linux-kernel - [PATCH v3 6/9] module: Move integrity checks into dedicated function

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Message-Id: <20250429-module-hashes-v3-6-00e9258def9e@weissschuh.net>
Date: Tue, 29 Apr 2025 15:04:33 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Masahiro Yamada <masahiroy@...nel.org>, 
 Nathan Chancellor <nathan@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
 Luis Chamberlain <mcgrof@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>, 
 Sami Tolvanen <samitolvanen@...gle.com>, 
 Daniel Gomez <da.gomez@...sung.com>, Paul Moore <paul@...l-moore.com>, 
 James Morris <jmorris@...ei.org>, "Serge E. Hallyn" <serge@...lyn.com>, 
 Jonathan Corbet <corbet@....net>, Madhavan Srinivasan <maddy@...ux.ibm.com>, 
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>, 
 Christophe Leroy <christophe.leroy@...roup.eu>, 
 Naveen N Rao <naveen@...nel.org>, Mimi Zohar <zohar@...ux.ibm.com>, 
 Roberto Sassu <roberto.sassu@...wei.com>, 
 Dmitry Kasatkin <dmitry.kasatkin@...il.com>, 
 Eric Snowberg <eric.snowberg@...cle.com>, 
 Nicolas Schier <nicolas.schier@...ux.dev>, 
 Nicolas Schier <nicolas.schier@...ux.dev>
Cc: Fabian Grünbichler <f.gruenbichler@...xmox.com>, 
 Arnout Engelen <arnout@...t.net>, Mattia Rizzolo <mattia@...reri.org>, 
 kpcyrd <kpcyrd@...hlinux.org>, Christian Heusel <christian@...sel.eu>, 
 Câju Mihai-Drosi <mcaju95@...il.com>, 
 linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arch@...r.kernel.org, linux-modules@...r.kernel.org, 
 linux-security-module@...r.kernel.org, linux-doc@...r.kernel.org, 
 linuxppc-dev@...ts.ozlabs.org, linux-integrity@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH v3 6/9] module: Move integrity checks into dedicated
 function

With the addition of hash-based integrity checking, the configuration
matrix is easier to represent in a dedicated function and with explicit
usage of IS_ENABLED().

Drop the now unnecessary stub for module_sig_check().

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 kernel/module/internal.h |  7 -------
 kernel/module/main.c     | 18 ++++++++++++++----
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 626cf8668a7eb9202fce13d631f39429a4fe0ace..42fbc53c6af66a1b531fcad08997742d838eb481 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -325,14 +325,7 @@ int module_enable_text_rox(const struct module *mod);
 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 				char *secstrings, struct module *mod);

-#ifdef CONFIG_MODULE_SIG
 int module_sig_check(struct load_info *info, int flags);
-#else /* !CONFIG_MODULE_SIG */
-static inline int module_sig_check(struct load_info *info, int flags)
-{
-	return 0;
-}
-#endif /* !CONFIG_MODULE_SIG */

 #ifdef CONFIG_DEBUG_KMEMLEAK
 void kmemleak_load_module(const struct module *mod, const struct load_info *info);
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 83c66205556fdde92152c131f1f58229c4f7f734..0c88d443a3bc894b18a7aa230cadf396e585c415 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -3247,6 +3247,16 @@ static int early_mod_check(struct load_info *info, int flags)
 	return err;
 }

+static int module_integrity_check(struct load_info *info, int flags)
+{
+	int err = 0;
+
+	if (IS_ENABLED(CONFIG_MODULE_SIG))
+		err = module_sig_check(info, flags);
+
+	return err;
+}
+
 /*
  * Allocate and load the module: note that size of section 0 is always
  * zero, and we rely on this for optional sections.
@@ -3260,18 +3270,18 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	char *after_dashes;

 	/*
-	 * Do the signature check (if any) first. All that
-	 * the signature check needs is info->len, it does
+	 * Do the integrity checks (if any) first. All that
+	 * they need is info->len, it does
 	 * not need any of the section info. That can be
 	 * set up later. This will minimize the chances
 	 * of a corrupt module causing problems before
-	 * we even get to the signature check.
+	 * we even get to the integrity check.
 	 *
 	 * The check will also adjust info->len by stripping
 	 * off the sig length at the end of the module, making
 	 * checks against info->len more correct.
 	 */
-	err = module_sig_check(info, flags);
+	err = module_integrity_check(info, flags);
 	if (err)
 		goto free_copy;

-- 
2.49.0