ovl: generalize ovl_verify_origin() and helpers

Remove the "origin" language from the functions that handle set, get
and verify of "origin" xattr and pass the xattr name as an argument.

The same helpers are going to be used for NFS export to get, get and
verify the "upper" xattr for directory index entries.

ovl_verify_origin() is now a helper used only to verify non upper
file handle stored in "origin" xattr of upper inode.

The upper root dir file handle is still stored in "origin" xattr on
the index dir for backward compatibility. This is going to be changed
by the patch that adds directory index entries support.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

4 files changed, 38 insertions, 30 deletions

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 206ecec..503c924 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -232,13 +232,13 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 	return err;
 }
 
-struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
+struct ovl_fh *ovl_encode_fh(struct dentry *real, bool is_upper)
 {
 	struct ovl_fh *fh;
 	int fh_type, fh_len, dwords;
 	void *buf;
 	int buflen = MAX_HANDLE_SZ;
-	uuid_t *uuid = &lower->d_sb->s_uuid;
+	uuid_t *uuid = &real->d_sb->s_uuid;
 
 	buf = kmalloc(buflen, GFP_KERNEL);
 	if (!buf)
@@ -250,7 +250,7 @@ struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
 	 * the price or reconnecting the dentry.
 	 */
 	dwords = buflen >> 2;
-	fh_type = exportfs_encode_fh(lower, buf, &dwords, 0);
+	fh_type = exportfs_encode_fh(real, buf, &dwords, 0);
 	buflen = (dwords << 2);
 
 	fh = ERR_PTR(-EIO);
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 27f25a6..11e164c 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -114,12 +114,12 @@ static int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
 	return 0;
 }
 
-static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
+static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
 {
 	int res, err;
 	struct ovl_fh *fh = NULL;
 
-	res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
+	res = vfs_getxattr(dentry, name, NULL, 0);
 	if (res < 0) {
 		if (res == -ENODATA || res == -EOPNOTSUPP)
 			return NULL;
@@ -133,7 +133,7 @@ static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry)
 	if (!fh)
 		return ERR_PTR(-ENOMEM);
 
-	res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, fh, res);
+	res = vfs_getxattr(dentry, name, fh, res);
 	if (res < 0)
 		goto fail;
 
@@ -337,7 +337,7 @@ invalid:
 static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
 			    struct ovl_path **stackp, unsigned int *ctrp)
 {
-	struct ovl_fh *fh = ovl_get_origin_fh(upperdentry);
+	struct ovl_fh *fh = ovl_get_fh(upperdentry, OVL_XATTR_ORIGIN);
 	int err;
 
 	if (IS_ERR_OR_NULL(fh))
@@ -360,12 +360,13 @@ static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
 }
 
 /*
- * Verify that @fh matches the origin file handle stored in OVL_XATTR_ORIGIN.
+ * Verify that @fh matches the file handle stored in xattr @name.
  * Return 0 on match, -ESTALE on mismatch, < 0 on error.
  */
-static int ovl_verify_origin_fh(struct dentry *dentry, const struct ovl_fh *fh)
+static int ovl_verify_fh(struct dentry *dentry, const char *name,
+			 const struct ovl_fh *fh)
 {
-	struct ovl_fh *ofh = ovl_get_origin_fh(dentry);
+	struct ovl_fh *ofh = ovl_get_fh(dentry, name);
 	int err = 0;
 
 	if (!ofh)
@@ -382,28 +383,28 @@ static int ovl_verify_origin_fh(struct dentry *dentry, const struct ovl_fh *fh)
 }
 
 /*
- * Verify that an inode matches the origin file handle stored in upper inode.
+ * Verify that @real dentry matches the file handle stored in xattr @name.
  *
- * If @set is true and there is no stored file handle, encode and store origin
- * file handle in OVL_XATTR_ORIGIN.
+ * If @set is true and there is no stored file handle, encode @real and store
+ * file handle in xattr @name.
  *
- * Return 0 on match, -ESTALE on mismatch, < 0 on error.
+ * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error.
  */
-int ovl_verify_origin(struct dentry *dentry, struct dentry *origin,
-		      bool is_upper, bool set)
+int ovl_verify_set_fh(struct dentry *dentry, const char *name,
+		      struct dentry *real, bool is_upper, bool set)
 {
 	struct inode *inode;
 	struct ovl_fh *fh;
 	int err;
 
