Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: [patch] unprivileged mounts update | Date | Wed, 25 Apr 2007 12:41:41 -0600 |
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"Serge E. Hallyn" <serge@hallyn.com> writes:
> Quoting Eric W. Biederman (ebiederm@xmission.com): >> >> Are there other permission checks that mount is doing that we >> care about. > > Not mount itself, but in looking up /share/fa/root/home/fa, > user fa doesn't have the rights to read /share, and by setting > fsuid to fa and dropping CAP_DAC_READ_SEARCH the mount action fails.
Got it.
I'm not certain this is actually a problem it may be a feature. But it does fly in the face of the general principle of just getting out of roots way so things can get done.
I think we can solve your basic problem by simply doing like: chdir(/share); mount(.); To simply avoid the permission problem.
The practical question is how much do we care.
> But the solution you outlined in your previous post would work around > this perfectly.
If we are not using usual permissions which user do we use current->uid? Or do we pass that user someplace?
>> > If it were really the equivalent then I could keep my capabilities :) >> > after changing it. >> >> We drop all capabilities after we change the euid. > > Not if we've done prctl(PR_SET_KEEPCAPS, 1)
Ah cap_clear doesn't do the obvious thing.
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