1062 lines
33 KiB
C
1062 lines
33 KiB
C
/**
|
|
* eCryptfs: Linux filesystem encryption layer
|
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* In-kernel key management code. Includes functions to parse and
|
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* write authentication token-related packets with the underlying
|
|
* file.
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*
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* Copyright (C) 2004-2006 International Business Machines Corp.
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* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
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* Michael C. Thompson <mcthomps@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#include <linux/string.h>
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#include <linux/sched.h>
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#include <linux/syscalls.h>
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#include <linux/pagemap.h>
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#include <linux/key.h>
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#include <linux/random.h>
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#include <linux/crypto.h>
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#include <linux/scatterlist.h>
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#include "ecryptfs_kernel.h"
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|
|
|
/**
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* request_key returned an error instead of a valid key address;
|
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* determine the type of error, make appropriate log entries, and
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* return an error code.
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*/
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int process_request_key_err(long err_code)
|
|
{
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int rc = 0;
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|
|
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switch (err_code) {
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case ENOKEY:
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ecryptfs_printk(KERN_WARNING, "No key\n");
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rc = -ENOENT;
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break;
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case EKEYEXPIRED:
|
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ecryptfs_printk(KERN_WARNING, "Key expired\n");
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rc = -ETIME;
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break;
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case EKEYREVOKED:
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|
ecryptfs_printk(KERN_WARNING, "Key revoked\n");
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rc = -EINVAL;
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break;
|
|
default:
|
|
ecryptfs_printk(KERN_WARNING, "Unknown error code: "
|
|
"[0x%.16x]\n", err_code);
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rc = -EINVAL;
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|
}
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return rc;
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}
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|
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static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
|
|
{
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struct list_head *walker;
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struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
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|
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walker = auth_tok_list_head->next;
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while (walker != auth_tok_list_head) {
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auth_tok_list_item =
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list_entry(walker, struct ecryptfs_auth_tok_list_item,
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list);
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walker = auth_tok_list_item->list.next;
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memset(auth_tok_list_item, 0,
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sizeof(struct ecryptfs_auth_tok_list_item));
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kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
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auth_tok_list_item);
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}
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}
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struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
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|
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/**
|
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* parse_packet_length
|
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* @data: Pointer to memory containing length at offset
|
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* @size: This function writes the decoded size to this memory
|
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* address; zero on error
|
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* @length_size: The number of bytes occupied by the encoded length
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*
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* Returns Zero on success
|
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*/
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static int parse_packet_length(unsigned char *data, size_t *size,
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size_t *length_size)
|
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{
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int rc = 0;
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|
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(*length_size) = 0;
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(*size) = 0;
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if (data[0] < 192) {
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/* One-byte length */
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(*size) = data[0];
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(*length_size) = 1;
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} else if (data[0] < 224) {
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/* Two-byte length */
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(*size) = ((data[0] - 192) * 256);
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(*size) += (data[1] + 192);
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(*length_size) = 2;
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} else if (data[0] == 255) {
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/* Five-byte length; we're not supposed to see this */
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ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
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"supported\n");
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rc = -EINVAL;
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goto out;
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} else {
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ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
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rc = -EINVAL;
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goto out;
|
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}
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out:
|
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return rc;
|
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}
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/**
|
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* write_packet_length
|
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* @dest: The byte array target into which to write the
|
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* length. Must have at least 5 bytes allocated.
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* @size: The length to write.
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* @packet_size_length: The number of bytes used to encode the
|
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* packet length is written to this address.
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*
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* Returns zero on success; non-zero on error.
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*/
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static int write_packet_length(char *dest, size_t size,
|
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size_t *packet_size_length)
|
|
{
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int rc = 0;
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|
|
|
if (size < 192) {
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dest[0] = size;
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(*packet_size_length) = 1;
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} else if (size < 65536) {
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dest[0] = (((size - 192) / 256) + 192);
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dest[1] = ((size - 192) % 256);
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(*packet_size_length) = 2;
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} else {
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rc = -EINVAL;
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ecryptfs_printk(KERN_WARNING,
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"Unsupported packet size: [%d]\n", size);
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}
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return rc;
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}
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/**
|
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* parse_tag_3_packet
|
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* @crypt_stat: The cryptographic context to modify based on packet
|
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* contents.
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* @data: The raw bytes of the packet.
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* @auth_tok_list: eCryptfs parses packets into authentication tokens;
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* a new authentication token will be placed at the end
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* of this list for this packet.
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* @new_auth_tok: Pointer to a pointer to memory that this function
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* allocates; sets the memory address of the pointer to
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* NULL on error. This object is added to the
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* auth_tok_list.
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* @packet_size: This function writes the size of the parsed packet
|
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* into this memory location; zero on error.
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* @max_packet_size: maximum number of bytes to parse
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*
|
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* Returns zero on success; non-zero on error.
