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sha1 is insecure and has colisions, thus it is not useful for even lightweight policy hash checks. Switch to sha256, which on modern hardware is fast enough. Separately as per NIST Policy on Hash Functions, sha1 usage must be withdrawn by 2030. This config option currently is one of many that holds up sha1 usage. Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com> Signed-off-by: John Johansen <john.johansen@canonical.com>
124 lines
2.3 KiB
C
124 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* AppArmor security module
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*
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* This file contains AppArmor policy loading interface function definitions.
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*
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* Copyright 2013 Canonical Ltd.
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*
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* Fns to provide a checksum of policy that has been loaded this can be
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* compared to userspace policy compiles to check loaded policy is what
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* it should be.
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*/
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#include <crypto/hash.h>
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#include "include/apparmor.h"
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#include "include/crypto.h"
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static unsigned int apparmor_hash_size;
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static struct crypto_shash *apparmor_tfm;
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unsigned int aa_hash_size(void)
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{
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return apparmor_hash_size;
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}
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char *aa_calc_hash(void *data, size_t len)
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{
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SHASH_DESC_ON_STACK(desc, apparmor_tfm);
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char *hash;
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int error;
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if (!apparmor_tfm)
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return NULL;
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hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
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if (!hash)
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return ERR_PTR(-ENOMEM);
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desc->tfm = apparmor_tfm;
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error = crypto_shash_init(desc);
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if (error)
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goto fail;
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error = crypto_shash_update(desc, (u8 *) data, len);
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if (error)
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goto fail;
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error = crypto_shash_final(desc, hash);
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if (error)
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goto fail;
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return hash;
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fail:
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kfree(hash);
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return ERR_PTR(error);
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}
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int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
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size_t len)
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{
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SHASH_DESC_ON_STACK(desc, apparmor_tfm);
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int error;
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__le32 le32_version = cpu_to_le32(version);
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if (!aa_g_hash_policy)
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return 0;
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if (!apparmor_tfm)
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return 0;
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profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
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if (!profile->hash)
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return -ENOMEM;
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desc->tfm = apparmor_tfm;
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error = crypto_shash_init(desc);
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if (error)
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goto fail;
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error = crypto_shash_update(desc, (u8 *) &le32_version, 4);
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if (error)
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goto fail;
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error = crypto_shash_update(desc, (u8 *) start, len);
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if (error)
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goto fail;
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error = crypto_shash_final(desc, profile->hash);
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if (error)
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goto fail;
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return 0;
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fail:
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kfree(profile->hash);
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profile->hash = NULL;
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return error;
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}
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static int __init init_profile_hash(void)
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{
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struct crypto_shash *tfm;
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if (!apparmor_initialized)
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return 0;
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tfm = crypto_alloc_shash("sha256", 0, 0);
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if (IS_ERR(tfm)) {
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int error = PTR_ERR(tfm);
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AA_ERROR("failed to setup profile sha256 hashing: %d\n", error);
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return error;
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}
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apparmor_tfm = tfm;
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apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm);
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aa_info_message("AppArmor sha256 policy hashing enabled");
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return 0;
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}
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late_initcall(init_profile_hash);
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