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udf: Prevent write-unsupported filesystem to be remounted read-write

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There are certain filesystem features which we support for reading but
not for writing. We properly refuse to mount such filesystems read-write
however for some features (such as read-only partitions), we don't check
for these features when remounting the filesystem from read-only to
read-write. Thus such filesystems could be remounted read-write leading
to strange behavior (most likely crashes).

Fix the problem by marking in superblock whether the filesystem has some
features that are supported in read-only mode and check this flag during
remount.

Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2018-09-06 15:56:10 +02:00
parent 59fed3bf8a
commit a9ad01bc75
2 changed files with 18 additions and 14 deletions
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30
fs/udf/super.c
View File

@ -613,14 +613,11 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
struct udf_options uopt;
struct udf_sb_info *sbi = UDF_SB(sb);
int error = 0;
struct logicalVolIntegrityDescImpUse *lvidiu = udf_sb_lvidiu(sb);
if (!(*flags & SB_RDONLY) && UDF_QUERY_FLAG(sb, UDF_FLAG_RW_INCOMPAT))
return -EACCES;
sync_filesystem(sb);
if (lvidiu) {
int write_rev = le16_to_cpu(lvidiu->minUDFWriteRev);
if (write_rev > UDF_MAX_WRITE_VERSION && !(*flags & SB_RDONLY))
return -EACCES;
}
uopt.flags = sbi->s_flags;
uopt.uid = sbi->s_uid;
@ -1257,6 +1254,7 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block)
ret = -EACCES;
goto out_bh;
}
UDF_SET_FLAG(sb, UDF_FLAG_RW_INCOMPAT);
ret = udf_load_vat(sb, i, type1_idx);
if (ret < 0)
goto out_bh;
@ -2155,10 +2153,12 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
UDF_MAX_READ_VERSION);
ret = -EINVAL;
goto error_out;
} else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION &&
!sb_rdonly(sb)) {
ret = -EACCES;
goto error_out;
} else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION) {
if (!sb_rdonly(sb)) {
ret = -EACCES;
goto error_out;
}
UDF_SET_FLAG(sb, UDF_FLAG_RW_INCOMPAT);
}
sbi->s_udfrev = minUDFWriteRev;
@ -2176,10 +2176,12 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
}
if (sbi->s_partmaps[sbi->s_partition].s_partition_flags &
UDF_PART_FLAG_READ_ONLY &&
!sb_rdonly(sb)) {
ret = -EACCES;
goto error_out;
UDF_PART_FLAG_READ_ONLY) {
if (!sb_rdonly(sb)) {
ret = -EACCES;
goto error_out;
}
UDF_SET_FLAG(sb, UDF_FLAG_RW_INCOMPAT);
}
if (udf_find_fileset(sb, &fileset, &rootdir)) {

2
fs/udf/udf_sb.h
View File

@ -30,6 +30,8 @@
#define UDF_FLAG_LASTBLOCK_SET 16
#define UDF_FLAG_BLOCKSIZE_SET 17
#define UDF_FLAG_INCONSISTENT 18
#define UDF_FLAG_RW_INCOMPAT 19 /* Set when we find RW incompatible
* feature */
#define UDF_PART_FLAG_UNALLOC_BITMAP 0x0001
#define UDF_PART_FLAG_UNALLOC_TABLE 0x0002