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alistair23-linux/fs/ecryptfs/keystore.c
Michael Halcrow dddfa461fc [PATCH] eCryptfs: Public key; packet management 
Public key support code.  This reads and writes packets in the header that
contain public key encrypted file keys.  It calls the messaging code in the
previous patch to send and receive encryption and decryption request
packets from the userspace daemon.

[akpm@osdl.org: cleab fix]
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:36 -08:00

1730 lines
53 KiB
C
Raw Blame History

/**
* 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/sched.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/key.h>
#include <linux/random.h>
#include <linux/crypto.h>
#include <linux/scatterlist.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.
*/
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%.16x]\n", err_code);
rc = -EINVAL;
}
return rc;
}
/**
* 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
*/
static int 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) = (unsigned char)data[0];
(*length_size) = 1;
} else if (data[0] < 224) {
/* Two-byte length */
(*size) = (((unsigned char)(data[0]) - 192) * 256);
(*size) += ((unsigned char)(data[1]) + 192);
(*length_size) = 2;
} else if (data[0] == 255) {
/* Five-byte length; we're not supposed to see this */
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;
}
/**
* write_packet_length
* @dest: The byte array target into which to write the
* length. Must have at least 5 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.
*/
static int 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 {
rc = -EINVAL;
ecryptfs_printk(KERN_WARNING,
"Unsupported packet size: [%d]\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 = 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 = 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, u16 *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 = 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 received netlink message 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, size_t 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 = 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 = 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;
goto out;
}
if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_67\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 = 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)) {
ecryptfs_printk(KERN_ERR, "message_len [%d]; max len is [%d]\n",
message_len, (i + key_rec->enc_key_size));
rc = -EIO;
goto out;
}
if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
ecryptfs_printk(KERN_ERR, "Encrypted key_size [%d] larger than "
"the maximum key size [%d]\n",
key_rec->enc_key_size,
ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
rc = -EIO;
goto out;
}
memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
out:
return rc;
}
/**
* decrypt_pki_encrypted_session_key - Decrypt the session key with
* the given auth_tok.
*
* Returns Zero on success; non-zero error otherwise.
*/
static int decrypt_pki_encrypted_session_key(
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat)
{
u16 cipher_code = 0;
struct ecryptfs_msg_ctx *msg_ctx;
struct ecryptfs_message *msg = NULL;
char *netlink_message;
size_t netlink_message_length;
int rc;
rc = write_tag_64_packet(mount_crypt_stat->global_auth_tok_sig,
&(auth_tok->session_key),
&netlink_message, &netlink_message_length);
if (rc) {
ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet");
goto out;
}
rc = ecryptfs_send_message(ecryptfs_transport, netlink_message,
netlink_message_length, &msg_ctx);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error sending netlink message\n");
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:
if (msg)
kfree(msg);
return rc;
}
static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
{
struct list_head *walker;
struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
walker = auth_tok_list_head->next;
while (walker != auth_tok_list_head) {
auth_tok_list_item =
list_entry(walker, struct ecryptfs_auth_tok_list_item,
list);
walker = auth_tok_list_item->list.next;
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);
}
auth_tok_list_head->next = NULL;
}
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.
