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linux/fs/ecryptfs/keystore.c
Colin Ian King 2a559a8bde eCryptfs: ensure copy to crypt_stat->cipher does not overrun 
The patch 237fead619: "[PATCH] ecryptfs: fs/Makefile and
fs/Kconfig" from Oct 4, 2006, leads to the following static checker
warning:

  fs/ecryptfs/crypto.c:846 ecryptfs_new_file_context()
  error: off-by-one overflow 'crypt_stat->cipher' size 32.  rl = '0-32'

There is a mismatch between the size of ecryptfs_crypt_stat.cipher
and ecryptfs_mount_crypt_stat.global_default_cipher_name causing the
copy of the cipher name to cause a off-by-one string copy error. This
fix ensures the space reserved for this string is the same size including
the trailing zero at the end throughout ecryptfs.

This fix avoids increasing the size of ecryptfs_crypt_stat.cipher
and also ecryptfs_parse_tag_70_packet_silly_stack.cipher_string and instead
reduces the of ECRYPTFS_MAX_CIPHER_NAME_SIZE to 31 and includes the + 1 for
the end of string terminator.

NOTE: An overflow is not possible in practice since the value copied
into global_default_cipher_name is validated by
ecryptfs_code_for_cipher_string() at mount time. None of the allowed
cipher strings are long enough to cause the potential buffer overflow
fixed by this patch.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
[tyhicks: Added the NOTE about the overflow not being triggerable]
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2015-02-24 19:23:28 -06:00

2530 lines
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/**
* eCryptfs: Linux filesystem encryption layer
* In-kernel key management code. Includes functions to parse and
* write authentication token-related packets with the underlying
* file.
*
* Copyright (C) 2004-2006 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
* Michael C. Thompson <mcthomps@us.ibm.com>
* Trevor S. Highland <trevor.highland@gmail.com>
*
* 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; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <linux/string.h>
#include <linux/pagemap.h>
#include <linux/key.h>
#include <linux/random.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include "ecryptfs_kernel.h"
/**
* request_key returned an error instead of a valid key address;
* determine the type of error, make appropriate log entries, and
* return an error code.
*/
static int process_request_key_err(long err_code)
{
int rc = 0;
switch (err_code) {
case -ENOKEY:
ecryptfs_printk(KERN_WARNING, "No key\n");
rc = -ENOENT;
break;
case -EKEYEXPIRED:
ecryptfs_printk(KERN_WARNING, "Key expired\n");
rc = -ETIME;
break;
case -EKEYREVOKED:
ecryptfs_printk(KERN_WARNING, "Key revoked\n");
rc = -EINVAL;
break;
default:
ecryptfs_printk(KERN_WARNING, "Unknown error code: "
"[0x%.16lx]\n", err_code);
rc = -EINVAL;
}
return rc;
}
static int process_find_global_auth_tok_for_sig_err(int err_code)
{
int rc = err_code;
switch (err_code) {
case -ENOENT:
ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
break;
case -EINVAL:
ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
break;
default:
rc = process_request_key_err(err_code);
break;
}
return rc;
}
/**
* ecryptfs_parse_packet_length
* @data: Pointer to memory containing length at offset
* @size: This function writes the decoded size to this memory
* address; zero on error
* @length_size: The number of bytes occupied by the encoded length
*
* Returns zero on success; non-zero on error
*/
int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
size_t *length_size)
{
int rc = 0;
(*length_size) = 0;
(*size) = 0;
if (data[0] < 192) {
/* One-byte length */
(*size) = data[0];
(*length_size) = 1;
} else if (data[0] < 224) {
/* Two-byte length */
(*size) = (data[0] - 192) * 256;
(*size) += data[1] + 192;
(*length_size) = 2;
} else if (data[0] == 255) {
/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
"supported\n");
rc = -EINVAL;
goto out;
} else {
ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
rc = -EINVAL;
goto out;
}
out:
return rc;
}
/**
* ecryptfs_write_packet_length
* @dest: The byte array target into which to write the length. Must
* have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
* @size: The length to write.
* @packet_size_length: The number of bytes used to encode the packet
* length is written to this address.
*
* Returns zero on success; non-zero on error.
*/
int ecryptfs_write_packet_length(char *dest, size_t size,
size_t *packet_size_length)
{
int rc = 0;
if (size < 192) {
dest[0] = size;
(*packet_size_length) = 1;
} else if (size < 65536) {
dest[0] = (((size - 192) / 256) + 192);
dest[1] = ((size - 192) % 256);
(*packet_size_length) = 2;
} else {
/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
rc = -EINVAL;
ecryptfs_printk(KERN_WARNING,
"Unsupported packet size: [%zd]\n", size);
}
return rc;
}
static int
write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
char **packet, size_t *packet_len)
{
size_t i = 0;
size_t data_len;
size_t packet_size_len;
char *message;
int rc;
/*
* ***** TAG 64 Packet Format *****
* | Content Type | 1 byte |
* | Key Identifier Size | 1 or 2 bytes |
* | Key Identifier | arbitrary |
* | Encrypted File Encryption Key Size | 1 or 2 bytes |
* | Encrypted File Encryption Key | arbitrary |
*/
data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
+ session_key->encrypted_key_size);
*packet = kmalloc(data_len, GFP_KERNEL);
message = *packet;
if (!message) {
ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
i += ECRYPTFS_SIG_SIZE_HEX;
rc = ecryptfs_write_packet_length(&message[i],
session_key->encrypted_key_size,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
memcpy(&message[i], session_key->encrypted_key,
session_key->encrypted_key_size);
i += session_key->encrypted_key_size;
*packet_len = i;
out:
return rc;
}
static int
parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
struct ecryptfs_message *msg)
{
size_t i = 0;
char *data;
size_t data_len;
size_t m_size;
size_t message_len;
u16 checksum = 0;
u16 expected_checksum = 0;
int rc;
/*
* ***** TAG 65 Packet Format *****
* | Content Type | 1 byte |
* | Status Indicator | 1 byte |
* | File Encryption Key Size | 1 or 2 bytes |
* | File Encryption Key | arbitrary |
*/
message_len = msg->data_len;
data = msg->data;
if (message_len < 4) {
rc = -EIO;
goto out;
}
if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
rc = -EIO;
goto out;
}
if (data[i++]) {
ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
"[%d]\n", data[i-1]);
rc = -EIO;
goto out;
}
rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
"rc = [%d]\n", rc);
goto out;
}
i += data_len;
if (message_len < (i + m_size)) {
ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
"is shorter than expected\n");
rc = -EIO;
goto out;
}
if (m_size < 3) {
ecryptfs_printk(KERN_ERR,
"The decrypted key is not long enough to "
"include a cipher code and checksum\n");
rc = -EIO;
goto out;
}
*cipher_code = data[i++];
/* The decrypted key includes 1 byte cipher code and 2 byte checksum */
session_key->decrypted_key_size = m_size - 3;
if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
"the maximum key size [%d]\n",
session_key->decrypted_key_size,
ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
rc = -EIO;
goto out;
}
memcpy(session_key->decrypted_key, &data[i],
session_key->decrypted_key_size);
i += session_key->decrypted_key_size;
expected_checksum += (unsigned char)(data[i++]) << 8;
expected_checksum += (unsigned char)(data[i++]);
for (i = 0; i < session_key->decrypted_key_size; i++)
checksum += session_key->decrypted_key[i];
if (expected_checksum != checksum) {
ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
"encryption key; expected [%x]; calculated "
"[%x]\n", expected_checksum, checksum);
rc = -EIO;
}
out:
return rc;
}
static int
write_tag_66_packet(char *signature, u8 cipher_code,
struct ecryptfs_crypt_stat *crypt_stat, char **packet,
size_t *packet_len)
{
size_t i = 0;
size_t j;
