- 根目录:
- security
- keys
- encrypted-keys
- encrypted.c
/*
* Copyright (C) 2010 IBM Corporation
* Copyright (C) 2010 Politecnico di Torino, Italy
* TORSEC group -- http://security.polito.it
*
* Authors:
* Mimi Zohar <zohar@us.ibm.com>
* Roberto Sassu <roberto.sassu@polito.it>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2 of the License.
*
* See Documentation/security/keys-trusted-encrypted.txt
*/
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/parser.h>
#include <linux/string.h>
#include <linux/err.h>
#include <keys/user-type.h>
#include <keys/trusted-type.h>
#include <keys/encrypted-type.h>
#include <linux/key-type.h>
#include <linux/random.h>
#include <linux/rcupdate.h>
#include <linux/scatterlist.h>
#include <linux/crypto.h>
#include <linux/ctype.h>
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <crypto/aes.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 unsigned int ivsize;
static int blksize;
#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
#define KEY_ECRYPTFS_DESC_LEN 16
#define HASH_SIZE SHA256_DIGEST_SIZE
#define MAX_DATA_SIZE 4096
#define MIN_DATA_SIZE 20
struct sdesc {
struct shash_desc shash;
char ctx[];
};
static struct crypto_shash *hashalg;
static struct crypto_shash *hmacalg;
enum {
Opt_err = -1, Opt_new, Opt_load, Opt_update
};
enum {
Opt_error = -1, Opt_default, Opt_ecryptfs
};
static const match_table_t key_format_tokens = {
{Opt_default, "default"},
{Opt_ecryptfs, "ecryptfs"},
{Opt_error, NULL}
};
static const match_table_t key_tokens = {
{Opt_new, "new"},
{Opt_load, "load"},
{Opt_update, "update"},
{Opt_err, NULL}
};
static int aes_get_sizes(void)
{
struct crypto_blkcipher *tfm;
tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm)) {
pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
PTR_ERR(tfm));
return PTR_ERR(tfm);
}
ivsize = crypto_blkcipher_ivsize(tfm);
blksize = crypto_blkcipher_blocksize(tfm);
crypto_free_blkcipher(tfm);
return 0;
}
/*
* valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
*
* The description of a encrypted key with format 'ecryptfs' must contain
* exactly 16 hexadecimal characters.
*
*/
static int valid_ecryptfs_desc(const char *ecryptfs_desc)
{
int i;
if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
pr_err("encrypted_key: key description must be %d hexadecimal "
"characters long\n", KEY_ECRYPTFS_DESC_LEN);
return -EINVAL;
}
for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
if (!isxdigit(ecryptfs_desc[i])) {
pr_err("encrypted_key: key description must contain "
"only hexadecimal characters\n");
return -EINVAL;
}
}
return 0;
}
/*
* valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
*
* key-type:= "trusted:" | "user:"
* desc:= master-key description
*
* Verify that 'key-type' is valid and that 'desc' exists. On key update,
* only the master key description is permitted to change, not the key-type.
* The key-type remains constant.
*
* On success returns 0, otherwise -EINVAL.
*/
static int valid_master_desc(const char *new_desc, const char *orig_desc)
{
if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
goto out;
if (orig_desc)
if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
goto out;
} else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
goto out;
if (orig_desc)
if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
goto out;
} else
goto out;
return 0;
out:
return -EINVAL;
}
/*
* datablob_parse - parse the keyctl data
*
* datablob format:
* new [<format>] <master-key name> <decrypted data length>
* load [<format>] <master-key name> <decrypted data length>
* <encrypted iv + data>
* update <new-master-key name>
*
* Tokenizes a copy of the keyctl data, returning a pointer to each token,
* which is null terminated.
*
* On success returns 0, otherwise -EINVAL.
