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libntfs/source/efs.c

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/**
* efs.c - Limited processing of encrypted files
*
* This module is part of ntfs-3g library
*
* Copyright (c) 2009 Martin Bene
* Copyright (c) 2009-2010 Jean-Pierre Andre
*
* This program/include file is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program/include file is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (in the main directory of the NTFS-3G
* distribution in the file COPYING); if not, write to the Free Software
* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_SETXATTR
#include <sys/xattr.h>
#endif
#ifdef HAVE_SYS_SYSMACROS_H
#include <sys/sysmacros.h>
#endif
#include "types.h"
#include "debug.h"
#include "attrib.h"
#include "inode.h"
#include "dir.h"
#include "efs.h"
#include "index.h"
#include "logging.h"
#include "misc.h"
#include "efs.h"
#ifdef HAVE_SETXATTR /* extended attributes interface required */
static ntfschar logged_utility_stream_name[] = {
const_cpu_to_le16('$'),
const_cpu_to_le16('E'),
const_cpu_to_le16('F'),
const_cpu_to_le16('S'),
const_cpu_to_le16(0)
} ;
/*
* Get the ntfs EFS info into an extended attribute
*/
int ntfs_get_efs_info(ntfs_inode *ni, char *value, size_t size)
{
EFS_ATTR_HEADER *efs_info;
s64 attr_size = 0;
if (ni) {
if (ni->flags & FILE_ATTR_ENCRYPTED) {
efs_info = (EFS_ATTR_HEADER*)ntfs_attr_readall(ni,
AT_LOGGED_UTILITY_STREAM,(ntfschar*)NULL, 0,
&attr_size);
if (efs_info
&& (le32_to_cpu(efs_info->length) == attr_size)) {
if (attr_size <= (s64)size) {
if (value)
memcpy(value,efs_info,attr_size);
else {
errno = EFAULT;
attr_size = 0;
}
} else
if (size) {
errno = ERANGE;
attr_size = 0;
}
free (efs_info);
} else {
if (efs_info) {
free(efs_info);
ntfs_log_error("Bad efs_info for inode %lld\n",
(long long)ni->mft_no);
} else {
ntfs_log_error("Could not get efsinfo"
" for inode %lld\n",
(long long)ni->mft_no);
}
errno = EIO;
attr_size = 0;
}
} else {
errno = ENODATA;
ntfs_log_trace("Inode %lld is not encrypted\n",
(long long)ni->mft_no);
}
}
return (attr_size ? (int)attr_size : -errno);
}
/*
* Fix all encrypted AT_DATA attributes of an inode
*
* The fix may require making an attribute non resident, which
* requires more space in the MFT record, and may cause some
* attribute to be expelled and the full record to be reorganized.
* When this happens, the search for data attributes has to be
* reinitialized.
*
* Returns zero if successful.
* -1 if there is a problem.
*/
static int fixup_loop(ntfs_inode *ni)
{
ntfs_attr_search_ctx *ctx;
ntfs_attr *na;
ATTR_RECORD *a;
BOOL restart;
int cnt;
int maxcnt;
int res = 0;
maxcnt = 0;
do {
restart = FALSE;
ctx = ntfs_attr_get_search_ctx(ni, NULL);
if (!ctx) {
ntfs_log_error("Failed to get ctx for efs\n");
res = -1;
}
cnt = 0;
while (!restart && !res
&& !ntfs_attr_lookup(AT_DATA, NULL, 0,
CASE_SENSITIVE, 0, NULL, 0, ctx)) {
cnt++;
a = ctx->attr;
na = ntfs_attr_open(ctx->ntfs_ino, AT_DATA,
(ntfschar*)((u8*)a + le16_to_cpu(a->name_offset)),
a->name_length);
if (!na) {
ntfs_log_error("can't open DATA Attribute\n");
res = -1;
}
if (na && !(ctx->attr->flags & ATTR_IS_ENCRYPTED)) {
if (!NAttrNonResident(na)
&& ntfs_attr_make_non_resident(na, ctx)) {
/*
* ntfs_attr_make_non_resident fails if there
* is not enough space in the MFT record.
