Messages in this thread | | | Date | Tue, 29 Nov 2011 18:47:41 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] sysctl: Add the kernel.ns_last_pid control |
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On 11/28, Pavel Emelyanov wrote: > > --- a/kernel/pid_namespace.c > +++ b/kernel/pid_namespace.c > @@ -191,9 +191,40 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) > return; > } > > +static int pid_ns_ctl_handler(struct ctl_table *table, int write, > + void __user *buffer, size_t *lenp, loff_t *ppos) > +{ > + struct ctl_table tmp = *table; > + > + if (write && !capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + /* > + * Writing directly to ns' last_pid field is OK, since this field > + * is volatile in a living namespace anyway and a code writing to > + * it should synchronize its usage with external means. > + */ > + > + tmp.data = ¤t->nsproxy->pid_ns->last_pid; > + return proc_dointvec(&tmp, write, buffer, lenp, ppos); > +} > + > +static struct ctl_table pid_ns_ctl_table[] = { > + { > + .procname = "ns_last_pid", > + .maxlen = sizeof(int), > + .mode = 0666, /* permissions are checked in the handler */ > + .proc_handler = pid_ns_ctl_handler, > + }, > + { } > +}; > + > +static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; > + > static __init int pid_namespaces_init(void) > { > pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); > + register_sysctl_paths(kern_path, pid_ns_ctl_table); > return 0; > }
Hmm. This way it depends on CONFIG_PID_NS.
Can't we simply add an entry into kern_table[] ? And without ns_, just /proc/sys/kernel/last_pid.
Oleg.
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