Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Pid namespaces |
| 3 | * |
| 4 | * Authors: |
| 5 | * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc. |
| 6 | * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM |
| 7 | * Many thanks to Oleg Nesterov for comments and help |
| 8 | * |
| 9 | */ |
| 10 | |
| 11 | #include <linux/pid.h> |
| 12 | #include <linux/pid_namespace.h> |
| 13 | #include <linux/syscalls.h> |
| 14 | #include <linux/err.h> |
Pavel Emelyanov | 0b6b030 | 2008-07-25 01:48:47 -0700 | [diff] [blame] | 15 | #include <linux/acct.h> |
Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 16 | |
| 17 | #define BITS_PER_PAGE (PAGE_SIZE*8) |
| 18 | |
| 19 | struct pid_cache { |
| 20 | int nr_ids; |
| 21 | char name[16]; |
| 22 | struct kmem_cache *cachep; |
| 23 | struct list_head list; |
| 24 | }; |
| 25 | |
| 26 | static LIST_HEAD(pid_caches_lh); |
| 27 | static DEFINE_MUTEX(pid_caches_mutex); |
| 28 | static struct kmem_cache *pid_ns_cachep; |
| 29 | |
| 30 | /* |
| 31 | * creates the kmem cache to allocate pids from. |
| 32 | * @nr_ids: the number of numerical ids this pid will have to carry |
| 33 | */ |
| 34 | |
| 35 | static struct kmem_cache *create_pid_cachep(int nr_ids) |
| 36 | { |
| 37 | struct pid_cache *pcache; |
| 38 | struct kmem_cache *cachep; |
| 39 | |
| 40 | mutex_lock(&pid_caches_mutex); |
| 41 | list_for_each_entry(pcache, &pid_caches_lh, list) |
| 42 | if (pcache->nr_ids == nr_ids) |
| 43 | goto out; |
| 44 | |
| 45 | pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL); |
| 46 | if (pcache == NULL) |
| 47 | goto err_alloc; |
| 48 | |
| 49 | snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids); |
| 50 | cachep = kmem_cache_create(pcache->name, |
| 51 | sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid), |
| 52 | 0, SLAB_HWCACHE_ALIGN, NULL); |
| 53 | if (cachep == NULL) |
| 54 | goto err_cachep; |
| 55 | |
| 56 | pcache->nr_ids = nr_ids; |
| 57 | pcache->cachep = cachep; |
| 58 | list_add(&pcache->list, &pid_caches_lh); |
| 59 | out: |
| 60 | mutex_unlock(&pid_caches_mutex); |
| 61 | return pcache->cachep; |
| 62 | |
| 63 | err_cachep: |
| 64 | kfree(pcache); |
| 65 | err_alloc: |
| 66 | mutex_unlock(&pid_caches_mutex); |
| 67 | return NULL; |
| 68 | } |
| 69 | |
Pavel Emelyanov | caafa43 | 2008-04-30 00:54:31 -0700 | [diff] [blame] | 70 | static struct pid_namespace *create_pid_namespace(unsigned int level) |
Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 71 | { |
| 72 | struct pid_namespace *ns; |
| 73 | int i; |
| 74 | |
Pavel Emelyanov | 84406c1 | 2008-07-25 01:48:42 -0700 | [diff] [blame] | 75 | ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 76 | if (ns == NULL) |
| 77 | goto out; |
| 78 | |
| 79 | ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
| 80 | if (!ns->pidmap[0].page) |
| 81 | goto out_free; |
| 82 | |
| 83 | ns->pid_cachep = create_pid_cachep(level + 1); |
| 84 | if (ns->pid_cachep == NULL) |
| 85 | goto out_free_map; |
| 86 | |
| 87 | kref_init(&ns->kref); |
Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 88 | ns->level = level; |
| 89 | |
| 90 | set_bit(0, ns->pidmap[0].page); |
| 91 | atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); |
| 92 | |
Pavel Emelyanov | 84406c1 | 2008-07-25 01:48:42 -0700 | [diff] [blame] | 93 | for (i = 1; i < PIDMAP_ENTRIES; i++) |
Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 94 | atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); |
Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 95 | |
| 96 | return ns; |
| 97 | |
| 98 | out_free_map: |
| 99 | kfree(ns->pidmap[0].page); |
| 100 | out_free: |
| 101 | kmem_cache_free(pid_ns_cachep, ns); |
| 102 | out: |
| 103 | return ERR_PTR(-ENOMEM); |
| 104 | } |
| 105 | |
| 106 | static void destroy_pid_namespace(struct pid_namespace *ns) |
| 107 | { |
| 108 | int i; |
| 109 | |
| 110 | for (i = 0; i < PIDMAP_ENTRIES; i++) |
| 111 | kfree(ns->pidmap[i].page); |
| 112 | kmem_cache_free(pid_ns_cachep, ns); |
| 113 | } |
| 114 | |
| 115 | struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns) |
| 116 | { |
| 117 | struct pid_namespace *new_ns; |
| 118 | |
| 119 | BUG_ON(!old_ns); |
| 120 | new_ns = get_pid_ns(old_ns); |
| 121 | if (!(flags & CLONE_NEWPID)) |
| 122 | goto out; |
| 123 | |
| 124 | new_ns = ERR_PTR(-EINVAL); |
| 125 | if (flags & CLONE_THREAD) |
| 126 | goto out_put; |
| 127 | |
| 128 | new_ns = create_pid_namespace(old_ns->level + 1); |
| 129 | if (!IS_ERR(new_ns)) |
| 130 | new_ns->parent = get_pid_ns(old_ns); |
| 131 | |
| 132 | out_put: |
| 133 | put_pid_ns(old_ns); |
| 134 | out: |
| 135 | return new_ns; |
| 136 | } |
| 137 | |
| 138 | void free_pid_ns(struct kref *kref) |
| 139 | { |
| 140 | struct pid_namespace *ns, *parent; |
| 141 | |
| 142 | ns = container_of(kref, struct pid_namespace, kref); |
| 143 | |
| 144 | parent = ns->parent; |
| 145 | destroy_pid_namespace(ns); |
| 146 | |
| 147 | if (parent != NULL) |
| 148 | put_pid_ns(parent); |
| 149 | } |
| 150 | |
| 151 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) |
| 152 | { |
| 153 | int nr; |
| 154 | int rc; |
| 155 | |
| 156 | /* |
| 157 | * The last thread in the cgroup-init thread group is terminating. |
| 158 | * Find remaining pid_ts in the namespace, signal and wait for them |
| 159 | * to exit. |
| 160 | * |
| 161 | * Note: This signals each threads in the namespace - even those that |
| 162 | * belong to the same thread group, To avoid this, we would have |
| 163 | * to walk the entire tasklist looking a processes in this |
| 164 | * namespace, but that could be unnecessarily expensive if the |
| 165 | * pid namespace has just a few processes. Or we need to |
| 166 | * maintain a tasklist for each pid namespace. |
| 167 | * |
| 168 | */ |
| 169 | read_lock(&tasklist_lock); |
| 170 | nr = next_pidmap(pid_ns, 1); |
| 171 | while (nr > 0) { |
| 172 | kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr); |
| 173 | nr = next_pidmap(pid_ns, nr); |
| 174 | } |
| 175 | read_unlock(&tasklist_lock); |
| 176 | |
| 177 | do { |
| 178 | clear_thread_flag(TIF_SIGPENDING); |
| 179 | rc = sys_wait4(-1, NULL, __WALL, NULL); |
| 180 | } while (rc != -ECHILD); |
| 181 | |
Pavel Emelyanov | 0b6b030 | 2008-07-25 01:48:47 -0700 | [diff] [blame] | 182 | acct_exit_ns(pid_ns); |
Pavel Emelyanov | 74bd59b | 2008-02-08 04:18:24 -0800 | [diff] [blame] | 183 | return; |
| 184 | } |
| 185 | |
| 186 | static __init int pid_namespaces_init(void) |
| 187 | { |
| 188 | pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); |
| 189 | return 0; |
| 190 | } |
| 191 | |
| 192 | __initcall(pid_namespaces_init); |