[PATCH] IPC namespace - utils

This patch adds basic IPC namespace functionality to
IPC utils:
- init_ipc_ns
- copy/clone/unshare/free IPC ns
- /proc preparations
Signed-off-by: NPavel Emelianov <xemul@openvz.org>
Signed-off-by: NKirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/linux/init_task.h

@@ -6,6 +6,7 @@
 #include <linux/irqflags.h>
 #include <linux/utsname.h>
 #include <linux/lockdep.h>
+#include <linux/ipc.h>
 
 #define INIT_FDTABLE \
 {							\
@@ -74,8 +75,8 @@ extern struct nsproxy init_nsproxy;
 	.count		= ATOMIC_INIT(1),				\
 	.nslock		= SPIN_LOCK_UNLOCKED,				\
 	.uts_ns		= &init_uts_ns,					\
-	.ipc_ns		= &init_ipc_ns,					\
 	.namespace	= NULL,						\
+	INIT_IPC_NS(ipc_ns)						\
 }
 
 #define INIT_SIGHAND(sighand) {						\

include/linux/ipc.h

@@ -88,20 +88,38 @@ struct ipc_namespace {
 };
 
 extern struct ipc_namespace init_ipc_ns;
+
+#ifdef CONFIG_SYSVIPC
+#define INIT_IPC_NS(ns)		.ns		= &init_ipc_ns,
+#else
+#define INIT_IPC_NS(ns)
+#endif
+
+#ifdef CONFIG_IPC_NS
 extern void free_ipc_ns(struct kref *kref);
 extern int copy_ipcs(unsigned long flags, struct task_struct *tsk);
 extern int unshare_ipcs(unsigned long flags, struct ipc_namespace **ns);
+#else
+static inline int copy_ipcs(unsigned long flags, struct task_struct *tsk)
+{
+	return 0;
+}
+#endif
 
 static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
 {
+#ifdef CONFIG_IPC_NS
 	if (ns)
 		kref_get(&ns->kref);
+#endif
 	return ns;
 }
 
 static inline void put_ipc_ns(struct ipc_namespace *ns)
 {
+#ifdef CONFIG_IPC_NS
 	kref_put(&ns->kref, free_ipc_ns);
+#endif
 }
 
 #endif /* __KERNEL__ */

ipc/util.c

@@ -12,6 +12,9 @@
  *            Mingming Cao <cmm@us.ibm.com>
  * Mar 2006 - support for audit of ipc object properties
  *            Dustin Kirkland <dustin.kirkland@us.ibm.com>
+ * Jun 2006 - namespaces ssupport
+ *            OpenVZ, SWsoft Inc.
+ *            Pavel Emelianov <xemul@openvz.org>
  */
 
 #include <linux/mm.h>
@@ -29,6 +32,7 @@
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
 #include <linux/audit.h>
+#include <linux/nsproxy.h>
 
 #include <asm/unistd.h>
 
@@ -37,10 +41,111 @@
 struct ipc_proc_iface {
 	const char *path;
 	const char *header;
-	struct ipc_ids *ids;
+	int ids;
 	int (*show)(struct seq_file *, void *);
 };
 
+struct ipc_namespace init_ipc_ns = {
+	.kref = {
+		.refcount	= ATOMIC_INIT(2),
+	},
+};
+
+#ifdef CONFIG_IPC_NS
+static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
+{
+	int err;
+	struct ipc_namespace *ns;
+
+	err = -ENOMEM;
+	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
+	if (ns == NULL)
+		goto err_mem;
+
+	err = sem_init_ns(ns);
+	if (err)
+		goto err_sem;
+	err = msg_init_ns(ns);
+	if (err)
+		goto err_msg;
+	err = shm_init_ns(ns);
+	if (err)
+		goto err_shm;
+
+	kref_init(&ns->kref);
+	return ns;
+
+err_shm:
+	msg_exit_ns(ns);
+err_msg:
+	sem_exit_ns(ns);
+err_sem:
+	kfree(ns);
+err_mem:
+	return ERR_PTR(err);
+}
+
+int unshare_ipcs(unsigned long unshare_flags, struct ipc_namespace **new_ipc)
+{
+	struct ipc_namespace *new;
+
+	if (unshare_flags & CLONE_NEWIPC) {
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+
+		new = clone_ipc_ns(current->nsproxy->ipc_ns);
+		if (IS_ERR(new))
+			return PTR_ERR(new);
+
+		*new_ipc = new;
+	}
+
+	return 0;
+}
+
+int copy_ipcs(unsigned long flags, struct task_struct *tsk)
+{
+	struct ipc_namespace *old_ns = tsk->nsproxy->ipc_ns;
+	struct ipc_namespace *new_ns;
+	int err = 0;
+
+	if (!old_ns)
+		return 0;
+
+	get_ipc_ns(old_ns);
+
+	if (!(flags & CLONE_NEWIPC))
+		return 0;
+
+	if (!capable(CAP_SYS_ADMIN)) {
+		err = -EPERM;
+		goto out;
+	}
+
+	new_ns = clone_ipc_ns(old_ns);
+	if (!new_ns) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	tsk->nsproxy->ipc_ns = new_ns;
+out:
+	put_ipc_ns(old_ns);
+	return err;
+}
+
+void free_ipc_ns(struct kref *kref)
+{
+	struct ipc_namespace *ns;
+
+	ns = container_of(kref, struct ipc_namespace, kref);
+	sem_exit_ns(ns);
+	msg_exit_ns(ns);
+	shm_exit_ns(ns);
+	kfree(ns);
+}
+#endif
+
 /**
  *	ipc_init	-	initialise IPC subsystem
  *
@@ -67,7 +172,7 @@ __initcall(ipc_init);
  *	array itself. 
  */
  
-void __init ipc_init_ids(struct ipc_ids* ids, int size)
+void __ipc_init ipc_init_ids(struct ipc_ids* ids, int size)
 {
 	int i;
 
@@ -110,8 +215,7 @@ static struct file_operations sysvipc_proc_fops;
  *	@show: show routine.
  */
 void __init ipc_init_proc_interface(const char *path, const char *header,
-				    struct ipc_ids *ids,
-				    int (*show)(struct seq_file *, void *))
+		int ids, int (*show)(struct seq_file *, void *))
 {
 	struct proc_dir_entry *pde;
 	struct ipc_proc_iface *iface;
@@ -635,6 +739,9 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 	struct ipc_proc_iface *iface = s->private;
 	struct kern_ipc_perm *ipc = it;
 	loff_t p;
+	struct ipc_ids *ids;
+
+	ids = current->nsproxy->ipc_ns->ids[iface->ids];
 
 	/* If we had an ipc id locked before, unlock it */
 	if (ipc && ipc != SEQ_START_TOKEN)
@@ -644,8 +751,8 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 	 * p = *pos - 1 (because id 0 starts at position 1)
 	 *          + 1 (because we increment the position by one)
 	 */
-	for (p = *pos; p <= iface->ids->max_id; p++) {
-		if ((ipc = ipc_lock(iface->ids, p)) != NULL) {
+	for (p = *pos; p <= ids->max_id; p++) {
+		if ((ipc = ipc_lock(ids, p)) != NULL) {
 			*pos = p + 1;
 			return ipc;
 		}
@@ -664,12 +771,15 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 	struct ipc_proc_iface *iface = s->private;
 	struct kern_ipc_perm *ipc;
 	loff_t p;
+	struct ipc_ids *ids;
+
+	ids = current->nsproxy->ipc_ns->ids[iface->ids];
 
 	/*
 	 * Take the lock - this will be released by the corresponding
 	 * call to stop().
 	 */
-	mutex_lock(&iface->ids->mutex);
+	mutex_lock(&ids->mutex);
 
 	/* pos < 0 is invalid */
 	if (*pos < 0)
@@ -680,8 +790,8 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 		return SEQ_START_TOKEN;
 
 	/* Find the (pos-1)th ipc */
-	for (p = *pos - 1; p <= iface->ids->max_id; p++) {
-		if ((ipc = ipc_lock(iface->ids, p)) != NULL) {
+	for (p = *pos - 1; p <= ids->max_id; p++) {
+		if ((ipc = ipc_lock(ids, p)) != NULL) {
 			*pos = p + 1;
 			return ipc;
 		}
@@ -693,13 +803,15 @@ static void sysvipc_proc_stop(struct seq_file *s, void *it)
 {
 	struct kern_ipc_perm *ipc = it;
 	struct ipc_proc_iface *iface = s->private;
+	struct ipc_ids *ids;
 
 	/* If we had a locked segment, release it */
 	if (ipc && ipc != SEQ_START_TOKEN)
 		ipc_unlock(ipc);
 
+	ids = current->nsproxy->ipc_ns->ids[iface->ids];
 	/* Release the lock we took in start() */
-	mutex_unlock(&iface->ids->mutex);
+	mutex_unlock(&ids->mutex);
 }
 
 static int sysvipc_proc_show(struct seq_file *s, void *it)

ipc/util.h

@@ -3,6 +3,8 @@
  * Copyright (C) 1999 Christoph Rohland
  *
  * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
+ * namespaces support.      2006 OpenVZ, SWsoft Inc.
+ *                               Pavel Emelianov <xemul@openvz.org>
  */
 
 #ifndef _IPC_UTIL_H
@@ -15,6 +17,14 @@ void sem_init (void);
 void msg_init (void);
 void shm_init (void);
 
+int sem_init_ns(struct ipc_namespace *ns);
+int msg_init_ns(struct ipc_namespace *ns);
+int shm_init_ns(struct ipc_namespace *ns);
+
+void sem_exit_ns(struct ipc_namespace *ns);
+void msg_exit_ns(struct ipc_namespace *ns);
+void shm_exit_ns(struct ipc_namespace *ns);
+
 struct ipc_id_ary {
 	int size;
 	struct kern_ipc_perm *p[0];
@@ -31,15 +41,23 @@ struct ipc_ids {
 };
 
 struct seq_file;
-void __init ipc_init_ids(struct ipc_ids* ids, int size);
+#ifdef CONFIG_IPC_NS
+#define __ipc_init
+#else
+#define __ipc_init	__init
+#endif
+void __ipc_init ipc_init_ids(struct ipc_ids *ids, int size);
 #ifdef CONFIG_PROC_FS
 void __init ipc_init_proc_interface(const char *path, const char *header,
-				    struct ipc_ids *ids,
-				    int (*show)(struct seq_file *, void *));
+		int ids, int (*show)(struct seq_file *, void *));
 #else
 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
 #endif
 
+#define IPC_SEM_IDS	0
+#define IPC_MSG_IDS	1
+#define IPC_SHM_IDS	2
+
 /* must be called with ids->mutex acquired.*/
 int ipc_findkey(struct ipc_ids* ids, key_t key);
 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size);

kernel/fork.c

@@ -1589,6 +1589,16 @@ static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **n
 	return 0;
 }
 
+#ifndef CONFIG_IPC_NS
+static inline int unshare_ipcs(unsigned long flags, struct ipc_namespace **ns)
+{
+	if (flags & CLONE_NEWIPC)
+		return -EINVAL;
+
+	return 0;
+}
+#endif
+
 /*
  * unshare allows a process to 'unshare' part of the process
  * context which was originally shared using clone.  copy_*