From 4ae1507f6d266d0cc3dd36e474d83aad70fec9e4 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Sun, 24 May 2009 18:45:15 -0400 Subject: [PATCH] cifs: make overriding of ownership conditional on new mount options We have a bit of a problem with the uid= option. The basic issue is that it means too many things and has too many side-effects. It's possible to allow an unprivileged user to mount a filesystem if the user owns the mountpoint, /bin/mount is setuid root, and the mount is set up in /etc/fstab with the "user" option. When doing this though, /bin/mount automatically adds the "uid=" and "gid=" options to the share. This is fortunate since the correct uid= option is needed in order to tell the upcall what user's credcache to use when generating the SPNEGO blob. On a mount without unix extensions this is fine -- you generally will want the files to be owned by the "owner" of the mount. The problem comes in on a mount with unix extensions. With those enabled, the uid/gid options cause the ownership of files to be overriden even though the server is sending along the ownership info. This means that it's not possible to have a mount by an unprivileged user that shows the server's file ownership info. The result is also inode permissions that have no reflection at all on the server. You simply cannot separate ownership from the mode in this fashion. This behavior also makes MultiuserMount option less usable. Once you pass in the uid= option for a mount, then you can't use unix ownership info and allow someone to share the mount. While I'm not thrilled with it, the only solution I can see is to stop making uid=/gid= force the overriding of ownership on mounts, and to add new mount options that turn this behavior on. Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/connect.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 74b5a87e919..10151f8d849 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -1096,17 +1096,17 @@ cifs_parse_mount_options(char *options, const char *devname, return 1; } } else if (strnicmp(data, "uid", 3) == 0) { - if (value && *value) { + if (value && *value) vol->linux_uid = simple_strtoul(value, &value, 0); + } else if (strnicmp(data, "forceuid", 8) == 0) { vol->override_uid = 1; - } } else if (strnicmp(data, "gid", 3) == 0) { - if (value && *value) { + if (value && *value) vol->linux_gid = simple_strtoul(value, &value, 0); + } else if (strnicmp(data, "forcegid", 8) == 0) { vol->override_gid = 1; - } } else if (strnicmp(data, "file_mode", 4) == 0) { if (value && *value) { vol->file_mode =