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

Pull overlayfs fixes from Miklos Szeredi:
 "Fix regressions:

   - missing CONFIG_EXPORTFS dependency

   - failure if upper fs doesn't support xattr

   - bad error cleanup

  This also adds the concept of "impure" directories complementing the
  "origin" marking introduced in -rc1. Together they enable getting
  consistent st_ino and d_ino for directory listings.

  And there's a bug fix and a cleanup as well"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: filter trusted xattr for non-admin
  ovl: mark upper merge dir with type origin entries "impure"
  ovl: mark upper dir with type origin entries "impure"
  ovl: remove unused arg from ovl_lookup_temp()
  ovl: handle rename when upper doesn't support xattr
  ovl: don't fail copy-up if upper doesn't support xattr
  ovl: check on mount time if upper fs supports setting xattr
  ovl: fix creds leak in copy up error path
  ovl: select EXPORTFS

9 files changed, 178 insertions, 44 deletions

diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
index 0daac5112f7a..c0c9683934b7 100644
--- a/fs/overlayfs/Kconfig
+++ b/fs/overlayfs/Kconfig
@@ -1,5 +1,6 @@
 config OVERLAY_FS
         tristate "Overlay filesystem support"
+        select EXPORTFS
         help
           An overlay filesystem combines two filesystems - an 'upper' filesystem
           and a 'lower' filesystem.  When a name exists in both filesystems, the
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 9008ab9fbd2e..7a44533f4bbf 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -300,7 +300,11 @@ static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
                         return PTR_ERR(fh);
         }
 
-        err = ovl_do_setxattr(upper, OVL_XATTR_ORIGIN, fh, fh ? fh->len : 0, 0);
+        /*
+         * Do not fail when upper doesn't support xattrs.
+         */
+        err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
+                                 fh ? fh->len : 0, 0);
         kfree(fh);
 
         return err;
@@ -342,13 +346,14 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
         if (tmpfile)
                 temp = ovl_do_tmpfile(upperdir, stat->mode);
         else
-                temp = ovl_lookup_temp(workdir, dentry);
-        err = PTR_ERR(temp);
-        if (IS_ERR(temp))
-                goto out1;
-
+                temp = ovl_lookup_temp(workdir);
         err = 0;
-        if (!tmpfile)
+        if (IS_ERR(temp)) {
+                err = PTR_ERR(temp);
+                temp = NULL;
+        }
+
+        if (!err && !tmpfile)
                 err = ovl_create_real(wdir, temp, &cattr, NULL, true);
 
         if (new_creds) {
@@ -454,6 +459,11 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
         ovl_path_upper(parent, &parentpath);
         upperdir = parentpath.dentry;
 
+        /* Mark parent "impure" because it may now contain non-pure upper */
+        err = ovl_set_impure(parent, upperdir);
+        if (err)
+                return err;
+
         err = vfs_getattr(&parentpath, &pstat,
                           STATX_ATIME | STATX_MTIME, AT_STATX_SYNC_AS_STAT);
         if (err)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 723b98b90698..a63a71656e9b 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -41,7 +41,7 @@ void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
         }
 }
 
-struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
+struct dentry *ovl_lookup_temp(struct dentry *workdir)
 {
         struct dentry *temp;
         char name[20];
@@ -68,7 +68,7 @@ static struct dentry *ovl_whiteout(struct dentry *workdir,
         struct dentry *whiteout;
         struct inode *wdir = workdir->d_inode;
 
-        whiteout = ovl_lookup_temp(workdir, dentry);
+        whiteout = ovl_lookup_temp(workdir);
         if (IS_ERR(whiteout))
                 return whiteout;
 
@@ -127,17 +127,28 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
         return err;
 }
 
-static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
+static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
+                               int xerr)
 {
         int err;
 
-        err = ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
+        err = ovl_check_setxattr(dentry, upper, OVL_XATTR_OPAQUE, "y", 1, xerr);
         if (!err)
                 ovl_dentry_set_opaque(dentry);
 
         return err;
 }
 
+static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
+{
+        /*
+         * Fail with -EIO when trying to create opaque dir and upper doesn't
+         * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to
+         * return a specific error for noxattr case.
+         */
+        return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
+}
+
 /* Common operations required to be done after creation of file on upper */
 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
                             struct dentry *newdentry, bool hardlink)
@@ -162,6 +173,11 @@ static bool ovl_type_merge(struct dentry *dentry)
         return OVL_TYPE_MERGE(ovl_path_type(dentry));
 }
 
+static bool ovl_type_origin(struct dentry *dentry)
+{
+        return OVL_TYPE_ORIGIN(ovl_path_type(dentry));
+}
+
 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
                             struct cattr *attr, struct dentry *hardlink)
 {
@@ -250,7 +266,7 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
         if (upper->d_parent->d_inode != udir)
                 goto out_unlock;
 
-        opaquedir = ovl_lookup_temp(workdir, dentry);
+        opaquedir = ovl_lookup_temp(workdir);
         err = PTR_ERR(opaquedir);
         if (IS_ERR(opaquedir))
                 goto out_unlock;
@@ -382,7 +398,7 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
         if (err)
                 goto out;
 
-        newdentry = ovl_lookup_temp(workdir, dentry);
+        newdentry = ovl_lookup_temp(workdir);
         err = PTR_ERR(newdentry);
         if (IS_ERR(newdentry))
                 goto out_unlock;
@@ -846,18 +862,16 @@ static int ovl_set_redirect(struct dentry *dentry, bool samedir)
         if (IS_ERR(redirect))
                 return PTR_ERR(redirect);
 
-        err = ovl_do_setxattr(ovl_dentry_upper(dentry), OVL_XATTR_REDIRECT,
-                              redirect, strlen(redirect), 0);
+        err = ovl_check_setxattr(dentry, ovl_dentry_upper(dentry),
+                                 OVL_XATTR_REDIRECT,
+                                 redirect, strlen(redirect), -EXDEV);
         if (!err) {
                 spin_lock(&dentry->d_lock);
                 ovl_dentry_set_redirect(dentry, redirect);
                 spin_unlock(&dentry->d_lock);
         } else {
                 kfree(redirect);
-                if (err == -EOPNOTSUPP)
-                        ovl_clear_redirect_dir(dentry->d_sb);
-                else
-                        pr_warn_ratelimited("overlay: failed to set redirect (%i)\n", err);
+                pr_warn_ratelimited("overlay: failed to set redirect (%i)\n", err);
                 /* Fall back to userspace copy-up */
                 err = -EXDEV;
         }
@@ -943,6 +957,25 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
         old_upperdir = ovl_dentry_upper(old->d_parent);
         new_upperdir = ovl_dentry_upper(new->d_parent);