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[PATCH v4 12/17] module: Move signature splitting up

Thomas Weißschuh posted 17 patches 3 weeks, 3 days ago
[PATCH v4 12/17] module: Move signature splitting up
Posted by Thomas Weißschuh 3 weeks, 3 days ago 
The signature splitting will also be used by CONFIG_MODULE_HASHES.

Move it up the callchain, so the result can be reused.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 kernel/module/internal.h |  2 +-
 kernel/module/main.c     | 13 ++++++++++++-
 kernel/module/signing.c  | 21 +++++++--------------
 3 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index e053c29a5d08..e2d49122c2a1 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -337,7 +337,7 @@ int module_enforce_rwx_sections(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
 void module_mark_ro_after_init(const Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 			       const char *secstrings);
 
-int module_sig_check(struct load_info *info, int flags);
+int module_sig_check(struct load_info *info, const u8 *sig, size_t sig_len);
 
 #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 c09b25c0166a..d65bc300a78c 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -3346,10 +3346,21 @@ static int early_mod_check(struct load_info *info, int flags)
 
 static int module_integrity_check(struct load_info *info, int flags)
 {
+	bool mangled_module = flags & (MODULE_INIT_IGNORE_MODVERSIONS |
+				       MODULE_INIT_IGNORE_VERMAGIC);
+	size_t sig_len;
+	const u8 *sig;
 	int err = 0;
 
+	if (IS_ENABLED(CONFIG_MODULE_SIG_POLICY)) {
+		err = mod_split_sig(info->hdr, &info->len, mangled_module,
+				    &sig_len, &sig, "module");
+		if (err)
+			return err;
+	}
+
 	if (IS_ENABLED(CONFIG_MODULE_SIG))
-		err = module_sig_check(info, flags);
+		err = module_sig_check(info, sig, sig_len);
 
 	if (err)
 		return err;
diff --git a/kernel/module/signing.c b/kernel/module/signing.c
index 8a5f66389116..86164761cac7 100644
--- a/kernel/module/signing.c
+++ b/kernel/module/signing.c
@@ -15,26 +15,19 @@
 #include <uapi/linux/module.h>
 #include "internal.h"
 
-int module_sig_check(struct load_info *info, int flags)
+int module_sig_check(struct load_info *info, const u8 *sig, size_t sig_len)
 {
 	int err;
 	const char *reason;
 	const void *mod = info->hdr;
-	size_t sig_len;
-	const u8 *sig;
-	bool mangled_module = flags & (MODULE_INIT_IGNORE_MODVERSIONS |
-				       MODULE_INIT_IGNORE_VERMAGIC);
 
-	err = mod_split_sig(info->hdr, &info->len, mangled_module, &sig_len, &sig, "module");
+	err = verify_pkcs7_signature(mod, info->len, sig, sig_len,
+				     VERIFY_USE_SECONDARY_KEYRING,
+				     VERIFYING_MODULE_SIGNATURE,
+				     NULL, NULL);
 	if (!err) {
-		err = verify_pkcs7_signature(mod, info->len, sig, sig_len,
-					     VERIFY_USE_SECONDARY_KEYRING,
-					     VERIFYING_MODULE_SIGNATURE,
-					     NULL, NULL);
-		if (!err) {
-			info->sig_ok = true;
-			return 0;
-		}
+		info->sig_ok = true;
+		return 0;
 	}
 