size_t data_len;
size_t checksum = 0;
size_t packet_size_len;
char *message;
int rc;
/*
* ***** TAG 66 Packet Format *****
* | Content Type | 1 byte |
* | Key Identifier Size | 1 or 2 bytes |
* | Key Identifier | arbitrary |
* | File Encryption Key Size | 1 or 2 bytes |
* | File Encryption Key | arbitrary |
*/
data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
*packet = kmalloc(data_len, GFP_KERNEL);
message = *packet;
if (!message) {
ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
i += ECRYPTFS_SIG_SIZE_HEX;
/* The encrypted key includes 1 byte cipher code and 2 byte checksum */
rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
&packet_size_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
"header; cannot generate packet length\n");
goto out;
}
i += packet_size_len;
message[i++] = cipher_code;
memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
i += crypt_stat->key_size;
for (j = 0; j < crypt_stat->key_size; j++)
checksum += crypt_stat->key[j];
message[i++] = (checksum / 256) % 256;
message[i++] = (checksum % 256);
*packet_len = i;
out:
return rc;
}
static int
parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
struct ecryptfs_message *msg)
{
size_t i = 0;
char *data;
size_t data_len;
size_t message_len;
int rc;
/*
* ***** TAG 65 Packet Format *****
* | Content Type | 1 byte |
* | Status Indicator | 1 byte |
* | Encrypted File Encryption Key Size | 1 or 2 bytes |
* | Encrypted File Encryption Key | arbitrary |
*/
message_len = msg->data_len;
data = msg->data;
/* verify that everything through the encrypted FEK size is present */
if (message_len < 4) {
rc = -EIO;
printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
"message length is [%d]\n", __func__, message_len, 4);
goto out;
}
if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
rc = -EIO;
printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
__func__);
goto out;
}
if (data[i++]) {
rc = -EIO;
printk(KERN_ERR "%s: Status indicator has non zero "
"value [%d]\n", __func__, data[i-1]);
goto out;
}
rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
&data_len);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
"rc = [%d]\n", rc);
goto out;
}
i += data_len;
if (message_len < (i + key_rec->enc_key_size)) {
rc = -EIO;
printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
__func__, message_len, (i + key_rec->enc_key_size));
goto out;
}
if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
rc = -EIO;
printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
"the maximum key size [%d]\n", __func__,
key_rec->enc_key_size,
ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
goto out;
}
memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
out:
return rc;
}
/**
* ecryptfs_verify_version
* @version: The version number to confirm
*
* Returns zero on good version; non-zero otherwise
*/
static int ecryptfs_verify_version(u16 version)
{
int rc = 0;
unsigned char major;
unsigned char minor;
major = ((version >> 8) & 0xFF);
minor = (version & 0xFF);
if (major != ECRYPTFS_VERSION_MAJOR) {
ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
"Expected [%d]; got [%d]\n",
ECRYPTFS_VERSION_MAJOR, major);
rc = -EINVAL;
goto out;
}
if (minor != ECRYPTFS_VERSION_MINOR) {
ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
"Expected [%d]; got [%d]\n",
ECRYPTFS_VERSION_MINOR, minor);
rc = -EINVAL;
goto out;
}
out:
return rc;
}
/**
* ecryptfs_verify_auth_tok_from_key
* @auth_tok_key: key containing the authentication token
* @auth_tok: authentication token
*
* Returns zero on valid auth tok; -EINVAL otherwise
*/
static int
ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
struct ecryptfs_auth_tok **auth_tok)
{
int rc = 0;
(*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
if (ecryptfs_verify_version((*auth_tok)->version)) {
printk(KERN_ERR "Data structure version mismatch. Userspace "
"tools must match eCryptfs kernel module with major "
"version [%d] and minor version [%d]\n",
ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
rc = -EINVAL;
goto out;
}
if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
&& (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
printk(KERN_ERR "Invalid auth_tok structure "
"returned from key query\n");
rc = -EINVAL;
goto out;
}
out:
return rc;
}
static int
ecryptfs_find_global_auth_tok_for_sig(
struct key **auth_tok_key,
struct ecryptfs_auth_tok **auth_tok,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
{
struct ecryptfs_global_auth_tok *walker;
int rc = 0;
(*auth_tok_key) = NULL;
(*auth_tok) = NULL;
mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
list_for_each_entry(walker,
&mount_crypt_stat->global_auth_tok_list,
mount_crypt_stat_list) {
if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
continue;
if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
rc = -EINVAL;
goto out;
}
rc = key_validate(walker->global_auth_tok_key);
if (rc) {
if (rc == -EKEYEXPIRED)
goto out;
goto out_invalid_auth_tok;
}
down_write(&(walker->global_auth_tok_key->sem));
rc = ecryptfs_verify_auth_tok_from_key(
walker->global_auth_tok_key, auth_tok);
if (rc)
goto out_invalid_auth_tok_unlock;
(*auth_tok_key) = walker->global_auth_tok_key;
key_get(*auth_tok_key);
goto out;
}
rc = -ENOENT;
goto out;
out_invalid_auth_tok_unlock:
up_write(&(walker->global_auth_tok_key->sem));
out_invalid_auth_tok:
printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
key_put(walker->global_auth_tok_key);
walker->global_auth_tok_key = NULL;
out:
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
return rc;
}
/**
* ecryptfs_find_auth_tok_for_sig
* @auth_tok: Set to the matching auth_tok; NULL if not found
* @crypt_stat: inode crypt_stat crypto context
* @sig: Sig of auth_tok to find
*
* For now, this function simply looks at the registered auth_tok's
* linked off the mount_crypt_stat, so all the auth_toks that can be
* used must be registered at mount time. This function could
* potentially try a lot harder to find auth_tok's (e.g., by calling
* out to ecryptfsd to dynamically retrieve an auth_tok object) so
* that static registration of auth_tok's will no longer be necessary.
*
* Returns zero on no error; non-zero on error
*/
static int
ecryptfs_find_auth_tok_for_sig(
struct key **auth_tok_key,
struct ecryptfs_auth_tok **auth_tok,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *sig)
{
int rc = 0;
rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
mount_crypt_stat, sig);
if (rc == -ENOENT) {
/* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
* mount_crypt_stat structure, we prevent to use auth toks that
* are not inserted through the ecryptfs_add_global_auth_tok
* function.
*/
if (mount_crypt_stat->flags
& ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
return -EINVAL;
rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
sig);
}
return rc;
}
/**
* write_tag_70_packet can gobble a lot of stack space. We stuff most
* of the function's parameters in a kmalloc'd struct to help reduce
* eCryptfs' overall stack usage.
*/
struct ecryptfs_write_tag_70_packet_silly_stack {
u8 cipher_code;
size_t max_packet_size;
size_t packet_size_len;
size_t block_aligned_filename_size;
size_t block_size;
size_t i;
size_t j;
size_t num_rand_bytes;
struct mutex *tfm_mutex;
char *block_aligned_filename;
struct ecryptfs_auth_tok *auth_tok;
struct scatterlist src_sg[2];
struct scatterlist dst_sg[2];
struct blkcipher_desc desc;
char iv[ECRYPTFS_MAX_IV_BYTES];
char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
struct hash_desc hash_desc;
struct scatterlist hash_sg;
};
/**
* write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
* @filename: NULL-terminated filename string
*
* This is the simplest mechanism for achieving filename encryption in
* eCryptfs. It encrypts the given filename with the mount-wide
* filename encryption key (FNEK) and stores it in a packet to @dest,
* which the callee will encode and write directly into the dentry
* name.
