Re: [PATCH v2] udf: reduce leakage of blocks related to named streams
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.
> > >
> > > } 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
SUSE Labs, CR
Re: [PATCH v2] udf: reduce leakage of blocks related to named streams
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.
} 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
Re: [PATCH v2] udf: reduce leakage of blocks related to named streams
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
>
> --- 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 {
> unsignedi_efe : 1; /* extendedFileEntry */
> unsignedi_use : 1; /* unallocSpaceEntry */
> unsignedi_strat4096 : 1;
> - unsignedreserved : 26;
> + unsignedi_streamdir : 1;
> + unsignedreserved : 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 = 0x;
> + ei->i_locStreamdir.partitionReferenceNum = 0x;
I don't think you need to initialize i_locStreamdir when i_streamdir is
already set to 0...
> init_rwsem(>i_data_sem);
> ei->cached_extent.lstart = -1;
> spin_lock_init(>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 = 0x;
> + iinfo->i_locStreamdir.partitionReferenceNum = 0x;
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
SUSE Labs, CR
