fs: port xattr to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Christian Brauner (Microsoft) <[e-mail]>

Documentation/filesystems/locking.rst

···
 		   struct inode *inode, const char *name, void *buffer,
 		   size_t size);
 	int (*set)(const struct xattr_handler *handler,
-                   struct user_namespace *mnt_userns,
+                   struct mnt_idmap *idmap,
                    struct dentry *dentry, struct inode *inode, const char *name,
                    const void *buffer, size_t size, int flags);
 

fs/9p/xattr.c

···
 }
 
 static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
-				  struct user_namespace *mnt_userns,
+				  struct mnt_idmap *idmap,
 				  struct dentry *dentry, struct inode *inode,
 				  const char *name, const void *value,
 				  size_t size, int flags)

fs/afs/xattr.c

···
  * Set a file's AFS3 ACL.
  */
 static int afs_xattr_set_acl(const struct xattr_handler *handler,
-			     struct user_namespace *mnt_userns,
+			     struct mnt_idmap *idmap,
                              struct dentry *dentry,
                              struct inode *inode, const char *name,
                              const void *buffer, size_t size, int flags)
···
  * Set a file's YFS ACL.
  */
 static int afs_xattr_set_yfs(const struct xattr_handler *handler,
-			     struct user_namespace *mnt_userns,
+			     struct mnt_idmap *idmap,
                              struct dentry *dentry,
                              struct inode *inode, const char *name,
                              const void *buffer, size_t size, int flags)

fs/attr.c

···
 	if (ia_valid & ATTR_KILL_PRIV) {
 		int error;
 
-		error = security_inode_killpriv(mnt_userns, dentry);
+		error = security_inode_killpriv(idmap, dentry);
 		if (error)
 			return error;
 	}
···
 
 	if (!error) {
 		fsnotify_change(dentry, ia_valid);
-		ima_inode_post_setattr(mnt_userns, dentry);
+		ima_inode_post_setattr(idmap, dentry);
 		evm_inode_post_setattr(dentry, ia_valid);
 	}
 

fs/btrfs/xattr.c

···
 }
 
 static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   struct dentry *unused, struct inode *inode,
 				   const char *name, const void *buffer,
 				   size_t size, int flags)
···
 }
 
 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
-					struct user_namespace *mnt_userns,
+					struct mnt_idmap *idmap,
 					struct dentry *unused, struct inode *inode,
 					const char *name, const void *value,
 					size_t size, int flags)

fs/ceph/xattr.c

···
 }
 
 static int ceph_set_xattr_handler(const struct xattr_handler *handler,
-				  struct user_namespace *mnt_userns,
+				  struct mnt_idmap *idmap,
 				  struct dentry *unused, struct inode *inode,
 				  const char *name, const void *value,
 				  size_t size, int flags)

fs/cifs/xattr.c

···
 }
 
 static int cifs_xattr_set(const struct xattr_handler *handler,
-			  struct user_namespace *mnt_userns,
+			  struct mnt_idmap *idmap,
 			  struct dentry *dentry, struct inode *inode,
 			  const char *name, const void *value,
 			  size_t size, int flags)

fs/ecryptfs/crypto.c

···
 	}
 
 	inode_lock(lower_inode);
-	rc = __vfs_setxattr(&init_user_ns, lower_dentry, lower_inode,
+	rc = __vfs_setxattr(&nop_mnt_idmap, lower_dentry, lower_inode,
 			    ECRYPTFS_XATTR_NAME, page_virt, size, 0);
 	if (!rc && ecryptfs_inode)
 		fsstack_copy_attr_all(ecryptfs_inode, lower_inode);

fs/ecryptfs/inode.c

···
 		goto out;
 	}
 	inode_lock(lower_inode);
-	rc = __vfs_removexattr(&init_user_ns, lower_dentry, name);
+	rc = __vfs_removexattr(&nop_mnt_idmap, lower_dentry, name);
 	inode_unlock(lower_inode);
 out:
 	return rc;
···
 }
 
 static int ecryptfs_xattr_set(const struct xattr_handler *handler,
-			      struct user_namespace *mnt_userns,
+			      struct mnt_idmap *idmap,
 			      struct dentry *dentry, struct inode *inode,
 			      const char *name, const void *value, size_t size,
 			      int flags)

fs/ecryptfs/mmap.c

···
 	if (size < 0)
 		size = 8;
 	put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
-	rc = __vfs_setxattr(&init_user_ns, lower_dentry, lower_inode,
+	rc = __vfs_setxattr(&nop_mnt_idmap, lower_dentry, lower_inode,
 			    ECRYPTFS_XATTR_NAME, xattr_virt, size, 0);
 	inode_unlock(lower_inode);
 	if (rc)

fs/ext2/xattr_security.c

···
 
 static int
 ext2_xattr_security_set(const struct xattr_handler *handler,
-			struct user_namespace *mnt_userns,
+			struct mnt_idmap *idmap,
 			struct dentry *unused, struct inode *inode,
 			const char *name, const void *value,
 			size_t size, int flags)

fs/ext2/xattr_trusted.c

···
 
 static int
 ext2_xattr_trusted_set(const struct xattr_handler *handler,
-		       struct user_namespace *mnt_userns,
+		       struct mnt_idmap *idmap,
 		       struct dentry *unused, struct inode *inode,
 		       const char *name, const void *value,
 		       size_t size, int flags)

fs/ext2/xattr_user.c

···
 
 static int
 ext2_xattr_user_set(const struct xattr_handler *handler,
-		    struct user_namespace *mnt_userns,
+		    struct mnt_idmap *idmap,
 		    struct dentry *unused, struct inode *inode,
 		    const char *name, const void *value,
 		    size_t size, int flags)

fs/ext4/xattr_hurd.c

···
 
 static int
 ext4_xattr_hurd_set(const struct xattr_handler *handler,
-		    struct user_namespace *mnt_userns,
+		    struct mnt_idmap *idmap,
 		    struct dentry *unused, struct inode *inode,
 		    const char *name, const void *value,
 		    size_t size, int flags)

fs/ext4/xattr_security.c

···
 
 static int
 ext4_xattr_security_set(const struct xattr_handler *handler,
-			struct user_namespace *mnt_userns,
+			struct mnt_idmap *idmap,
 			struct dentry *unused, struct inode *inode,
 			const char *name, const void *value,
 			size_t size, int flags)

fs/ext4/xattr_trusted.c

···
 
 static int
 ext4_xattr_trusted_set(const struct xattr_handler *handler,
-		       struct user_namespace *mnt_userns,
+		       struct mnt_idmap *idmap,
 		       struct dentry *unused, struct inode *inode,
 		       const char *name, const void *value,
 		       size_t size, int flags)

fs/ext4/xattr_user.c

···
 
 static int
 ext4_xattr_user_set(const struct xattr_handler *handler,
-		    struct user_namespace *mnt_userns,
+		    struct mnt_idmap *idmap,
 		    struct dentry *unused, struct inode *inode,
 		    const char *name, const void *value,
 		    size_t size, int flags)

fs/f2fs/xattr.c

···
 }
 
 static int f2fs_xattr_generic_set(const struct xattr_handler *handler,
-		struct user_namespace *mnt_userns,
+		struct mnt_idmap *idmap,
 		struct dentry *unused, struct inode *inode,
 		const char *name, const void *value,
 		size_t size, int flags)
···
 }
 
 static int f2fs_xattr_advise_set(const struct xattr_handler *handler,
-		struct user_namespace *mnt_userns,
+		struct mnt_idmap *idmap,
 		struct dentry *unused, struct inode *inode,
 		const char *name, const void *value,
 		size_t size, int flags)