*/
int
ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
size_t *packet_size,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *filename, size_t filename_size)
{
struct ecryptfs_write_tag_70_packet_silly_stack *s;
struct key *auth_tok_key = NULL;
int rc = 0;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s) {
printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
"[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
rc = -ENOMEM;
goto out;
}
s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
(*packet_size) = 0;
rc = ecryptfs_find_auth_tok_for_sig(
&auth_tok_key,
&s->auth_tok, mount_crypt_stat,
mount_crypt_stat->global_default_fnek_sig);
if (rc) {
printk(KERN_ERR "%s: Error attempting to find auth tok for "
"fnek sig [%s]; rc = [%d]\n", __func__,
mount_crypt_stat->global_default_fnek_sig, rc);
goto out;
}
rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
&s->desc.tfm,
&s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
if (unlikely(rc)) {
printk(KERN_ERR "Internal error whilst attempting to get "
"tfm and mutex for cipher name [%s]; rc = [%d]\n",
mount_crypt_stat->global_default_fn_cipher_name, rc);
goto out;
}
mutex_lock(s->tfm_mutex);
s->block_size = crypto_blkcipher_blocksize(s->desc.tfm);
/* Plus one for the \0 separator between the random prefix
* and the plaintext filename */
s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
if ((s->block_aligned_filename_size % s->block_size) != 0) {
s->num_rand_bytes += (s->block_size
- (s->block_aligned_filename_size
% s->block_size));
s->block_aligned_filename_size = (s->num_rand_bytes
+ filename_size);
}
/* Octet 0: Tag 70 identifier
* Octets 1-N1: Tag 70 packet size (includes cipher identifier
* and block-aligned encrypted filename size)
* Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
* Octet N2-N3: Cipher identifier (1 octet)
* Octets N3-N4: Block-aligned encrypted filename
* - Consists of a minimum number of random characters, a \0
* separator, and then the filename */
s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
+ s->block_aligned_filename_size);
if (dest == NULL) {
(*packet_size) = s->max_packet_size;
goto out_unlock;
}
if (s->max_packet_size > (*remaining_bytes)) {
printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
"[%zd] available\n", __func__, s->max_packet_size,
(*remaining_bytes));
rc = -EINVAL;
goto out_unlock;
}
s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
GFP_KERNEL);
if (!s->block_aligned_filename) {
printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
"kzalloc [%zd] bytes\n", __func__,
s->block_aligned_filename_size);
rc = -ENOMEM;
goto out_unlock;
}
s->i = 0;
dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&dest[s->i],
(ECRYPTFS_SIG_SIZE
+ 1 /* Cipher code */
+ s->block_aligned_filename_size),
&s->packet_size_len);
if (rc) {
printk(KERN_ERR "%s: Error generating tag 70 packet "
"header; cannot generate packet length; rc = [%d]\n",
__func__, rc);
goto out_free_unlock;
}
s->i += s->packet_size_len;
ecryptfs_from_hex(&dest[s->i],
mount_crypt_stat->global_default_fnek_sig,
ECRYPTFS_SIG_SIZE);
s->i += ECRYPTFS_SIG_SIZE;
s->cipher_code = ecryptfs_code_for_cipher_string(
mount_crypt_stat->global_default_fn_cipher_name,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
if (s->cipher_code == 0) {
printk(KERN_WARNING "%s: Unable to generate code for "
"cipher [%s] with key bytes [%zd]\n", __func__,
mount_crypt_stat->global_default_fn_cipher_name,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
rc = -EINVAL;
goto out_free_unlock;
}
dest[s->i++] = s->cipher_code;
/* TODO: Support other key modules than passphrase for
* filename encryption */
if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
rc = -EOPNOTSUPP;
printk(KERN_INFO "%s: Filename encryption only supports "
"password tokens\n", __func__);
goto out_free_unlock;
}
sg_init_one(
&s->hash_sg,
(u8 *)s->auth_tok->token.password.session_key_encryption_key,
s->auth_tok->token.password.session_key_encryption_key_bytes);
s->hash_desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
s->hash_desc.tfm = crypto_alloc_hash(ECRYPTFS_TAG_70_DIGEST, 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(s->hash_desc.tfm)) {
rc = PTR_ERR(s->hash_desc.tfm);
printk(KERN_ERR "%s: Error attempting to "
"allocate hash crypto context; rc = [%d]\n",
__func__, rc);
goto out_free_unlock;
}
rc = crypto_hash_init(&s->hash_desc);
if (rc) {
printk(KERN_ERR
"%s: Error initializing crypto hash; rc = [%d]\n",
__func__, rc);
goto out_release_free_unlock;
}
rc = crypto_hash_update(
&s->hash_desc, &s->hash_sg,
s->auth_tok->token.password.session_key_encryption_key_bytes);
if (rc) {
printk(KERN_ERR
"%s: Error updating crypto hash; rc = [%d]\n",
__func__, rc);
goto out_release_free_unlock;
}
rc = crypto_hash_final(&s->hash_desc, s->hash);
if (rc) {
printk(KERN_ERR
"%s: Error finalizing crypto hash; rc = [%d]\n",
__func__, rc);
goto out_release_free_unlock;
}
for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
s->block_aligned_filename[s->j] =
s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
== (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
sg_init_one(&s->hash_sg, (u8 *)s->hash,
ECRYPTFS_TAG_70_DIGEST_SIZE);
rc = crypto_hash_init(&s->hash_desc);
if (rc) {
printk(KERN_ERR
"%s: Error initializing crypto hash; "
"rc = [%d]\n", __func__, rc);
goto out_release_free_unlock;
}
rc = crypto_hash_update(&s->hash_desc, &s->hash_sg,
ECRYPTFS_TAG_70_DIGEST_SIZE);
if (rc) {
printk(KERN_ERR
"%s: Error updating crypto hash; "
"rc = [%d]\n", __func__, rc);
goto out_release_free_unlock;
}
rc = crypto_hash_final(&s->hash_desc, s->tmp_hash);
if (rc) {
printk(KERN_ERR
"%s: Error finalizing crypto hash; "
"rc = [%d]\n", __func__, rc);
goto out_release_free_unlock;
}
memcpy(s->hash, s->tmp_hash,
ECRYPTFS_TAG_70_DIGEST_SIZE);
}
if (s->block_aligned_filename[s->j] == '\0')
s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
}
memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
filename_size);
rc = virt_to_scatterlist(s->block_aligned_filename,
s->block_aligned_filename_size, s->src_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert filename memory to scatterlist; rc = [%d]. "
"block_aligned_filename_size = [%zd]\n", __func__, rc,
s->block_aligned_filename_size);
goto out_release_free_unlock;
}
rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
s->dst_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert encrypted filename memory to scatterlist; "
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);
goto out_release_free_unlock;
}
/* The characters in the first block effectively do the job
* of the IV here, so we just use 0's for the IV. Note the
* constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
* >= ECRYPTFS_MAX_IV_BYTES. */
memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
s->desc.info = s->iv;
rc = crypto_blkcipher_setkey(
s->desc.tfm,
s->auth_tok->token.password.session_key_encryption_key,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
if (rc < 0) {
printk(KERN_ERR "%s: Error setting key for crypto context; "
"rc = [%d]. s->auth_tok->token.password.session_key_"
"encryption_key = [0x%p]; mount_crypt_stat->"
"global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
rc,
s->auth_tok->token.password.session_key_encryption_key,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
goto out_release_free_unlock;
}
rc = crypto_blkcipher_encrypt_iv(&s->desc, s->dst_sg, s->src_sg,
s->block_aligned_filename_size);
if (rc) {
printk(KERN_ERR "%s: Error attempting to encrypt filename; "
"rc = [%d]\n", __func__, rc);
goto out_release_free_unlock;
}
s->i += s->block_aligned_filename_size;
(*packet_size) = s->i;
(*remaining_bytes) -= (*packet_size);
out_release_free_unlock:
crypto_free_hash(s->hash_desc.tfm);
out_free_unlock:
kzfree(s->block_aligned_filename);
out_unlock:
mutex_unlock(s->tfm_mutex);
out:
if (auth_tok_key) {
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
}
kfree(s);
return rc;
}
struct ecryptfs_parse_tag_70_packet_silly_stack {
u8 cipher_code;
size_t max_packet_size;
size_t packet_size_len;
size_t parsed_tag_70_packet_size;
size_t block_aligned_filename_size;
size_t block_size;
size_t i;
struct mutex *tfm_mutex;
char *decrypted_filename;
struct ecryptfs_auth_tok *auth_tok;
struct scatterlist src_sg[2];
struct scatterlist dst_sg[2];
struct blkcipher_desc desc;
char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
char iv[ECRYPTFS_MAX_IV_BYTES];
char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
};
/**
* parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
* @filename: This function kmalloc's the memory for the filename
* @filename_size: This function sets this to the amount of memory
* kmalloc'd for the filename
* @packet_size: This function sets this to the the number of octets
* in the packet parsed
* @mount_crypt_stat: The mount-wide cryptographic context
* @data: The memory location containing the start of the tag 70
* packet
* @max_packet_size: The maximum legal size of the packet to be parsed
* from @data
*
* Returns zero on success; non-zero otherwise
*/
int
ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
size_t *packet_size,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *data, size_t max_packet_size)
{
struct ecryptfs_parse_tag_70_packet_silly_stack *s;
struct key *auth_tok_key = NULL;
int rc = 0;
(*packet_size) = 0;
(*filename_size) = 0;
(*filename) = NULL;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s) {
printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
"[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
rc = -ENOMEM;
goto out;
}
s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
"at least [%d]\n", __func__, max_packet_size,
ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
rc = -EINVAL;
goto out;
}
/* Octet 0: Tag 70 identifier
* Octets 1-N1: Tag 70 packet size (includes cipher identifier
* and block-aligned encrypted filename size)
* Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
* Octet N2-N3: Cipher identifier (1 octet)
* Octets N3-N4: Block-aligned encrypted filename
* - Consists of a minimum number of random numbers, a \0
* separator, and then the filename */
if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
"tag [0x%.2x]\n", __func__,
data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
rc = -EINVAL;
goto out;
}
rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
&s->parsed_tag_70_packet_size,
&s->packet_size_len);
if (rc) {
printk(KERN_WARNING "%s: Error parsing packet length; "
"rc = [%d]\n", __func__, rc);
goto out;
}
s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
- ECRYPTFS_SIG_SIZE - 1);
if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
> max_packet_size) {
printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
"size is [%zd]\n", __func__, max_packet_size,
(1 + s->packet_size_len + 1
+ s->block_aligned_filename_size));
rc = -EINVAL;
