On December 21, 2023 4:16:56 AM PST, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
>Cc +Kees
>
>Christophe Leroy <christophe.leroy@xxxxxxxxxx> writes:
>> Declaring rodata_enabled and mark_rodata_ro() at all time
>> helps removing related #ifdefery in C files.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
>> ---
>> include/linux/init.h | 4 ----
>> init/main.c | 21 +++++++--------------
>> 2 files changed, 7 insertions(+), 18 deletions(-)
>>
>> diff --git a/include/linux/init.h b/include/linux/init.h
>> index 01b52c9c7526..d2b47be38a07 100644
>> --- a/include/linux/init.h
>> +++ b/include/linux/init.h
>> @@ -168,12 +168,8 @@ extern initcall_entry_t __initcall_end[];
>>
>> extern struct file_system_type rootfs_fs_type;
>>
>> -#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
>> extern bool rodata_enabled;
>> -#endif
>> -#ifdef CONFIG_STRICT_KERNEL_RWX
>> void mark_rodata_ro(void);
>> -#endif
>>
>> extern void (*late_time_init)(void);
>>
>> diff --git a/init/main.c b/init/main.c
>> index e24b0780fdff..807df08c501f 100644
>> --- a/init/main.c
>> +++ b/init/main.c
>> @@ -1396,10 +1396,9 @@ static int __init set_debug_rodata(char *str)
>> early_param("rodata", set_debug_rodata);
>> #endif
>>
>> -#ifdef CONFIG_STRICT_KERNEL_RWX
>> static void mark_readonly(void)
>> {
>> - if (rodata_enabled) {
>> + if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) && rodata_enabled) {
I think this will break without rodata_enabled actual existing on other architectures. (Only declaration was made visible, not the definition, which is above here and still behind ifdefs?)
-Kees
>> /*
>> * load_module() results in W+X mappings, which are cleaned
>> * up with call_rcu(). Let's make sure that queued work is
>> @@ -1409,20 +1408,14 @@ static void mark_readonly(void)
>> rcu_barrier();
>> mark_rodata_ro();
>> rodata_test();
>> - } else
>> + } else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) {
>> pr_info("Kernel memory protection disabled.\n");
>> + } else if (IS_ENABLED(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)) {
>> + pr_warn("Kernel memory protection not selected by kernel config.\n");
>> + } else {
>> + pr_warn("This architecture does not have kernel memory protection.\n");
>> + }
>> }
>> -#elif defined(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)
>> -static inline void mark_readonly(void)
>> -{
>> - pr_warn("Kernel memory protection not selected by kernel config.\n");
>> -}
>> -#else
>> -static inline void mark_readonly(void)
>> -{
>> - pr_warn("This architecture does not have kernel memory protection.\n");
>> -}
>> -#endif
>>
>> void __weak free_initmem(void)
>> {
>> --
>> 2.41.0
--
Kees Cook
