Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "This fixes a crash with SELinux and several other old and new bugs"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: check for bad and whiteout index on lookup
  ovl: do not cleanup directory and whiteout index entries
  ovl: fix xattr get and set with selinux
  ovl: remove unneeded check for IS_ERR()
  ovl: fix origin verification of index dir
  ovl: mark parent impure on ovl_link()
  ovl: fix random return value on mount

fs/overlayfs/dir.c

@@ -481,17 +481,30 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
 }
 
 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
-			      struct cattr *attr, struct dentry *hardlink)
+			      struct cattr *attr, struct dentry *hardlink,
+			      bool origin)
 {
 	int err;
 	const struct cred *old_cred;
 	struct cred *override_cred;
+	struct dentry *parent = dentry->d_parent;
 
-	err = ovl_copy_up(dentry->d_parent);
+	err = ovl_copy_up(parent);
 	if (err)
 		return err;
 
 	old_cred = ovl_override_creds(dentry->d_sb);
+
+	/*
+	 * When linking a file with copy up origin into a new parent, mark the
+	 * new parent dir "impure".
+	 */
+	if (origin) {
+		err = ovl_set_impure(parent, ovl_dentry_upper(parent));
+		if (err)
+			goto out_revert_creds;
+	}
+
 	err = -ENOMEM;
 	override_cred = prepare_creds();
 	if (override_cred) {
@@ -550,7 +563,7 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 	inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 	attr.mode = inode->i_mode;
 
-	err = ovl_create_or_link(dentry, inode, &attr, NULL);
+	err = ovl_create_or_link(dentry, inode, &attr, NULL, false);
 	if (err)
 		iput(inode);
 
@@ -609,7 +622,8 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
 	inode = d_inode(old);
 	ihold(inode);
 
-	err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old));
+	err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old),
+				 ovl_type_origin(old));
 	if (err)
 		iput(inode);
 

fs/overlayfs/inode.c

@@ -202,37 +202,38 @@ bool ovl_is_private_xattr(const char *name)
 		       sizeof(OVL_XATTR_PREFIX) - 1) == 0;
 }
 
-int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,
-		  size_t size, int flags)
+int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
+		  const void *value, size_t size, int flags)
 {
 	int err;
-	struct path realpath;
-	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
+	struct dentry *upperdentry = ovl_i_dentry_upper(inode);
+	struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
 	const struct cred *old_cred;
 
 	err = ovl_want_write(dentry);
 	if (err)
 		goto out;
 
-	if (!value && !OVL_TYPE_UPPER(type)) {
-		err = vfs_getxattr(realpath.dentry, name, NULL, 0);
+	if (!value && !upperdentry) {
+		err = vfs_getxattr(realdentry, name, NULL, 0);
 		if (err < 0)
 			goto out_drop_write;
 	}
 
+	if (!upperdentry) {
 		err = ovl_copy_up(dentry);
 		if (err)
 			goto out_drop_write;
 
-	if (!OVL_TYPE_UPPER(type))
-		ovl_path_upper(dentry, &realpath);
+		realdentry = ovl_dentry_upper(dentry);
+	}
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	if (value)
-		err = vfs_setxattr(realpath.dentry, name, value, size, flags);
+		err = vfs_setxattr(realdentry, name, value, size, flags);
 	else {
 		WARN_ON(flags != XATTR_REPLACE);
-		err = vfs_removexattr(realpath.dentry, name);
+		err = vfs_removexattr(realdentry, name);
 	}
 	revert_creds(old_cred);
 
@@ -242,12 +243,13 @@ int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,
 	return err;
 }
 
-int ovl_xattr_get(struct dentry *dentry, const char *name,
+int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 		  void *value, size_t size)
 {
-	struct dentry *realdentry = ovl_dentry_real(dentry);
 	ssize_t res;
 	const struct cred *old_cred;
+	struct dentry *realdentry =
+		ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry);
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	res = vfs_getxattr(realdentry, name, value, size);

fs/overlayfs/namei.c

@@ -397,8 +397,19 @@ int ovl_verify_index(struct dentry *index, struct path *lowerstack,
 	if (!d_inode(index))
 		return 0;
 