goto out;
}
(*packet_size) += s->packet_size_len;
ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
ECRYPTFS_SIG_SIZE);
s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
(*packet_size) += ECRYPTFS_SIG_SIZE;
s->cipher_code = data[(*packet_size)++];
rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
if (rc) {
printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
__func__, s->cipher_code);
goto out;
}
rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
&s->auth_tok, mount_crypt_stat,
s->fnek_sig_hex);
if (rc) {
printk(KERN_ERR "%s: Error attempting to find auth tok for "
"fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
rc);
goto out;
}
rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->desc.tfm,
&s->tfm_mutex,
s->cipher_string);
if (unlikely(rc)) {
printk(KERN_ERR "Internal error whilst attempting to get "
"tfm and mutex for cipher name [%s]; rc = [%d]\n",
s->cipher_string, rc);
goto out;
}
mutex_lock(s->tfm_mutex);
rc = virt_to_scatterlist(&data[(*packet_size)],
s->block_aligned_filename_size, s->src_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert encrypted filename memory to scatterlist; "
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);
goto out_unlock;
}
(*packet_size) += s->block_aligned_filename_size;
s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
GFP_KERNEL);
if (!s->decrypted_filename) {
printk(KERN_ERR "%s: Out of memory whilst attempting to "
"kmalloc [%zd] bytes\n", __func__,
s->block_aligned_filename_size);
rc = -ENOMEM;
goto out_unlock;
}
rc = virt_to_scatterlist(s->decrypted_filename,
s->block_aligned_filename_size, s->dst_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert decrypted filename memory to scatterlist; "
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);
goto out_free_unlock;
}
/* The characters in the first block effectively do the job of
* the IV here, so we just use 0's for the IV. Note the
* constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
* >= ECRYPTFS_MAX_IV_BYTES. */
memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
s->desc.info = s->iv;
/* TODO: Support other key modules than passphrase for
* filename encryption */
if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
rc = -EOPNOTSUPP;
printk(KERN_INFO "%s: Filename encryption only supports "
"password tokens\n", __func__);
goto out_free_unlock;
}
rc = crypto_blkcipher_setkey(
s->desc.tfm,
s->auth_tok->token.password.session_key_encryption_key,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
if (rc < 0) {
printk(KERN_ERR "%s: Error setting key for crypto context; "
"rc = [%d]. s->auth_tok->token.password.session_key_"
"encryption_key = [0x%p]; mount_crypt_stat->"
"global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
rc,
s->auth_tok->token.password.session_key_encryption_key,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
goto out_free_unlock;
}
rc = crypto_blkcipher_decrypt_iv(&s->desc, s->dst_sg, s->src_sg,
s->block_aligned_filename_size);
if (rc) {
printk(KERN_ERR "%s: Error attempting to decrypt filename; "
"rc = [%d]\n", __func__, rc);
goto out_free_unlock;
}
s->i = 0;
while (s->decrypted_filename[s->i] != '\0'
&& s->i < s->block_aligned_filename_size)
s->i++;
if (s->i == s->block_aligned_filename_size) {
printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
"find valid separator between random characters and "
"the filename\n", __func__);
rc = -EINVAL;
goto out_free_unlock;
}
s->i++;
(*filename_size) = (s->block_aligned_filename_size - s->i);
if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
printk(KERN_WARNING "%s: Filename size is [%zd], which is "
"invalid\n", __func__, (*filename_size));
rc = -EINVAL;
goto out_free_unlock;
}
(*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
if (!(*filename)) {
printk(KERN_ERR "%s: Out of memory whilst attempting to "
"kmalloc [%zd] bytes\n", __func__,
((*filename_size) + 1));
rc = -ENOMEM;
goto out_free_unlock;
}
memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
(*filename)[(*filename_size)] = '\0';
out_free_unlock:
kfree(s->decrypted_filename);
out_unlock:
mutex_unlock(s->tfm_mutex);
out:
if (rc) {
(*packet_size) = 0;
(*filename_size) = 0;
(*filename) = NULL;
}
if (auth_tok_key) {
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
}
kfree(s);
return rc;
}
static int
ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
{
int rc = 0;
(*sig) = NULL;
switch (auth_tok->token_type) {
case ECRYPTFS_PASSWORD:
(*sig) = auth_tok->token.password.signature;
break;
case ECRYPTFS_PRIVATE_KEY:
(*sig) = auth_tok->token.private_key.signature;
break;
default:
printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
auth_tok->token_type);
rc = -EINVAL;
}
return rc;
}
/**
* decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
* @auth_tok: The key authentication token used to decrypt the session key
* @crypt_stat: The cryptographic context
*
* Returns zero on success; non-zero error otherwise.
*/
static int
decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat)
{
u8 cipher_code = 0;
struct ecryptfs_msg_ctx *msg_ctx;
struct ecryptfs_message *msg = NULL;
char *auth_tok_sig;
char *payload = NULL;
size_t payload_len = 0;
int rc;
rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
if (rc) {
printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
auth_tok->token_type);
goto out;
}
rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
&payload, &payload_len);
if (rc) {
ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
goto out;
}
rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error sending message to "
"ecryptfsd: %d\n", rc);
goto out;
}
rc = ecryptfs_wait_for_response(msg_ctx, &msg);
if (rc) {
ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
"from the user space daemon\n");
rc = -EIO;
goto out;
}
rc = parse_tag_65_packet(&(auth_tok->session_key),
&cipher_code, msg);
if (rc) {
printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
rc);
goto out;
}
auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
auth_tok->session_key.decrypted_key_size);
crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
if (rc) {
ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
cipher_code)
goto out;
}
crypt_stat->flags |= ECRYPTFS_KEY_VALID;
if (ecryptfs_verbosity > 0) {
ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
ecryptfs_dump_hex(crypt_stat->key,
crypt_stat->key_size);
}
out:
kfree(msg);
kfree(payload);
return rc;
}
static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
{
struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
auth_tok_list_head, list) {
list_del(&auth_tok_list_item->list);
kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
auth_tok_list_item);
}
}
struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
/**
* parse_tag_1_packet
* @crypt_stat: The cryptographic context to modify based on packet contents
* @data: The raw bytes of the packet.
* @auth_tok_list: eCryptfs parses packets into authentication tokens;
* a new authentication token will be placed at the
* end of this list for this packet.
* @new_auth_tok: Pointer to a pointer to memory that this function
* allocates; sets the memory address of the pointer to
* NULL on error. This object is added to the
* auth_tok_list.
* @packet_size: This function writes the size of the parsed packet
* into this memory location; zero on error.
* @max_packet_size: The maximum allowable packet size
*
* Returns zero on success; non-zero on error.
*/
static int
parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
unsigned char *data, struct list_head *auth_tok_list,
struct ecryptfs_auth_tok **new_auth_tok,
size_t *packet_size, size_t max_packet_size)
{
size_t body_size;
struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
size_t length_size;
int rc = 0;
(*packet_size) = 0;
(*new_auth_tok) = NULL;
/**
* This format is inspired by OpenPGP; see RFC 2440
* packet tag 1
*
* Tag 1 identifier (1 byte)
* Max Tag 1 packet size (max 3 bytes)
* Version (1 byte)
* Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
* Cipher identifier (1 byte)
* Encrypted key size (arbitrary)
*
* 12 bytes minimum packet size
*/
if (unlikely(max_packet_size < 12)) {
printk(KERN_ERR "Invalid max packet size; must be >=12\n");
rc = -EINVAL;
goto out;
}
if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
ECRYPTFS_TAG_1_PACKET_TYPE);
rc = -EINVAL;
goto out;
}
/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
* at end of function upon failure */
auth_tok_list_item =
kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
GFP_KERNEL);
if (!auth_tok_list_item) {
printk(KERN_ERR "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
(*new_auth_tok) = &auth_tok_list_item->auth_tok;
rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
&length_size);
if (rc) {
printk(KERN_WARNING "Error parsing packet length; "
"rc = [%d]\n", rc);
goto out_free;
}
if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
rc = -EINVAL;
goto out_free;
}
(*packet_size) += length_size;
if (unlikely((*packet_size) + body_size > max_packet_size)) {
printk(KERN_WARNING "Packet size exceeds max\n");
rc = -EINVAL;
goto out_free;
}
if (unlikely(data[(*packet_size)++] != 0x03)) {
printk(KERN_WARNING "Unknown version number [%d]\n",
data[(*packet_size) - 1]);
rc = -EINVAL;
goto out_free;
}
ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
&data[(*packet_size)], ECRYPTFS_SIG_SIZE);
*packet_size += ECRYPTFS_SIG_SIZE;
/* This byte is skipped because the kernel does not need to
* know which public key encryption algorithm was used */
(*packet_size)++;
(*new_auth_tok)->session_key.encrypted_key_size =
body_size - (ECRYPTFS_SIG_SIZE + 2);
if ((*new_auth_tok)->session_key.encrypted_key_size
> ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
printk(KERN_WARNING "Tag 1 packet contains key larger "
"than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
rc = -EINVAL;
goto out;
}
memcpy((*new_auth_tok)->session_key.encrypted_key,
&data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
(*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
(*new_auth_tok)->session_key.flags &=
~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
(*new_auth_tok)->session_key.flags |=
ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
(*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
(*new_auth_tok)->flags = 0;
(*new_auth_tok)->session_key.flags &=
~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
(*new_auth_tok)->session_key.flags &=
~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
list_add(&auth_tok_list_item->list, auth_tok_list);
goto out;
out_free:
(*new_auth_tok) = NULL;
memset(auth_tok_list_item, 0,
sizeof(struct ecryptfs_auth_tok_list_item));
kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
auth_tok_list_item);
out:
if (rc)
(*packet_size) = 0;
return rc;
}
/**
* parse_tag_3_packet
* @crypt_stat: The cryptographic context to modify based on packet
* contents.
