svn commit: r335868 - head/stand/common

[Allan Jude]

Author: allanjude
Date: Mon Jul  2 18:19:08 2018
New Revision: 335868
URL: https://svnweb.freebsd.org/changeset/base/335868

Log:
  stand/common/disk.c: Read partition table relative to the start of the disk
  
  If a disk is of an oddball size, like the 200mb + 512b used in rootgen.sh,
  when disk_open() is called on a GELI encrypted partition, attempts to read
  the partition table fail, as they pass through the decryption process which
  turns the already plaintext data into jibberish.
  
  When reading the partition table, always pass a slice and partition setting
  of -1, and an offset of 0. Setting the slice to -1 prevents a false
  positive when checking the slice against the cache of GELI encrypted
  slices.
  
  Reviewed by:	imp, ian
  Sponsored by:	Klara Systems
  Differential Revision:	https://reviews.freebsd.org/D15847

Modified:
  head/stand/common/disk.c

Modified: head/stand/common/disk.c
==============================================================================
--- head/stand/common/disk.c	Mon Jul  2 17:54:33 2018	(r335867)
+++ head/stand/common/disk.c	Mon Jul  2 18:19:08 2018	(r335868)
@@ -219,20 +219,13 @@ disk_ioctl(struct disk_devdesc *dev, u_long cmd, void 
 int
 disk_open(struct disk_devdesc *dev, uint64_t mediasize, u_int sectorsize)
 {
+	struct disk_devdesc partdev;
 	struct open_disk *od;
 	struct ptable *table;
 	struct ptable_entry part;
 	int rc, slice, partition;
 
 	rc = 0;
-	/*
-	 * While we are reading disk metadata, make sure we do it relative
-	 * to the start of the disk
-	 */
-	dev->d_offset = 0;
-	table = NULL;
-	slice = dev->d_slice;
-	partition = dev->d_partition;
 	od = (struct open_disk *)malloc(sizeof(struct open_disk));
 	if (od == NULL) {
 		DEBUG("no memory");
@@ -242,11 +235,24 @@ disk_open(struct disk_devdesc *dev, uint64_t mediasize
 	od->entrysize = 0;
 	od->mediasize = mediasize;
 	od->sectorsize = sectorsize;
+	/*
+	 * While we are reading disk metadata, make sure we do it relative
+	 * to the start of the disk
+	 */
+	memcpy(&partdev, dev, sizeof(partdev));
+	partdev.d_offset = 0;
+	partdev.d_slice = -1;
+	partdev.d_partition = -1;
+
+	table = NULL;
+	slice = dev->d_slice;
+	partition = dev->d_partition;
+
 	DEBUG("%s unit %d, slice %d, partition %d => %p",
 	    disk_fmtdev(dev), dev->dd.d_unit, dev->d_slice, dev->d_partition, od);
 
 	/* Determine disk layout. */
-	od->table = ptable_open(dev, mediasize / sectorsize, sectorsize,
+	od->table = ptable_open(&partdev, mediasize / sectorsize, sectorsize,
 	    ptblread);
 	if (od->table == NULL) {
 		DEBUG("Can't read partition table");