fs/fuse/xattr.c

···
 }
 
 static int fuse_xattr_set(const struct xattr_handler *handler,
-			  struct user_namespace *mnt_userns,
+			  struct mnt_idmap *idmap,
 			  struct dentry *dentry, struct inode *inode,
 			  const char *name, const void *value, size_t size,
 			  int flags)
···
 }
 
 static int no_xattr_set(const struct xattr_handler *handler,
-			struct user_namespace *mnt_userns,
+			struct mnt_idmap *idmap,
 			struct dentry *dentry, struct inode *nodee,
 			const char *name, const void *value,
 			size_t size, int flags)

fs/gfs2/xattr.c

···
 }
 
 static int gfs2_xattr_set(const struct xattr_handler *handler,
-			  struct user_namespace *mnt_userns,
+			  struct mnt_idmap *idmap,
 			  struct dentry *unused, struct inode *inode,
 			  const char *name, const void *value,
 			  size_t size, int flags)

fs/hfs/attr.c

···
 }
 
 static int hfs_xattr_set(const struct xattr_handler *handler,
-			 struct user_namespace *mnt_userns,
+			 struct mnt_idmap *idmap,
 			 struct dentry *unused, struct inode *inode,
 			 const char *name, const void *value, size_t size,
 			 int flags)

fs/hfsplus/xattr.c

···
 }
 
 static int hfsplus_osx_setxattr(const struct xattr_handler *handler,
-				struct user_namespace *mnt_userns,
+				struct mnt_idmap *idmap,
 				struct dentry *unused, struct inode *inode,
 				const char *name, const void *buffer,
 				size_t size, int flags)

fs/hfsplus/xattr_security.c

···
 }
 
 static int hfsplus_security_setxattr(const struct xattr_handler *handler,
-				     struct user_namespace *mnt_userns,
+				     struct mnt_idmap *idmap,
 				     struct dentry *unused, struct inode *inode,
 				     const char *name, const void *buffer,
 				     size_t size, int flags)

fs/hfsplus/xattr_trusted.c

···
 }
 
 static int hfsplus_trusted_setxattr(const struct xattr_handler *handler,
-				    struct user_namespace *mnt_userns,
+				    struct mnt_idmap *idmap,
 				    struct dentry *unused, struct inode *inode,
 				    const char *name, const void *buffer,
 				    size_t size, int flags)

fs/hfsplus/xattr_user.c

···
 }
 
 static int hfsplus_user_setxattr(const struct xattr_handler *handler,
-				 struct user_namespace *mnt_userns,
+				 struct mnt_idmap *idmap,
 				 struct dentry *unused, struct inode *inode,
 				 const char *name, const void *buffer,
 				 size_t size, int flags)

fs/jffs2/security.c

···
 }
 
 static int jffs2_security_setxattr(const struct xattr_handler *handler,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   struct dentry *unused, struct inode *inode,
 				   const char *name, const void *buffer,
 				   size_t size, int flags)

fs/jffs2/xattr_trusted.c

···
 }
 
 static int jffs2_trusted_setxattr(const struct xattr_handler *handler,
-				  struct user_namespace *mnt_userns,
+				  struct mnt_idmap *idmap,
 				  struct dentry *unused, struct inode *inode,
 				  const char *name, const void *buffer,
 				  size_t size, int flags)

fs/jffs2/xattr_user.c

···
 }
 
 static int jffs2_user_setxattr(const struct xattr_handler *handler,
-			       struct user_namespace *mnt_userns,
+			       struct mnt_idmap *idmap,
 			       struct dentry *unused, struct inode *inode,
 			       const char *name, const void *buffer,
 			       size_t size, int flags)

fs/jfs/xattr.c

···
 }
 
 static int jfs_xattr_set(const struct xattr_handler *handler,
-			 struct user_namespace *mnt_userns,
+			 struct mnt_idmap *idmap,
 			 struct dentry *unused, struct inode *inode,
 			 const char *name, const void *value,
 			 size_t size, int flags)
···
 }
 
 static int jfs_xattr_set_os2(const struct xattr_handler *handler,
-			     struct user_namespace *mnt_userns,
+			     struct mnt_idmap *idmap,
 			     struct dentry *unused, struct inode *inode,
 			     const char *name, const void *value,
 			     size_t size, int flags)

fs/kernfs/inode.c

···
 }
 
 static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
-				struct user_namespace *mnt_userns,
+				struct mnt_idmap *idmap,
 				struct dentry *unused, struct inode *inode,
 				const char *suffix, const void *value,
 				size_t size, int flags)
···
 }
 
 static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
-				     struct user_namespace *mnt_userns,
+				     struct mnt_idmap *idmap,
 				     struct dentry *unused, struct inode *inode,
 				     const char *suffix, const void *value,
 				     size_t size, int flags)

fs/namei.c

···
 		inode->i_state |= I_LINKABLE;
 		spin_unlock(&inode->i_lock);
 	}
-	ima_post_create_tmpfile(mnt_userns, inode);
+	ima_post_create_tmpfile(idmap, inode);
 	return 0;
 }
 
···
 		unsigned int dev)
 {
 	struct mnt_idmap *idmap;
-	struct user_namespace *mnt_userns;
 	struct dentry *dentry;
 	struct path path;
 	int error;
···
 		goto out2;
 
 	idmap = mnt_idmap(path.mnt);
-	mnt_userns = mnt_idmap_owner(idmap);
 	switch (mode & S_IFMT) {
 		case 0: case S_IFREG:
 			error = vfs_create(idmap, path.dentry->d_inode,
 					   dentry, mode, true);
 			if (!error)
-				ima_post_path_mknod(mnt_userns, dentry);
+				ima_post_path_mknod(idmap, dentry);
 			break;
 		case S_IFCHR: case S_IFBLK:
 			error = vfs_mknod(idmap, path.dentry->d_inode,

fs/nfs/nfs4proc.c

···
 #define XATTR_NAME_NFSV4_ACL "system.nfs4_acl"
 
 static int nfs4_xattr_set_nfs4_acl(const struct xattr_handler *handler,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   struct dentry *unused, struct inode *inode,
 				   const char *key, const void *buf,
 				   size_t buflen, int flags)
···
 #define XATTR_NAME_NFSV4_DACL "system.nfs4_dacl"
 
 static int nfs4_xattr_set_nfs4_dacl(const struct xattr_handler *handler,
-				    struct user_namespace *mnt_userns,
+				    struct mnt_idmap *idmap,
 				    struct dentry *unused, struct inode *inode,
 				    const char *key, const void *buf,
 				    size_t buflen, int flags)
···
 #define XATTR_NAME_NFSV4_SACL "system.nfs4_sacl"
 
 static int nfs4_xattr_set_nfs4_sacl(const struct xattr_handler *handler,
-				    struct user_namespace *mnt_userns,
+				    struct mnt_idmap *idmap,
 				    struct dentry *unused, struct inode *inode,
 				    const char *key, const void *buf,
 				    size_t buflen, int flags)
···
 #ifdef CONFIG_NFS_V4_SECURITY_LABEL
 
 static int nfs4_xattr_set_nfs4_label(const struct xattr_handler *handler,
-				     struct user_namespace *mnt_userns,
+				     struct mnt_idmap *idmap,
 				     struct dentry *unused, struct inode *inode,
 				     const char *key, const void *buf,
 				     size_t buflen, int flags)
···
 
