[PATCH] module: expose load_info to arch module loader code

From: Jessica Yu
Date: Mon Apr 06 2020 - 12:04:44 EST


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@xxxxxxxxxx>
---

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@xxxxxxxxxxxxx

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@xxxxxxxxxx)
*/

-#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