Messages in this thread | | | Date | Tue, 3 Dec 2013 13:36:34 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/2] test: add minimal module for verification testing |
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On Tue, 3 Dec 2013 13:27:33 -0800 Kees Cook <keescook@chromium.org> wrote:
> When doing module loading verification tests (for example, with module > singing, or LSM hooks), it is very handy to have a module that can be > built on all systems under test, isn't auto-loaded at boot, and has > no device or similar dependencies. This creates the "test_module.ko" > module for that purpose, which only reports its load and unload to printk. > > --- /dev/null > +++ b/kernel/test_module.c > @@ -0,0 +1,26 @@ > +/* > + * "hello world" kernel module > + */ > + > +#define pr_fmt(fmt) "test_module: " fmt > + > +#include <linux/module.h>
It really should have a whole bunch more includes, rather than relying on winning the nested include lottery.
> +static int __init test_module_init(void) > +{ > + pr_info("Hello, world\n");
pr_info is maybe too low a facility level? Pretty much the whole point of the module is to print this message, so let's ensure that it is visible.
> + return 0; > +} > + > +module_init(test_module_init); > + > +static void __exit test_module_exit(void) > +{ > + pr_info("Goodbye\n"); > +} > + > +module_exit(test_module_exit); > + > +MODULE_AUTHOR("Kees Cook <keescook@chromium.org>"); > +MODULE_LICENSE("GPL"); > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index db25707aa41b..20abc92032e0 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1578,6 +1578,20 @@ config DMA_API_DEBUG > This option causes a performance degredation. Use only if you want > to debug device drivers. If unsure, say N. > > +config TEST_MODULE > + tristate "Test module loading with 'hello world' module" > + default n > + depends on m > + help > + This builds the "test_module" module that emits "Hello, world" > + on printk when loaded. It is designed to be used for basic > + evaluation of the module loading subsystem (for example when > + validating module verification). It lacks any extra dependencies, > + and will not normally be loaded by the system unless explicitly > + request by name.
Would be useful to have a comment along these lines in test_module.c, so readers know why it exists.
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