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SubjectRe: [PATCH 1/4] userns: let clone_uts_ns() handle setting uts->user_ns
On 02/21/2011 05:01 AM, Serge E. Hallyn wrote:
> To do so we need to pass in the task_struct who'll get the utsname,
> so we can get its user_ns.
>
> Signed-off-by: Serge E. Hallyn<serge.hallyn@canonical.com>
> ---


> include/linux/utsname.h | 10 ++++++----
> kernel/nsproxy.c | 7 +------
> kernel/utsname.c | 12 +++++++-----
> 3 files changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/utsname.h b/include/linux/utsname.h
> index 85171be..165b17b 100644
> --- a/include/linux/utsname.h
> +++ b/include/linux/utsname.h
> @@ -52,8 +52,9 @@ static inline void get_uts_ns(struct uts_namespace *ns)
> kref_get(&ns->kref);
> }
>
> -extern struct uts_namespace *copy_utsname(unsigned long flags,
> - struct uts_namespace *ns);
> +extern struct uts_namespace *copy_utsname(struct task_struct *tsk,
> + unsigned long flags,
> + struct uts_namespace *ns);

Why don't we pass 'user_ns' instead of 'tsk' ? that will look
semantically clearer for the caller no ?
(example below).

> extern void free_uts_ns(struct kref *kref);
>
> static inline void put_uts_ns(struct uts_namespace *ns)
> @@ -69,8 +70,9 @@ static inline void put_uts_ns(struct uts_namespace *ns)
> {
> }
>
> -static inline struct uts_namespace *copy_utsname(unsigned long flags,
> - struct uts_namespace *ns)
> +static inline struct uts_namespace *copy_utsname(struct task_struct *tsk,
> + unsigned long flags,
> + struct uts_namespace *ns)
> {
> if (flags& CLONE_NEWUTS)
> return ERR_PTR(-EINVAL);
> diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
> index b6dbff2..ffa6b67 100644
> --- a/kernel/nsproxy.c
> +++ b/kernel/nsproxy.c
> @@ -69,16 +69,11 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
> goto out_ns;
> }
>
> - new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
> + new_nsp->uts_ns = copy_utsname(tsk, flags, tsk->nsproxy->uts_ns);
> if (IS_ERR(new_nsp->uts_ns)) {
> err = PTR_ERR(new_nsp->uts_ns);
> goto out_uts;
> }

...

new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns, task_cred_xxx(tsk, user)->user_ns);

...

> - if (new_nsp->uts_ns != tsk->nsproxy->uts_ns) {
> - put_user_ns(new_nsp->uts_ns->user_ns);
> - new_nsp->uts_ns->user_ns = task_cred_xxx(tsk, user)->user_ns;
> - get_user_ns(new_nsp->uts_ns->user_ns);
> - }
>
> new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
> if (IS_ERR(new_nsp->ipc_ns)) {
> diff --git a/kernel/utsname.c b/kernel/utsname.c
> index a7b3a8d..9462580 100644
> --- a/kernel/utsname.c
> +++ b/kernel/utsname.c
> @@ -31,7 +31,8 @@ static struct uts_namespace *create_uts_ns(void)
> * @old_ns: namespace to clone
> * Return NULL on error (failure to kmalloc), new ns otherwise
> */
> -static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
> +static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
> + struct uts_namespace *old_ns)
> {
> struct uts_namespace *ns;
>
> @@ -41,8 +42,7 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
>
> down_read(&uts_sem);
> memcpy(&ns->name,&old_ns->name, sizeof(ns->name));
> - ns->user_ns = old_ns->user_ns;
> - get_user_ns(ns->user_ns);
> + ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
> up_read(&uts_sem);
> return ns;
> }
> @@ -53,7 +53,9 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
> * utsname of this process won't be seen by parent, and vice
> * versa.
> */
> -struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns)
> +struct uts_namespace *copy_utsname(struct task_struct *tsk,
> + unsigned long flags,
> + struct uts_namespace *old_ns)
> {
> struct uts_namespace *new_ns;
>
> @@ -63,7 +65,7 @@ struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *ol
> if (!(flags& CLONE_NEWUTS))
> return old_ns;
>
> - new_ns = clone_uts_ns(old_ns);
> + new_ns = clone_uts_ns(tsk, old_ns);
>
> put_uts_ns(old_ns);
> return new_ns;



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