1839 lines
54 KiB
C
1839 lines
54 KiB
C
/**
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* eCryptfs: Linux filesystem encryption layer
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*
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* Copyright (C) 1997-2004 Erez Zadok
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* Copyright (C) 2001-2004 Stony Brook University
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* Copyright (C) 2004-2007 International Business Machines Corp.
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* Author(s): Michael A. Halcrow <mahalcro@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/fs.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/random.h>
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#include <linux/compiler.h>
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#include <linux/key.h>
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#include <linux/namei.h>
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#include <linux/crypto.h>
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#include <linux/file.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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static int
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ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
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struct page *dst_page, int dst_offset,
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struct page *src_page, int src_offset, int size,
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unsigned char *iv);
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static int
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ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
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struct page *dst_page, int dst_offset,
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struct page *src_page, int src_offset, int size,
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unsigned char *iv);
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|
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/**
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* ecryptfs_to_hex
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* @dst: Buffer to take hex character representation of contents of
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* src; must be at least of size (src_size * 2)
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* @src: Buffer to be converted to a hex string respresentation
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* @src_size: number of bytes to convert
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*/
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void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
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{
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int x;
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for (x = 0; x < src_size; x++)
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sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
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}
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/**
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* ecryptfs_from_hex
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* @dst: Buffer to take the bytes from src hex; must be at least of
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* size (src_size / 2)
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* @src: Buffer to be converted from a hex string respresentation to raw value
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* @dst_size: size of dst buffer, or number of hex characters pairs to convert
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*/
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void ecryptfs_from_hex(char *dst, char *src, int dst_size)
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{
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int x;
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char tmp[3] = { 0, };
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for (x = 0; x < dst_size; x++) {
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tmp[0] = src[x * 2];
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tmp[1] = src[x * 2 + 1];
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dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
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}
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}
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/**
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* ecryptfs_calculate_md5 - calculates the md5 of @src
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* @dst: Pointer to 16 bytes of allocated memory
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* @crypt_stat: Pointer to crypt_stat struct for the current inode
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* @src: Data to be md5'd
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* @len: Length of @src
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*
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* Uses the allocated crypto context that crypt_stat references to
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* generate the MD5 sum of the contents of src.
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*/
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static int ecryptfs_calculate_md5(char *dst,
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struct ecryptfs_crypt_stat *crypt_stat,
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char *src, int len)
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{
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struct scatterlist sg;
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struct hash_desc desc = {
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.tfm = crypt_stat->hash_tfm,
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.flags = CRYPTO_TFM_REQ_MAY_SLEEP
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};
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int rc = 0;
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mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
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sg_init_one(&sg, (u8 *)src, len);
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if (!desc.tfm) {
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desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
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CRYPTO_ALG_ASYNC);
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if (IS_ERR(desc.tfm)) {
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rc = PTR_ERR(desc.tfm);
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ecryptfs_printk(KERN_ERR, "Error attempting to "
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"allocate crypto context; rc = [%d]\n",
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rc);
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goto out;
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}
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crypt_stat->hash_tfm = desc.tfm;
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}
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crypto_hash_init(&desc);
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crypto_hash_update(&desc, &sg, len);
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crypto_hash_final(&desc, dst);
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mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
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out:
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return rc;
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}
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int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
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char *cipher_name,
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char *chaining_modifier)
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{
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int cipher_name_len = strlen(cipher_name);
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int chaining_modifier_len = strlen(chaining_modifier);
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int algified_name_len;
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int rc;
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algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
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(*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
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if (!(*algified_name)) {
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rc = -ENOMEM;
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goto out;
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}
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snprintf((*algified_name), algified_name_len, "%s(%s)",
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chaining_modifier, cipher_name);
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rc = 0;
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out:
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return rc;
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}
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/**
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* ecryptfs_derive_iv
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* @iv: destination for the derived iv vale
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* @crypt_stat: Pointer to crypt_stat struct for the current inode
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* @offset: Offset of the page whose's iv we are to derive
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*
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* Generate the initialization vector from the given root IV and page
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* offset.
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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 ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
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pgoff_t offset)
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{
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int rc = 0;
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char dst[MD5_DIGEST_SIZE];
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char src[ECRYPTFS_MAX_IV_BYTES + 16];
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if (unlikely(ecryptfs_verbosity > 0)) {
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ecryptfs_printk(KERN_DEBUG, "root iv:\n");
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ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
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}
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/* TODO: It is probably secure to just cast the least
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* significant bits of the root IV into an unsigned long and
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* add the offset to that rather than go through all this
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* hashing business. -Halcrow */
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memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
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memset((src + crypt_stat->iv_bytes), 0, 16);
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snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset);
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if (unlikely(ecryptfs_verbosity > 0)) {
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ecryptfs_printk(KERN_DEBUG, "source:\n");
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ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
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}
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rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
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(crypt_stat->iv_bytes + 16));
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if (rc) {
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ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
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"MD5 while generating IV for a page\n");
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goto out;
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}
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memcpy(iv, dst, crypt_stat->iv_bytes);
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if (unlikely(ecryptfs_verbosity > 0)) {
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ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
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ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
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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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* ecryptfs_init_crypt_stat
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* @crypt_stat: Pointer to the crypt_stat struct to initialize.
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*
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* Initialize the crypt_stat structure.
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*/
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void
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ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
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{
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memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
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mutex_init(&crypt_stat->cs_mutex);
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mutex_init(&crypt_stat->cs_tfm_mutex);
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mutex_init(&crypt_stat->cs_hash_tfm_mutex);
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ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED);
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}
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/**
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* ecryptfs_destruct_crypt_stat
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* @crypt_stat: Pointer to the crypt_stat struct to initialize.
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*
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* Releases all memory associated with a crypt_stat struct.
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*/
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void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
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{
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if (crypt_stat->tfm)
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crypto_free_blkcipher(crypt_stat->tfm);
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if (crypt_stat->hash_tfm)
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crypto_free_hash(crypt_stat->hash_tfm);
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memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
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}
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void ecryptfs_destruct_mount_crypt_stat(
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struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
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{
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if (mount_crypt_stat->global_auth_tok_key)
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key_put(mount_crypt_stat->global_auth_tok_key);
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if (mount_crypt_stat->global_key_tfm)
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crypto_free_blkcipher(mount_crypt_stat->global_key_tfm);
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memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
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}
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/**
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* virt_to_scatterlist
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* @addr: Virtual address
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* @size: Size of data; should be an even multiple of the block size
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* @sg: Pointer to scatterlist array; set to NULL to obtain only
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* the number of scatterlist structs required in array
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* @sg_size: Max array size
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*
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* Fills in a scatterlist array with page references for a passed
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* virtual address.
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*
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* Returns the number of scatterlist structs in array used
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*/
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int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
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int sg_size)
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{
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int i = 0;
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struct page *pg;
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int offset;
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int remainder_of_page;
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while (size > 0 && i < sg_size) {
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pg = virt_to_page(addr);
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offset = offset_in_page(addr);
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if (sg) {
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sg[i].page = pg;
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sg[i].offset = offset;
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}
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remainder_of_page = PAGE_CACHE_SIZE - offset;
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if (size >= remainder_of_page) {
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if (sg)
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sg[i].length = remainder_of_page;
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addr += remainder_of_page;
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size -= remainder_of_page;
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} else {
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if (sg)
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sg[i].length = size;
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addr += size;
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size = 0;
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}
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i++;
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}
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if (size > 0)
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return -ENOMEM;
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return i;
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}
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/**
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* encrypt_scatterlist
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* @crypt_stat: Pointer to the crypt_stat struct to initialize.
