/**
 * 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;
    BOOL first;
    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 );
        }
        first = FALSE;
    }
    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 */