[PATCH] add child reaper to pid_namespace
Add a per pid_namespace child-reaper. This is needed so processes are reaped
within the same pid space and do not spill over to the parent pid space. Its
also needed so containers preserve existing semantic that pid == 1 would reap
orphaned children.
This is based on Eric Biederman's patch: http://lkml.org/lkml/2006/2/6/285
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/exec.c b/fs/exec.c
index 60433e22..12d8cd4 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -38,6 +38,7 @@
#include <linux/binfmts.h>
#include <linux/swap.h>
#include <linux/utsname.h>
+#include <linux/pid_namespace.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/proc_fs.h>
@@ -620,8 +621,8 @@
* Reparenting needs write_lock on tasklist_lock,
* so it is safe to do it under read_lock.
*/
- if (unlikely(tsk->group_leader == child_reaper))
- child_reaper = tsk;
+ if (unlikely(tsk->group_leader == child_reaper(tsk)))
+ tsk->nsproxy->pid_ns->child_reaper = tsk;
zap_other_threads(tsk);
read_unlock(&tasklist_lock);
diff --git a/include/linux/pid.h b/include/linux/pid.h
index 2c0007d..4dec047 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -35,8 +35,9 @@
*
* Holding a reference to struct pid solves both of these problems.
* It is small so holding a reference does not consume a lot of
- * resources, and since a new struct pid is allocated when the numeric
- * pid value is reused we don't mistakenly refer to new processes.
+ * resources, and since a new struct pid is allocated when the numeric pid
+ * value is reused (when pids wrap around) we don't mistakenly refer to new
+ * processes.
*/
struct pid
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 76e7c6b..d2a9d41 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -19,6 +19,7 @@
struct kref kref;
struct pidmap pidmap[PIDMAP_ENTRIES];
int last_pid;
+ struct task_struct *child_reaper;
};
extern struct pid_namespace init_pid_ns;
@@ -36,4 +37,9 @@
kref_put(&ns->kref, free_pid_ns);
}
+static inline struct task_struct *child_reaper(struct task_struct *tsk)
+{
+ return tsk->nsproxy->pid_ns->child_reaper;
+}
+
#endif /* _LINUX_PID_NS_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6fec1d4..f0317ed 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1400,7 +1400,6 @@
extern void daemonize(const char *, ...);
extern int allow_signal(int);
extern int disallow_signal(int);
-extern struct task_struct *child_reaper;
extern int do_execve(char *, char __user * __user *, char __user * __user *, struct pt_regs *);
extern long do_fork(unsigned long, unsigned long, struct pt_regs *, unsigned long, int __user *, int __user *);
diff --git a/init/main.c b/init/main.c
index 4cdcd06..036f97c 100644
--- a/init/main.c
+++ b/init/main.c
@@ -51,6 +51,7 @@
#include <linux/debug_locks.h>
#include <linux/lockdep.h>
#include <linux/utsrelease.h>
+#include <linux/pid_namespace.h>
#include <linux/compile.h>
#include <asm/io.h>
@@ -626,8 +627,6 @@
}
__setup("initcall_debug", initcall_debug_setup);
-struct task_struct *child_reaper = &init_task;
-
extern initcall_t __initcall_start[], __initcall_end[];
static void __init do_initcalls(void)
@@ -727,7 +726,7 @@
* assumptions about where in the task array this
* can be found.
*/
- child_reaper = current;
+ init_pid_ns.child_reaper = current;
cad_pid = task_pid(current);
diff --git a/kernel/exit.c b/kernel/exit.c
index 28d9fee..fd0e067 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -22,6 +22,7 @@
#include <linux/file.h>
#include <linux/binfmts.h>
#include <linux/nsproxy.h>
+#include <linux/pid_namespace.h>
#include <linux/ptrace.h>
#include <linux/profile.h>
#include <linux/mount.h>
@@ -48,7 +49,6 @@
#include <asm/mmu_context.h>
extern void sem_exit (void);
-extern struct task_struct *child_reaper;
static void exit_mm(struct task_struct * tsk);
@@ -260,7 +260,8 @@
}
/**
- * reparent_to_init - Reparent the calling kernel thread to the init task.
+ * reparent_to_init - Reparent the calling kernel thread to the init task
+ * of the pid space that the thread belongs to.
*
* If a kernel thread is launched as a result of a system call, or if
* it ever exits, it should generally reparent itself to init so that
@@ -278,8 +279,8 @@
ptrace_unlink(current);
/* Reparent to init */
remove_parent(current);
- current->parent = child_reaper;
- current->real_parent = child_reaper;
+ current->parent = child_reaper(current);
+ current->real_parent = child_reaper(current);
add_parent(current);
/* Set the exit signal to SIGCHLD so we signal init on exit */
@@ -662,7 +663,8 @@
* When we die, we re-parent all our children.
* Try to give them to another thread in our thread
* group, and if no such member exists, give it to
- * the global child reaper process (ie "init")
+ * the child reaper process (ie "init") in our pid
+ * space.
*/
static void
forget_original_parent(struct task_struct *father, struct list_head *to_release)
@@ -673,7 +675,7 @@
do {
reaper = next_thread(reaper);
if (reaper == father) {
- reaper = child_reaper;
+ reaper = child_reaper(father);
break;
}
} while (reaper->exit_state);
@@ -859,8 +861,13 @@
panic("Aiee, killing interrupt handler!");
if (unlikely(!tsk->pid))
panic("Attempted to kill the idle task!");
- if (unlikely(tsk == child_reaper))
- panic("Attempted to kill init!");
+ if (unlikely(tsk == child_reaper(tsk))) {
+ if (tsk->nsproxy->pid_ns != &init_pid_ns)
+ tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
+ else
+ panic("Attempted to kill init!");
+ }
+
if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
current->ptrace_message = code;
diff --git a/kernel/pid.c b/kernel/pid.c
index 1d9cc26..2efe9d8 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -65,7 +65,8 @@
.pidmap = {
[ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
},
- .last_pid = 0
+ .last_pid = 0,
+ .child_reaper = &init_task
};
/*
diff --git a/kernel/signal.c b/kernel/signal.c
index 9eac4db..1921ffd 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -24,6 +24,9 @@
#include <linux/signal.h>
#include <linux/capability.h>
#include <linux/freezer.h>
+#include <linux/pid_namespace.h>
+#include <linux/nsproxy.h>
+
#include <asm/param.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -1877,8 +1880,12 @@
if (sig_kernel_ignore(signr)) /* Default is nothing. */
continue;
- /* Init gets no signals it doesn't want. */
- if (current == child_reaper)
+ /*
+ * Init of a pid space gets no signals it doesn't want from
+ * within that pid space. It can of course get signals from
+ * its parent pid space.
+ */
+ if (current == child_reaper(current))
continue;
if (sig_kernel_stop(signr)) {