Differential D24596 Diff 71727 sys/fs/msdosfs/msdosfs_vnops.c

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sys/fs/msdosfs/msdosfs_vnops.c

Show First 20 Lines • Show All 514 Lines • ▼ Show 20 Lines	#endif
return (deupdat(dep, 0));		return (deupdat(dep, 0));
}		}

static int		static int
msdosfs_read(struct vop_read_args *ap)		msdosfs_read(struct vop_read_args *ap)
{		{
int error = 0;		int error = 0;
int blsize;		int blsize;
int isadir;
ssize_t orig_resid;		ssize_t orig_resid;
u_int n;		u_int n;
u_long diff;		u_long diff;
u_long on;		u_long on;
daddr_t lbn;		daddr_t lbn;
daddr_t rablock;		daddr_t rablock;
int rasize;		int rasize;
int seqcount;		int seqcount;
struct buf *bp;		struct buf *bp;
struct vnode *vp = ap->a_vp;		struct vnode *vp = ap->a_vp;
struct denode *dep = VTODE(vp);		struct denode *dep = VTODE(vp);
struct msdosfsmount *pmp = dep->de_pmp;		struct msdosfsmount *pmp = dep->de_pmp;
struct uio *uio = ap->a_uio;		struct uio *uio = ap->a_uio;

/*		/*
		* This check duplicates a similar check on the vnode that occurs up in
		* the VFS layer, but it's perhaps necessary. msdosfs, in particular,
		* are often read from untrusted sources or synthesized on the fly, so
		* it does not hurt to ensure that the metadata here is consistent with
		* our assumption having entered msdosfs_read. This may not be
		* exceptional, so we reject it with an appropriate error rather than
		* asserting it or panicking.
		*/
		if ((dep->de_Attributes & ATTR_DIRECTORY) != 0)
		return (EISDIR);

		/*
* If they didn't ask for any data, then we are done.		* If they didn't ask for any data, then we are done.
*/		*/
orig_resid = uio->uio_resid;		orig_resid = uio->uio_resid;
if (orig_resid == 0)		if (orig_resid == 0)
return (0);		return (0);

/*		/*
* The caller is supposed to ensure that		* The caller is supposed to ensure that
* uio->uio_offset >= 0 and uio->uio_resid >= 0.		* uio->uio_offset >= 0 and uio->uio_resid >= 0.
* We don't need to check for large offsets as in ffs because		* We don't need to check for large offsets as in ffs because
* dep->de_FileSize <= MSDOSFS_FILESIZE_MAX < OFF_MAX, so large		* dep->de_FileSize <= MSDOSFS_FILESIZE_MAX < OFF_MAX, so large
* offsets cannot cause overflow even in theory.		* offsets cannot cause overflow even in theory.
*/		*/

seqcount = ap->a_ioflag >> IO_SEQSHIFT;		seqcount = ap->a_ioflag >> IO_SEQSHIFT;

isadir = dep->de_Attributes & ATTR_DIRECTORY;
kibUnsubmitted Not Done Inline Actions I think it is still worth keep this check somehow, either as KASSERT, or just as `return (EISDIR)`. After all, msdosfs is often read from untrusted sources or even synthesized on fly. There of course will be a redundancy with the upper-level check that in principle looked at the same data, but for msdosfs it is better to recheck. kib: I think it is still worth keep this check somehow, either as KASSERT, or just as `return…
kevansAuthorUnsubmitted Done Inline Actions Good point- I'm leaning towards replacing it with `return (EISDIR)`. If the situation is volatile enough that we end up here after having checked back up in vn_io_fault, I'm not sure panicking has much utility from a debugging perspective and we're not not necessarily in a state that otherwise warrants it. kevans: Good point- I'm leaning towards replacing it with `return (EISDIR)`. If the situation is…
do {		do {
if (uio->uio_offset >= dep->de_FileSize)		if (uio->uio_offset >= dep->de_FileSize)
break;		break;
lbn = de_cluster(pmp, uio->uio_offset);		lbn = de_cluster(pmp, uio->uio_offset);
rablock = lbn + 1;		rablock = lbn + 1;
blsize = pmp->pm_bpcluster;		blsize = pmp->pm_bpcluster;
on = uio->uio_offset & pmp->pm_crbomask;		on = uio->uio_offset & pmp->pm_crbomask;
/*		if (de_cn2off(pmp, rablock) >= dep->de_FileSize) {
* If we are operating on a directory file then be sure to
* do i/o with the vnode for the filesystem instead of the
* vnode for the directory.
*/
if (isadir) {
/* convert cluster # to block # */
error = pcbmap(dep, lbn, &lbn, 0, &blsize);
if (error == E2BIG) {
error = EINVAL;
break;
} else if (error)
break;
error = bread(pmp->pm_devvp, lbn, blsize, NOCRED, &bp);
} else if (de_cn2off(pmp, rablock) >= dep->de_FileSize) {
error = bread(vp, lbn, blsize, NOCRED, &bp);		error = bread(vp, lbn, blsize, NOCRED, &bp);
} else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {		} else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
error = cluster_read(vp, dep->de_FileSize, lbn, blsize,		error = cluster_read(vp, dep->de_FileSize, lbn, blsize,
NOCRED, on + uio->uio_resid, seqcount, 0, &bp);		NOCRED, on + uio->uio_resid, seqcount, 0, &bp);
} else if (seqcount > 1) {		} else if (seqcount > 1) {
rasize = blsize;		rasize = blsize;
error = breadn(vp, lbn,		error = breadn(vp, lbn,
blsize, &rablock, &rasize, 1, NOCRED, &bp);		blsize, &rablock, &rasize, 1, NOCRED, &bp);
Show All 10 Lines	do {
if (diff < n)		if (diff < n)
n = diff;		n = diff;
diff = blsize - bp->b_resid;		diff = blsize - bp->b_resid;
if (diff < n)		if (diff < n)
n = diff;		n = diff;
error = vn_io_fault_uiomove(bp->b_data + on, (int) n, uio);		error = vn_io_fault_uiomove(bp->b_data + on, (int) n, uio);
brelse(bp);		brelse(bp);
} while (error == 0 && uio->uio_resid > 0 && n != 0);		} while (error == 0 && uio->uio_resid > 0 && n != 0);
if (!isadir && (error == 0 \|\| uio->uio_resid != orig_resid) &&		if ((error == 0 \|\| uio->uio_resid != orig_resid) &&
(vp->v_mount->mnt_flag & (MNT_NOATIME \| MNT_RDONLY)) == 0)		(vp->v_mount->mnt_flag & (MNT_NOATIME \| MNT_RDONLY)) == 0)
dep->de_flag \|= DE_ACCESS;		dep->de_flag \|= DE_ACCESS;
return (error);		return (error);
}		}

/*		/*
* Write data to a file or directory.		* Write data to a file or directory.
*/		*/
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