Re: [PATCH -mm 1/2] user namespace : add unshare

From: Cedric Le Goater
Date: Fri Jun 08 2007 - 11:23:15 EST

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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@xxxxxxxxxx>
> Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
> Acked-by: Pavel Emelianov <xemul@xxxxxxxxxx>
> Cc: Herbert Poetzl <herbert@xxxxxxxxxxxx>
> Cc: Kirill Korotaev <dev@xxxxx>
> Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> ---
>
> 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;
> }
> Index: 2.6.22-rc4-mm2/kernel/user.c
> ===================================================================
> --- 2.6.22-rc4-mm2.orig/kernel/user.c
> +++ 2.6.22-rc4-mm2/kernel/user.c
> @@ -14,20 +14,19 @@
> #include <linux/bitops.h>
> #include <linux/key.h>
> #include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/user_namespace.h>
>
> /*
> * UID task count cache, to get fast user lookup in "alloc_uid"
> * when changing user ID's (ie setuid() and friends).
> */
>
> -#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 8)
> -#define UIDHASH_SZ (1 << UIDHASH_BITS)
> #define UIDHASH_MASK (UIDHASH_SZ - 1)
> #define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
> -#define uidhashentry(uid) (uidhash_table + __uidhashfn((uid)))
> +#define uidhashentry(ns, uid) ((ns)->uidhash_table + __uidhashfn((uid)))
>
> static struct kmem_cache *uid_cachep;
> -static struct list_head uidhash_table[UIDHASH_SZ];
>
> /*
> * The uidhash_lock is mostly taken from process context, but it is
> @@ -94,9 +93,10 @@ struct user_struct *find_user(uid_t uid)
> {
> struct user_struct *ret;
> unsigned long flags;
> + struct user_namespace *ns = current->nsproxy->user_ns;
>
> spin_lock_irqsave(&uidhash_lock, flags);
> - ret = uid_hash_find(uid, uidhashentry(uid));
> + ret = uid_hash_find(uid, uidhashentry(ns, uid));
> spin_unlock_irqrestore(&uidhash_lock, flags);
> return ret;
> }
> @@ -120,9 +120,9 @@ void free_uid(struct user_struct *up)
> }
> }
>
> -struct user_struct * alloc_uid(uid_t uid)
> +struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
> {
> - struct list_head *hashent = uidhashentry(uid);
> + struct list_head *hashent = uidhashentry(ns, uid);
> struct user_struct *up;
>
> spin_lock_irq(&uidhash_lock);
> @@ -211,11 +211,11 @@ static int __init uid_cache_init(void)
> 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
>
> for(n = 0; n < UIDHASH_SZ; ++n)
> - INIT_LIST_HEAD(uidhash_table + n);
> + INIT_LIST_HEAD(init_user_ns.uidhash_table + n);
>
> /* Insert the root user immediately (init already runs as root) */
> spin_lock_irq(&uidhash_lock);
> - uid_hash_insert(&root_user, uidhashentry(0));
> + uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0));
> spin_unlock_irq(&uidhash_lock);
>
> return 0;
> Index: 2.6.22-rc4-mm2/kernel/user_namespace.c
> ===================================================================
> --- /dev/null
> +++ 2.6.22-rc4-mm2/kernel/user_namespace.c
> @@ -0,0 +1,43 @@
> +/*
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation, version 2 of the
> + * License.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/version.h>
> +#include <linux/nsproxy.h>
> +#include <linux/user_namespace.h>
> +
> +struct user_namespace init_user_ns = {
> + .kref = {
> + .refcount = ATOMIC_INIT(2),
> + },
> + .root_user = &root_user,
> +};
> +
> +EXPORT_SYMBOL_GPL(init_user_ns);
> +
> +#ifdef CONFIG_USER_NS
> +
> +struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
> +{
> + struct user_namespace *new_ns;
> +
> + BUG_ON(!old_ns);
> + get_user_ns(old_ns);
> +
> + new_ns = old_ns;
> + return new_ns;
> +}
> +
> +void free_user_ns(struct kref *kref)
> +{
> + struct user_namespace *ns;
> +
> + ns = container_of(kref, struct user_namespace, kref);
> + kfree(ns);
> +}
> +
> +#endif /* CONFIG_USER_NS */
> -
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Next message: Alan Cox: "Re: spurious completions during NCQ?"
Previous message: Paul Fulghum: "Re: [Bug 8473] New: Oops: 0010 [1] SMP"
In reply to: Cedric Le Goater: "[PATCH -mm 1/2] user namespace : add unshare"
Next in thread: Andrew Morton: "Re: [PATCH -mm 1/2] user namespace : add unshare"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]