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Message-ID: <20250731184747.12335-1-ebiggers@kernel.org>
Date: Thu, 31 Jul 2025 11:47:47 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: keyrings@...r.kernel.org,
David Howells <dhowells@...hat.com>,
Jarkko Sakkinen <jarkko@...nel.org>,
Mimi Zohar <zohar@...ux.ibm.com>
Cc: linux-integrity@...r.kernel.org,
linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org,
Eric Biggers <ebiggers@...nel.org>
Subject: [PATCH] KEYS: encrypted: Use SHA-256 library instead of crypto_shash
Instead of the "sha256" crypto_shash, just use sha256(). Similarly,
instead of the "hmac(sha256)" crypto_shash, just use
hmac_sha256_usingrawkey(). This is simpler and faster.
Signed-off-by: Eric Biggers <ebiggers@...nel.org>
---
security/keys/Kconfig | 3 +-
security/keys/encrypted-keys/encrypted.c | 63 ++++--------------------
2 files changed, 11 insertions(+), 55 deletions(-)
diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index d4f5fc1e72638..64477e2c4a212 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -85,14 +85,13 @@ endif
config ENCRYPTED_KEYS
tristate "ENCRYPTED KEYS"
depends on KEYS
select CRYPTO
- select CRYPTO_HMAC
select CRYPTO_AES
select CRYPTO_CBC
- select CRYPTO_SHA256
+ select CRYPTO_LIB_SHA256
select CRYPTO_RNG
help
This option provides support for create/encrypting/decrypting keys
in the kernel. Encrypted keys are instantiated using kernel
generated random numbers or provided decrypted data, and are
diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c
index 831cb84fd75a1..513c09e2b01cf 100644
--- a/security/keys/encrypted-keys/encrypted.c
+++ b/security/keys/encrypted-keys/encrypted.c
@@ -25,22 +25,19 @@
#include <linux/random.h>
#include <linux/rcupdate.h>
#include <linux/scatterlist.h>
#include <linux/ctype.h>
#include <crypto/aes.h>
-#include <crypto/hash.h>
#include <crypto/sha2.h>
#include <crypto/skcipher.h>
#include <crypto/utils.h>
#include "encrypted.h"
#include "ecryptfs_format.h"
static const char KEY_TRUSTED_PREFIX[] = "trusted:";
static const char KEY_USER_PREFIX[] = "user:";
-static const char hash_alg[] = "sha256";
-static const char hmac_alg[] = "hmac(sha256)";
static const char blkcipher_alg[] = "cbc(aes)";
static const char key_format_default[] = "default";
static const char key_format_ecryptfs[] = "ecryptfs";
static const char key_format_enc32[] = "enc32";
static unsigned int ivsize;
@@ -52,12 +49,10 @@ static int blksize;
#define HASH_SIZE SHA256_DIGEST_SIZE
#define MAX_DATA_SIZE 4096
#define MIN_DATA_SIZE 20
#define KEY_ENC32_PAYLOAD_LEN 32
-static struct crypto_shash *hash_tfm;
-
enum {
Opt_new, Opt_load, Opt_update, Opt_err
};
enum {
@@ -327,39 +322,18 @@ static struct key *request_user_key(const char *master_desc, const u8 **master_k
*master_keylen = upayload->datalen;
error:
return ukey;
}
-static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
- const u8 *buf, unsigned int buflen)
-{
- struct crypto_shash *tfm;
- int err;
-
- tfm = crypto_alloc_shash(hmac_alg, 0, 0);
- if (IS_ERR(tfm)) {
- pr_err("encrypted_key: can't alloc %s transform: %ld\n",
- hmac_alg, PTR_ERR(tfm));
- return PTR_ERR(tfm);
- }
-
- err = crypto_shash_setkey(tfm, key, keylen);
- if (!err)
- err = crypto_shash_tfm_digest(tfm, buf, buflen, digest);
- crypto_free_shash(tfm);
- return err;
-}
-
enum derived_key_type { ENC_KEY, AUTH_KEY };
/* Derive authentication/encryption key from trusted key */
static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
const u8 *master_key, size_t master_keylen)
{
u8 *derived_buf;
unsigned int derived_buf_len;
- int ret;
derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
if (derived_buf_len < HASH_SIZE)
derived_buf_len = HASH_SIZE;
@@ -372,14 +346,13 @@ static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
else
strcpy(derived_buf, "ENC_KEY");
memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
master_keylen);
- ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len,
- derived_key);
+ sha256(derived_buf, derived_buf_len, derived_key);
kfree_sensitive(derived_buf);
- return ret;
+ return 0;
}
static struct skcipher_request *init_skcipher_req(const u8 *key,
unsigned int key_len)
{
@@ -501,14 +474,14 @@ static int datablob_hmac_append(struct encrypted_key_payload *epayload,
ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
if (ret < 0)
goto out;
digest = epayload->format + epayload->datablob_len;
- ret = calc_hmac(digest, derived_key, sizeof derived_key,
- epayload->format, epayload->datablob_len);
- if (!ret)
- dump_hmac(NULL, digest, HASH_SIZE);
+ hmac_sha256_usingrawkey(derived_key, sizeof(derived_key),
+ epayload->format, epayload->datablob_len,
+ digest);
+ dump_hmac(NULL, digest, HASH_SIZE);
out:
memzero_explicit(derived_key, sizeof(derived_key));
return ret;
}
@@ -532,13 +505,12 @@ static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
p = epayload->master_desc;
len -= strlen(epayload->format) + 1;
} else
p = epayload->format;
- ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
- if (ret < 0)
- goto out;
+ hmac_sha256_usingrawkey(derived_key, sizeof(derived_key), p, len,
+ digest);
ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
sizeof(digest));
if (ret) {
ret = -EINVAL;
dump_hmac("datablob",
@@ -1009,33 +981,18 @@ EXPORT_SYMBOL_GPL(key_type_encrypted);
static int __init init_encrypted(void)
{
int ret;
- hash_tfm = crypto_alloc_shash(hash_alg, 0, 0);
- if (IS_ERR(hash_tfm)) {
- pr_err("encrypted_key: can't allocate %s transform: %ld\n",
- hash_alg, PTR_ERR(hash_tfm));
- return PTR_ERR(hash_tfm);
- }
-
ret = aes_get_sizes();
if (ret < 0)
- goto out;
- ret = register_key_type(&key_type_encrypted);
- if (ret < 0)
- goto out;
- return 0;
-out:
- crypto_free_shash(hash_tfm);
- return ret;
-
+ return ret;
+ return register_key_type(&key_type_encrypted);
}
static void __exit cleanup_encrypted(void)
{
- crypto_free_shash(hash_tfm);
unregister_key_type(&key_type_encrypted);
}
late_initcall(init_encrypted);
module_exit(cleanup_encrypted);
base-commit: d6084bb815c453de27af8071a23163a711586a6c
--
2.50.1
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