*/
static int datablob_parse(char *datablob, const char **format,
char **master_desc, char **decrypted_datalen,
char **hex_encoded_iv)
{
substring_t args[MAX_OPT_ARGS];
int ret = -EINVAL;
int key_cmd;
int key_format;
char *p, *keyword;
keyword = strsep(&datablob, " \t");
if (!keyword) {
pr_info("encrypted_key: insufficient parameters specified\n");
return ret;
}
key_cmd = match_token(keyword, key_tokens, args);
/* Get optional format: default | ecryptfs */
p = strsep(&datablob, " \t");
if (!p) {
pr_err("encrypted_key: insufficient parameters specified\n");
return ret;
}
key_format = match_token(p, key_format_tokens, args);
switch (key_format) {
case Opt_ecryptfs:
case Opt_default:
*format = p;
*master_desc = strsep(&datablob, " \t");
break;
case Opt_error:
*master_desc = p;
break;
}
if (!*master_desc) {
pr_info("encrypted_key: master key parameter is missing\n");
goto out;
}
if (valid_master_desc(*master_desc, NULL) < 0) {
pr_info("encrypted_key: master key parameter \'%s\' "
"is invalid\n", *master_desc);
goto out;
}
if (decrypted_datalen) {
*decrypted_datalen = strsep(&datablob, " \t");
if (!*decrypted_datalen) {
pr_info("encrypted_key: keylen parameter is missing\n");
goto out;
}
}
switch (key_cmd) {
case Opt_new:
if (!decrypted_datalen) {
pr_info("encrypted_key: keyword \'%s\' not allowed "
"when called from .update method\n", keyword);
break;
}
ret = 0;
break;
case Opt_load:
if (!decrypted_datalen) {
pr_info("encrypted_key: keyword \'%s\' not allowed "
"when called from .update method\n", keyword);
break;
}
*hex_encoded_iv = strsep(&datablob, " \t");
if (!*hex_encoded_iv) {
pr_info("encrypted_key: hex blob is missing\n");
break;
}
ret = 0;
break;
case Opt_update:
if (decrypted_datalen) {
pr_info("encrypted_key: keyword \'%s\' not allowed "
"when called from .instantiate method\n",
keyword);
break;
}
ret = 0;
break;
case Opt_err:
pr_info("encrypted_key: keyword \'%s\' not recognized\n",
keyword);
break;
}
out:
return ret;
}
/*
* datablob_format - format as an ascii string, before copying to userspace
*/
static char *datablob_format(struct encrypted_key_payload *epayload,
size_t asciiblob_len)
{
char *ascii_buf, *bufp;
u8 *iv = epayload->iv;
int len;
int i;
ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
if (!ascii_buf)
goto out;
ascii_buf[asciiblob_len] = '\0';
/* copy datablob master_desc and datalen strings */
len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
epayload->master_desc, epayload->datalen);
/* convert the hex encoded iv, encrypted-data and HMAC to ascii */
bufp = &ascii_buf[len];
for (i = 0; i < (asciiblob_len - len) / 2; i++)
bufp = hex_byte_pack(bufp, iv[i]);
out:
return ascii_buf;
}
/*
* request_user_key - request the user key
*
* Use a user provided key to encrypt/decrypt an encrypted-key.
