[PATCH v10 05/27] ima: Define ima_namespace struct and start moving variables into it

[Mimi Zohar]

On Tue, 2022-02-01 at 15:37 -0500, Stefan Berger wrote:
> Define the ima_namespace structure and the ima_namespace variable
> init_ima_ns for the host's IMA namespace. Implement basic functions for
> namespacing support.

Implement the basic functions - ima_ns_init()  and ima_init_namespace()
- for namespacing support.

> 
> Move variables related to the IMA policy into the ima_namespace. This way
> the IMA policy of an IMA namespace can be set and displayed using a
> front-end like securityfs.

> Implement ima_ns_from_file() to get the IMA namespace via the user
> namespace of the securityfs superblock that a file belongs to.

Currently, ima_ns_from_file() doesn't exist in this patch.

> 
> To get the current ima_namespace use &init_ima_ns when a function
> that is related to a policy rule is called.

In preparation for IMA namespacing, update the existing functions to
pass the ima_namespace struct.  For now, ...

> 
> 
> Signed-off-by: Stefan Berger <stefanb at linux.ibm.com>
> Acked-by: Christian Brauner <brauner at kernel.org>

After addressing the one inline comment,
	Reviewed-by: Mimi Zohar <zohar at linux.ibm.com>
> 
> ---

>  
> @@ -119,6 +117,17 @@ struct ima_kexec_hdr {
>  	u64 count;
>  };
>  
> +struct ima_namespace {
> +	/* policy rules */
> +	struct list_head ima_default_rules;
> +	struct list_head ima_policy_rules;
> +	struct list_head ima_temp_rules;

These local policy variables weren't previously commented, but with the
move to a structure it would be good to add comments.  For example, the
architecture policy rules persist even after a custom policy is loaded.

ima_default_rules: /* Kconfig, builtin, & arch rules */
ima_policy_rules:  /* arch & custom rules */

> +
> +	struct list_head __rcu *ima_rules;	/* current policy */

/* Pointer to the current policy */.

> +	int ima_policy_flag;
> +} __randomize_layout;
> +extern struct ima_namespace init_ima_ns;
> +
>  extern const int read_idmap[];
>  
>  #ifdef CONFIG_HAVE_IMA_KEXEC
> 
>  {
> +	struct ima_namespace *ns = &init_ima_ns;
>  	char *data;
>  	ssize_t result;
>