[PATCH] smbd: Fix snapshot query on shares with DFS enabled

[Jeremy Allison]

On Mon, Aug 15, 2016 at 04:25:10PM -0700, Christof Schmitt wrote:
> On Fri, Aug 12, 2016 at 04:51:35PM -0700, Jeremy Allison wrote:
> > On Fri, Aug 12, 2016 at 03:59:27PM -0700, Christof Schmitt wrote:
> > > From 3a33435fc3d61605c75ed3f3b87612fbe729b553 Mon Sep 17 00:00:00 2001
> > > From: Christof Schmitt <cs at samba.org>
> > > Date: Fri, 12 Aug 2016 14:59:07 -0700
> > > Subject: [PATCH] smbd: Fix snapshot query on shares with DFS enabled
> > > 
> > > When DFS is enabled (host msdfs = yes and msdfs root = yes), then SMB
> > > clients send create requests in the format \hostname\service\path.
> > > Putting the GMT tag as first element breaks the DFS parsing and results
> > > in OBJECT_NOT_FOUND for snapshotted files.  Fix this by appending the
> > > GMT tag to the end of the path.
> > 
> > Great catch ! Pushed with additional comment:
> > 
> > BUG: https://bugzilla.samba.org/show_bug.cgi?id=12150
> > 
> > as we're going to need this backported.
> 
> I just came across one more thing: The test is on a system with the
> shadowcopy2 module enabled. While the patches fixes the problem for
> directories, there seems to be an issue when a SMB client is explicitly
> asking for older versions of a file. It looks like shadowcopy leaves a
> trailing slash from the GMT tag removal:
> 
> (test is a file, not  a directory)
> 
> [2016/08/15 16:12:36.178799, 10, pid=13125, effective(12000500, 12000513), real(12000500, 0)] ../source3/modules/vfs_shadow_copy2.c:245(shadow_copy2_strip_snapshot)
>   ../source3/modules/vfs_shadow_copy2.c:245: enter path 'test/@GMT-2016.08.12-19.56.11'
> [2016/08/15 16:12:36.178814, 10, pid=13125, effective(12000500, 12000513), real(12000500, 0)] ../source3/modules/vfs_shadow_copy2.c:462(shadow_copy2_do_convert)
>  converting 'test/'
> [2016/08/15 16:12:36.178837, 10, pid=13125, effective(12000500, 12000513), real(12000500, 0)] ../source3/modules/vfs_shadow_copy2.c:604(shadow_copy2_do_convert)
>  Trying[snapdirseverywhere] /fs1/smbexport1/test/.snapshots/@GMT-2016.08.12-19.56.11/: -1 (Not a directory)
> [2016/08/15 16:12:36.178860, 10, pid=13125, effective(12000500, 12000513), real(12000500, 0)] ../source3/modules/vfs_shadow_copy2.c:604(shadow_copy2_do_convert)
>  Trying[snapdirseverywhere] /fs1/smbexport1/.snapshots/@GMT-2016.08.12-19.56.11/test/: -1 (No such file or directory)
> [2016/08/15 16:12:36.178886, 10, pid=13125, effective(12000500, 12000513), real(12000500, 0)] ../source3/modules/vfs_shadow_copy2.c:604(shadow_copy2_do_convert)
>  Trying[snapdirseverywhere] /fs1/.snapshots/@GMT-2016.08.12-19.56.11/smbexport1/test/: -1 (Not a directory)
> 
> I will try to take a closer look tomorrow, maybe that can be easily
> handled in the shadowcopy2 module. The backport should probably wait
> until this is resolved

I think this should fix it - can you test ?

I'll work on a regression test now.

Thanks,

Jeremy.
-------------- next part --------------
From 3b54af0e18172e4b3aae294df0edfe97e572a480 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra at samba.org>
Date: Tue, 16 Aug 2016 09:41:43 -0700
Subject: [PATCH 1/2] s3: vfs: shadow_copy2: Re-use an existing variable
 already set to the right value (p - name).

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12150

Signed-off-by: Jeremy Allison <jra at samba.org>
---
 source3/modules/vfs_shadow_copy2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/source3/modules/vfs_shadow_copy2.c b/source3/modules/vfs_shadow_copy2.c
index bda934e..b1aae1e 100644
--- a/source3/modules/vfs_shadow_copy2.c
+++ b/source3/modules/vfs_shadow_copy2.c
@@ -486,7 +486,8 @@ static bool shadow_copy2_strip_snapshot(TALLOC_CTX *mem_ctx,
 		 * with a path prefix.
 		 */
 		if (pstripped != NULL) {
-			stripped = talloc_strndup(mem_ctx, name, p - name);
+			stripped = talloc_strndup(mem_ctx, name,
+					len_before_gmt);
 			if (stripped == NULL) {
 				return false;
 			}
-- 
2.8.0.rc3.226.g39d4020


From 3b14aa977d069479ceadd912ca4c109887849f20 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra at samba.org>
Date: Tue, 16 Aug 2016 09:43:37 -0700
Subject: [PATCH 2/2] s3: vfs: shadow_copy2. Remove any trailing slash when
 stripping @GMT-YYYY... from the end of a path.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12150

Signed-off-by: Jeremy Allison <jra at samba.org>
---
 source3/modules/vfs_shadow_copy2.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/source3/modules/vfs_shadow_copy2.c b/source3/modules/vfs_shadow_copy2.c
index b1aae1e..4ac16d3 100644
--- a/source3/modules/vfs_shadow_copy2.c
+++ b/source3/modules/vfs_shadow_copy2.c
@@ -486,6 +486,13 @@ static bool shadow_copy2_strip_snapshot(TALLOC_CTX *mem_ctx,
 		 * with a path prefix.
 		 */
 		if (pstripped != NULL) {
+			if (len_before_gmt > 0) {
+				/*
+				 * There is a slash before
+				 * the @GMT-. Remove it.
+				 */
+				len_before_gmt -= 1;
+			}
 			stripped = talloc_strndup(mem_ctx, name,
 					len_before_gmt);
 			if (stripped == NULL) {
-- 
2.8.0.rc3.226.g39d4020