Messages in this thread | | | Date | Fri, 29 May 2015 15:21:43 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 1/1] /proc/$PID/status : show list NSpid data based on current process namespace. |
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On Fri, 29 May 2015 11:57:21 +0900 Kuenhwan Kwak <kh243.kwak@samsung.com> wrote:
> This patch helps creating a pid mapping data to parent processes. > > Reading 'NSpid' field in '/proc/$PID/status' is currently a simple > way to getting child pid from parent pid in userspace. But this field > supplies only single direction mapping('parent pid' to 'child pid'). > If parent process want to translate child pid to current namespace pid, > there is no way to get except full searching in current procfs. > > This patch will helps in getting current namespace pid by reading child > procfs file without any side effects. > > For example, Process id is 24771 in level 0, 435 in level 1. > a) The output of '/proc/24771/status' in level 0 namespace. > NSpid : 24771 435 > > b) The output of '/proc/435/status' in level 1 namespace. > NSpid : 435 > > c) Process in level 0 mount level1 proc to '/var/child/proc' > after setns(). The output of '/var/child/proc/435/status' is > NSpid : 24771 435 > > ... > > --- a/fs/proc/array.c > +++ b/fs/proc/array.c > @@ -83,6 +83,7 @@ > #include <linux/tracehook.h> > #include <linux/string_helpers.h> > #include <linux/user_namespace.h> > +#include <linux/sched.h> > > #include <asm/pgtable.h> > #include <asm/processor.h> > @@ -149,6 +150,9 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, > const struct cred *cred; > pid_t ppid, tpid = 0, tgid, ngid; > unsigned int max_fds = 0; > +#ifdef CONFIG_PID_NS > + struct pid_namespace *current_pid_ns = task_active_pid_ns(current); > +#endif > > rcu_read_lock(); > ppid = pid_alive(p) ? > @@ -198,19 +202,19 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, > > #ifdef CONFIG_PID_NS > seq_puts(m, "\nNStgid:"); > - for (g = ns->level; g <= pid->level; g++) > + for (g = current_pid_ns->level; g <= pid->level; g++) > seq_printf(m, "\t%d", > task_tgid_nr_ns(p, pid->numbers[g].ns)); > seq_puts(m, "\nNSpid:"); > - for (g = ns->level; g <= pid->level; g++) > + for (g = current_pid_ns->level; g <= pid->level; g++) > seq_printf(m, "\t%d", > task_pid_nr_ns(p, pid->numbers[g].ns)); > seq_puts(m, "\nNSpgid:"); > - for (g = ns->level; g <= pid->level; g++) > + for (g = current_pid_ns->level; g <= pid->level; g++) > seq_printf(m, "\t%d", > task_pgrp_nr_ns(p, pid->numbers[g].ns)); > seq_puts(m, "\nNSsid:"); > - for (g = ns->level; g <= pid->level; g++) > + for (g = current_pid_ns->level; g <= pid->level; g++) > seq_printf(m, "\t%d", > task_session_nr_ns(p, pid->numbers[g].ns));
These changes alter current behaviour, don't they? How do we know this won't impact existing userspace code?
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