-	err = -EISDIR;
-	if (d_is_dir(index))
+	/*
+	 * Directory index entries are going to be used for looking up
+	 * redirected upper dirs by lower dir fh when decoding an overlay
+	 * file handle of a merge dir. Whiteout index entries are going to be
+	 * used as an indication that an exported overlay file handle should
+	 * be treated as stale (i.e. after unlink of the overlay inode).
+	 * We don't know the verification rules for directory and whiteout
+	 * index entries, because they have not been implemented yet, so return
+	 * EROFS if those entries are found to avoid corrupting an index that
+	 * was created by a newer kernel.
+	 */
+	err = -EROFS;
+	if (d_is_dir(index) || ovl_is_whiteout(index))
 		goto fail;
 
 	err = -EINVAL;
@@ -436,8 +447,8 @@ int ovl_verify_index(struct dentry *index, struct path *lowerstack,
 	return err;
 
 fail:
-	pr_warn_ratelimited("overlayfs: failed to verify index (%pd2, err=%i)\n",
-			    index, err);
+	pr_warn_ratelimited("overlayfs: failed to verify index (%pd2, ftype=%x, err=%i)\n",
+			    index, d_inode(index)->i_mode & S_IFMT, err);
 	goto out;
 }
 
@@ -502,6 +513,7 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
 		goto out;
 	}
 
+	inode = d_inode(index);
 	if (d_is_negative(index)) {
 		if (upper && d_inode(origin)->i_nlink > 1) {
 			pr_warn_ratelimited("overlayfs: hard link with origin but no index (ino=%lu).\n",
@@ -511,11 +523,22 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry,
 
 		dput(index);
 		index = NULL;
-	} else if (upper && d_inode(index) != d_inode(upper)) {
-		inode = d_inode(index);
-		pr_warn_ratelimited("overlayfs: wrong index found (index ino: %lu, upper ino: %lu).\n",
-				    d_inode(index)->i_ino,
-				    d_inode(upper)->i_ino);
+	} else if (upper && d_inode(upper) != inode) {
+		pr_warn_ratelimited("overlayfs: wrong index found (index=%pd2, ino=%lu, upper ino=%lu).\n",
+				    index, inode->i_ino, d_inode(upper)->i_ino);
+		goto fail;
+	} else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
+		   ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
+		/*
+		 * Index should always be of the same file type as origin
+		 * except for the case of a whiteout index. A whiteout
+		 * index should only exist if all lower aliases have been
+		 * unlinked, which means that finding a lower origin on lookup
+		 * whose index is a whiteout should be treated as an error.
+		 */
+		pr_warn_ratelimited("overlayfs: bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n",
+				    index, d_inode(index)->i_mode & S_IFMT,
+				    d_inode(origin)->i_mode & S_IFMT);
 		goto fail;
 	}
 

fs/overlayfs/overlayfs.h

@@ -47,7 +47,8 @@ enum ovl_flag {
 /* Is the real inode encoded in fid an upper inode? */
 #define OVL_FH_FLAG_PATH_UPPER	(1 << 2)
 
-#define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN)
+#define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
+			 OVL_FH_FLAG_PATH_UPPER)
 
