[PATCH v2] udf: reduce leakage of blocks related to named streams

[PATCH v2] udf: reduce leakage of blocks related to named streams

[Steven J. Magnani]

Windows is capable of creating UDF files having named streams.
One example is the "Zone.Identifier" stream attached automatically
to files downloaded from a network. See:
  https://msdn.microsoft.com/en-us/library/dn392609.aspx

Modification of a file having one or more named streams in Linux causes
the stream directory to become detached from the file, essentially leaking
all blocks pertaining to the file's streams.

Fix by saving off information about an inode's streams when reading it,
for later use when its on-disk data is updated.

Changes from v1:
Remove modifications that would limit leakage of all inode blocks
on deletion.
This restricts the patch to preservation of stream data during inode
modification.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>

--- a/fs/udf/udf_i.h	2019-07-26 11:35:28.257563879 -0500
+++ b/fs/udf/udf_i.h	2019-08-06 14:35:55.579654263 -0500
@@ -42,12 +42,15 @@ struct udf_inode_info {
 	unsigned		i_efe : 1;	/* extendedFileEntry */
 	unsigned		i_use : 1;	/* unallocSpaceEntry */
 	unsigned		i_strat4096 : 1;
-	unsigned		reserved : 26;
+	unsigned		i_streamdir : 1;
+	unsigned		reserved : 25;
 	union {
 		struct short_ad	*i_sad;
 		struct long_ad		*i_lad;
 		__u8		*i_data;
 	} i_ext;
+	struct kernel_lb_addr	i_locStreamdir;
+	__u64			i_lenStreams;
 	struct rw_semaphore	i_data_sem;
 	struct udf_ext_cache cached_extent;
 	/* Spinlock for protecting extent cache */
--- a/fs/udf/super.c	2019-07-26 11:35:28.253563792 -0500
+++ b/fs/udf/super.c	2019-08-06 15:04:30.851086957 -0500
@@ -151,9 +151,13 @@ static struct inode *udf_alloc_inode(str
 
 	ei->i_unique = 0;
 	ei->i_lenExtents = 0;
+	ei->i_lenStreams = 0;
 	ei->i_next_alloc_block = 0;
 	ei->i_next_alloc_goal = 0;
 	ei->i_strat4096 = 0;
+	ei->i_streamdir = 0;
+	ei->i_locStreamdir.logicalBlockNum = 0xFFFFFFFF;
+	ei->i_locStreamdir.partitionReferenceNum = 0xFFFF;
 	init_rwsem(&ei->i_data_sem);
 	ei->cached_extent.lstart = -1;
 	spin_lock_init(&ei->i_extent_cache_lock);
--- a/fs/udf/inode.c	2019-07-26 11:35:28.253563792 -0500
+++ b/fs/udf/inode.c	2019-08-06 15:04:30.851086957 -0500
@@ -1485,6 +1485,10 @@ reread:
 		iinfo->i_lenEAttr = le32_to_cpu(fe->lengthExtendedAttr);
 		iinfo->i_lenAlloc = le32_to_cpu(fe->lengthAllocDescs);
 		iinfo->i_checkpoint = le32_to_cpu(fe->checkpoint);
+		iinfo->i_streamdir = 0;
+		iinfo->i_lenStreams = 0;
+		iinfo->i_locStreamdir.logicalBlockNum = 0xFFFFFFFF;
+		iinfo->i_locStreamdir.partitionReferenceNum = 0xFFFF;
 	} else {
 		inode->i_blocks = le64_to_cpu(efe->logicalBlocksRecorded) <<
 		    (inode->i_sb->s_blocksize_bits - 9);
@@ -1498,6 +1502,16 @@ reread:
 		iinfo->i_lenEAttr = le32_to_cpu(efe->lengthExtendedAttr);
 		iinfo->i_lenAlloc = le32_to_cpu(efe->lengthAllocDescs);
 		iinfo->i_checkpoint = le32_to_cpu(efe->checkpoint);
+
+		/* Named streams */
+		iinfo->i_streamdir = (efe->streamDirectoryICB.extLength != 0);
+		iinfo->i_locStreamdir =
+			lelb_to_cpu(efe->streamDirectoryICB.extLocation);
+		iinfo->i_lenStreams = le64_to_cpu(efe->objectSize);
+		if (iinfo->i_lenStreams >= inode->i_size)
+			iinfo->i_lenStreams -= inode->i_size;
+		else
+			iinfo->i_lenStreams = 0;
 	}
 	inode->i_generation = iinfo->i_unique;
 