* @data: The raw bytes of the packet.
* @auth_tok_list: eCryptfs parses packets into authentication tokens;
* a new authentication token will be placed at the end
* of this list for this packet.
* @new_auth_tok: Pointer to a pointer to memory that this function
* allocates; sets the memory address of the pointer to
* NULL on error. This object is added to the
* auth_tok_list.
* @packet_size: This function writes the size of the parsed packet
* into this memory location; zero on error.
* @max_packet_size: maximum number of bytes to parse
*
* Returns zero on success; non-zero on error.
*/
static int
parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
unsigned char *data, struct list_head *auth_tok_list,
struct ecryptfs_auth_tok **new_auth_tok,
size_t *packet_size, size_t max_packet_size)
{
size_t body_size;
struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
size_t length_size;
int rc = 0;
(*packet_size) = 0;
(*new_auth_tok) = NULL;
/**
*This format is inspired by OpenPGP; see RFC 2440
* packet tag 3
*
* Tag 3 identifier (1 byte)
* Max Tag 3 packet size (max 3 bytes)
* Version (1 byte)
* Cipher code (1 byte)
* S2K specifier (1 byte)
* Hash identifier (1 byte)
* Salt (ECRYPTFS_SALT_SIZE)
* Hash iterations (1 byte)
* Encrypted key (arbitrary)
*
* (ECRYPTFS_SALT_SIZE + 7) minimum packet size
*/
if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
printk(KERN_ERR "Max packet size too large\n");
rc = -EINVAL;
goto out;
}
if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
ECRYPTFS_TAG_3_PACKET_TYPE);
rc = -EINVAL;
goto out;
}
/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
* at end of function upon failure */
auth_tok_list_item =
kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
if (!auth_tok_list_item) {
printk(KERN_ERR "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
(*new_auth_tok) = &auth_tok_list_item->auth_tok;
rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
&length_size);
if (rc) {
printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
rc);
goto out_free;
}
if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
rc = -EINVAL;
goto out_free;
}
(*packet_size) += length_size;
if (unlikely((*packet_size) + body_size > max_packet_size)) {
printk(KERN_ERR "Packet size exceeds max\n");
rc = -EINVAL;
goto out_free;
}
(*new_auth_tok)->session_key.encrypted_key_size =
(body_size - (ECRYPTFS_SALT_SIZE + 5));
if ((*new_auth_tok)->session_key.encrypted_key_size
> ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
printk(KERN_WARNING "Tag 3 packet contains key larger "
"than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
rc = -EINVAL;
goto out_free;
}
if (unlikely(data[(*packet_size)++] != 0x04)) {
printk(KERN_WARNING "Unknown version number [%d]\n",
data[(*packet_size) - 1]);
rc = -EINVAL;
goto out_free;
}
rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
(u16)data[(*packet_size)]);
if (rc)
goto out_free;
/* A little extra work to differentiate among the AES key
* sizes; see RFC2440 */
switch(data[(*packet_size)++]) {
case RFC2440_CIPHER_AES_192:
crypt_stat->key_size = 24;
break;
default:
crypt_stat->key_size =
(*new_auth_tok)->session_key.encrypted_key_size;
}
rc = ecryptfs_init_crypt_ctx(crypt_stat);
if (rc)
goto out_free;
if (unlikely(data[(*packet_size)++] != 0x03)) {
printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
rc = -ENOSYS;
goto out_free;
}
/* TODO: finish the hash mapping */
switch (data[(*packet_size)++]) {
case 0x01: /* See RFC2440 for these numbers and their mappings */
/* Choose MD5 */
memcpy((*new_auth_tok)->token.password.salt,
&data[(*packet_size)], ECRYPTFS_SALT_SIZE);
(*packet_size) += ECRYPTFS_SALT_SIZE;
/* This conversion was taken straight from RFC2440 */
(*new_auth_tok)->token.password.hash_iterations =
((u32) 16 + (data[(*packet_size)] & 15))
<< ((data[(*packet_size)] >> 4) + 6);
(*packet_size)++;
/* Friendly reminder:
* (*new_auth_tok)->session_key.encrypted_key_size =
* (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
memcpy((*new_auth_tok)->session_key.encrypted_key,
&data[(*packet_size)],
(*new_auth_tok)->session_key.encrypted_key_size);
(*packet_size) +=
(*new_auth_tok)->session_key.encrypted_key_size;
(*new_auth_tok)->session_key.flags &=
~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
(*new_auth_tok)->session_key.flags |=
ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
(*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
break;
default:
ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
"[%d]\n", data[(*packet_size) - 1]);
rc = -ENOSYS;
goto out_free;
}
(*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
/* TODO: Parametarize; we might actually want userspace to
* decrypt the session key. */
(*new_auth_tok)->session_key.flags &=
~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
(*new_auth_tok)->session_key.flags &=
~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
list_add(&auth_tok_list_item->list, auth_tok_list);
goto out;
out_free:
(*new_auth_tok) = NULL;
memset(auth_tok_list_item, 0,
sizeof(struct ecryptfs_auth_tok_list_item));
kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
auth_tok_list_item);
out:
if (rc)
(*packet_size) = 0;
return rc;
}
/**
* parse_tag_11_packet
* @data: The raw bytes of the packet
* @contents: This function writes the data contents of the literal
* packet into this memory location
* @max_contents_bytes: The maximum number of bytes that this function
* is allowed to write into contents
* @tag_11_contents_size: This function writes the size of the parsed
* contents into this memory location; zero on
* error
* @packet_size: This function writes the size of the parsed packet
* into this memory location; zero on error
* @max_packet_size: maximum number of bytes to parse
*
* Returns zero on success; non-zero on error.
*/
static int
parse_tag_11_packet(unsigned char *data, unsigned char *contents,
size_t max_contents_bytes, size_t *tag_11_contents_size,
size_t *packet_size, size_t max_packet_size)
{
size_t body_size;
size_t length_size;
int rc = 0;
(*packet_size) = 0;
(*tag_11_contents_size) = 0;
/* This format is inspired by OpenPGP; see RFC 2440
* packet tag 11
*
* Tag 11 identifier (1 byte)
* Max Tag 11 packet size (max 3 bytes)
* Binary format specifier (1 byte)
* Filename length (1 byte)
* Filename ("_CONSOLE") (8 bytes)
* Modification date (4 bytes)
* Literal data (arbitrary)
*
* We need at least 16 bytes of data for the packet to even be
* valid.
