Cryptoapi on 2.4.17 (2 patches)

[Zygo Blaxell <umsfalfb@xxxxxxxxxxxxxxxxxxxxx>]

I have two patches, one for cryptoAPI (current CVS) and one for the
Linux kernel (2.4.17).  

The cryptoapi patch fixes a silly symbol name bug.  The
patch for the Linux kernel changes the default lo_iv_mode to
LO_IV_MODE_SECTOR--otherwise, the patch is just a straightforward port
of the patch in cryptoapi/doc in cryptoavi CVS.

I noticed that there doesn't seem to be a way to set lo_iv_mode from
user-space, not even with a module or kernel command-line parameter.
Is this just one of those features that isn't implemented yet, or did
I miss something?

The patches seem to work:  I can swap on an rc6 encrypted partition
using the patches, and I can create an ext2 filesystem on an rc6 loopback
file, copy some data to it, unmount, losetup -d, losetup -e, mount it
again, and _still access the data afterwards_.  Whee!

This still doesn't completely work for encrypted swap because somebody
(who shall remain nameless, but whose name rhymes with socks) seems to
have "lost" the kreclaimd kernel thread.  I thought I would try to get 
someone else to look at this before tackling that problem...

? tests/.deps
? tests/Makefile
? tests/Makefile.in
Index: api/cryptoloop.c
===================================================================
RCS file: /cvsroot/cryptoapi/cryptoapi/api/cryptoloop.c,v
retrieving revision 1.4
diff -u -r1.4 cryptoloop.c
--- api/cryptoloop.c	2001/12/14 23:38:49	1.4
+++ api/cryptoloop.c	2001/12/26 21:30:57
@@ -44,7 +44,7 @@
 # error you need at least kernel 2.4.3 -- unless you know exacty what you are doing
 #endif
 
-#if !defined(LOOP_IV_SECTOR_SIZE)
+#if !defined(LO_IV_SECTOR_SIZE)
 # error you need to to patch your loop.c driver
 #endif
 
@@ -85,10 +85,10 @@
   struct cipher_context *cx;
 
   /* encryption breaks for non sector aligned offsets */
-  if (info->lo_offset % LOOP_IV_SECTOR_SIZE) 
+  if (info->lo_offset % LO_IV_SECTOR_SIZE) 
     goto out;
 
-  lx->blocksize = LOOP_IV_SECTOR_SIZE;
+  lx->blocksize = LO_IV_SECTOR_SIZE;
   lx->debug = 0;
 
   strncpy(cipher, info->lo_name, LO_NAME_SIZE);
@@ -163,7 +163,7 @@
     out = raw_buf;
   }
 
-  IV /= blocksize / LOOP_IV_SECTOR_SIZE;
+  IV /= blocksize / LO_IV_SECTOR_SIZE;
 
 #if defined(CRYPTOLOOP_DEBUG)
   if (lx->debug)
@@ -203,7 +203,7 @@
   switch (cmd) {
   case CRYPTOLOOP_SET_BLKSIZE:
     printk (KERN_DEBUG "cryptoloop: switch to blocksize %d requested\n", *arg_int);
-    if (*arg_int >= 0 && (*arg_int % LOOP_IV_SECTOR_SIZE == 0))
+    if (*arg_int >= 0 && (*arg_int % LO_IV_SECTOR_SIZE == 0))
       {
         lx->blocksize = *arg_int;
         err = 0;

--- /home/zblaxell/linux/p3-laptop/kernel-source-2.4.17-zb-p3-laptop-zb2001122605/drivers/block/loop.c	Fri Dec 21 12:41:53 2001
+++ drivers/block/loop.c	Wed Dec 26 13:59:05 2001
@@ -36,6 +36,9 @@
  * Al Viro too.
  * Jens Axboe <axboe@xxxxxxx>, Nov 2000
  *
+ * Fixed and made IV calculation customizable by lo_iv_mode
+ * Herbert Valerio Riedel <hvr@xxxxxxx>, Apr 2001
+ *
  * Still To Fix:
  * - Advisory locking is ignored here. 
  * - Should use an own CAP_* category instead of CAP_SYS_ADMIN 
@@ -168,6 +171,43 @@
 					lo->lo_device);
 }
 
