A current problem with the pid namespace is that it is easy to do pid related work after exit_task_namespaces which drops the nsproxy pointer. However if we are doing pid namespace related work we are always operating on some struct pid which retains the pid_namespace pointer of the pid namespace it was allocated in. So provide ns_of_pid which allows us to find the pid namespace a pid was allocated in. Using this we have the needed infrastructure to do pid namespace related work at anytime we have a struct pid, removing the chance of accidentally having a NULL pointer dereference when accessing current->nsproxy. Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> --- include/linux/pid.h | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/include/linux/pid.h b/include/linux/pid.h index f84d532..c4b56c0 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -123,6 +123,17 @@ int next_pidmap(struct pid_namespace *pid_ns, int last); extern struct pid *alloc_pid(struct pid_namespace *ns); extern void FASTCALL(free_pid(struct pid *pid)); +/* ns_of_pid returns the pid namespace in which the specified + * pid was allocated. + */ +static inline struct pid_namespace *ns_of_pid(struct pid *pid) +{ + struct pid_namespace *ns = NULL; + if (pid) + ns = pid->numbers[pid->level].ns; + return ns; +} + /* * the helpers to get the pid's id seen from different namespaces * -- 1.5.3.rc6.17.g1911 _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers