[PATCH] module: Allow to disable modsign in kernel cmdline

[PATCH] module: Allow to disable modsign in kernel cmdline

[Tianjia Zhang]

This change allows to disable modsign completely at the beginning,
and turn off by set the kernel cmdline `no_modsig_enforce` when
CONFIG_MODULE_SIG_FORCE is enabled.

Yet another change allows to always show the current status of
modsign through `/sys/module/module/parameters/sig_enforce`.

Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
---
 kernel/module.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index 646f1e2330d2..0e68e1286377 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -269,6 +269,14 @@ static void module_assert_mutex_or_preempt(void)
 
 static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
 module_param(sig_enforce, bool_enable_only, 0644);
+#ifdef CONFIG_MODULE_SIG_FORCE
+static int __init set_no_modsig_enforce(char *str)
+{
+	sig_enforce = false;
+	return 1;
+}
+__setup("no_modsig_enforce", set_no_modsig_enforce);
+#endif /* !CONFIG_MODULE_SIG_FORCE */
 
 /*
  * Export sig_enforce kernel cmdline parameter to allow other subsystems rely
-- 
2.17.1

Re: [PATCH] module: Allow to disable modsign in kernel cmdline

[Randy Dunlap]

On 4/27/20 8:43 PM, Tianjia Zhang wrote:
> This change allows to disable modsign completely at the beginning,
> and turn off by set the kernel cmdline `no_modsig_enforce` when
> CONFIG_MODULE_SIG_FORCE is enabled.
> 
> Yet another change allows to always show the current status of
> modsign through `/sys/module/module/parameters/sig_enforce`.
> 
> Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> ---
>  kernel/module.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/kernel/module.c b/kernel/module.c
> index 646f1e2330d2..0e68e1286377 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -269,6 +269,14 @@ static void module_assert_mutex_or_preempt(void)
>  
>  static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
>  module_param(sig_enforce, bool_enable_only, 0644);
> +#ifdef CONFIG_MODULE_SIG_FORCE
> +static int __init set_no_modsig_enforce(char *str)
> +{
> +	sig_enforce = false;
> +	return 1;
> +}
> +__setup("no_modsig_enforce", set_no_modsig_enforce);
> +#endif /* !CONFIG_MODULE_SIG_FORCE */
>  
>  /*
>   * Export sig_enforce kernel cmdline parameter to allow other subsystems rely
> 

Hi,
Please document this cmdline option, probably in
Documentation/admin-guide/kernel-parameters.txt.

thanks.

-- 
~Randy

Re: [PATCH] module: Allow to disable modsign in kernel cmdline

[Tianjia Zhang]

On 2020/4/28 11:47, Randy Dunlap wrote:
> On 4/27/20 8:43 PM, Tianjia Zhang wrote:
>> This change allows to disable modsign completely at the beginning,
>> and turn off by set the kernel cmdline `no_modsig_enforce` when
>> CONFIG_MODULE_SIG_FORCE is enabled.
>>
>> Yet another change allows to always show the current status of
>> modsign through `/sys/module/module/parameters/sig_enforce`.
>>
>> Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>
>> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
>> ---
>>   kernel/module.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/kernel/module.c b/kernel/module.c
>> index 646f1e2330d2..0e68e1286377 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -269,6 +269,14 @@ static void module_assert_mutex_or_preempt(void)
>>   
>>   static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
>>   module_param(sig_enforce, bool_enable_only, 0644);
>> +#ifdef CONFIG_MODULE_SIG_FORCE
>> +static int __init set_no_modsig_enforce(char *str)
>> +{
>> +	sig_enforce = false;
>> +	return 1;
>> +}
>> +__setup("no_modsig_enforce", set_no_modsig_enforce);
>> +#endif /* !CONFIG_MODULE_SIG_FORCE */
>>   
>>   /*
>>    * Export sig_enforce kernel cmdline parameter to allow other subsystems rely
>>
> 
> Hi,
> Please document this cmdline option, probably in
> Documentation/admin-guide/kernel-parameters.txt.
> 
> thanks.
> 

Thanks for your information, I will submit a v2 patch.

Thanks and best,
Tianjia