linux-kernel - [PATCH -v2 5/7] module: Extend the MODULE

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Message-ID: <20241202150810.496784892@infradead.org>
Date: Mon, 02 Dec 2024 15:59:51 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: mcgrof@...nel.org
Cc: x86@...nel.org,
 hpa@...or.com,
 petr.pavlu@...e.com,
 samitolvanen@...gle.com,
 da.gomez@...sung.com,
 masahiroy@...nel.org,
 nathan@...nel.org,
 nicolas@...sle.eu,
 linux-kernel@...r.kernel.org,
 linux-modules@...r.kernel.org,
 linux-kbuild@...r.kernel.org,
 hch@...radead.org,
 gregkh@...uxfoundation.org,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [PATCH -v2 5/7] module: Extend the MODULE_ namespace parsing

Instead of only accepting "MODULE_${name}", extend it with a comma
separated list of module names and add tail glob support.

That is, something like: "MODULE_foo-*,bar" is now possible.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/module/main.c  |   39 ++++++++++++++++++++++++++++++++++-----
 scripts/mod/modpost.c |   40 ++++++++++++++++++++++++++++++++++------
 2 files changed, 68 insertions(+), 11 deletions(-)

--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1061,6 +1061,38 @@ static char *get_modinfo(const struct lo
 	return get_next_modinfo(info, tag, NULL);
 }
 
+/*
+ * @namespace ~= "MODULE_foo-*,bar", match @modname to 'foo-*' or 'bar'
+ */
+static bool verify_module_namespace(const char *namespace, const char *modname)
+{
+	size_t len, modlen = strlen(modname);
+	const char *sep;
+	bool glob;
+
+	if (strncmp(namespace, "MODULE_", 7) != 0)
+		return false;
+
+	for (namespace += 7; *namespace; namespace = sep) {
+		sep = strchrnul(namespace, ',');
+		len = sep - namespace;
+
+		glob = false;
+		if (sep[-1] == '*') {
+			len--;
+			glob = true;
+		}
+
+		if (*sep)
+			sep++;
+
+		if (strncmp(namespace, modname, len) == 0 && (glob || len == modlen))
+			return true;
+	}
+
+	return false;
+}
+
 static int verify_namespace_is_imported(const struct load_info *info,
 					const struct kernel_symbol *sym,
 					struct module *mod)
@@ -1070,11 +1102,8 @@ static int verify_namespace_is_imported(
 
 	namespace = kernel_symbol_namespace(sym);
 	if (namespace && namespace[0]) {
-		/*
-		 * Implicitly import MODULE_${mod->name} namespace.
-		 */
-		if (strncmp(namespace, "MODULE_", 7) == 0 &&
-		    strcmp(namespace+7, mod->name) == 0)
+
+		if (verify_module_namespace(namespace, mod->name))
 			return 0;
 
 		for_each_modinfo_entry(imported_namespace, info, "import_ns") {
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1565,7 +1565,6 @@ static const char *mod_basename(const ch
 
 static void read_symbols(const char *modname)
 {
-	char module_namespace[MODULE_NAME_LEN + 8];
 	const char *symname;
 	char *version;
 	char *license;
@@ -1601,10 +1600,6 @@ static void read_symbols(const char *mod
 		     namespace = get_next_modinfo(&info, "import_ns", namespace))
 			add_namespace(&mod->imported_namespaces, namespace);
 
-		snprintf(module_namespace, sizeof(module_namespace), "MODULE_%s",
-			 mod_basename(mod->name));
-		add_namespace(&mod->imported_namespaces, module_namespace);
-
 		if (extra_warn && !get_modinfo(&info, "description"))
 			warn("missing MODULE_DESCRIPTION() in %s\n", modname);
 	}
@@ -1687,6 +1682,38 @@ void buf_write(struct buffer *buf, const
 	buf->pos += len;
 }
 
+/*
+ * @namespace ~= "MODULE_foo-*,bar", match @modname to 'foo-*' or 'bar'
+ */
+static bool module_namespace(const char *namespace, const char *modname)
+{
+	size_t len, modlen = strlen(modname);
+	const char *sep;
+	bool glob;
+
+	if (strncmp(namespace, "MODULE_", 7) != 0)
+		return false;
+
+	for (namespace += 7; *namespace; namespace = sep) {
+		sep = strchrnul(namespace, ',');
+		len = sep - namespace;
+
+		glob = false;
+		if (sep[-1] == '*') {
+			len--;
+			glob = true;
+		}
+
+		if (*sep)
+			sep++;
+
+		if (strncmp(namespace, modname, len) == 0 && (glob || len == modlen))
+			return true;
+	}
+
+	return false;
+}
+
 static void check_exports(struct module *mod)
 {
 	struct symbol *s, *exp;
@@ -1714,7 +1741,8 @@ static void check_exports(struct module
 
 		basename = mod_basename(mod->name);
 
-		if (!contains_namespace(&mod->imported_namespaces, exp->namespace)) {
+		if (!module_namespace(exp->namespace, basename) &&
+		    !contains_namespace(&mod->imported_namespaces, exp->namespace)) {
 			modpost_log(!allow_missing_ns_imports,
 				    "module %s uses symbol %s from namespace %s, but does not import it.\n",
 				    basename, exp->name, exp->namespace);