Merge branch 'ovl-fixes' of https://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs.gitfs-current

1 files changed, 71 insertions, 20 deletions

diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index 5a15e5478a6b..d1ca4a9094f2 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -107,21 +107,40 @@ static int ovl_xino_def(void)
 const struct constant_table ovl_parameter_redirect_dir[] = {
 	{ "off",	OVL_REDIRECT_OFF      },
 	{ "follow",	OVL_REDIRECT_FOLLOW   },
+	{ "followdata",	OVL_REDIRECT_FOLLOWDATA },
 	{ "nofollow",	OVL_REDIRECT_NOFOLLOW },
 	{ "on",		OVL_REDIRECT_ON       },
 	{}
 };
 
-static const char *ovl_redirect_mode(struct ovl_config *config)
+static const char *ovl_redirect_mode_name(int redirect_mode)
 {
-	return ovl_parameter_redirect_dir[config->redirect_mode].name;
+	return ovl_parameter_redirect_dir[redirect_mode].name;
 }
 
+const char *ovl_redirect_mode(struct ovl_config *config)
+{
+	return ovl_redirect_mode_name(config->redirect_mode);
+}
+
+int ovl_redirect_follow_mode(bool follow_lower, size_t nr_data)
+{
+	if (ovl_redirect_always_follow && follow_lower)
+		return OVL_REDIRECT_FOLLOW;
+
+	/* Data-only layers cannot be used without following redirects to them */
+	return nr_data ? OVL_REDIRECT_FOLLOWDATA : OVL_REDIRECT_NOFOLLOW;
+}
+
+/*
+ * The default for show_options() is resolved as if there are no data-only layers,
+ * so that redirect_dir=followdata, which is auto selected with data-only layers,
+ * is displayed in mount options.
+ */
 static int ovl_redirect_mode_def(void)
 {
-	return ovl_redirect_dir_def	  ? OVL_REDIRECT_ON :
-	       ovl_redirect_always_follow ? OVL_REDIRECT_FOLLOW :
-					    OVL_REDIRECT_NOFOLLOW;
+	return ovl_redirect_dir_def ? OVL_REDIRECT_ON :
+				      ovl_redirect_follow_mode(true, 0);
 }
 
 static const struct constant_table ovl_parameter_verity[] = {
@@ -659,11 +678,6 @@ static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		break;
 	case Opt_redirect_dir:
 		config->redirect_mode = result.uint_32;
-		if (config->redirect_mode == OVL_REDIRECT_OFF) {
-			config->redirect_mode = ovl_redirect_always_follow ?
-						OVL_REDIRECT_FOLLOW :
-						OVL_REDIRECT_NOFOLLOW;
-		}
 		ctx->set.redirect = true;
 		break;
 	case Opt_index:
@@ -819,7 +833,13 @@ int ovl_init_fs_context(struct fs_context *fc)
 	if (!ofs)
 		goto out_err;
 
-	ofs->config.redirect_mode	= ovl_redirect_mode_def();
+	/*
+	 * The module default determines only if new redirects are created in
+	 * upper dir.  If they are not, the redirect follow mode will be
+	 * determined after parsing mount options.
+	 */
+	ofs->config.redirect_mode	= ovl_redirect_dir_def ?
+					  OVL_REDIRECT_ON : OVL_REDIRECT_OFF;
 	ofs->config.index		= ovl_index_def;
 	ofs->config.uuid		= ovl_uuid_def();
 	ofs->config.nfs_export		= ovl_nfs_export_def;
@@ -845,15 +865,12 @@ void ovl_free_fs(struct ovl_fs *ofs)
 	struct vfsmount **mounts;
 	unsigned i;
 
+	ovl_inuse_unlock_all(ofs);
 	iput(ofs->workbasedir_trap);
 	iput(ofs->workdir_trap);
 	dput(ofs->whiteout);
 	dput(ofs->workdir);
-	if (ofs->workdir_locked)
-		ovl_inuse_unlock(ofs->workbasedir);
 	dput(ofs->workbasedir);
-	if (ofs->upperdir_locked)
-		ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root);
 
