Commit 771b1371 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

vfs: Add a user namespace reference from struct mnt_namespace 



This will allow for support for unprivileged mounts in a new user namespace.

Acked-by: default avatar"Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 8823c079

fs/mount.h

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ struct mnt_namespace { 
	atomic_t		count;

	struct mount *	root;

	struct list_head	list;

	struct user_namespace	*user_ns;

	u64			seq;	/* Sequence number to prevent loops */

	wait_queue_head_t poll;

	int event;

fs/namespace.c

+16 −8
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/export.h>

#include <linux/capability.h>

#include <linux/mnt_namespace.h>

#include <linux/user_namespace.h>

#include <linux/namei.h>

#include <linux/security.h>

#include <linux/idr.h>
@@ -2286,6 +2287,12 @@ long do_mount(const char *dev_name, const char *dir_name, 
	return retval;

}



static void free_mnt_ns(struct mnt_namespace *ns)

{

	put_user_ns(ns->user_ns);

	kfree(ns);

}



/*

 * Assign a sequence number so we can detect when we attempt to bind

 * mount a reference to an older mount namespace into the current
@@ -2295,7 +2302,7 @@ long do_mount(const char *dev_name, const char *dir_name, 
 */

static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);



static struct mnt_namespace *alloc_mnt_ns(void)

static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)

{

	struct mnt_namespace *new_ns;
@@ -2308,6 +2315,7 @@ static struct mnt_namespace *alloc_mnt_ns(void) 
	INIT_LIST_HEAD(&new_ns->list);

	init_waitqueue_head(&new_ns->poll);

	new_ns->event = 0;

	new_ns->user_ns = get_user_ns(user_ns);

	return new_ns;

}
@@ -2316,7 +2324,7 @@ static struct mnt_namespace *alloc_mnt_ns(void) 
 * copied from the namespace of the passed in task structure.

 */

static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,

		struct fs_struct *fs)

		struct user_namespace *user_ns, struct fs_struct *fs)

{

	struct mnt_namespace *new_ns;

	struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
@@ -2324,7 +2332,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, 
	struct mount *old = mnt_ns->root;

	struct mount *new;



	new_ns = alloc_mnt_ns();

	new_ns = alloc_mnt_ns(user_ns);

	if (IS_ERR(new_ns))

		return new_ns;
@@ -2333,7 +2341,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, 
	new = copy_tree(old, old->mnt.mnt_root, CL_COPY_ALL | CL_EXPIRE);

	if (IS_ERR(new)) {

		up_write(&namespace_sem);

		kfree(new_ns);

		free_mnt_ns(new_ns);

		return ERR_CAST(new);

	}

	new_ns->root = new;
@@ -2374,7 +2382,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, 
}



struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,

		struct fs_struct *new_fs)

		struct user_namespace *user_ns, struct fs_struct *new_fs)

{

	struct mnt_namespace *new_ns;
@@ -2384,7 +2392,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, 
	if (!(flags & CLONE_NEWNS))

		return ns;



	new_ns = dup_mnt_ns(ns, new_fs);

	new_ns = dup_mnt_ns(ns, user_ns, new_fs);



	put_mnt_ns(ns);

	return new_ns;
@@ -2396,7 +2404,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, 
 */

static struct mnt_namespace *create_mnt_ns(struct vfsmount *m)

{

	struct mnt_namespace *new_ns = alloc_mnt_ns();

	struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns);

	if (!IS_ERR(new_ns)) {

		struct mount *mnt = real_mount(m);

		mnt->mnt_ns = new_ns;
@@ -2682,7 +2690,7 @@ void put_mnt_ns(struct mnt_namespace *ns) 
	br_write_unlock(&vfsmount_lock);

	up_write(&namespace_sem);

	release_mounts(&umount_list);

	kfree(ns);

	free_mnt_ns(ns);

}



struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)

include/linux/mnt_namespace.h

+2 −1
Original line number Diff line number Diff line
@@ -4,9 +4,10 @@ 


struct mnt_namespace;

struct fs_struct;

struct user_namespace;



extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *,

		struct fs_struct *);

		struct user_namespace *, struct fs_struct *);

extern void put_mnt_ns(struct mnt_namespace *ns);



extern const struct file_operations proc_mounts_operations;

kernel/nsproxy.c

+1 −1
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ static struct nsproxy *create_new_namespaces(unsigned long flags, 
	if (!new_nsp)

		return ERR_PTR(-ENOMEM);



	new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);

	new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, task_cred_xxx(tsk, user_ns), new_fs);

	if (IS_ERR(new_nsp->mnt_ns)) {

		err = PTR_ERR(new_nsp->mnt_ns);

		goto out_ns;