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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/pid.h>#include <linux/pid_namespace.h>#include <linux/user_namespace.h>#include <linux/syscalls.h>#include <linux/cred.h>#include <linux/err.h>#include <linux/acct.h>#include <linux/slab.h>#include <linux/proc_ns.h>#include <linux/reboot.h>#include <linux/export.h>#include <linux/sched/task.h>#include <linux/sched/signal.h>#include <linux/idr.h>#include <linux/nstree.h>#include <uapi/linux/wait.h>#include "pid_sysctl.h"
static DEFINE_MUTEX(pid_caches_mutex);static struct kmem_cache *pid_ns_cachep;/* Write once array, filled from the beginning. */static struct kmem_cache *pid_cache[MAX_PID_NS_LEVEL];
/* * creates the kmem cache to allocate pids from. * @level: pid namespace level */
static struct kmem_cache *create_pid_cachep(unsigned int level){ /* Level 0 is init_pid_ns.pid_cachep */ struct kmem_cache **pkc = &pid_cache[level - 1]; struct kmem_cache *kc; char name[4 + 10 + 1]; unsigned int len;
kc = READ_ONCE(*pkc); if (kc) return kc;
snprintf(name, sizeof(name), "pid_%u", level + 1); len = struct_size_t(struct pid, numbers, level + 1); mutex_lock(&pid_caches_mutex); /* Name collision forces to do allocation under mutex. */ if (!*pkc) *pkc = kmem_cache_create(name, len, 0, SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, NULL); mutex_unlock(&pid_caches_mutex); /* current can fail, but someone else can succeed. */ return READ_ONCE(*pkc);}
static struct ucounts *inc_pid_namespaces(struct user_namespace *ns){ return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);}
static void dec_pid_namespaces(struct ucounts *ucounts){ dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);}
static void destroy_pid_namespace_work(struct work_struct *work);
static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns, struct pid_namespace *parent_pid_ns){ struct pid_namespace *ns; unsigned int level = parent_pid_ns->level + 1; struct ucounts *ucounts; int err;
err = -EINVAL; if (!in_userns(parent_pid_ns->user_ns, user_ns)) goto out;
err = -ENOSPC; if (level > MAX_PID_NS_LEVEL) goto out; ucounts = inc_pid_namespaces(user_ns); if (!ucounts) goto out;
err = -ENOMEM; ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); if (ns == NULL) goto out_dec;
idr_init(&ns->idr);
ns->pid_cachep = create_pid_cachep(level); if (ns->pid_cachep == NULL) goto out_free_idr;
err = ns_common_init(ns); if (err) goto out_free_idr;
ns->pid_max = PID_MAX_LIMIT; err = register_pidns_sysctls(ns); if (err) goto out_free_inum;
ns->level = level; ns->parent = get_pid_ns(parent_pid_ns); ns->user_ns = get_user_ns(user_ns); ns->ucounts = ucounts; ns->pid_allocated = PIDNS_ADDING; INIT_WORK(&ns->work, destroy_pid_namespace_work);
#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE) ns->memfd_noexec_scope = pidns_memfd_noexec_scope(parent_pid_ns);#endif
ns_tree_add(ns); return ns;
out_free_inum: ns_common_free(ns);out_free_idr: idr_destroy(&ns->idr); kmem_cache_free(pid_ns_cachep, ns);out_dec: dec_pid_namespaces(ucounts);out: return ERR_PTR(err);}
static void delayed_free_pidns(struct rcu_head *p){ struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);
dec_pid_namespaces(ns->ucounts); put_user_ns(ns->user_ns);
kmem_cache_free(pid_ns_cachep, ns);}
static void destroy_pid_namespace(struct pid_namespace *ns){ ns_tree_remove(ns); unregister_pidns_sysctls(ns);
ns_common_free(ns);
idr_destroy(&ns->idr); call_rcu(&ns->rcu, delayed_free_pidns);}
static void destroy_pid_namespace_work(struct work_struct *work){ struct pid_namespace *ns = container_of(work, struct pid_namespace, work);
do { struct pid_namespace *parent;
