mqueue namespace: add struct mq_namespace

diff -puN /dev/null include/linux/mq_namespace.h
@@ -0,0 +1,67 @@
+#ifndef _LINUX_MQ_NAMESPACE_H
+#define _LINUX_MQ_NAMESPACE_H
+
+#include <linux/kref.h>
+
+struct vfsmount;
+
+struct mq_namespace {
+	struct kref	kref;
+	struct vfsmount *mnt;
+
+	unsigned int	queues_count;
+	unsigned int	queues_max;
+	unsigned int	msg_max;
+	unsigned int	msgsize_max;
+};
+
+extern struct mq_namespace init_mq_ns;
+
+/* default values */
+#define DFLT_QUEUESMAX	256	/* max number of message queues */
+#define DFLT_MSGMAX 	10	/* max number of messages in each queue */
+#define HARD_MSGMAX 	(131072/sizeof(void *))
+#define DFLT_MSGSIZEMAX 8192	/* max message size */
+
+#ifdef CONFIG_POSIX_MQUEUE
+#define INIT_MQ_NS(ns)		.ns		= &init_mq_ns,
+#else
+#define INIT_MQ_NS(ns)
+#endif
+
+#if defined(CONFIG_POSIX_MQUEUE) && defined(CONFIG_MQ_NS)
+static inline struct mq_namespace *get_mq_ns(struct mq_namespace *ns)
+{
+	if (ns)
+		kref_get(&ns->kref);
+	return ns;
+}
+
+extern struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
+				struct mq_namespace *old_ns);
+extern void free_mq_ns(struct kref *kref);
+
+static inline void put_mq_ns(struct mq_namespace *ns)
+{
+	if (ns)
+		kref_put(&ns->kref, free_mq_ns);
+}
+
+#else
+
+static inline struct mq_namespace *get_mq_ns(struct mq_namespace *ns)
+{
+	return ns;
+}
+
+static inline struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
+					struct mq_namespace *old_ns)
+{
+	return old_ns;
+}
+
+static inline void put_mq_ns(struct mq_namespace *ns) { }
+
+#endif /* CONFIG_POSIX_MQUEUE */
+
+#endif /* _LINUX_MQ_H */

diff -puN /dev/null ipc/mq_namespace.c
@@ -0,0 +1,23 @@
+/*
+ *  Copyright (C) 2007 IBM Corporation
+ *
+ *  Author: Cedric Le Goater <clg-NmTC/[email protected]>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License as
+ *  published by the Free Software Foundation, version 2 of the
+ *  License.
+ */
+
+#include <linux/mq_namespace.h>
+
+struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
+				struct mq_namespace *old_ns)
+{
+	BUG_ON(!old_ns);
+	return get_mq_ns(old_ns);
+}
+
+void free_mq_ns(struct kref *kref)
+{
+}

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diff -puN include/linux/init_task.h~mq_namespace-add-mq_namespace-to-nsproxy include/linux/init_task.h
@@ -10,6 +10,7 @@
 #include <linux/user_namespace.h>
 #include <linux/securebits.h>
 #include <net/net_namespace.h>
+#include <linux/mq_namespace.h>
 
 extern struct files_struct init_files;
 

@@ -58,6 +59,7 @@ extern struct nsproxy init_nsproxy;
 	INIT_NET_NS(net_ns)                                             \
 	INIT_IPC_NS(ipc_ns)						\
 	.user_ns	= &init_user_ns,				\
+	INIT_MQ_NS(mq_ns)						\
 }
 
 #define INIT_SIGHAND(sighand) {						\

diff -puN include/linux/mq_namespace.h~mq_namespace-add-mq_namespace-to-nsproxy include/linux/mq_namespace.h
@@ -2,6 +2,7 @@
 #define _LINUX_MQ_NAMESPACE_H
 
 #include <linux/kref.h>
+#include <linux/err.h>
 
 struct vfsmount;
 

diff -puN include/linux/nsproxy.h~mq_namespace-add-mq_namespace-to-nsproxy include/linux/nsproxy.h
@@ -8,6 +8,7 @@ struct mnt_namespace;
 struct uts_namespace;
 struct ipc_namespace;
 struct pid_namespace;
+struct mq_namespace;
 
