Re: [PATCH 0/16] Pid namespaces

[Pavel Emelianov <xemul@openvz.org>]

sukadev@us.ibm.com wrote:
> Pavel Emelianov [xemul@openvz.org] wrote:
> | This is "submition for inclusion" of hierarchical, not kconfig
> | configurable, zero overheaded ;) pid namespaces.
> | 
> | The overall idea is the following:
> | 
> | The namespace are organized as a tree - once a task is cloned
> | with CLONE_NEWPIDS (yes, I've also switched to it :) the new
> 
> Can you really clone() a pid namespace all by itself ?
> copy_namespaces() has the following:
> 
> 
>         if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWUSER)))
>                 return 0;
> 
> doesn't it mean you cannot create a pid namespace using clone() unless
> one of the above flags are also specified ?
> 
> unshare_nsproxy_namespaces() has the following correct check:
> 
>         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
>                                CLONE_NEWUSER | CLONE_NEWPIDS)))
>                 return 0;

I have lost a couple of hunks when I splitted the patch :(
That's the correct version, cap_set fix and the renamed CLONE_ flag.

--- ./include/linux/sched.h.fix	2007-07-06 11:09:33.000000000 +0400
+++ ./include/linux/sched.h	2007-07-10 13:48:19.000000000 +0400
@@ -26,7 +26,7 @@
 #define CLONE_NEWUTS		0x04000000	/* New utsname group? */
 #define CLONE_NEWIPC		0x08000000	/* New ipcs */
 #define CLONE_NEWUSER		0x10000000	/* New user namespace */
-#define CLONE_NEWPIDS		0x20000000	/* New pids */
+#define CLONE_NEWPID		0x20000000	/* New pids */
 
 /*
  * Scheduling policies
--- ./kernel/capability.c.fix	2007-07-06 11:09:33.000000000 +0400
+++ ./kernel/capability.c	2007-07-10 13:50:16.000000000 +0400
@@ -103,7 +103,7 @@ static inline int cap_set_pg(int pgrp_nr
 	int found = 0;
 	struct pid *pgrp;
 
-	pgrp = find_pid(pgrp_nr);
+	pgrp = find_pid_ns(pgrp_nr, current->nsproxy->pid_ns);
 	do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
 		target = g;
 		while_each_thread(g, target) {
--- ./kernel/fork.c.fix	2007-07-06 11:09:33.000000000 +0400
+++ ./kernel/fork.c	2007-07-10 13:48:13.000000000 +0400
@@ -1267,7 +1267,7 @@ static struct task_struct *copy_process(
 			__ptrace_link(p, current->parent);
 
 		if (thread_group_leader(p)) {
-			if (clone_flags & CLONE_NEWPIDS) {
+			if (clone_flags & CLONE_NEWPID) {
 				p->nsproxy->pid_ns->child_reaper = p;
 				p->signal->tty = NULL;
 				p->signal->pgrp = p->pid;
@@ -1434,7 +1434,7 @@ long do_fork(unsigned long clone_flags,
 		else
 			p->state = TASK_STOPPED;
 
-		nr = (clone_flags & CLONE_NEWPIDS) ?
+		nr = (clone_flags & CLONE_NEWPID) ?
 			pid_nr_ns(task_pid(p), current->nsproxy->pid_ns) :
 				pid_vnr(task_pid(p));
 
--- ./kernel/nsproxy.c.fix	2007-07-06 11:09:33.000000000 +0400
+++ ./kernel/nsproxy.c	2007-07-10 13:48:13.000000000 +0400
@@ -132,7 +132,8 @@ int copy_namespaces(unsigned long flags,
 
 	get_nsproxy(old_ns);
 
-	if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWUSER)))
+	if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
+					CLONE_NEWUSER | CLONE_NEWPID)))
 		return 0;
 
 	if (!capable(CAP_SYS_ADMIN)) {
@@ -184,7 +185,7 @@ int unshare_nsproxy_namespaces(unsigned 
 	int err = 0;
 
 	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
-			       CLONE_NEWUSER | CLONE_NEWPIDS)))
+			       CLONE_NEWUSER)))
 		return 0;
 
 	if (!capable(CAP_SYS_ADMIN))
--- ./kernel/pid.c.fix	2007-07-06 11:09:33.000000000 +0400
+++ ./kernel/pid.c	2007-07-10 13:48:19.000000000 +0400
@@ -523,7 +523,7 @@ struct pid_namespace *copy_pid_ns(unsign
 	BUG_ON(!old_ns);
 	get_pid_ns(old_ns);
 	new_ns = old_ns;
-	if (!(flags & CLONE_NEWPIDS))
+	if (!(flags & CLONE_NEWPID))
 		goto out;
 
 	new_ns = ERR_PTR(-EINVAL);