Merge tag 'pull-18-rc1-work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull mount handling updates from Al Viro:
 "Cleanups (and one fix) around struct mount handling.

  The fix is usermode_driver.c one - once you've done kern_mount(), you
  must kern_unmount(); simple mntput() will end up with a leak. Several
  failure exits in there messed up that way... In practice you won't hit
  those particular failure exits without fault injection, though"

* tag 'pull-18-rc1-work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  move mount-related externs from fs.h to mount.h
  blob_to_mnt(): kern_unmount() is needed to undo kern_mount()
  m->mnt_root->d_inode->i_sb is a weird way to spell m->mnt_sb...
  linux/mount.h: trim includes
  uninline may_mount() and don't opencode it in fspick(2)/fsopen(2)

Author: torvalds

arch/alpha/kernel/osf_sys.c

@@ -36,6 +36,7 @@
 #include <linux/types.h>
 #include <linux/ipc.h>
 #include <linux/namei.h>
+#include <linux/mount.h>
 #include <linux/uio.h>
 #include <linux/vfs.h>
 #include <linux/rcupdate.h>

fs/fsopen.c

@@ -119,7 +119,7 @@ SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags)
 	const char *fs_name;
 	int ret;
 
-	if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN))
+	if (!may_mount())
 		return -EPERM;
 
 	if (flags & ~FSOPEN_CLOEXEC)
@@ -162,7 +162,7 @@ SYSCALL_DEFINE3(fspick, int, dfd, const char __user *, path, unsigned int, flags
 	unsigned int lookup_flags;
 	int ret;
 
-	if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN))
+	if (!may_mount())
 		return -EPERM;
 
 	if ((flags & ~(FSPICK_CLOEXEC |

fs/internal.h

@@ -84,6 +84,7 @@ extern int __mnt_want_write_file(struct file *);
 extern void __mnt_drop_write_file(struct file *);
 
 extern void dissolve_on_fput(struct vfsmount *);
+extern bool may_mount(void);
 
 int path_mount(const char *dev_name, struct path *path,
 		const char *type_page, unsigned long flags, void *data_page);

fs/namespace.c

@@ -1760,7 +1760,7 @@ void __detach_mounts(struct dentry *dentry)
 /*
  * Is the caller allowed to modify his namespace?
  */
-static inline bool may_mount(void)
+bool may_mount(void)
 {
 	return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN);
 }

fs/nfs/nfs4file.c

@@ -328,7 +328,7 @@ static struct file *__nfs42_ssc_open(struct vfsmount *ss_mnt,
 	char *read_name = NULL;
 	int len, status = 0;
 
-	server = NFS_SERVER(ss_mnt->mnt_root->d_inode);
+	server = NFS_SB(ss_mnt->mnt_sb);
 
 	if (!fattr)
 		return ERR_PTR(-ENOMEM);
@@ -346,7 +346,7 @@ static struct file *__nfs42_ssc_open(struct vfsmount *ss_mnt,
 		goto out;
 	snprintf(read_name, len, SSC_READ_NAME_BODY, read_name_gen++);
 
-	r_ino = nfs_fhget(ss_mnt->mnt_root->d_inode->i_sb, src_fh, fattr);
+	r_ino = nfs_fhget(ss_mnt->mnt_sb, src_fh, fattr);
 	if (IS_ERR(r_ino)) {
 		res = ERR_CAST(r_ino);
 		goto out_free_name;

include/linux/fs.h

@@ -2469,22 +2469,11 @@ struct super_block *sget(struct file_system_type *type,
 
 extern int register_filesystem(struct file_system_type *);
 extern int unregister_filesystem(struct file_system_type *);
-extern struct vfsmount *kern_mount(struct file_system_type *);
-extern void kern_unmount(struct vfsmount *mnt);
-extern int may_umount_tree(struct vfsmount *);
-extern int may_umount(struct vfsmount *);
-extern long do_mount(const char *, const char __user *,
-		     const char *, unsigned long, void *);
-extern struct vfsmount *collect_mounts(const struct path *);
-extern void drop_collected_mounts(struct vfsmount *);
-extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
-			  struct vfsmount *);
 extern int vfs_statfs(const struct path *, struct kstatfs *);
 extern int user_statfs(const char __user *, struct kstatfs *);
 extern int fd_statfs(int, struct kstatfs *);
 extern int freeze_super(struct super_block *super);
 extern int thaw_super(struct super_block *super);
-extern bool our_mnt(struct vfsmount *mnt);
 extern __printf(2, 3)
 int super_setup_bdi_name(struct super_block *sb, char *fmt, ...);
 extern int super_setup_bdi(struct super_block *sb);