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*/
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static int
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parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
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unsigned char *data, struct list_head *auth_tok_list,
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struct ecryptfs_auth_tok **new_auth_tok,
|
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size_t *packet_size, size_t max_packet_size)
|
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{
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int rc = 0;
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size_t body_size;
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struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
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size_t length_size;
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|
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(*packet_size) = 0;
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(*new_auth_tok) = NULL;
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/* we check that:
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* one byte for the Tag 3 ID flag
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* two bytes for the body size
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* do not exceed the maximum_packet_size
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*/
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if (unlikely((*packet_size) + 3 > max_packet_size)) {
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ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
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rc = -EINVAL;
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goto out;
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}
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/* check for Tag 3 identifyer - one byte */
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if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
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ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n",
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ECRYPTFS_TAG_3_PACKET_TYPE);
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rc = -EINVAL;
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goto out;
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}
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/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
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* at end of function upon failure */
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auth_tok_list_item =
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kmem_cache_alloc(ecryptfs_auth_tok_list_item_cache, SLAB_KERNEL);
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if (!auth_tok_list_item) {
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ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
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rc = -ENOMEM;
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goto out;
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}
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memset(auth_tok_list_item, 0,
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sizeof(struct ecryptfs_auth_tok_list_item));
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(*new_auth_tok) = &auth_tok_list_item->auth_tok;
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/* check for body size - one to two bytes */
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rc = parse_packet_length(&data[(*packet_size)], &body_size,
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&length_size);
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if (rc) {
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ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
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"rc = [%d]\n", rc);
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goto out_free;
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}
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if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) {
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ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
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body_size);
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rc = -EINVAL;
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goto out_free;
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}
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(*packet_size) += length_size;
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/* now we know the length of the remainting Tag 3 packet size:
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* 5 fix bytes for: version string, cipher, S2K ID, hash algo,
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* number of hash iterations
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* ECRYPTFS_SALT_SIZE bytes for salt
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* body_size bytes minus the stuff above is the encrypted key size
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*/
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if (unlikely((*packet_size) + body_size > max_packet_size)) {
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ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
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rc = -EINVAL;
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goto out_free;
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}
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/* There are 5 characters of additional information in the
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* packet */
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(*new_auth_tok)->session_key.encrypted_key_size =
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body_size - (0x05 + ECRYPTFS_SALT_SIZE);
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ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
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(*new_auth_tok)->session_key.encrypted_key_size);
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/* Version 4 (from RFC2440) - one byte */
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if (unlikely(data[(*packet_size)++] != 0x04)) {
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ecryptfs_printk(KERN_DEBUG, "Unknown version number "
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"[%d]\n", data[(*packet_size) - 1]);
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rc = -EINVAL;
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goto out_free;
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}
|
|
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/* cipher - one byte */
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ecryptfs_cipher_code_to_string(crypt_stat->cipher,
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(u16)data[(*packet_size)]);
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/* A little extra work to differentiate among the AES key
