linux-kernel - [PATCH] module: expose load_info to arch module loader code

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Date:   Mon,  6 Apr 2020 18:04:20 +0200
From:   Jessica Yu <jeyu@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Jessica Yu <jeyu@...nel.org>
Subject: [PATCH] module: expose load_info to arch module loader code

The x86 module loader wants to check the value of a modinfo flag
(sld_safe), before proceeding to scan the module text for VMX
instructions. Unfortunately the arch module code currently does not have
access to load_info, but we can easily expose that via moduleloader.h,
which every arch module code must already include.

Signed-off-by: Jessica Yu <jeyu@...nel.org>
---

Does this help? You may also need to implement a new arch-specific hook
in check_modinfo() to check for sld_safe, and I guess we might need to
expose get_modinfo() too. I realize that the detect-VMX-modules patchset
[1] is still very much in-flight, so if you do end up needing this, feel
free to just add this patch to the patchset.

[1] http://lore.kernel.org/r/20200402123258.895628824@linutronix.de

 include/linux/moduleloader.h | 20 ++++++++++++++++++++
 kernel/module-internal.h     | 23 -----------------------
 kernel/module_signing.c      |  2 +-
 3 files changed, 21 insertions(+), 24 deletions(-)

diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index ca92aea8a6bd..2ca0bb783d1e 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h
@@ -6,6 +6,26 @@
 #include <linux/module.h>
 #include <linux/elf.h>
 
+struct load_info {
+	const char *name;
+	/* pointer to module in temporary copy, freed at end of load_module() */
+	struct module *mod;
+	Elf_Ehdr *hdr;
+	unsigned long len;
+	Elf_Shdr *sechdrs;
+	char *secstrings, *strtab;
+	unsigned long symoffs, stroffs, init_typeoffs, core_typeoffs;
+	struct _ddebug *debug;
+	unsigned int num_debug;
+	bool sig_ok;
+#ifdef CONFIG_KALLSYMS
+	unsigned long mod_kallsyms_init_off;
+#endif
+	struct {
+		unsigned int sym, str, mod, vers, info, pcpu;
+	} index;
+};
+
 /* These may be implemented by architectures that need to hook into the
  * module loader code.  Architectures that don't need to do anything special
  * can just rely on the 'weak' default hooks defined in kernel/module.c.
diff --git a/kernel/module-internal.h b/kernel/module-internal.h
index 33783abc377b..98a873691f1b 100644
--- a/kernel/module-internal.h
+++ b/kernel/module-internal.h
@@ -5,27 +5,4 @@
  * Written by David Howells (dhowells@...hat.com)
  */
 
-#include <linux/elf.h>
-#include <asm/module.h>
-
-struct load_info {
-	const char *name;
-	/* pointer to module in temporary copy, freed at end of load_module() */
-	struct module *mod;
-	Elf_Ehdr *hdr;
-	unsigned long len;
-	Elf_Shdr *sechdrs;
-	char *secstrings, *strtab;
-	unsigned long symoffs, stroffs, init_typeoffs, core_typeoffs;
-	struct _ddebug *debug;
-	unsigned int num_debug;
-	bool sig_ok;
-#ifdef CONFIG_KALLSYMS
-	unsigned long mod_kallsyms_init_off;
-#endif
-	struct {
-		unsigned int sym, str, mod, vers, info, pcpu;
-	} index;
-};
-
 extern int mod_verify_sig(const void *mod, struct load_info *info);
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index 9d9fc678c91d..2de41a3ab8a8 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -8,11 +8,11 @@
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/module.h>
+#include <linux/moduleloader.h>
 #include <linux/module_signature.h>
 #include <linux/string.h>
 #include <linux/verification.h>
 #include <crypto/public_key.h>
-#include "module-internal.h"
 
 /*
  * Verify the signature on a module.
-- 
2.16.4