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. -Kees -- Kees Cook ChromeOS Security -- 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
