@@ -45,9 +45,7 @@ config BIG_KEYS
bool "Large payload keys"
depends on KEYS
depends on TMPFS
- select CRYPTO
- select CRYPTO_AES
- select CRYPTO_GCM
+ select ZINC_CHACHA20POLY1305
help
This option provides support for holding large keys within the kernel
(for example Kerberos ticket caches). The data may be stored out to
@@ -1,6 +1,6 @@
/* Large capacity key type
*
- * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * Copyright (C) 2017-2018 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)
*
@@ -16,20 +16,10 @@
#include <linux/file.h>
#include <linux/shmem_fs.h>
#include <linux/err.h>
-#include <linux/scatterlist.h>
#include <linux/random.h>
-#include <linux/vmalloc.h>
#include <keys/user-type.h>
#include <keys/big_key-type.h>
-#include <crypto/aead.h>
-#include <crypto/gcm.h>
-
-struct big_key_buf {
- unsigned int nr_pages;
- void *virt;
- struct scatterlist *sg;
- struct page *pages[];
-};
+#include <zinc/chacha20poly1305.h>
/*
* Layout of key payload words.
@@ -42,14 +32,6 @@ enum {
};
/*
- * Crypto operation with big_key data
- */
-enum big_key_op {
- BIG_KEY_ENC,
- BIG_KEY_DEC,
-};
-
-/*
* If the data is under this limit, there's no point creating a shm file to
* hold it as the permanently resident metadata for the shmem fs will be at
* least as large as the data.
@@ -57,16 +39,6 @@ enum big_key_op {
#define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry))
/*
- * Key size for big_key data encryption
- */
-#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
* arbitrary blob of data as the payload
*/
@@ -79,136 +51,20 @@ 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 */
+ /* no ->update(); don't add it without changing chacha20poly1305's nonce */
};
/*
- * Crypto names for big_key data authenticated encryption
- */
-static const char big_key_alg_name[] = "gcm(aes)";
-#define BIG_KEY_IV_SIZE GCM_AES_IV_SIZE
-
-/*
- * Crypto algorithms for big_key data authenticated encryption
- */
-static struct crypto_aead *big_key_aead;
-
-/*
- * Since changing the key affects the entire object, we need a mutex.
- */
-static DEFINE_MUTEX(big_key_aead_lock);
-
-/*
- * Encrypt/decrypt big_key data
- */
-static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t datalen, u8 *key)
-{
- int ret;
- 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[BIG_KEY_IV_SIZE];
-
- aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL);
- if (!aead_req)
- return -ENOMEM;
-
- memset(zero_nonce, 0, sizeof(zero_nonce));
- aead_request_set_crypt(aead_req, buf->sg, buf->sg, 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;
- }
- if (op == BIG_KEY_ENC)
- ret = crypto_aead_encrypt(aead_req);
- else
- ret = crypto_aead_decrypt(aead_req);
-error:
- mutex_unlock(&big_key_aead_lock);
- aead_request_free(aead_req);
- return ret;
-}
-
-/*
- * Free up the buffer.
- */
-static void big_key_free_buffer(struct big_key_buf *buf)
-{
- unsigned int i;
-
- if (buf->virt) {
- memset(buf->virt, 0, buf->nr_pages * PAGE_SIZE);
- vunmap(buf->virt);
- }
-
- for (i = 0; i < buf->nr_pages; i++)
- if (buf->pages[i])
- __free_page(buf->pages[i]);
-
- kfree(buf);
-}
-
-/*
- * Allocate a buffer consisting of a set of pages with a virtual mapping
- * applied over them.
- */
-static void *big_key_alloc_buffer(size_t len)
-{
- struct big_key_buf *buf;
- unsigned int npg = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
- unsigned int i, l;
-
- buf = kzalloc(sizeof(struct big_key_buf) +
- sizeof(struct page) * npg +
- sizeof(struct scatterlist) * npg,
- GFP_KERNEL);
- if (!buf)
- return NULL;
-
- buf->nr_pages = npg;
- buf->sg = (void *)(buf->pages + npg);
- sg_init_table(buf->sg, npg);
-
- for (i = 0; i < buf->nr_pages; i++) {
- buf->pages[i] = alloc_page(GFP_KERNEL);
- if (!buf->pages[i])
- goto nomem;
-
- l = min_t(size_t, len, PAGE_SIZE);
- sg_set_page(&buf->sg[i], buf->pages[i], l, 0);
- len -= l;
- }
-
- buf->virt = vmap(buf->pages, buf->nr_pages, VM_MAP, PAGE_KERNEL);
- if (!buf->virt)
- goto nomem;
-
- return buf;
-
-nomem:
- big_key_free_buffer(buf);
- return NULL;
-}
-
-/*
* Preparse a big key
*/
int big_key_preparse(struct key_preparsed_payload *prep)
{
- struct big_key_buf *buf;
struct path *path = (struct path *)&prep->payload.data[big_key_path];
struct file *file;
- u8 *enckey;
+ u8 *buf, *enckey;
ssize_t written;
- size_t datalen = prep->datalen, enclen = datalen + ENC_AUTHTAG_SIZE;
+ size_t datalen = prep->datalen;
+ size_t enclen = datalen + CHACHA20POLY1305_AUTHTAG_SIZE;
int ret;
if (datalen <= 0 || datalen > 1024 * 1024 || !prep->data)
@@ -224,28 +80,28 @@ int big_key_preparse(struct key_preparsed_payload *prep)
* to be swapped out if needed.
