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Subject[PATCH v2] udf: reduce leakage of blocks related to named streams
Date
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);
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