|
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* sizes; see RFC2440 */
|
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switch(data[(*packet_size)++]) {
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case RFC2440_CIPHER_AES_192:
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crypt_stat->key_size = 24;
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break;
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default:
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crypt_stat->key_size =
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(*new_auth_tok)->session_key.encrypted_key_size;
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}
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ecryptfs_init_crypt_ctx(crypt_stat);
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/* S2K identifier 3 (from RFC2440) */
|
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if (unlikely(data[(*packet_size)++] != 0x03)) {
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ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently "
|
|
"supported\n");
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rc = -ENOSYS;
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goto out_free;
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|
}
|
|
|
|
/* TODO: finish the hash mapping */
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|
/* hash algorithm - one byte */
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switch (data[(*packet_size)++]) {
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case 0x01: /* See RFC2440 for these numbers and their mappings */
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/* Choose MD5 */
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/* salt - ECRYPTFS_SALT_SIZE bytes */
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memcpy((*new_auth_tok)->token.password.salt,
|
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&data[(*packet_size)], ECRYPTFS_SALT_SIZE);
|
|
(*packet_size) += ECRYPTFS_SALT_SIZE;
|
|
|
|
/* This conversion was taken straight from RFC2440 */
|
|
/* number of hash iterations - one byte */
|
|
(*new_auth_tok)->token.password.hash_iterations =
|
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((u32) 16 + (data[(*packet_size)] & 15))
|
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<< ((data[(*packet_size)] >> 4) + 6);
|
|
(*packet_size)++;
|
|
|
|
/* encrypted session key -
|
|
* (body_size-5-ECRYPTFS_SALT_SIZE) bytes */
|
|
memcpy((*new_auth_tok)->session_key.encrypted_key,
|
|
&data[(*packet_size)],
|
|
(*new_auth_tok)->session_key.encrypted_key_size);
|
|
(*packet_size) +=
|
|
(*new_auth_tok)->session_key.encrypted_key_size;
|
|
(*new_auth_tok)->session_key.flags &=
|
|
~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
|
|
(*new_auth_tok)->session_key.flags |=
|
|
ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
|
|
(*new_auth_tok)->token.password.hash_algo = 0x01;
|
|
break;
|
|
default:
|
|
ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
|
|
"[%d]\n", data[(*packet_size) - 1]);
|
|
rc = -ENOSYS;
|
|
goto out_free;
|
|
}
|
|
(*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
|
|
/* TODO: Parametarize; we might actually want userspace to
|
|
* decrypt the session key. */
|
|
ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
|
|
ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
|
|
ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
|
|
ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
|
|
list_add(&auth_tok_list_item->list, auth_tok_list);
|
|
goto out;
|
|
out_free:
|
|
(*new_auth_tok) = NULL;
|
|
memset(auth_tok_list_item, 0,
|
|
sizeof(struct ecryptfs_auth_tok_list_item));
|
|
kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
|
|
auth_tok_list_item);
|
|
out:
|
|
if (rc)
|
|
(*packet_size) = 0;
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* parse_tag_11_packet
|
|
* @data: The raw bytes of the packet
|
|
* @contents: This function writes the data contents of the literal
|
|
* packet into this memory location
|
|
* @max_contents_bytes: The maximum number of bytes that this function
|
|
* is allowed to write into contents
|
|
* @tag_11_contents_size: This function writes the size of the parsed
|
|
* contents into this memory location; zero on
|
|
* error
|
|
* @packet_size: This function writes the size of the parsed packet
|
|
* into this memory location; zero on error
|
|
* @max_packet_size: maximum number of bytes to parse
|
|
*
|
|
* Returns zero on success; non-zero on error.
|
|
*/
|
|
static int
|
|
parse_tag_11_packet(unsigned char *data, unsigned char *contents,
|
|
size_t max_contents_bytes, size_t *tag_11_contents_size,
|
|
size_t *packet_size, size_t max_packet_size)
|
|
{
|
|
int rc = 0;
|
|
size_t body_size;
|
|
size_t length_size;
|
|
|
|
(*packet_size) = 0;
|
|
(*tag_11_contents_size) = 0;
|
|
|
|
/* check that:
|
|
* one byte for the Tag 11 ID flag
|
|
* two bytes for the Tag 11 length
|
|
* do not exceed the maximum_packet_size
|
|
*/
|
|
if (unlikely((*packet_size) + 3 > max_packet_size)) {
|
|
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
/* check for Tag 11 identifyer - one byte */
|
|
if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
|
|
ecryptfs_printk(KERN_WARNING,
|
|
"Invalid tag 11 packet format\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
/* get Tag 11 content length - one or two bytes */
|
|
rc = parse_packet_length(&data[(*packet_size)], &body_size,
|
|
&length_size);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING,
|
|
"Invalid tag 11 packet format\n");
|
|
goto out;
|
|
}
|
|
(*packet_size) += length_size;
|
|
|
|
if (body_size < 13) {
|
|
ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
|
|
body_size);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
/* We have 13 bytes of surrounding packet values */
|
|
(*tag_11_contents_size) = (body_size - 13);
|
|
|
|
/* now we know the length of the remainting Tag 11 packet size:
|
|
* 14 fix bytes for: special flag one, special flag two,
|
|
* 12 skipped bytes
|
|
* body_size bytes minus the stuff above is the Tag 11 content
|
|
*/
|
|
/* FIXME why is the body size one byte smaller than the actual
|
|
* size of the body?
|
|
* this seems to be an error here as well as in
|
|
* write_tag_11_packet() */
|
|
if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
|
|
ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
/* special flag one - one byte */
|
|
if (data[(*packet_size)++] != 0x62) {
|
|
ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
/* special flag two - one byte */
|
|
if (data[(*packet_size)++] != 0x08) {
|
|
ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
/* skip the next 12 bytes */
|
|
(*packet_size) += 12; /* We don't care about the filename or
|
|
* the timestamp */
|
|
|
|
/* get the Tag 11 contents - tag_11_contents_size bytes */
|
|
memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
|
|
(*packet_size) += (*tag_11_contents_size);
|
|
|
|
out:
|
|
if (rc) {
|
|
(*packet_size) = 0;
|
|
(*tag_11_contents_size) = 0;
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* decrypt_session_key - Decrypt the session key with the given auth_tok.
|
|
*
|
|
* Returns Zero on success; non-zero error otherwise.