*
* 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;
/* we check that:
* one byte for the Tag 1 ID flag
* two bytes for the body size
* do not exceed the maximum_packet_size
*/
if (unlikely((*packet_size) + 3 > max_packet_size)) {
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
rc = -EINVAL;
goto out;
}
/* check for Tag 1 identifier - one byte */
if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
ecryptfs_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_alloc(ecryptfs_auth_tok_list_item_cache,
GFP_KERNEL);
if (!auth_tok_list_item) {
ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
memset(auth_tok_list_item, 0,
sizeof(struct ecryptfs_auth_tok_list_item));
(*new_auth_tok) = &auth_tok_list_item->auth_tok;
/* check for body size - one to two bytes
*
* ***** TAG 1 Packet Format *****
* | version number | 1 byte |
* | key ID | 8 bytes |
* | public key algorithm | 1 byte |
* | encrypted session key | arbitrary |
*/
rc = parse_packet_length(&data[(*packet_size)], &body_size,
&length_size);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
"rc = [%d]\n", rc);
goto out_free;
}
if (unlikely(body_size < (0x02 + ECRYPTFS_SIG_SIZE))) {
ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
body_size);
rc = -EINVAL;
goto out_free;
}
(*packet_size) += length_size;
if (unlikely((*packet_size) + body_size > max_packet_size)) {
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
rc = -EINVAL;
goto out_free;
}
/* Version 3 (from RFC2440) - one byte */
if (unlikely(data[(*packet_size)++] != 0x03)) {
ecryptfs_printk(KERN_DEBUG, "Unknown version number "
"[%d]\n", data[(*packet_size) - 1]);
rc = -EINVAL;
goto out_free;
}
/* Read Signature */
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 - (0x02 + ECRYPTFS_SIG_SIZE);
if ((*new_auth_tok)->session_key.encrypted_key_size
> ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
ecryptfs_printk(KERN_ERR, "Tag 1 packet contains key larger "
"than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
rc = -EINVAL;
goto out;
}
ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
(*new_auth_tok)->session_key.encrypted_key_size);
memcpy((*new_auth_tok)->session_key.encrypted_key,
&data[(*packet_size)], (body_size - 0x02 - ECRYPTFS_SIG_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_type = ECRYPTFS_PRIVATE_KEY;
ECRYPTFS_SET_FLAG((*new_auth_tok)->flags, ECRYPTFS_PRIVATE_KEY);
/* TODO: Why are we setting this flag here? Don't we want the
* userspace to decrypt the session key? */
ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
ECRYPTFS_CLEAR_FLAG((*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;
/* we check that:
* one byte for the Tag 3 ID flag
* two bytes for the body size
* do not exceed the maximum_packet_size
*/
if (unlikely((*packet_size) + 3 > max_packet_size)) {
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
rc = -EINVAL;
goto out;
}
/* check for Tag 3 identifyer - one byte */
if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\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) {
ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
rc = -ENOMEM;
goto out;
}
(*new_auth_tok) = &auth_tok_list_item->auth_tok;
/* check for body size - one to two bytes */
rc = parse_packet_length(&data[(*packet_size)], &body_size,
&length_size);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
"rc = [%d]\n", rc);
goto out_free;
}
if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) {
ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
body_size);
rc = -EINVAL;
goto out_free;
}
(*packet_size) += length_size;
/* now we know the length of the remainting Tag 3 packet size:
* 5 fix bytes for: version string, cipher, S2K ID, hash algo,
* number of hash iterations
* ECRYPTFS_SALT_SIZE bytes for salt
* body_size bytes minus the stuff above is the encrypted key size
*/
if (unlikely((*packet_size) + body_size > max_packet_size)) {
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
rc = -EINVAL;
goto out_free;
}
/* There are 5 characters of additional information in the
* packet */
(*new_auth_tok)->session_key.encrypted_key_size =
body_size - (0x05 + ECRYPTFS_SALT_SIZE);
ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
(*new_auth_tok)->session_key.encrypted_key_size);
/* Version 4 (from RFC2440) - one byte */
if (unlikely(data[(*packet_size)++] != 0x04)) {
ecryptfs_printk(KERN_DEBUG, "Unknown version number "
"[%d]\n", data[(*packet_size) - 1]);
rc = -EINVAL;
goto out_free;
}
/* cipher - one byte */
ecryptfs_cipher_code_to_string(crypt_stat->cipher,
(u16)data[(*packet_size)]);
/* 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;
}
ecryptfs_init_crypt_ctx(crypt_stat);
/* S2K identifier 3 (from RFC2440) */
if (unlikely(data[(*packet_size)++] != 0x03)) {
ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently "
"supported\n");
rc = -ENOSYS;
goto out_free;
}
/* TODO: finish the hash mapping */
/* hash algorithm - one byte */
switch (data[(*packet_size)++]) {
case 0x01: /* See RFC2440 for these numbers and their mappings */
/* Choose MD5 */
/* salt - ECRYPTFS_SALT_SIZE bytes */
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 */
/* number of hash iterations - one byte */
(*new_auth_tok)->token.password.hash_iterations =
((u32) 16 + (data[(*packet_size)] & 15))
<< ((data[(*packet_size)] >> 4) + 6);
(*packet_size)++;
/* encrypted session key -
* (body_size-5-ECRYPTFS_SALT_SIZE) bytes */
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;
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. */
ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
ECRYPTFS_CLEAR_FLAG((*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;
/* check that:
* one byte for the Tag 11 ID flag
* two bytes for the Tag 11 length
* do not exceed the maximum_packet_size
*/
if (unlikely((*packet_size) + 3 > max_packet_size)) {
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
rc = -EINVAL;
goto out;
}
/* check for Tag 11 identifyer - one byte */
if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
ecryptfs_printk(KERN_WARNING,
"Invalid tag 11 packet format\n");
rc = -EINVAL;
goto out;
}
/* get Tag 11 content length - one or two bytes */
rc = parse_packet_length(&data[(*packet_size)], &body_size,
&length_size);
if (rc) {
ecryptfs_printk(KERN_WARNING,
"Invalid tag 11 packet format\n");
goto out;
}
(*packet_size) += length_size;
if (body_size < 13) {
ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
body_size);
rc = -EINVAL;
goto out;
}
/* We have 13 bytes of surrounding packet values */
(*tag_11_contents_size) = (body_size - 13);
/* now we know the length of the remainting Tag 11 packet size:
* 14 fix bytes for: special flag one, special flag two,
* 12 skipped bytes
* body_size bytes minus the stuff above is the Tag 11 content
*/
/* FIXME why is the body size one byte smaller than the actual
* size of the body?