 #ifdef CONFIG_NFS_V4_2
 static int nfs4_xattr_set_nfs4_user(const struct xattr_handler *handler,
-				    struct user_namespace *mnt_userns,
+				    struct mnt_idmap *idmap,
 				    struct dentry *unused, struct inode *inode,
 				    const char *key, const void *buf,
 				    size_t buflen, int flags)

fs/ntfs3/xattr.c

···
  * ntfs_setxattr - inode_operations::setxattr
  */
 static noinline int ntfs_setxattr(const struct xattr_handler *handler,
-				  struct user_namespace *mnt_userns,
+				  struct mnt_idmap *idmap,
 				  struct dentry *de, struct inode *inode,
 				  const char *name, const void *value,
 				  size_t size, int flags)

fs/ocfs2/xattr.c

···
 }
 
 static int ocfs2_xattr_security_set(const struct xattr_handler *handler,
-				    struct user_namespace *mnt_userns,
+				    struct mnt_idmap *idmap,
 				    struct dentry *unused, struct inode *inode,
 				    const char *name, const void *value,
 				    size_t size, int flags)
···
 }
 
 static int ocfs2_xattr_trusted_set(const struct xattr_handler *handler,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   struct dentry *unused, struct inode *inode,
 				   const char *name, const void *value,
 				   size_t size, int flags)
···
 }
 
 static int ocfs2_xattr_user_set(const struct xattr_handler *handler,
-				struct user_namespace *mnt_userns,
+				struct mnt_idmap *idmap,
 				struct dentry *unused, struct inode *inode,
 				const char *name, const void *value,
 				size_t size, int flags)

fs/orangefs/xattr.c

···
 }
 
 static int orangefs_xattr_set_default(const struct xattr_handler *handler,
-				      struct user_namespace *mnt_userns,
+				      struct mnt_idmap *idmap,
 				      struct dentry *unused,
 				      struct inode *inode,
 				      const char *name,

fs/overlayfs/super.c

···
 }
 
 static int ovl_own_xattr_set(const struct xattr_handler *handler,
-			     struct user_namespace *mnt_userns,
+			     struct mnt_idmap *idmap,
 			     struct dentry *dentry, struct inode *inode,
 			     const char *name, const void *value,
 			     size_t size, int flags)
···
 }
 
 static int ovl_other_xattr_set(const struct xattr_handler *handler,
-			       struct user_namespace *mnt_userns,
+			       struct mnt_idmap *idmap,
 			       struct dentry *dentry, struct inode *inode,
 			       const char *name, const void *value,
 			       size_t size, int flags)

fs/reiserfs/xattr_security.c

···
 
 static int
 security_set(const struct xattr_handler *handler,
-	     struct user_namespace *mnt_userns, struct dentry *unused,
+	     struct mnt_idmap *idmap, struct dentry *unused,
 	     struct inode *inode, const char *name, const void *buffer,
 	     size_t size, int flags)
 {

fs/reiserfs/xattr_trusted.c

···
 
 static int
 trusted_set(const struct xattr_handler *handler,
-	    struct user_namespace *mnt_userns, struct dentry *unused,
+	    struct mnt_idmap *idmap, struct dentry *unused,
 	    struct inode *inode, const char *name, const void *buffer,
 	    size_t size, int flags)
 {

fs/reiserfs/xattr_user.c

···
 }
 
 static int
-user_set(const struct xattr_handler *handler, struct user_namespace *mnt_userns,
+user_set(const struct xattr_handler *handler, struct mnt_idmap *idmap,
 	 struct dentry *unused,
 	 struct inode *inode, const char *name, const void *buffer,
 	 size_t size, int flags)

fs/ubifs/xattr.c

···
 }
 
 static int xattr_set(const struct xattr_handler *handler,
-			   struct user_namespace *mnt_userns,
+			   struct mnt_idmap *idmap,
 			   struct dentry *dentry, struct inode *inode,
 			   const char *name, const void *value,
 			   size_t size, int flags)

fs/xattr.c

···
 EXPORT_SYMBOL(xattr_supported_namespace);
 
 int
-__vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+__vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	       struct inode *inode, const char *name, const void *value,
 	       size_t size, int flags)
 {
···
 		return -EOPNOTSUPP;
 	if (size == 0)
 		value = "";  /* empty EA, do not remove */
-	return handler->set(handler, mnt_userns, dentry, inode, name, value,
+	return handler->set(handler, idmap, dentry, inode, name, value,
 			    size, flags);
 }
 EXPORT_SYMBOL(__vfs_setxattr);
···
  *  __vfs_setxattr_noperm - perform setxattr operation without performing
  *  permission checks.
  *
- *  @mnt_userns: user namespace of the mount the inode was found from
+ *  @idmap: idmap of the mount the inode was found from
  *  @dentry: object to perform setxattr on
  *  @name: xattr name to set
  *  @value: value to set @name to
···
  *  is executed. It also assumes that the caller will make the appropriate
  *  permission checks.
  */
-int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
+int __vfs_setxattr_noperm(struct mnt_idmap *idmap,
 			  struct dentry *dentry, const char *name,
 			  const void *value, size_t size, int flags)
 {
···
 	if (issec)
 		inode->i_flags &= ~S_NOSEC;
 	if (inode->i_opflags & IOP_XATTR) {
-		error = __vfs_setxattr(mnt_userns, dentry, inode, name, value,
+		error = __vfs_setxattr(idmap, dentry, inode, name, value,
 				       size, flags);
 		if (!error) {
 			fsnotify_xattr(dentry);
···
 		      const char *name, const void *value, size_t size,
 		      int flags, struct inode **delegated_inode)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = dentry->d_inode;
 	int error;
 
···
 	if (error)
 		return error;
 
-	error = security_inode_setxattr(mnt_userns, dentry, name, value, size,
+	error = security_inode_setxattr(idmap, dentry, name, value, size,
 					flags);
 	if (error)
 		goto out;
···
 	if (error)
 		goto out;
 
-	error = __vfs_setxattr_noperm(mnt_userns, dentry, name, value,
+	error = __vfs_setxattr_noperm(idmap, dentry, name, value,
 				      size, flags);
 
 out:
···
 vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	     const char *name, const void *value, size_t size, int flags)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = dentry->d_inode;
 	struct inode *delegated_inode = NULL;
 	const void  *orig_value = value;
 	int error;
 
 	if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
-		error = cap_convert_nscap(mnt_userns, dentry, &value, size);
+		error = cap_convert_nscap(idmap, dentry, &value, size);
 		if (error < 0)
 			return error;
 		size = error;
···
 EXPORT_SYMBOL_GPL(vfs_listxattr);
 
 int
-__vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+__vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		  const char *name)
 {
 	struct inode *inode = d_inode(dentry);
···
 		return PTR_ERR(handler);
 	if (!handler->set)
 		return -EOPNOTSUPP;
-	return handler->set(handler, mnt_userns, dentry, inode, name, NULL, 0,
+	return handler->set(handler, idmap, dentry, inode, name, NULL, 0,
 			    XATTR_REPLACE);
 }
 EXPORT_SYMBOL(__vfs_removexattr);
···
 			 struct dentry *dentry, const char *name,
 			 struct inode **delegated_inode)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = dentry->d_inode;
 	int error;
 
···
 	if (error)
 		return error;
 
-	error = security_inode_removexattr(mnt_userns, dentry, name);
+	error = security_inode_removexattr(idmap, dentry, name);
 	if (error)
 		goto out;
 
···
 	if (error)
 		goto out;
 
