On Fri, 2016-07-29 at 14:11 +0100, Sachin Prabhu wrote: > On Fri, 2016-06-10 at 17:16 +0200, Aurélien Aptel wrote: > > > > On Thu, 9 Jun 2016 21:27:34 +0200 Marcus Hoffmann > > <marcus.hoffmann@xxxxxxxxxxxx> wrote: > > > > > > > > > Hey Aurélien, > > > with your script I can reproduce the bug locally now. > > Good. > > > > > > > > > > > I can mount the share (which is on a Windows 8.1 vm) with a > > > Windows > > > 7 > > > PC with the restricted user account. (Even in hard mode.) > > > I can mount the share from Linux-cifs using the admin user but > > > not > > > the > > > restricted user. > > I've moved some things around. All of the prefix path components > > are > > now checked for accessibility in cifs_do_mount(). This is more > > robust and it lets us set the CIFS_MOUNT_USE_PREFIX_PATH flag > > earlier. > > > > I've updated the cifs_root_iget() to use the prefix path when > > necessary > > which should take care of the last case (hard mode). > > > > Please test my latest patch (attached). > > > > > > > > > > > (I noticed though that no user has access to the file in the > > > shared > > > dir. But this doesn't really matter for the test.) > > Indeed. > > > > Hello, > > Sorry for the late reply but this has to be a NACK from me. > > We need to check for CIFS_MOUNT_USE_PREFIX_PATH > and if set, check cifs_sb->prepath for both old and new > in cifs_match_super(). > > Else we have the following bug: > > Consider 2 different mounts on a server where root access is limited. > I > used the reproducer for this case but simply created a separate > folder > in the root directory to which the user has access. I then attempt to > mount the 2 separate folders in 2 different locations. > > # mount -t cifs -vvv -o username=wintest1,password=xxx //vm140- > 52/test2/sub/dir /mnt > # mount -t cifs -vvv -o username=wintest1,password=xxx //vm140- > 52/test2/sub2/ /mnt2 > > # grep mnt /proc/mounts > //vm140-52/test2/sub/dir /mnt cifs > rw,relatime,vers=1.0,cache=strict,username=wintest1,domain=ENG1,uid=0 > ,n > oforceuid,gid=0,noforcegid,addr=192.168.140.52,file_mode=0755,dir_mod > e= > 0755,nounix,serverino,mapposix,rsize=61440,wsize=16580,echo_interval= > 60 > ,actimeo=1 0 0 > //vm140-52/test2/sub2/ /mnt2 cifs > rw,relatime,vers=1.0,cache=strict,username=wintest1,domain=ENG1,uid=0 > ,n > oforceuid,gid=0,noforcegid,addr=192.168.140.52,file_mode=0755,dir_mod > e= > 0755,nounix,serverino,mapposix,rsize=61440,wsize=16580,echo_interval= > 60 > ,actimeo=1 0 0 > > but since we do not compare the prepath, we end up with the same > share > mounted at both mount points. This is the share mounted first. > > To confirm. > > # date >/mnt/test > # cat /mnt/test /mnt2/test > Fri 29 Jul 14:05:19 BST 2016 > Fri 29 Jul 14:05:19 BST 2016 > > Steve, > > Can you recall the earlier patch or should I write a fix for this? > > Sachin Prabhu This bug in the patch was masked by another issue which was fixed by the patch cifs: unbreak TCP session reuse by Rabin Vincent which has been posted to go into upstream at the same time as this patch. Sachin Prabhu -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
