Serge E. Hallyn wrote:
>>From nobody Mon Sep 17 00:00:00 2001
> From: Serge E. Hallyn <[EMAIL PROTECTED]>
> Date: Thu, 5 Apr 2007 13:00:47 -0400
> Subject: [PATCH 2/6] user namespace : add unshare
>
> Changelog: Fix !CONFIG_USER_NS clone with CLONE_NEWUSER so it returns -EINVAL
> rather than 0, so that userspace knows they didn't get a new user
> namespace.
>
> Cc: Serge E. Hallyn <[EMAIL PROTECTED]>
> Cc: Herbert Poetzl <[EMAIL PROTECTED]>
> Cc: Kirill Korotaev <[EMAIL PROTECTED]>
> Cc: "Eric W. Biederman" <[EMAIL PROTECTED]>
> Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
>
> Signed-off-by: Serge E. Hallyn <[EMAIL PROTECTED]>
Acked-by: Pavel Emelianov <[EMAIL PROTECTED]>
> ---
>
> include/linux/sched.h | 1 +
> include/linux/user_namespace.h | 5 +++-
> kernel/fork.c | 2 +-
> kernel/nsproxy.c | 10 +++++++--
> kernel/user_namespace.c | 46
> +++++++++++++++++++++++++++++++++++++++-
> 5 files changed, 59 insertions(+), 5 deletions(-)
>
> 4ddd1e8f0539d843e998ea26d0c6c9cb751cbf3e
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 259d0a5..ad19efa 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -26,6 +26,7 @@ #define CLONE_CHILD_SETTID 0x01000000 /*
> #define CLONE_STOPPED 0x02000000 /* Start in stopped
> state */
> #define CLONE_NEWUTS 0x04000000 /* New utsname group? */
> #define CLONE_NEWIPC 0x08000000 /* New ipcs */
> +#define CLONE_NEWUSER 0x10000000 /* New user namespace */
>
> /*
> * Scheduling policies
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index c2debd8..9044456 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -45,7 +45,10 @@ static inline struct user_namespace *get
> static inline struct user_namespace *copy_user_ns(int flags,
> struct user_namespace *old_ns)
> {
> - return 0;
> + if (flags & CLONE_NEWUSER)
> + return ERR_PTR(-EINVAL);
> +
> + return NULL;
> }
>
> static inline void put_user_ns(struct user_namespace *ns)
> diff --git a/kernel/fork.c b/kernel/fork.c
> index c20137e..123bc93 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1581,7 +1581,7 @@ asmlinkage long sys_unshare(unsigned lon
> err = -EINVAL;
> if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
> CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
> - CLONE_NEWUTS|CLONE_NEWIPC))
> + CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER))
> goto bad_unshare_out;
>
> if ((err = unshare_thread(unshare_flags)))
> diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
> index 1ea8a73..fb00706 100644
> --- a/kernel/nsproxy.c
> +++ b/kernel/nsproxy.c
> @@ -121,7 +121,7 @@ int copy_namespaces(int flags, struct ta
>
> get_nsproxy(old_ns);
>
> - if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
> + if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
> CLONE_NEWUSER)))
> return 0;
>
> if (!capable(CAP_SYS_ADMIN)) {
> @@ -168,9 +168,15 @@ int unshare_nsproxy_namespaces(unsigned
> struct nsproxy *old_ns = current->nsproxy;
> int err = 0;
>
> - if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
> + if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
> + CLONE_NEWUSER)))
> return 0;
>
> +#ifndef CONFIG_USER_NS
> + if (unshare_flags & CLONE_NEWUSER)
> + return -EINVAL;
> +#endif
> +
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
>
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 3d79642..89a27e8 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -21,6 +21,45 @@ EXPORT_SYMBOL_GPL(init_user_ns);
>
> #ifdef CONFIG_USER_NS
>
> +/*
> + * Clone a new ns copying an original user ns, setting refcount to 1
> + * @old_ns: namespace to clone
> + * Return NULL on error (failure to kmalloc), new ns otherwise
> + */
> +static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
> +{
> + struct user_namespace *ns;
> + struct user_struct *new_user;
> + int n;
> +
> + ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
> + if (!ns)
> + return NULL;
> +
> + kref_init(&ns->kref);
> +
> + for (n = 0; n < UIDHASH_SZ; ++n)
> + INIT_LIST_HEAD(ns->uidhash_table + n);
> +
> + /* Insert new root user. */
> + ns->root_user = alloc_uid(ns, 0);
> + if (!ns->root_user) {
> + kfree(ns);
> + return NULL;
> + }
> +
> + /* Reset current->user with a new one */
> + new_user = alloc_uid(ns, current->uid);
> + if (!new_user) {
> + free_uid(ns->root_user);
> + kfree(ns);
> + return NULL;
> + }
> +
> + switch_uid(new_user);
> + return ns;
> +}
> +
> struct user_namespace * copy_user_ns(int flags, struct user_namespace
> *old_ns)
> {
> struct user_namespace *new_ns;
> @@ -28,7 +67,12 @@ struct user_namespace * copy_user_ns(int
> BUG_ON(!old_ns);
> get_user_ns(old_ns);
>
> - new_ns = old_ns;
> + if (!(flags & CLONE_NEWUSER))
> + return old_ns;
> +
> + new_ns = clone_user_ns(old_ns);
> +
> + put_user_ns(old_ns);
> return new_ns;
> }
>
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