-	error = __vfs_removexattr(mnt_userns, dentry, name);
+	error = __vfs_removexattr(idmap, dentry, name);
 
 	if (!error) {
 		fsnotify_xattr(dentry);

fs/xfs/xfs_xattr.c

···
 
 static int
 xfs_xattr_set(const struct xattr_handler *handler,
-	      struct user_namespace *mnt_userns, struct dentry *unused,
+	      struct mnt_idmap *idmap, struct dentry *unused,
 	      struct inode *inode, const char *name, const void *value,
 	      size_t size, int flags)
 {

include/linux/capability.h

···
 struct dentry;
 struct task_struct;
 struct user_namespace;
+struct mnt_idmap;
 
 extern const kernel_cap_t __cap_empty_set;
 extern const kernel_cap_t __cap_init_eff_set;
···
 }
 
 /* audit system wants to get cap info from files as well */
-int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
+int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
 			   const struct dentry *dentry,
 			   struct cpu_vfs_cap_data *cpu_caps);
 
-int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
+int cap_convert_nscap(struct mnt_idmap *idmap, struct dentry *dentry,
 		      const void **ivalue, size_t size);
 
 #endif /* !_LINUX_CAPABILITY_H */

include/linux/evm.h

···
 extern int evm_inode_setattr(struct mnt_idmap *idmap,
 			     struct dentry *dentry, struct iattr *attr);
 extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid);
-extern int evm_inode_setxattr(struct user_namespace *mnt_userns,
+extern int evm_inode_setxattr(struct mnt_idmap *idmap,
 			      struct dentry *dentry, const char *name,
 			      const void *value, size_t size);
 extern void evm_inode_post_setxattr(struct dentry *dentry,
 				    const char *xattr_name,
 				    const void *xattr_value,
 				    size_t xattr_value_len);
-extern int evm_inode_removexattr(struct user_namespace *mnt_userns,
+extern int evm_inode_removexattr(struct mnt_idmap *idmap,
 				 struct dentry *dentry, const char *xattr_name);
 extern void evm_inode_post_removexattr(struct dentry *dentry,
 				       const char *xattr_name);
···
 	return;
 }
 
-static inline int evm_inode_setxattr(struct user_namespace *mnt_userns,
+static inline int evm_inode_setxattr(struct mnt_idmap *idmap,
 				     struct dentry *dentry, const char *name,
 				     const void *value, size_t size)
 {
···
 	return;
 }
 
-static inline int evm_inode_removexattr(struct user_namespace *mnt_userns,
+static inline int evm_inode_removexattr(struct mnt_idmap *idmap,
 					struct dentry *dentry,
 					const char *xattr_name)
 {

include/linux/ima.h

···
 extern enum hash_algo ima_get_current_hash_algo(void);
 extern int ima_bprm_check(struct linux_binprm *bprm);
 extern int ima_file_check(struct file *file, int mask);
-extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
+extern void ima_post_create_tmpfile(struct mnt_idmap *idmap,
 				    struct inode *inode);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
···
 			 bool contents);
 extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
 			      enum kernel_read_file_id id);
-extern void ima_post_path_mknod(struct user_namespace *mnt_userns,
+extern void ima_post_path_mknod(struct mnt_idmap *idmap,
 				struct dentry *dentry);
 extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
 extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size);
···
 	return 0;
 }
 
-static inline void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
+static inline void ima_post_create_tmpfile(struct mnt_idmap *idmap,
 					   struct inode *inode)
 {
 }
···
 	return 0;
 }
 
-static inline void ima_post_path_mknod(struct user_namespace *mnt_userns,
+static inline void ima_post_path_mknod(struct mnt_idmap *idmap,
 				       struct dentry *dentry)
 {
 	return;
···
 
 #ifdef CONFIG_IMA_APPRAISE
 extern bool is_ima_appraise_enabled(void);
-extern void ima_inode_post_setattr(struct user_namespace *mnt_userns,
+extern void ima_inode_post_setattr(struct mnt_idmap *idmap,
 				   struct dentry *dentry);
 extern int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
 		       const void *xattr_value, size_t xattr_value_len);
···
 	return 0;
 }
 
-static inline void ima_inode_post_setattr(struct user_namespace *mnt_userns,
+static inline void ima_inode_post_setattr(struct mnt_idmap *idmap,
 					  struct dentry *dentry)
 {
 	return;

include/linux/lsm_hook_defs.h

···
 LSM_HOOK(int, 0, inode_permission, struct inode *inode, int mask)
 LSM_HOOK(int, 0, inode_setattr, struct dentry *dentry, struct iattr *attr)
 LSM_HOOK(int, 0, inode_getattr, const struct path *path)
-LSM_HOOK(int, 0, inode_setxattr, struct user_namespace *mnt_userns,
+LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name, const void *value,
 	 size_t size, int flags)
 LSM_HOOK(void, LSM_RET_VOID, inode_post_setxattr, struct dentry *dentry,
 	 const char *name, const void *value, size_t size, int flags)
 LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
-LSM_HOOK(int, 0, inode_removexattr, struct user_namespace *mnt_userns,
+LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_set_acl, struct user_namespace *mnt_userns,
 	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
···
 LSM_HOOK(int, 0, inode_remove_acl, struct user_namespace *mnt_userns,
 	 struct dentry *dentry, const char *acl_name)
 LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry)
-LSM_HOOK(int, 0, inode_killpriv, struct user_namespace *mnt_userns,
+LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap,
 	 struct dentry *dentry)
 LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap,
 	 struct inode *inode, const char *name, void **buffer, bool alloc)

include/linux/lsm_hooks.h

···
  * @inode_killpriv:
  *	The setuid bit is being removed.  Remove similar security labels.
  *	Called with the dentry->d_inode->i_mutex held.
- *	@mnt_userns: user namespace of the mount.
+ *	@idmap: idmap of the mount.
  *	@dentry is the dentry being changed.
  *	Return 0 on success.  If error is returned, then the operation
  *	causing setuid bit removal is failed.

include/linux/security.h

···
 extern int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file);
 int cap_inode_setxattr(struct dentry *dentry, const char *name,
 		       const void *value, size_t size, int flags);
-int cap_inode_removexattr(struct user_namespace *mnt_userns,
+int cap_inode_removexattr(struct mnt_idmap *idmap,
 			  struct dentry *dentry, const char *name);
 int cap_inode_need_killpriv(struct dentry *dentry);
-int cap_inode_killpriv(struct user_namespace *mnt_userns,
-		       struct dentry *dentry);
+int cap_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
 int cap_inode_getsecurity(struct mnt_idmap *idmap,
 			  struct inode *inode, const char *name, void **buffer,
 			  bool alloc);
···
 int security_inode_setattr(struct mnt_idmap *idmap,
 			   struct dentry *dentry, struct iattr *attr);
 int security_inode_getattr(const struct path *path);
-int security_inode_setxattr(struct user_namespace *mnt_userns,
+int security_inode_setxattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry, const char *name,
 			    const void *value, size_t size, int flags);
 int security_inode_set_acl(struct user_namespace *mnt_userns,
···
 				  const void *value, size_t size, int flags);
 int security_inode_getxattr(struct dentry *dentry, const char *name);
 int security_inode_listxattr(struct dentry *dentry);
-int security_inode_removexattr(struct user_namespace *mnt_userns,
+int security_inode_removexattr(struct mnt_idmap *idmap,
 			       struct dentry *dentry, const char *name);
 int security_inode_need_killpriv(struct dentry *dentry);
-int security_inode_killpriv(struct user_namespace *mnt_userns,
-			    struct dentry *dentry);
+int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
 int security_inode_getsecurity(struct mnt_idmap *idmap,
 			       struct inode *inode, const char *name,
 			       void **buffer, bool alloc);
···
 	return 0;
 }
 
