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linux/fs/ecryptfs/keystore.c

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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;
}
/**
* 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
*/
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;
}
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)
{
u16 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");
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 = 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 = 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 = 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) {
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:
/* 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 = 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 = 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;
size_t 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 = 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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