 #if defined(__LITTLE_ENDIAN)
 #define OVL_FH_FLAG_CPU_ENDIAN 0
@@ -199,6 +200,7 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
 struct dentry *ovl_dentry_upper(struct dentry *dentry);
 struct dentry *ovl_dentry_lower(struct dentry *dentry);
 struct dentry *ovl_dentry_real(struct dentry *dentry);
+struct dentry *ovl_i_dentry_upper(struct inode *inode);
 struct inode *ovl_inode_upper(struct inode *inode);
 struct inode *ovl_inode_lower(struct inode *inode);
 struct inode *ovl_inode_real(struct inode *inode);
@@ -270,9 +272,9 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr);
 int ovl_getattr(const struct path *path, struct kstat *stat,
 		u32 request_mask, unsigned int flags);
 int ovl_permission(struct inode *inode, int mask);
-int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,
-		  size_t size, int flags);
-int ovl_xattr_get(struct dentry *dentry, const char *name,
+int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
+		  const void *value, size_t size, int flags);
+int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 		  void *value, size_t size);
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 struct posix_acl *ovl_get_acl(struct inode *inode, int type);

fs/overlayfs/readdir.c

@@ -703,7 +703,10 @@ int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,
 			err = PTR_ERR(index);
 			break;
 		}
-		if (ovl_verify_index(index, lowerstack, numlower)) {
+		err = ovl_verify_index(index, lowerstack, numlower);
+		if (err) {
+			if (err == -EROFS)
+				break;
 			err = ovl_cleanup(dir, index);
 			if (err)
 				break;

fs/overlayfs/super.c

@@ -692,7 +692,7 @@ ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
 			struct dentry *dentry, struct inode *inode,
 			const char *name, void *buffer, size_t size)
 {
-	return ovl_xattr_get(dentry, handler->name, buffer, size);
+	return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
 }
 
 static int __maybe_unused
@@ -742,7 +742,7 @@ ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
 			return err;
 	}
 
-	err = ovl_xattr_set(dentry, handler->name, value, size, flags);
+	err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
 	if (!err)
 		ovl_copyattr(ovl_inode_real(inode), inode);
 
@@ -772,7 +772,7 @@ static int ovl_other_xattr_get(const struct xattr_handler *handler,
 			       struct dentry *dentry, struct inode *inode,
 			       const char *name, void *buffer, size_t size)
 {
-	return ovl_xattr_get(dentry, name, buffer, size);
+	return ovl_xattr_get(dentry, inode, name, buffer, size);
 }
 
 static int ovl_other_xattr_set(const struct xattr_handler *handler,
@@ -780,7 +780,7 @@ static int ovl_other_xattr_set(const struct xattr_handler *handler,
 			       const char *name, const void *value,
 			       size_t size, int flags)
 {
-	return ovl_xattr_set(dentry, name, value, size, flags);
+	return ovl_xattr_set(dentry, inode, name, value, size, flags);
 }
 
 static const struct xattr_handler __maybe_unused
@@ -1058,10 +1058,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 
 		ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry,
 						   OVL_INDEXDIR_NAME, true);
-		err = PTR_ERR(ufs->indexdir);
-		if (IS_ERR(ufs->indexdir))
-			goto out_put_lower_mnt;
-
 		if (ufs->indexdir) {
 			/* Verify upper root is index dir origin */
 			err = ovl_verify_origin(ufs->indexdir, ufs->upper_mnt,
@@ -1090,6 +1086,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	else
 		sb->s_d_op = &ovl_dentry_operations;
 
+	err = -ENOMEM;
 	ufs->creator_cred = cred = prepare_creds();
 	if (!cred)
 		goto out_put_indexdir;

fs/overlayfs/util.c

@@ -157,9 +157,14 @@ struct dentry *ovl_dentry_real(struct dentry *dentry)
 	return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
 }
 
+struct dentry *ovl_i_dentry_upper(struct inode *inode)
+{
+	return ovl_upperdentry_dereference(OVL_I(inode));
+}
+
 struct inode *ovl_inode_upper(struct inode *inode)
 {
-	struct dentry *upperdentry = ovl_upperdentry_dereference(OVL_I(inode));
+	struct dentry *upperdentry = ovl_i_dentry_upper(inode);
 
 	return upperdentry ? d_inode(upperdentry) : NULL;
 }