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

This reverts commit e9ed1eb.

Eric has requested that this patch be taken through the libcrypto-next
tree, instead.

Signed-off-by: John Johansen <john.johansen@canonical.com>

Author: jrjohansen

security/apparmor/Kconfig

@@ -59,7 +59,8 @@ 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_LIB_SHA256
+	select CRYPTO
+	select CRYPTO_SHA256
 	default y
 	help
 	  This option selects whether introspection of loaded policy

security/apparmor/crypto.c

@@ -11,52 +11,113 @@
  * it should be.
  */
 
-#include <crypto/sha2.h>
+#include <crypto/hash.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 SHA256_DIGEST_SIZE;
+	return apparmor_hash_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(SHA256_DIGEST_SIZE, GFP_KERNEL);
+	hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
 	if (!hash)
 		return ERR_PTR(-ENOMEM);
 
-	sha256(data, len, hash);
+	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;
+
 	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)
 {
-	struct sha256_state state;
+	SHASH_DESC_ON_STACK(desc, apparmor_tfm);
+	int error;
 	__le32 le32_version = cpu_to_le32(version);
 
 	if (!aa_g_hash_policy)
 		return 0;
 
-	profile->hash = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
+	if (!apparmor_tfm)
+		return 0;
+
+	profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
 	if (!profile->hash)
 		return -ENOMEM;
 
-	sha256_init(&state);
-	sha256_update(&state, (u8 *)&le32_version, 4);
-	sha256_update(&state, (u8 *)start, len);
-	sha256_final(&state, profile->hash);
+	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;
+
 	return 0;
+
+fail:
+	kfree(profile->hash);
+	profile->hash = NULL;
+
+	return error;
 }
 
 static int __init init_profile_hash(void)
 {
-	if (apparmor_initialized)
-		aa_info_message("AppArmor sha256 policy hashing enabled");
+	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");
+
 	return 0;
 }
+
 late_initcall(init_profile_hash);