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apparmor: use SHA-256 library API instead of crypto_shash API

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This user of SHA-256 does not support any other algorithm, so the
crypto_shash abstraction provides no value.  Just use the SHA-256
library API instead, which is much simpler and easier to use.

Acked-by: John Johansen <john.johansen@canonical.com>
Link: https://lore.kernel.org/r/20250630174805.59010-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers 2025-06-30 10:48:05 -07:00
parent c76ed8790b
commit f93c27092a
2 changed files with 13 additions and 75 deletions
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3
security/apparmor/Kconfig
View file

@ -59,8 +59,7 @@ config SECURITY_APPARMOR_INTROSPECT_POLICY
config SECURITY_APPARMOR_HASH
bool "Enable introspection of sha256 hashes for loaded profiles"
depends on SECURITY_APPARMOR_INTROSPECT_POLICY
select CRYPTO
select CRYPTO_SHA256
select CRYPTO_LIB_SHA256
default y
help
This option selects whether introspection of loaded policy

85
security/apparmor/crypto.c
View file

@ -11,113 +11,52 @@
* it should be.
*/
#include <crypto/hash.h>
#include <crypto/sha2.h>
#include "include/apparmor.h"
#include "include/crypto.h"
static unsigned int apparmor_hash_size;
static struct crypto_shash *apparmor_tfm;
unsigned int aa_hash_size(void)
{
return apparmor_hash_size;
return SHA256_DIGEST_SIZE;
}
char *aa_calc_hash(void *data, size_t len)
{
SHASH_DESC_ON_STACK(desc, apparmor_tfm);
char *hash;
int error;
if (!apparmor_tfm)
return NULL;
hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
hash = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
if (!hash)
return ERR_PTR(-ENOMEM);
desc->tfm = apparmor_tfm;
error = crypto_shash_init(desc);
if (error)
goto fail;
error = crypto_shash_update(desc, (u8 *) data, len);
if (error)
goto fail;
error = crypto_shash_final(desc, hash);
if (error)
goto fail;
sha256(data, len, hash);
return hash;
fail:
kfree(hash);
return ERR_PTR(error);
}
int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
size_t len)
{
SHASH_DESC_ON_STACK(desc, apparmor_tfm);
int error;
struct sha256_ctx sctx;
__le32 le32_version = cpu_to_le32(version);
if (!aa_g_hash_policy)
return 0;
if (!apparmor_tfm)
return 0;
profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
profile->hash = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
if (!profile->hash)
return -ENOMEM;
desc->tfm = apparmor_tfm;
error = crypto_shash_init(desc);
if (error)
goto fail;
error = crypto_shash_update(desc, (u8 *) &le32_version, 4);
if (error)
goto fail;
error = crypto_shash_update(desc, (u8 *) start, len);
if (error)
goto fail;
error = crypto_shash_final(desc, profile->hash);
if (error)
goto fail;
sha256_init(&sctx);
sha256_update(&sctx, (u8 *)&le32_version, 4);
sha256_update(&sctx, (u8 *)start, len);
sha256_final(&sctx, profile->hash);
return 0;
fail:
kfree(profile->hash);
profile->hash = NULL;
return error;
}
static int __init init_profile_hash(void)
{
struct crypto_shash *tfm;
if (!apparmor_initialized)
return 0;
tfm = crypto_alloc_shash("sha256", 0, 0);
if (IS_ERR(tfm)) {
int error = PTR_ERR(tfm);
AA_ERROR("failed to setup profile sha256 hashing: %d\n", error);
return error;
}
apparmor_tfm = tfm;
apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm);
aa_info_message("AppArmor sha256 policy hashing enabled");
if (apparmor_initialized)
aa_info_message("AppArmor sha256 policy hashing enabled");
return 0;
}
late_initcall(init_profile_hash);