*/
if (max_packet_size < 16) {
printk(KERN_ERR "Maximum packet size too small\n");
rc = -EINVAL;
goto out;
}
if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
printk(KERN_WARNING "Invalid tag 11 packet format\n");
rc = -EINVAL;
goto out;
}
rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
&length_size);
if (rc) {
printk(KERN_WARNING "Invalid tag 11 packet format\n");
goto out;
}
if (body_size < 14) {
printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
rc = -EINVAL;
goto out;
}
(*packet_size) += length_size;
(*tag_11_contents_size) = (body_size - 14);
if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
printk(KERN_ERR "Packet size exceeds max\n");
rc = -EINVAL;
goto out;
}
if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
"expected size\n");
rc = -EINVAL;
goto out;
}
if (data[(*packet_size)++] != 0x62) {
printk(KERN_WARNING "Unrecognizable packet\n");
rc = -EINVAL;
goto out;
}
if (data[(*packet_size)++] != 0x08) {
printk(KERN_WARNING "Unrecognizable packet\n");
rc = -EINVAL;
goto out;
}
(*packet_size) += 12; /* Ignore filename and modification date */
memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
(*packet_size) += (*tag_11_contents_size);
out:
if (rc) {
(*packet_size) = 0;
(*tag_11_contents_size) = 0;
}
return rc;
}
int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
struct ecryptfs_auth_tok **auth_tok,
char *sig)
{
int rc = 0;
(*auth_tok_key) = request_key(&key_type_user, sig, NULL);
if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
(*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
printk(KERN_ERR "Could not find key with description: [%s]\n",
sig);
rc = process_request_key_err(PTR_ERR(*auth_tok_key));
(*auth_tok_key) = NULL;
goto out;
}
}
down_write(&(*auth_tok_key)->sem);
rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
if (rc) {
up_write(&(*auth_tok_key)->sem);
key_put(*auth_tok_key);
(*auth_tok_key) = NULL;
goto out;
}
out:
return rc;
}
/**
* decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
* @auth_tok: The passphrase authentication token to use to encrypt the FEK
* @crypt_stat: The cryptographic context
*
* Returns zero on success; non-zero error otherwise
*/
static int
decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat)
{
struct scatterlist dst_sg[2];
struct scatterlist src_sg[2];
struct mutex *tfm_mutex;
struct blkcipher_desc desc = {
.flags = CRYPTO_TFM_REQ_MAY_SLEEP
};
int rc = 0;
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(
KERN_DEBUG, "Session key encryption key (size [%d]):\n",
auth_tok->token.password.session_key_encryption_key_bytes);
ecryptfs_dump_hex(
auth_tok->token.password.session_key_encryption_key,
auth_tok->token.password.session_key_encryption_key_bytes);
}
rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
crypt_stat->cipher);
if (unlikely(rc)) {
printk(KERN_ERR "Internal error whilst attempting to get "
"tfm and mutex for cipher name [%s]; rc = [%d]\n",
crypt_stat->cipher, rc);
goto out;
}
rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
auth_tok->session_key.encrypted_key_size,
src_sg, 2);
if (rc < 1 || rc > 2) {
printk(KERN_ERR "Internal error whilst attempting to convert "
"auth_tok->session_key.encrypted_key to scatterlist; "
"expected rc = 1; got rc = [%d]. "
"auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
auth_tok->session_key.encrypted_key_size);
goto out;
}
auth_tok->session_key.decrypted_key_size =
auth_tok->session_key.encrypted_key_size;
rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
auth_tok->session_key.decrypted_key_size,
dst_sg, 2);
if (rc < 1 || rc > 2) {
printk(KERN_ERR "Internal error whilst attempting to convert "
"auth_tok->session_key.decrypted_key to scatterlist; "
"expected rc = 1; got rc = [%d]\n", rc);
goto out;
}
mutex_lock(tfm_mutex);
rc = crypto_blkcipher_setkey(
desc.tfm, auth_tok->token.password.session_key_encryption_key,
crypt_stat->key_size);
if (unlikely(rc < 0)) {
mutex_unlock(tfm_mutex);
printk(KERN_ERR "Error setting key for crypto context\n");
rc = -EINVAL;
goto out;
}
rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg,
auth_tok->session_key.encrypted_key_size);
mutex_unlock(tfm_mutex);
if (unlikely(rc)) {
printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
goto out;
}
auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
auth_tok->session_key.decrypted_key_size);
crypt_stat->flags |= ECRYPTFS_KEY_VALID;
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
crypt_stat->key_size);
ecryptfs_dump_hex(crypt_stat->key,
crypt_stat->key_size);
}
out:
return rc;
}
/**
* ecryptfs_parse_packet_set
* @crypt_stat: The cryptographic context
* @src: Virtual address of region of memory containing the packets
* @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
*
* Get crypt_stat to have the file's session key if the requisite key
* is available to decrypt the session key.
*
* Returns Zero if a valid authentication token was retrieved and
* processed; negative value for file not encrypted or for error
* conditions.
*/
int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
unsigned char *src,
struct dentry *ecryptfs_dentry)
{
size_t i = 0;
size_t found_auth_tok;
size_t next_packet_is_auth_tok_packet;
struct list_head auth_tok_list;
struct ecryptfs_auth_tok *matching_auth_tok;
struct ecryptfs_auth_tok *candidate_auth_tok;
char *candidate_auth_tok_sig;
size_t packet_size;
struct ecryptfs_auth_tok *new_auth_tok;
unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
size_t tag_11_contents_size;
size_t tag_11_packet_size;
struct key *auth_tok_key = NULL;
int rc = 0;
INIT_LIST_HEAD(&auth_tok_list);
/* Parse the header to find as many packets as we can; these will be
* added the our &auth_tok_list */
next_packet_is_auth_tok_packet = 1;
while (next_packet_is_auth_tok_packet) {
size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
switch (src[i]) {
case ECRYPTFS_TAG_3_PACKET_TYPE:
rc = parse_tag_3_packet(crypt_stat,
(unsigned char *)&src[i],
&auth_tok_list, &new_auth_tok,
&packet_size, max_packet_size);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error parsing "
"tag 3 packet\n");
rc = -EIO;
goto out_wipe_list;
}
i += packet_size;
rc = parse_tag_11_packet((unsigned char *)&src[i],
sig_tmp_space,
ECRYPTFS_SIG_SIZE,
&tag_11_contents_size,
&tag_11_packet_size,
max_packet_size);
if (rc) {
ecryptfs_printk(KERN_ERR, "No valid "
"(ecryptfs-specific) literal "
"packet containing "
"authentication token "
"signature found after "
"tag 3 packet\n");
rc = -EIO;
goto out_wipe_list;
}
i += tag_11_packet_size;
if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
ecryptfs_printk(KERN_ERR, "Expected "
"signature of size [%d]; "
"read size [%zd]\n",
ECRYPTFS_SIG_SIZE,
tag_11_contents_size);
rc = -EIO;
goto out_wipe_list;
}
ecryptfs_to_hex(new_auth_tok->token.password.signature,
sig_tmp_space, tag_11_contents_size);
new_auth_tok->token.password.signature[
ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
break;
case ECRYPTFS_TAG_1_PACKET_TYPE:
rc = parse_tag_1_packet(crypt_stat,
(unsigned char *)&src[i],
&auth_tok_list, &new_auth_tok,
&packet_size, max_packet_size);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error parsing "
"tag 1 packet\n");
rc = -EIO;
goto out_wipe_list;
}
i += packet_size;
crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
break;
case ECRYPTFS_TAG_11_PACKET_TYPE:
ecryptfs_printk(KERN_WARNING, "Invalid packet set "
"(Tag 11 not allowed by itself)\n");
rc = -EIO;
goto out_wipe_list;
default:
ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
"of the file header; hex value of "
"character is [0x%.2x]\n", i, src[i]);
next_packet_is_auth_tok_packet = 0;
}
}
if (list_empty(&auth_tok_list)) {
printk(KERN_ERR "The lower file appears to be a non-encrypted "
"eCryptfs file; this is not supported in this version "
"of the eCryptfs kernel module\n");
rc = -EINVAL;
goto out;
}
/* auth_tok_list contains the set of authentication tokens
* parsed from the metadata. We need to find a matching
* authentication token that has the secret component(s)
* necessary to decrypt the EFEK in the auth_tok parsed from
* the metadata. There may be several potential matches, but
* just one will be sufficient to decrypt to get the FEK. */
find_next_matching_auth_tok:
found_auth_tok = 0;
list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
candidate_auth_tok = &auth_tok_list_item->auth_tok;
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG,
"Considering cadidate auth tok:\n");
ecryptfs_dump_auth_tok(candidate_auth_tok);
}
rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
candidate_auth_tok);
if (rc) {
printk(KERN_ERR
"Unrecognized candidate auth tok type: [%d]\n",
candidate_auth_tok->token_type);
rc = -EINVAL;
goto out_wipe_list;
}
rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
&matching_auth_tok,
crypt_stat->mount_crypt_stat,
candidate_auth_tok_sig);
if (!rc) {
found_auth_tok = 1;
goto found_matching_auth_tok;
}
}
if (!found_auth_tok) {
ecryptfs_printk(KERN_ERR, "Could not find a usable "
"authentication token\n");
rc = -EIO;
goto out_wipe_list;
}
found_matching_auth_tok:
if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
memcpy(&(candidate_auth_tok->token.private_key),
&(matching_auth_tok->token.private_key),
sizeof(struct ecryptfs_private_key));
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
crypt_stat);
} else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
memcpy(&(candidate_auth_tok->token.password),
&(matching_auth_tok->token.password),
sizeof(struct ecryptfs_password));
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
rc = decrypt_passphrase_encrypted_session_key(
candidate_auth_tok, crypt_stat);
} else {
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
rc = -EINVAL;
}
if (rc) {
struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
ecryptfs_printk(KERN_WARNING, "Error decrypting the "
"session key for authentication token with sig "
"[%.*s]; rc = [%d]. Removing auth tok "
"candidate from the list and searching for "
"the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
candidate_auth_tok_sig, rc);
list_for_each_entry_safe(auth_tok_list_item,
auth_tok_list_item_tmp,
&auth_tok_list, list) {
if (candidate_auth_tok
== &auth_tok_list_item->auth_tok) {
list_del(&auth_tok_list_item->list);
kmem_cache_free(
ecryptfs_auth_tok_list_item_cache,
auth_tok_list_item);
goto find_next_matching_auth_tok;
}
}
BUG();
}
rc = ecryptfs_compute_root_iv(crypt_stat);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error computing "
"the root IV\n");
goto out_wipe_list;
}
rc = ecryptfs_init_crypt_ctx(crypt_stat);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error initializing crypto "
"context for cipher [%s]; rc = [%d]\n",
crypt_stat->cipher, rc);
}
out_wipe_list:
wipe_auth_tok_list(&auth_tok_list);
out:
return rc;
}
static int
pki_encrypt_session_key(struct key *auth_tok_key,
struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_key_record *key_rec)
{
struct ecryptfs_msg_ctx *msg_ctx = NULL;
char *payload = NULL;
size_t payload_len = 0;
struct ecryptfs_message *msg;
int rc;
rc = write_tag_66_packet(auth_tok->token.private_key.signature,
ecryptfs_code_for_cipher_string(
crypt_stat->cipher,
crypt_stat->key_size),
crypt_stat, &payload, &payload_len);
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
goto out;
}
rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error sending message to "
"ecryptfsd: %d\n", rc);
goto out;
}
rc = ecryptfs_wait_for_response(msg_ctx, &msg);
if (rc) {
ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
"from the user space daemon\n");
rc = -EIO;
goto out;
}
rc = parse_tag_67_packet(key_rec, msg);
if (rc)
ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
kfree(msg);
out:
kfree(payload);
return rc;
}
/**
* write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
* @dest: Buffer into which to write the packet
* @remaining_bytes: Maximum number of bytes that can be writtn
* @auth_tok_key: The authentication token key to unlock and put when done with
* @auth_tok
* @auth_tok: The authentication token used for generating the tag 1 packet
* @crypt_stat: The cryptographic context
* @key_rec: The key record struct for the tag 1 packet
* @packet_size: This function will write the number of bytes that end
* up constituting the packet; set to zero on error
*
* Returns zero on success; non-zero on error.
*/
static int
write_tag_1_packet(char *dest, size_t *remaining_bytes,
struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
size_t i;
size_t encrypted_session_key_valid = 0;
size_t packet_size_length;
size_t max_packet_size;
int rc = 0;
(*packet_size) = 0;
ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
ECRYPTFS_SIG_SIZE);
encrypted_session_key_valid = 0;
for (i = 0; i < crypt_stat->key_size; i++)
encrypted_session_key_valid |=
auth_tok->session_key.encrypted_key[i];
if (encrypted_session_key_valid) {
memcpy(key_rec->enc_key,
auth_tok->session_key.encrypted_key,
auth_tok->session_key.encrypted_key_size);
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
goto encrypted_session_key_set;
}
if (auth_tok->session_key.encrypted_key_size == 0)
auth_tok->session_key.encrypted_key_size =
auth_tok->token.private_key.key_size;
rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
key_rec);
if (rc) {
printk(KERN_ERR "Failed to encrypt session key via a key "
"module; rc = [%d]\n", rc);
goto out;
}
if (ecryptfs_verbosity > 0) {
ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
}
encrypted_session_key_set:
/* This format is inspired by OpenPGP; see RFC 2440
* packet tag 1 */
max_packet_size = (1 /* Tag 1 identifier */
+ 3 /* Max Tag 1 packet size */
+ 1 /* Version */
+ ECRYPTFS_SIG_SIZE /* Key identifier */
+ 1 /* Cipher identifier */
+ key_rec->enc_key_size); /* Encrypted key size */
if (max_packet_size > (*remaining_bytes)) {
printk(KERN_ERR "Packet length larger than maximum allowable; "
"need up to [%td] bytes, but there are only [%td] "
"available\n", max_packet_size, (*remaining_bytes));
rc = -EINVAL;
goto out;
}
dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
(max_packet_size - 4),
&packet_size_length);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
"header; cannot generate packet length\n");
goto out;
}
(*packet_size) += packet_size_length;
dest[(*packet_size)++] = 0x03; /* version 3 */
memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
(*packet_size) += ECRYPTFS_SIG_SIZE;
dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
memcpy(&dest[(*packet_size)], key_rec->enc_key,
key_rec->enc_key_size);
(*packet_size) += key_rec->enc_key_size;
out:
if (rc)
(*packet_size) = 0;
else
(*remaining_bytes) -= (*packet_size);
return rc;
}
/**
* write_tag_11_packet
* @dest: Target into which Tag 11 packet is to be written
* @remaining_bytes: Maximum packet length
* @contents: Byte array of contents to copy in
* @contents_length: Number of bytes in contents
* @packet_length: Length of the Tag 11 packet written; zero on error
*
* Returns zero on success; non-zero on error.
*/
static int
write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
size_t contents_length, size_t *packet_length)
{
size_t packet_size_length;
size_t max_packet_size;
int rc = 0;
(*packet_length) = 0;
/* This format is inspired by OpenPGP; see RFC 2440
* packet tag 11 */
max_packet_size = (1 /* Tag 11 identifier */
+ 3 /* Max Tag 11 packet size */
+ 1 /* Binary format specifier */
+ 1 /* Filename length */
+ 8 /* Filename ("_CONSOLE") */
+ 4 /* Modification date */
+ contents_length); /* Literal data */
if (max_packet_size > (*remaining_bytes)) {
printk(KERN_ERR "Packet length larger than maximum allowable; "
"need up to [%td] bytes, but there are only [%td] "
"available\n", max_packet_size, (*remaining_bytes));
rc = -EINVAL;
goto out;
}
dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
(max_packet_size - 4),
&packet_size_length);
if (rc) {
printk(KERN_ERR "Error generating tag 11 packet header; cannot "
"generate packet length. rc = [%d]\n", rc);
goto out;
}
(*packet_length) += packet_size_length;
dest[(*packet_length)++] = 0x62; /* binary data format specifier */
dest[(*packet_length)++] = 8;
memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
(*packet_length) += 8;
memset(&dest[(*packet_length)], 0x00, 4);
(*packet_length) += 4;
memcpy(&dest[(*packet_length)], contents, contents_length);
(*packet_length) += contents_length;
out:
if (rc)
(*packet_length) = 0;
else
(*remaining_bytes) -= (*packet_length);
return rc;
}
/**
* write_tag_3_packet
* @dest: Buffer into which to write the packet
* @remaining_bytes: Maximum number of bytes that can be written
* @auth_tok: Authentication token
* @crypt_stat: The cryptographic context
* @key_rec: encrypted key
* @packet_size: This function will write the number of bytes that end
* up constituting the packet; set to zero on error
*
* Returns zero on success; non-zero on error.
*/
static int
write_tag_3_packet(char *dest, size_t *remaining_bytes,
struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
size_t i;
size_t encrypted_session_key_valid = 0;
char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
struct scatterlist dst_sg[2];
struct scatterlist src_sg[2];
struct mutex *tfm_mutex = NULL;
u8 cipher_code;
size_t packet_size_length;
size_t max_packet_size;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
crypt_stat->mount_crypt_stat;
struct blkcipher_desc desc = {
.tfm = NULL,
.flags = CRYPTO_TFM_REQ_MAY_SLEEP
};
int rc = 0;
(*packet_size) = 0;
ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
ECRYPTFS_SIG_SIZE);
rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
crypt_stat->cipher);
if (unlikely(rc)) {
printk(KERN_ERR "Internal error whilst attempting to get "
"tfm and mutex for cipher name [%s]; rc = [%d]\n",
crypt_stat->cipher, rc);
goto out;
}
if (mount_crypt_stat->global_default_cipher_key_size == 0) {
struct blkcipher_alg *alg = crypto_blkcipher_alg(desc.tfm);
printk(KERN_WARNING "No key size specified at mount; "
"defaulting to [%d]\n", alg->max_keysize);
mount_crypt_stat->global_default_cipher_key_size =
alg->max_keysize;
}
if (crypt_stat->key_size == 0)
crypt_stat->key_size =
mount_crypt_stat->global_default_cipher_key_size;
if (auth_tok->session_key.encrypted_key_size == 0)
auth_tok->session_key.encrypted_key_size =
crypt_stat->key_size;
if (crypt_stat->key_size == 24
&& strcmp("aes", crypt_stat->cipher) == 0) {
memset((crypt_stat->key + 24), 0, 8);
auth_tok->session_key.encrypted_key_size = 32;
} else
auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
key_rec->enc_key_size =
auth_tok->session_key.encrypted_key_size;
encrypted_session_key_valid = 0;
for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
encrypted_session_key_valid |=
auth_tok->session_key.encrypted_key[i];
if (encrypted_session_key_valid) {
ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
"using auth_tok->session_key.encrypted_key, "
"where key_rec->enc_key_size = [%zd]\n",
key_rec->enc_key_size);
memcpy(key_rec->enc_key,
auth_tok->session_key.encrypted_key,
key_rec->enc_key_size);
goto encrypted_session_key_set;
}
if (auth_tok->token.password.flags &
ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
ecryptfs_printk(KERN_DEBUG, "Using previously generated "
"session key encryption key of size [%d]\n",
auth_tok->token.password.
