pid namespaces: make alloc_pid(), free_pid() and put_pid() work with struct upid

Each struct upid element of struct pid has to be initialized properly, i.e.
its nr mst be allocated from appropriate pidmap and ns set to appropriate
namespace.

When allocating a new pid, we need to know the namespace this pid will live
in, so the additional argument is added to alloc_pid().

On the other hand, the rest of the kernel still uses the pid->nr and
pid->pid_chain fields, so these ones are still initialized, but this will be
removed soon.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/pid.h b/include/linux/pid.h
index e5865a9c58a6ab07bd9a909cbfd254028e17f5fe..67470ade32123c022b0b4a44d96eccceadc509da 100644 (file)
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -111,7 +111,7 @@ extern struct pid *FASTCALL(find_pid(int nr));
 extern struct pid *find_get_pid(int nr);
 extern struct pid *find_ge_pid(int nr);
 
-extern struct pid *alloc_pid(void);
+extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
 
 static inline pid_t pid_nr(struct pid *pid)

diff --git a/kernel/fork.c b/kernel/fork.c
index d2f4a420a5b9765b04b2a40a98db679145fda462..984d259e172d01c41d22fc458dec66c24f693fd4 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1041,7 +1041,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                goto bad_fork_cleanup_put_domain;
 
        if (pid != &init_struct_pid) {
-               pid = alloc_pid();
+               pid = alloc_pid(task_active_pid_ns(p));
                if (!pid)
                        goto bad_fork_put_binfmt_module;
        }

diff --git a/kernel/pid.c b/kernel/pid.c
index c7346fb801fca1f468f537722f349e2225a15c62..8132a6ddfa10b18396fe07bf53325b44a7628d7d 100644 (file)
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -29,7 +29,8 @@
 #include <linux/pid_namespace.h>
 #include <linux/init_task.h>
 
-#define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
+#define pid_hashfn(nr, ns)     \
+       hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
 static struct hlist_head *pid_hash;
 static int pidhash_shift;
 struct pid init_struct_pid = INIT_STRUCT_PID;
@@ -186,11 +187,13 @@ fastcall void put_pid(struct pid *pid)
        if (!pid)
                return;
 
-       /* FIXME - this must be the namespace this pid lives in */
-       ns = &init_pid_ns;
+       ns = pid->numbers[pid->level].ns;
        if ((atomic_read(&pid->count) == 1) ||
-            atomic_dec_and_test(&pid->count))
+            atomic_dec_and_test(&pid->count)) {
                kmem_cache_free(ns->pid_cachep, pid);
+               if (ns != &init_pid_ns)
+                       put_pid_ns(ns);
+       }
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -203,45 +206,61 @@ static void delayed_put_pid(struct rcu_head *rhp)
 fastcall void free_pid(struct pid *pid)
 {
        /* We can be called with write_lock_irq(&tasklist_lock) held */
+       int i;
        unsigned long flags;
 
        spin_lock_irqsave(&pidmap_lock, flags);
        hlist_del_rcu(&pid->pid_chain);
        spin_unlock_irqrestore(&pidmap_lock, flags);
 
-       free_pidmap(&init_pid_ns, pid->nr);
+       for (i = 0; i <= pid->level; i++)
+               free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
        call_rcu(&pid->rcu, delayed_put_pid);
 }
 
-struct pid *alloc_pid(void)
+struct pid *alloc_pid(struct pid_namespace *ns)
 {
        struct pid *pid;
        enum pid_type type;
-       int nr = -1;
-       struct pid_namespace *ns;
+       int i, nr;
+       struct pid_namespace *tmp;
 
-       ns = task_active_pid_ns(current);
        pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
        if (!pid)
                goto out;
 
-       nr = alloc_pidmap(ns);
-       if (nr < 0)
-               goto out_free;
+       tmp = ns;
+       for (i = ns->level; i >= 0; i--) {
+               nr = alloc_pidmap(tmp);
+               if (nr < 0)
+                       goto out_free;
 
+               pid->numbers[i].nr = nr;
+               pid->numbers[i].ns = tmp;
+               tmp = tmp->parent;
+       }
+
+       if (ns != &init_pid_ns)
+               get_pid_ns(ns);
+
+       pid->level = ns->level;
+       pid->nr = pid->numbers[0].nr;
        atomic_set(&pid->count, 1);
-       pid->nr = nr;
        for (type = 0; type < PIDTYPE_MAX; ++type)
                INIT_HLIST_HEAD(&pid->tasks[type]);
 
        spin_lock_irq(&pidmap_lock);
-       hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr)]);
+       hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr, ns)]);
        spin_unlock_irq(&pidmap_lock);
 
 out:
        return pid;
 
 out_free:
+       for (i++; i <= ns->level; i++)
+               free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
        kmem_cache_free(ns->pid_cachep, pid);
        pid = NULL;
        goto out;
@@ -253,7 +272,7 @@ struct pid * fastcall find_pid(int nr)
        struct pid *pid;
 
        hlist_for_each_entry_rcu(pid, elem,
-                       &pid_hash[pid_hashfn(nr)], pid_chain) {
+                       &pid_hash[pid_hashfn(nr, &init_pid_ns)], pid_chain) {
                if (pid->nr == nr)
                        return pid;
        }