linux-kernel - Re: [CFT][PATCH 6/8] userns: Rename id_map_mutex to userns_state

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Message-ID: <CALCETrXffwu6+yn76FXB2xnk+2GQq5UZSxXokOk8pxsHz6Ye_Q@mail.gmail.com>
Date:	Tue, 9 Dec 2014 14:49:32 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Linux Containers <containers@...ts.linux-foundation.org>,
	Josh Triplett <josh@...htriplett.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <keescook@...omium.org>,
	Michael Kerrisk-manpages <mtk.manpages@...il.com>,
	Linux API <linux-api@...r.kernel.org>,
	linux-man <linux-man@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	LSM <linux-security-module@...r.kernel.org>,
	Casey Schaufler <casey@...aufler-ca.com>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Richard Weinberger <richard@....at>,
	Kenton Varda <kenton@...dstorm.io>,
	stable <stable@...r.kernel.org>
Subject: Re: [CFT][PATCH 6/8] userns: Rename id_map_mutex to userns_state_mutex

On Tue, Dec 9, 2014 at 12:41 PM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
>
> Generalize id_map_mutex so it can be used for more state of a user namespace.

Reviewed-by: Andy Lutomirski <luto@...capital.net>

>
> Cc: stable@...r.kernel.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
> ---
>  kernel/user_namespace.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 1e34de2fbd60..44a555ac6104 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -24,6 +24,7 @@
>  #include <linux/fs_struct.h>
>
>  static struct kmem_cache *user_ns_cachep __read_mostly;
> +static DEFINE_MUTEX(userns_state_mutex);
>
>  static bool new_idmap_permitted(const struct file *file,
>                                 struct user_namespace *ns, int cap_setid,
> @@ -583,9 +584,6 @@ static bool mappings_overlap(struct uid_gid_map *new_map,
>         return false;
>  }
>
> -
> -static DEFINE_MUTEX(id_map_mutex);
> -
>  static ssize_t map_write(struct file *file, const char __user *buf,
>                          size_t count, loff_t *ppos,
>                          int cap_setid,
> @@ -602,7 +600,7 @@ static ssize_t map_write(struct file *file, const char __user *buf,
>         ssize_t ret = -EINVAL;
>
>         /*
> -        * The id_map_mutex serializes all writes to any given map.
> +        * The userns_state_mutex serializes all writes to any given map.
>          *
>          * Any map is only ever written once.
>          *
> @@ -620,7 +618,7 @@ static ssize_t map_write(struct file *file, const char __user *buf,
>          * order and smp_rmb() is guaranteed that we don't have crazy
>          * architectures returning stale data.
>          */
> -       mutex_lock(&id_map_mutex);
> +       mutex_lock(&userns_state_mutex);
>
>         ret = -EPERM;
>         /* Only allow one successful write to the map */
> @@ -750,7 +748,7 @@ static ssize_t map_write(struct file *file, const char __user *buf,
>         *ppos = count;
>         ret = count;
>  out:
> -       mutex_unlock(&id_map_mutex);
> +       mutex_unlock(&userns_state_mutex);
>         if (page)
>                 free_page(page);
>         return ret;
> @@ -845,12 +843,12 @@ bool userns_may_setgroups(const struct user_namespace *ns)
>  {
>         bool allowed;
>
> -       mutex_lock(&id_map_mutex);
> +       mutex_lock(&userns_state_mutex);
>         /* It is not safe to use setgroups until a gid mapping in
>          * the user namespace has been established.
>          */
>         allowed = ns->gid_map.nr_extents != 0;
> -       mutex_unlock(&id_map_mutex);
> +       mutex_unlock(&userns_state_mutex);
>
>         return allowed;
>  }
> --
> 1.9.1
>



-- 
Andy Lutomirski
AMA Capital Management, LLC
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