@@ -1760,9 +1774,19 @@ static int udf_update_inode(struct inode
 		       iinfo->i_ext.i_data,
 		       inode->i_sb->s_blocksize -
 					sizeof(struct extendedFileEntry));
-		efe->objectSize = cpu_to_le64(inode->i_size);
+		efe->objectSize =
+			cpu_to_le64(inode->i_size + iinfo->i_lenStreams);
 		efe->logicalBlocksRecorded = cpu_to_le64(lb_recorded);
 
+		if (iinfo->i_streamdir) {
+			struct long_ad *icb_lad = &efe->streamDirectoryICB;
+
+			icb_lad->extLocation =
+				cpu_to_lelb(iinfo->i_locStreamdir);
+			icb_lad->extLength =
+				cpu_to_le32(inode->i_sb->s_blocksize);
+		}
+
 		udf_adjust_time(iinfo, inode->i_atime);
 		udf_adjust_time(iinfo, inode->i_mtime);
 		udf_adjust_time(iinfo, inode->i_ctime);

Re: [PATCH v2] udf: reduce leakage of blocks related to named streams

[Jan Kara]

On Wed 14-08-19 07:50:02,  Steven J. Magnani  wrote:
> Windows is capable of creating UDF files having named streams.
> One example is the "Zone.Identifier" stream attached automatically
> to files downloaded from a network. See:
>   https://msdn.microsoft.com/en-us/library/dn392609.aspx
> 
> Modification of a file having one or more named streams in Linux causes
> the stream directory to become detached from the file, essentially leaking
> all blocks pertaining to the file's streams.
> 
> Fix by saving off information about an inode's streams when reading it,
> for later use when its on-disk data is updated.

Thanks for the patch! I agree with the idea of this patch. Just some
small comments below.

> Changes from v1:
> Remove modifications that would limit leakage of all inode blocks
> on deletion.
> This restricts the patch to preservation of stream data during inode
> modification.

Please put patch changelog below Signed-off-by and --- delimiter so that it
does not get included in the final commit message when I do git-am.

> Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
> 
> --- a/fs/udf/udf_i.h	2019-07-26 11:35:28.257563879 -0500
> +++ b/fs/udf/udf_i.h	2019-08-06 14:35:55.579654263 -0500
> @@ -42,12 +42,15 @@ struct udf_inode_info {
>  	unsigned		i_efe : 1;	/* extendedFileEntry */
>  	unsigned		i_use : 1;	/* unallocSpaceEntry */
>  	unsigned		i_strat4096 : 1;
> -	unsigned		reserved : 26;
> +	unsigned		i_streamdir : 1;
> +	unsigned		reserved : 25;
>  	union {
>  		struct short_ad	*i_sad;
>  		struct long_ad		*i_lad;
>  		__u8		*i_data;
>  	} i_ext;
> +	struct kernel_lb_addr	i_locStreamdir;
> +	__u64			i_lenStreams;
>  	struct rw_semaphore	i_data_sem;
>  	struct udf_ext_cache cached_extent;
>  	/* Spinlock for protecting extent cache */
> --- a/fs/udf/super.c	2019-07-26 11:35:28.253563792 -0500
> +++ b/fs/udf/super.c	2019-08-06 15:04:30.851086957 -0500
> @@ -151,9 +151,13 @@ static struct inode *udf_alloc_inode(str
>  
>  	ei->i_unique = 0;
>  	ei->i_lenExtents = 0;
> +	ei->i_lenStreams = 0;
>  	ei->i_next_alloc_block = 0;
>  	ei->i_next_alloc_goal = 0;
>  	ei->i_strat4096 = 0;
> +	ei->i_streamdir = 0;
> +	ei->i_locStreamdir.logicalBlockNum = 0xFFFFFFFF;
> +	ei->i_locStreamdir.partitionReferenceNum = 0xFFFF;

I don't think you need to initialize i_locStreamdir when i_streamdir is
already set to 0...

>  	init_rwsem(&ei->i_data_sem);
>  	ei->cached_extent.lstart = -1;
>  	spin_lock_init(&ei->i_extent_cache_lock);
> --- a/fs/udf/inode.c	2019-07-26 11:35:28.253563792 -0500
> +++ b/fs/udf/inode.c	2019-08-06 15:04:30.851086957 -0500
> @@ -1485,6 +1485,10 @@ reread:
>  		iinfo->i_lenEAttr = le32_to_cpu(fe->lengthExtendedAttr);
>  		iinfo->i_lenAlloc = le32_to_cpu(fe->lengthAllocDescs);
>  		iinfo->i_checkpoint = le32_to_cpu(fe->checkpoint);
> +		iinfo->i_streamdir = 0;
> +		iinfo->i_lenStreams = 0;
> +		iinfo->i_locStreamdir.logicalBlockNum = 0xFFFFFFFF;
> +		iinfo->i_locStreamdir.partitionReferenceNum = 0xFFFF;

Ditto here...

>  	} else {
>  		inode->i_blocks = le64_to_cpu(efe->logicalBlocksRecorded) <<
>  		    (inode->i_sb->s_blocksize_bits - 9);
> @@ -1498,6 +1502,16 @@ reread:
>  		iinfo->i_lenEAttr = le32_to_cpu(efe->lengthExtendedAttr);
>  		iinfo->i_lenAlloc = le32_to_cpu(efe->lengthAllocDescs);
>  		iinfo->i_checkpoint = le32_to_cpu(efe->checkpoint);
> +
> +		/* Named streams */
> +		iinfo->i_streamdir = (efe->streamDirectoryICB.extLength != 0);
> +		iinfo->i_locStreamdir =
> +			lelb_to_cpu(efe->streamDirectoryICB.extLocation);
> +		iinfo->i_lenStreams = le64_to_cpu(efe->objectSize);
> +		if (iinfo->i_lenStreams >= inode->i_size)
> +			iinfo->i_lenStreams -= inode->i_size;
> +		else
> +			iinfo->i_lenStreams = 0;

Hum, maybe you could just have i_objectSize instead of i_lenStreams? You
use the field just to preserve objectSize anyway so there's no point in
complicating it.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH v2] udf: reduce leakage of blocks related to named streams

[Steve Magnani]

