oops, wrong subject. it should be :

	"user namespace : add the framework"

Sorry about that,

C.

Cedric Le Goater wrote:
> Basically, it will allow a process to unshare its user_struct table, resetting
> at the same time its own user_struct and all the associated accounting.
> 
> A new root user (uid == 0) is added to the user namespace upon creation.  Such
> root users have full privileges and it seems that theses privileges should be
> controlled through some means (process capabilities ?)
> 
> The unshare is not included in this patch.
> 
> Changes since [try #4]:
> 	- Updated get_user_ns and put_user_ns to accept NULL, and
> 	  get_user_ns to return the namespace.
> 
> Changes since [try #3]:
> 	- moved struct user_namespace to files user_namespace.{c,h}
> 
> Changes since [try #2]:
> 	- removed struct user_namespace* argument from find_user()
> 
> Changes since [try #1]:
> 	- removed struct user_namespace* argument from find_user()
> 	- added a root_user per user namespace
> 
> Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
> Signed-off-by: Andrew Morton <akpm@osdl.org>
> Acked-by: Pavel Emelianov <xemul@openvz.org>
> Cc: Herbert Poetzl <herbert@13thfloor.at>
> Cc: Kirill Korotaev <dev@sw.ru>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> ---
> 
>  include/linux/init_task.h      |    2 +
>  include/linux/nsproxy.h        |    1 
>  include/linux/sched.h          |    3 +-
>  include/linux/user_namespace.h |   57 +++++++++++++++++++++++++++++++++++++++++
>  init/Kconfig                   |    9 ++++++
>  kernel/Makefile                |    2 -
>  kernel/fork.c                  |    2 -
>  kernel/nsproxy.c               |    9 ++++++
>  kernel/sys.c                   |    5 ++-
>  kernel/user.c                  |   18 ++++++------
>  kernel/user_namespace.c        |   43 ++++++++++++++++++++++++++++++
>  11 files changed, 137 insertions(+), 14 deletions(-)
> 
> Index: 2.6.22-rc4-mm2/include/linux/init_task.h
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/include/linux/init_task.h
> +++ 2.6.22-rc4-mm2/include/linux/init_task.h
> @@ -8,6 +8,7 @@
>  #include <linux/lockdep.h>
>  #include <linux/ipc.h>
>  #include <linux/pid_namespace.h>
> +#include <linux/user_namespace.h>
> 
>  #define INIT_FDTABLE \
>  {							\
> @@ -78,6 +79,7 @@ extern struct nsproxy init_nsproxy;
>  	.uts_ns		= &init_uts_ns,					\
>  	.mnt_ns		= NULL,						\
>  	INIT_IPC_NS(ipc_ns)						\
> +	.user_ns	= &init_user_ns,				\
>  }
> 
>  #define INIT_SIGHAND(sighand) {						\
> Index: 2.6.22-rc4-mm2/include/linux/nsproxy.h
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/include/linux/nsproxy.h
> +++ 2.6.22-rc4-mm2/include/linux/nsproxy.h
> @@ -28,6 +28,7 @@ struct nsproxy {
>  	struct ipc_namespace *ipc_ns;
>  	struct mnt_namespace *mnt_ns;
>  	struct pid_namespace *pid_ns;
> +	struct user_namespace *user_ns;
>  };
>  extern struct nsproxy init_nsproxy;
> 
> Index: 2.6.22-rc4-mm2/include/linux/sched.h
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/include/linux/sched.h
> +++ 2.6.22-rc4-mm2/include/linux/sched.h
> @@ -268,6 +268,7 @@ extern signed long schedule_timeout_unin
>  asmlinkage void schedule(void);
> 
>  struct nsproxy;
> +struct user_namespace;
> 
>  /* Maximum number of active map areas.. This is a random (large) number */
>  #define DEFAULT_MAX_MAP_COUNT	65536
> @@ -1378,7 +1379,7 @@ extern struct task_struct *find_task_by_
>  extern void __set_special_pids(pid_t session, pid_t pgrp);
> 
>  /* per-UID process charging. */
> -extern struct user_struct * alloc_uid(uid_t);
> +extern struct user_struct * alloc_uid(struct user_namespace *, uid_t);
>  static inline struct user_struct *get_uid(struct user_struct *u)
>  {
>  	atomic_inc(&u->__count);
> Index: 2.6.22-rc4-mm2/include/linux/user_namespace.h
> ===================================================================
> --- /dev/null
> +++ 2.6.22-rc4-mm2/include/linux/user_namespace.h
> @@ -0,0 +1,57 @@
> +#ifndef _LINUX_USER_NAMESPACE_H
> +#define _LINUX_USER_NAMESPACE_H
> +
> +#include <linux/kref.h>
> +#include <linux/nsproxy.h>
> +#include <linux/sched.h>
> +
> +#define UIDHASH_BITS	(CONFIG_BASE_SMALL ? 3 : 8)
> +#define UIDHASH_SZ	(1 << UIDHASH_BITS)
> +
> +struct user_namespace {