|
|
*/
|
|
static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
|
|
struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
int rc = 0;
|
|
struct ecryptfs_password *password_s_ptr;
|
|
struct crypto_tfm *tfm = NULL;
|
|
struct scatterlist src_sg[2], dst_sg[2];
|
|
struct mutex *tfm_mutex = NULL;
|
|
/* TODO: Use virt_to_scatterlist for these */
|
|
char *encrypted_session_key;
|
|
char *session_key;
|
|
|
|
password_s_ptr = &auth_tok->token.password;
|
|
if (ECRYPTFS_CHECK_FLAG(password_s_ptr->flags,
|
|
ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET))
|
|
ecryptfs_printk(KERN_DEBUG, "Session key encryption key "
|
|
"set; skipping key generation\n");
|
|
ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])"
|
|
":\n",
|
|
password_s_ptr->session_key_encryption_key_bytes);
|
|
if (ecryptfs_verbosity > 0)
|
|
ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key,
|
|
password_s_ptr->
|
|
session_key_encryption_key_bytes);
|
|
if (!strcmp(crypt_stat->cipher,
|
|
crypt_stat->mount_crypt_stat->global_default_cipher_name)
|
|
&& crypt_stat->mount_crypt_stat->global_key_tfm) {
|
|
tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
|
|
tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
|
|
} else {
|
|
tfm = crypto_alloc_tfm(crypt_stat->cipher,
|
|
CRYPTO_TFM_REQ_WEAK_KEY);
|
|
if (!tfm) {
|
|
printk(KERN_ERR "Error allocating crypto context\n");
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
}
|
|
if (password_s_ptr->session_key_encryption_key_bytes
|
|
< crypto_tfm_alg_min_keysize(tfm)) {
|
|
printk(KERN_WARNING "Session key encryption key is [%d] bytes; "
|
|
"minimum keysize for selected cipher is [%d] bytes.\n",
|
|
password_s_ptr->session_key_encryption_key_bytes,
|
|
crypto_tfm_alg_min_keysize(tfm));
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
if (tfm_mutex)
|
|
mutex_lock(tfm_mutex);
|
|
crypto_cipher_setkey(tfm, password_s_ptr->session_key_encryption_key,
|
|
crypt_stat->key_size);
|
|
/* TODO: virt_to_scatterlist */
|
|
encrypted_session_key = (char *)__get_free_page(GFP_KERNEL);
|
|
if (!encrypted_session_key) {
|
|
ecryptfs_printk(KERN_ERR, "Out of memory\n");
|
|
rc = -ENOMEM;
|
|
goto out_free_tfm;
|
|
}
|
|
session_key = (char *)__get_free_page(GFP_KERNEL);
|
|
if (!session_key) {
|
|
kfree(encrypted_session_key);
|
|
ecryptfs_printk(KERN_ERR, "Out of memory\n");
|
|
rc = -ENOMEM;
|
|
goto out_free_tfm;
|
|
}
|
|
memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key,
|
|
auth_tok->session_key.encrypted_key_size);
|
|
src_sg[0].page = virt_to_page(encrypted_session_key);
|
|
src_sg[0].offset = 0;
|
|
BUG_ON(auth_tok->session_key.encrypted_key_size > PAGE_CACHE_SIZE);
|
|
src_sg[0].length = auth_tok->session_key.encrypted_key_size;
|
|
dst_sg[0].page = virt_to_page(session_key);
|
|
dst_sg[0].offset = 0;
|
|
auth_tok->session_key.decrypted_key_size =
|
|
auth_tok->session_key.encrypted_key_size;
|
|
dst_sg[0].length = auth_tok->session_key.encrypted_key_size;
|
|
/* TODO: Handle error condition */
|
|
crypto_cipher_decrypt(tfm, dst_sg, src_sg,
|
|
auth_tok->session_key.encrypted_key_size);
|
|
auth_tok->session_key.decrypted_key_size =
|
|
auth_tok->session_key.encrypted_key_size;
|
|
memcpy(auth_tok->session_key.decrypted_key, session_key,
|
|
auth_tok->session_key.decrypted_key_size);
|
|
auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
|
|
memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
|
|
auth_tok->session_key.decrypted_key_size);
|
|
ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
|
|
ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
|
|
if (ecryptfs_verbosity > 0)
|
|
ecryptfs_dump_hex(crypt_stat->key,
|
|
crypt_stat->key_size);
|
|
memset(encrypted_session_key, 0, PAGE_CACHE_SIZE);
|
|
free_page((unsigned long)encrypted_session_key);
|
|
memset(session_key, 0, PAGE_CACHE_SIZE);
|
|
free_page((unsigned long)session_key);
|
|
out_free_tfm:
|
|
if (tfm_mutex)
|
|
mutex_unlock(tfm_mutex);
|
|
else
|
|
crypto_free_tfm(tfm);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_parse_packet_set
|
|
* @dest: The header page in memory
|
|
* @version: Version of file format, to guide parsing behavior
|
|
*
|
|
* Get crypt_stat to have the file's session key if the requisite key
|
|
* is available to decrypt the session key.
