Follow on patches for uid=/gid= behavior changes

From 200b7f2817aef7a33060b6bd6068b16175fa1379 Mon Sep 17 00:00:00 2001
From: Jeff Layton <[email protected]>
Date: Fri, 31 Jul 2009 09:34:26 -0400
Subject: [PATCH] cifs: add warning messages about change in default uid=/gid= behavior

Eventually, we'd like to change the meaning of the uid=/gid= options so
that they only specify file ownership when the server does not provide
that information. Changing this abruptly would be considered a regression,
so add a printk that warns about the upcoming change.

To silence the warning, admins can add the appropriate mount options to
clarify their intent when using these options.

Signed-off-by: Jeff Layton <[email protected]>
---
 fs/cifs/connect.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1f3345d..a375356 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1361,15 +1361,31 @@ cifs_parse_mount_options(char *options, const char *devname,
 	if (vol->UNCip == NULL)
 		vol->UNCip = &vol->UNC[2];
 
-	if (uid_specified)
+	if (uid_specified) {
 		vol->override_uid = override_uid;
-	else if (override_uid == 1)
+		if (override_uid == -1)
+			printk(KERN_WARNING "CIFS: the default behavior when "
+					    "uid= is specified will change in "
+					    "2.6.33 to only specify the owner "
+					    "when the server does not provide "
+					    "one. Add the forceuid or "
+					    "noforceuid options to silence "
+					    "this warning.\n");
+	} else if (override_uid == 1)
 		printk(KERN_NOTICE "CIFS: ignoring forceuid mount option "
 				   "specified with no uid= option.\n");
 
-	if (gid_specified)
+	if (gid_specified) {
 		vol->override_gid = override_gid;
-	else if (override_gid == 1)
+		if (override_gid == -1)
+			printk(KERN_WARNING "CIFS: the default behavior when "
+					    "gid= is specified will change in "
+					    "2.6.33 to only specify the group "
+					    "when the server does not provide "
+					    "one. Add the forcegid or "
+					    "noforcegid options to silence "
+					    "this warning.\n");
+	} else if (override_gid == 1)
 		printk(KERN_NOTICE "CIFS: ignoring forcegid mount option "
 				   "specified with no gid= option.\n");
 
-- 
1.6.0.6

From a4293786a63e7b7bea6666ba55d22577fed866ed Mon Sep 17 00:00:00 2001
From: Jeff Layton <[email protected]>
Date: Fri, 31 Jul 2009 09:51:53 -0400
Subject: [PATCH] cifs: update the README with information about uid=/forceuid/noforceuid

...and the corresponding gid options. Add some detail about how the
union of these options is intended to work.

Signed-off-by: Jeff Layton <[email protected]>
---
 fs/cifs/README |   55 +++++++++++++++++--------------------------------------
 1 files changed, 17 insertions(+), 38 deletions(-)

diff --git a/fs/cifs/README b/fs/cifs/README
index ad92921..a0223f5 100644
--- a/fs/cifs/README
+++ b/fs/cifs/README
@@ -262,44 +262,23 @@ A partial list of the supported mount options follows:
 		mount.	
   domain	Set the SMB/CIFS workgroup name prepended to the
 		username during CIFS session establishment
-  forceuid	Set the default uid for inodes based on the uid
-		passed in. For mounts to servers
-		which do support the CIFS Unix extensions, such as a
-		properly configured Samba server, the server provides
-		the uid, gid and mode so this parameter should  not be
-		specified unless the server and clients uid and gid
-		numbering differ.  If the server and client are in the
-		same domain (e.g. running winbind or nss_ldap) and
-		the server supports the Unix Extensions then the uid
-		and gid can be retrieved from the server (and uid
-		and gid would not have to be specifed on the mount. 
-		For servers which do not support the CIFS Unix
-		extensions, the default uid (and gid) returned on lookup
-		of existing files will be the uid (gid) of the person
-		who executed the mount (root, except when mount.cifs
-		is configured setuid for user mounts) unless the "uid=" 
-		(gid) mount option is specified.  For the uid (gid) of newly
-		created files and directories, ie files created since 
-		the last mount of the server share, the expected uid 
-		(gid) is cached as long as the inode remains in 
-		memory on the client.   Also note that permission
-		checks (authorization checks) on accesses to a file occur
-		at the server, but there are cases in which an administrator
-		may want to restrict at the client as well.  For those
-		servers which do not report a uid/gid owner
-		(such as Windows), permissions can also be checked at the
-		client, and a crude form of client side permission checking 
-		can be enabled by specifying file_mode and dir_mode on 
-		the client.  Note that the mount.cifs helper must be
-		at version 1.10 or higher to support specifying the uid
-		(or gid) in non-numeric form.
-  forcegid	(similar to above but for the groupid instead of uid)
-  uid		Set the default uid for inodes, and indicate to the
-		cifs kernel driver which local user mounted . If the server
-		supports the unix extensions the default uid is
-		not used to fill in the owner fields of inodes (files)
-		unless the "forceuid" parameter is specified.
-  gid		Set the default gid for inodes (similar to above).
+  uid		Set the ownership for all inodes, and indicate to the
+		cifs kernel driver which local user initiated the mount.
+		If the server supports the unix extensions, the owner provided
+		by the server will be overridden in favor of the one provided
+		by this option. To disable this behavior use "noforceuid".
+  noforceuid	Disable overriding ownership information from the server. With
+		this option, the value given in the uid= option will only be
+		used if the server does not provide one.
+  forceuid	Reverse a previously specified noforceuid option.
+  gid		Set the group ownership for all inodes. If the server supports
+		the unix extensions, the group provided by the server will be
+		overridden in favor of the one provided by this option. To
+		disable this behavior use "noforcegid".
+  noforcegid	Disable overriding group ownership information from the server.
+		With this option, the value given in the gid= option will only
+		be used if the server does not provide one.
+  forcegid	Reverse a previously specified noforcegid option.
   file_mode     If CIFS Unix extensions are not supported by the server
 		this overrides the default mode for file inodes.
   dir_mode      If CIFS Unix extensions are not supported by the server 
-- 
1.6.0.6