-	fh = ovl_encode_fh(origin, is_upper);
+	fh = ovl_encode_fh(real, is_upper);
 	err = PTR_ERR(fh);
 	if (IS_ERR(fh))
 		goto fail;
 
-	err = ovl_verify_origin_fh(dentry, fh);
+	err = ovl_verify_fh(dentry, name, fh);
 	if (set && err == -ENODATA)
-		err = ovl_do_setxattr(dentry, OVL_XATTR_ORIGIN, fh, fh->len, 0);
+		err = ovl_do_setxattr(dentry, name, fh, fh->len, 0);
 	if (err)
 		goto fail;
 
@@ -412,9 +413,10 @@ out:
 	return err;
 
 fail:
-	inode = d_inode(origin);
-	pr_warn_ratelimited("overlayfs: failed to verify origin (%pd2, ino=%lu, err=%i)\n",
-			    origin, inode ? inode->i_ino : 0, err);
+	inode = d_inode(real);
+	pr_warn_ratelimited("overlayfs: failed to verify %s (%pd2, ino=%lu, err=%i)\n",
+			    is_upper ? "upper" : "origin", real,
+			    inode ? inode->i_ino : 0, err);
 	goto out;
 }
 
@@ -466,7 +468,7 @@ int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
 	if (err)
 		goto fail;
 
-	err = ovl_verify_origin_fh(index, fh);
+	err = ovl_verify_fh(index, OVL_XATTR_ORIGIN, fh);
 	if (err)
 		goto fail;
 
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index d55afb6..1d62b1e 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -249,8 +249,8 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
 
 
 /* namei.c */
-int ovl_verify_origin(struct dentry *dentry, struct dentry *origin,
-		      bool is_upper, bool set);
+int ovl_verify_set_fh(struct dentry *dentry, const char *name,
+		      struct dentry *real, bool is_upper, bool set);
 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
 int ovl_get_index_name(struct dentry *origin, struct qstr *name);
 int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
@@ -258,6 +258,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			  unsigned int flags);
 bool ovl_lower_positive(struct dentry *dentry);
 
+static inline int ovl_verify_origin(struct dentry *upper,
+				    struct dentry *origin, bool set)
+{
+	return ovl_verify_set_fh(upper, OVL_XATTR_ORIGIN, origin, false, set);
+}
+
 /* readdir.c */
 extern const struct file_operations ovl_dir_operations;
 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
@@ -320,6 +326,6 @@ int ovl_copy_up(struct dentry *dentry);
 int ovl_copy_up_flags(struct dentry *dentry, int flags);
 int ovl_copy_xattr(struct dentry *old, struct dentry *new);
 int ovl_set_attr(struct dentry *upper, struct kstat *stat);
-struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper);
+struct ovl_fh *ovl_encode_fh(struct dentry *real, bool is_upper);
 int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 		   struct dentry *upper);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 4345c3f..4ebbb36 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1041,7 +1041,7 @@ static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
 
 	/* Verify lower root is upper root origin */
 	err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
-				false, true);
+				true);
 	if (err) {
 		pr_err("overlayfs: failed to verify upper root origin\n");
 		goto out;
@@ -1049,9 +1049,9 @@ static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
 
 	ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
 	if (ofs->indexdir) {
-		/* Verify upper root is index dir origin */
-		err = ovl_verify_origin(ofs->indexdir, upperpath->dentry,
-					true, true);
+		/* Verify upper root is exclusively associated with index dir */
+		err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN,
+					upperpath->dentry, true, true);
 		if (err)
 			pr_err("overlayfs: failed to verify index dir origin\n");