parent = ns->parent; destroy_pid_namespace(ns); ns = parent; } while (ns != &init_pid_ns && ns_ref_put(ns));}
struct pid_namespace *copy_pid_ns(u64 flags, struct user_namespace *user_ns, struct pid_namespace *old_ns){ if (!(flags & CLONE_NEWPID)) return get_pid_ns(old_ns); if (task_active_pid_ns(current) != old_ns) return ERR_PTR(-EINVAL); return create_pid_namespace(user_ns, old_ns);}
void put_pid_ns(struct pid_namespace *ns){ if (ns && ns_ref_put(ns)) schedule_work(&ns->work);}EXPORT_SYMBOL_GPL(put_pid_ns);
void zap_pid_ns_processes(struct pid_namespace *pid_ns){ int nr; int rc; struct task_struct *task, *me = current; int init_pids = thread_group_leader(me) ? 1 : 2; struct pid *pid;
/* Don't allow any more processes into the pid namespace */ disable_pid_allocation(pid_ns);
/* * Ignore SIGCHLD causing any terminated children to autoreap. * This speeds up the namespace shutdown, plus see the comment * below. */ spin_lock_irq(&me->sighand->siglock); me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN; spin_unlock_irq(&me->sighand->siglock);
/* * The last thread in the cgroup-init thread group is terminating. * Find remaining pid_ts in the namespace, signal and wait for them * to exit. * * Note: This signals each threads in the namespace - even those that * belong to the same thread group, To avoid this, we would have * to walk the entire tasklist looking a processes in this * namespace, but that could be unnecessarily expensive if the * pid namespace has just a few processes. Or we need to * maintain a tasklist for each pid namespace. * */ rcu_read_lock(); read_lock(&tasklist_lock); nr = 2; idr_for_each_entry_continue(&pid_ns->idr, pid, nr) { task = pid_task(pid, PIDTYPE_PID); if (task && !__fatal_signal_pending(task)) group_send_sig_info(SIGKILL, SEND_SIG_PRIV, task, PIDTYPE_MAX); } read_unlock(&tasklist_lock); rcu_read_unlock();
/* * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD. * kernel_wait4() will also block until our children traced from the * parent namespace are detached and become EXIT_DEAD. */ do { clear_thread_flag(TIF_SIGPENDING); clear_thread_flag(TIF_NOTIFY_SIGNAL); rc = kernel_wait4(-1, NULL, __WALL, NULL); } while (rc != -ECHILD);
/* * kernel_wait4() misses EXIT_DEAD children, and EXIT_ZOMBIE * process whose parents processes are outside of the pid * namespace. Such processes are created with setns()+fork(). * * If those EXIT_ZOMBIE processes are not reaped by their * parents before their parents exit, they will be reparented * to pid_ns->child_reaper. Thus pidns->child_reaper needs to * stay valid until they all go away. * * The code relies on the pid_ns->child_reaper ignoring * SIGCHILD to cause those EXIT_ZOMBIE processes to be * autoreaped if reparented. * * Semantically it is also desirable to wait for EXIT_ZOMBIE * processes before allowing the child_reaper to be reaped, as * that gives the invariant that when the init process of a * pid namespace is reaped all of the processes in the pid * namespace are gone. * * Once all of the other tasks are gone from the pid_namespace * free_pid() will awaken this task. */ for (;;) { set_current_state(TASK_INTERRUPTIBLE); if (pid_ns->pid_allocated == init_pids) break; schedule(); } __set_current_state(TASK_RUNNING);
if (pid_ns->reboot) current->signal->group_exit_code = pid_ns->reboot;
acct_exit_ns(pid_ns); return;}
#ifdef CONFIG_CHECKPOINT_RESTOREstatic int pid_ns_ctl_handler(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos){ struct pid_namespace *pid_ns = task_active_pid_ns(current); struct ctl_table tmp = *table; int ret, next;
if (write && !checkpoint_restore_ns_capable(pid_ns->user_ns)) return -EPERM;
