proc connector: reject unprivileged listener bumps
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 Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Acked-by: Matt Helsley <matthltc@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -313,6 +313,12 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg,
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(task_active_pid_ns(current) != &init_pid_ns))
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return;
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/* Can only change if privileged. */
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if (!capable(CAP_NET_ADMIN)) {
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err = EPERM;
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goto out;
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}
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mc_op = (enum proc_cn_mcast_op *)msg->data;
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switch (*mc_op) {
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case PROC_CN_MCAST_LISTEN:
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@ -325,6 +331,8 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg,
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err = EINVAL;
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break;
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}
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out:
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cn_proc_ack(err, msg->seq, msg->ack);
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}
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