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    Subject[PATCH 03/10] allow sethostname in a container
    Changelog:
    Feb 23: let clone_uts_ns() handle setting uts->user_ns
    To do so we need to pass in the task_struct who'll
    get the utsname, so we can get its user_ns.
    Feb 23: As per Oleg's coment, just pass in tsk, instead of two
    of its members.

    Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
    Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
    Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
    ---
    include/linux/utsname.h | 6 +++---
    kernel/nsproxy.c | 7 +------
    kernel/sys.c | 2 +-
    kernel/utsname.c | 12 +++++++-----
    4 files changed, 12 insertions(+), 15 deletions(-)

    diff --git a/include/linux/utsname.h b/include/linux/utsname.h
    index 2c3c0f5..4e5b021 100644
    --- a/include/linux/utsname.h
    +++ b/include/linux/utsname.h
    @@ -54,7 +54,7 @@ static inline void get_uts_ns(struct uts_namespace *ns)
    }

    extern struct uts_namespace *copy_utsname(unsigned long flags,
    - struct uts_namespace *ns);
    + struct task_struct *tsk);
    extern void free_uts_ns(struct kref *kref);

    static inline void put_uts_ns(struct uts_namespace *ns)
    @@ -71,12 +71,12 @@ static inline void put_uts_ns(struct uts_namespace *ns)
    }

    static inline struct uts_namespace *copy_utsname(unsigned long flags,
    - struct uts_namespace *ns)
    + struct task_struct *tsk)
    {
    if (flags & CLONE_NEWUTS)
    return ERR_PTR(-EINVAL);

    - return ns;
    + return tsk->nsproxy->uts_ns;
    }
    #endif

    diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
    index 034dc2e..b97fc9d 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(flags, tsk);
    if (IS_ERR(new_nsp->uts_ns)) {
    err = PTR_ERR(new_nsp->uts_ns);
    goto out_uts;
    }
    - 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/sys.c b/kernel/sys.c
    index 18da702..7a1bbad 100644
    --- a/kernel/sys.c
    +++ b/kernel/sys.c
    @@ -1177,7 +1177,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
    int errno;
    char tmp[__NEW_UTS_LEN];

    - if (!capable(CAP_SYS_ADMIN))
    + if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
    return -EPERM;
    if (len < 0 || len > __NEW_UTS_LEN)
    return -EINVAL;
    diff --git a/kernel/utsname.c b/kernel/utsname.c
    index a7b3a8d..4464617 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;
    }
    @@ -53,8 +53,10 @@ 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(unsigned long flags,
    + struct task_struct *tsk)
    {
    + struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
    struct uts_namespace *new_ns;

    BUG_ON(!old_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;
    --
    1.7.0.4


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