session_key_encryption_key_bytes);
memcpy(session_key_encryption_key,
auth_tok->token.password.session_key_encryption_key,
crypt_stat->key_size);
ecryptfs_printk(KERN_DEBUG,
"Cached session key encryption key:\n");
if (ecryptfs_verbosity > 0)
ecryptfs_dump_hex(session_key_encryption_key, 16);
}
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
ecryptfs_dump_hex(session_key_encryption_key, 16);
}
rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
src_sg, 2);
if (rc < 1 || rc > 2) {
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
"for crypt_stat session key; expected rc = 1; "
"got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
rc, key_rec->enc_key_size);
rc = -ENOMEM;
goto out;
}
rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
dst_sg, 2);
if (rc < 1 || rc > 2) {
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
"for crypt_stat encrypted session key; "
"expected rc = 1; got rc = [%d]. "
"key_rec->enc_key_size = [%zd]\n", rc,
key_rec->enc_key_size);
rc = -ENOMEM;
goto out;
}
mutex_lock(tfm_mutex);
rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
crypt_stat->key_size);
if (rc < 0) {
mutex_unlock(tfm_mutex);
ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
"context; rc = [%d]\n", rc);
goto out;
}
rc = 0;
ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
crypt_stat->key_size);
rc = crypto_blkcipher_encrypt(&desc, dst_sg, src_sg,
(*key_rec).enc_key_size);
mutex_unlock(tfm_mutex);
if (rc) {
printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
goto out;
}
ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
if (ecryptfs_verbosity > 0) {
ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
key_rec->enc_key_size);
ecryptfs_dump_hex(key_rec->enc_key,
key_rec->enc_key_size);
}
encrypted_session_key_set:
/* This format is inspired by OpenPGP; see RFC 2440
* packet tag 3 */
max_packet_size = (1 /* Tag 3 identifier */
+ 3 /* Max Tag 3 packet size */
+ 1 /* Version */
+ 1 /* Cipher code */
+ 1 /* S2K specifier */
+ 1 /* Hash identifier */
+ ECRYPTFS_SALT_SIZE /* Salt */
+ 1 /* Hash iterations */
+ key_rec->enc_key_size); /* Encrypted key size */
if (max_packet_size > (*remaining_bytes)) {
printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
"there are only [%td] available\n", max_packet_size,
(*remaining_bytes));
rc = -EINVAL;
goto out;
}
dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
/* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
* to get the number of octets in the actual Tag 3 packet */
rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
(max_packet_size - 4),
&packet_size_length);
if (rc) {
printk(KERN_ERR "Error generating tag 3 packet header; cannot "
"generate packet length. rc = [%d]\n", rc);
goto out;
}
(*packet_size) += packet_size_length;
dest[(*packet_size)++] = 0x04; /* version 4 */
/* TODO: Break from RFC2440 so that arbitrary ciphers can be
* specified with strings */
cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
crypt_stat->key_size);
if (cipher_code == 0) {
ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
"cipher [%s]\n", crypt_stat->cipher);
rc = -EINVAL;
goto out;
}
dest[(*packet_size)++] = cipher_code;
dest[(*packet_size)++] = 0x03; /* S2K */
dest[(*packet_size)++] = 0x01; /* MD5 (TODO: parameterize) */
memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
ECRYPTFS_SALT_SIZE);
(*packet_size) += ECRYPTFS_SALT_SIZE; /* salt */
dest[(*packet_size)++] = 0x60; /* hash iterations (65536) */
memcpy(&dest[(*packet_size)], key_rec->enc_key,
key_rec->enc_key_size);
(*packet_size) += key_rec->enc_key_size;
out:
if (rc)
(*packet_size) = 0;
else
(*remaining_bytes) -= (*packet_size);
return rc;
}
struct kmem_cache *ecryptfs_key_record_cache;
/**
* ecryptfs_generate_key_packet_set
* @dest_base: Virtual address from which to write the key record set
* @crypt_stat: The cryptographic context from which the
* authentication tokens will be retrieved
* @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
* for the global parameters
* @len: The amount written
* @max: The maximum amount of data allowed to be written
*
* Generates a key packet set and writes it to the virtual address
* passed in.
*
* Returns zero on success; non-zero on error.
*/
int
ecryptfs_generate_key_packet_set(char *dest_base,
struct ecryptfs_crypt_stat *crypt_stat,
struct dentry *ecryptfs_dentry, size_t *len,
size_t max)
{
struct ecryptfs_auth_tok *auth_tok;
struct key *auth_tok_key = NULL;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
&ecryptfs_superblock_to_private(
ecryptfs_dentry->d_sb)->mount_crypt_stat;
size_t written;
struct ecryptfs_key_record *key_rec;
struct ecryptfs_key_sig *key_sig;
int rc = 0;
(*len) = 0;
mutex_lock(&crypt_stat->keysig_list_mutex);
key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
if (!key_rec) {
rc = -ENOMEM;
goto out;
}
list_for_each_entry(key_sig, &crypt_stat->keysig_list,
crypt_stat_list) {
memset(key_rec, 0, sizeof(*key_rec));
rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
&auth_tok,
mount_crypt_stat,
key_sig->keysig);
if (rc) {
printk(KERN_WARNING "Unable to retrieve auth tok with "
"sig = [%s]\n", key_sig->keysig);
rc = process_find_global_auth_tok_for_sig_err(rc);
goto out_free;
}
if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
rc = write_tag_3_packet((dest_base + (*len)),
&max, auth_tok,
crypt_stat, key_rec,
&written);
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error "
"writing tag 3 packet\n");
goto out_free;
}
(*len) += written;
/* Write auth tok signature packet */
rc = write_tag_11_packet((dest_base + (*len)), &max,
key_rec->sig,
ECRYPTFS_SIG_SIZE, &written);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error writing "
"auth tok signature packet\n");
goto out_free;
}
(*len) += written;
} else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
rc = write_tag_1_packet(dest_base + (*len), &max,
auth_tok_key, auth_tok,
crypt_stat, key_rec, &written);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error "
"writing tag 1 packet\n");
goto out_free;
}
(*len) += written;
} else {
up_write(&(auth_tok_key->sem));
key_put(auth_tok_key);
ecryptfs_printk(KERN_WARNING, "Unsupported "
"authentication token type\n");
rc = -EINVAL;
goto out_free;
}
}
if (likely(max > 0)) {
dest_base[(*len)] = 0x00;
} else {
ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
rc = -EIO;
}
out_free:
kmem_cache_free(ecryptfs_key_record_cache, key_rec);
out:
if (rc)
(*len) = 0;
mutex_unlock(&crypt_stat->keysig_list_mutex);
return rc;
}
struct kmem_cache *ecryptfs_key_sig_cache;
int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
struct ecryptfs_key_sig *new_key_sig;
new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
if (!new_key_sig) {
printk(KERN_ERR
"Error allocating from ecryptfs_key_sig_cache\n");
return -ENOMEM;
}
memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
/* Caller must hold keysig_list_mutex */
list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
return 0;
}
struct kmem_cache *ecryptfs_global_auth_tok_cache;
int
ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *sig, u32 global_auth_tok_flags)
{
struct ecryptfs_global_auth_tok *new_auth_tok;
int rc = 0;
new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
GFP_KERNEL);
if (!new_auth_tok) {
rc = -ENOMEM;
printk(KERN_ERR "Error allocating from "
"ecryptfs_global_auth_tok_cache\n");
goto out;
}
memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
new_auth_tok->flags = global_auth_tok_flags;
new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
list_add(&new_auth_tok->mount_crypt_stat_list,
&mount_crypt_stat->global_auth_tok_list);
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
out:
return rc;
}
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