*
* File content is stored encrypted with randomly generated key.
+ * Since the key is random for each file, we can set the nonce
+ * to zero, provided we never define a ->update() call.
*/
loff_t pos = 0;
- buf = big_key_alloc_buffer(enclen);
+ buf = kvmalloc(enclen, GFP_KERNEL);
if (!buf)
return -ENOMEM;
- memcpy(buf->virt, prep->data, datalen);
/* generate random key */
- enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL);
+ enckey = kmalloc(CHACHA20POLY1305_KEY_SIZE, GFP_KERNEL);
if (!enckey) {
ret = -ENOMEM;
goto error;
}
- ret = get_random_bytes_wait(enckey, ENC_KEY_SIZE);
+ ret = get_random_bytes_wait(enckey, CHACHA20POLY1305_KEY_SIZE);
if (unlikely(ret))
goto err_enckey;
- /* encrypt aligned data */
- ret = big_key_crypt(BIG_KEY_ENC, buf, datalen, enckey);
- if (ret)
- goto err_enckey;
+ /* encrypt data */
+ chacha20poly1305_encrypt(buf, prep->data, datalen, NULL, 0,
+ 0, enckey);
/* save aligned data to file */
file = shmem_kernel_file_setup("", enclen, 0);
@@ -254,7 +110,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
goto err_enckey;
}
- written = kernel_write(file, buf->virt, enclen, &pos);
+ written = kernel_write(file, buf, enclen, &pos);
if (written != enclen) {
ret = written;
if (written >= 0)
@@ -269,7 +125,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
*path = file->f_path;
path_get(path);
fput(file);
- big_key_free_buffer(buf);
+ kvfree(buf);
} else {
/* Just store the data in a buffer */
void *data = kmalloc(datalen, GFP_KERNEL);
@@ -287,7 +143,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
err_enckey:
kzfree(enckey);
error:
- big_key_free_buffer(buf);
+ kvfree(buf);
return ret;
}
@@ -365,14 +221,13 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
return datalen;
if (datalen > BIG_KEY_FILE_THRESHOLD) {
- struct big_key_buf *buf;
struct path *path = (struct path *)&key->payload.data[big_key_path];
struct file *file;
- u8 *enckey = (u8 *)key->payload.data[big_key_data];
- size_t enclen = datalen + ENC_AUTHTAG_SIZE;
+ u8 *buf, *enckey = (u8 *)key->payload.data[big_key_data];
+ size_t enclen = datalen + CHACHA20POLY1305_AUTHTAG_SIZE;
loff_t pos = 0;
- buf = big_key_alloc_buffer(enclen);
+ buf = kvmalloc(enclen, GFP_KERNEL);
if (!buf)
return -ENOMEM;
@@ -383,26 +238,27 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
}
/* read file to kernel and decrypt */
- ret = kernel_read(file, buf->virt, enclen, &pos);
+ ret = kernel_read(file, buf, enclen, &pos);
if (ret >= 0 && ret != enclen) {
ret = -EIO;
goto err_fput;
}
- ret = big_key_crypt(BIG_KEY_DEC, buf, enclen, enckey);
- if (ret)
+ ret = chacha20poly1305_decrypt(buf, buf, enclen, NULL, 0, 0,
+ enckey) ? 0 : -EINVAL;
+ if (unlikely(ret))
goto err_fput;
ret = datalen;
/* copy decrypted data to user */
- if (copy_to_user(buffer, buf->virt, datalen) != 0)
+ if (copy_to_user(buffer, buf, datalen) != 0)
ret = -EFAULT;
err_fput:
fput(file);
error:
- big_key_free_buffer(buf);
+ kvfree(buf);
} else {
ret = datalen;
if (copy_to_user(buffer, key->payload.data[big_key_data],
@@ -418,39 +274,7 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
*/
static int __init big_key_init(void)
{
- int ret;
-
- /* init block 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);
- return ret;
- }
-
- if (unlikely(crypto_aead_ivsize(big_key_aead) != BIG_KEY_IV_SIZE)) {
- WARN(1, "big key algorithm changed?");
- ret = -EINVAL;
- goto free_aead;
- }
-
- 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;
- }
-
- ret = register_key_type(&key_type_big_key);
- if (ret < 0) {
- pr_err("Can't register type: %d\n", ret);
- goto free_aead;
- }
-
- return 0;
-
-free_aead:
- crypto_free_aead(big_key_aead);
- return ret;
+ return register_key_type(&key_type_big_key);
}
late_initcall(big_key_init);