-static inline int security_inode_setxattr(struct user_namespace *mnt_userns,
+static inline int security_inode_setxattr(struct mnt_idmap *idmap,
 		struct dentry *dentry, const char *name, const void *value,
 		size_t size, int flags)
 {
···
 	return 0;
 }
 
-static inline int security_inode_removexattr(struct user_namespace *mnt_userns,
+static inline int security_inode_removexattr(struct mnt_idmap *idmap,
 					     struct dentry *dentry,
 					     const char *name)
 {
-	return cap_inode_removexattr(mnt_userns, dentry, name);
+	return cap_inode_removexattr(idmap, dentry, name);
 }
 
 static inline int security_inode_need_killpriv(struct dentry *dentry)
···
 	return cap_inode_need_killpriv(dentry);
 }
 
-static inline int security_inode_killpriv(struct user_namespace *mnt_userns,
+static inline int security_inode_killpriv(struct mnt_idmap *idmap,
 					  struct dentry *dentry)
 {
-	return cap_inode_killpriv(mnt_userns, dentry);
+	return cap_inode_killpriv(idmap, dentry);
 }
 
 static inline int security_inode_getsecurity(struct mnt_idmap *idmap,

include/linux/xattr.h

···
 		   struct inode *inode, const char *name, void *buffer,
 		   size_t size);
 	int (*set)(const struct xattr_handler *,
-		   struct user_namespace *mnt_userns, struct dentry *dentry,
+		   struct mnt_idmap *idmap, struct dentry *dentry,
 		   struct inode *inode, const char *name, const void *buffer,
 		   size_t size, int flags);
 };
···
 ssize_t vfs_getxattr(struct mnt_idmap *, struct dentry *, const char *,
 		     void *, size_t);
 ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
-int __vfs_setxattr(struct user_namespace *, struct dentry *, struct inode *,
+int __vfs_setxattr(struct mnt_idmap *, struct dentry *, struct inode *,
 		   const char *, const void *, size_t, int);
-int __vfs_setxattr_noperm(struct user_namespace *, struct dentry *,
+int __vfs_setxattr_noperm(struct mnt_idmap *, struct dentry *,
 			  const char *, const void *, size_t, int);
 int __vfs_setxattr_locked(struct mnt_idmap *, struct dentry *,
 			  const char *, const void *, size_t, int,
 			  struct inode **);
 int vfs_setxattr(struct mnt_idmap *, struct dentry *, const char *,
 		 const void *, size_t, int);
-int __vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
+int __vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
 int __vfs_removexattr_locked(struct mnt_idmap *, struct dentry *,
 			     const char *, struct inode **);
 int vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);

kernel/auditsc.c

···
 	if (!dentry)
 		return 0;
 
-	rc = get_vfs_caps_from_disk(&init_user_ns, dentry, &caps);
+	rc = get_vfs_caps_from_disk(&nop_mnt_idmap, dentry, &caps);
 	if (rc)
 		return rc;
 
···
 	ax->d.next = context->aux;
 	context->aux = (void *)ax;
 
-	get_vfs_caps_from_disk(&init_user_ns,
+	get_vfs_caps_from_disk(&nop_mnt_idmap,
 			       bprm->file->f_path.dentry, &vcaps);
 
 	ax->fcap.permitted = vcaps.permitted;

mm/shmem.c

···
 }
 
 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   struct dentry *unused, struct inode *inode,
 				   const char *name, const void *value,
 				   size_t size, int flags)

net/socket.c

···
 };
 
 static int sockfs_security_xattr_set(const struct xattr_handler *handler,
-				     struct user_namespace *mnt_userns,
+				     struct mnt_idmap *idmap,
 				     struct dentry *dentry, struct inode *inode,
 				     const char *suffix, const void *value,
 				     size_t size, int flags)

security/commoncap.c

···
 /**
  * cap_inode_killpriv - Erase the security markings on an inode
  *
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap:	idmap of the mount the inode was found from
  * @dentry:	The inode/dentry to alter
  *
  * Erase the privilege-enhancing security markings on an inode.
  *
- * If the inode has been found through an idmapped mount the user namespace of
- * the vfsmount must be passed through @mnt_userns. This function will then
- * take care to map the inode according to @mnt_userns before checking
+ * If the inode has been found through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then
+ * take care to map the inode according to @idmap before checking
  * permissions. On non-idmapped mounts or if permission checking is to be
- * performed on the raw inode simply passs init_user_ns.
+ * performed on the raw inode simply passs @nop_mnt_idmap.
  *
  * Return: 0 if successful, -ve on error.
  */
-int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry)
+int cap_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry)
 {
 	int error;
 
-	error = __vfs_removexattr(mnt_userns, dentry, XATTR_NAME_CAPS);
+	error = __vfs_removexattr(idmap, dentry, XATTR_NAME_CAPS);
 	if (error == -EOPNOTSUPP)
 		error = 0;
 	return error;
···
 /**
  * cap_convert_nscap - check vfs caps
  *
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap:	idmap of the mount the inode was found from
  * @dentry:	used to retrieve inode to check permissions on
  * @ivalue:	vfs caps value which may be modified by this function
  * @size:	size of @ivalue
···
  * User requested a write of security.capability.  If needed, update the
  * xattr to change from v2 to v3, or to fixup the v3 rootid.
  *
- * If the inode has been found through an idmapped mount the user namespace of
- * the vfsmount must be passed through @mnt_userns. This function will then
- * take care to map the inode according to @mnt_userns before checking
+ * If the inode has been found through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then
+ * take care to map the inode according to @idmap before checking
  * permissions. On non-idmapped mounts or if permission checking is to be
- * performed on the raw inode simply passs init_user_ns.
+ * performed on the raw inode simply passs @nop_mnt_idmap.
  *
  * Return: On success, return the new size; on error, return < 0.
  */
-int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
+int cap_convert_nscap(struct mnt_idmap *idmap, struct dentry *dentry,
 		      const void **ivalue, size_t size)
 {
 	struct vfs_ns_cap_data *nscap;
···
 	struct inode *inode = d_backing_inode(dentry);
 	struct user_namespace *task_ns = current_user_ns(),
 		*fs_ns = inode->i_sb->s_user_ns;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	kuid_t rootid;
 	vfsuid_t vfsrootid;
 	size_t newsize;
···
 		return -EINVAL;
 	if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP))
 		return -EPERM;
-	if (size == XATTR_CAPS_SZ_2 && (mnt_userns == fs_ns))
+	if (size == XATTR_CAPS_SZ_2 && (idmap == &nop_mnt_idmap))
 		if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP))
 			/* user is privileged, just write the v2 */
 			return size;
···
 /**
  * get_vfs_caps_from_disk - retrieve vfs caps from disk
  *
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap:	idmap of the mount the inode was found from
  * @dentry:	dentry from which @inode is retrieved
  * @cpu_caps:	vfs capabilities
  *
  * Extract the on-exec-apply capability sets for an executable file.
  *
- * If the inode has been found through an idmapped mount the user namespace of
- * the vfsmount must be passed through @mnt_userns. This function will then
- * take care to map the inode according to @mnt_userns before checking
+ * If the inode has been found through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then
+ * take care to map the inode according to @idmap before checking
  * permissions. On non-idmapped mounts or if permission checking is to be
- * performed on the raw inode simply passs init_user_ns.
+ * performed on the raw inode simply passs @nop_mnt_idmap.
  */
-int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
+int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
 			   const struct dentry *dentry,
 			   struct cpu_vfs_cap_data *cpu_caps)
 {
···
 	kuid_t rootkuid;
 	vfsuid_t rootvfsuid;
 	struct user_namespace *fs_ns;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 
 	memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
 