next = idr_get_cursor(&pid_ns->idr) - 1;
tmp.data = &next; tmp.extra2 = &pid_ns->pid_max; ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); if (!ret && write) idr_set_cursor(&pid_ns->idr, next + 1);
return ret;}
static const 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, .extra1 = SYSCTL_ZERO, .extra2 = &init_pid_ns.pid_max, },};#endif /* CONFIG_CHECKPOINT_RESTORE */
int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd){ if (pid_ns == &init_pid_ns) return 0;
switch (cmd) { case LINUX_REBOOT_CMD_RESTART2: case LINUX_REBOOT_CMD_RESTART: pid_ns->reboot = SIGHUP; break;
case LINUX_REBOOT_CMD_POWER_OFF: case LINUX_REBOOT_CMD_HALT: pid_ns->reboot = SIGINT; break; default: return -EINVAL; }
read_lock(&tasklist_lock); send_sig(SIGKILL, pid_ns->child_reaper, 1); read_unlock(&tasklist_lock);
do_exit(0);
/* Not reached */ return 0;}
static struct ns_common *pidns_get(struct task_struct *task){ struct pid_namespace *ns;
rcu_read_lock(); ns = task_active_pid_ns(task); if (ns) get_pid_ns(ns); rcu_read_unlock();
return ns ? &ns->ns : NULL;}
static struct ns_common *pidns_for_children_get(struct task_struct *task){ struct pid_namespace *ns = NULL;
task_lock(task); if (task->nsproxy) { ns = task->nsproxy->pid_ns_for_children; get_pid_ns(ns); } task_unlock(task);
return ns ? &ns->ns : NULL;}
static void pidns_put(struct ns_common *ns){ put_pid_ns(to_pid_ns(ns));}
bool pidns_is_ancestor(struct pid_namespace *child, struct pid_namespace *ancestor){ struct pid_namespace *ns;
if (child->level < ancestor->level) return false; for (ns = child; ns->level > ancestor->level; ns = ns->parent) ; return ns == ancestor;}
static int pidns_install(struct nsset *nsset, struct ns_common *ns){ struct nsproxy *nsproxy = nsset->nsproxy; struct pid_namespace *active = task_active_pid_ns(current); struct pid_namespace *new = to_pid_ns(ns);
if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) || !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN)) return -EPERM;
/* * Only allow entering the current active pid namespace * or a child of the current active pid namespace. * * This is required for fork to return a usable pid value and * this maintains the property that processes and their * children can not escape their current pid namespace. */ if (!pidns_is_ancestor(new, active)) return -EINVAL;
put_pid_ns(nsproxy->pid_ns_for_children); nsproxy->pid_ns_for_children = get_pid_ns(new); return 0;}
static struct ns_common *pidns_get_parent(struct ns_common *ns){ struct pid_namespace *active = task_active_pid_ns(current); struct pid_namespace *pid_ns, *p;
/* See if the parent is in the current namespace */ pid_ns = p = to_pid_ns(ns)->parent; for (;;) { if (!p) return ERR_PTR(-EPERM); if (p == active) break; p = p->parent; }
return &get_pid_ns(pid_ns)->ns;}
static struct user_namespace *pidns_owner(struct ns_common *ns){ return to_pid_ns(ns)->user_ns;}
const struct proc_ns_operations pidns_operations = { .name = "pid", .get = pidns_get, .put = pidns_put, .install = pidns_install, .owner = pidns_owner, .get_parent = pidns_get_parent,};
const struct proc_ns_operations pidns_for_children_operations = { .name = "pid_for_children", .real_ns_name = "pid", .get = pidns_for_children_get, .put = pidns_put, .install = pidns_install, .owner = pidns_owner, .get_parent = pidns_get_parent,};
static __init int pid_namespaces_init(void){ pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC | SLAB_ACCOUNT);
#ifdef CONFIG_CHECKPOINT_RESTORE register_sysctl_init("kernel", pid_ns_ctl_table);#endif
register_pid_ns_sysctl_table_vm(); ns_tree_add(&init_pid_ns); return 0;}
__initcall(pid_namespaces_init);