ovl: verify index dir matches upper dir

[thirdparty/kernel/linux.git] / fs / overlayfs / copy_up.c

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 42807cb57da07056966afa802801818548b4c857..5e8fd99557e101cfb4e83a32a5001bdcbb62aacb 100644 (file)
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -233,7 +233,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
        return err;
 }
 
-struct ovl_fh *ovl_encode_fh(struct dentry *lower)
+struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
 {
        struct ovl_fh *fh;
        int fh_type, fh_len, dwords;
@@ -272,6 +272,14 @@ struct ovl_fh *ovl_encode_fh(struct dentry *lower)
        fh->magic = OVL_FH_MAGIC;
        fh->type = fh_type;
        fh->flags = OVL_FH_FLAG_CPU_ENDIAN;
+       /*
+        * When we will want to decode an overlay dentry from this handle
+        * and all layers are on the same fs, if we get a disconncted real
+        * dentry when we decode fid, the only way to tell if we should assign
+        * it to upperdentry or to lowerstack is by checking this flag.
+        */
+       if (is_upper)
+               fh->flags |= OVL_FH_FLAG_PATH_UPPER;
        fh->len = fh_len;
        fh->uuid = *uuid;
        memcpy(fh->fid, buf, buflen);
@@ -293,7 +301,7 @@ static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
         * up and a pure upper inode.
         */
        if (ovl_can_decode_fh(lower->d_sb)) {
-               fh = ovl_encode_fh(lower);
+               fh = ovl_encode_fh(lower, false);
                if (IS_ERR(fh))
                        return PTR_ERR(fh);
        }