[ale] Permission hell question

[Dow Hurst]

So under Linux it is the options in fstab that really make the difference. 
The kernel overlays the mount point permissions with the mounted filesystem 
and allows the user to read and write at will.  Nice tests!  Did you specify 
the user or users option in the fstab?
Dow


Geoffrey wrote:
> Stephan Uphoff wrote:
> 
>> The permissions of the covered mount point usually only come into play
>> when accessing ".." from the root of the mounted fs.
>>
>> This is true for Unix and BSD ... but I have never looked at this part 
>> of the Linux sources.
>>
>> As a normal user try to
>>     cd /mnt/memstick  #OK
>>     pwd               #Fails unless cached by shell
>>     ls ..             #Should fail
>>
>> with /mnt/memstick permission set to 700 and user root.
> 
> 
> I don't agree, note the following, all done as a normal user:
> 
> /home/esoteric> cd /mnt/memstick
> ksh: cd: /mnt/memstick - Permission denied
> 
> rhws/home/esoteric> ls -l /mnt/memstick
> ls: /mnt/memstick: Permission denied
> 
> rhws/home/esoteric> ls -ld /mnt/memstick
> drwx------    2 root     root         4096 May 12 13:59 /mnt/memstick
> 
> rhws/home/esoteric> cd /mnt/memstick
> ksh: cd: /mnt/memstick - Permission denied
> 
> rhws/home/esoteric> mount /mnt/memstick
> 
> rhws/home/esoteric> cd /mnt/memstick
> 
> rhws/mnt/memstick> pwd
> /mnt/memstick
> 
> rhws/mnt/memstick> ls ..
> cdrom  floppy  jump  memstick
> 
> So, I don't believe your point above is valid.
> 
>> It is not really necessary to have matching permissions - but the 
>> wrong set
>> of permissions can cause interesting problems in a production 
>> environment.
> 
> 
> If the mount options are correct, the permissions on the mount point do 
> not matter.  I set the perms on /mnt/memstick to 000 as root:
> 
> d---------    2 root     root         4096 May 12 13:59 /mnt/memstick
> 
> I can still mount the partition as a normal user.  When I do, the perms 
> are:
> 
> drwxr-xr-x    3 esoteric users       16384 Dec 31  1969 /mnt/memstick
> 

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Dow Hurst                  Office: 770-499-3428            *
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