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Commit 741a2951 authored by JANAK DESAI's avatar JANAK DESAI Committed by Linus Torvalds
Browse files

[PATCH] unshare system call -v5: unshare namespace 



If the namespace structure is being shared, allocate a new one and copy
information from the current, shared, structure.

Signed-off-by: default avatarJanak Desai <janak@us.ibm.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 99d1419d

fs/namespace.c

+36 −20
Original line number Diff line number Diff line
@@ -1325,27 +1325,17 @@ long do_mount(char *dev_name, char *dir_name, char *type_page, 
	return retval;

}



int copy_namespace(int flags, struct task_struct *tsk)

/*

 * Allocate a new namespace structure and populate it with contents

 * copied from the namespace of the passed in task structure.

 */

struct namespace *dup_namespace(struct task_struct *tsk, struct fs_struct *fs)

{

	struct namespace *namespace = tsk->namespace;

	struct namespace *new_ns;

	struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;

	struct fs_struct *fs = tsk->fs;

	struct vfsmount *p, *q;



	if (!namespace)

		return 0;



	get_namespace(namespace);



	if (!(flags & CLONE_NEWNS))

		return 0;



	if (!capable(CAP_SYS_ADMIN)) {

		put_namespace(namespace);

		return -EPERM;

	}



	new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL);

	if (!new_ns)

		goto out;
@@ -1396,8 +1386,6 @@ int copy_namespace(int flags, struct task_struct *tsk) 
	}

	up_write(&namespace_sem);



	tsk->namespace = new_ns;



	if (rootmnt)

		mntput(rootmnt);

	if (pwdmnt)
@@ -1405,12 +1393,40 @@ int copy_namespace(int flags, struct task_struct *tsk) 
	if (altrootmnt)

		mntput(altrootmnt);



	put_namespace(namespace);

out:

	return new_ns;

}



int copy_namespace(int flags, struct task_struct *tsk)

{

	struct namespace *namespace = tsk->namespace;

	struct namespace *new_ns;

	int err = 0;



	if (!namespace)

		return 0;



	get_namespace(namespace);



	if (!(flags & CLONE_NEWNS))

		return 0;



	if (!capable(CAP_SYS_ADMIN)) {

		err = -EPERM;

		goto out;

	}



	new_ns = dup_namespace(tsk, tsk->fs);

	if (!new_ns) {

		err = -ENOMEM;

		goto out;

	}



	tsk->namespace = new_ns;



out:

	put_namespace(namespace);

	return -ENOMEM;

	return err;

}



asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name,

include/linux/namespace.h

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ struct namespace { 


extern int copy_namespace(int, struct task_struct *);

extern void __put_namespace(struct namespace *namespace);

extern struct namespace *dup_namespace(struct task_struct *, struct fs_struct *);



static inline void put_namespace(struct namespace *namespace)

{

kernel/fork.c

+11 −6
Original line number Diff line number Diff line
@@ -1388,16 +1388,21 @@ static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 
}



/*

 * Unsharing of namespace for tasks created without CLONE_NEWNS is not

 * supported yet

 * Unshare the namespace structure if it is being shared

 */

static int unshare_namespace(unsigned long unshare_flags, struct namespace **new_nsp)

static int unshare_namespace(unsigned long unshare_flags, struct namespace **new_nsp, struct fs_struct *new_fs)

{

	struct namespace *ns = current->namespace;



	if ((unshare_flags & CLONE_NEWNS) &&

	    (ns && atomic_read(&ns->count) > 1))

		return -EINVAL;

	    (ns && atomic_read(&ns->count) > 1)) {

		if (!capable(CAP_SYS_ADMIN))

			return -EPERM;



		*new_nsp = dup_namespace(current, new_fs ? new_fs : current->fs);

		if (!*new_nsp)

			return -ENOMEM;

	}



	return 0;

}
@@ -1482,7 +1487,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) 
		goto bad_unshare_out;

	if ((err = unshare_fs(unshare_flags, &new_fs)))

		goto bad_unshare_cleanup_thread;

	if ((err = unshare_namespace(unshare_flags, &new_ns)))

	if ((err = unshare_namespace(unshare_flags, &new_ns, new_fs)))

		goto bad_unshare_cleanup_fs;

	if ((err = unshare_sighand(unshare_flags, &new_sigh)))

		goto bad_unshare_cleanup_ns;