Chris Wright <[email protected]> wrote:
>
> * 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.
Yes. So we're OK up the uninlining, right?
> 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.
This answers the question I've been asking all and sundry for a week, thanks ;)
So:
- scm-fold-__scm_send-into-scm_send.patch is OK
- scm_send-speedup.patch is wrong
- Catherine's patch introduces a possibly-significant performance
problem: we're now calling the expensive-on-SELinux security_sk_sid()
more frequently than we used to.
- That "initialise scm->creds via a temporary struct" trick still
generates bad code.
I actually have enough to be going on with here - I'll drop it all.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