*/
static struct key *request_user_key(const char *master_desc, u8 **master_key,
size_t *master_keylen)
{
struct user_key_payload *upayload;
struct key *ukey;
ukey = request_key(&key_type_user, master_desc, NULL);
if (IS_ERR(ukey))
goto error;
down_read(&ukey->sem);
upayload = ukey->payload.data;
*master_key = upayload->data;
*master_keylen = upayload->datalen;
error:
return ukey;
}
static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
{
struct sdesc *sdesc;
int size;
size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
sdesc = kmalloc(size, GFP_KERNEL);
if (!sdesc)
return ERR_PTR(-ENOMEM);
sdesc->shash.tfm = alg;
sdesc->shash.flags = 0x0;
return sdesc;
}
static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
const u8 *buf, unsigned int buflen)
{
struct sdesc *sdesc;
int ret;
sdesc = alloc_sdesc(hmacalg);
if (IS_ERR(sdesc)) {
pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
return PTR_ERR(sdesc);
}
ret = crypto_shash_setkey(hmacalg, key, keylen);
if (!ret)
ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
kfree(sdesc);
return ret;
}
static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
{
struct sdesc *sdesc;
int ret;
sdesc = alloc_sdesc(hashalg);
if (IS_ERR(sdesc)) {
pr_info("encrypted_key: can't alloc %s\n", hash_alg);
return PTR_ERR(sdesc);
}
ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
kfree(sdesc);
return ret;
}
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;
derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
if (!derived_buf) {
pr_err("encrypted_key: out of memory\n");
return -ENOMEM;
}
if (key_type)
strcpy(derived_buf, "AUTH_KEY");
else
strcpy(derived_buf, "ENC_KEY");
memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
master_keylen);
ret = calc_hash(derived_key, derived_buf, derived_buf_len);
kfree(derived_buf);
return ret;
}
static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key,
unsigned int key_len, const u8 *iv,
unsigned int ivsize)
{
int ret;
desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(desc->tfm)) {
pr_err("encrypted_key: failed to load %s transform (%ld)\n",
blkcipher_alg, PTR_ERR(desc->tfm));
return PTR_ERR(desc->tfm);
}
desc->flags = 0;
ret = crypto_blkcipher_setkey(desc->tfm, key, key_len);
if (ret < 0) {
pr_err("encrypted_key: failed to setkey (%d)\n", ret);
crypto_free_blkcipher(desc->tfm);
return ret;
}
crypto_blkcipher_set_iv(desc->tfm, iv, ivsize);
return 0;
}
static struct key *request_master_key(struct encrypted_key_payload *epayload,
u8 **master_key, size_t *master_keylen)
{
struct key *mkey = NULL;
if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
KEY_TRUSTED_PREFIX_LEN)) {
mkey = request_trusted_key(epayload->master_desc +
KEY_TRUSTED_PREFIX_LEN,
master_key, master_keylen);
} else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
KEY_USER_PREFIX_LEN)) {
mkey = request_user_key(epayload->master_desc +
KEY_USER_PREFIX_LEN,
master_key, master_keylen);
} else
goto out;
if (IS_ERR(mkey)) {
int ret = PTR_ERR(mkey);
if (ret == -ENOTSUPP)
pr_info("encrypted_key: key %s not supported",
epayload->master_desc);
else
pr_info("encrypted_key: key %s not found",
epayload->master_desc);
goto out;
}
dump_master_key(*master_key, *master_keylen);
out:
return mkey;
}
/* Before returning data to userspace, encrypt decrypted data. */
static int derived_key_encrypt(struct encrypted_key_payload *epayload,
const u8 *derived_key,
unsigned int derived_keylen)
{
struct scatterlist sg_in[2];
struct scatterlist sg_out[1];
struct blkcipher_desc desc;
unsigned int encrypted_datalen;
unsigned int padlen;
char pad[16];
int ret;
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
padlen = encrypted_datalen - epayload->decrypted_datalen;
ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
epayload->iv, ivsize);
if (ret < 0)
goto out;
dump_decrypted_data(epayload);
memset(pad, 0, sizeof pad);
sg_init_table(sg_in, 2);
sg_set_buf(&sg_in[0], epayload->decrypted_data,
epayload->decrypted_datalen);
sg_set_buf(&sg_in[1], pad, padlen);
sg_init_table(sg_out, 1);
sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen);
crypto_free_blkcipher(desc.tfm);
if (ret < 0)
pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
else
dump_encrypted_data(epayload, encrypted_datalen);
out:
return ret;
}
static int datablob_hmac_append(struct encrypted_key_payload *epayload,
const u8 *master_key, size_t master_keylen)
{
u8 derived_key[HASH_SIZE];
u8 *digest;
int ret;
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);
out:
return ret;
}
/* verify HMAC before decrypting encrypted key */
static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
const u8 *format, const u8 *master_key,
size_t master_keylen)
{
u8 derived_key[HASH_SIZE];
u8 digest[HASH_SIZE];
int ret;
char *p;
unsigned short len;
ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
if (ret < 0)
goto out;
len = epayload->datablob_len;
if (!format) {
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;
ret = memcmp(digest, epayload->format + epayload->datablob_len,