include/linux/mount.h

@@ -11,17 +11,15 @@
 #define _LINUX_MOUNT_H
 
 #include <linux/types.h>
-#include <linux/list.h>
-#include <linux/nodemask.h>
-#include <linux/spinlock.h>
-#include <linux/seqlock.h>
-#include <linux/atomic.h>
+#include <asm/barrier.h>
 
 struct super_block;
-struct vfsmount;
 struct dentry;
-struct mnt_namespace;
+struct user_namespace;
+struct file_system_type;
 struct fs_context;
+struct file;
+struct path;
 
 #define MNT_NOSUID	0x01
 #define MNT_NODEV	0x02
@@ -81,9 +79,6 @@ static inline struct user_namespace *mnt_user_ns(const struct vfsmount *mnt)
 	return smp_load_acquire(&mnt->mnt_userns);
 }
 
-struct file; /* forward dec */
-struct path;
-
 extern int mnt_want_write(struct vfsmount *mnt);
 extern int mnt_want_write_file(struct file *file);
 extern void mnt_drop_write(struct vfsmount *mnt);
@@ -94,12 +89,10 @@ extern struct vfsmount *mnt_clone_internal(const struct path *path);
 extern bool __mnt_is_readonly(struct vfsmount *mnt);
 extern bool mnt_may_suid(struct vfsmount *mnt);
 
-struct path;
 extern struct vfsmount *clone_private_mount(const struct path *path);
 extern int __mnt_want_write(struct vfsmount *);
 extern void __mnt_drop_write(struct vfsmount *);
 
-struct file_system_type;
 extern struct vfsmount *fc_mount(struct fs_context *fc);
 extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
 extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
@@ -115,6 +108,18 @@ extern void mark_mounts_for_expiry(struct list_head *mounts);
 extern dev_t name_to_dev_t(const char *name);
 extern bool path_is_mountpoint(const struct path *path);
 
+extern bool our_mnt(struct vfsmount *mnt);
+
+extern struct vfsmount *kern_mount(struct file_system_type *);
+extern void kern_unmount(struct vfsmount *mnt);
+extern int may_umount_tree(struct vfsmount *);
+extern int may_umount(struct vfsmount *);
+extern long do_mount(const char *, const char __user *,
+		     const char *, unsigned long, void *);
+extern struct vfsmount *collect_mounts(const struct path *);
+extern void drop_collected_mounts(struct vfsmount *);
+extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
+			  struct vfsmount *);
 extern void kern_unmount_array(struct vfsmount *mnt[], unsigned int num);
 
 #endif /* _LINUX_MOUNT_H */

kernel/usermode_driver.c

@@ -28,7 +28,7 @@ static struct vfsmount *blob_to_mnt(const void *data, size_t len, const char *na
 
 	file = file_open_root_mnt(mnt, name, O_CREAT | O_WRONLY, 0700);
 	if (IS_ERR(file)) {
-		mntput(mnt);
+		kern_unmount(mnt);
 		return ERR_CAST(file);
 	}
 
@@ -38,7 +38,7 @@ static struct vfsmount *blob_to_mnt(const void *data, size_t len, const char *na
 		if (err >= 0)
 			err = -ENOMEM;
 		filp_close(file, NULL);
-		mntput(mnt);
+		kern_unmount(mnt);
 		return ERR_PTR(err);
 	}
 

security/smack/smackfs.c

@@ -23,6 +23,7 @@
 #include <linux/ctype.h>
 #include <linux/audit.h>
 #include <linux/magic.h>
+#include <linux/mount.h>
 #include <linux/fs_context.h>
 #include "smack.h"