···
 	if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns))
 		return 0;
 
-	rc = get_vfs_caps_from_disk(file_mnt_user_ns(file),
+	rc = get_vfs_caps_from_disk(file_mnt_idmap(file),
 				    file->f_path.dentry, &vcaps);
 	if (rc < 0) {
 		if (rc == -EINVAL)
···
 /**
  * cap_inode_removexattr - Determine whether an xattr may be removed
  *
- * @mnt_userns:	User namespace of the mount the inode was found from
+ * @idmap:	idmap of the mount the inode was found from
  * @dentry:	The inode/dentry being altered
  * @name:	The name of the xattr to be changed
  *
  * Determine whether an xattr may be removed from an inode, returning 0 if
  * permission is granted, -ve if denied.
  *
- * If the inode has been found through an idmapped mount the user namespace of
- * the vfsmount must be passed through @mnt_userns. This function will then
- * take care to map the inode according to @mnt_userns before checking
+ * If the inode has been found through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then
+ * take care to map the inode according to @idmap before checking
  * permissions. On non-idmapped mounts or if permission checking is to be
- * performed on the raw inode simply passs init_user_ns.
+ * performed on the raw inode simply pass @nop_mnt_idmap.
  *
  * This is used to make sure security xattrs don't get removed by those who
  * aren't privileged to remove them.
  */
-int cap_inode_removexattr(struct user_namespace *mnt_userns,
+int cap_inode_removexattr(struct mnt_idmap *idmap,
 			  struct dentry *dentry, const char *name)
 {
 	struct user_namespace *user_ns = dentry->d_sb->s_user_ns;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 
 	/* Ignore non-security xattrs */
 	if (strncmp(name, XATTR_SECURITY_PREFIX,

security/integrity/evm/evm_crypto.c

···
 			   xattr_value_len, &data);
 	if (rc == 0) {
 		data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
-		rc = __vfs_setxattr_noperm(&init_user_ns, dentry,
+		rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry,
 					   XATTR_NAME_EVM,
 					   &data.hdr.xattr.data[1],
 					   SHA1_DIGEST_SIZE + 1, 0);
 	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
-		rc = __vfs_removexattr(&init_user_ns, dentry, XATTR_NAME_EVM);
+		rc = __vfs_removexattr(&nop_mnt_idmap, dentry, XATTR_NAME_EVM);
 	}
 	return rc;
 }

security/integrity/evm/evm_main.c

···
 
 /*
  * evm_xattr_change - check if passed xattr value differs from current value
- * @mnt_userns: user namespace of the idmapped mount
+ * @idmap: idmap of the mount
  * @dentry: pointer to the affected dentry
  * @xattr_name: requested xattr
  * @xattr_value: requested xattr value
···
  *
  * Returns 1 if passed xattr value differs from current value, 0 otherwise.
  */
-static int evm_xattr_change(struct user_namespace *mnt_userns,
+static int evm_xattr_change(struct mnt_idmap *idmap,
 			    struct dentry *dentry, const char *xattr_name,
 			    const void *xattr_value, size_t xattr_value_len)
 {
···
  * For posix xattr acls only, permit security.evm, even if it currently
  * doesn't exist, to be updated unless the EVM signature is immutable.
  */
-static int evm_protect_xattr(struct user_namespace *mnt_userns,
+static int evm_protect_xattr(struct mnt_idmap *idmap,
 			     struct dentry *dentry, const char *xattr_name,
 			     const void *xattr_value, size_t xattr_value_len)
 {
···
 		return 0;
 
 	if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
-	    !evm_xattr_change(mnt_userns, dentry, xattr_name, xattr_value,
+	    !evm_xattr_change(idmap, dentry, xattr_name, xattr_value,
 			      xattr_value_len))
 		return 0;
 
···
 
 /**
  * evm_inode_setxattr - protect the EVM extended attribute
- * @mnt_userns: user namespace of the idmapped mount
+ * @idmap: idmap of the mount
  * @dentry: pointer to the affected dentry
  * @xattr_name: pointer to the affected extended attribute name
  * @xattr_value: pointer to the new extended attribute value
···
  * userspace from writing HMAC value.  Writing 'security.evm' requires
  * requires CAP_SYS_ADMIN privileges.
  */
-int evm_inode_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int evm_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		       const char *xattr_name, const void *xattr_value,
 		       size_t xattr_value_len)
 {
···
 		    xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG)
 			return -EPERM;
 	}
-	return evm_protect_xattr(mnt_userns, dentry, xattr_name, xattr_value,
+	return evm_protect_xattr(idmap, dentry, xattr_name, xattr_value,
 				 xattr_value_len);
 }
 
 /**
  * evm_inode_removexattr - protect the EVM extended attribute
- * @mnt_userns: user namespace of the idmapped mount
+ * @idmap: idmap of the mount
  * @dentry: pointer to the affected dentry
  * @xattr_name: pointer to the affected extended attribute name
  *
  * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
  * the current value is valid.
  */
-int evm_inode_removexattr(struct user_namespace *mnt_userns,
+int evm_inode_removexattr(struct mnt_idmap *idmap,
 			  struct dentry *dentry, const char *xattr_name)
 {
 	/* Policy permits modification of the protected xattrs even though
···
 	if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
 		return 0;
 
-	return evm_protect_xattr(mnt_userns, dentry, xattr_name, NULL, 0);
+	return evm_protect_xattr(idmap, dentry, xattr_name, NULL, 0);
 }
 
 #ifdef CONFIG_FS_POSIX_ACL

security/integrity/ima/ima.h

···
 #endif /* CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS */
 
 /* LIM API function definitions */
-int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_get_action(struct mnt_idmap *idmap, struct inode *inode,
 		   const struct cred *cred, u32 secid, int mask,
 		   enum ima_hooks func, int *pcr,
 		   struct ima_template_desc **template_desc,
···
 			   struct evm_ima_xattr_data *xattr_value,
 			   int xattr_len, const struct modsig *modsig, int pcr,
 			   struct ima_template_desc *template_desc);
-int process_buffer_measurement(struct user_namespace *mnt_userns,
+int process_buffer_measurement(struct mnt_idmap *idmap,
 			       struct inode *inode, const void *buf, int size,
 			       const char *eventname, enum ima_hooks func,
 			       int pcr, const char *func_data,
···
 const char *ima_d_path(const struct path *path, char **pathbuf, char *filename);
 
 /* IMA policy related functions */
-int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_match_policy(struct mnt_idmap *idmap, struct inode *inode,
 		     const struct cred *cred, u32 secid, enum ima_hooks func,
 		     int mask, int flags, int *pcr,
 		     struct ima_template_desc **template_desc,
···
 			     struct file *file, const unsigned char *filename,
 			     struct evm_ima_xattr_data *xattr_value,
 			     int xattr_len, const struct modsig *modsig);
-int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_must_appraise(struct mnt_idmap *idmap, struct inode *inode,
 		      int mask, enum ima_hooks func);
 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file);
 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
···
 	return INTEGRITY_UNKNOWN;
 }
 