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* @dest_sg: Destination of encrypted data
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* @src_sg: Data to be encrypted
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* @size: Length of data to be encrypted
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* @iv: iv to use during encryption
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*
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* Returns the number of bytes encrypted; negative value on error
|
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*/
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static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
|
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struct scatterlist *dest_sg,
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struct scatterlist *src_sg, int size,
|
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unsigned char *iv)
|
|
{
|
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struct blkcipher_desc desc = {
|
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.tfm = crypt_stat->tfm,
|
|
.info = iv,
|
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.flags = CRYPTO_TFM_REQ_MAY_SLEEP
|
|
};
|
|
int rc = 0;
|
|
|
|
BUG_ON(!crypt_stat || !crypt_stat->tfm
|
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|| !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
|
|
ECRYPTFS_STRUCT_INITIALIZED));
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
|
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crypt_stat->key_size);
|
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ecryptfs_dump_hex(crypt_stat->key,
|
|
crypt_stat->key_size);
|
|
}
|
|
/* Consider doing this once, when the file is opened */
|
|
mutex_lock(&crypt_stat->cs_tfm_mutex);
|
|
rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
|
|
crypt_stat->key_size);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
|
|
rc);
|
|
mutex_unlock(&crypt_stat->cs_tfm_mutex);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
|
|
crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
|
|
mutex_unlock(&crypt_stat->cs_tfm_mutex);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static void
|
|
ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
|
|
int *byte_offset,
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
unsigned long extent_num)
|
|
{
|
|
unsigned long lower_extent_num;
|
|
int extents_occupied_by_headers_at_front;
|
|
int bytes_occupied_by_headers_at_front;
|
|
int extent_offset;
|
|
int extents_per_page;
|
|
|
|
bytes_occupied_by_headers_at_front =
|
|
( crypt_stat->header_extent_size
|
|
* crypt_stat->num_header_extents_at_front );
|
|
extents_occupied_by_headers_at_front =
|
|
( bytes_occupied_by_headers_at_front
|
|
/ crypt_stat->extent_size );
|
|
lower_extent_num = extents_occupied_by_headers_at_front + extent_num;
|
|
extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
|
|
(*lower_page_idx) = lower_extent_num / extents_per_page;
|
|
extent_offset = lower_extent_num % extents_per_page;
|
|
(*byte_offset) = extent_offset * crypt_stat->extent_size;
|
|
ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = "
|
|
"[%d]\n", crypt_stat->header_extent_size);
|
|
ecryptfs_printk(KERN_DEBUG, " * crypt_stat->"
|
|
"num_header_extents_at_front = [%d]\n",
|
|
crypt_stat->num_header_extents_at_front);
|
|
ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_"
|
|
"front = [%d]\n", extents_occupied_by_headers_at_front);
|
|
ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n",
|
|
lower_extent_num);
|
|
ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
|
|
extents_per_page);
|
|
ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
|
|
(*lower_page_idx));
|
|
ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
|
|
extent_offset);
|
|
ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
|
|
(*byte_offset));
|
|
}
|
|
|
|
static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx,
|
|
struct page *lower_page,
|
|
struct inode *lower_inode,
|
|
int byte_offset_in_page, int bytes_to_write)
|
|
{
|
|
int rc = 0;
|
|
|
|
if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
|
|
rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
|
|
ctx->param.lower_file,
|
|
byte_offset_in_page,
|
|
bytes_to_write);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error calling lower "
|
|
"commit; rc = [%d]\n", rc);
|
|
goto out;
|
|
}
|
|
} else {
|
|
rc = ecryptfs_writepage_and_release_lower_page(lower_page,
|
|
lower_inode,
|
|
ctx->param.wbc);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error calling lower "
|
|
"writepage(); rc = [%d]\n", rc);
|
|
goto out;
|
|
}
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx,
|
|
struct page **lower_page,
|
|
struct inode *lower_inode,
|
|
unsigned long lower_page_idx,
|
|
int byte_offset_in_page)
|
|
{
|
|
int rc = 0;
|
|
|
|
if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
|
|
/* TODO: Limit this to only the data extents that are
|
|
* needed */
|
|
rc = ecryptfs_get_lower_page(lower_page, lower_inode,
|
|
ctx->param.lower_file,
|
|
lower_page_idx,
|
|
byte_offset_in_page,
|
|
(PAGE_CACHE_SIZE
|
|
- byte_offset_in_page));
|
|
if (rc) {
|
|
ecryptfs_printk(
|
|
KERN_ERR, "Error attempting to grab, map, "
|
|
"and prepare_write lower page with index "
|
|
"[0x%.16x]; rc = [%d]\n", lower_page_idx, rc);
|
|
goto out;
|
|
}
|
|
} else {
|
|
rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL,
|
|
lower_inode,
|
|
lower_page_idx);
|
|
if (rc) {
|
|
ecryptfs_printk(
|
|
KERN_ERR, "Error attempting to grab and map "
|
|
"lower page with index [0x%.16x]; rc = [%d]\n",
|
|
lower_page_idx, rc);
|
|
goto out;
|
|
}
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_encrypt_page
|
|
* @ctx: The context of the page
|
|
*
|
|
* Encrypt an eCryptfs page. This is done on a per-extent basis. Note
|
|
* that eCryptfs pages may straddle the lower pages -- for instance,
|
|
* if the file was created on a machine with an 8K page size
|
|
* (resulting in an 8K header), and then the file is copied onto a
|
|
* host with a 32K page size, then when reading page 0 of the eCryptfs
|
|
* file, 24K of page 0 of the lower file will be read and decrypted,
|
|
* and then 8K of page 1 of the lower file will be read and decrypted.
|
|
*
|
|
* The actual operations performed on each page depends on the
|
|
* contents of the ecryptfs_page_crypt_context struct.
