[PATCH v2] module: Allow to disable modsign in kernel cmdline

[PATCH v2] module: Allow to disable modsign in kernel cmdline

[Tianjia Zhang]

This option 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>
---
 Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
 kernel/module.c                                 | 8 ++++++++
 2 files changed, 14 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7bc83f3d9bdf..00ed7566959f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3190,6 +3190,12 @@
 	noirqdebug	[X86-32] Disables the code which attempts to detect and
 			disable unhandled interrupt sources.
 
+	no_modsig_enforce
+			[KNL] When CONFIG_MODULE_SIG_FORCE is set, this option
+			allows to disable modsign completely at the beginning.
+			This means that modules without (valid) signatures will
+			success to load.
+
 	no_timer_check	[X86,APIC] Disables the code which tests for
 			broken timer IRQ sources.
 
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 v2] module: Allow to disable modsign in kernel cmdline

[Randy Dunlap]

Hi,

On 4/27/20 10:05 PM, Tianjia Zhang wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 7bc83f3d9bdf..00ed7566959f 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3190,6 +3190,12 @@
>  	noirqdebug	[X86-32] Disables the code which attempts to detect and
>  			disable unhandled interrupt sources.
>  
> +	no_modsig_enforce
> +			[KNL] When CONFIG_MODULE_SIG_FORCE is set, this option
> +			allows to disable modsign completely at the beginning.
> +			This means that modules without (valid) signatures will
> +			success to load.

			succeed to load.

			succeed in loading.

			load successfully.
I prefer this one.....  ^^^^^^^^^^^^^^^^^^^^^

			be loaded successfully.


> +
>  	no_timer_check	[X86,APIC] Disables the code which tests for
>  			broken timer IRQ sources.
>  

thanks.
-- 
~Randy

Re: [PATCH v2] module: Allow to disable modsign in kernel cmdline

[Tianjia Zhang]

On 2020/4/28 13:52, Randy Dunlap wrote:
> Hi,
> 
> On 4/27/20 10:05 PM, Tianjia Zhang wrote:
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index 7bc83f3d9bdf..00ed7566959f 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -3190,6 +3190,12 @@
>>   	noirqdebug	[X86-32] Disables the code which attempts to detect and
>>   			disable unhandled interrupt sources.
>>   
>> +	no_modsig_enforce
>> +			[KNL] When CONFIG_MODULE_SIG_FORCE is set, this option
>> +			allows to disable modsign completely at the beginning.
>> +			This means that modules without (valid) signatures will
>> +			success to load.
> 
> 			succeed to load.
> 
> 			succeed in loading.
> 
> 			load successfully.
> I prefer this one.....  ^^^^^^^^^^^^^^^^^^^^^
> 
> 			be loaded successfully.
> 
> 
>> +
>>   	no_timer_check	[X86,APIC] Disables the code which tests for
>>   			broken timer IRQ sources.
>>   
> 
> thanks.
> 

v3 patch has been submitted, thank you for your suggestion.

Thanks,
Tianjia