From 10b66aa0a9a308f429504b22f03f8cb96d91e809 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sun, 8 Apr 2001 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2001-04-08

---
 port/devproc.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/port/devproc.c b/port/devproc.c
index 2b6ab6874276514b8623b3cd4ce59f2f78f3859f..fd27afd8a6b2497706dcadf11211d829e4c2bc47 100644
--- a/port/devproc.c
+++ b/port/devproc.c
@@ -159,6 +159,24 @@ procstat(Chan *c, char *db)
 	devstat(c, db, 0, 0, procgen);
 }
 
+/*
+ *  none can't read or write state on other
+ *  processes.  This is to contain access of
+ *  servers running as none should they be
+ *  subverted by, for example, a stack attack.
+ */
+static void
+nonone(Proc *p)
+{
+	if(p == up)
+		return;
+	if(strcmp(up->user, "none") != 0)
+		return;
+	if(iseve())
+		return;
+	error(Eperm);
+}
+
 static Chan*
 procopen(Chan *c, int omode)
 {
@@ -209,6 +227,7 @@ procopen(Chan *c, int omode)
 	case Qwait:
 	case Qregs:
 	case Qfpregs:
+		nonone(p);
 		break;
 
 	case Qns:
@@ -218,6 +237,7 @@ procopen(Chan *c, int omode)
 		break;
 
 	case Qnotepg:
+		nonone(p);
 		pg = p->pgrp;
 		if(pg == nil)
 			error(Eprocdied);
@@ -258,6 +278,7 @@ procwstat(Chan *c, char *db)
 		error(Eperm);
 
 	p = proctab(SLOT(c->qid));
+	nonone(p);
 	if(waserror()){
 		qunlock(&p->debug);
 		nexterror();