Jan -


On 8/15/19 7:42 AM, Jan Kara wrote:
> On Wed 14-08-19 07:50:02,  Steven J. Magnani  wrote:
>> Windows is capable of creating UDF files having named streams.
>> One example is the "Zone.Identifier" stream attached automatically
>> to files downloaded from a network. See:
>>    https://msdn.microsoft.com/en-us/library/dn392609.aspx
>>
>> Modification of a file having one or more named streams in Linux causes
>> the stream directory to become detached from the file, essentially leaking
>> all blocks pertaining to the file's streams.
>>
>> Fix by saving off information about an inode's streams when reading it,
>> for later use when its on-disk data is updated.
>> <snip>
>>   	} else {
>>   		inode->i_blocks = le64_to_cpu(efe->logicalBlocksRecorded) <<
>>   		    (inode->i_sb->s_blocksize_bits - 9);
>> @@ -1498,6 +1502,16 @@ reread:
>>   		iinfo->i_lenEAttr = le32_to_cpu(efe->lengthExtendedAttr);
>>   		iinfo->i_lenAlloc = le32_to_cpu(efe->lengthAllocDescs);
>>   		iinfo->i_checkpoint = le32_to_cpu(efe->checkpoint);
>> +
>> +		/* Named streams */
>> +		iinfo->i_streamdir = (efe->streamDirectoryICB.extLength != 0);
>> +		iinfo->i_locStreamdir =
>> +			lelb_to_cpu(efe->streamDirectoryICB.extLocation);
>> +		iinfo->i_lenStreams = le64_to_cpu(efe->objectSize);
>> +		if (iinfo->i_lenStreams >= inode->i_size)
>> +			iinfo->i_lenStreams -= inode->i_size;
>> +		else
>> +			iinfo->i_lenStreams = 0;
> Hum, maybe you could just have i_objectSize instead of i_lenStreams? You
> use the field just to preserve objectSize anyway so there's no point in
> complicating it.
>

I started making this change and found that it actually complicates things more,
by forcing the driver to update i_objectSize everywhere that i_size is changed.
Are you sure this is what you want?

------------------------------------------------------------------------
  Steven J. Magnani               "I claim this network for MARS!
  www.digidescorp.com              Earthling, return my space modulator!"

  #include <standard.disclaimer>

Re: [PATCH v2] udf: reduce leakage of blocks related to named streams

[Jan Kara]

On Mon 19-08-19 07:10:24, Steve Magnani wrote:
> Jan -
> 
> 
> On 8/15/19 7:42 AM, Jan Kara wrote:
> > On Wed 14-08-19 07:50:02,  Steven J. Magnani  wrote:
> > > Windows is capable of creating UDF files having named streams.
> > > One example is the "Zone.Identifier" stream attached automatically
> > > to files downloaded from a network. See:
> > >    https://msdn.microsoft.com/en-us/library/dn392609.aspx
> > > 
> > > Modification of a file having one or more named streams in Linux causes
> > > the stream directory to become detached from the file, essentially leaking
> > > all blocks pertaining to the file's streams.
> > > 
> > > Fix by saving off information about an inode's streams when reading it,
> > > for later use when its on-disk data is updated.
> > > <snip>
> > >   	} else {
> > >   		inode->i_blocks = le64_to_cpu(efe->logicalBlocksRecorded) <<
> > >   		    (inode->i_sb->s_blocksize_bits - 9);
> > > @@ -1498,6 +1502,16 @@ reread:
> > >   		iinfo->i_lenEAttr = le32_to_cpu(efe->lengthExtendedAttr);
> > >   		iinfo->i_lenAlloc = le32_to_cpu(efe->lengthAllocDescs);
> > >   		iinfo->i_checkpoint = le32_to_cpu(efe->checkpoint);
> > > +
> > > +		/* Named streams */
> > > +		iinfo->i_streamdir = (efe->streamDirectoryICB.extLength != 0);
> > > +		iinfo->i_locStreamdir =
> > > +			lelb_to_cpu(efe->streamDirectoryICB.extLocation);
> > > +		iinfo->i_lenStreams = le64_to_cpu(efe->objectSize);
> > > +		if (iinfo->i_lenStreams >= inode->i_size)
> > > +			iinfo->i_lenStreams -= inode->i_size;
> > > +		else
> > > +			iinfo->i_lenStreams = 0;
> > Hum, maybe you could just have i_objectSize instead of i_lenStreams? You
> > use the field just to preserve objectSize anyway so there's no point in
> > complicating it.
> > 
> 
> I started making this change and found that it actually complicates things more,
> by forcing the driver to update i_objectSize everywhere that i_size is changed.
> Are you sure this is what you want?

Aha, that's a good point! No, in that case what you did was better. I'll
just take your v2 patch then, I can make the other minor adjustments I was
suggesting when applying the patch. Thanks for looking into this!

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR