From d376fc4110ce10f8834cc1b4c5916de1912b21b6 Mon Sep 17 00:00:00 2001
From: phk <phk@FreeBSD.org>
Date: Fri, 20 Sep 2002 17:51:00 +0000
Subject: For reasons now lost in historical fog, the bounds_check_with_label()
 function were put in i386/i386/machdep.c from where it has been cut and
 pasted to other architectures with only minor corruption.

Disklabel is really a MI format in many ways, at least it certainly
is when you operate on struct disklabel.

Put bounds_check_with_label() back in subr_disklabel.c where it belongs.

Sponsored by:   DARPA & NAI Labs.
---
 sys/kern/subr_disklabel.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

(limited to 'sys/kern')

diff --git a/sys/kern/subr_disklabel.c b/sys/kern/subr_disklabel.c
index 000c1f0..9e27a96 100644
--- a/sys/kern/subr_disklabel.c
+++ b/sys/kern/subr_disklabel.c
@@ -216,3 +216,61 @@ done:
 	brelse(bp);
 	return (error);
 }
+
+/*
+ * Determine the size of the transfer, and make sure it is
+ * within the boundaries of the partition. Adjust transfer
+ * if needed, and signal errors or early completion.
+ */
+int
+bounds_check_with_label(struct bio *bp, struct disklabel *lp, int wlabel)
+{
+        struct partition *p = lp->d_partitions + dkpart(bp->bio_dev);
+        int labelsect = lp->d_partitions[0].p_offset;
+        int maxsz = p->p_size,
+                sz = (bp->bio_bcount + DEV_BSIZE - 1) >> DEV_BSHIFT;
+
+        /* overwriting disk label ? */
+        /* XXX should also protect bootstrap in first 8K */
+        if (bp->bio_blkno + p->p_offset <= LABELSECTOR + labelsect &&
+#if LABELSECTOR != 0
+            bp->bio_blkno + p->p_offset + sz > LABELSECTOR + labelsect &&
+#endif
+            (bp->bio_cmd == BIO_WRITE) && wlabel == 0) {
+                bp->bio_error = EROFS;
+                goto bad;
+        }
+
+#if     defined(DOSBBSECTOR) && defined(notyet)
+        /* overwriting master boot record? */
+        if (bp->bio_blkno + p->p_offset <= DOSBBSECTOR &&
+            (bp->bio_cmd == BIO_WRITE) && wlabel == 0) {
+                bp->bio_error = EROFS;
+                goto bad;
+        }
+#endif
+
+        /* beyond partition? */
+        if (bp->bio_blkno < 0 || bp->bio_blkno + sz > maxsz) {
+                /* if exactly at end of disk, return an EOF */
+                if (bp->bio_blkno == maxsz) {
+                        bp->bio_resid = bp->bio_bcount;
+                        return(0);
+                }
+                /* or truncate if part of it fits */
+                sz = maxsz - bp->bio_blkno;
+                if (sz <= 0) {
+                        bp->bio_error = EINVAL;
+                        goto bad;
+                }
+                bp->bio_bcount = sz << DEV_BSHIFT;
+        }
+
+        bp->bio_pblkno = bp->bio_blkno + p->p_offset;
+        return(1);
+
+bad:
+        bp->bio_flags |= BIO_ERROR;
+        return(-1);
+}
+
-- 
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