| Message ID | 20130226073225.GA15489@www.outflux.net |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
Hi On Mon, Feb 25, 2013 at 11:32:25PM -0800, Kees Cook (keescook@chromium.org) wrote: > While PROC_CN_MCAST_LISTEN/IGNORE is entirely advisory, it was possible > for an unprivileged user to turn off notifications for all listeners by > sending PROC_CN_MCAST_IGNORE. Instead, require the same privileges as > required for a multicast bind. Sounds resonable. Not sure whether this is a candidate for stable release, but otherwise Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
On Mon, Feb 25, 2013 at 11:32:25PM -0800, Kees Cook wrote: > While PROC_CN_MCAST_LISTEN/IGNORE is entirely advisory, it was possible > for an unprivileged user to turn off notifications for all listeners by > sending PROC_CN_MCAST_IGNORE. Instead, require the same privileges as > required for a multicast bind. > > Signed-off-by: Kees Cook <keescook@chromium.org> > Cc: Evgeniy Polyakov <zbr@ioremap.net> > Cc: Matt Helsley <matthltc@us.ibm.com> > Cc: stable@vger.kernel.org > --- > drivers/connector/cn_proc.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c > index fce2000..1110478 100644 > --- a/drivers/connector/cn_proc.c > +++ b/drivers/connector/cn_proc.c > @@ -313,6 +313,12 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg, > (task_active_pid_ns(current) != &init_pid_ns)) > return; > > + /* Can only change if privileged. */ I think this comment doesn't tell us anything above and beyond the what capability check already tells us. I think you could improve it by noting that since the connector is multicast and not namespace-safe it's not yet appropriate to use ns_capable() here. Acked-by: Matt Helsley <matthltc@us.ibm.com> > + if (!capable(CAP_NET_ADMIN)) { > + err = EPERM; > + goto out; > + } -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Matt Helsley <matthltc@linux.vnet.ibm.com> Date: Tue, 26 Feb 2013 09:24:41 -0800 > On Mon, Feb 25, 2013 at 11:32:25PM -0800, Kees Cook wrote: >> While PROC_CN_MCAST_LISTEN/IGNORE is entirely advisory, it was possible >> for an unprivileged user to turn off notifications for all listeners by >> sending PROC_CN_MCAST_IGNORE. Instead, require the same privileges as >> required for a multicast bind. >> >> Signed-off-by: Kees Cook <keescook@chromium.org> >> Cc: Evgeniy Polyakov <zbr@ioremap.net> >> Cc: Matt Helsley <matthltc@us.ibm.com> >> Cc: stable@vger.kernel.org >> --- >> drivers/connector/cn_proc.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c >> index fce2000..1110478 100644 >> --- a/drivers/connector/cn_proc.c >> +++ b/drivers/connector/cn_proc.c >> @@ -313,6 +313,12 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg, >> (task_active_pid_ns(current) != &init_pid_ns)) >> return; >> >> + /* Can only change if privileged. */ > > I think this comment doesn't tell us anything above and beyond the > what capability check already tells us. I think you could improve it > by noting that since the connector is multicast and not namespace-safe > it's not yet appropriate to use ns_capable() here. > > Acked-by: Matt Helsley <matthltc@us.ibm.com> Applied. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c index fce2000..1110478 100644 --- a/drivers/connector/cn_proc.c +++ b/drivers/connector/cn_proc.c @@ -313,6 +313,12 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg, (task_active_pid_ns(current) != &init_pid_ns)) return; + /* Can only change if privileged. */ + if (!capable(CAP_NET_ADMIN)) { + err = EPERM; + goto out; + } + mc_op = (enum proc_cn_mcast_op *)msg->data; switch (*mc_op) { case PROC_CN_MCAST_LISTEN: @@ -325,6 +331,8 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg, err = EINVAL; break; } + +out: cn_proc_ack(err, msg->seq, msg->ack); }
While PROC_CN_MCAST_LISTEN/IGNORE is entirely advisory, it was possible for an unprivileged user to turn off notifications for all listeners by sending PROC_CN_MCAST_IGNORE. Instead, require the same privileges as required for a multicast bind. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Evgeniy Polyakov <zbr@ioremap.net> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: stable@vger.kernel.org --- drivers/connector/cn_proc.c | 8 ++++++++ 1 file changed, 8 insertions(+)