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-rw-r--r--security/keys/Kconfig4
-rw-r--r--security/keys/big_key.c139
2 files changed, 66 insertions, 77 deletions
diff --git a/security/keys/Kconfig b/security/keys/Kconfig
index a7a23b5541f8..91eafada3164 100644
--- a/security/keys/Kconfig
+++ b/security/keys/Kconfig
@@ -45,10 +45,8 @@ config BIG_KEYS
bool "Large payload keys"
depends on KEYS
depends on TMPFS
- depends on (CRYPTO_ANSI_CPRNG = y || CRYPTO_DRBG = y)
select CRYPTO_AES
- select CRYPTO_ECB
- select CRYPTO_RNG
+ select CRYPTO_GCM
help
This option provides support for holding large keys within the kernel
(for example Kerberos ticket caches). The data may be stored out to
diff --git a/security/keys/big_key.c b/security/keys/big_key.c
index 6acb00f6f22c..e607830b6154 100644
--- a/security/keys/big_key.c
+++ b/security/keys/big_key.c
@@ -1,5 +1,6 @@
/* Large capacity key type
*
+ * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
@@ -16,10 +17,10 @@
#include <linux/shmem_fs.h>
#include <linux/err.h>
#include <linux/scatterlist.h>
+#include <linux/random.h>
#include <keys/user-type.h>
#include <keys/big_key-type.h>
-#include <crypto/rng.h>
-#include <crypto/skcipher.h>
+#include <crypto/aead.h>
/*
* Layout of key payload words.
@@ -49,7 +50,12 @@ enum big_key_op {
/*
* Key size for big_key data encryption
*/
-#define ENC_KEY_SIZE 16
+#define ENC_KEY_SIZE 32
+
+/*
+ * Authentication tag length
+ */
+#define ENC_AUTHTAG_SIZE 16
/*
* big_key defined keys take an arbitrary string as the description and an
@@ -64,57 +70,62 @@ struct key_type key_type_big_key = {
.destroy = big_key_destroy,
.describe = big_key_describe,
.read = big_key_read,
+ /* no ->update(); don't add it without changing big_key_crypt() nonce */
};
/*
- * Crypto names for big_key data encryption
+ * Crypto names for big_key data authenticated encryption
*/
-static const char big_key_rng_name[] = "stdrng";
-static const char big_key_alg_name[] = "ecb(aes)";
+static const char big_key_alg_name[] = "gcm(aes)";
/*
- * Crypto algorithms for big_key data encryption
+ * Crypto algorithms for big_key data authenticated encryption
*/
-static struct crypto_rng *big_key_rng;
-static struct crypto_skcipher *big_key_skcipher;
+static struct crypto_aead *big_key_aead;
/*
- * Generate random key to encrypt big_key data
+ * Since changing the key affects the entire object, we need a mutex.
*/
-static inline int big_key_gen_enckey(u8 *key)
-{
- return crypto_rng_get_bytes(big_key_rng, key, ENC_KEY_SIZE);
-}
+static DEFINE_MUTEX(big_key_aead_lock);
/*
* Encrypt/decrypt big_key data
*/
static int big_key_crypt(enum big_key_op op, u8 *data, size_t datalen, u8 *key)
{
- int ret = -EINVAL;
+ int ret;
struct scatterlist sgio;
- SKCIPHER_REQUEST_ON_STACK(req, big_key_skcipher);
-
- if (crypto_skcipher_setkey(big_key_skcipher, key, ENC_KEY_SIZE)) {
+ struct aead_request *aead_req;
+ /* We always use a zero nonce. The reason we can get away with this is
+ * because we're using a different randomly generated key for every
+ * different encryption. Notably, too, key_type_big_key doesn't define
+ * an .update function, so there's no chance we'll wind up reusing the
+ * key to encrypt updated data. Simply put: one key, one encryption.
+ */
+ u8 zero_nonce[crypto_aead_ivsize(big_key_aead)];
+
+ aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL);
+ if (!aead_req)
+ return -ENOMEM;
+
+ memset(zero_nonce, 0, sizeof(zero_nonce));
+ sg_init_one(&sgio, data, datalen + (op == BIG_KEY_ENC ? ENC_AUTHTAG_SIZE : 0));
+ aead_request_set_crypt(aead_req, &sgio, &sgio, datalen, zero_nonce);
+ aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
+ aead_request_set_ad(aead_req, 0);
+
+ mutex_lock(&big_key_aead_lock);
+ if (crypto_aead_setkey(big_key_aead, key, ENC_KEY_SIZE)) {
ret = -EAGAIN;
goto error;
}
-
- skcipher_request_set_tfm(req, big_key_skcipher);
- skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
- NULL, NULL);
-
- sg_init_one(&sgio, data, datalen);
- skcipher_request_set_crypt(req, &sgio, &sgio, datalen, NULL);
-
if (op == BIG_KEY_ENC)
- ret = crypto_skcipher_encrypt(req);
+ ret = crypto_aead_encrypt(aead_req);
else
- ret = crypto_skcipher_decrypt(req);
-
- skcipher_request_zero(req);
-
+ ret = crypto_aead_decrypt(aead_req);
error:
+ mutex_unlock(&big_key_aead_lock);
+ aead_request_free(aead_req);
return ret;
}
@@ -146,16 +157,13 @@ int big_key_preparse(struct key_preparsed_payload *prep)
*
* File content is stored encrypted with randomly generated key.