* When this happens, force making non-resident
* so that some other attribute is expelled.
*/
if (ntfs_attr_force_non_resident(na)) {
res = -1;
} else {
/* make sure there is some progress */
if (cnt <= maxcnt) {
errno = EIO;
ntfs_log_error("Multiple failure"
" making non resident\n");
res = -1;
} else {
ntfs_attr_put_search_ctx(ctx);
ctx = (ntfs_attr_search_ctx*)NULL;
restart = TRUE;
maxcnt = cnt;
}
}
}
if (!restart && !res
&& ntfs_efs_fixup_attribute(ctx, na)) {
ntfs_log_error("Error in efs fixup of AT_DATA Attribute\n");
res = -1;
}
}
if (na)
ntfs_attr_close(na);
}
} while (restart && !res);
if (ctx)
ntfs_attr_put_search_ctx(ctx);
return (res);
}
/*
* Set the efs data from an extended attribute
* Warning : the new data is not checked
* Returns 0, or -1 if there is a problem
*/
int ntfs_set_efs_info(ntfs_inode *ni, const char *value, size_t size,
int flags)
{
int res;
int written;
ntfs_attr *na;
const EFS_ATTR_HEADER *info_header;
res = 0;
if (ni && value && size) {
if (ni->flags & (FILE_ATTR_ENCRYPTED | FILE_ATTR_COMPRESSED)) {
if (ni->flags & FILE_ATTR_ENCRYPTED) {
ntfs_log_trace("Inode %lld already encrypted\n",
(long long)ni->mft_no);
errno = EEXIST;
} else {
/*
* Possible problem : if encrypted file was
* restored in a compressed directory, it was
* restored as compressed.
* TODO : decompress first.
*/
ntfs_log_error("Inode %lld cannot be encrypted and compressed\n",
(long long)ni->mft_no);
errno = EIO;
}
return -1;
}
info_header = (const EFS_ATTR_HEADER*)value;
/* make sure we get a likely efsinfo */
if (le32_to_cpu(info_header->length) != size) {
errno = EINVAL;
return (-1);
}
if (!ntfs_attr_exist(ni,AT_LOGGED_UTILITY_STREAM,
(ntfschar*)NULL,0)) {
if (!(flags & XATTR_REPLACE)) {
/*
* no logged_utility_stream attribute : add one,
* apparently, this does not feed the new value in
*/
res = ntfs_attr_add(ni,AT_LOGGED_UTILITY_STREAM,
logged_utility_stream_name,4,
(u8*)NULL,(s64)size);
} else {
errno = ENODATA;
res = -1;
}
} else {
errno = EEXIST;
res = -1;
}
if (!res) {
/*
* open and update the existing efs data
*/
na = ntfs_attr_open(ni, AT_LOGGED_UTILITY_STREAM,
logged_utility_stream_name, 4);
if (na) {
/* resize attribute */
res = ntfs_attr_truncate(na, (s64)size);
/* overwrite value if any */
if (!res && value) {
written = (int)ntfs_attr_pwrite(na,
(s64)0, (s64)size, value);
if (written != (s64)size) {
ntfs_log_error("Failed to "
"update efs data\n");
errno = EIO;
res = -1;
}
}
ntfs_attr_close(na);
} else
res = -1;
}
if (!res) {
/* Don't handle AT_DATA Attribute(s) if inode is a directory */
if (!(ni->mrec->flags & MFT_RECORD_IS_DIRECTORY)) {
/* iterate over AT_DATA attributes */
/* set encrypted flag, truncate attribute to match padding bytes */
if (fixup_loop(ni))
return -1;
}
ni->flags |= FILE_ATTR_ENCRYPTED;
NInoSetDirty(ni);
NInoFileNameSetDirty(ni);
}
} else {
errno = EINVAL;
res = -1;
}
return (res ? -1 : 0);
}
/*
* Fixup raw encrypted AT_DATA Attribute
* read padding length from last two bytes
* truncate attribute, make non-resident,
* set data size to match padding length
* set ATTR_IS_ENCRYPTED flag on attribute
*
* Return 0 if successful
