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SubjectRe: [WIP PATCH 1/4] udf: Do not access LVIDIU revision members when they are not filled
On Monday 13 January 2020 13:00:49 Jan Kara wrote:
> On Sun 12-01-20 18:59:30, Pali Rohár wrote:
> > minUDFReadRev, minUDFWriteRev and maxUDFWriteRev members were introduced in
> > UDF 1.02. Previous UDF revisions used that area for implementation specific
> > data. So in this case do not touch these members.
> >
> > To check if LVIDIU contain revisions members, first read UDF revision from
> > LVD. If revision is at least 1.02 LVIDIU should contain revision members.
> >
> > This change should fix mounting UDF 1.01 images in R/W mode. Kernel would
> > not touch, read overwrite implementation specific area of LVIDIU.
> >
> > Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
>
> Maybe we could store the fs revision in the superblock as well to avoid
> passing the udf_rev parameter?

Unfortunately not. Function udf_verify_domain_identifier() is called
also when parsing FSD. FSD is stored on partition map and e.g. Metadata
partition map depends on UDF revision. So it is not a good idea to
overwrite UDF revision from FSD. This is reason why I decided to use
initial UDF revision number only from LVD.

But whole stuff around UDF revision is a mess. UDF revision is stored on
these locations:

main LVD
reserve LVD
main IUVD
reserve IUVD
FSD

And optionally (when specific UDF feature is used) also on:

sparable partition map 1.50+
virtual partition map 1.50+
all sparing tables 1.50+
VAT 1.50

Plus tuple minimal read, minimal write, maximal write UDF revision is
stored on:

LVIDIU 1.02+
VAT 2.00+

VAT in 2.00+ format overrides information stored on LVIDIU.

> Also this patch contains several lines over 80 columns.

Ok, this is easy to solve.