+static inline int loop_get_bs(struct loop_device *lo)
+{
+	int bs = 0;
+
+	if (blksize_size[MAJOR(lo->lo_device)])
+		bs = blksize_size[MAJOR(lo->lo_device)][MINOR(lo->lo_device)];
+	if (!bs)
+		bs = BLOCK_SIZE;	
+
+	return bs;
+}
+
+static inline unsigned long loop_get_iv(struct loop_device *lo,
+					unsigned long sector)
+{
+	unsigned long offset, IV;
+	int bs;
+
+	switch (lo->lo_iv_mode) {
+		case LO_IV_MODE_SECTOR:
+			IV = sector + (lo->lo_offset >> LO_IV_SECTOR_BITS);
+			break;
+
+		default:
+			printk (KERN_WARNING "loop: unexpected lo_iv_mode\n");
+		case LO_IV_MODE_DEFAULT:
+			bs = loop_get_bs(lo);
+			IV = sector / (bs >> 9) + lo->lo_offset / bs;
+			offset = ((sector % (bs >> 9)) << 9) + lo->lo_offset % bs;
+			if (offset >= bs)
+				IV++;
+			break;
+	}
+
+	return IV;
+}
+
 static int lo_send(struct loop_device *lo, struct buffer_head *bh, int bsize,
 		   loff_t pos)
 {
@@ -186,7 +226,7 @@
 	len = bh->b_size;
 	data = bh->b_data;
 	while (len > 0) {
-		int IV = index * (PAGE_CACHE_SIZE/bsize) + offset/bsize;
+                unsigned long IV = loop_get_iv(lo, (pos - lo->lo_offset) >> LO_IV_SECTOR_BITS);
 		int transfer_result;
 
 		size = PAGE_CACHE_SIZE - offset;
@@ -244,7 +284,10 @@
 	unsigned long count = desc->count;
 	struct lo_read_data *p = (struct lo_read_data*)desc->buf;
 	struct loop_device *lo = p->lo;
-	int IV = page->index * (PAGE_CACHE_SIZE/p->bsize) + offset/p->bsize;
+	unsigned long IV = loop_get_iv(lo,
+		((page->index <<  (PAGE_CACHE_SHIFT - LO_IV_SECTOR_BITS))
+		+ (offset >> LO_IV_SECTOR_BITS)
+		- (lo->lo_offset >> LO_IV_SECTOR_BITS)));
 
 	if (size > count)
 		size = count;
@@ -284,32 +327,6 @@
 	return desc.error;
 }
 
-static inline int loop_get_bs(struct loop_device *lo)
-{
-	int bs = 0;
-
-	if (blksize_size[MAJOR(lo->lo_device)])
-		bs = blksize_size[MAJOR(lo->lo_device)][MINOR(lo->lo_device)];
-	if (!bs)
-		bs = BLOCK_SIZE;	
-
-	return bs;
-}
-
-static inline unsigned long loop_get_iv(struct loop_device *lo,
-					unsigned long sector)
-{
-	int bs = loop_get_bs(lo);
-	unsigned long offset, IV;
-
-	IV = sector / (bs >> 9) + lo->lo_offset / bs;
-	offset = ((sector % (bs >> 9)) << 9) + lo->lo_offset % bs;
-	if (offset >= bs)
-		IV++;
-
-	return IV;
-}
-
 static int do_bh_filebacked(struct loop_device *lo, struct buffer_head *bh, int rw)
 {
 	loff_t pos;
@@ -677,6 +694,7 @@
 	lo->lo_backing_file = file;
 	lo->transfer = NULL;
 	lo->ioctl = NULL;
+	lo->lo_iv_mode = LO_IV_MODE_SECTOR;
 	figure_loop_size(lo);
 	lo->old_gfp_mask = inode->i_mapping->gfp_mask;
 	inode->i_mapping->gfp_mask = GFP_NOIO;

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