 	/*

-- 
2.52.0
Re: [PATCH v4 12/17] module: Move signature splitting up
Posted by Petr Pavlu 1 week, 1 day ago 
On 1/13/26 1:28 PM, Thomas Weißschuh wrote:
> The signature splitting will also be used by CONFIG_MODULE_HASHES.
> 
> Move it up the callchain, so the result can be reused.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> [...]
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index c09b25c0166a..d65bc300a78c 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -3346,10 +3346,21 @@ static int early_mod_check(struct load_info *info, int flags)
>  
>  static int module_integrity_check(struct load_info *info, int flags)
>  {
> +	bool mangled_module = flags & (MODULE_INIT_IGNORE_MODVERSIONS |
> +				       MODULE_INIT_IGNORE_VERMAGIC);
> +	size_t sig_len;
> +	const u8 *sig;
>  	int err = 0;
>  
> +	if (IS_ENABLED(CONFIG_MODULE_SIG_POLICY)) {
> +		err = mod_split_sig(info->hdr, &info->len, mangled_module,
> +				    &sig_len, &sig, "module");
> +		if (err)
> +			return err;
> +	}
> +
>  	if (IS_ENABLED(CONFIG_MODULE_SIG))
> -		err = module_sig_check(info, flags);
> +		err = module_sig_check(info, sig, sig_len);
>  
>  	if (err)
>  		return err;

I suggest moving the IS_ENABLED(CONFIG_MODULE_SIG) block under the
new IS_ENABLED(CONFIG_MODULE_SIG_POLICY) section. I realize that
CONFIG_MODULE_SIG implies CONFIG_MODULE_SIG_POLICY, but I believe this
change makes it more apparent that this it the case. Otherwise, one
might for example wonder if sig_len in the module_sig_check() call can
be undefined.

	if (IS_ENABLED(CONFIG_MODULE_SIG_POLICY)) {
		err = mod_split_sig(info->hdr, &info->len, mangled_module,
				    &sig_len, &sig, "module");
		if (err)
			return err;

		if (IS_ENABLED(CONFIG_MODULE_SIG))
			err = module_sig_check(info, sig, sig_len);
	}

-- 
Thanks,
Petr
Re: [PATCH v4 12/17] module: Move signature splitting up
Posted by Thomas Weißschuh 3 days, 17 hours ago 
On 2026-01-29 15:41:43+0100, Petr Pavlu wrote:
> On 1/13/26 1:28 PM, Thomas Weißschuh wrote:
> > The signature splitting will also be used by CONFIG_MODULE_HASHES.
> > 
> > Move it up the callchain, so the result can be reused.
> > 
> > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> > ---
> > [...]
> > diff --git a/kernel/module/main.c b/kernel/module/main.c
> > index c09b25c0166a..d65bc300a78c 100644
> > --- a/kernel/module/main.c
> > +++ b/kernel/module/main.c
> > @@ -3346,10 +3346,21 @@ static int early_mod_check(struct load_info *info, int flags)
> >  
> >  static int module_integrity_check(struct load_info *info, int flags)
> >  {
> > +	bool mangled_module = flags & (MODULE_INIT_IGNORE_MODVERSIONS |
> > +				       MODULE_INIT_IGNORE_VERMAGIC);
> > +	size_t sig_len;
> > +	const u8 *sig;
> >  	int err = 0;
> >  
> > +	if (IS_ENABLED(CONFIG_MODULE_SIG_POLICY)) {
> > +		err = mod_split_sig(info->hdr, &info->len, mangled_module,
> > +				    &sig_len, &sig, "module");
> > +		if (err)
> > +			return err;
> > +	}
> > +
> >  	if (IS_ENABLED(CONFIG_MODULE_SIG))
> > -		err = module_sig_check(info, flags);
> > +		err = module_sig_check(info, sig, sig_len);
> >  
> >  	if (err)
> >  		return err;
> 
> I suggest moving the IS_ENABLED(CONFIG_MODULE_SIG) block under the
> new IS_ENABLED(CONFIG_MODULE_SIG_POLICY) section. I realize that
> CONFIG_MODULE_SIG implies CONFIG_MODULE_SIG_POLICY, but I believe this
> change makes it more apparent that this it the case. Otherwise, one
> might for example wonder if sig_len in the module_sig_check() call can
> be undefined.
> 
> 	if (IS_ENABLED(CONFIG_MODULE_SIG_POLICY)) {
> 		err = mod_split_sig(info->hdr, &info->len, mangled_module,
> 				    &sig_len, &sig, "module");
> 		if (err)
> 			return err;
> 
> 		if (IS_ENABLED(CONFIG_MODULE_SIG))
> 			err = module_sig_check(info, sig, sig_len);
> 	}

Ack.

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