* this seems to be an error here as well as in
* write_tag_11_packet() */
if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
rc = -EINVAL;
goto out;
}
/* special flag one - one byte */
if (data[(*packet_size)++] != 0x62) {
ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
rc = -EINVAL;
goto out;
}
/* special flag two - one byte */
if (data[(*packet_size)++] != 0x08) {
ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
rc = -EINVAL;
goto out;
}
/* skip the next 12 bytes */
(*packet_size) += 12; /* We don't care about the filename or
* the timestamp */
/* get the Tag 11 contents - tag_11_contents_size bytes */
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;
}
/**
* decrypt_session_key - Decrypt the session key with the given auth_tok.
*
* Returns Zero on success; non-zero error otherwise.
*/
static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat)
{
struct ecryptfs_password *password_s_ptr;
struct scatterlist src_sg[2], dst_sg[2];
struct mutex *tfm_mutex = NULL;
char *encrypted_session_key;
char *session_key;
struct blkcipher_desc desc = {
.flags = CRYPTO_TFM_REQ_MAY_SLEEP
};
int rc = 0;
password_s_ptr = &auth_tok->token.password;
if (ECRYPTFS_CHECK_FLAG(password_s_ptr->flags,
ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET))
ecryptfs_printk(KERN_DEBUG, "Session key encryption key "
"set; skipping key generation\n");
ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])"
":\n",
password_s_ptr->session_key_encryption_key_bytes);
if (ecryptfs_verbosity > 0)
ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key,
password_s_ptr->
session_key_encryption_key_bytes);
if (!strcmp(crypt_stat->cipher,
crypt_stat->mount_crypt_stat->global_default_cipher_name)
&& crypt_stat->mount_crypt_stat->global_key_tfm) {
desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
} else {
char *full_alg_name;
rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
crypt_stat->cipher,
"ecb");
if (rc)
goto out;
desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0,
CRYPTO_ALG_ASYNC);
kfree(full_alg_name);
if (IS_ERR(desc.tfm)) {
rc = PTR_ERR(desc.tfm);
printk(KERN_ERR "Error allocating crypto context; "
"rc = [%d]\n", rc);
goto out;
}
crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY);
}
if (tfm_mutex)
mutex_lock(tfm_mutex);
rc = crypto_blkcipher_setkey(desc.tfm,
password_s_ptr->session_key_encryption_key,
crypt_stat->key_size);
if (rc < 0) {
printk(KERN_ERR "Error setting key for crypto context\n");
rc = -EINVAL;
goto out_free_tfm;
}
/* TODO: virt_to_scatterlist */
encrypted_session_key = (char *)__get_free_page(GFP_KERNEL);
if (!encrypted_session_key) {
ecryptfs_printk(KERN_ERR, "Out of memory\n");
rc = -ENOMEM;
goto out_free_tfm;
}
session_key = (char *)__get_free_page(GFP_KERNEL);
if (!session_key) {
kfree(encrypted_session_key);
ecryptfs_printk(KERN_ERR, "Out of memory\n");
rc = -ENOMEM;
goto out_free_tfm;
}
memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key,
auth_tok->session_key.encrypted_key_size);
src_sg[0].page = virt_to_page(encrypted_session_key);
src_sg[0].offset = 0;
BUG_ON(auth_tok->session_key.encrypted_key_size > PAGE_CACHE_SIZE);
src_sg[0].length = auth_tok->session_key.encrypted_key_size;
dst_sg[0].page = virt_to_page(session_key);
dst_sg[0].offset = 0;
auth_tok->session_key.decrypted_key_size =
auth_tok->session_key.encrypted_key_size;
dst_sg[0].length = auth_tok->session_key.encrypted_key_size;
rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg,
auth_tok->session_key.encrypted_key_size);
if (rc) {
printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
goto out_free_memory;
}
auth_tok->session_key.decrypted_key_size =
auth_tok->session_key.encrypted_key_size;
memcpy(auth_tok->session_key.decrypted_key, session_key,
auth_tok->session_key.decrypted_key_size);
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);
ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
if (ecryptfs_verbosity > 0)
ecryptfs_dump_hex(crypt_stat->key,
crypt_stat->key_size);
out_free_memory:
memset(encrypted_session_key, 0, PAGE_CACHE_SIZE);
free_page((unsigned long)encrypted_session_key);
memset(session_key, 0, PAGE_CACHE_SIZE);