|
|
*
|
|
* Returns zero on success; negative on error
|
|
*/
|
|
int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
|
|
{
|
|
char extent_iv[ECRYPTFS_MAX_IV_BYTES];
|
|
unsigned long base_extent;
|
|
unsigned long extent_offset = 0;
|
|
unsigned long lower_page_idx = 0;
|
|
unsigned long prior_lower_page_idx = 0;
|
|
struct page *lower_page;
|
|
struct inode *lower_inode;
|
|
struct ecryptfs_inode_info *inode_info;
|
|
struct ecryptfs_crypt_stat *crypt_stat;
|
|
int rc = 0;
|
|
int lower_byte_offset = 0;
|
|
int orig_byte_offset = 0;
|
|
int num_extents_per_page;
|
|
#define ECRYPTFS_PAGE_STATE_UNREAD 0
|
|
#define ECRYPTFS_PAGE_STATE_READ 1
|
|
#define ECRYPTFS_PAGE_STATE_MODIFIED 2
|
|
#define ECRYPTFS_PAGE_STATE_WRITTEN 3
|
|
int page_state;
|
|
|
|
lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host);
|
|
inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host);
|
|
crypt_stat = &inode_info->crypt_stat;
|
|
if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
|
|
rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode,
|
|
ctx->param.lower_file);
|
|
if (rc)
|
|
ecryptfs_printk(KERN_ERR, "Error attempting to copy "
|
|
"page at index [0x%.16x]\n",
|
|
ctx->page->index);
|
|
goto out;
|
|
}
|
|
num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
|
|
base_extent = (ctx->page->index * num_extents_per_page);
|
|
page_state = ECRYPTFS_PAGE_STATE_UNREAD;
|
|
while (extent_offset < num_extents_per_page) {
|
|
ecryptfs_extent_to_lwr_pg_idx_and_offset(
|
|
&lower_page_idx, &lower_byte_offset, crypt_stat,
|
|
(base_extent + extent_offset));
|
|
if (prior_lower_page_idx != lower_page_idx
|
|
&& page_state == ECRYPTFS_PAGE_STATE_MODIFIED) {
|
|
rc = ecryptfs_write_out_page(ctx, lower_page,
|
|
lower_inode,
|
|
orig_byte_offset,
|
|
(PAGE_CACHE_SIZE
|
|
- orig_byte_offset));
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error attempting "
|
|
"to write out page; rc = [%d]"
|
|
"\n", rc);
|
|
goto out;
|
|
}
|
|
page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
|
|
}
|
|
if (page_state == ECRYPTFS_PAGE_STATE_UNREAD
|
|
|| page_state == ECRYPTFS_PAGE_STATE_WRITTEN) {
|
|
rc = ecryptfs_read_in_page(ctx, &lower_page,
|
|
lower_inode, lower_page_idx,
|
|
lower_byte_offset);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error attempting "
|
|
"to read in lower page with "
|
|
"index [0x%.16x]; rc = [%d]\n",
|
|
lower_page_idx, rc);
|
|
goto out;
|
|
}
|
|
orig_byte_offset = lower_byte_offset;
|
|
prior_lower_page_idx = lower_page_idx;
|
|
page_state = ECRYPTFS_PAGE_STATE_READ;
|
|
}
|
|
BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED
|
|
|| page_state == ECRYPTFS_PAGE_STATE_READ));
|
|
rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
|
|
(base_extent + extent_offset));
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error attempting to "
|
|
"derive IV for extent [0x%.16x]; "
|
|
"rc = [%d]\n",
|
|
(base_extent + extent_offset), rc);
|
|
goto out;
|
|
}
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
|
|
"with iv:\n");
|
|
ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
|
|
ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
|
|
"encryption:\n");
|
|
ecryptfs_dump_hex((char *)
|
|
(page_address(ctx->page)
|
|
+ (extent_offset
|
|
* crypt_stat->extent_size)), 8);
|
|
}
|
|
rc = ecryptfs_encrypt_page_offset(
|
|
crypt_stat, lower_page, lower_byte_offset, ctx->page,
|
|
(extent_offset * crypt_stat->extent_size),
|
|
crypt_stat->extent_size, extent_iv);
|
|
ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
|
|
"rc = [%d]\n",
|
|
(base_extent + extent_offset), rc);
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
|
|
"encryption:\n");
|
|
ecryptfs_dump_hex((char *)(page_address(lower_page)
|
|
+ lower_byte_offset), 8);
|
|
}
|
|
page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
|
|
extent_offset++;
|
|
}
|
|
BUG_ON(orig_byte_offset != 0);
|
|
rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
|
|
(lower_byte_offset
|
|
+ crypt_stat->extent_size));
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error attempting to write out "
|
|
"page; rc = [%d]\n", rc);
|
|
goto out;
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_decrypt_page
|
|
* @file: The ecryptfs file
|
|
* @page: The page in ecryptfs to decrypt
|
|
*
|
|
* Decrypt an eCryptfs page. This is done on a per-extent basis. Note
|
|
* that eCryptfs pages may straddle the lower pages -- for instance,
|
|
* if the file was created on a machine with an 8K page size
|
|
* (resulting in an 8K header), and then the file is copied onto a
|
|
* host with a 32K page size, then when reading page 0 of the eCryptfs
|
|
* file, 24K of page 0 of the lower file will be read and decrypted,
|
|
* and then 8K of page 1 of the lower file will be read and decrypted.
|
|
*
|
|
* Returns zero on success; negative on error
|
|
*/
|
|
int ecryptfs_decrypt_page(struct file *file, struct page *page)
|
|
{
|
|
char extent_iv[ECRYPTFS_MAX_IV_BYTES];
|
|
unsigned long base_extent;
|
|
unsigned long extent_offset = 0;
|
|
unsigned long lower_page_idx = 0;
|
|
unsigned long prior_lower_page_idx = 0;
|
|
struct page *lower_page;
|
|
char *lower_page_virt = NULL;
|
|
struct inode *lower_inode;
|
|
struct ecryptfs_crypt_stat *crypt_stat;
|
|
int rc = 0;
|
|
int byte_offset;
|
|
int num_extents_per_page;
|
|
int page_state;
|
|
|
|
crypt_stat = &(ecryptfs_inode_to_private(
|
|
page->mapping->host)->crypt_stat);
|
|
lower_inode = ecryptfs_inode_to_lower(page->mapping->host);
|
|
if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
|
|
rc = ecryptfs_do_readpage(file, page, page->index);
|
|
if (rc)
|
|
ecryptfs_printk(KERN_ERR, "Error attempting to copy "
|
|
"page at index [0x%.16x]\n",
|
|
page->index);
|
|
goto out;
|
|
}
|
|
num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
|
|
base_extent = (page->index * num_extents_per_page);
|
|
lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache,
|
|
GFP_KERNEL);
|
|
if (!lower_page_virt) {
|
|
rc = -ENOMEM;
|
|
ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
|
|
"lower page(s)\n");
|
|
goto out;
|
|
}
|
|
lower_page = virt_to_page(lower_page_virt);
|
|
page_state = ECRYPTFS_PAGE_STATE_UNREAD;
|
|
while (extent_offset < num_extents_per_page) {
|
|
ecryptfs_extent_to_lwr_pg_idx_and_offset(
|
|
&lower_page_idx, &byte_offset, crypt_stat,
|
|
(base_extent + extent_offset));
|
|
if (prior_lower_page_idx != lower_page_idx
|
|
|| page_state == ECRYPTFS_PAGE_STATE_UNREAD) {
|
|
rc = ecryptfs_do_readpage(file, lower_page,
|
|
lower_page_idx);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error reading "
|
|
"lower encrypted page; rc = "
|
|
"[%d]\n", rc);
|
|
goto out;
|
|
}
|
|
prior_lower_page_idx = lower_page_idx;
|
|
page_state = ECRYPTFS_PAGE_STATE_READ;
|
|
}
|
|
rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
|
|
(base_extent + extent_offset));
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error attempting to "
|
|
"derive IV for extent [0x%.16x]; rc = "
|
|
"[%d]\n",
|
|
(base_extent + extent_offset), rc);
|
|
goto out;
|
|
}
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
|
|
"with iv:\n");
|
|
ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
|
|
ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
|
|
"decryption:\n");
|
|
ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
|
|
}
|
|
rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
|
|
(extent_offset
|
|
* crypt_stat->extent_size),
|
|
lower_page, byte_offset,
|
|
crypt_stat->extent_size,
|
|
extent_iv);
|
|
if (rc != crypt_stat->extent_size) {
|
|
ecryptfs_printk(KERN_ERR, "Error attempting to "
|
|
"decrypt extent [0x%.16x]\n",
|
|
(base_extent + extent_offset));
|
|
goto out;
|
|
}
|
|
rc = 0;
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
|
|
"decryption:\n");
|
|
ecryptfs_dump_hex((char *)(page_address(page)
|
|
+ byte_offset), 8);
|
|
}
|
|
extent_offset++;
|
|
}
|
|
out:
|
|
if (lower_page_virt)
|
|
kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* decrypt_scatterlist
|
|
*
|
|
* Returns the number of bytes decrypted; negative value on error
|
|
*/
|
|
static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct scatterlist *dest_sg,
|
|
struct scatterlist *src_sg, int size,
|
|
unsigned char *iv)
|
|
{
|
|
struct blkcipher_desc desc = {
|
|
.tfm = crypt_stat->tfm,
|
|
.info = iv,
|
|
.flags = CRYPTO_TFM_REQ_MAY_SLEEP
|
|
};
|
|
int rc = 0;
|
|
|
|
/* Consider doing this once, when the file is opened */
|
|
mutex_lock(&crypt_stat->cs_tfm_mutex);
|
|
rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
|
|
crypt_stat->key_size);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
|
|
rc);
|
|
mutex_unlock(&crypt_stat->cs_tfm_mutex);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
|
|
rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
|
|
mutex_unlock(&crypt_stat->cs_tfm_mutex);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
|
|
rc);
|
|
goto out;
|
|
}
|
|
rc = size;
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_encrypt_page_offset
|
|
*
|
|
* Returns the number of bytes encrypted
|
|
*/
|
|
static int
|
|
ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct page *dst_page, int dst_offset,
|
|
struct page *src_page, int src_offset, int size,
|
|
unsigned char *iv)
|
|
{
|
|
struct scatterlist src_sg, dst_sg;
|
|
|
|
src_sg.page = src_page;
|
|
src_sg.offset = src_offset;
|
|
src_sg.length = size;
|
|
dst_sg.page = dst_page;
|
|
dst_sg.offset = dst_offset;
|
|
dst_sg.length = size;
|
|
return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_decrypt_page_offset
|
|
*
|
|
* Returns the number of bytes decrypted
|
|
*/
|
|
static int
|
|
ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct page *dst_page, int dst_offset,
|
|
struct page *src_page, int src_offset, int size,
|
|
unsigned char *iv)
|
|
{
|
|
struct scatterlist src_sg, dst_sg;
|
|
|
|
src_sg.page = src_page;
|
|
src_sg.offset = src_offset;
|
|
src_sg.length = size;
|
|
dst_sg.page = dst_page;
|
|
dst_sg.offset = dst_offset;
|
|
dst_sg.length = size;
|
|
return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
|
|
}
|
|
|
|
#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
|
|
|
|
/**
|
|
* ecryptfs_init_crypt_ctx
|
|
* @crypt_stat: Uninitilized crypt stats structure
|
|
*
|
|
* Initialize the crypto context.
|
|
*
|
|
* TODO: Performance: Keep a cache of initialized cipher contexts;
|
|
* only init if needed
|
|
*/
|
|
int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
char *full_alg_name;
|
|
int rc = -EINVAL;
|
|
|
|
if (!crypt_stat->cipher) {
|
|
ecryptfs_printk(KERN_ERR, "No cipher specified\n");
|
|
goto out;
|
|
}
|
|
ecryptfs_printk(KERN_DEBUG,
|
|
"Initializing cipher [%s]; strlen = [%d]; "
|
|
"key_size_bits = [%d]\n",
|
|
crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
|
|
crypt_stat->key_size << 3);
|
|
if (crypt_stat->tfm) {
|
|
rc = 0;
|
|
goto out;
|
|
}
|
|
mutex_lock(&crypt_stat->cs_tfm_mutex);
|
|
rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
|
|
crypt_stat->cipher, "cbc");
|
|
if (rc)
|
|
goto out;
|
|
crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
|
|
CRYPTO_ALG_ASYNC);
|
|
kfree(full_alg_name);
|
|
if (IS_ERR(crypt_stat->tfm)) {
|
|
rc = PTR_ERR(crypt_stat->tfm);
|
|
ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
|
|
"Error initializing cipher [%s]\n",
|
|
crypt_stat->cipher);
|
|
mutex_unlock(&crypt_stat->cs_tfm_mutex);
|
|
goto out;
|
|
}
|
|
crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
|
|
mutex_unlock(&crypt_stat->cs_tfm_mutex);
|
|
rc = 0;
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
int extent_size_tmp;
|
|
|
|
crypt_stat->extent_mask = 0xFFFFFFFF;
|
|
crypt_stat->extent_shift = 0;
|
|
if (crypt_stat->extent_size == 0)
|
|
return;
|
|
extent_size_tmp = crypt_stat->extent_size;
|
|
while ((extent_size_tmp & 0x01) == 0) {
|
|
extent_size_tmp >>= 1;
|
|
crypt_stat->extent_mask <<= 1;
|
|
crypt_stat->extent_shift++;
|
|
}
|
|
}
|
|
|
|
void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
/* Default values; may be overwritten as we are parsing the
|
|
* packets. */
|
|
crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
|
|
set_extent_mask_and_shift(crypt_stat);
|
|
crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
|
|
if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
|
|
crypt_stat->header_extent_size =
|
|
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
|
|
} else
|
|
crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
|
|
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
|
|
crypt_stat->num_header_extents_at_front = 0;
|
|
else
|
|
crypt_stat->num_header_extents_at_front = 1;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_compute_root_iv
|
|
* @crypt_stats
|
|
*
|
|
* On error, sets the root IV to all 0's.
|
|
*/
|
|
int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
int rc = 0;
|
|
char dst[MD5_DIGEST_SIZE];
|
|
|
|
BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
|
|
BUG_ON(crypt_stat->iv_bytes <= 0);
|
|
if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) {
|
|
rc = -EINVAL;
|
|
ecryptfs_printk(KERN_WARNING, "Session key not valid; "
|
|
"cannot generate root IV\n");
|
|
goto out;
|
|
}
|
|
rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
|
|
crypt_stat->key_size);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
|
|
"MD5 while generating root IV\n");
|
|
goto out;
|
|
}
|
|
memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
|
|
out:
|
|
if (rc) {
|
|
memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
|
|
ECRYPTFS_SET_FLAG(crypt_stat->flags,
|
|
ECRYPTFS_SECURITY_WARNING);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
get_random_bytes(crypt_stat->key, crypt_stat->key_size);
|
|
ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
|
|
ecryptfs_compute_root_iv(crypt_stat);
|
|
if (unlikely(ecryptfs_verbosity > 0)) {
|
|
ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
|
|
ecryptfs_dump_hex(crypt_stat->key,
|
|
crypt_stat->key_size);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_copy_mount_wide_flags_to_inode_flags
|
|
*
|
|
* This function propagates the mount-wide flags to individual inode
|
|
* flags.
|
|
*/
|
|
static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
|
|
{
|
|
if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
|
|
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
|
|
if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
|
|
crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_set_default_crypt_stat_vals
|
|
* @crypt_stat
|
|
*
|
|
* Default values in the event that policy does not override them.
