On Tue, Dec 9, 2014 at 12:41 PM, Eric W. Biederman
<ebiederm@xxxxxxxxxxxx> wrote:
>
> Generalize id_map_mutex so it can be used for more state of a user namespace.
Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
> ---
> 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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