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Re: [PATCH 1/6] user namespace : add the framework [message #13940 is a reply to message #13756] Fri, 08 June 2007 08:35 Go to previous messageGo to previous message
Pavel Emelianov is currently offline  Pavel Emelianov
Messages: 1149
Registered: September 2006
Senior Member
Serge E. Hallyn wrote:
>>From nobody Mon Sep 17 00:00:00 2001
> From: Cedric Le Goater <clg@fr.ibm.com>
> Date: Thu, 5 Apr 2007 12:51:51 -0400
> Subject: [PATCH 1/6] user namespace : add the framework
>
> Add the user namespace struct and framework
>
> 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>
> Cc: Herbert Poetzl <herbert@13thfloor.at>
> Cc: Kirill Korotaev <dev@sw.ru>
> Cc: "Eric W. Biederman" <ebiederm@xmission.com>
> Signed-off-by: Andrew Morton <akpm@osdl.org>
>
> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>

Acked-by: Pavel Emelianov <xemul@openvz.org>

Yup. This patch is good :)

> ---
>
> 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 | 10 +++++++
> kernel/sys.c | 5 ++--
> kernel/user.c | 18 ++++++-------
> kernel/user_namespace.c | 43 ++++++++++++++++++++++++++++++
> 11 files changed, 138 insertions(+), 14 deletions(-)
> create mode 100644 include/linux/user_namespace.h
> create mode 100644 kernel/user_namespace.c
>
> cfeebe74a11622089791ecb14070f4d620f55535
> diff --git a/include/linux/init_task.h b/include/linux/init_task.h
> index cca7bb1..1fdc46c 100644
> --- a/include/linux/init_task.h
> +++ b/include/linux/init_task.h
> @@ -8,6 +8,7 @@ #include <linux/utsname.h>
> #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 @@ #define INIT_NSPROXY(nsproxy) { \
> .uts_ns = &init_uts_ns, \
> .mnt_ns = NULL, \
> INIT_IPC_NS(ipc_ns) \
> + .user_ns = &init_user_ns, \
> }
>
> #define INIT_SIGHAND(sighand) { \
> diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
> index 616a710..36e84e5 100644
> --- a/include/linux/nsproxy.h
> +++ b/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;
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 8016ec8..259d0a5 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -263,6 +263,7 @@ 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
> @@ -1311,7 +1312,7 @@ 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);
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> new file mode 100644
> index 0000000..c2debd8
> --- /dev/null
> +++ b/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 0;
> +}
> +
> +static inline void put_user_ns(struct user_namespace *ns)
> +{
> +}
> +
> +#endif
> +
> +#endif /* _LINUX_USER_H */
> diff --git a/init/Kconfig b/init/Kconfig
> index 99b0b32..0bbf957 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -229,6 +229,15 @@ 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
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 6101981..b5cef19 100644
> --- a/kernel/Makefile
> +++ b/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 timer.o user.o \
> + sysctl.o capability.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 \
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 6ebd35b..c20137e 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -999,7 +999,7 @@ #endif
> 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;
> }
>
> diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
> index 3f3b7ad..1ea8a73 100644
> --- a/kernel/nsproxy.c
> +++ b/kernel/nsproxy.c
> @@ -83,8 +83,15 @@ 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);
> @@ -144,6 +151,9 @@ 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);
> +
> kmem_cache_free(nsproxy_cachep, ns);
> }
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 7d79146..bb37fcb 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -34,6 +34,7 @@ #include <linux/task_io_accounting_ops.h
> #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>
> @@ -1077,13 +1078,13 @@ 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_u ...

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