|
|
*
|
|
* Returns Zero if a valid authentication token was retrieved and
|
|
* processed; negative value for file not encrypted or for error
|
|
* conditions.
|
|
*/
|
|
int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
|
|
unsigned char *src,
|
|
struct dentry *ecryptfs_dentry)
|
|
{
|
|
size_t i = 0;
|
|
int rc = 0;
|
|
size_t found_auth_tok = 0;
|
|
size_t next_packet_is_auth_tok_packet;
|
|
char sig[ECRYPTFS_SIG_SIZE_HEX];
|
|
struct list_head auth_tok_list;
|
|
struct list_head *walker;
|
|
struct ecryptfs_auth_tok *chosen_auth_tok = NULL;
|
|
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
|
|
&ecryptfs_superblock_to_private(
|
|
ecryptfs_dentry->d_sb)->mount_crypt_stat;
|
|
struct ecryptfs_auth_tok *candidate_auth_tok = NULL;
|
|
size_t packet_size;
|
|
struct ecryptfs_auth_tok *new_auth_tok;
|
|
unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
|
|
size_t tag_11_contents_size;
|
|
size_t tag_11_packet_size;
|
|
|
|
INIT_LIST_HEAD(&auth_tok_list);
|
|
/* Parse the header to find as many packets as we can, these will be
|
|
* added the our &auth_tok_list */
|
|
next_packet_is_auth_tok_packet = 1;
|
|
while (next_packet_is_auth_tok_packet) {
|
|
size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
|
|
|
|
switch (src[i]) {
|
|
case ECRYPTFS_TAG_3_PACKET_TYPE:
|
|
rc = parse_tag_3_packet(crypt_stat,
|
|
(unsigned char *)&src[i],
|
|
&auth_tok_list, &new_auth_tok,
|
|
&packet_size, max_packet_size);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error parsing "
|
|
"tag 3 packet\n");
|
|
rc = -EIO;
|
|
goto out_wipe_list;
|
|
}
|
|
i += packet_size;
|
|
rc = parse_tag_11_packet((unsigned char *)&src[i],
|
|
sig_tmp_space,
|
|
ECRYPTFS_SIG_SIZE,
|
|
&tag_11_contents_size,
|
|
&tag_11_packet_size,
|
|
max_packet_size);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "No valid "
|
|
"(ecryptfs-specific) literal "
|
|
"packet containing "
|
|
"authentication token "
|
|
"signature found after "
|
|
"tag 3 packet\n");
|
|
rc = -EIO;
|
|
goto out_wipe_list;
|
|
}
|
|
i += tag_11_packet_size;
|
|
if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
|
|
ecryptfs_printk(KERN_ERR, "Expected "
|
|
"signature of size [%d]; "
|
|
"read size [%d]\n",
|
|
ECRYPTFS_SIG_SIZE,
|
|
tag_11_contents_size);
|
|
rc = -EIO;
|
|
goto out_wipe_list;
|
|
}
|
|
ecryptfs_to_hex(new_auth_tok->token.password.signature,
|
|
sig_tmp_space, tag_11_contents_size);
|
|
new_auth_tok->token.password.signature[
|
|
ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
|
|
ECRYPTFS_SET_FLAG(crypt_stat->flags,
|
|
ECRYPTFS_ENCRYPTED);
|
|
break;
|
|
case ECRYPTFS_TAG_11_PACKET_TYPE:
|
|
ecryptfs_printk(KERN_WARNING, "Invalid packet set "
|
|
"(Tag 11 not allowed by itself)\n");
|
|
rc = -EIO;
|
|
goto out_wipe_list;
|
|
break;
|
|
default:
|
|
ecryptfs_printk(KERN_DEBUG, "No packet at offset "
|
|
"[%d] of the file header; hex value of "
|
|
"character is [0x%.2x]\n", i, src[i]);
|
|
next_packet_is_auth_tok_packet = 0;
|
|
}
|
|
}
|
|
if (list_empty(&auth_tok_list)) {
|
|
rc = -EINVAL; /* Do not support non-encrypted files in
|
|
* the 0.1 release */
|
|
goto out;
|
|
}
|
|
/* If we have a global auth tok, then we should try to use
|
|
* it */
|
|
if (mount_crypt_stat->global_auth_tok) {
|
|
memcpy(sig, mount_crypt_stat->global_auth_tok_sig,
|
|
ECRYPTFS_SIG_SIZE_HEX);
|
|
chosen_auth_tok = mount_crypt_stat->global_auth_tok;
|
|
} else
|
|
BUG(); /* We should always have a global auth tok in
|
|
* the 0.1 release */
|
|
/* Scan list to see if our chosen_auth_tok works */
|
|
list_for_each(walker, &auth_tok_list) {
|
|
struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
|
|
auth_tok_list_item =
|
|
list_entry(walker, struct ecryptfs_auth_tok_list_item,
|
|
list);
|
|
candidate_auth_tok = &auth_tok_list_item->auth_tok;
