udf: reduce leakage of blocks related to named streams

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.

Link: https://lore.kernel.org/r/20190814125002.10869-1-steve@digidescorp.com
Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 9bb1831..54eee39 100644 (file)
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -1485,6 +1485,8 @@ 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;
        } else {
                inode->i_blocks = le64_to_cpu(efe->logicalBlocksRecorded) <<
                    (inode->i_sb->s_blocksize_bits - 9);
@@ -1498,6 +1500,16 @@ 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 +1772,19 @@ static int udf_update_inode(struct inode *inode, int do_sync)
                       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);

diff --git a/fs/udf/super.c b/fs/udf/super.c
index f34e06b..00e2d71 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -151,9 +151,11 @@ static struct inode *udf_alloc_inode(struct super_block *sb)
 
        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;
        init_rwsem(&ei->i_data_sem);
        ei->cached_extent.lstart = -1;
        spin_lock_init(&ei->i_extent_cache_lock);

diff --git a/fs/udf/udf_i.h b/fs/udf/udf_i.h
index 2ef0e21..00d773d 100644 (file)
--- a/fs/udf/udf_i.h
+++ b/fs/udf/udf_i.h
@@ -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 */