diff options
Diffstat (limited to 'kernel/pid.c')
| -rw-r--r-- | kernel/pid.c | 72 |
1 files changed, 57 insertions, 15 deletions
diff --git a/kernel/pid.c b/kernel/pid.c index 7b5f6c963d72..2278e249141d 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -157,7 +157,8 @@ void free_pid(struct pid *pid) call_rcu(&pid->rcu, delayed_put_pid); } -struct pid *alloc_pid(struct pid_namespace *ns) +struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid, + size_t set_tid_size) { struct pid *pid; enum pid_type type; @@ -166,6 +167,17 @@ struct pid *alloc_pid(struct pid_namespace *ns) struct upid *upid; int retval = -ENOMEM; + /* + * set_tid_size contains the size of the set_tid array. Starting at + * the most nested currently active PID namespace it tells alloc_pid() + * which PID to set for a process in that most nested PID namespace + * up to set_tid_size PID namespaces. It does not have to set the PID + * for a process in all nested PID namespaces but set_tid_size must + * never be greater than the current ns->level + 1. + */ + if (set_tid_size > ns->level + 1) + return ERR_PTR(-EINVAL); + pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL); if (!pid) return ERR_PTR(retval); @@ -174,24 +186,54 @@ struct pid *alloc_pid(struct pid_namespace *ns) pid->level = ns->level; for (i = ns->level; i >= 0; i--) { - int pid_min = 1; + int tid = 0; + + if (set_tid_size) { + tid = set_tid[ns->level - i]; + + retval = -EINVAL; + if (tid < 1 || tid >= pid_max) + goto out_free; + /* + * Also fail if a PID != 1 is requested and + * no PID 1 exists. + */ + if (tid != 1 && !tmp->child_reaper) + goto out_free; + retval = -EPERM; + if (!ns_capable(tmp->user_ns, CAP_SYS_ADMIN)) + goto out_free; + set_tid_size--; + } idr_preload(GFP_KERNEL); spin_lock_irq(&pidmap_lock); - /* - * init really needs pid 1, but after reaching the maximum - * wrap back to RESERVED_PIDS - */ - if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS) - pid_min = RESERVED_PIDS; - - /* - * Store a null pointer so find_pid_ns does not find - * a partially initialized PID (see below). - */ - nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min, - pid_max, GFP_ATOMIC); + if (tid) { + nr = idr_alloc(&tmp->idr, NULL, tid, + tid + 1, GFP_ATOMIC); + /* + * If ENOSPC is returned it means that the PID is + * alreay in use. Return EEXIST in that case. + */ + if (nr == -ENOSPC) + nr = -EEXIST; + } else { + int pid_min = 1; + /* + * init really needs pid 1, but after reaching the + * maximum wrap back to RESERVED_PIDS + */ + if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS) + pid_min = RESERVED_PIDS; + + /* + * Store a null pointer so find_pid_ns does not find + * a partially initialized PID (see below). + */ + nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min, + pid_max, GFP_ATOMIC); + } spin_unlock_irq(&pidmap_lock); idr_preload_end(); |