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
 19static unsigned int apparmor_hash_size;
 20
 21static struct crypto_shash *apparmor_tfm;
 22
 23unsigned int aa_hash_size(void)
 24{
 25	return apparmor_hash_size;
 26}
 27
 28char *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
 55fail:
 56	kfree(hash);
 57
 58	return ERR_PTR(error);
 59}
 60
 61int 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
 95fail:
 96	kfree(profile->hash);
 97	profile->hash = NULL;
 98
 99	return error;
100}
101
102static 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
123late_initcall(init_profile_hash);