Re: [PATCH v6 3/3] mkfs: make use of xfs_validate_stripe_geometry()

[Gao Xiang <hsiangkao@redhat.com>]

Hi Eric,

On Mon, Feb 15, 2021 at 07:04:25PM -0600, Eric Sandeen wrote:
> On 10/12/20 11:06 PM, Gao Xiang wrote:
> > Check stripe numbers in calc_stripe_factors() by using
> > xfs_validate_stripe_geometry().
> > 
> > Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
> 
> Hm, unless I have made a mistake, this seems to allow an invalid
> stripe specification.
> 
> Without this patch, this fails:
> 
> # mkfs/mkfs.xfs -f -d su=4097,sw=1 /dev/loop0
> data su must be a multiple of the sector size (512)
> 
> With the patch:
> 
> # mkfs/mkfs.xfs -f -d su=4097,sw=1 /dev/loop0
> meta-data=/dev/loop0             isize=512    agcount=8, agsize=32768 blks
>          =                       sectsz=512   attr=2, projid32bit=1
>          =                       crc=1        finobt=1, sparse=1, rmapbt=0
>          =                       reflink=1    bigtime=0
> data     =                       bsize=4096   blocks=262144, imaxpct=25
>          =                       sunit=1      swidth=1 blks
> naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
> log      =internal log           bsize=4096   blocks=2560, version=2
>          =                       sectsz=512   sunit=1 blks, lazy-count=1
> realtime =none                   extsz=4096   blocks=0, rtextents=0
> Discarding blocks...Done.
> 
> When you are back from holiday, can you check? No big rush.

I'm back from holiday today. I think the problem is in
"if (dsu || dsw) {" it turns into "dsunit  = (int)BTOBBT(dsu);" anyway,
and then if (!libxfs_validate_stripe_geometry(NULL, BBTOB(dsunit),
					     BBTOB(dswidth), cfg->sectorsize, false))

so dsu isn't checked with sectorsize in advance before it turns into BB.

the fix seems simple though,
1) turn dsunit and dswidth into bytes rather than BB, but I have no idea the range of
   these 2 varibles, since I saw "if (big_dswidth > INT_MAX) {" but the big_dswidth
   was also in BB as well, if we turn these into bytes, and such range cannot be
   guarunteed...
2) recover the previous code snippet and check dsu in advance:
		if (dsu % cfg->sectorsize) {
			fprintf(stderr,
_("data su must be a multiple of the sector size (%d)\n"), cfg->sectorsize);
			usage();
		}

btw, do we have some range test about these variables? I could rearrange the code
snippet, but I'm not sure if it could introduce some new potential regression as well...

Thanks,
Gao Xiang

> 
> Thanks,
> -Eric
> 
> > ---
> >  libxfs/libxfs_api_defs.h |  1 +
> >  mkfs/xfs_mkfs.c          | 23 +++++++----------------
> >  2 files changed, 8 insertions(+), 16 deletions(-)
> > 
> > diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
> > index e7e42e93..306d0deb 100644
> > --- a/libxfs/libxfs_api_defs.h
> > +++ b/libxfs/libxfs_api_defs.h
> > @@ -188,6 +188,7 @@
> >  #define xfs_trans_roll_inode		libxfs_trans_roll_inode
> >  #define xfs_trans_roll			libxfs_trans_roll
> >  
> > +#define xfs_validate_stripe_geometry	libxfs_validate_stripe_geometry
> >  #define xfs_verify_agbno		libxfs_verify_agbno
> >  #define xfs_verify_agino		libxfs_verify_agino
> >  #define xfs_verify_cksum		libxfs_verify_cksum
> > diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> > index 8fe149d7..aec40c1f 100644
> > --- a/mkfs/xfs_mkfs.c
> > +++ b/mkfs/xfs_mkfs.c
> > @@ -2305,12 +2305,6 @@ _("both data su and data sw options must be specified\n"));
> >  			usage();
> >  		}
> >  
> > -		if (dsu % cfg->sectorsize) {
> > -			fprintf(stderr,
> > -_("data su must be a multiple of the sector size (%d)\n"), cfg->sectorsize);
> > -			usage();
> > -		}
> > -
> >  		dsunit  = (int)BTOBBT(dsu);
> >  		big_dswidth = (long long int)dsunit * dsw;
> >  		if (big_dswidth > INT_MAX) {
> > @@ -2322,13 +2316,9 @@ _("data stripe width (%lld) is too large of a multiple of the data stripe unit (
> >  		dswidth = big_dswidth;
> >  	}
> >  
> > -	if ((dsunit && !dswidth) || (!dsunit && dswidth) ||
> > -	    (dsunit && (dswidth % dsunit != 0))) {
> > -		fprintf(stderr,
> > -_("data stripe width (%d) must be a multiple of the data stripe unit (%d)\n"),
> > -			dswidth, dsunit);
> > +	if (!libxfs_validate_stripe_geometry(NULL, BBTOB(dsunit), BBTOB(dswidth),
> > +					     cfg->sectorsize, false))
> >  		usage();
> > -	}
> >  
> >  	/* If sunit & swidth were manually specified as 0, same as noalign */
> >  	if ((cli_opt_set(&dopts, D_SUNIT) || cli_opt_set(&dopts, D_SU)) &&
> > @@ -2344,11 +2334,12 @@ _("data stripe width (%d) must be a multiple of the data stripe unit (%d)\n"),
> >  
> >  	/* if no stripe config set, use the device default */
> >  	if (!dsunit) {
> > -		/* Ignore nonsense from device.  XXX add more validation */
> > -		if (ft->dsunit && ft->dswidth == 0) {
> > +		/* Ignore nonsense from device report. */
> > +		if (!libxfs_validate_stripe_geometry(NULL, BBTOB(ft->dsunit),
> > +				BBTOB(ft->dswidth), 0, true)) {
> >  			fprintf(stderr,
> > -_("%s: Volume reports stripe unit of %d bytes and stripe width of 0, ignoring.\n"),
> > -				progname, BBTOB(ft->dsunit));
> > +_("%s: Volume reports invalid stripe unit (%d) and stripe width (%d), ignoring.\n"),
> > +				progname, BBTOB(ft->dsunit), BBTOB(ft->dswidth));
> >  			ft->dsunit = 0;
> >  			ft->dswidth = 0;
> >  		} else {
> > 
>