free_page((unsigned long)session_key);
out_free_tfm:
if (tfm_mutex)
mutex_unlock(tfm_mutex);
else
crypto_free_blkcipher(desc.tfm);
out:
return rc;
}
/**
* ecryptfs_parse_packet_set
* @dest: The header page in memory
* @version: Version of file format, to guide parsing behavior
*
* 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 = 0;
size_t next_packet_is_auth_tok_packet;
char sig[ECRYPTFS_SIG_SIZE_HEX];
struct list_head auth_tok_list;
struct list_head *walker;
struct ecryptfs_auth_tok *chosen_auth_tok = NULL;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
&ecryptfs_superblock_to_private(
ecryptfs_dentry->d_sb)->mount_crypt_stat;
struct ecryptfs_auth_tok *candidate_auth_tok = NULL;
size_t packet_size;
struct ecryptfs_auth_tok *new_auth_tok;
unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
size_t tag_11_contents_size;
size_t tag_11_packet_size;
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 [%d]\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';
ECRYPTFS_SET_FLAG(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;
ECRYPTFS_SET_FLAG(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;
break;
default:
ecryptfs_printk(KERN_DEBUG, "No packet at offset "
"[%d] 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)) {
rc = -EINVAL; /* Do not support non-encrypted files in
* the 0.1 release */
goto out;
}
/* If we have a global auth tok, then we should try to use
* it */
if (mount_crypt_stat->global_auth_tok) {
memcpy(sig, mount_crypt_stat->global_auth_tok_sig,
ECRYPTFS_SIG_SIZE_HEX);
chosen_auth_tok = mount_crypt_stat->global_auth_tok;
} else
BUG(); /* We should always have a global auth tok in
* the 0.1 release */
/* Scan list to see if our chosen_auth_tok works */
list_for_each(walker, &auth_tok_list) {
struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
auth_tok_list_item =
list_entry(walker, struct ecryptfs_auth_tok_list_item,
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);
}
/* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */
if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD
&& !strncmp(candidate_auth_tok->token.password.signature,
sig, ECRYPTFS_SIG_SIZE_HEX)) {
found_auth_tok = 1;
goto leave_list;
/* TODO: Transfer the common salt into the
* crypt_stat salt */
} else if ((candidate_auth_tok->token_type
== ECRYPTFS_PRIVATE_KEY)
&& !strncmp(candidate_auth_tok->token.private_key.signature,
sig, ECRYPTFS_SIG_SIZE_HEX)) {
found_auth_tok = 1;
goto leave_list;
}
}
if (!found_auth_tok) {
ecryptfs_printk(KERN_ERR, "Could not find authentication "
"token on temporary list for sig [%.*s]\n",
ECRYPTFS_SIG_SIZE_HEX, sig);
rc = -EIO;
goto out_wipe_list;
}
leave_list:
rc = -ENOTSUPP;
if ((ECRYPTFS_CHECK_FLAG(candidate_auth_tok->flags,
ECRYPTFS_PRIVATE_KEY))) {
memcpy(&(candidate_auth_tok->token.private_key),
&(chosen_auth_tok->token.private_key),
sizeof(struct ecryptfs_private_key));
rc = decrypt_pki_encrypted_session_key(mount_crypt_stat,
candidate_auth_tok,
crypt_stat);
} else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
memcpy(&(candidate_auth_tok->token.password),
&(chosen_auth_tok->token.password),
sizeof(struct ecryptfs_password));
rc = decrypt_session_key(candidate_auth_tok, crypt_stat);
}
if (rc) {
ecryptfs_printk(KERN_ERR, "Error decrypting the "
"session key; rc = [%d]\n", rc);
goto out_wipe_list;
}
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 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 *netlink_payload;
size_t netlink_payload_length;
struct ecryptfs_message *msg;
int rc;
rc = write_tag_66_packet(auth_tok->token.private_key.signature,
ecryptfs_code_for_cipher_string(crypt_stat),
crypt_stat, &netlink_payload,
&netlink_payload_length);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
goto out;
}
rc = ecryptfs_send_message(ecryptfs_transport, netlink_payload,
netlink_payload_length, &msg_ctx);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error sending netlink message\n");
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:
if (netlink_payload)
kfree(netlink_payload);
return rc;
}
/**
* write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