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG,
|
|
"Considering cadidate auth tok:\n");
|
|
ecryptfs_dump_auth_tok(candidate_auth_tok);
|
|
}
|
|
/* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */
|
|
if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD
|
|
&& !strncmp(candidate_auth_tok->token.password.signature,
|
|
sig, ECRYPTFS_SIG_SIZE_HEX)) {
|
|
found_auth_tok = 1;
|
|
goto leave_list;
|
|
/* TODO: Transfer the common salt into the
|
|
* crypt_stat salt */
|
|
}
|
|
}
|
|
leave_list:
|
|
if (!found_auth_tok) {
|
|
ecryptfs_printk(KERN_ERR, "Could not find authentication "
|
|
"token on temporary list for sig [%.*s]\n",
|
|
ECRYPTFS_SIG_SIZE_HEX, sig);
|
|
rc = -EIO;
|
|
goto out_wipe_list;
|
|
} else {
|
|
memcpy(&(candidate_auth_tok->token.password),
|
|
&(chosen_auth_tok->token.password),
|
|
sizeof(struct ecryptfs_password));
|
|
rc = decrypt_session_key(candidate_auth_tok, crypt_stat);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error decrypting the "
|
|
"session key\n");
|
|
goto out_wipe_list;
|
|
}
|
|
rc = ecryptfs_compute_root_iv(crypt_stat);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error computing "
|
|
"the root IV\n");
|
|
goto out_wipe_list;
|
|
}
|
|
}
|
|
rc = ecryptfs_init_crypt_ctx(crypt_stat);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error initializing crypto "
|
|
"context for cipher [%s]; rc = [%d]\n",
|
|
crypt_stat->cipher, rc);
|
|
}
|
|
out_wipe_list:
|
|
wipe_auth_tok_list(&auth_tok_list);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* write_tag_11_packet
|
|
* @dest: Target into which Tag 11 packet is to be written
|
|
* @max: Maximum packet length
|
|
* @contents: Byte array of contents to copy in
|
|
* @contents_length: Number of bytes in contents
|
|
* @packet_length: Length of the Tag 11 packet written; zero on error
|
|
*
|
|
* Returns zero on success; non-zero on error.
|
|
*/
|
|
static int
|
|
write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length,
|
|
size_t *packet_length)
|
|
{
|
|
int rc = 0;
|
|
size_t packet_size_length;
|
|
|
|
(*packet_length) = 0;
|
|
if ((13 + contents_length) > max) {
|
|
rc = -EINVAL;
|
|
ecryptfs_printk(KERN_ERR, "Packet length larger than "
|
|
"maximum allowable\n");
|
|
goto out;
|
|
}
|
|
/* General packet header */
|
|
/* Packet tag */
|
|
dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
|
|
/* Packet length */
|
|
rc = write_packet_length(&dest[(*packet_length)],
|
|
(13 + contents_length), &packet_size_length);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "
|
|
"header; cannot generate packet length\n");
|
|
goto out;
|
|
}
|
|
(*packet_length) += packet_size_length;
|
|
/* Tag 11 specific */
|
|
/* One-octet field that describes how the data is formatted */
|
|
dest[(*packet_length)++] = 0x62; /* binary data */
|
|
/* One-octet filename length followed by filename */
|
|
dest[(*packet_length)++] = 8;
|
|
memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
|
|
(*packet_length) += 8;
|
|
/* Four-octet number indicating modification date */
|
|
memset(&dest[(*packet_length)], 0x00, 4);
|
|
(*packet_length) += 4;
|
|
/* Remainder is literal data */
|
|
memcpy(&dest[(*packet_length)], contents, contents_length);
|
|
(*packet_length) += contents_length;
|
|
out:
|
|
if (rc)
|
|
(*packet_length) = 0;
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* write_tag_3_packet
|
|
* @dest: Buffer into which to write the packet
|
|
* @max: Maximum number of bytes that can be written
|
|
* @auth_tok: Authentication token
|
|
* @crypt_stat: The cryptographic context
|
|
* @key_rec: encrypted key
|
|
* @packet_size: This function will write the number of bytes that end
|
|
* up constituting the packet; set to zero on error
|
|
*
|
|
* Returns zero on success; non-zero on error.
