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_mode= 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_mode= 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 -- 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
