Introduce PS_NOBROADCASTKILL a process flag that excludes processes from

receiving broadcast signals (kill -1). The flag can be set via a new
sysctl KERN_PROC_NOBROADCASTKILL. This will be used by iscsid to survive
the mass killing by init(8) when terminating multi-user operations.
With and OK guenther@

4 files changed, 58 insertions, 7 deletions

diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 970507f28b6..88a8865d1a9 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sig.c,v 1.172 2014/07/13 15:46:21 uebayasi Exp $	*/
+/*	$OpenBSD: kern_sig.c,v 1.173 2014/07/13 16:41:21 claudio Exp $	*/
 /*	$NetBSD: kern_sig.c,v 1.54 1996/04/22 01:38:32 christos Exp $	*/
 
 /*
@@ -629,7 +629,8 @@ killpg1(struct proc *cp, int signum, int pgid, int all)
 		 * broadcast
 		 */
 		LIST_FOREACH(pr, &allprocess, ps_list) {
-			if (pr->ps_pid <= 1 || pr->ps_flags & PS_SYSTEM ||
+			if (pr->ps_pid <= 1 ||
+			    pr->ps_flags & (PS_SYSTEM | PS_NOBROADCASTKILL) ||
 			    pr == cp->p_p || !cansignal(cp, pr, signum))
 				continue;
 			nfound++;
diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index c0a9d02cc43..d89199df16a 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sysctl.c,v 1.257 2014/07/13 15:29:04 tedu Exp $	*/
+/*	$OpenBSD: kern_sysctl.c,v 1.258 2014/07/13 16:41:21 claudio Exp $	*/
 /*	$NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $	*/
 
 /*-
@@ -116,6 +116,8 @@ extern void nmbclust_update(void);
 int sysctl_diskinit(int, struct proc *);
 int sysctl_proc_args(int *, u_int, void *, size_t *, struct proc *);
 int sysctl_proc_cwd(int *, u_int, void *, size_t *, struct proc *);
+int sysctl_proc_nobroadcastkill(int *, u_int, void *, size_t, void *, size_t *,
+	struct proc *);
 int sysctl_intrcnt(int *, u_int, void *, size_t *);
 int sysctl_sensors(int *, u_int, void *, size_t *, void *, size_t);
 int sysctl_emul(int *, u_int, void *, size_t *, void *, size_t);
@@ -284,6 +286,7 @@ kern_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 		case KERN_POOL:
 		case KERN_PROC_ARGS:
 		case KERN_PROC_CWD:
+		case KERN_PROC_NOBROADCASTKILL:
 		case KERN_SYSVIPC_INFO:
 		case KERN_SEMINFO:
 		case KERN_SHMINFO:
@@ -372,6 +375,9 @@ kern_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 	case KERN_PROC_CWD:
 		return (sysctl_proc_cwd(name + 1, namelen - 1, oldp, oldlenp,
 		     p));
+	case KERN_PROC_NOBROADCASTKILL:
+		return (sysctl_proc_nobroadcastkill(name + 1, namelen - 1,
+		     newp, newlen, oldp, oldlenp, p));
 	case KERN_FILE:
 		return (sysctl_file(name + 1, namelen - 1, oldp, oldlenp, p));
 #endif
@@ -1820,6 +1826,47 @@ sysctl_proc_cwd(int *name, u_int namelen, void *oldp, size_t *oldlenp,
 