|
|
*/
|
|
static void ecryptfs_set_default_crypt_stat_vals(
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
|
|
{
|
|
ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
|
|
mount_crypt_stat);
|
|
ecryptfs_set_default_sizes(crypt_stat);
|
|
strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
|
|
crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
|
|
ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
|
|
crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
|
|
crypt_stat->mount_crypt_stat = mount_crypt_stat;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_new_file_context
|
|
* @ecryptfs_dentry
|
|
*
|
|
* If the crypto context for the file has not yet been established,
|
|
* this is where we do that. Establishing a new crypto context
|
|
* involves the following decisions:
|
|
* - What cipher to use?
|
|
* - What set of authentication tokens to use?
|
|
* Here we just worry about getting enough information into the
|
|
* authentication tokens so that we know that they are available.
|
|
* We associate the available authentication tokens with the new file
|
|
* via the set of signatures in the crypt_stat struct. Later, when
|
|
* the headers are actually written out, we may again defer to
|
|
* userspace to perform the encryption of the session key; for the
|
|
* foreseeable future, this will be the case with public key packets.
|
|
*
|
|
* Returns zero on success; non-zero otherwise
|
|
*/
|
|
/* Associate an authentication token(s) with the file */
|
|
int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
|
|
{
|
|
int rc = 0;
|
|
struct ecryptfs_crypt_stat *crypt_stat =
|
|
&ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
|
|
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
|
|
&ecryptfs_superblock_to_private(
|
|
ecryptfs_dentry->d_sb)->mount_crypt_stat;
|
|
int cipher_name_len;
|
|
|
|
ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
|
|
/* See if there are mount crypt options */
|
|
if (mount_crypt_stat->global_auth_tok) {
|
|
ecryptfs_printk(KERN_DEBUG, "Initializing context for new "
|
|
"file using mount_crypt_stat\n");
|
|
ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
|
|
ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
|
|
ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
|
|
mount_crypt_stat);
|
|
memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++],
|
|
mount_crypt_stat->global_auth_tok_sig,
|
|
ECRYPTFS_SIG_SIZE_HEX);
|
|
cipher_name_len =
|
|
strlen(mount_crypt_stat->global_default_cipher_name);
|
|
memcpy(crypt_stat->cipher,
|
|
mount_crypt_stat->global_default_cipher_name,
|
|
cipher_name_len);
|
|
crypt_stat->cipher[cipher_name_len] = '\0';
|
|
crypt_stat->key_size =
|
|
mount_crypt_stat->global_default_cipher_key_size;
|
|
ecryptfs_generate_new_key(crypt_stat);
|
|
} else
|
|
/* We should not encounter this scenario since we
|
|
* should detect lack of global_auth_tok at mount time
|
|
* TODO: Applies to 0.1 release only; remove in future
|
|
* release */
|
|
BUG();
|
|
rc = ecryptfs_init_crypt_ctx(crypt_stat);
|
|
if (rc)
|
|
ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
|
|
"context for cipher [%s]: rc = [%d]\n",
|
|
crypt_stat->cipher, rc);
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* contains_ecryptfs_marker - check for the ecryptfs marker
|
|
* @data: The data block in which to check
|
|
*
|
|
* Returns one if marker found; zero if not found
|
|
*/
|
|
static int contains_ecryptfs_marker(char *data)
|
|
{
|
|
u32 m_1, m_2;
|
|
|
|
memcpy(&m_1, data, 4);
|
|
m_1 = be32_to_cpu(m_1);
|
|
memcpy(&m_2, (data + 4), 4);
|
|
m_2 = be32_to_cpu(m_2);
|
|
if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
|
|
return 1;
|
|
ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
|
|
"MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
|
|
MAGIC_ECRYPTFS_MARKER);
|
|
ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
|
|
"[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
|
|
return 0;
|
|
}
|
|
|
|
struct ecryptfs_flag_map_elem {
|
|
u32 file_flag;
|
|
u32 local_flag;
|
|
};
|
|
|
|
/* Add support for additional flags by adding elements here. */
|
|
static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
|
|
{0x00000001, ECRYPTFS_ENABLE_HMAC},
|
|
{0x00000002, ECRYPTFS_ENCRYPTED},
|
|
{0x00000004, ECRYPTFS_METADATA_IN_XATTR}
|
|
};
|
|
|
|
/**
|
|
* ecryptfs_process_flags
|
|
* @crypt_stat
|
|
* @page_virt: Source data to be parsed
|
|
* @bytes_read: Updated with the number of bytes read
|
|
*
|
|
* Returns zero on success; non-zero if the flag set is invalid
|
|
*/
|
|
static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
|
|
char *page_virt, int *bytes_read)
|
|
{
|
|
int rc = 0;
|
|
int i;
|
|
u32 flags;
|
|
|
|
memcpy(&flags, page_virt, 4);
|
|
flags = be32_to_cpu(flags);
|
|
for (i = 0; i < ((sizeof(ecryptfs_flag_map)
|
|
/ sizeof(struct ecryptfs_flag_map_elem))); i++)
|
|
if (flags & ecryptfs_flag_map[i].file_flag) {
|
|
ECRYPTFS_SET_FLAG(crypt_stat->flags,
|
|
ecryptfs_flag_map[i].local_flag);
|
|
} else
|
|
ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
|
|
ecryptfs_flag_map[i].local_flag);
|
|
/* Version is in top 8 bits of the 32-bit flag vector */
|
|
crypt_stat->file_version = ((flags >> 24) & 0xFF);
|
|
(*bytes_read) = 4;
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* write_ecryptfs_marker
|
|
* @page_virt: The pointer to in a page to begin writing the marker
|
|
* @written: Number of bytes written
|
|
*
|
|
* Marker = 0x3c81b7f5
|
|
*/
|
|
static void write_ecryptfs_marker(char *page_virt, size_t *written)
|
|
{
|
|
u32 m_1, m_2;
|
|
|
|
get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
|
|
m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
|
|
m_1 = cpu_to_be32(m_1);
|
|
memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
|
|
m_2 = cpu_to_be32(m_2);
|
|
memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
|
|
(MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
|
|
(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
|
|
}
|
|
|
|
static void
|
|
write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
|
|
size_t *written)
|
|
{
|
|
u32 flags = 0;
|
|
int i;
|
|
|
|
for (i = 0; i < ((sizeof(ecryptfs_flag_map)
|
|
/ sizeof(struct ecryptfs_flag_map_elem))); i++)
|
|
if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
|
|
ecryptfs_flag_map[i].local_flag))
|
|
flags |= ecryptfs_flag_map[i].file_flag;
|
|
/* Version is in top 8 bits of the 32-bit flag vector */
|
|
flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
|
|
flags = cpu_to_be32(flags);
|
|
memcpy(page_virt, &flags, 4);
|
|
(*written) = 4;
|
|
}
|
|
|
|
struct ecryptfs_cipher_code_str_map_elem {
|
|
char cipher_str[16];
|
|
u16 cipher_code;
|
|
};
|
|
|
|
/* Add support for additional ciphers by adding elements here. The
|
|
* cipher_code is whatever OpenPGP applicatoins use to identify the
|
|
* ciphers. List in order of probability. */
|
|
static struct ecryptfs_cipher_code_str_map_elem
|
|
ecryptfs_cipher_code_str_map[] = {
|
|
{"aes",RFC2440_CIPHER_AES_128 },
|
|
{"blowfish", RFC2440_CIPHER_BLOWFISH},
|
|
{"des3_ede", RFC2440_CIPHER_DES3_EDE},