-static inline int ima_must_appraise(struct user_namespace *mnt_userns,
+static inline int ima_must_appraise(struct mnt_idmap *idmap,
 				    struct inode *inode, int mask,
 				    enum ima_hooks func)
 {

security/integrity/ima/ima_api.c

···
 
 /**
  * ima_get_action - appraise & measure decision based on policy.
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: pointer to the inode associated with the object being validated
  * @cred: pointer to credentials structure to validate
  * @secid: secid of the task being validated
···
  * Returns IMA_MEASURE, IMA_APPRAISE mask.
  *
  */
-int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_get_action(struct mnt_idmap *idmap, struct inode *inode,
 		   const struct cred *cred, u32 secid, int mask,
 		   enum ima_hooks func, int *pcr,
 		   struct ima_template_desc **template_desc,
···
 
 	flags &= ima_policy_flag;
 
-	return ima_match_policy(mnt_userns, inode, cred, secid, func, mask,
+	return ima_match_policy(idmap, inode, cred, secid, func, mask,
 				flags, pcr, template_desc, func_data,
 				allowed_algos);
 }

security/integrity/ima/ima_appraise.c

···
  *
  * Return 1 to appraise or hash
  */
-int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_must_appraise(struct mnt_idmap *idmap, struct inode *inode,
 		      int mask, enum ima_hooks func)
 {
 	u32 secid;
···
 		return 0;
 
 	security_current_getsecid_subj(&secid);
-	return ima_match_policy(mnt_userns, inode, current_cred(), secid,
+	return ima_match_policy(idmap, inode, current_cred(), secid,
 				func, mask, IMA_APPRAISE | IMA_HASH, NULL,
 				NULL, NULL, NULL);
 }
···
 		iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
 		iint->ima_hash->xattr.ng.algo = algo;
 	}
-	rc = __vfs_setxattr_noperm(&init_user_ns, dentry, XATTR_NAME_IMA,
+	rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_IMA,
 				   &iint->ima_hash->xattr.data[offset],
 				   (sizeof(iint->ima_hash->xattr) - offset) +
 				   iint->ima_hash->length, 0);
···
 
 		rc = is_binary_blacklisted(digest, digestsize);
 		if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
-			process_buffer_measurement(&init_user_ns, NULL, digest, digestsize,
+			process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize,
 						   "blacklisted-hash", NONE,
 						   pcr, NULL, false, NULL, 0);
 	}
···
 
 /**
  * ima_inode_post_setattr - reflect file metadata changes
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap:  idmap of the mount the inode was found from
  * @dentry: pointer to the affected dentry
  *
  * Changes to a dentry's metadata might result in needing to appraise.
···
  * This function is called from notify_change(), which expects the caller
  * to lock the inode's i_mutex.
  */
-void ima_inode_post_setattr(struct user_namespace *mnt_userns,
+void ima_inode_post_setattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry)
 {
 	struct inode *inode = d_backing_inode(dentry);
···
 	    || !(inode->i_opflags & IOP_XATTR))
 		return;
 
-	action = ima_must_appraise(mnt_userns, inode, MAY_ACCESS, POST_SETATTR);
+	action = ima_must_appraise(idmap, inode, MAY_ACCESS, POST_SETATTR);
 	iint = integrity_iint_find(inode);
 	if (iint) {
 		set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags);

security/integrity/ima/ima_asymmetric_keys.c

···
 	 * if the IMA policy is configured to measure a key linked
 	 * to the given keyring.
 	 */
-	process_buffer_measurement(&init_user_ns, NULL, payload, payload_len,
+	process_buffer_measurement(&nop_mnt_idmap, NULL, payload, payload_len,
 				   keyring->description, KEY_CHECK, 0,
 				   keyring->description, false, NULL, 0);
 }

security/integrity/ima/ima_main.c

···
 	 * bitmask based on the appraise/audit/measurement policy.
 	 * Included is the appraise submask.
 	 */
-	action = ima_get_action(file_mnt_user_ns(file), inode, cred, secid,
+	action = ima_get_action(file_mnt_idmap(file), inode, cred, secid,
 				mask, func, &pcr, &template_desc, NULL,
 				&allowed_algos);
 	violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
···
 
 	security_current_getsecid_subj(&secid);
 	inode = file_inode(vma->vm_file);
-	action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
+	action = ima_get_action(file_mnt_idmap(vma->vm_file), inode,
 				current_cred(), secid, MAY_EXEC, MMAP_CHECK,
 				&pcr, &template, NULL, NULL);
 
···
 
 /**
  * ima_post_create_tmpfile - mark newly created tmpfile as new
- * @mnt_userns: user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: inode of the newly created tmpfile
  *
  * No measuring, appraising or auditing of newly created tmpfiles is needed.
  * Skip calling process_measurement(), but indicate which newly, created
  * tmpfiles are in policy.
  */
-void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
+void ima_post_create_tmpfile(struct mnt_idmap *idmap,
 			     struct inode *inode)
 {
 	struct integrity_iint_cache *iint;
···
 	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 		return;
 
-	must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS,
+	must_appraise = ima_must_appraise(idmap, inode, MAY_ACCESS,
 					  FILE_CHECK);
 	if (!must_appraise)
 		return;
···
 
 /**
  * ima_post_path_mknod - mark as a new inode
- * @mnt_userns: user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @dentry: newly created dentry
  *
  * Mark files created via the mknodat syscall as new, so that the
  * file data can be written later.
  */
-void ima_post_path_mknod(struct user_namespace *mnt_userns,
+void ima_post_path_mknod(struct mnt_idmap *idmap,
 			 struct dentry *dentry)
 {
 	struct integrity_iint_cache *iint;
···
 	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 		return;
 
-	must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS,
+	must_appraise = ima_must_appraise(idmap, inode, MAY_ACCESS,
 					  FILE_CHECK);
 	if (!must_appraise)
 		return;
···
 
 /**
  * process_buffer_measurement - Measure the buffer or the buffer data hash
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: inode associated with the object being measured (NULL for KEY_CHECK)
  * @buf: pointer to the buffer that needs to be added to the log.
  * @size: size of buffer(in bytes).
···
  * has been written to the passed location but not added to a measurement entry,
  * a negative value otherwise.
  */
-int process_buffer_measurement(struct user_namespace *mnt_userns,
+int process_buffer_measurement(struct mnt_idmap *idmap,
 			       struct inode *inode, const void *buf, int size,
 			       const char *eventname, enum ima_hooks func,
 			       int pcr, const char *func_data,
···
 	 */
 	if (func) {
 		security_current_getsecid_subj(&secid);
-		action = ima_get_action(mnt_userns, inode, current_cred(),
+		action = ima_get_action(idmap, inode, current_cred(),
 					secid, 0, func, &pcr, &template,
 					func_data, NULL);
 		if (!(action & IMA_MEASURE) && !digest)
···
 	if (!f.file)
 		return;
 
-	process_buffer_measurement(file_mnt_user_ns(f.file), file_inode(f.file),
+	process_buffer_measurement(file_mnt_idmap(f.file), file_inode(f.file),
 				   buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0,
 				   NULL, false, NULL, 0);
 	fdput(f);
···
 	if (!event_name || !event_label || !buf || !buf_len)
 		return -ENOPARAM;
 
-	return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
+	return process_buffer_measurement(&nop_mnt_idmap, NULL, buf, buf_len,
 					  event_name, CRITICAL_DATA, 0,
 					  event_label, hash, digest,
 					  digest_len);

security/integrity/ima/ima_policy.c

···
 /**
  * ima_match_rules - determine whether an inode matches the policy rule.
  * @rule: a pointer to a rule
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: a pointer to an inode
  * @cred: a pointer to a credentials structure for user validation
  * @secid: the secid of the task to be validated
···
  * Returns true on rule match, false on failure.
  */
 static bool ima_match_rules(struct ima_rule_entry *rule,
-			    struct user_namespace *mnt_userns,
+			    struct mnt_idmap *idmap,
 			    struct inode *inode, const struct cred *cred,
 			    u32 secid, enum ima_hooks func, int mask,
 			    const char *func_data)
···
 	bool result = false;
 	struct ima_rule_entry *lsm_rule = rule;
 	bool rule_reinitialized = false;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 
 	if ((rule->flags & IMA_FUNC) &&
 	    (rule->func != func && func != POST_SETATTR))
···
 
