[PATCH 2/5] audit: complex interfield comparison helper

[Eric Paris]

On Wed, 2012-01-04 at 15:47 -0500, Eric Paris wrote:
> Rather than code the same loop over and over implement a helper function which
> uses some pointer magic to make it generic enough to be used numerous places
> as we implement more audit interfield comparisons
> 
> Signed-off-by: Eric Paris <eparis at redhat.com>
> ---

The change from the last version is simply to take a uid_t and a pointer
to a struct audit_name instead of taking two pointers.  This allows us
to get the first uid from either a cred or the task struct.

>  kernel/auditsc.c |   50 +++++++++++++++++++++++++++++++++++++++-----------
>  1 files changed, 39 insertions(+), 11 deletions(-)
> 
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index efb1763..45c13c5 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -463,25 +463,53 @@ static int match_tree_refs(struct audit_context *ctx, struct audit_tree *tree)
>  	return 0;
>  }
>  
> +static int audit_compare_id(uid_t uid1,
> +			    struct audit_names *name,
> +			    unsigned long name_offset,
> +			    struct audit_field *f,
> +			    struct audit_context *ctx)
> +{
> +	struct audit_names *n;
> +	unsigned long addr;
> +	uid_t uid2;
> +	int rc;
> +
> +	if (name) {
> +		addr = (unsigned long)name;
> +		addr += name_offset;
> +
> +		uid2 = *(uid_t *)addr;
> +		rc = audit_comparator(uid1, f->op, uid2);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	if (ctx) {
> +		list_for_each_entry(n, &ctx->names_list, list) {
> +			addr = (unsigned long)n;
> +			addr += name_offset;
> +
> +			uid2 = *(uid_t *)addr;
> +
> +			rc = audit_comparator(uid1, f->op, uid2);
> +			if (rc)
> +				return rc;
> +		}
> +	}
> +	return 0;
> +}
> +
>  static int audit_field_compare(struct task_struct *tsk,
>  			       const struct cred *cred,
>  			       struct audit_field *f,
>  			       struct audit_context *ctx,
>  			       struct audit_names *name)
>  {
> -	struct audit_names *n;
> -
>  	switch (f->val) {
>  	case AUDIT_COMPARE_UID_TO_OBJ_UID:
> -		if (name) {
> -			return audit_comparator(cred->uid, f->op, name->uid);
> -		} else if (ctx) {
> -			list_for_each_entry(n, &ctx->names_list, list) {
> -				if (audit_comparator(cred->uid, f->op, n->uid))
> -					return 1;
> -			}
> -		}
> -		break;
> +		return audit_compare_id(cred->uid,
> +					name, offsetof(struct audit_names, uid),
> +					f, ctx);
>  	default:
>  		WARN(1, "Missing AUDIT_COMPARE define.  Report as a bug\n");
>  		return 0;