 	/* Reuse ofs->config.lowerdirs as a vfsmount array before freeing it */
 	mounts = (struct vfsmount **) ofs->config.lowerdirs;
@@ -880,6 +897,11 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 			 struct ovl_config *config)
 {
 	struct ovl_opt_set set = ctx->set;
+	/* The requested redirect_dir=, for reporting conflicts with it */
+	int redirect_opt = config->redirect_mode;
+	/* The redirect follow mode for redirect_dir=off and for the default */
+	int follow_mode = ovl_redirect_follow_mode(!config->userxattr,
+						   ctx->nr_data);
 
 	/* Workdir/index are useless in non-upper mount */
 	if (!config->upperdir) {
@@ -907,6 +929,13 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 	}
 
 	/*
+	 * Resolve redirect_dir=off to the default redirect follow mode.
+	 * With userxattr, redirects are not followed to lower by default.
+	 */
+	if (config->redirect_mode == OVL_REDIRECT_OFF)
+		config->redirect_mode = follow_mode;
+
+	/*
 	 * This is to make the logic below simpler.  It doesn't make any other
 	 * difference, since redirect_dir=on is only used for upper.
 	 */
@@ -917,7 +946,7 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 	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));
+			       ovl_redirect_mode_name(redirect_opt));
 			return -EINVAL;
 		}
 		if (set.redirect) {
@@ -926,7 +955,7 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 			 * in this conflict.
 			 */
 			pr_info("disabling metacopy due to redirect_dir=%s\n",
-				ovl_redirect_mode(config));
+				ovl_redirect_mode_name(redirect_opt));
 			config->metacopy = false;
 		} else {
 			/* Automatically enable redirect otherwise. */
@@ -934,6 +963,16 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 		}
 	}
 
+	/* Resolve nfs_export -> !data-only layers dependency */
+	if (config->nfs_export && ctx->nr_data) {
+		if (set.nfs_export) {
+			pr_err("NFS export is not supported with data-only layers\n");
+			return -EINVAL;
+		}
+		pr_info("disabling nfs_export due to data-only layers\n");
+		config->nfs_export = false;
+	}
+
 	/* Resolve nfs_export -> index dependency */
 	if (config->nfs_export && !config->index) {
 		if (!config->upperdir &&
@@ -991,9 +1030,10 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 	/* Resolve userxattr -> !redirect && !metacopy dependency */
 	if (config->userxattr) {
 		if (set.redirect &&
-		    config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
+		    config->redirect_mode != OVL_REDIRECT_NOFOLLOW &&
+		    config->redirect_mode != OVL_REDIRECT_FOLLOWDATA) {
 			pr_err("conflicting options: userxattr,redirect_dir=%s\n",
-			       ovl_redirect_mode(config));
+			       ovl_redirect_mode_name(redirect_opt));
 			return -EINVAL;
 		}
 		if (config->metacopy && set.metacopy) {
@@ -1006,10 +1046,21 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
 		 * options must be explicitly enabled if used together with
 		 * userxattr.
 		 */
-		config->redirect_mode = OVL_REDIRECT_NOFOLLOW;
+		if (!set.redirect)
+			config->redirect_mode = follow_mode;
 		config->metacopy = false;
 	}
 
+	/* Data-only layers are reached through redirects */
+	if (ctx->nr_data && config->redirect_mode == OVL_REDIRECT_NOFOLLOW) {
+		pr_err("redirect_dir=nofollow is not supported with data-only layers\n");
+		return -EINVAL;
+	}
+	if (!ctx->nr_data && config->redirect_mode == OVL_REDIRECT_FOLLOWDATA) {
+		pr_err("redirect_dir=followdata requires data-only layers\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * Fail if we don't have trusted xattr capability and a feature was
 	 * explicitly requested that requires them.