On 01/13/2012 07:09 AM, Kees Cook wrote: > On Thu, Jan 12, 2012 at 10:02 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >> On Thu, Jan 12, 2012 at 9:58 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: >>> On Thu, Jan 12, 2012 at 6:12 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >>>> With this set, a lot of dangerous operations (chroot, unshare, etc) >>>> become a lot less dangerous because there is no possibility of >>>> subverting privileged binaries. >>>> >>>> This patch completely breaks apparmor. Someone who understands (and >>>> uses) apparmor should fix it or at least give me a hint. >>>> >>>> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx> >>>> [....] >>>> diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c >>>> index c1e18ba..7f480b7 100644 >>>> --- a/security/apparmor/domain.c >>>> +++ b/security/apparmor/domain.c >>>> @@ -360,6 +360,9 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm) >>>> if (bprm->cred_prepared) >>>> return 0; >>>> >>>> + /* XXX: someone who understands apparmor needs to fix this. */ >>>> + BUG_ON(bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS); >>>> + >>>> cxt = bprm->cred->security; >>>> BUG_ON(!cxt); >>>> >>> >>> Since apparmor_bprm_set_creds() calls cap_bprm_set_creds() already[1], >>> I think AppArmor needs no changes at all, but John will know better. >>> :) >> >> I think that AppArmor determines what a program is allowed to do by >> looking at the path of the executable. We don't want newly-executed >> programs to gain permissions because they're a different executable >> when we're in no_new_privs mode, so (if I'm right) something different >> needs to happen. > > I'll have to go look more closely. I thought cap_bprm_set_creds() was > already evaluating the new privs and blocking any gained privs with > the changes you were making. > We do want to do something more. A first pass at it would be to allow execs that inherit the current context, and we will also want to reject apparmor's equiv of setcon, and setexeccon, at the interface. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
