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linux/fs/ecryptfs/keystore.c
Michael Halcrow f66e883eb6 eCryptfs: integrate eCryptfs device handle into the module. 
Update the versioning information.  Make the message types generic.  Add an
outgoing message queue to the daemon struct.  Make the functions to parse
and write the packet lengths available to the rest of the module.  Add
functions to create and destroy the daemon structs.  Clean up some of the
comments and make the code a little more consistent with itself.

[akpm@linux-foundation.org: printk fixes]
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 08:06:07 -07:00

1891 lines
58 KiB
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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/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.
*/
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%.16x]\n", err_code);
rc = -EINVAL;
}
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) = (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;
}
/**
* ecryptfs_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.
*/
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 {
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 = 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 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, 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;
}
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 *netlink_message;
size_t netlink_message_length;
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),
&netlink_message, &netlink_message_length);
if (rc) {
ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
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 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 (unlikely(data[(*packet_size)++] != 0x04)) {
printk(KERN_WARNING "Unknown version number [%d]\n",
data[(*packet_size) - 1]);
rc = -EINVAL;
goto out_free;
}
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);
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 (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;
}
static int
ecryptfs_find_global_auth_tok_for_sig(
struct ecryptfs_global_auth_tok **global_auth_tok,
struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
{
struct ecryptfs_global_auth_tok *walker;
int rc = 0;
(*global_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) == 0) {
(*global_auth_tok) = walker;
goto out;
}
}
rc = -EINVAL;
out:
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
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;
}
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)) {
printk(KERN_ERR "Could not find key with description: [%s]\n",
sig);
process_request_key_err(PTR_ERR(*auth_tok_key));
rc = -EINVAL;
goto out;
}
(*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;
}
/**
* 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 ecryptfs_auth_tok **auth_tok,
struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
crypt_stat->mount_crypt_stat;
struct ecryptfs_global_auth_tok *global_auth_tok;
int rc = 0;
(*auth_tok) = NULL;
if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
mount_crypt_stat, sig)) {
struct key *auth_tok_key;
rc = ecryptfs_keyring_auth_tok_for_sig(&auth_tok_key, auth_tok,
sig);
} else
(*auth_tok) = global_auth_tok->global_auth_tok;
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;
struct scatterlist src_sg;
struct mutex *tfm_mutex;
struct blkcipher_desc desc = {
.flags = CRYPTO_TFM_REQ_MAY_SLEEP
};
int rc = 0;
sg_init_table(&dst_sg, 1);
sg_init_table(&src_sg, 1);
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, 1);
if (rc != 1) {
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, 1);
if (rc != 1) {
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 [%d]:\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;
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';
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;
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)) {
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;
}
ecryptfs_find_auth_tok_for_sig(&matching_auth_tok, crypt_stat,
candidate_auth_tok_sig);
if (matching_auth_tok) {
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));
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));
rc = decrypt_passphrase_encrypted_session_key(
candidate_auth_tok, crypt_stat);
}
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", candidate_auth_tok_sig,
ECRYPTFS_SIG_SIZE_HEX, 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 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
* @remaining_bytes: Maximum number of bytes that can be writtn
* @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 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);
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) {
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;
struct scatterlist src_sg;
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 = [%d]\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, 1);
if (rc != 1) {
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
"for crypt_stat session key; expected rc = 1; "
"got rc = [%d]. key_rec->enc_key_size = [%d]\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, 1);
if (rc != 1) {
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
"for crypt_stat encrypted session key; "
"expected rc = 1; got rc = [%d]. "
"key_rec->enc_key_size = [%d]\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 [%d] 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 [%d]:\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);
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 ecryptfs_global_auth_tok *global_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;
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(&global_auth_tok,
mount_crypt_stat,
key_sig->keysig);
if (rc) {
printk(KERN_ERR "Error attempting to get the global "
"auth_tok; rc = [%d]\n", rc);
goto out_free;
}
if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID) {
printk(KERN_WARNING
"Skipping invalid auth tok with sig = [%s]\n",
global_auth_tok->sig);
continue;
}
auth_tok = global_auth_tok->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_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,
crypt_stat, key_rec, &written);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error "
"writing tag 1 packet\n");
goto out_free;
}
(*len) += written;
} else {
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;
int rc = 0;
new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
if (!new_key_sig) {
rc = -ENOMEM;
printk(KERN_ERR
"Error allocating from ecryptfs_key_sig_cache\n");
goto out;
}
memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
mutex_lock(&crypt_stat->keysig_list_mutex);
list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
mutex_unlock(&crypt_stat->keysig_list_mutex);
out:
return rc;
}
struct kmem_cache *ecryptfs_global_auth_tok_cache;
int
ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
char *sig)
{
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->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);
mount_crypt_stat->num_global_auth_toks++;
mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
out:
return rc;
}
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