Subject: [PATCH] Cause the termination of the pspace leader to terminate all of it's children
From: Eric W. Biederman <ebiederman@lnxi.com>
Date: 1129919881 -0600

---

 include/linux/pspace.h |    9 +++++++++
 include/linux/sched.h  |    2 ++
 kernel/exit.c          |   33 ++++++++++++++++++++++++++++-----
 kernel/signal.c        |    5 ++---
 4 files changed, 41 insertions(+), 8 deletions(-)

f694494c1f4983b64ea82c5b2b9139e93ec3e994
diff --git a/include/linux/pspace.h b/include/linux/pspace.h
index 770fdf3..6a05210 100644
--- a/include/linux/pspace.h
+++ b/include/linux/pspace.h
@@ -75,5 +75,14 @@ static inline void exit_pspace(struct ta
 	tsk->pspace = NULL;
 }
 
+static inline int pspace_leader(struct task_struct *tsk)
+{
+	return tsk == tsk->pspace->child_reaper;
+}
+
+static inline int delay_pspace_leader(struct task_struct *tsk)
+{
+	return pspace_leader(tsk) && (tsk->pspace->nr_processes > 1);
+}
 
 #endif /* _LINUX_PSPACE_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 43f5afd..0b01c97 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1016,6 +1016,8 @@ extern int send_sig_info(int, struct sig
 extern int send_group_sig_info(int, struct siginfo *, struct task_struct *);
 extern int force_sigsegv(int, struct task_struct *);
 extern int force_sig_info(int, struct siginfo *, struct task_struct *);
+extern int __kill_pspace_info(int sig, struct siginfo *info, pid_t pspaceid);
+extern int kill_pspace_info(int sig, struct siginfo *info, pid_t pspaceid);
 extern int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp);
 extern int kill_pg_info(int, struct siginfo *, pid_t);
 extern int kill_proc_info(int, struct siginfo *, pid_t);
diff --git a/kernel/exit.c b/kernel/exit.c
index 82b39c0..aa349bf 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -562,9 +562,11 @@ static inline void reparent_thread(task_
 		 * anyway, so let go of it.
 		 */
 		p->ptrace = 0;
-		list_del_init(&p->sibling);
-		p->parent = p->real_parent;
-		list_add_tail(&p->sibling, &p->parent->children);
+		if (p->parent != p->real_parent) {
+			list_del_init(&p->sibling);
+			p->parent = p->real_parent;
+			list_add_tail(&p->sibling, &p->parent->children);
+		}
 
 		/* If we'd notified the old parent about this child's death,
 		 * also notify the new parent.
@@ -619,6 +621,7 @@ static inline void forget_original_paren
 		}
 	} while (reaper->exit_state);
 
+
 	/*
 	 * There are only two places where our children can be:
 	 *
@@ -710,7 +713,7 @@ static void exit_notify(struct task_stru
 
 	INIT_LIST_HEAD(&ptrace_dead);
 	forget_original_parent(tsk, &ptrace_dead);
-	BUG_ON(!list_empty(&tsk->children));
+	BUG_ON(!pspace_leader(tsk) && !list_empty(&tsk->children));
 	BUG_ON(!list_empty(&tsk->ptrace_children));
 
 	/*
@@ -733,6 +736,18 @@ static void exit_notify(struct task_stru
 		__kill_pg_info(SIGCONT, (void *)1, process_group(tsk));
 	}
 
+
+	/*
+	 * Check to see if we are the pspace leader.
+	 * If so it is nonsense for the pspace to continue so set
+	 * the SIGCHLD handler to SIG_IGN and kill everyone
+	 * else in the pspace.
+	 */
+	if (pspace_leader(tsk)) {
+		tsk->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_IGN;
+		__kill_pspace_info(SIGKILL, (void *)1, tsk->tgid);
+	}
+
 	/* Let father know we died 
 	 *
 	 * Thread signals are configurable, but you aren't going to use
@@ -804,7 +819,7 @@ fastcall NORET_TYPE void do_exit(long co
 		panic("Aiee, killing interrupt handler!");
 	if (unlikely(!tsk->pid))
 		panic("Attempted to kill the idle task!");
-	if (unlikely(tsk->pid == 1))
+	if (unlikely((tsk->pid == 1) && (tsk->pspace == &init_pspace)))
 		panic("Attempted to kill init!");
 	if (tsk->io_context)
 		exit_io_context();
@@ -979,6 +994,14 @@ static int eligible_child(pid_t pid, int
 	if (current->tgid != p->tgid && delay_group_leader(p))
 		return 2;
 
+
+	/*
+	 * Do not consider pspace leaders that are in
+	 * a non-empty pspace.
+	 */
+	if (delay_pspace_leader(p))
+		return 2;
+
 	if (security_task_wait(p))
 		return 0;
 
diff --git a/kernel/signal.c b/kernel/signal.c
index 6378175..6349ab5 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1165,7 +1165,7 @@ int __kill_pspace_info(int sig, struct s
 	max = pspace->offset + pspace->max;
 
 	for_each_process(p) {
-		if ((p->pid != current->pspace->offset + 1) && (p->tgid != current->tgid) &&
+		if ((p != current->pspace->child_reaper) && (p->tgid != current->tgid) &&
 			(p->pid > min) && (p->pid < max))
 		{
 			int err = group_send_sig_info(sig, info, p);
@@ -1177,8 +1177,7 @@ int __kill_pspace_info(int sig, struct s
 	return count ? retval : -ESRCH;
 }
 
-int
-kill_pspace_info(int sig, struct siginfo *info, pid_t pspaceid)
+int kill_pspace_info(int sig, struct siginfo *info, pid_t pspaceid)
 {
 	int retval;
 
-- 
1.0.GIT