*/
- size_t enclen = ALIGN(datalen, crypto_skcipher_blocksize(big_key_skcipher));
+ size_t enclen = datalen + ENC_AUTHTAG_SIZE;
loff_t pos = 0;
- /* prepare aligned data to encrypt */
data = kmalloc(enclen, GFP_KERNEL);
if (!data)
return -ENOMEM;
-
memcpy(data, prep->data, datalen);
- memset(data + datalen, 0x00, enclen - datalen);
/* generate random key */
enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL);
@@ -163,13 +171,12 @@ int big_key_preparse(struct key_preparsed_payload *prep)
ret = -ENOMEM;
goto error;
}
-
- ret = big_key_gen_enckey(enckey);
- if (ret)
+ ret = get_random_bytes_wait(enckey, ENC_KEY_SIZE);
+ if (unlikely(ret))
goto err_enckey;
/* encrypt aligned data */
- ret = big_key_crypt(BIG_KEY_ENC, data, enclen, enckey);
+ ret = big_key_crypt(BIG_KEY_ENC, data, datalen, enckey);
if (ret)
goto err_enckey;
@@ -195,7 +202,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
*path = file->f_path;
path_get(path);
fput(file);
- kfree(data);
+ kzfree(data);
} else {
/* Just store the data in a buffer */
void *data = kmalloc(datalen, GFP_KERNEL);
@@ -211,9 +218,9 @@ int big_key_preparse(struct key_preparsed_payload *prep)
err_fput:
fput(file);
err_enckey:
- kfree(enckey);
+ kzfree(enckey);
error:
- kfree(data);
+ kzfree(data);
return ret;
}
@@ -227,7 +234,7 @@ void big_key_free_preparse(struct key_preparsed_payload *prep)
path_put(path);
}
- kfree(prep->payload.data[big_key_data]);
+ kzfree(prep->payload.data[big_key_data]);
}
/*
@@ -259,7 +266,7 @@ void big_key_destroy(struct key *key)
path->mnt = NULL;
path->dentry = NULL;
}
- kfree(key->payload.data[big_key_data]);
+ kzfree(key->payload.data[big_key_data]);
key->payload.data[big_key_data] = NULL;
}
@@ -295,7 +302,7 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
struct file *file;
u8 *data;
u8 *enckey = (u8 *)key->payload.data[big_key_data];
- size_t enclen = ALIGN(datalen, crypto_skcipher_blocksize(big_key_skcipher));
+ size_t enclen = datalen + ENC_AUTHTAG_SIZE;
loff_t pos = 0;
data = kmalloc(enclen, GFP_KERNEL);
@@ -328,7 +335,7 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
err_fput:
fput(file);
error:
- kfree(data);
+ kzfree(data);
} else {
ret = datalen;
if (copy_to_user(buffer, key->payload.data[big_key_data],
@@ -344,47 +351,31 @@ error:
*/
static int __init big_key_init(void)
{
- struct crypto_skcipher *cipher;
- struct crypto_rng *rng;
int ret;
- rng = crypto_alloc_rng(big_key_rng_name, 0, 0);
- if (IS_ERR(rng)) {
- pr_err("Can't alloc rng: %ld\n", PTR_ERR(rng));
- return PTR_ERR(rng);
- }
-
- big_key_rng = rng;
-
- /* seed RNG */
- ret = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
- if (ret) {
- pr_err("Can't reset rng: %d\n", ret);
- goto error_rng;
- }
-
/* init block cipher */
- cipher = crypto_alloc_skcipher(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
- if (IS_ERR(cipher)) {
- ret = PTR_ERR(cipher);
+ big_key_aead = crypto_alloc_aead(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(big_key_aead)) {
+ ret = PTR_ERR(big_key_aead);
pr_err("Can't alloc crypto: %d\n", ret);
- goto error_rng;
+ return ret;
+ }
+ ret = crypto_aead_setauthsize(big_key_aead, ENC_AUTHTAG_SIZE);
+ if (ret < 0) {
+ pr_err("Can't set crypto auth tag len: %d\n", ret);
+ goto free_aead;
}
-
- big_key_skcipher = cipher;
ret = register_key_type(&key_type_big_key);
if (ret < 0) {
pr_err("Can't register type: %d\n", ret);
- goto error_cipher;
+ goto free_aead;
}
return 0;
-error_cipher:
- crypto_free_skcipher(big_key_skcipher);
-error_rng:
- crypto_free_rng(big_key_rng);
+free_aead:
+ crypto_free_aead(big_key_aead);
return ret;
}