shash.tfm = apparmor_tfm; 90 desc.shash.flags = 0; 91 92 error = crypto_shash_init(&desc.shash); 93 if (error) 94 goto fail; 95 error = crypto_shash_update(&desc.shash, (u8 *) &le32_version, 4); 96 if (error) 97 goto fail; 98 error = crypto_shash_update(&desc.shash, (u8 *) start, len); 99 if (error) 100 goto fail; 101 error = crypto_shash_final(&desc.shash, profile->hash); 102 if (error) 103 goto fail; 104 105 return 0; 106 107 fail: 108 kfree(profile->hash); 109 profile->hash = NULL; 110 111 return error; 112 } 113 114 static int __init init_profile_hash(void) 115 { 116 struct crypto_shash *tfm; 117 118 if (!apparmor_initialized) 119 return 0; 120 121 tfm = crypto_alloc_shash("sha1", 0, CRYPTO_ALG_ASYNC); 122 if (IS_ERR(tfm)) { 123 int error = PTR_ERR(tfm); 124 AA_ERROR("failed to setup profile sha1 hashing: %d\n", error); 125 return error; 126 } 127 apparmor_tfm = tfm; 128 apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm); 129 130 aa_info_message("AppArmor sha1 policy hashing enabled"); 131 132 return 0; 133 } 134 135 late_initcall(init_profile_hash); 136