 /*
  * A structure to contain pointers to all per-process

@@ -29,6 +30,7 @@ struct nsproxy {
 	struct pid_namespace *pid_ns;
 	struct user_namespace *user_ns;
 	struct net 	     *net_ns;
+	struct mq_namespace *mq_ns;
 };
 extern struct nsproxy init_nsproxy;
 

diff -puN ipc/mq_namespace.c~mq_namespace-add-mq_namespace-to-nsproxy ipc/mq_namespace.c
@@ -10,14 +10,48 @@
  */
 
 #include <linux/mq_namespace.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+
+static struct mq_namespace *clone_mq_ns(struct mq_namespace *old_ns)
+{
+	struct mq_namespace *mq_ns;
+
+	mq_ns = kmalloc(sizeof(struct mq_namespace), GFP_KERNEL);
+	if (!mq_ns)
+		return ERR_PTR(-ENOMEM);
+
+	kref_init(&mq_ns->kref);
+	mq_ns->queues_count	= 0;
+	mq_ns->queues_max	= DFLT_QUEUESMAX;
+	mq_ns->msg_max		= DFLT_MSGMAX;
+	mq_ns->msgsize_max	= DFLT_MSGSIZEMAX;
+	mq_ns->mnt		= NULL;
+	return mq_ns;
+}
 
 struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
 				struct mq_namespace *old_ns)
 {
+	struct mq_namespace *mq_ns;
+
 	BUG_ON(!old_ns);
-	return get_mq_ns(old_ns);
+	get_mq_ns(old_ns);
+
+	if (!(clone_flags & CLONE_NEWIPC))
+		return old_ns;
+
+	mq_ns = clone_mq_ns(old_ns);
+
+	put_mq_ns(old_ns);
+	return mq_ns;
 }
 
 void free_mq_ns(struct kref *kref)
 {
+	struct mq_namespace *ns;
+
+	ns = container_of(kref, struct mq_namespace, kref);
+	kfree(ns);
 }

diff -puN kernel/nsproxy.c~mq_namespace-add-mq_namespace-to-nsproxy kernel/nsproxy.c
@@ -93,8 +93,17 @@ static struct nsproxy *create_new_namesp
 		goto out_net;
 	}
 
+	new_nsp->mq_ns = copy_mq_ns(flags, tsk->nsproxy->mq_ns);
+	if (IS_ERR(new_nsp->mq_ns)) {
+		err = PTR_ERR(new_nsp->mq_ns);
+		goto out_mq;
+	}
+
 	return new_nsp;
 
+out_mq:
+	if (new_nsp->net_ns)
+		put_net(new_nsp->net_ns);
 out_net:
 	if (new_nsp->user_ns)
 		put_user_ns(new_nsp->user_ns);

@@ -182,6 +191,8 @@ void free_nsproxy(struct nsproxy *ns)
 		put_pid_ns(ns->pid_ns);
 	if (ns->user_ns)
 		put_user_ns(ns->user_ns);
+	if (ns->mq_ns)
+		put_mq_ns(ns->mq_ns);
 	put_net(ns->net_ns);
 	kmem_cache_free(nsproxy_cachep, ns);
 }

diff -puN fs/super.c~add-get_sb_single_ns-helper fs/super.c
@@ -882,6 +882,43 @@ int get_sb_single(struct file_system_typ
 
 EXPORT_SYMBOL(get_sb_single);
 
