Re: named + capset = EPERM [Was: 2.6.24-rc3-mm2]

From: Serge E. Hallyn
Date: Wed Nov 28 2007 - 19:04:24 EST


Quoting Serge E. Hallyn (serue@xxxxxxxxxx):
> Quoting Casey Schaufler (casey@xxxxxxxxxxxxxxxx):
> >
> > --- Jiri Slaby <jirislaby@xxxxxxxxx> wrote:
> >
> > > On 11/28/2007 12:41 PM, Andrew Morton wrote:
> > > >
> > >
> > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24-rc3/2.6.24-rc3-mm2/
> > > [...]
> > > > +capabilities-introduce-per-process-capability-bounding-set.patch
> > >
> > > A regression against -mm1. This patch breaks bind (9.5.0-18.a7.fc8):
> > > capset(0x19980330, 0,
> > >
> > {CAP_DAC_READ_SEARCH|CAP_SETGID|CAP_SETUID|CAP_NET_BIND_SERVICE|CAP_SYS_CHROOT|CAP_SYS_RESOURCE,
> > >
> > CAP_DAC_READ_SEARCH|CAP_SETGID|CAP_SETUID|CAP_NET_BIND_SERVICE|CAP_SYS_CHROOT|CAP_SYS_RESOURCE,
> > > 0}) = -1 EPERM (Operation not permitted)
> > >
> > > $ grep SEC .config
> > > CONFIG_SECCOMP=y
> > > # CONFIG_NETWORK_SECMARK is not set
> > > CONFIG_RPCSEC_GSS_KRB5=m
> > > # CONFIG_RPCSEC_GSS_SPKM3 is not set
> > > # CONFIG_SECURITY is not set
> > > # CONFIG_SECURITY_FILE_CAPABILITIES is not set
> > >
> > > probably this hunk?:
> > > @@ -133,6 +119,12 @@ int cap_capset_check (struct task_struct
> > > /* incapable of using this inheritable set */
> > > return -EPERM;
> > > }
> > > + if (!!cap_issubset(*inheritable,
> > > + cap_combine(target->cap_inheritable,
> > > + current->cap_bset))) {
> > > + /* no new pI capabilities outside bounding set */
> > > + return -EPERM;
> > > + }
>
> That shouldn't be it, since you can't lower cap_bset since
> CONFIG_SECURITY_FILE_CAPABILITIES=n.

Hmm, but sure enough that appears to be it.

Still trying to figure out why.

thanks,
-serge
-
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