#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>
#include <linux/fs_struct.h> /* get_fs_root et.al. */
#include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
#include <linux/uaccess.h>
+#include <linux/proc_fs.h>
#include "pnode.h"
#include "internal.h"
* incremented count after it has set MNT_WRITE_HOLD.
*/
smp_mb();
- while (mnt->mnt.mnt_flags & MNT_WRITE_HOLD)
+ while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
cpu_relax();
/*
* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
if (!mnt)
return ERR_PTR(-ENOMEM);
- if (flag & (CL_SLAVE | CL_PRIVATE))
+ if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE))
mnt->mnt_group_id = 0; /* not a peer of original */
else
mnt->mnt_group_id = old->mnt_group_id;
list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
br_write_unlock(&vfsmount_lock);
- if (flag & CL_SLAVE) {
+ if ((flag & CL_SLAVE) ||
+ ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
list_add(&mnt->mnt_slave, &old->mnt_slave_list);
mnt->mnt_master = old;
CLEAR_MNT_SHARED(mnt);
goto dput_and_out;
retval = -EPERM;
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(mnt->mnt_ns->user_ns, CAP_SYS_ADMIN))
goto dput_and_out;
retval = do_umount(mnt, flags);
static int mount_is_safe(struct path *path)
{
- if (capable(CAP_SYS_ADMIN))
+ if (ns_capable(real_mount(path->mnt)->mnt_ns->user_ns, CAP_SYS_ADMIN))
return 0;
return -EPERM;
#ifdef notyet
#endif
}
+static bool mnt_ns_loop(struct path *path)
+{
+ /* Could bind mounting the mount namespace inode cause a
+ * mount namespace loop?
+ */
+ struct inode *inode = path->dentry->d_inode;
+ struct proc_inode *ei;
+ struct mnt_namespace *mnt_ns;
+
+ if (!proc_ns_inode(inode))
+ return false;
+
+ ei = PROC_I(inode);
+ if (ei->ns_ops != &mntns_operations)
+ return false;
+
+ mnt_ns = ei->ns;
+ return current->nsproxy->mnt_ns->seq >= mnt_ns->seq;
+}
+
struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
int flag)
{
int type;
int err = 0;
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(mnt->mnt_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
if (path->dentry != path->mnt->mnt_root)
if (err)
return err;
+ err = -EINVAL;
+ if (mnt_ns_loop(&old_path))
+ goto out;
+
err = lock_mount(path);
if (err)
goto out;
struct mount *p;
struct mount *old;
int err = 0;
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(real_mount(path->mnt)->mnt_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
if (!old_name || !*old_name)
return -EINVAL;
return ERR_PTR(err);
}
-static struct vfsmount *
-do_kern_mount(const char *fstype, int flags, const char *name, void *data)
-{
- struct file_system_type *type = get_fs_type(fstype);
- struct vfsmount *mnt;
- if (!type)
- return ERR_PTR(-ENODEV);
- mnt = vfs_kern_mount(type, flags, name, data);
- if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
- !mnt->mnt_sb->s_subtype)
- mnt = fs_set_subtype(mnt, fstype);
- put_filesystem(type);
- return mnt;
-}
-
/*
* add a mount into a namespace's mount tree
*/
* create a new mount for userspace and request it to be added into the
* namespace's tree
*/
-static int do_new_mount(struct path *path, const char *type, int flags,
+static int do_new_mount(struct path *path, const char *fstype, int flags,
int mnt_flags, const char *name, void *data)
{
+ struct file_system_type *type;
+ struct user_namespace *user_ns;
struct vfsmount *mnt;
int err;
- if (!type)
+ if (!fstype)
return -EINVAL;
/* we need capabilities... */
- if (!capable(CAP_SYS_ADMIN))
+ user_ns = real_mount(path->mnt)->mnt_ns->user_ns;
+ if (!ns_capable(user_ns, CAP_SYS_ADMIN))
return -EPERM;
- mnt = do_kern_mount(type, flags, name, data);
+ type = get_fs_type(fstype);
+ if (!type)
+ return -ENODEV;
+
+ if (user_ns != &init_user_ns) {
+ if (!(type->fs_flags & FS_USERNS_MOUNT)) {
+ put_filesystem(type);
+ return -EPERM;
+ }
+ /* Only in special cases allow devices from mounts
+ * created outside the initial user namespace.