From a7708d4775a7f5789742baf832d25e4dfd45be59 Mon Sep 17 00:00:00 2001
From: Jeff Layton <[email protected]>
Date: Fri, 31 Jul 2009 09:19:32 -0400
Subject: [PATCH] manpage: update the mount.cifs manpage to reflect changes when uid= or gid= is specified

The change to not override ownership information when uid= is specified
was considered a regression so the older default behavior had to be
restored. Update the manpage to reflect the current situation
in-kernel.

Signed-off-by: Jeff Layton <[email protected]>
---
 docs-xml/manpages-3/mount.cifs.8.xml |   23 +++++++++++++----------
 1 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/docs-xml/manpages-3/mount.cifs.8.xml b/docs-xml/manpages-3/mount.cifs.8.xml
index 9383f3f..b8b7b50 100644
--- a/docs-xml/manpages-3/mount.cifs.8.xml
+++ b/docs-xml/manpages-3/mount.cifs.8.xml
@@ -128,8 +128,7 @@ credentials file properly.
 		<listitem>
 
 	<para>sets the uid that will own all files or directories on the
-mounted filesystem when the server does not provide ownership
-information. It may be specified as either a username or a numeric uid.
+mounted filesystem. It may be specified as either a username or a numeric uid.
 When not specified, the default is uid 0.  The mount.cifs helper must be
 at version 1.10 or higher to support specifying the uid in non-numeric
 form. See the section on FILE AND DIRECTORY OWNERSHIP AND PERMISSIONS below for more
@@ -152,8 +151,7 @@ be the value of the uid= option. See the section on FILE AND DIRECTORY OWNERSHIP
 	<listitem>
 
 		<para>sets the gid that will own all files or
-directories on the mounted filesystem when the server does not provide
-ownership information.  It may be specified as either a groupname or a
+directories on the mounted filesystem.  It may be specified as either a groupname or a
 numeric gid.  When not specified, the default is gid 0. The mount.cifs
 helper must be at version 1.10 or higher to support specifying the gid
 in non-numeric form. See the section on FILE AND DIRECTORY OWNERSHIP AND
@@ -534,7 +532,8 @@ uid= or gid= options are set, and will have permissions set to the
 default file_mode and dir_mode for the mount. Attempting to change these
 values via chmod/chown will return success but have no effect.</para>
 
-	<para>When the client and server negotiate unix extensions,
+	<para>When the client and server negotiate unix extensions
+and the uid= and gid= options are not specified,
 files and directories will be assigned the uid, gid, and mode provided
 by the server. Because CIFS mounts are generally single-user, and the
 same credentials are used no matter what user accesses the mount, newly
@@ -542,11 +541,15 @@ created files and directories will generally be given ownership
 corresponding to whatever credentials were used to mount the
 share.</para>
 
-	<para>If the uid's and gid's being used do not match on the
-client and server, the forceuid and forcegid options may be helpful.
-Note however, that there is no corresponding option to override the
-mode. Permissions assigned to a file when forceuid or forcegid are in
-effect may not reflect the the real permissions.</para>
+	<para>If the uid= or gid= options are provided then the
+ownership of all files and directories on the mount will be overridden.
+To prevent the client from clobbering file ownership information on
+these mounts, use the "noforceuid" and "noforcegid" options. Note that
+file modes are not overriden in this situation. Since the default
+behavior is to override ownership when the uid= and gid= options are in
+effect but file and directory modes are preserved, one should be cautious
+when using these options since the resulting permissions may grant
+unintended privileges.</para>
 
 	<para>When unix extensions are not negotiated, it's also
 possible to emulate them locally on the server using the "dynperm" mount
-- 
1.6.0.6