Re: [ LIBSEMANAGE ] Runtime control over preservebools argument

[Joshua Brindle <jbrindle@tresys.com>]

Ivan Gyurdiev wrote:
> Stephen Smalley wrote:
> 
>> On Fri, 2005-11-04 at 09:22 -0500, Ivan Gyurdiev wrote:
>>  
>>
>>> So, how do I specify that this is not a transient change, and I want 
>>> my booleans loaded into policy immediately?
>>>     
>>
>>
>> Ah, I see - setsebool -P wants to both update the saved settings and
>> load the result rather than preserving current settings.  So it wants
>> libsemanage to call load_policy with -b, unlike semodule.  Options are:
>> - add a semanage interface to set a property on the handle to control
>> whether booleans are preserved or not (by altering the args to
>> load_policy for that handle), similar to the existing interface for
>> controlling whether reloads are performed, or
>>   
> 
> Editing an argument string for programs in C is... probably one of the 
> most uncool patches I've ever written.
> I guess the end justifies the means...
> 
> Should pass valgrind, and work when called repeatedly with values 0 or 
> 1. Maybe the reload=0 case is a bit wrong - argument string cannot 
> contain "-b" anywhere.
> 
> I also fixed the memory leak in setsebool - see other patch (which 
> should be applied first).
> 
> Now booleans update correctly (minus migration issues - see other mail).
> Next: make them update in less than 10 seconds :)
> 
> 
<snip>

> +	if (do_reload) {
> +		char* prev_args = conf->load_policy->args;
> +		int len = (prev_args == NULL)? 0: strlen(prev_args);
> +		char* ptr = (char*) realloc(prev_args, len + 4);
> +
> +		if (!ptr) {
> +			ERR(sh, "out of memory, could not configure "
> +				"boolean reload");
> +			return STATUS_ERR;
> +		}
> +		strcpy(ptr + len, " -b");
> +		conf->load_policy->args = ptr;
> +
> +	} else {
> +		char* ptr = conf->load_policy->args;
> +
> +		while(*ptr++) {
> +			if (!strcmp(ptr, "-b")) {
> +				*ptr++ = ' ';	
> +				*ptr++ = ' ';
> +			}
> +		}
> +	}
> +	return STATUS_SUCCESS;
> +}
> +
I think you are doing this in the wrong place. Rather than mangling the 
argument string every time this function is called you should just add 
something to the handle that indicates whether or not to preserve 
booleans, and do this at load time.

However, I don't know if this is the right approach anyway. If someone 
sets a boolean without -P , foo, and then sets another boolean with -P 
you will revert foo when loading the new policy.

IMHO while we will need to regenerate the policy we should not load it 
and instead just set the runtime state. This will work for the common 
case but there is something of a corner case where the above scenerio 
happens and a module is also inserted in the same transaction, not sure 
how to handle that one.

Joshua

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