sizeof digest);
if (ret) {
ret = -EINVAL;
dump_hmac("datablob",
epayload->format + epayload->datablob_len,
HASH_SIZE);
dump_hmac("calc", digest, HASH_SIZE);
}
out:
return ret;
}
static int derived_key_decrypt(struct encrypted_key_payload *epayload,
const u8 *derived_key,
unsigned int derived_keylen)
{
struct scatterlist sg_in[1];
struct scatterlist sg_out[2];
struct blkcipher_desc desc;
unsigned int encrypted_datalen;
char pad[16];
int ret;
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
epayload->iv, ivsize);
if (ret < 0)
goto out;
dump_encrypted_data(epayload, encrypted_datalen);
memset(pad, 0, sizeof pad);
sg_init_table(sg_in, 1);
sg_init_table(sg_out, 2);
sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
sg_set_buf(&sg_out[0], epayload->decrypted_data,
epayload->decrypted_datalen);
sg_set_buf(&sg_out[1], pad, sizeof pad);
ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen);
crypto_free_blkcipher(desc.tfm);
if (ret < 0)
goto out;
dump_decrypted_data(epayload);
out:
return ret;
}
/* Allocate memory for decrypted key and datablob. */
static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
const char *format,
const char *master_desc,
const char *datalen)
{
struct encrypted_key_payload *epayload = NULL;
unsigned short datablob_len;
unsigned short decrypted_datalen;
unsigned short payload_datalen;
unsigned int encrypted_datalen;
unsigned int format_len;
long dlen;
int ret;
ret = kstrtol(datalen, 10, &dlen);
if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
return ERR_PTR(-EINVAL);
format_len = (!format) ? strlen(key_format_default) : strlen(format);
decrypted_datalen = dlen;
payload_datalen = decrypted_datalen;
if (format && !strcmp(format, key_format_ecryptfs)) {
if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
pr_err("encrypted_key: keylen for the ecryptfs format "
"must be equal to %d bytes\n",
ECRYPTFS_MAX_KEY_BYTES);
return ERR_PTR(-EINVAL);
}
decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
payload_datalen = sizeof(struct ecryptfs_auth_tok);
}
encrypted_datalen = roundup(decrypted_datalen, blksize);
datablob_len = format_len + 1 + strlen(master_desc) + 1
+ strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
ret = key_payload_reserve(key, payload_datalen + datablob_len
+ HASH_SIZE + 1);
if (ret < 0)
return ERR_PTR(ret);
epayload = kzalloc(sizeof(*epayload) + payload_datalen +
datablob_len + HASH_SIZE + 1, GFP_KERNEL);
if (!epayload)
return ERR_PTR(-ENOMEM);
epayload->payload_datalen = payload_datalen;
epayload->decrypted_datalen = decrypted_datalen;
epayload->datablob_len = datablob_len;
return epayload;
}
static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
const char *format, const char *hex_encoded_iv)
{
struct key *mkey;
u8 derived_key[HASH_SIZE];
u8 *master_key;
u8 *hmac;
const char *hex_encoded_data;
unsigned int encrypted_datalen;
size_t master_keylen;
size_t asciilen;
int ret;
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
if (strlen(hex_encoded_iv) != asciilen)
return -EINVAL;
hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
if (ret < 0)
return -EINVAL;
ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
encrypted_datalen);
if (ret < 0)
return -EINVAL;
hmac = epayload->format + epayload->datablob_len;
ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
HASH_SIZE);
if (ret < 0)
return -EINVAL;
mkey = request_master_key(epayload, &master_key, &master_keylen);
if (IS_ERR(mkey))
return PTR_ERR(mkey);
ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
if (ret < 0) {
pr_err("encrypted_key: bad hmac (%d)\n", ret);
goto out;
}
ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
if (ret < 0)
goto out;
ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
if (ret < 0)
pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
out:
up_read(&mkey->sem);
key_put(mkey);
return ret;
}
static void __ekey_init(struct encrypted_key_payload *epayload,
const char *format, const char *master_desc,
const char *datalen)
{
unsigned int format_len;
format_len = (!format) ? strlen(key_format_default) : strlen(format);
epayload->format = epayload->payload_data + epayload->payload_datalen;
epayload->master_desc = epayload->format + format_len + 1;
epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
epayload->iv = epayload->datalen + strlen(datalen) + 1;
epayload->encrypted_data = epayload->iv + ivsize + 1;
epayload->decrypted_data = epayload->payload_data;
if (!format)
memcpy(epayload->format, key_format_default, format_len);
else {
if (!strcmp(format, key_format_ecryptfs))
epayload->decrypted_data =
ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
memcpy(epayload->format, format, format_len);
}
memcpy(epayload->master_desc, master_desc, strlen(master_desc));
memcpy(epayload->datalen, datalen, strlen(datalen));
}
/*
* encrypted_init - initialize an encrypted key
*
* For a new key, use a random number for both the iv and data
* itself. For an old key, decrypt the hex encoded data.