> Honza
>
> > ---
> > fs/udf/super.c | 37 ++++++++++++++++++++++++++-----------
> > fs/udf/udf_sb.h | 3 +++
> > 2 files changed, 29 insertions(+), 11 deletions(-)
> >
> > diff --git a/fs/udf/super.c b/fs/udf/super.c
> > index 2d0b90800..8df6e9962 100644
> > --- a/fs/udf/super.c
> > +++ b/fs/udf/super.c
> > @@ -765,7 +765,7 @@ static int udf_check_vsd(struct super_block *sb)
> > }
> >
> > static int udf_verify_domain_identifier(struct super_block *sb,
> > - struct regid *ident, char *dname)
> > + struct regid *ident, char *dname, u16 *udf_rev)
> > {
> > struct domainIdentSuffix *suffix;
> >
> > @@ -779,6 +779,8 @@ static int udf_verify_domain_identifier(struct super_block *sb,
> > goto force_ro;
> > }
> > suffix = (struct domainIdentSuffix *)ident->identSuffix;
> > + if (udf_rev)
> > + *udf_rev = le16_to_cpu(suffix->UDFRevision);
> > if ((suffix->domainFlags & DOMAIN_FLAGS_HARD_WRITE_PROTECT) ||
> > (suffix->domainFlags & DOMAIN_FLAGS_SOFT_WRITE_PROTECT)) {
> > if (!sb_rdonly(sb)) {
> > @@ -801,7 +803,7 @@ static int udf_load_fileset(struct super_block *sb, struct fileSetDesc *fset,
> > {
> > int ret;
> >
> > - ret = udf_verify_domain_identifier(sb, &fset->domainIdent, "file set");
> > + ret = udf_verify_domain_identifier(sb, &fset->domainIdent, "file set", NULL);
> > if (ret < 0)
> > return ret;
> >
> > @@ -1404,7 +1406,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
> > }
> >
> > ret = udf_verify_domain_identifier(sb, &lvd->domainIdent,
> > - "logical volume");
> > + "logical volume", &sbi->s_lvd_udfrev);
> > if (ret)
> > goto out_bh;
> > ret = udf_sb_alloc_partition_maps(sb, le32_to_cpu(lvd->numPartitionMaps));
> > @@ -2055,12 +2057,19 @@ static void udf_close_lvid(struct super_block *sb)
> > mutex_lock(&sbi->s_alloc_mutex);
> > lvidiu->impIdent.identSuffix[0] = UDF_OS_CLASS_UNIX;
> > lvidiu->impIdent.identSuffix[1] = UDF_OS_ID_LINUX;
> > - if (UDF_MAX_WRITE_VERSION > le16_to_cpu(lvidiu->maxUDFWriteRev))
> > - lvidiu->maxUDFWriteRev = cpu_to_le16(UDF_MAX_WRITE_VERSION);
> > - if (sbi->s_udfrev > le16_to_cpu(lvidiu->minUDFReadRev))
> > - lvidiu->minUDFReadRev = cpu_to_le16(sbi->s_udfrev);
> > - if (sbi->s_udfrev > le16_to_cpu(lvidiu->minUDFWriteRev))
> > - lvidiu->minUDFWriteRev = cpu_to_le16(sbi->s_udfrev);
> > +
> > + /* minUDFReadRev, minUDFWriteRev and maxUDFWriteRev members were
> > + * introduced in UDF 1.02. Previous UDF revisions used that area for
> > + * implementation specific data. So in this case do not touch it. */
> > + if (sbi->s_lvd_udfrev >= 0x0102) {
> > + if (UDF_MAX_WRITE_VERSION > le16_to_cpu(lvidiu->maxUDFWriteRev))
> > + lvidiu->maxUDFWriteRev = cpu_to_le16(UDF_MAX_WRITE_VERSION);
> > + if (sbi->s_udfrev > le16_to_cpu(lvidiu->minUDFReadRev))
> > + lvidiu->minUDFReadRev = cpu_to_le16(sbi->s_udfrev);
> > + if (sbi->s_udfrev > le16_to_cpu(lvidiu->minUDFWriteRev))
> > + lvidiu->minUDFWriteRev = cpu_to_le16(sbi->s_udfrev);
> > + }
> > +
> > if (!UDF_QUERY_FLAG(sb, UDF_FLAG_INCONSISTENT))
> > lvid->integrityType = cpu_to_le32(LVID_INTEGRITY_TYPE_CLOSE);
> >
> > @@ -2220,8 +2229,14 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
> > ret = -EINVAL;
> > goto error_out;
> > }
> > - minUDFReadRev = le16_to_cpu(lvidiu->minUDFReadRev);
> > - minUDFWriteRev = le16_to_cpu(lvidiu->minUDFWriteRev);
> > +
> > + if (sbi->s_lvd_udfrev >= 0x0102) { /* minUDFReadRev and minUDFWriteRev were introduced in UDF 1.02 */
> > + minUDFReadRev = le16_to_cpu(lvidiu->minUDFReadRev);
> > + minUDFWriteRev = le16_to_cpu(lvidiu->minUDFWriteRev);
> > + } else {
> > + minUDFReadRev = minUDFWriteRev = sbi->s_lvd_udfrev;
> > + }
> > +
> > if (minUDFReadRev > UDF_MAX_READ_VERSION) {
> > udf_err(sb, "minUDFReadRev=%x (max is %x)\n",
> > minUDFReadRev,
> > diff --git a/fs/udf/udf_sb.h b/fs/udf/udf_sb.h
> > index 3d83be54c..6bd0d4430 100644
> > --- a/fs/udf/udf_sb.h
> > +++ b/fs/udf/udf_sb.h
> > @@ -137,6 +137,9 @@ struct udf_sb_info {
> > /* Fileset Info */
> > __u16 s_serial_number;
> >
> > + /* LVD UDF revision filled to media at format time */
> > + __u16 s_lvd_udfrev;
> > +
> > /* highest UDF revision we have recorded to this media */
> > __u16 s_udfrev;
> >
> > --
> > 2.20.1
> >

--
Pali Rohár
pali.rohar@gmail.com
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