Re: Utilities don't take into account capabilities

[Linda Walsh <lkml@tlinx.org>]

Karel Zak wrote:
> The currently supported scenario is that you can remove suid from
>  mount(8) and replace it with cap_dac_override,cap_sys_admin+ep. Note
>  that in this case mount(8) still requires 'user' in fstab of course.
>   
---

   Is this planned, as the source I looked at still had uid==0 checks.
> 
>  The disadvantage is that mount(8) is not able to update for example
>  /etc/mtab (or /run/mount/utab), because cap_sys_admin is just subset of
>  the original suid privileges.

        This does point out an important issue -- should things like
cap_sys_admin also allow updating of run/mount/utab?  I would say "maybe":

        Updating /etc/mtab -- IF it is a separate file system object would
require write access to the file.  That could be handled with an ACL, or
CAP_DAC_OVERRIDE.  But the former "/run/mount/utab" -- isn't that a kernel
based file?  I.e. a pointer to /proc/self/mounts?  Either way -- if it is
a separate file, then it would be updated based on access and privilege,
but if it is a representation of kernel state, then it seems CAP_SYS_ADMIN
would be sufficient, no?


Linda