> +	struct kref		kref;
> +	struct list_head	uidhash_table[UIDHASH_SZ];
> +	struct user_struct	*root_user;
> +};
> +
> +extern struct user_namespace init_user_ns;
> +
> +#ifdef CONFIG_USER_NS
> +
> +static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
> +{
> +	if (ns)
> +		kref_get(&ns->kref);
> +	return ns;
> +}
> +
> +extern struct user_namespace *copy_user_ns(int flags,
> +					   struct user_namespace *old_ns);
> +extern void free_user_ns(struct kref *kref);
> +
> +static inline void put_user_ns(struct user_namespace *ns)
> +{
> +	if (ns)
> +		kref_put(&ns->kref, free_user_ns);
> +}
> +
> +#else
> +
> +static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
> +{
> +	return &init_user_ns;
> +}
> +
> +static inline struct user_namespace *copy_user_ns(int flags,
> +						  struct user_namespace *old_ns)
> +{
> +	return NULL;
> +}
> +
> +static inline void put_user_ns(struct user_namespace *ns)
> +{
> +}
> +
> +#endif
> +
> +#endif /* _LINUX_USER_H */
> Index: 2.6.22-rc4-mm2/init/Kconfig
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/init/Kconfig
> +++ 2.6.22-rc4-mm2/init/Kconfig
> @@ -231,6 +231,15 @@ config TASK_IO_ACCOUNTING
> 
>  	  Say N if unsure.
> 
> +config USER_NS
> +	bool "User Namespaces (EXPERIMENTAL)"
> +	default n
> +	depends on EXPERIMENTAL
> +	help
> +	  Support user namespaces.  This allows containers, i.e.
> +	  vservers, to use user namespaces to provide different
> +	  user info for different servers.  If unsure, say N.
> +
>  config AUDIT
>  	bool "Auditing support"
>  	depends on NET
> Index: 2.6.22-rc4-mm2/kernel/Makefile
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/kernel/Makefile
> +++ 2.6.22-rc4-mm2/kernel/Makefile
> @@ -4,7 +4,7 @@
> 
>  obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
>  	    exit.o itimer.o time.o softirq.o resource.o \
> -	    sysctl.o capability.o ptrace.o timer.o user.o \
> +	    sysctl.o capability.o ptrace.o timer.o user.o user_namespace.o \
>  	    signal.o sys.o kmod.o workqueue.o pid.o \
>  	    rcupdate.o extable.o params.o posix-timers.o \
>  	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
> Index: 2.6.22-rc4-mm2/kernel/fork.c
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/kernel/fork.c
> +++ 2.6.22-rc4-mm2/kernel/fork.c
> @@ -1004,7 +1004,7 @@ static struct task_struct *copy_process(
>  	if (atomic_read(&p->user->processes) >=
>  			p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
>  		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
> -				p->user != &root_user)
> +		    p->user != current->nsproxy->user_ns->root_user)
>  			goto bad_fork_free;
>  	}
> 
> Index: 2.6.22-rc4-mm2/kernel/nsproxy.c
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/kernel/nsproxy.c
> +++ 2.6.22-rc4-mm2/kernel/nsproxy.c
> @@ -79,8 +79,15 @@ static struct nsproxy *create_new_namesp
>  	if (IS_ERR(new_nsp->pid_ns))
>  		goto out_pid;
> 
> +	new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns);
> +	if (IS_ERR(new_nsp->user_ns))
> +		goto out_user;
> +
>  	return new_nsp;
> 
> +out_user:
> +	if (new_nsp->pid_ns)
> +		put_pid_ns(new_nsp->pid_ns);
>  out_pid:
>  	if (new_nsp->ipc_ns)
>  		put_ipc_ns(new_nsp->ipc_ns);
> @@ -140,6 +147,8 @@ void free_nsproxy(struct nsproxy *ns)
>  		put_ipc_ns(ns->ipc_ns);
>  	if (ns->pid_ns)
>  		put_pid_ns(ns->pid_ns);
> +	if (ns->user_ns)
> +		put_user_ns(ns->user_ns);
>  	kfree(ns);
>  }
> 
> Index: 2.6.22-rc4-mm2/kernel/sys.c
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/kernel/sys.c
> +++ 2.6.22-rc4-mm2/kernel/sys.c
> @@ -35,6 +35,7 @@
>  #include <linux/compat.h>
>  #include <linux/syscalls.h>
>  #include <linux/kprobes.h>
> +#include <linux/user_namespace.h>
> 
>  #include <asm/uaccess.h>
>  #include <asm/io.h>
> @@ -1078,13 +1079,13 @@ static int set_user(uid_t new_ruid, int 
>  {
>  	struct user_struct *new_user;
> 
> -	new_user = alloc_uid(new_ruid);
> +	new_user = alloc_uid(current->nsproxy->user_ns, new_ruid);
>  	if (!new_user)
>  		return -EAGAIN;
> 
>  	if (atomic_read(&new_user->processes) >=
>  				current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
> -			new_user != &root_user) {
> +			new_user != current->nsproxy->user_ns->root_user) {
>  		free_uid(new_user);
>  		return -EAGAIN;
>  	}
> I