1 /* 2 * linux/ipc/namespace.c 3 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc. 4 */ 5 6 #include <linux/ipc.h> 7 #include <linux/msg.h> 8 #include <linux/ipc_namespace.h> 9 #include <linux/rcupdate.h> 10 #include <linux/nsproxy.h> 11 #include <linux/slab.h> 12 #include <linux/fs.h> 13 #include <linux/mount.h> 14 #include <linux/user_namespace.h> 15 #include <linux/proc_ns.h> 16 17 #include "util.h" 18 19 static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, 20 struct ipc_namespace *old_ns) 21 { 22 struct ipc_namespace *ns; 23 int err; 24 25 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL); 26 if (ns == NULL) 27 return ERR_PTR(-ENOMEM); 28 29 err = proc_alloc_inum(&ns->proc_inum); 30 if (err) { 31 kfree(ns); 32 return ERR_PTR(err); 33 } 34 35 atomic_set(&ns->count, 1); 36 err = mq_init_ns(ns); 37 if (err) { 38 proc_free_inum(ns->proc_inum); 39 kfree(ns); 40 return ERR_PTR(err); 41 } 42 atomic_inc(&nr_ipc_ns); 43 44 sem_init_ns(ns); 45 msg_init_ns(ns); 46 shm_init_ns(ns); 47 48 ns->user_ns = get_user_ns(user_ns); 49 50 return ns; 51 } 52 53 struct ipc_namespace *copy_ipcs(unsigned long flags, 54 struct user_namespace *user_ns, struct ipc_namespace *ns) 55 { 56 if (!(flags & CLONE_NEWIPC)) 57 return get_ipc_ns(ns); 58 return create_ipc_ns(user_ns, ns); 59 } 60 61 /* 62 * free_ipcs - free all ipcs of one type 63 * @ns: the namespace to remove the ipcs from 64 * @ids: the table of ipcs to free 65 * @free: the function called to free each individual ipc 66 * 67 * Called for each kind of ipc when an ipc_namespace exits. 68 */ 69 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, 70 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)) 71 { 72 struct kern_ipc_perm *perm; 73 int next_id; 74 int total, in_use; 75 76 down_write(&ids->rwsem); 77 78 in_use = ids->in_use; 79 80 for (total = 0, next_id = 0; total < in_use; next_id++) { 81 perm = idr_find(&ids->ipcs_idr, next_id); 82 if (perm == NULL) 83 continue; 84 rcu_read_lock(); 85 ipc_lock_object(perm); 86 free(ns, perm); 87 total++; 88 } 89 up_write(&ids->rwsem); 90 } 91 92 static void free_ipc_ns(struct ipc_namespace *ns) 93 { 94 sem_exit_ns(ns); 95 msg_exit_ns(ns); 96 shm_exit_ns(ns); 97 atomic_dec(&nr_ipc_ns); 98 99 put_user_ns(ns->user_ns); 100 proc_free_inum(ns->proc_inum); 101 kfree(ns); 102 } 103 104 /* 105 * put_ipc_ns - drop a reference to an ipc namespace. 106 * @ns: the namespace to put 107 * 108 * If this is the last task in the namespace exiting, and 109 * it is dropping the refcount to 0, then it can race with 110 * a task in another ipc namespace but in a mounts namespace 111 * which has this ipcns's mqueuefs mounted, doing some action 112 * with one of the mqueuefs files. That can raise the refcount. 113 * So dropping the refcount, and raising the refcount when 114 * accessing it through the VFS, are protected with mq_lock. 115 * 116 * (Clearly, a task raising the refcount on its own ipc_ns 117 * needn't take mq_lock since it can't race with the last task 118 * in the ipcns exiting). 119 */ 120 void put_ipc_ns(struct ipc_namespace *ns) 121 { 122 if (atomic_dec_and_lock(&ns->count, &mq_lock)) { 123 mq_clear_sbinfo(ns); 124 spin_unlock(&mq_lock); 125 mq_put_mnt(ns); 126 free_ipc_ns(ns); 127 } 128 } 129 130 static void *ipcns_get(struct task_struct *task) 131 { 132 struct ipc_namespace *ns = NULL; 133 struct nsproxy *nsproxy; 134 135 task_lock(task); 136 nsproxy = task->nsproxy; 137 if (nsproxy) 138 ns = get_ipc_ns(nsproxy->ipc_ns); 139 task_unlock(task); 140 141 return ns; 142 } 143 144 static void ipcns_put(void *ns) 145 { 146 return put_ipc_ns(ns); 147 } 148 149 static int ipcns_install(struct nsproxy *nsproxy, void *new) 150 { 151 struct ipc_namespace *ns = new; 152 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) || 153 !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) 154 return -EPERM; 155 156 /* Ditch state from the old ipc namespace */ 157 exit_sem(current); 158 put_ipc_ns(nsproxy->ipc_ns); 159 nsproxy->ipc_ns = get_ipc_ns(ns); 160 return 0; 161 } 162 163 static unsigned int ipcns_inum(void *vp) 164 { 165 struct ipc_namespace *ns = vp; 166 167 return ns->proc_inum; 168 } 169 170 const struct proc_ns_operations ipcns_operations = { 171 .name = "ipc", 172 .type = CLONE_NEWIPC, 173 .get = ipcns_get, 174 .put = ipcns_put, 175 .install = ipcns_install, 176 .inum = ipcns_inum, 177 }; 178