|
|
*/
|
|
static int
|
|
write_tag_3_packet(char *dest, size_t max, struct ecryptfs_auth_tok *auth_tok,
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct ecryptfs_key_record *key_rec, size_t *packet_size)
|
|
{
|
|
int rc = 0;
|
|
|
|
size_t i;
|
|
size_t signature_is_valid = 0;
|
|
size_t encrypted_session_key_valid = 0;
|
|
char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
|
|
struct scatterlist dest_sg[2];
|
|
struct scatterlist src_sg[2];
|
|
struct crypto_tfm *tfm = NULL;
|
|
struct mutex *tfm_mutex = NULL;
|
|
size_t key_rec_size;
|
|
size_t packet_size_length;
|
|
size_t cipher_code;
|
|
|
|
(*packet_size) = 0;
|
|
/* Check for a valid signature on the auth_tok */
|
|
for (i = 0; i < ECRYPTFS_SIG_SIZE_HEX; i++)
|
|
signature_is_valid |= auth_tok->token.password.signature[i];
|
|
if (!signature_is_valid)
|
|
BUG();
|
|
ecryptfs_from_hex((*key_rec).sig, auth_tok->token.password.signature,
|
|
ECRYPTFS_SIG_SIZE);
|
|
encrypted_session_key_valid = 0;
|
|
for (i = 0; i < crypt_stat->key_size; i++)
|
|
encrypted_session_key_valid |=
|
|
auth_tok->session_key.encrypted_key[i];
|
|
if (encrypted_session_key_valid) {
|
|
memcpy((*key_rec).enc_key,
|
|
auth_tok->session_key.encrypted_key,
|
|
auth_tok->session_key.encrypted_key_size);
|
|
goto encrypted_session_key_set;
|
|
}
|
|
if (auth_tok->session_key.encrypted_key_size == 0)
|
|
auth_tok->session_key.encrypted_key_size =
|
|
crypt_stat->key_size;
|
|
if (crypt_stat->key_size == 24
|
|
&& strcmp("aes", crypt_stat->cipher) == 0) {
|
|
memset((crypt_stat->key + 24), 0, 8);
|
|
auth_tok->session_key.encrypted_key_size = 32;
|
|
}
|
|
(*key_rec).enc_key_size =
|
|
auth_tok->session_key.encrypted_key_size;
|
|
if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags,
|
|
ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) {
|
|
ecryptfs_printk(KERN_DEBUG, "Using previously generated "
|
|
"session key encryption key of size [%d]\n",
|
|
auth_tok->token.password.
|
|
session_key_encryption_key_bytes);
|
|
memcpy(session_key_encryption_key,
|
|
auth_tok->token.password.session_key_encryption_key,
|
|
crypt_stat->key_size);
|
|
ecryptfs_printk(KERN_DEBUG,
|
|
"Cached session key " "encryption key: \n");
|
|
if (ecryptfs_verbosity > 0)
|
|
ecryptfs_dump_hex(session_key_encryption_key, 16);
|
|
}
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
|
|
ecryptfs_dump_hex(session_key_encryption_key, 16);
|
|
}
|
|
rc = virt_to_scatterlist(crypt_stat->key,
|
|
(*key_rec).enc_key_size, src_sg, 2);
|
|
if (!rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
|
|
"for crypt_stat session key\n");
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
rc = virt_to_scatterlist((*key_rec).enc_key,
|
|
(*key_rec).enc_key_size, dest_sg, 2);
|
|
if (!rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
|
|
"for crypt_stat encrypted session key\n");
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
if (!strcmp(crypt_stat->cipher,
|
|
crypt_stat->mount_crypt_stat->global_default_cipher_name)
|
|
&& crypt_stat->mount_crypt_stat->global_key_tfm) {
|
|
tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
|
|
tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
|
|
} else
|
|
tfm = crypto_alloc_tfm(crypt_stat->cipher, 0);
|
|
if (!tfm) {
|
|
ecryptfs_printk(KERN_ERR, "Could not initialize crypto "
|
|
"context for cipher [%s]\n",
|
|
crypt_stat->cipher);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
if (tfm_mutex)
|
|
mutex_lock(tfm_mutex);
|
|
rc = crypto_cipher_setkey(tfm, session_key_encryption_key,
|
|
crypt_stat->key_size);
|
|
if (rc < 0) {
|
|
if (tfm_mutex)
|
|
mutex_unlock(tfm_mutex);
|
|
ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
|
|
"context\n");
|
|
goto out;
|
|
}
|
|
rc = 0;
|
|
ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
|
|
crypt_stat->key_size);
|
|
crypto_cipher_encrypt(tfm, dest_sg, src_sg,
|
|
(*key_rec).enc_key_size);
|
|
if (tfm_mutex)
|
|
mutex_unlock(tfm_mutex);
|
|
ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
|
|
if (ecryptfs_verbosity > 0)
|
|
ecryptfs_dump_hex((*key_rec).enc_key,
|
|
(*key_rec).enc_key_size);
|
|
encrypted_session_key_set:
|
|
/* Now we have a valid key_rec. Append it to the
|
|
* key_rec set. */
|
|
key_rec_size = (sizeof(struct ecryptfs_key_record)
|
|
- ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