* -1 if failed (errno tells why)
*/
int ntfs_efs_fixup_attribute(ntfs_attr_search_ctx *ctx, ntfs_attr *na)
{
u64 newsize;
u64 oldsize;
le16 appended_bytes;
u16 padding_length;
ntfs_inode *ni;
BOOL close_ctx = FALSE;
if (!na) {
ntfs_log_error("no na specified for efs_fixup_attribute\n");
goto err_out;
}
if (!ctx) {
ctx = ntfs_attr_get_search_ctx(na->ni, NULL);
if (!ctx) {
ntfs_log_error("Failed to get ctx for efs\n");
goto err_out;
}
close_ctx = TRUE;
if (ntfs_attr_lookup(AT_DATA, na->name, na->name_len,
CASE_SENSITIVE, 0, NULL, 0, ctx)) {
ntfs_log_error("attr lookup for AT_DATA attribute failed in efs fixup\n");
goto err_out;
}
} else {
if (!NAttrNonResident(na)) {
ntfs_log_error("Cannot make non resident"
" when a context has been allocated\n");
goto err_out;
}
}
/* no extra bytes are added to void attributes */
oldsize = na->data_size;
if (oldsize) {
/* make sure size is valid for a raw encrypted stream */
if ((oldsize & 511) != 2) {
ntfs_log_error("Bad raw encrypted stream\n");
goto err_out;
}
/* read padding length from last two bytes of attribute */
if (ntfs_attr_pread(na, oldsize - 2, 2, &appended_bytes) != 2) {
ntfs_log_error("Error reading padding length\n");
goto err_out;
}
padding_length = le16_to_cpu(appended_bytes);
if (padding_length > 511 || padding_length > na->data_size-2) {
errno = EINVAL;
ntfs_log_error("invalid padding length %d for data_size %lld\n",
padding_length, (long long)oldsize);
goto err_out;
}
newsize = oldsize - padding_length - 2;
/*
* truncate attribute to possibly free clusters allocated
* for the last two bytes, but do not truncate to new size
* to avoid losing useful data
*/
if (ntfs_attr_truncate(na, oldsize - 2)) {
ntfs_log_error("Error truncating attribute\n");
goto err_out;
}
} else
newsize = 0;
/*
* Encrypted AT_DATA Attributes MUST be non-resident
* This has to be done after the attribute is resized, as
* resizing down to zero may cause the attribute to be made
* resident.
*/
if (!NAttrNonResident(na)
&& ntfs_attr_make_non_resident(na, ctx)) {
if (!close_ctx
|| ntfs_attr_force_non_resident(na)) {
ntfs_log_error("Error making DATA attribute non-resident\n");
goto err_out;
} else {
/*
* must reinitialize context after forcing
* non-resident. We need a context for updating
* the state, and at this point, we are sure
* the context is not used elsewhere.
*/
ntfs_attr_reinit_search_ctx(ctx);
if (ntfs_attr_lookup(AT_DATA, na->name, na->name_len,
CASE_SENSITIVE, 0, NULL, 0, ctx)) {
ntfs_log_error("attr lookup for AT_DATA attribute failed in efs fixup\n");
goto err_out;
}
}
}
ni = na->ni;
if (!na->name_len) {
ni->data_size = newsize;
ni->allocated_size = na->allocated_size;
}
NInoSetDirty(ni);
NInoFileNameSetDirty(ni);
ctx->attr->data_size = cpu_to_le64(newsize);
if (le64_to_cpu(ctx->attr->initialized_size) > newsize)
ctx->attr->initialized_size = ctx->attr->data_size;
ctx->attr->flags |= ATTR_IS_ENCRYPTED;
if (close_ctx)
ntfs_attr_put_search_ctx(ctx);
return (0);
err_out:
if (close_ctx && ctx)
ntfs_attr_put_search_ctx(ctx);
return (-1);
}
#endif /* HAVE_SETXATTR */
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