* @dest: Buffer into which to write the packet
* @max: Maximum number of bytes that can be writtn
* @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 max, struct ecryptfs_auth_tok *auth_tok,
struct ecryptfs_crypt_stat *crypt_stat,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
size_t i;
size_t encrypted_session_key_valid = 0;
size_t key_rec_size;
size_t packet_size_length;
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);
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, crypt_stat, key_rec);
if (rc) {
ecryptfs_printk(KERN_ERR, "Failed to encrypt session key "
"via a pki");
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:
/* Now we have a valid key_rec. Append it to the
* key_rec set. */
key_rec_size = (sizeof(struct ecryptfs_key_record)
- ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
+ (key_rec->enc_key_size));
/* TODO: Include a packet size limit as a parameter to this
* function once we have multi-packet headers (for versions
* later than 0.1 */
if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
ecryptfs_printk(KERN_ERR, "Keyset too large\n");
rc = -EINVAL;
goto out;
}
/* ***** TAG 1 Packet Format *****
* | version number | 1 byte |
* | key ID | 8 bytes |
* | public key algorithm | 1 byte |
* | encrypted session key | arbitrary |
*/
if ((0x02 + ECRYPTFS_SIG_SIZE + key_rec->enc_key_size) >= max) {
ecryptfs_printk(KERN_ERR,
"Authentication token is too large\n");
rc = -EINVAL;
goto out;
}
dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
/* This format is inspired by OpenPGP; see RFC 2440
* packet tag 1 */
rc = write_packet_length(&dest[(*packet_size)],
(0x02 + ECRYPTFS_SIG_SIZE +
key_rec->enc_key_size),
&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;
return rc;
}
/**
* write_tag_11_packet
* @dest: Target into which Tag 11 packet is to be written
* @max: 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, int max, char *contents, size_t contents_length,
size_t *packet_length)
{
size_t packet_size_length;
int rc = 0;
(*packet_length) = 0;
if ((13 + contents_length) > max) {
rc = -EINVAL;
ecryptfs_printk(KERN_ERR, "Packet length larger than "
"maximum allowable\n");
goto out;
}
/* General packet header */
/* Packet tag */
dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
/* Packet length */
rc = write_packet_length(&dest[(*packet_length)],
(13 + contents_length), &packet_size_length);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "
"header; cannot generate packet length\n");
goto out;
}
(*packet_length) += packet_size_length;
/* Tag 11 specific */
/* One-octet field that describes how the data is formatted */
dest[(*packet_length)++] = 0x62; /* binary data */
/* One-octet filename length followed by filename */
dest[(*packet_length)++] = 8;
memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
(*packet_length) += 8;
/* Four-octet number indicating modification date */
memset(&dest[(*packet_length)], 0x00, 4);
(*packet_length) += 4;
/* Remainder is literal data */
memcpy(&dest[(*packet_length)], contents, contents_length);
(*packet_length) += contents_length;
out:
if (rc)
(*packet_length) = 0;
return rc;
}
/**
* write_tag_3_packet
* @dest: Buffer into which to write the packet
* @max: 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 max, 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 dest_sg[2];
struct scatterlist src_sg[2];
struct mutex *tfm_mutex = NULL;
size_t key_rec_size;
size_t packet_size_length;
size_t cipher_code;
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);
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);
goto encrypted_session_key_set;
}
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;
}
key_rec->enc_key_size =
auth_tok->session_key.encrypted_key_size;
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) {
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
"for crypt_stat session key\n");
rc = -ENOMEM;
goto out;
}
rc = virt_to_scatterlist(key_rec->enc_key,
key_rec->enc_key_size, dest_sg, 2);
if (!rc) {
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
"for crypt_stat encrypted session key\n");
rc = -ENOMEM;
goto out;
}
if (!strcmp(crypt_stat->cipher,
