Re: 2.2.12 bug in mount(2) or what?

James Manning (jmm@raleigh.ibm.com)
Wed, 24 Nov 1999 08:31:52 -0500

[ Wednesday, November 24, 1999 ] Tigran Aivazian wrote:
> Have a look at this, please:
>
> # grep cdrom /etc/fstab
> /dev/cdrom /mnt/cdrom iso9660 noauto,ro,exec,user,dev 0 0
> # mount /mnt/cdrom
> # grep cdrom /etc/mtab
> /dev/cdrom /mnt/cdrom iso9660 ro,noexec,nosuid 0 0
> # id
> uid=0(root) gid=0(root)
> groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel)
> # uname -a
> Linux einstein.london.sco.com 2.2.12 #1 Wed Sep 29 08:15:49 BST 1999 i686
> unknown
>
> now, why is "exec" turned into "noexec"? Since I am root, I therefore have
> all capabilities (ignoring all those modern "capabilities" stuff until I
> understand them) and so mount should do what it is told. What is wrong
> here?

Actually, this is a documented feature :)

I had the same problem before finally finding the critical section of
the mount(8) man page:

user Allow an ordinary user to mount the file
system. This option implies the options
noexec, nosuid, and nodev (unless overridden
by subsequent options, as in the option line
user,exec,dev,suid).

Hence, in your fstab simply move the "exec" after the "user" option
and it will become active as the options are processed sequentially
and the user option is enforcing noexec.

(Took me a while to figure out what was wrong while trying to install
a package from CD :)

James

-- 
Miscellaneous Engineer --- IBM Netfinity Performance Development


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