 	return (error);
 }
+
+int
+sysctl_proc_nobroadcastkill(int *name, u_int namelen, void *newp, size_t newlen,
+    void *oldp, size_t *oldlenp, struct proc *cp)
+{
+	struct process *findpr;
+	pid_t pid;
+	int error, flag;
+
+	if (namelen > 1)
+		return (ENOTDIR);
+	if (namelen < 1)
+		return (EINVAL);
+
+	pid = name[0];
+	if ((findpr = prfind(pid)) == NULL)
+		return (ESRCH);
+
+	/* Either system process or exiting/zombie */
+	if (findpr->ps_flags & (PS_SYSTEM | PS_EXITING))
+		return (EINVAL);
+
+	/* Only root can change PS_NOBROADCASTKILL */
+	if (newp != 0 && (error = suser(cp, 0)) != 0)
+		return (error);
+
+	/* get the PS_NOBROADCASTKILL flag */
+	flag = findpr->ps_flags & PS_NOBROADCASTKILL ? 1 : 0;
+
+	error = sysctl_int(oldp, oldlenp, newp, newlen, &flag);
+	if (error == 0 && newp) {
+		if (flag)
+			atomic_setbits_int(&findpr->ps_flags,
+			    PS_NOBROADCASTKILL);
+		else
+			atomic_clearbits_int(&findpr->ps_flags,
+			    PS_NOBROADCASTKILL);
+	}
+
+	return (error);
+}
 #endif
 
 /*
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index d7c3224701e..6f25f2c0e52 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: proc.h,v 1.189 2014/07/12 21:21:19 matthew Exp $	*/
+/*	$OpenBSD: proc.h,v 1.190 2014/07/13 16:41:21 claudio Exp $	*/
 /*	$NetBSD: proc.h,v 1.44 1996/04/22 01:23:21 christos Exp $	*/
 
 /*-
@@ -247,12 +247,13 @@ struct process {
 #define	PS_SYSTEM	0x00010000	/* No sigs, stats or swapping. */
 #define	PS_EMBRYO	0x00020000	/* New process, not yet fledged */
 #define	PS_ZOMBIE	0x00040000	/* Dead and ready to be waited for */
+#define	PS_NOBROADCASTKILL 0x00080000	/* Process excluded from kill -1. */
 
 #define	PS_BITS \
     ("\20\01CONTROLT\02EXEC\03INEXEC\04EXITING\05SUGID" \
      "\06SUGIDEXEC\07PPWAIT\010ISPWAIT\011PROFIL\012TRACED" \
      "\013WAITED\014COREDUMP\015SINGLEEXIT\016SINGLEUNWIND" \
-     "\017NOZOMBIE\020STOPPED\021SYSTEM\022EMBRYO\023ZOMBIE")
+     "\017NOZOMBIE\020STOPPED\021SYSTEM\022EMBRYO\023ZOMBIE\024NOBROADCASTKILL")
 
 
 struct proc {
diff --git a/sys/sys/sysctl.h b/sys/sys/sysctl.h
index b9e38a95369..889e997e0f3 100644
--- a/sys/sys/sysctl.h
+++ b/sys/sys/sysctl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sysctl.h,v 1.147 2014/07/08 17:19:26 deraadt Exp $	*/
+/*	$OpenBSD: sysctl.h,v 1.148 2014/07/13 16:41:22 claudio Exp $	*/
 /*	$NetBSD: sysctl.h,v 1.16 1996/04/09 20:55:36 cgd Exp $	*/
 
 /*
@@ -179,7 +179,8 @@ struct ctlname {
 #define	KERN_NETLIVELOCKS	76	/* int: number of network livelocks */
 #define	KERN_POOL_DEBUG		77	/* int: enable pool_debug */
 #define	KERN_PROC_CWD		78      /* node: proc cwd */
-#define	KERN_MAXID		79	/* number of valid kern ids */
+#define	KERN_PROC_NOBROADCASTKILL 79	/* node: proc no broadcast kill */
+#define	KERN_MAXID		80	/* number of valid kern ids */
 
 #define	CTL_KERN_NAMES { \
 	{ 0, 0 }, \
@@ -261,6 +262,7 @@ struct ctlname {
 	{ "netlivelocks", CTLTYPE_INT }, \
 	{ "pool_debug", CTLTYPE_INT }, \
 	{ "proc_cwd", CTLTYPE_NODE }, \
+	{ "proc_nobroadcastkill", CTLTYPE_NODE }, \
 }
 
 /*