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linux/security/apparmor/crypto.c
John Johansen f8eb8a1324 apparmor: add the ability to report a sha1 hash of loaded policy
Provide userspace the ability to introspect a sha1 hash value for each
profile currently loaded.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
2013-08-14 11:42:08 -07:00

98 lines
2.0 KiB
C

/*
* AppArmor security module
*
* This file contains AppArmor policy loading interface function definitions.
*
* Copyright 2013 Canonical Ltd.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*
* Fns to provide a checksum of policy that has been loaded this can be
* compared to userspace policy compiles to check loaded policy is what
* it should be.
*/
#include <linux/crypto.h>
#include "include/apparmor.h"
#include "include/crypto.h"
static unsigned int apparmor_hash_size;
static struct crypto_hash *apparmor_tfm;
unsigned int aa_hash_size(void)
{
return apparmor_hash_size;
}
int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
size_t len)
{
struct scatterlist sg[2];
struct hash_desc desc = {
.tfm = apparmor_tfm,
.flags = 0
};
int error = -ENOMEM;
u32 le32_version = cpu_to_le32(version);
if (!apparmor_tfm)
return 0;
sg_init_table(sg, 2);
sg_set_buf(&sg[0], &le32_version, 4);
sg_set_buf(&sg[1], (u8 *) start, len);
profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
if (!profile->hash)
goto fail;
error = crypto_hash_init(&desc);
if (error)
goto fail;
error = crypto_hash_update(&desc, &sg[0], 4);
if (error)
goto fail;
error = crypto_hash_update(&desc, &sg[1], len);
if (error)
goto fail;
error = crypto_hash_final(&desc, profile->hash);
if (error)
goto fail;
return 0;
fail:
kfree(profile->hash);
profile->hash = NULL;
return error;
}
static int __init init_profile_hash(void)
{
struct crypto_hash *tfm;
if (!apparmor_initialized)
return 0;
tfm = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm)) {
int error = PTR_ERR(tfm);
AA_ERROR("failed to setup profile sha1 hashing: %d\n", error);
return error;
}
apparmor_tfm = tfm;
apparmor_hash_size = crypto_hash_digestsize(apparmor_tfm);
aa_info_message("AppArmor sha1 policy hashing enabled");
return 0;
}
late_initcall(init_profile_hash);