|
|
+ ((*key_rec).enc_key_size));
|
|
/* TODO: Include a packet size limit as a parameter to this
|
|
* function once we have multi-packet headers (for versions
|
|
* later than 0.1 */
|
|
if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
|
|
ecryptfs_printk(KERN_ERR, "Keyset too large\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
/* TODO: Packet size limit */
|
|
/* We have 5 bytes of surrounding packet data */
|
|
if ((0x05 + ECRYPTFS_SALT_SIZE
|
|
+ (*key_rec).enc_key_size) >= max) {
|
|
ecryptfs_printk(KERN_ERR, "Authentication token is too "
|
|
"large\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
/* This format is inspired by OpenPGP; see RFC 2440
|
|
* packet tag 3 */
|
|
dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
|
|
/* ver+cipher+s2k+hash+salt+iter+enc_key */
|
|
rc = write_packet_length(&dest[(*packet_size)],
|
|
(0x05 + ECRYPTFS_SALT_SIZE
|
|
+ (*key_rec).enc_key_size),
|
|
&packet_size_length);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet "
|
|
"header; cannot generate packet length\n");
|
|
goto out;
|
|
}
|
|
(*packet_size) += packet_size_length;
|
|
dest[(*packet_size)++] = 0x04; /* version 4 */
|
|
cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
|
|
if (cipher_code == 0) {
|
|
ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
|
|
"cipher [%s]\n", crypt_stat->cipher);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
dest[(*packet_size)++] = cipher_code;
|
|
dest[(*packet_size)++] = 0x03; /* S2K */
|
|
dest[(*packet_size)++] = 0x01; /* MD5 (TODO: parameterize) */
|
|
memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
|
|
ECRYPTFS_SALT_SIZE);
|
|
(*packet_size) += ECRYPTFS_SALT_SIZE; /* salt */
|
|
dest[(*packet_size)++] = 0x60; /* hash iterations (65536) */
|
|
memcpy(&dest[(*packet_size)], (*key_rec).enc_key,
|
|
(*key_rec).enc_key_size);
|
|
(*packet_size) += (*key_rec).enc_key_size;
|
|
out:
|
|
if (tfm && !tfm_mutex)
|
|
crypto_free_tfm(tfm);
|
|
if (rc)
|
|
(*packet_size) = 0;
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_generate_key_packet_set
|
|
* @dest: Virtual address from which to write the key record set
|
|
* @crypt_stat: The cryptographic context from which the
|
|
* authentication tokens will be retrieved
|
|
* @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
|
|
* for the global parameters
|
|
* @len: The amount written
|
|
* @max: The maximum amount of data allowed to be written
|
|
*
|
|
* Generates a key packet set and writes it to the virtual address
|
|
* passed in.
|
|
*
|
|
* Returns zero on success; non-zero on error.
|
|
*/
|
|
int
|
|
ecryptfs_generate_key_packet_set(char *dest_base,
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct dentry *ecryptfs_dentry, size_t *len,
|
|
size_t max)
|
|
{
|
|
int rc = 0;
|
|
struct ecryptfs_auth_tok *auth_tok;
|
|
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
|
|
&ecryptfs_superblock_to_private(
|
|
ecryptfs_dentry->d_sb)->mount_crypt_stat;
|
|
size_t written;
|
|
struct ecryptfs_key_record key_rec;
|
|
|
|
(*len) = 0;
|
|
if (mount_crypt_stat->global_auth_tok) {
|
|
auth_tok = mount_crypt_stat->global_auth_tok;
|
|
if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
|
|
rc = write_tag_3_packet((dest_base + (*len)),
|
|
max, auth_tok,
|
|
crypt_stat, &key_rec,
|
|
&written);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING, "Error "
|
|
"writing tag 3 packet\n");
|
|
goto out;
|
|
}
|
|
(*len) += written;
|
|
/* Write auth tok signature packet */
|
|
rc = write_tag_11_packet(
|
|
(dest_base + (*len)),
|
|
(max - (*len)),
|
|
key_rec.sig, ECRYPTFS_SIG_SIZE, &written);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error writing "
|
|
"auth tok signature packet\n");
|
|
goto out;
|
|
}
|
|
(*len) += written;
|
|
} else {
|
|
ecryptfs_printk(KERN_WARNING, "Unsupported "
|
|
"authentication token type\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING, "Error writing "
|
|
"authentication token packet with sig "
|
|
"= [%s]\n",
|
|
mount_crypt_stat->global_auth_tok_sig);
|
|
rc = -EIO;
|
|
goto out;
|
|
}
|
|
} else
|
|
BUG();
|
|
if (likely((max - (*len)) > 0)) {
|
|
dest_base[(*len)] = 0x00;
|
|
} else {
|
|
ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
|
|
rc = -EIO;
|
|
}
|
|
out:
|
|
if (rc)
|
|
(*len) = 0;
|
|
return rc;
|
|
}
|