* Chris Wright ([email protected]) wrote:
> * Ingo Oeser ([email protected]) wrote:
> > Hi Chris,
> >
> > Andrew Morton wrote:
> > > Ingo Oeser <[email protected]> wrote:
> > > >
> > > > -int scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
> > > > -{
> > > > - struct task_struct *p = current;
> > > > - scm->creds = (struct ucred) {
> > > > - .uid = p->uid,
> > > > - .gid = p->gid,
> > > > - .pid = p->tgid
> > > > - };
> > > > - scm->fp = NULL;
> > > > - scm->sid = security_sk_sid(sock->sk, NULL, 0);
> > > > - scm->seq = 0;
> > > > - if (msg->msg_controllen <= 0)
> > > > - return 0;
> > > > - return __scm_send(sock, msg, scm);
> > > > -}
> > >
> > > It's worth noting that scm_send() will call security_sk_sid() even if
> > > (msg->msg_controllen <= 0).
> >
> > Chris, do you know if this is needed in this case?
>
> This whole thing is looking broken. I'm still trying to find the original
> patch which caused the series of broken patches on top.
OK, it starts here from Catherine's patch:
include/net/scm.h::scm_recv()
+ if (test_bit(SOCK_PASSSEC, &sock->flags)) {
+ err = security_sid_to_context(scm->sid, &scontext, &scontext_len);
+ if (!err)
+ put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, scontext_len, scontext);
+ }
Catherine, the security_sid_to_context() is a raw SELinux function which
crept into core code and should not have been there. The fallout fixes
included conditionally exporting security_sid_to_context, and finally
scm_send/recv unlining. The end result in -mm looks broken to me.
Specifically, it now does:
ucred->uid = tsk->uid;
ucred->gid = tsk->gid;
ucred->pid = tsk->tgid;
scm->fp = NULL;
scm->seq = 0;
if (msg->msg_controllen <= 0)
return 0;
scm->sid = security_sk_sid(sock->sk, NULL, 0);
The point of Catherine's original patch was to make sure there's always
a security identifier associated with AF_UNIX messages. So receiver
can always check it (same as having credentials even w/out sender
control message passing them). Now we will have garbage for sid.
thanks,
-chris
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