|
|
{"cast5", RFC2440_CIPHER_CAST_5},
|
|
{"twofish", RFC2440_CIPHER_TWOFISH},
|
|
{"cast6", RFC2440_CIPHER_CAST_6},
|
|
{"aes", RFC2440_CIPHER_AES_192},
|
|
{"aes", RFC2440_CIPHER_AES_256}
|
|
};
|
|
|
|
/**
|
|
* ecryptfs_code_for_cipher_string
|
|
* @str: The string representing the cipher name
|
|
*
|
|
* Returns zero on no match, or the cipher code on match
|
|
*/
|
|
u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
int i;
|
|
u16 code = 0;
|
|
struct ecryptfs_cipher_code_str_map_elem *map =
|
|
ecryptfs_cipher_code_str_map;
|
|
|
|
if (strcmp(crypt_stat->cipher, "aes") == 0) {
|
|
switch (crypt_stat->key_size) {
|
|
case 16:
|
|
code = RFC2440_CIPHER_AES_128;
|
|
break;
|
|
case 24:
|
|
code = RFC2440_CIPHER_AES_192;
|
|
break;
|
|
case 32:
|
|
code = RFC2440_CIPHER_AES_256;
|
|
}
|
|
} else {
|
|
for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
|
|
if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
|
|
code = map[i].cipher_code;
|
|
break;
|
|
}
|
|
}
|
|
return code;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_cipher_code_to_string
|
|
* @str: Destination to write out the cipher name
|
|
* @cipher_code: The code to convert to cipher name string
|
|
*
|
|
* Returns zero on success
|
|
*/
|
|
int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
|
|
{
|
|
int rc = 0;
|
|
int i;
|
|
|
|
str[0] = '\0';
|
|
for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
|
|
if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
|
|
strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
|
|
if (str[0] == '\0') {
|
|
ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
|
|
"[%d]\n", cipher_code);
|
|
rc = -EINVAL;
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_read_header_region
|
|
* @data
|
|
* @dentry
|
|
* @nd
|
|
*
|
|
* Returns zero on success; non-zero otherwise
|
|
*/
|
|
static int ecryptfs_read_header_region(char *data, struct dentry *dentry,
|
|
struct vfsmount *mnt)
|
|
{
|
|
struct file *lower_file;
|
|
mm_segment_t oldfs;
|
|
int rc;
|
|
|
|
if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
|
|
O_RDONLY))) {
|
|
printk(KERN_ERR
|
|
"Error opening lower_file to read header region\n");
|
|
goto out;
|
|
}
|
|
lower_file->f_pos = 0;
|
|
oldfs = get_fs();
|
|
set_fs(get_ds());
|
|
/* For releases 0.1 and 0.2, all of the header information
|
|
* fits in the first data extent-sized region. */
|
|
rc = lower_file->f_op->read(lower_file, (char __user *)data,
|
|
ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
|
|
set_fs(oldfs);
|
|
if ((rc = ecryptfs_close_lower_file(lower_file))) {
|
|
printk(KERN_ERR "Error closing lower_file\n");
|
|
goto out;
|
|
}
|
|
rc = 0;
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry,
|
|
struct vfsmount *mnt)
|
|
{
|
|
int rc;
|
|
|
|
rc = ecryptfs_read_header_region(data, dentry, mnt);
|
|
if (rc)
|
|
goto out;
|
|
if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES))
|
|
rc = -EINVAL;
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
|
|
void
|
|
ecryptfs_write_header_metadata(char *virt,
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
size_t *written)
|
|
{
|
|
u32 header_extent_size;
|
|
u16 num_header_extents_at_front;
|
|
|
|
header_extent_size = (u32)crypt_stat->header_extent_size;
|
|
num_header_extents_at_front =
|
|
(u16)crypt_stat->num_header_extents_at_front;
|
|
header_extent_size = cpu_to_be32(header_extent_size);
|
|
memcpy(virt, &header_extent_size, 4);
|
|
virt += 4;
|
|
num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
|
|
memcpy(virt, &num_header_extents_at_front, 2);
|
|
(*written) = 6;
|
|
}
|
|
|
|
struct kmem_cache *ecryptfs_header_cache_0;
|
|
struct kmem_cache *ecryptfs_header_cache_1;
|
|
struct kmem_cache *ecryptfs_header_cache_2;
|
|
|
|
/**
|
|
* ecryptfs_write_headers_virt
|
|
* @page_virt
|
|
* @crypt_stat
|
|
* @ecryptfs_dentry
|
|
*
|
|
* Format version: 1
|
|
*
|
|
* Header Extent:
|
|
* Octets 0-7: Unencrypted file size (big-endian)
|
|
* Octets 8-15: eCryptfs special marker
|
|
* Octets 16-19: Flags
|
|
* Octet 16: File format version number (between 0 and 255)
|
|
* Octets 17-18: Reserved
|
|
* Octet 19: Bit 1 (lsb): Reserved
|
|
* Bit 2: Encrypted?
|
|
* Bits 3-8: Reserved
|
|
* Octets 20-23: Header extent size (big-endian)
|
|
* Octets 24-25: Number of header extents at front of file
|
|
* (big-endian)
|
|
* Octet 26: Begin RFC 2440 authentication token packet set
|
|
* Data Extent 0:
|
|
* Lower data (CBC encrypted)
|
|
* Data Extent 1:
|
|
* Lower data (CBC encrypted)
|
|
* ...
|
|
*
|
|
* Returns zero on success
|
|
*/
|
|
static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct dentry *ecryptfs_dentry)
|
|
{
|
|
int rc;
|
|
size_t written;
|
|
size_t offset;
|
|
|
|
offset = ECRYPTFS_FILE_SIZE_BYTES;
|
|
write_ecryptfs_marker((page_virt + offset), &written);
|
|
offset += written;
|
|
write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
|
|
offset += written;
|
|
ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
|
|
&written);
|
|
offset += written;
|
|
rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
|
|
ecryptfs_dentry, &written,
|
|
PAGE_CACHE_SIZE - offset);
|
|
if (rc)
|
|
ecryptfs_printk(KERN_WARNING, "Error generating key packet "
|
|
"set; rc = [%d]\n", rc);
|
|
if (size) {
|
|
offset += written;
|
|
*size = offset;
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
static int ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct file *lower_file,
|
|
char *page_virt)
|
|
{
|
|
mm_segment_t oldfs;
|
|
int current_header_page;
|
|
int header_pages;
|
|
ssize_t size;
|
|
int rc = 0;
|
|
|
|
lower_file->f_pos = 0;
|
|
oldfs = get_fs();
|
|
set_fs(get_ds());
|
|
size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE,
|
|
&lower_file->f_pos);
|
|
if (size < 0) {
|
|
rc = (int)size;
|
|
printk(KERN_ERR "Error attempting to write lower page; "
|
|
"rc = [%d]\n", rc);
|
|
set_fs(oldfs);
|
|
goto out;
|
|
}
|
|
header_pages = ((crypt_stat->header_extent_size
|
|
* crypt_stat->num_header_extents_at_front)
|
|
/ PAGE_CACHE_SIZE);
|
|
memset(page_virt, 0, PAGE_CACHE_SIZE);
|
|
current_header_page = 1;
|
|
while (current_header_page < header_pages) {
|
|
size = vfs_write(lower_file, (char __user *)page_virt,
|
|
PAGE_CACHE_SIZE, &lower_file->f_pos);
|
|
if (size < 0) {
|
|
rc = (int)size;
|
|
printk(KERN_ERR "Error attempting to write lower page; "
|
|
"rc = [%d]\n", rc);
|
|
set_fs(oldfs);
|
|
goto out;
|
|
}
|
|
current_header_page++;
|
|
}
|
|
set_fs(oldfs);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
char *page_virt, size_t size)
|
|
{
|
|
int rc;
|
|
|
|
rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
|
|
size, 0);
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_write_metadata
|
|
* @lower_file: The lower file struct, which was returned from dentry_open
|
|
*
|
|
* Write the file headers out. This will likely involve a userspace
|
|
* callout, in which the session key is encrypted with one or more
|
|
* public keys and/or the passphrase necessary to do the encryption is
|
|
* retrieved via a prompt. Exactly what happens at this point should
|
|
* be policy-dependent.
