Re: [PATCH v9 2/8] powerpc/ima: add support to initialize ima policy rules

[Lakshmi Ramasubramanian <nramas@linux.microsoft.com>]

On 10/25/2019 10:02 AM, Nayna Jain wrote:

 >> Is there any way to not use conditional compilation in
 >> the above array definition? Maybe define different functions to get
 >> "secure_rules" for when CONFIG_MODULE_SIG_FORCE is defined and when
 >> it is not defined.
 >
 > How will you decide which function to be called ?

Define the array in the C file:

const char *const secure_rules_kernel_check[] = {
    "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig",
    NULL
};

const char *const secure_rules_kernel_module_check[] = {
    "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig",
    "appraise func=MODULE_CHECK appraise_type=imasig|modsig",
    NULL
};

And, in the header file :

extern const char *const secure_rules_kernel_check;
extern const char *const secure_rules_kernel_module_check;

#ifdef CONFIG_MODULE_SIG_FORCE
const char *secure_rules() { return secure_rules_kernel_check; }
#else
const char *secure_rules() { return secure_rules_kernel_module_check;}
#endif // #ifdef CONFIG_MODULE_SIG_FORCE

If you want to avoid duplication, secure_rules_kernel_check and 
secure_rules_kernel_module_check could be defined in separate C files 
and conditionally compiled (in Makefile).


I was just trying to suggest the guidelines given in
"Section 21) Conditional Compilation" in coding-style.rst.

It says:
Whenever possible don't use preprocessor conditionals (#ifdef, #if) in 
.c files;...

Feel free to do what you think is appropriate.

thanks,
  -lakshmi