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

["Serge E. Hallyn" <serue@us.ibm.com>]

Quoting Serge E. Hallyn (serue@us.ibm.com):
> Quoting Serge E. Hallyn (serue@us.ibm.com):
> > Quoting Casey Schaufler (casey@schaufler-ca.com):
> > > 
> > > --- Jiri Slaby <jirislaby@gmail.com> 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.

No.  Seriously.  You're kidding me.

Patch attached  :(

Thanks for spotting this, Jiri.  I don't know where I introduced this
since I thought all my tests had passed...

thanks,
-serge

>From 70d5da610fdbd66a36886c01e27b7fb11d2de044 Mon Sep 17 00:00:00 2001
From: sergeh@us.ibm.com <hallyn@kernel.(none)>
Date: Wed, 28 Nov 2007 16:16:23 -0800
Subject: [PATCH 1/1] capabilities: correct logic at capset_check

Fix typo at capset_check introduced with capability bounding set
patch.

Signed-off-by: sergeh@us.ibm.com <hallyn@kernel.(none)>
---
 security/commoncap.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/security/commoncap.c b/security/commoncap.c
index c25ad09..503e958 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -119,7 +119,7 @@ int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
 		/* incapable of using this inheritable set */
 		return -EPERM;
 	}
-	if (!!cap_issubset(*inheritable,
+	if (!cap_issubset(*inheritable,
 			   cap_combine(target->cap_inheritable,
 				       current->cap_bset))) {
 		/* no new pI capabilities outside bounding set */
-- 
1.5.1

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