|
|
*
|
|
* Returns zero on success; non-zero on error
|
|
*/
|
|
int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
|
|
struct file *lower_file)
|
|
{
|
|
struct ecryptfs_crypt_stat *crypt_stat;
|
|
char *page_virt;
|
|
size_t size;
|
|
int rc = 0;
|
|
|
|
crypt_stat = &ecryptfs_inode_to_private(
|
|
ecryptfs_dentry->d_inode)->crypt_stat;
|
|
if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
|
|
ECRYPTFS_ENCRYPTED))) {
|
|
if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
|
|
ECRYPTFS_KEY_VALID)) {
|
|
ecryptfs_printk(KERN_DEBUG, "Key is "
|
|
"invalid; bailing out\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
} else {
|
|
rc = -EINVAL;
|
|
ecryptfs_printk(KERN_WARNING,
|
|
"Called with crypt_stat->encrypted == 0\n");
|
|
goto out;
|
|
}
|
|
/* Released in this function */
|
|
page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER);
|
|
if (!page_virt) {
|
|
ecryptfs_printk(KERN_ERR, "Out of memory\n");
|
|
rc = -ENOMEM;
|
|
goto out;
|
|
}
|
|
rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat,
|
|
ecryptfs_dentry);
|
|
if (unlikely(rc)) {
|
|
ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
|
|
memset(page_virt, 0, PAGE_CACHE_SIZE);
|
|
goto out_free;
|
|
}
|
|
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
|
|
rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
|
|
crypt_stat, page_virt,
|
|
size);
|
|
else
|
|
rc = ecryptfs_write_metadata_to_contents(crypt_stat, lower_file,
|
|
page_virt);
|
|
if (rc) {
|
|
printk(KERN_ERR "Error writing metadata out to lower file; "
|
|
"rc = [%d]\n", rc);
|
|
goto out_free;
|
|
}
|
|
out_free:
|
|
kmem_cache_free(ecryptfs_header_cache_0, page_virt);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
|
|
#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
|
|
static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
|
|
char *virt, int *bytes_read,
|
|
int validate_header_size)
|
|
{
|
|
int rc = 0;
|
|
u32 header_extent_size;
|
|
u16 num_header_extents_at_front;
|
|
|
|
memcpy(&header_extent_size, virt, 4);
|
|
header_extent_size = be32_to_cpu(header_extent_size);
|
|
virt += 4;
|
|
memcpy(&num_header_extents_at_front, virt, 2);
|
|
num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
|
|
crypt_stat->header_extent_size = (int)header_extent_size;
|
|
crypt_stat->num_header_extents_at_front =
|
|
(int)num_header_extents_at_front;
|
|
(*bytes_read) = 6;
|
|
if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
|
|
&& ((crypt_stat->header_extent_size
|
|
* crypt_stat->num_header_extents_at_front)
|
|
< ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
|
|
rc = -EINVAL;
|
|
ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
|
|
"[%d]\n", crypt_stat->header_extent_size);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* set_default_header_data
|
|
*
|
|
* For version 0 file format; this function is only for backwards
|
|
* compatibility for files created with the prior versions of
|
|
* eCryptfs.
|
|
*/
|
|
static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
|
|
{
|
|
crypt_stat->header_extent_size = 4096;
|
|
crypt_stat->num_header_extents_at_front = 1;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_read_headers_virt
|
|
*
|
|
* Read/parse the header data. The header format is detailed in the
|
|
* comment block for the ecryptfs_write_headers_virt() function.
|
|
*
|
|
* Returns zero on success
|
|
*/
|
|
static int ecryptfs_read_headers_virt(char *page_virt,
|
|
struct ecryptfs_crypt_stat *crypt_stat,
|
|
struct dentry *ecryptfs_dentry,
|
|
int validate_header_size)
|
|
{
|
|
int rc = 0;
|
|
int offset;
|
|
int bytes_read;
|
|
|
|
ecryptfs_set_default_sizes(crypt_stat);
|
|
crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
|
|
ecryptfs_dentry->d_sb)->mount_crypt_stat;
|
|
offset = ECRYPTFS_FILE_SIZE_BYTES;
|
|
rc = contains_ecryptfs_marker(page_virt + offset);
|
|
if (rc == 0) {
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
|
|
rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
|
|
&bytes_read);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
|
|
goto out;
|
|
}
|
|
if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
|
|
ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
|
|
"file version [%d] is supported by this "
|
|
"version of eCryptfs\n",
|
|
crypt_stat->file_version,
|
|
ECRYPTFS_SUPPORTED_FILE_VERSION);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
offset += bytes_read;
|
|
if (crypt_stat->file_version >= 1) {
|
|
rc = parse_header_metadata(crypt_stat, (page_virt + offset),
|
|
&bytes_read, validate_header_size);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING, "Error reading header "
|
|
"metadata; rc = [%d]\n", rc);
|
|
}
|
|
offset += bytes_read;
|
|
} else
|
|
set_default_header_data(crypt_stat);
|
|
rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
|
|
ecryptfs_dentry);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_read_xattr_region
|
|
*
|
|
* Attempts to read the crypto metadata from the extended attribute
|
|
* region of the lower file.
|
|
*/
|
|
int ecryptfs_read_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry)
|
|
{
|
|
ssize_t size;
|
|
int rc = 0;
|
|
|
|
size = ecryptfs_getxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME,
|
|
page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
|
|
if (size < 0) {
|
|
printk(KERN_DEBUG "Error attempting to read the [%s] "
|
|
"xattr from the lower file; return value = [%zd]\n",
|
|
ECRYPTFS_XATTR_NAME, size);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
int ecryptfs_read_and_validate_xattr_region(char *page_virt,
|
|
struct dentry *ecryptfs_dentry)
|
|
{
|
|
int rc;
|
|
|
|
rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry);
|
|
if (rc)
|
|
goto out;
|
|
if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
|
|
printk(KERN_WARNING "Valid data found in [%s] xattr, but "
|
|
"the marker is invalid\n", ECRYPTFS_XATTR_NAME);
|
|
rc = -EINVAL;
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_read_metadata
|
|
*
|
|
* Common entry point for reading file metadata. From here, we could
|
|
* retrieve the header information from the header region of the file,
|
|
* the xattr region of the file, or some other repostory that is
|
|
* stored separately from the file itself. The current implementation
|
|
* supports retrieving the metadata information from the file contents
|
|
* and from the xattr region.
