From bdc877ba6b7ff1b6d2ebeff11e63da4a50a54854 Mon Sep 17 00:00:00 2001 From: Petr Pavlu Date: Mon, 30 Jun 2025 16:32:34 +0200 Subject: module: Restore the moduleparam prefix length check The moduleparam code allows modules to provide their own definition of MODULE_PARAM_PREFIX, instead of using the default KBUILD_MODNAME ".". Commit 730b69d22525 ("module: check kernel param length at compile time, not runtime") added a check to ensure the prefix doesn't exceed MODULE_NAME_LEN, as this is what param_sysfs_builtin() expects. Later, commit 58f86cc89c33 ("VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms.") removed this check, but there is no indication this was intentional. Since the check is still useful for param_sysfs_builtin() to function properly, reintroduce it in __module_param_call(), but in a modernized form using static_assert(). While here, clean up the __module_param_call() comments. In particular, remove the comment "Default value instead of permissions?", which comes from commit 9774a1f54f17 ("[PATCH] Compile-time check re world-writeable module params"). This comment was related to the test variable __param_perm_check_##name, which was removed in the previously mentioned commit 58f86cc89c33. Fixes: 58f86cc89c33 ("VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms.") Signed-off-by: Petr Pavlu Reviewed-by: Daniel Gomez Link: https://lore.kernel.org/r/20250630143535.267745-4-petr.pavlu@suse.com Signed-off-by: Daniel Gomez --- include/linux/moduleparam.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'include/linux/moduleparam.h') diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index bfb85fd13e1f..110e9d09de24 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -282,10 +282,9 @@ struct kparam_array #define __moduleparam_const const #endif -/* This is the fundamental function for registering boot/module - parameters. */ +/* This is the fundamental function for registering boot/module parameters. */ #define __module_param_call(prefix, name, ops, arg, perm, level, flags) \ - /* Default value instead of permissions? */ \ + static_assert(sizeof(""prefix) - 1 <= MAX_PARAM_PREFIX_LEN); \ static const char __param_str_##name[] = prefix #name; \ static struct kernel_param __moduleparam_const __param_##name \ __used __section("__param") \ -- cgit v1.2.3 From 40a826bd6c82ae45cfd3a19cd2a60a10f56b74c0 Mon Sep 17 00:00:00 2001 From: Petr Pavlu Date: Mon, 30 Jun 2025 16:32:36 +0200 Subject: module: Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME_LEN The maximum module name length (MODULE_NAME_LEN) is somewhat confusingly defined in terms of the maximum parameter prefix length (MAX_PARAM_PREFIX_LEN), when in fact the dependency is in the opposite direction. This split originates from commit 730b69d22525 ("module: check kernel param length at compile time, not runtime"). The code needed to use MODULE_NAME_LEN in moduleparam.h, but because module.h requires moduleparam.h, this created a circular dependency. It was resolved by introducing MAX_PARAM_PREFIX_LEN in moduleparam.h and defining MODULE_NAME_LEN in module.h in terms of MAX_PARAM_PREFIX_LEN. Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME_LEN for clarity. This matches the similar approach of defining MODULE_INFO in module.h and __MODULE_INFO in moduleparam.h. Signed-off-by: Petr Pavlu Reviewed-by: Daniel Gomez Link: https://lore.kernel.org/r/20250630143535.267745-6-petr.pavlu@suse.com Signed-off-by: Daniel Gomez --- include/linux/module.h | 2 +- include/linux/moduleparam.h | 12 ++++++++---- 2 files changed, 9 insertions(+), 5 deletions(-) (limited to 'include/linux/moduleparam.h') diff --git a/include/linux/module.h b/include/linux/module.h index 5fe812de2d84..313ecb8e5181 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -33,7 +33,7 @@ #include #include -#define MODULE_NAME_LEN MAX_PARAM_PREFIX_LEN +#define MODULE_NAME_LEN __MODULE_NAME_LEN struct modversion_info { unsigned long crc; diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 110e9d09de24..a04a2bc4f51e 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -6,6 +6,13 @@ #include #include +/* + * The maximum module name length, including the NUL byte. + * Chosen so that structs with an unsigned long line up, specifically + * modversion_info. + */ +#define __MODULE_NAME_LEN (64 - sizeof(unsigned long)) + /* You can override this manually, but generally this should match the module name. */ #ifdef MODULE @@ -17,9 +24,6 @@ #define __MODULE_INFO_PREFIX KBUILD_MODNAME "." #endif -/* Chosen so that structs with an unsigned long line up. */ -#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long)) - #define __MODULE_INFO(tag, name, info) \ static const char __UNIQUE_ID(name)[] \ __used __section(".modinfo") __aligned(1) \ @@ -284,7 +288,7 @@ struct kparam_array /* This is the fundamental function for registering boot/module parameters. */ #define __module_param_call(prefix, name, ops, arg, perm, level, flags) \ - static_assert(sizeof(""prefix) - 1 <= MAX_PARAM_PREFIX_LEN); \ + static_assert(sizeof(""prefix) - 1 <= __MODULE_NAME_LEN); \ static const char __param_str_##name[] = prefix #name; \ static struct kernel_param __moduleparam_const __param_##name \ __used __section("__param") \ -- cgit v1.2.3