Re: [PATCH] xfs_metadump: obfuscate attrs on CRC fs

From: Eric Sandeen <sandeen@sandeen.net>
To: Eric Sandeen <sandeen@redhat.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs_metadump: obfuscate attrs on CRC fs
Date: Thu, 25 Jun 2015 15:57:28 -0500	[thread overview]
Message-ID: <558C6B38.2070004@sandeen.net> (raw)
In-Reply-To: <557B6222.4030903@redhat.com>

On 6/12/15 5:50 PM, Eric Sandeen wrote:
> Lots of issues in xfs_metadump obfuscation of extended
> attributes with CRC filesystems; this fixes it up.
> 
> The main issues are that the headers differ, and the
> space in the remote blocks differ.
> 
> Tested with a script I'm using to do other metadump
> work; I still owe an xfstest for this and other bits.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Self-NAK on this for now, getting some unexpected weirdness
when I enable warnings in metadump.

-Eric

> ---
> 
> Brief/hacky testcase; populate w/ many attr types with:
> 
> 	MNTPT=/mount/test
> 
>         # FMT_LOCAL
>         touch $MNTPT/S_IFREG.ATTR.FMT_LOCAL
>         setfattr -n user.localattrname -v localattrvalue $MNTPT/S_IFREG.ATTR.FMT_LOCAL
> 
>         # FMT_EXTENTS
>         touch $MNTPT/S_IFREG.ATTR.FMT_EXTENTS
>         for I in `seq 1 50`; do
>                 setfattr -n user.extentattrname$I -v extentattrvalue $MNTPT/S_IFREG.ATTR.FMT_EXTENTS
>         done
> 
>         # FMT_EXTENTS with a single remote 3k value, fill with "C"
>         touch $MNTPT/S_IFREG.ATTR.FMT_EXTENTS_REMOTE3K
>         xfs_io -f -c "pwrite -S 0x43 0 3k" attrvalfile &>/dev/null
>         attr -q -s user.remotebtreeattrname $MNTPT/S_IFREG.ATTR.FMT_EXTENTS_REMOTE3K < attrvalfile
> 
>         # FMT_EXTENTS with a single remote 4k value, fill with "D"
>         touch $MNTPT/S_IFREG.ATTR.FMT_EXTENTS_REMOTE4K
>         xfs_io -f -c "pwrite -S 0x44 0 4k" attrvalfile &>/dev/null
>         attr -q -s user.remotebtreeattrname $MNTPT/S_IFREG.ATTR.FMT_EXTENTS_REMOTE4K < attrvalfile
> 
>         # FMT_BTREE
>         touch $MNTPT/S_IFREG.ATTR.FMT_BTREE
>         for I in `seq 1 1000`; do
>                 setfattr -n user.btreeattrname$I -v btreelongerattrvalue $MNTPT/S_IFREG.ATTR.FMT_BTREE
>         done
> 
> on a crc filesystem, an obfuscated metadump will show all these attrs in the clear
> with getfattr -dR $MNTPT
> 
> diff --git a/db/metadump.c b/db/metadump.c
> index 94f92bc..793f39e 100644
> --- a/db/metadump.c
> +++ b/db/metadump.c
> @@ -1268,39 +1268,54 @@ add_remote_vals(
>  	}
>  }
>  
> +/* Handle remote and leaf attributes */
>  static void
>  obfuscate_attr_block(
> -	char			*block,
> -	xfs_fileoff_t		offset)
> +	char				*block,
> +	xfs_fileoff_t			offset)
>  {
> -	xfs_attr_leafblock_t	*leaf;
> -	int			i;
> -	int			nentries;
> -	xfs_attr_leaf_entry_t 	*entry;
> -	xfs_attr_leaf_name_local_t *local;
> -	xfs_attr_leaf_name_remote_t *remote;
> +	struct xfs_attr_leafblock	*leaf;
> +	struct xfs_attr3_icleaf_hdr	hdr;
> +	int				i;
> +	int				nentries;
> +	xfs_attr_leaf_entry_t 		*entry;
> +	xfs_attr_leaf_name_local_t 	*local;
> +	xfs_attr_leaf_name_remote_t 	*remote;
> +	__uint32_t			bs = mp->m_sb.sb_blocksize;
> +
>  
>  	leaf = (xfs_attr_leafblock_t *)block;
>  
> -	if (be16_to_cpu(leaf->hdr.info.magic) != XFS_ATTR_LEAF_MAGIC) {
> +	/* Get header; accounts for crc & non-crc */
> +	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &hdr, leaf);
> +
> +	/* Remote attributes */
> +	if ((hdr.magic != XFS_ATTR_LEAF_MAGIC) &&
> +	    (hdr.magic != XFS_ATTR3_LEAF_MAGIC)) {
>  		for (i = 0; i < attr_data.remote_val_count; i++) {
> -			/* XXX: need to handle CRC headers */
>  			if (attr_data.remote_vals[i] == offset)
> -				memset(block, 0, mp->m_sb.sb_blocksize);
> +				/* magic to handle attr and attr3 */
> +				memset(block +
> +					(bs - XFS_ATTR3_RMT_BUF_SPACE(mp, bs)),
> +				      0, XFS_ATTR3_RMT_BUF_SPACE(mp, bs));
>  		}
>  		return;
>  	}
>  
> -	nentries = be16_to_cpu(leaf->hdr.count);
> +	nentries = hdr.count;
> +
>  	if (nentries * sizeof(xfs_attr_leaf_entry_t) +
> -			sizeof(xfs_attr_leaf_hdr_t) > mp->m_sb.sb_blocksize) {
> +			xfs_attr3_leaf_hdr_size(leaf) >
> +				XFS_ATTR3_RMT_BUF_SPACE(mp, bs)) {
>  		if (show_warnings)
>  			print_warning("invalid attr count in inode %llu",
>  					(long long)cur_ino);
>  		return;
>  	}
>  
> -	for (i = 0, entry = &leaf->entries[0]; i < nentries; i++, entry++) {
> +	entry = xfs_attr3_leaf_entryp(leaf);
> +
> +	for (i = 0; i < nentries; i++, entry++) {
>  		if (be16_to_cpu(entry->nameidx) > mp->m_sb.sb_blocksize) {
>  			if (show_warnings)
>  				print_warning(
> 
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