crypt_stat->mount_crypt_stat->global_default_cipher_name)
&& crypt_stat->mount_crypt_stat->global_key_tfm) {
desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
} else {
char *full_alg_name;
rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
crypt_stat->cipher,
"ecb");
if (rc)
goto out;
desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0,
CRYPTO_ALG_ASYNC);
kfree(full_alg_name);
if (IS_ERR(desc.tfm)) {
rc = PTR_ERR(desc.tfm);
ecryptfs_printk(KERN_ERR, "Could not initialize crypto "
"context for cipher [%s]; rc = [%d]\n",
crypt_stat->cipher, rc);
goto out;
}
crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY);
}
if (tfm_mutex)
mutex_lock(tfm_mutex);
rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
crypt_stat->key_size);
if (rc < 0) {
if (tfm_mutex)
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 [%d] bytes of the key\n",
crypt_stat->key_size);
rc = crypto_blkcipher_encrypt(&desc, dest_sg, src_sg,
(*key_rec).enc_key_size);
if (rc) {
printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
goto out;
}
if (tfm_mutex)
mutex_unlock(tfm_mutex);
ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
if (ecryptfs_verbosity > 0)
ecryptfs_dump_hex(key_rec->enc_key,
key_rec->enc_key_size);
encrypted_session_key_set:
/* Now we have a valid key_rec. Append it to the
* key_rec set. */
key_rec_size = (sizeof(struct ecryptfs_key_record)
- ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
+ (key_rec->enc_key_size));
/* TODO: Include a packet size limit as a parameter to this
* function once we have multi-packet headers (for versions
* later than 0.1 */
if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
ecryptfs_printk(KERN_ERR, "Keyset too large\n");
rc = -EINVAL;
goto out;
}
/* TODO: Packet size limit */
/* We have 5 bytes of surrounding packet data */
if ((0x05 + ECRYPTFS_SALT_SIZE
+ key_rec->enc_key_size) >= max) {
ecryptfs_printk(KERN_ERR, "Authentication token is too "
"large\n");
rc = -EINVAL;
goto out;
}
/* This format is inspired by OpenPGP; see RFC 2440
* packet tag 3 */
dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
/* ver+cipher+s2k+hash+salt+iter+enc_key */
rc = write_packet_length(&dest[(*packet_size)],
(0x05 + ECRYPTFS_SALT_SIZE
+ key_rec->enc_key_size),
&packet_size_length);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet "
"header; cannot generate packet length\n");
goto out;
}
(*packet_size) += packet_size_length;
dest[(*packet_size)++] = 0x04; /* version 4 */
cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
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 (desc.tfm && !tfm_mutex)
crypto_free_blkcipher(desc.tfm);
if (rc)
(*packet_size) = 0;
return rc;
}
/**
* ecryptfs_generate_key_packet_set
* @dest: 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 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;
int rc = 0;
(*len) = 0;
if (mount_crypt_stat->global_auth_tok) {
auth_tok = mount_crypt_stat->global_auth_tok;
if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
rc = write_tag_3_packet((dest_base + (*len)),
max, auth_tok,
crypt_stat, &key_rec,
&written);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error "
"writing tag 3 packet\n");
goto out;
}
(*len) += written;
/* Write auth tok signature packet */
rc = write_tag_11_packet(
(dest_base + (*len)),
(max - (*len)),
key_rec.sig, ECRYPTFS_SIG_SIZE, &written);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error writing "
"auth tok signature packet\n");
goto out;
}
(*len) += written;
} else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
rc = write_tag_1_packet(dest_base + (*len),
max, auth_tok,
crypt_stat,mount_crypt_stat,
&key_rec, &written);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error "
"writing tag 1 packet\n");
goto out;
}
(*len) += written;
} else {
ecryptfs_printk(KERN_WARNING, "Unsupported "
"authentication token type\n");
rc = -EINVAL;
goto out;
}
} else
BUG();
if (likely((max - (*len)) > 0)) {
dest_base[(*len)] = 0x00;
} else {
ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
rc = -EIO;
}
out:
if (rc)
(*len) = 0;
return rc;
}
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