+static int compare_sb_single_ns(struct super_block *sb, void *data)
+{
+	return sb->s_fs_info == data;
+}
+
+static int set_sb_single_ns(struct super_block *sb, void *data)
+{
+	sb->s_fs_info = data;
+	return set_anon_super(sb, data);
+}
+
+int get_sb_single_ns(struct file_system_type *fs_type,
+	int flags, void *data,
+	int (*fill_super)(struct super_block *, void *, int),
+	struct vfsmount *mnt)
+{
+	struct super_block *s;
+	int error;
+
+	s = sget(fs_type, compare_sb_single_ns, set_sb_single_ns, data);
+	if (IS_ERR(s))
+		return PTR_ERR(s);
+	if (!s->s_root) {
+		s->s_flags = flags;
+		error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
+		if (error) {
+			up_write(&s->s_umount);
+			deactivate_super(s);
+			return error;
+		}
+		s->s_flags |= MS_ACTIVE;
+	}
+	do_remount_sb(s, flags, data, 0);
+	return simple_set_mnt(mnt, s);
+}
+EXPORT_SYMBOL(get_sb_single_ns);
+
 struct vfsmount *
 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
 {

diff -puN include/linux/fs.h~add-get_sb_single_ns-helper include/linux/fs.h
@@ -1502,6 +1502,10 @@ extern int get_sb_nodev(struct file_syst
 	int flags, void *data,
 	int (*fill_super)(struct super_block *, void *, int),
 	struct vfsmount *mnt);
+extern int get_sb_single_ns(struct file_system_type *fs_type,
+	int flags, void *data,
+	int (*fill_super)(struct super_block *, void *, int),
+	struct vfsmount *mnt);
 void generic_shutdown_super(struct super_block *sb);
 void kill_block_super(struct super_block *sb);
 void kill_anon_super(struct super_block *sb);

diff -puN include/linux/mq_namespace.h~mq_namespace-use-mq_namespace include/linux/mq_namespace.h
@@ -3,6 +3,7 @@
 
 #include <linux/kref.h>
 #include <linux/err.h>
+#include <linux/fs.h>
 
 struct vfsmount;
 

@@ -17,6 +18,7 @@ struct mq_namespace {
 };
 
 extern struct mq_namespace init_mq_ns;
+extern struct file_system_type mqueue_fs_type;
 
 /* default values */
 #define DFLT_QUEUESMAX	256	/* max number of message queues */

diff -puN ipc/mq_namespace.c~mq_namespace-use-mq_namespace ipc/mq_namespace.c
@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/err.h>
+#include <linux/mount.h>
 
 static struct mq_namespace *clone_mq_ns(struct mq_namespace *old_ns)
 {

@@ -27,7 +28,12 @@ static struct mq_namespace *clone_mq_ns(
 	mq_ns->queues_max	= DFLT_QUEUESMAX;
 	mq_ns->msg_max		= DFLT_MSGMAX;
 	mq_ns->msgsize_max	= DFLT_MSGSIZEMAX;
-	mq_ns->mnt		= NULL;
+	mq_ns->mnt		= kern_mount_data(&mqueue_fs_type, mq_ns);
+	if (IS_ERR(mq_ns->mnt)) {
+		void *error = mq_ns->mnt;
+		kfree(mq_ns);
+		return error;
+	}
 	return mq_ns;
 }
 

@@ -53,5 +59,7 @@ void free_mq_ns(struct kref *kref)
 	struct mq_namespace *ns;
 
 	ns = container_of(kref, struct mq_namespace, kref);
+	ns->mnt->mnt_sb->s_fs_info = NULL;
+	mntput(ns->mnt);
 	kfree(ns);
 }

diff -puN ipc/mqueue.c~mq_namespace-use-mq_namespace ipc/mqueue.c
@@ -204,7 +204,10 @@ static int mqueue_get_sb(struct file_sys
 			 int flags, const char *dev_name,
 			 void *data, struct vfsmount *mnt)
 {
-	return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
+	if (!(flags & MS_KERNMOUNT))
+		data = current->nsproxy->mq_ns;
+
+	return get_sb_single_ns(fs_type, flags, data, mqueue_fill_super, mnt);
 }
 
 static void init_once(struct kmem_cache *cachep, void *foo)

@@ -235,7 +238,7 @@ static void mqueue_delete_inode(struct i
 	struct user_struct *user;
 	unsigned long mq_bytes;
 	int i;
-	struct mq_namespace *mq_ns = &init_mq_ns;
+	struct mq_namespace *mq_ns = inode->i_sb->s_fs_info;
 
 	if (S_ISDIR(inode->i_mode)) {
 		clear_inode(inode);

