pid namespaces: allow cloning of new namespace
When clone() is invoked with CLONE_NEWPID, create a new pid namespace and then
create a new struct pid for the new process. Allocate pid_t's for the new
process in the new pid namespace and all ancestor pid namespaces. Make the
newly cloned process the session and process group leader.
Since the active pid namespace is special and expected to be the first entry
in pid->upid_list, preserve the order of pid namespaces.
The size of 'struct pid' is dependent on the the number of pid namespaces the
process exists in, so we use multiple pid-caches'. Only one pid cache is
created during system startup and this used by processes that exist only in
init_pid_ns.
When a process clones its pid namespace, we create additional pid caches as
necessary and use the pid cache to allocate 'struct pids' for that depth.
Note, that with this patch the newly created namespace won't work, since the
rest of the kernel still uses global pids, but this is to be fixed soon. Init
pid namespace still works.
[oleg@tv-sign.ru: merge fix]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/fork.c b/kernel/fork.c
index bab3419..f252784 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -973,7 +973,6 @@
unsigned long stack_start,
struct pt_regs *regs,
unsigned long stack_size,
- int __user *parent_tidptr,
int __user *child_tidptr,
struct pid *pid)
{
@@ -1043,11 +1042,6 @@
p->did_exec = 0;
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
copy_flags(clone_flags, p);
- retval = -EFAULT;
- if (clone_flags & CLONE_PARENT_SETTID)
- if (put_user(p->pid, parent_tidptr))
- goto bad_fork_cleanup_delays_binfmt;
-
INIT_LIST_HEAD(&p->children);
INIT_LIST_HEAD(&p->sibling);
p->vfork_done = NULL;
@@ -1289,11 +1283,22 @@
__ptrace_link(p, current->parent);
if (thread_group_leader(p)) {
- p->signal->tty = current->signal->tty;
- p->signal->pgrp = task_pgrp_nr(current);
- set_task_session(p, task_session_nr(current));
- attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
- attach_pid(p, PIDTYPE_SID, task_session(current));
+ if (clone_flags & CLONE_NEWPID) {
+ p->nsproxy->pid_ns->child_reaper = p;
+ p->signal->tty = NULL;
+ p->signal->pgrp = p->pid;
+ set_task_session(p, p->pid);
+ attach_pid(p, PIDTYPE_PGID, pid);
+ attach_pid(p, PIDTYPE_SID, pid);
+ } else {
+ p->signal->tty = current->signal->tty;
+ p->signal->pgrp = task_pgrp_nr(current);
+ set_task_session(p, task_session_nr(current));
+ attach_pid(p, PIDTYPE_PGID,
+ task_pgrp(current));
+ attach_pid(p, PIDTYPE_SID,
+ task_session(current));
+ }
list_add_tail_rcu(&p->tasks, &init_task.tasks);
__get_cpu_var(process_counts)++;
@@ -1339,7 +1344,6 @@
bad_fork_cleanup_cgroup:
#endif
cgroup_exit(p, cgroup_callbacks_done);
-bad_fork_cleanup_delays_binfmt:
delayacct_tsk_free(p);
if (p->binfmt)
module_put(p->binfmt->module);
@@ -1366,7 +1370,7 @@
struct task_struct *task;
struct pt_regs regs;
- task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL,
+ task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
&init_struct_pid);
if (!IS_ERR(task))
init_idle(task, cpu);
@@ -1414,7 +1418,7 @@
}
p = copy_process(clone_flags, stack_start, regs, stack_size,
- parent_tidptr, child_tidptr, NULL);
+ child_tidptr, NULL);
/*
* Do this prior waking up the new thread - the thread pointer
* might get invalid after that point, if the thread exits quickly.
@@ -1422,7 +1426,16 @@
if (!IS_ERR(p)) {
struct completion vfork;
- nr = pid_nr(task_pid(p));
+ /*
+ * this is enough to call pid_nr_ns here, but this if
+ * improves optimisation of regular fork()
+ */
+ nr = (clone_flags & CLONE_NEWPID) ?
+ task_pid_nr_ns(p, current->nsproxy->pid_ns) :
+ task_pid_vnr(p);
+
+ if (clone_flags & CLONE_PARENT_SETTID)
+ put_user(nr, parent_tidptr);
if (clone_flags & CLONE_VFORK) {
p->vfork_done = &vfork;