 /**
  * ima_match_policy - decision based on LSM and other conditions
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: pointer to an inode for which the policy decision is being made
  * @cred: pointer to a credentials structure for which the policy decision is
  *        being made
···
  * list when walking it.  Reads are many orders of magnitude more numerous
  * than writes so ima_match_policy() is classical RCU candidate.
  */
-int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_match_policy(struct mnt_idmap *idmap, struct inode *inode,
 		     const struct cred *cred, u32 secid, enum ima_hooks func,
 		     int mask, int flags, int *pcr,
 		     struct ima_template_desc **template_desc,
···
 		if (!(entry->action & actmask))
 			continue;
 
-		if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
+		if (!ima_match_rules(entry, idmap, inode, cred, secid,
 				     func, mask, func_data))
 			continue;
 

security/integrity/ima/ima_queue_keys.c

···
 
 	list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
 		if (!timer_expired)
-			process_buffer_measurement(&init_user_ns, NULL,
+			process_buffer_measurement(&nop_mnt_idmap, NULL,
 						   entry->payload,
 						   entry->payload_len,
 						   entry->keyring_name,

security/security.c

···
 	return call_int_hook(inode_getattr, 0, path);
 }
 
-int security_inode_setxattr(struct user_namespace *mnt_userns,
+int security_inode_setxattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry, const char *name,
 			    const void *value, size_t size, int flags)
 {
···
 	 * SELinux and Smack integrate the cap call,
 	 * so assume that all LSMs supplying this call do so.
 	 */
-	ret = call_int_hook(inode_setxattr, 1, mnt_userns, dentry, name, value,
+	ret = call_int_hook(inode_setxattr, 1, idmap, dentry, name, value,
 			    size, flags);
 
 	if (ret == 1)
···
 	ret = ima_inode_setxattr(dentry, name, value, size);
 	if (ret)
 		return ret;
-	return evm_inode_setxattr(mnt_userns, dentry, name, value, size);
+	return evm_inode_setxattr(idmap, dentry, name, value, size);
 }
 
 int security_inode_set_acl(struct user_namespace *mnt_userns,
···
 	return call_int_hook(inode_listxattr, 0, dentry);
 }
 
-int security_inode_removexattr(struct user_namespace *mnt_userns,
+int security_inode_removexattr(struct mnt_idmap *idmap,
 			       struct dentry *dentry, const char *name)
 {
 	int ret;
···
 	 * SELinux and Smack integrate the cap call,
 	 * so assume that all LSMs supplying this call do so.
 	 */
-	ret = call_int_hook(inode_removexattr, 1, mnt_userns, dentry, name);
+	ret = call_int_hook(inode_removexattr, 1, idmap, dentry, name);
 	if (ret == 1)
-		ret = cap_inode_removexattr(mnt_userns, dentry, name);
+		ret = cap_inode_removexattr(idmap, dentry, name);
 	if (ret)
 		return ret;
 	ret = ima_inode_removexattr(dentry, name);
 	if (ret)
 		return ret;
-	return evm_inode_removexattr(mnt_userns, dentry, name);
+	return evm_inode_removexattr(idmap, dentry, name);
 }
 
 int security_inode_need_killpriv(struct dentry *dentry)
···
 	return call_int_hook(inode_need_killpriv, 0, dentry);
 }
 
-int security_inode_killpriv(struct user_namespace *mnt_userns,
+int security_inode_killpriv(struct mnt_idmap *idmap,
 			    struct dentry *dentry)
 {
-	return call_int_hook(inode_killpriv, 0, mnt_userns, dentry);
+	return call_int_hook(inode_killpriv, 0, idmap, dentry);
 }
 
 int security_inode_getsecurity(struct mnt_idmap *idmap,

security/selinux/hooks.c

···
 	return true;
 }
 
-static int selinux_inode_setxattr(struct user_namespace *mnt_userns,
+static int selinux_inode_setxattr(struct mnt_idmap *idmap,
 				  struct dentry *dentry, const char *name,
 				  const void *value, size_t size, int flags)
 {
···
 	struct superblock_security_struct *sbsec;
 	struct common_audit_data ad;
 	u32 newsid, sid = current_sid();
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	int rc = 0;
 
 	if (strcmp(name, XATTR_NAME_SELINUX)) {
···
 	return dentry_has_perm(cred, dentry, FILE__GETATTR);
 }
 
-static int selinux_inode_removexattr(struct user_namespace *mnt_userns,
+static int selinux_inode_removexattr(struct mnt_idmap *idmap,
 				     struct dentry *dentry, const char *name)
 {
 	if (strcmp(name, XATTR_NAME_SELINUX)) {
-		int rc = cap_inode_removexattr(mnt_userns, dentry, name);
+		int rc = cap_inode_removexattr(idmap, dentry, name);
 		if (rc)
 			return rc;
 
···
  */
 static int selinux_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
 {
-	return __vfs_setxattr_noperm(&init_user_ns, dentry, XATTR_NAME_SELINUX,
+	return __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_SELINUX,
 				     ctx, ctxlen, 0);
 }
 

security/smack/smack_lsm.c

···
 
 /**
  * smack_inode_setxattr - Smack check for setting xattrs
- * @mnt_userns: active user namespace
+ * @idmap: idmap of the mount
  * @dentry: the object
  * @name: name of the attribute
  * @value: value of the attribute
···
  *
  * Returns 0 if access is permitted, an error code otherwise
  */
-static int smack_inode_setxattr(struct user_namespace *mnt_userns,
+static int smack_inode_setxattr(struct mnt_idmap *idmap,
 				struct dentry *dentry, const char *name,
 				const void *value, size_t size, int flags)
 {
···
 
 /**
  * smack_inode_removexattr - Smack check on removexattr
- * @mnt_userns: active user namespace
+ * @idmap: idmap of the mount
  * @dentry: the object
  * @name: name of the attribute
  *
···
  *
  * Returns 0 if access is permitted, an error code otherwise
  */
-static int smack_inode_removexattr(struct user_namespace *mnt_userns,
+static int smack_inode_removexattr(struct mnt_idmap *idmap,
 				   struct dentry *dentry, const char *name)
 {
 	struct inode_smack *isp;
···
 		if (!smack_privileged(CAP_MAC_ADMIN))
 			rc = -EPERM;
 	} else
-		rc = cap_inode_removexattr(mnt_userns, dentry, name);
+		rc = cap_inode_removexattr(idmap, dentry, name);
 
 	if (rc != 0)
 		return rc;
···
 			 */
 			if (isp->smk_flags & SMK_INODE_CHANGED) {
 				isp->smk_flags &= ~SMK_INODE_CHANGED;
-				rc = __vfs_setxattr(&init_user_ns, dp, inode,
+				rc = __vfs_setxattr(&nop_mnt_idmap, dp, inode,
 					XATTR_NAME_SMACKTRANSMUTE,
 					TRANS_TRUE, TRANS_TRUE_SIZE,
 					0);
···
 
 static int smack_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
 {
-	return __vfs_setxattr_noperm(&init_user_ns, dentry, XATTR_NAME_SMACK,
+	return __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_SMACK,
 				     ctx, ctxlen, 0);
 }