@@ -256,7 +259,8 @@ static void mqueue_delete_inode(struct i
 	if (user) {
 		spin_lock(&mq_lock);
 		user->mq_bytes -= mq_bytes;
-		mq_ns->queues_count--;
+		if (mq_ns)
+			mq_ns->queues_count--;
 		spin_unlock(&mq_lock);
 		free_uid(user);
 	}

@@ -268,7 +272,15 @@ static int mqueue_create(struct inode *d
 	struct inode *inode;
 	struct mq_attr *attr = dentry->d_fsdata;
 	int error;
-	struct mq_namespace *mq_ns = &init_mq_ns;
+	struct mq_namespace *mq_ns = dir->i_sb->s_fs_info;
+
+	/*
+	 * There is a race on sb->s_fs_info with free_mq_ns() but it
+	 * shouldn't be an issue as we are only interested in
+	 * current->nsproxy->mq_ns which is valid.
+	 */
+	if (mq_ns != current->nsproxy->mq_ns)
+		return -EACCES;
 
 	spin_lock(&mq_lock);
 	if (mq_ns->queues_count >= mq_ns->queues_max &&

@@ -301,6 +313,15 @@ out_lock:
 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 {
   	struct inode *inode = dentry->d_inode;
+	struct mq_namespace *mq_ns = dir->i_sb->s_fs_info;
+
+	/*
+	 * There is a race on sb->s_fs_info with free_mq_ns() but it
+	 * shouldn't be an issue as we are only interested in
+	 * current->nsproxy->mq_ns which is valid.
+	 */
+	if (mq_ns != current->nsproxy->mq_ns)
+		return -EACCES;
 
 	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 	dir->i_size -= DIRENT_SIZE;

@@ -670,7 +691,7 @@ asmlinkage long sys_mq_open(const char _
 	struct file *filp;
 	char *name;
 	int fd, error;
-	struct mq_namespace *mq_ns = &init_mq_ns;
+	struct mq_namespace *mq_ns = current->nsproxy->mq_ns;
 
 	error = audit_mq_open(oflag, mode, u_attr);
 	if (error != 0)

@@ -738,7 +759,7 @@ asmlinkage long sys_mq_unlink(const char
 	char *name;
 	struct dentry *dentry;
 	struct inode *inode = NULL;
-	struct mq_namespace *mq_ns = &init_mq_ns;
+	struct mq_namespace *mq_ns = current->nsproxy->mq_ns;
 
 	name = getname(u_name);
 	if (IS_ERR(name))

@@ -1203,7 +1224,7 @@ static struct super_operations mqueue_su
 	.drop_inode = generic_delete_inode,
 };
 
-static struct file_system_type mqueue_fs_type = {
+struct file_system_type mqueue_fs_type = {
 	.name = "mqueue",
 	.get_sb = mqueue_get_sb,
 	.kill_sb = kill_litter_super,

@@ -1280,7 +1301,7 @@ static int __init init_mqueue_fs(void)
 	if (error)
 		goto out_sysctl;
 
-	init_mq_ns.mnt = kern_mount(&mqueue_fs_type);
+	init_mq_ns.mnt = kern_mount_data(&mqueue_fs_type, &init_mq_ns);
 	if (IS_ERR(init_mq_ns.mnt)) {
 		error = PTR_ERR(init_mq_ns.mnt);
 		goto out_filesystem;

diff -puN include/linux/mq_namespace.h~mq_namespace-fix-sysctl include/linux/mq_namespace.h
@@ -67,4 +67,14 @@ static inline void put_mq_ns(struct mq_n
 
 #endif /* CONFIG_POSIX_MQUEUE */
 
+#ifdef CONFIG_POSIX_MQUEUE_SYSCTL
+struct ctl_table_header;
+extern struct ctl_table_header *mq_register_sysctl_table(void);
+#else
+static inline struct ctl_table_header *mq_register_sysctl_table(void)
+{
+	return NULL;
+}
+#endif /* CONFIG_POSIX_MQUEUE_SYSCTL */
+
 #endif /* _LINUX_MQ_H */

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