1 files changed, 31 insertions, 34 deletions

diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index 1115c22deca0..f42488c01957 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -59,6 +59,7 @@ enum ovl_opt {
 	Opt_metacopy,
 	Opt_verity,
 	Opt_volatile,
+	Opt_override_creds,
 };
 
 static const struct constant_table ovl_parameter_bool[] = {
@@ -155,6 +156,7 @@ const struct fs_parameter_spec ovl_parameter_spec[] = {
 	fsparam_enum("metacopy",            Opt_metacopy, ovl_parameter_bool),
 	fsparam_enum("verity",              Opt_verity, ovl_parameter_verity),
 	fsparam_flag("volatile",            Opt_volatile),
+	fsparam_flag_no("override_creds",   Opt_override_creds),
 	{}
 };
 
@@ -662,6 +664,29 @@ static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param)
 	case Opt_userxattr:
 		config->userxattr = true;
 		break;
+	case Opt_override_creds: {
+		const struct cred *cred = NULL;
+
+		if (result.negated) {
+			swap(cred, ofs->creator_cred);
+			put_cred(cred);
+			break;
+		}
+
+		if (!current_in_userns(fc->user_ns)) {
+			err = -EINVAL;
+			break;
+		}
+
+		cred = prepare_creds();
+		if (cred)
+			swap(cred, ofs->creator_cred);
+		else
+			err = -ENOMEM;
+
+		put_cred(cred);
+		break;
+	}
 	default:
 		pr_err("unrecognized mount option \"%s\" or missing value\n",
 		       param->key);
@@ -846,18 +871,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 		config->uuid = OVL_UUID_NULL;
 	}
 
-	/* Resolve verity -> metacopy dependency */
-	if (config->verity_mode && !config->metacopy) {
-		/* Don't allow explicit specified conflicting combinations */
-		if (set.metacopy) {
-			pr_err("conflicting options: metacopy=off,verity=%s\n",
-			       ovl_verity_mode(config));
-			return -EINVAL;
-		}
-		/* Otherwise automatically enable metacopy. */
-		config->metacopy = true;
-	}
-
 	/*
 	 * This is to make the logic below simpler.  It doesn't make any other
 	 * difference, since redirect_dir=on is only used for upper.
@@ -865,18 +878,13 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 	if (!config->upperdir && config->redirect_mode == OVL_REDIRECT_FOLLOW)
 		config->redirect_mode = OVL_REDIRECT_ON;
 
-	/* Resolve verity -> metacopy -> redirect_dir dependency */
+	/* metacopy -> redirect_dir dependency */
 	if (config->metacopy && config->redirect_mode != OVL_REDIRECT_ON) {
 		if (set.metacopy && set.redirect) {
 			pr_err("conflicting options: metacopy=on,redirect_dir=%s\n",
 			       ovl_redirect_mode(config));
 			return -EINVAL;
 		}
-		if (config->verity_mode && set.redirect) {
-			pr_err("conflicting options: verity=%s,redirect_dir=%s\n",
-			       ovl_verity_mode(config), ovl_redirect_mode(config));
-			return -EINVAL;
-		}
 		if (set.redirect) {
 			/*
 			 * There was an explicit redirect_dir=... that resulted
@@ -945,7 +953,7 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 	}
 
 
-	/* Resolve userxattr -> !redirect && !metacopy && !verity dependency */
+	/* Resolve userxattr -> !redirect && !metacopy dependency */
 	if (config->userxattr) {
 		if (set.redirect &&
 		    config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
@@ -957,11 +965,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 			pr_err("conflicting options: userxattr,metacopy=on\n");
 			return -EINVAL;
 		}
-		if (config->verity_mode) {
-			pr_err("conflicting options: userxattr,verity=%s\n",
-			       ovl_verity_mode(config));
-			return -EINVAL;
-		}
 		/*
 		 * Silently disable default setting of redirect and metacopy.
 		 * This shall be the default in the future as well: these
@@ -1000,11 +1003,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 		 */
 	}
 
-	if (ctx->nr_data > 0 && !config->metacopy) {
-		pr_err("lower data-only dirs require metacopy support.\n");
-		return -EINVAL;
-	}
-
 	return 0;
 }
 
@@ -1053,17 +1051,16 @@ int ovl_show_options(struct seq_file *m, struct dentry *dentry)
 		seq_printf(m, ",redirect_dir=%s",
 			   ovl_redirect_mode(&ofs->config));
 	if (ofs->config.index != ovl_index_def)
-		seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
+		seq_printf(m, ",index=%s", str_on_off(ofs->config.index));
 	if (ofs->config.uuid != ovl_uuid_def())
 		seq_printf(m, ",uuid=%s", ovl_uuid_mode(&ofs->config));
 	if (ofs->config.nfs_export != ovl_nfs_export_def)
-		seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
-						"on" : "off");
+		seq_printf(m, ",nfs_export=%s",
+			   str_on_off(ofs->config.nfs_export));
 	if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(ofs))
 		seq_printf(m, ",xino=%s", ovl_xino_mode(&ofs->config));
 	if (ofs->config.metacopy != ovl_metacopy_def)
-		seq_printf(m, ",metacopy=%s",
-			   ofs->config.metacopy ? "on" : "off");
+		seq_printf(m, ",metacopy=%s", str_on_off(ofs->config.metacopy));
 	if (ofs->config.ovl_volatile)
 		seq_puts(m, ",volatile");
 	if (ofs->config.userxattr)