*/
static int encrypted_init(struct encrypted_key_payload *epayload,
const char *key_desc, const char *format,
const char *master_desc, const char *datalen,
const char *hex_encoded_iv)
{
int ret = 0;
if (format && !strcmp(format, key_format_ecryptfs)) {
ret = valid_ecryptfs_desc(key_desc);
if (ret < 0)
return ret;
ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
key_desc);
}
__ekey_init(epayload, format, master_desc, datalen);
if (!hex_encoded_iv) {
get_random_bytes(epayload->iv, ivsize);
get_random_bytes(epayload->decrypted_data,
epayload->decrypted_datalen);
} else
ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
return ret;
}
/*
* encrypted_instantiate - instantiate an encrypted key
*
* Decrypt an existing encrypted datablob or create a new encrypted key
* based on a kernel random number.
*
* On success, return 0. Otherwise return errno.
*/
static int encrypted_instantiate(struct key *key,
struct key_preparsed_payload *prep)
{
struct encrypted_key_payload *epayload = NULL;
char *datablob = NULL;
const char *format = NULL;
char *master_desc = NULL;
char *decrypted_datalen = NULL;
char *hex_encoded_iv = NULL;
size_t datalen = prep->datalen;
int ret;
if (datalen <= 0 || datalen > 32767 || !prep->data)
return -EINVAL;
datablob = kmalloc(datalen + 1, GFP_KERNEL);
if (!datablob)
return -ENOMEM;
datablob[datalen] = 0;
memcpy(datablob, prep->data, datalen);
ret = datablob_parse(datablob, &format, &master_desc,
&decrypted_datalen, &hex_encoded_iv);
if (ret < 0)
goto out;
epayload = encrypted_key_alloc(key, format, master_desc,
decrypted_datalen);
if (IS_ERR(epayload)) {
ret = PTR_ERR(epayload);
goto out;
}
ret = encrypted_init(epayload, key->description, format, master_desc,
decrypted_datalen, hex_encoded_iv);
if (ret < 0) {
kfree(epayload);
goto out;
}
rcu_assign_keypointer(key, epayload);
out:
kfree(datablob);
return ret;
}
static void encrypted_rcu_free(struct rcu_head *rcu)
{
struct encrypted_key_payload *epayload;
epayload = container_of(rcu, struct encrypted_key_payload, rcu);
memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
kfree(epayload);
}
/*
* encrypted_update - update the master key description
*
* Change the master key description for an existing encrypted key.
* The next read will return an encrypted datablob using the new
* master key description.
*
* On success, return 0. Otherwise return errno.
