Merge tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

Pull modules updates from Jessica Yu:
 "The main bulk of this pull request introduces a new exported symbol
  namespaces feature. The number of exported symbols is increasingly
  growing with each release (we're at about 31k exports as of 5.3-rc7)
  and we currently have no way of visualizing how these symbols are
  "clustered" or making sense of this huge export surface.

  Namespacing exported symbols allows kernel developers to more
  explicitly partition and categorize exported symbols, as well as more
  easily limiting the availability of namespaced symbols to other parts
  of the kernel. For starters, we have introduced the USB_STORAGE
  namespace to demonstrate the API's usage. I have briefly summarized
  the feature and its main motivations in the tag below.

  Summary:

   - Introduce exported symbol namespaces.

     This new feature allows subsystem maintainers to partition and
     categorize their exported symbols into explicit namespaces. Module
     authors are now required to import the namespaces they need.

     Some of the main motivations of this feature include: allowing
     kernel developers to better manage the export surface, allow
     subsystem maintainers to explicitly state that usage of some
     exported symbols should only be limited to certain users (think:
     inter-module or inter-driver symbols, debugging symbols, etc), as
     well as more easily limiting the availability of namespaced symbols
     to other parts of the kernel.

     With the module import requirement, it is also easier to spot the
     misuse of exported symbols during patch review.

     Two new macros are introduced: EXPORT_SYMBOL_NS() and
     EXPORT_SYMBOL_NS_GPL(). The API is thoroughly documented in
     Documentation/kbuild/namespaces.rst.

   - Some small code and kbuild cleanups here and there"

* tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  module: Remove leftover '#undef' from export header
  module: remove unneeded casts in cmp_name()
  module: move CONFIG_UNUSED_SYMBOLS to the sub-menu of MODULES
  module: remove redundant 'depends on MODULES'
  module: Fix link failure due to invalid relocation on namespace offset
  usb-storage: export symbols in USB_STORAGE namespace
  usb-storage: remove single-use define for debugging
  docs: Add documentation for Symbol Namespaces
  scripts: Coccinelle script for namespace dependencies.
  modpost: add support for generating namespace dependencies
  export: allow definition default namespaces in Makefiles or sources
  module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
  modpost: add support for symbol namespaces
  module: add support for symbol namespaces.
  export: explicitly align struct kernel_symbol
  module: support reading multiple values per modinfo tag

1 files changed, 69 insertions, 7 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 9ee93421269c..32873bcce738 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -544,12 +544,20 @@ static const char *kernel_symbol_name(const struct kernel_symbol *sym)
 #endif
 }
 
-static int cmp_name(const void *va, const void *vb)
+static const char *kernel_symbol_namespace(const struct kernel_symbol *sym)
 {
-	const char *a;
-	const struct kernel_symbol *b;
-	a = va; b = vb;
-	return strcmp(a, kernel_symbol_name(b));
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+	if (!sym->namespace_offset)
+		return NULL;
+	return offset_to_ptr(&sym->namespace_offset);
+#else
+	return sym->namespace;
+#endif
+}
+
+static int cmp_name(const void *name, const void *sym)
+{
+	return strcmp(name, kernel_symbol_name(sym));
 }
 
 static bool find_exported_symbol_in_section(const struct symsearch *syms,
@@ -1379,6 +1387,41 @@ static inline int same_magic(const char *amagic, const char *bmagic,
 }
 #endif /* CONFIG_MODVERSIONS */
 
+static char *get_modinfo(const struct load_info *info, const char *tag);
+static char *get_next_modinfo(const struct load_info *info, const char *tag,
+			      char *prev);
+
+static int verify_namespace_is_imported(const struct load_info *info,
+					const struct kernel_symbol *sym,
+					struct module *mod)
+{
+	const char *namespace;
+	char *imported_namespace;
+
+	namespace = kernel_symbol_namespace(sym);
+	if (namespace) {
+		imported_namespace = get_modinfo(info, "import_ns");
+		while (imported_namespace) {
+			if (strcmp(namespace, imported_namespace) == 0)
+				return 0;
+			imported_namespace = get_next_modinfo(
+				info, "import_ns", imported_namespace);
+		}
+#ifdef CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
+		pr_warn(
+#else
+		pr_err(
+#endif
+			"%s: module uses symbol (%s) from namespace %s, but does not import it.\n",
+			mod->name, kernel_symbol_name(sym), namespace);
+#ifndef CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
+		return -EINVAL;
+#endif
+	}
+	return 0;
+}
+
+
 /* Resolve a symbol for this module.  I.e. if we find one, record usage. */
 static const struct kernel_symbol *resolve_symbol(struct module *mod,
 						  const struct load_info *info,
@@ -1407,6 +1450,12 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
 		goto getname;
 	}
 
+	err = verify_namespace_is_imported(info, sym, mod);
+	if (err) {
+		sym = ERR_PTR(err);
+		goto getname;
+	}
+
 	err = ref_module(mod, owner);
 	if (err) {
 		sym = ERR_PTR(err);
@@ -2481,7 +2530,8 @@ static char *next_string(char *string, unsigned long *secsize)
 	return string;
 }
 
-static char *get_modinfo(struct load_info *info, const char *tag)
+static char *get_next_modinfo(const struct load_info *info, const char *tag,
+			      char *prev)
 {
 	char *p;
 	unsigned int taglen = strlen(tag);
@@ -2492,13 +2542,25 @@ static char *get_modinfo(struct load_info *info, const char *tag)
 	 * get_modinfo() calls made before rewrite_section_headers()
 	 * must use sh_offset, as sh_addr isn't set!
 	 */
-	for (p = (char *)info->hdr + infosec->sh_offset; p; p = next_string(p, &size)) {
+	char *modinfo = (char *)info->hdr + infosec->sh_offset;
+
+	if (prev) {
+		size -= prev - modinfo;
+		modinfo = next_string(prev, &size);
+	}
+
+	for (p = modinfo; p; p = next_string(p, &size)) {
 		if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
 			return p + taglen + 1;
 	}
 	return NULL;
 }
 
+static char *get_modinfo(const struct load_info *info, const char *tag)
+{
+	return get_next_modinfo(info, tag, NULL);
+}
+
 static void setup_modinfo(struct module *mod, struct load_info *info)
 {
 	struct module_attribute *attr;