+ */
+ if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) {
+ flags |= MS_NODEV;
+ mnt_flags |= MNT_NODEV;
+ }
+ }
+
+ mnt = vfs_kern_mount(type, flags, name, data);
+ if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
+ !mnt->mnt_sb->s_subtype)
+ mnt = fs_set_subtype(mnt, fstype);
+
+ put_filesystem(type);
if (IS_ERR(mnt))
return PTR_ERR(mnt);
return retval;
}
-static struct mnt_namespace *alloc_mnt_ns(void)
+static void free_mnt_ns(struct mnt_namespace *ns)
+{
+ proc_free_inum(ns->proc_inum);
+ 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
+ * mount namespace, preventing reference counting loops. A 64bit
+ * number incrementing at 10Ghz will take 12,427 years to wrap which
+ * is effectively never, so we can ignore the possibility.
+ */
+static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);
+
+static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
{
struct mnt_namespace *new_ns;
+ int ret;
new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
if (!new_ns)
return ERR_PTR(-ENOMEM);
+ ret = proc_alloc_inum(&new_ns->proc_inum);
+ if (ret) {
+ kfree(new_ns);
+ return ERR_PTR(ret);
+ }
+ new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
atomic_set(&new_ns->count, 1);
new_ns->root = NULL;
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;
}
* 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;
struct mount *p, *q;
struct mount *old = mnt_ns->root;
struct mount *new;
+ int copy_flags;
- new_ns = alloc_mnt_ns();
+ new_ns = alloc_mnt_ns(user_ns);
if (IS_ERR(new_ns))
return new_ns;
down_write(&namespace_sem);
/* First pass: copy the tree topology */
- new = copy_tree(old, old->mnt.mnt_root, CL_COPY_ALL | CL_EXPIRE);
+ copy_flags = CL_COPY_ALL | CL_EXPIRE;
+ if (user_ns != mnt_ns->user_ns)
+ copy_flags |= CL_SHARED_TO_SLAVE;
+ new = copy_tree(old, old->mnt.mnt_root, copy_flags);
if (IS_ERR(new)) {
up_write(&namespace_sem);
- kfree(new_ns);
+ free_mnt_ns(new_ns);
return ERR_CAST(new);
}
new_ns->root = new;
}
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;
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;
*/
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;
struct mount *new_mnt, *root_mnt;
int error;
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
error = user_path_dir(new_root, &new);
struct vfsmount *mnt;
struct mnt_namespace *ns;
struct path root;
+ struct file_system_type *type;
- mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
+ type = get_fs_type("rootfs");
+ if (!type)
+ panic("Can't find rootfs type");
+ mnt = vfs_kern_mount(type, 0, "rootfs", NULL);
+ put_filesystem(type);
if (IS_ERR(mnt))
panic("Can't create rootfs");
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)
{
return check_mnt(real_mount(mnt));
}
+
+static void *mntns_get(struct task_struct *task)
+{
+ struct mnt_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ rcu_read_lock();
+ nsproxy = task_nsproxy(task);
+ if (nsproxy) {
+ ns = nsproxy->mnt_ns;
+ get_mnt_ns(ns);
+ }
+ rcu_read_unlock();
+
+ return ns;
+}
+
+static void mntns_put(void *ns)
+{
+ put_mnt_ns(ns);
+}
+
+static int mntns_install(struct nsproxy *nsproxy, void *ns)
+{
+ struct fs_struct *fs = current->fs;
+ struct mnt_namespace *mnt_ns = ns;
+ struct path root;
+
+ if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
+ !nsown_capable(CAP_SYS_CHROOT) ||
+ !nsown_capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (fs->users != 1)
+ return -EINVAL;
+
+ get_mnt_ns(mnt_ns);
+ put_mnt_ns(nsproxy->mnt_ns);
+ nsproxy->mnt_ns = mnt_ns;
+
+ /* Find the root */
+ root.mnt = &mnt_ns->root->mnt;
+ root.dentry = mnt_ns->root->mnt.mnt_root;
+ path_get(&root);
+ while(d_mountpoint(root.dentry) && follow_down_one(&root))
+ ;
+
+ /* Update the pwd and root */
+ set_fs_pwd(fs, &root);
+ set_fs_root(fs, &root);
+
+ path_put(&root);
+ return 0;
+}
+
+static unsigned int mntns_inum(void *ns)
+{
+ struct mnt_namespace *mnt_ns = ns;
+ return mnt_ns->proc_inum;
+}
+
+const struct proc_ns_operations mntns_operations = {
+ .name = "mnt",
+ .type = CLONE_NEWNS,
+ .get = mntns_get,
+ .put = mntns_put,
+ .install = mntns_install,
+ .inum = mntns_inum,
+};
projects / karo-tx-linux.git / blobdiff