*/
static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
{
struct encrypted_key_payload *epayload = key->payload.data;
struct encrypted_key_payload *new_epayload;
char *buf;
char *new_master_desc = NULL;
const char *format = NULL;
size_t datalen = prep->datalen;
int ret = 0;
if (datalen <= 0 || datalen > 32767 || !prep->data)
return -EINVAL;
buf = kmalloc(datalen + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
buf[datalen] = 0;
memcpy(buf, prep->data, datalen);
ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
if (ret < 0)
goto out;
ret = valid_master_desc(new_master_desc, epayload->master_desc);
if (ret < 0)
goto out;
new_epayload = encrypted_key_alloc(key, epayload->format,
new_master_desc, epayload->datalen);
if (IS_ERR(new_epayload)) {
ret = PTR_ERR(new_epayload);
goto out;
}
__ekey_init(new_epayload, epayload->format, new_master_desc,
epayload->datalen);
memcpy(new_epayload->iv, epayload->iv, ivsize);
memcpy(new_epayload->payload_data, epayload->payload_data,
epayload->payload_datalen);
rcu_assign_keypointer(key, new_epayload);
call_rcu(&epayload->rcu, encrypted_rcu_free);
out:
kfree(buf);
return ret;
}
/*
* encrypted_read - format and copy the encrypted data to userspace
*
* The resulting datablob format is:
* <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
*
* On success, return to userspace the encrypted key datablob size.
*/
static long encrypted_read(const struct key *key, char __user *buffer,
size_t buflen)
{
struct encrypted_key_payload *epayload;
struct key *mkey;
u8 *master_key;
size_t master_keylen;
char derived_key[HASH_SIZE];
char *ascii_buf;
size_t asciiblob_len;
int ret;
epayload = rcu_dereference_key(key);
/* returns the hex encoded iv, encrypted-data, and hmac as ascii */
asciiblob_len = epayload->datablob_len + ivsize + 1
+ roundup(epayload->decrypted_datalen, blksize)
+ (HASH_SIZE * 2);
if (!buffer || buflen < asciiblob_len)
return asciiblob_len;
mkey = request_master_key(epayload, &master_key, &master_keylen);
if (IS_ERR(mkey))
return PTR_ERR(mkey);
ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
if (ret < 0)
goto out;
ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
if (ret < 0)
goto out;
ret = datablob_hmac_append(epayload, master_key, master_keylen);
if (ret < 0)
goto out;
ascii_buf = datablob_format(epayload, asciiblob_len);
if (!ascii_buf) {
ret = -ENOMEM;
goto out;
}
up_read(&mkey->sem);
key_put(mkey);
if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
ret = -EFAULT;
kfree(ascii_buf);
return asciiblob_len;
out:
up_read(&mkey->sem);
key_put(mkey);
return ret;
}
/*
* encrypted_destroy - before freeing the key, clear the decrypted data
*
* Before freeing the key, clear the memory containing the decrypted
* key data.
*/
static void encrypted_destroy(struct key *key)
{
struct encrypted_key_payload *epayload = key->payload.data;
if (!epayload)
return;
memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
kfree(key->payload.data);
}
struct key_type key_type_encrypted = {
.name = "encrypted",
.instantiate = encrypted_instantiate,
.update = encrypted_update,
.destroy = encrypted_destroy,
.describe = user_describe,
.read = encrypted_read,
};
EXPORT_SYMBOL_GPL(key_type_encrypted);
static void encrypted_shash_release(void)
{
if (hashalg)
crypto_free_shash(hashalg);
if (hmacalg)
crypto_free_shash(hmacalg);
}
static int __init encrypted_shash_alloc(void)
{
int ret;
hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(hmacalg)) {
pr_info("encrypted_key: could not allocate crypto %s\n",
hmac_alg);
return PTR_ERR(hmacalg);
}
hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(hashalg)) {
pr_info("encrypted_key: could not allocate crypto %s\n",
hash_alg);
ret = PTR_ERR(hashalg);
goto hashalg_fail;
}
return 0;
hashalg_fail:
crypto_free_shash(hmacalg);
return ret;
}
static int __init init_encrypted(void)
{
int ret;
ret = encrypted_shash_alloc();
if (ret < 0)
return ret;
ret = aes_get_sizes();
if (ret < 0)
goto out;
ret = register_key_type(&key_type_encrypted);
if (ret < 0)
goto out;
return 0;
out:
encrypted_shash_release();
return ret;
}
static void __exit cleanup_encrypted(void)
{
encrypted_shash_release();
unregister_key_type(&key_type_encrypted);
}
late_initcall(init_encrypted);
module_exit(cleanup_encrypted);
MODULE_LICENSE("GPL");