|
|
*
|
|
* Returns zero if valid headers found and parsed; non-zero otherwise
|
|
*/
|
|
int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry,
|
|
struct file *lower_file)
|
|
{
|
|
int rc = 0;
|
|
char *page_virt = NULL;
|
|
mm_segment_t oldfs;
|
|
ssize_t bytes_read;
|
|
struct ecryptfs_crypt_stat *crypt_stat =
|
|
&ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
|
|
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
|
|
&ecryptfs_superblock_to_private(
|
|
ecryptfs_dentry->d_sb)->mount_crypt_stat;
|
|
|
|
ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
|
|
mount_crypt_stat);
|
|
/* Read the first page from the underlying file */
|
|
page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
|
|
if (!page_virt) {
|
|
rc = -ENOMEM;
|
|
ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
|
|
goto out;
|
|
}
|
|
lower_file->f_pos = 0;
|
|
oldfs = get_fs();
|
|
set_fs(get_ds());
|
|
bytes_read = lower_file->f_op->read(lower_file,
|
|
(char __user *)page_virt,
|
|
ECRYPTFS_DEFAULT_EXTENT_SIZE,
|
|
&lower_file->f_pos);
|
|
set_fs(oldfs);
|
|
if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
|
|
ecryptfs_dentry,
|
|
ECRYPTFS_VALIDATE_HEADER_SIZE);
|
|
if (rc) {
|
|
rc = ecryptfs_read_xattr_region(page_virt,
|
|
ecryptfs_dentry);
|
|
if (rc) {
|
|
printk(KERN_DEBUG "Valid eCryptfs headers not found in "
|
|
"file header region or xattr region\n");
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
|
|
ecryptfs_dentry,
|
|
ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
|
|
if (rc) {
|
|
printk(KERN_DEBUG "Valid eCryptfs headers not found in "
|
|
"file xattr region either\n");
|
|
rc = -EINVAL;
|
|
}
|
|
if (crypt_stat->mount_crypt_stat->flags
|
|
& ECRYPTFS_XATTR_METADATA_ENABLED) {
|
|
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
|
|
} else {
|
|
printk(KERN_WARNING "Attempt to access file with "
|
|
"crypto metadata only in the extended attribute "
|
|
"region, but eCryptfs was mounted without "
|
|
"xattr support enabled. eCryptfs will not treat "
|
|
"this like an encrypted file.\n");
|
|
rc = -EINVAL;
|
|
}
|
|
}
|
|
out:
|
|
if (page_virt) {
|
|
memset(page_virt, 0, PAGE_CACHE_SIZE);
|
|
kmem_cache_free(ecryptfs_header_cache_1, page_virt);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_encode_filename - converts a plaintext file name to cipher text
|
|
* @crypt_stat: The crypt_stat struct associated with the file anem to encode
|
|
* @name: The plaintext name
|
|
* @length: The length of the plaintext
|
|
* @encoded_name: The encypted name
|
|
*
|
|
* Encrypts and encodes a filename into something that constitutes a
|
|
* valid filename for a filesystem, with printable characters.
|
|
*
|
|
* We assume that we have a properly initialized crypto context,
|
|
* pointed to by crypt_stat->tfm.
|
|
*
|
|
* TODO: Implement filename decoding and decryption here, in place of
|
|
* memcpy. We are keeping the framework around for now to (1)
|
|
* facilitate testing of the components needed to implement filename
|
|
* encryption and (2) to provide a code base from which other
|
|
* developers in the community can easily implement this feature.
|
|
*
|
|
* Returns the length of encoded filename; negative if error
|
|
*/
|
|
int
|
|
ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
|
|
const char *name, int length, char **encoded_name)
|
|
{
|
|
int error = 0;
|
|
|
|
(*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
|
|
if (!(*encoded_name)) {
|
|
error = -ENOMEM;
|
|
goto out;
|
|
}
|
|
/* TODO: Filename encryption is a scheduled feature for a
|
|
* future version of eCryptfs. This function is here only for
|
|
* the purpose of providing a framework for other developers
|
|
* to easily implement filename encryption. Hint: Replace this
|
|
* memcpy() with a call to encrypt and encode the
|
|
* filename, the set the length accordingly. */
|
|
memcpy((void *)(*encoded_name), (void *)name, length);
|
|
(*encoded_name)[length] = '\0';
|
|
error = length + 1;
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_decode_filename - converts the cipher text name to plaintext
|
|
* @crypt_stat: The crypt_stat struct associated with the file
|
|
* @name: The filename in cipher text
|
|
* @length: The length of the cipher text name
|
|
* @decrypted_name: The plaintext name
|
|
*
|
|
* Decodes and decrypts the filename.
|
|
*
|
|
* We assume that we have a properly initialized crypto context,
|
|
* pointed to by crypt_stat->tfm.
|
|
*
|
|
* TODO: Implement filename decoding and decryption here, in place of
|
|
* memcpy. We are keeping the framework around for now to (1)
|
|
* facilitate testing of the components needed to implement filename
|
|
* encryption and (2) to provide a code base from which other
|
|
* developers in the community can easily implement this feature.
|
|
*
|
|
* Returns the length of decoded filename; negative if error
|
|
*/
|
|
int
|
|
ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
|
|
const char *name, int length, char **decrypted_name)
|
|
{
|
|
int error = 0;
|
|
|
|
(*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
|
|
if (!(*decrypted_name)) {
|
|
error = -ENOMEM;
|
|
goto out;
|
|
}
|
|
/* TODO: Filename encryption is a scheduled feature for a
|
|
* future version of eCryptfs. This function is here only for
|
|
* the purpose of providing a framework for other developers
|
|
* to easily implement filename encryption. Hint: Replace this
|
|
* memcpy() with a call to decode and decrypt the
|
|
* filename, the set the length accordingly. */
|
|
memcpy((void *)(*decrypted_name), (void *)name, length);
|
|
(*decrypted_name)[length + 1] = '\0'; /* Only for convenience
|
|
* in printing out the
|
|
* string in debug
|
|
* messages */
|
|
error = length;
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* ecryptfs_process_cipher - Perform cipher initialization.
|
|
* @key_tfm: Crypto context for key material, set by this function
|
|
* @cipher_name: Name of the cipher
|
|
* @key_size: Size of the key in bytes
|
|
*
|
|
* Returns zero on success. Any crypto_tfm structs allocated here
|
|
* should be released by other functions, such as on a superblock put
|
|
* event, regardless of whether this function succeeds for fails.
|
|
*/
|
|
int
|
|
ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
|
|
size_t *key_size)
|
|
{
|
|
char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
|
|
char *full_alg_name;
|
|
int rc;
|
|
|
|
*key_tfm = NULL;
|
|
if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
|
|
rc = -EINVAL;
|
|
printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
|
|
"allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
|
|
goto out;
|
|
}
|
|
rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
|
|
"ecb");
|
|
if (rc)
|
|
goto out;
|
|
*key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
|
|
kfree(full_alg_name);
|
|
if (IS_ERR(*key_tfm)) {
|
|
rc = PTR_ERR(*key_tfm);
|
|
printk(KERN_ERR "Unable to allocate crypto cipher with name "
|
|
"[%s]; rc = [%d]\n", cipher_name, rc);
|
|
goto out;
|
|
}
|
|
crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
|
|
if (*key_size == 0) {
|
|
struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
|
|
|
|
*key_size = alg->max_keysize;
|
|
}
|
|
get_random_bytes(dummy_key, *key_size);
|
|
rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
|
|
if (rc) {
|
|
printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
|
|
"cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);
|
|
rc = -EINVAL;
|
|
goto out;
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|