1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AppArmor security module 4 * 5 * This file contains AppArmor policy loading interface function definitions. 6 * 7 * Copyright 2013 Canonical Ltd. 8 * 9 * Fns to provide a checksum of policy that has been loaded this can be 10 * compared to userspace policy compiles to check loaded policy is what 11 * it should be. 12 */ 13 14 #include <crypto/hash.h> 15 16 #include "include/apparmor.h" 17 #include "include/crypto.h" 18 19 static unsigned int apparmor_hash_size; 20 21 static struct crypto_shash *apparmor_tfm; 22 23 unsigned int aa_hash_size(void) 24 { 25 return apparmor_hash_size; 26 } 27 28 char *aa_calc_hash(void *data, size_t len) 29 { 30 SHASH_DESC_ON_STACK(desc, apparmor_tfm); 31 char *hash; 32 int error; 33 34 if (!apparmor_tfm) 35 return NULL; 36 37 hash = kzalloc(apparmor_hash_size, GFP_KERNEL); 38 if (!hash) 39 return ERR_PTR(-ENOMEM); 40 41 desc->tfm = apparmor_tfm; 42 43 error = crypto_shash_init(desc); 44 if (error) 45 goto fail; 46 error = crypto_shash_update(desc, (u8 *) data, len); 47 if (error) 48 goto fail; 49 error = crypto_shash_final(desc, hash); 50 if (error) 51 goto fail; 52 53 return hash; 54 55 fail: 56 kfree(hash); 57 58 return ERR_PTR(error); 59 } 60 61 int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start, 62 size_t len) 63 { 64 SHASH_DESC_ON_STACK(desc, apparmor_tfm); 65 int error; 66 __le32 le32_version = cpu_to_le32(version); 67 68 if (!aa_g_hash_policy) 69 return 0; 70 71 if (!apparmor_tfm) 72 return 0; 73 74 profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL); 75 if (!profile->hash) 76 return -ENOMEM; 77 78 desc->tfm = apparmor_tfm; 79 80 error = crypto_shash_init(desc); 81 if (error) 82 goto fail; 83 error = crypto_shash_update(desc, (u8 *) &le32_version, 4); 84 if (error) 85 goto fail; 86 error = crypto_shash_update(desc, (u8 *) start, len); 87 if (error) 88 goto fail; 89 error = crypto_shash_final(desc, profile->hash); 90 if (error) 91 goto fail; 92 93 return 0; 94 95 fail: 96 kfree(profile->hash); 97 profile->hash = NULL; 98 99 return error; 100 } 101 102 static int __init init_profile_hash(void) 103 { 104 struct crypto_shash *tfm; 105 106 if (!apparmor_initialized) 107 return 0; 108 109 tfm = crypto_alloc_shash("sha256", 0, 0); 110 if (IS_ERR(tfm)) { 111 int error = PTR_ERR(tfm); 112 AA_ERROR("failed to setup profile sha256 hashing: %d\n", error); 113 return error; 114 } 115 apparmor_tfm = tfm; 116 apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm); 117 118 aa_info_message("AppArmor sha256 policy hashing enabled"); 119 120 return 0; 121 } 122 123 late_initcall(init_profile_hash); 124