Re: [PATCH v3] add group restriction bitmap

[Oleg Nesterov]

I can't comment the intent, just some nits about implementation.

On 09/30, Stas Sergeev wrote:
>
>  struct group_info {
>  	refcount_t	usage;
> +	unsigned int	restrict_bitmap;

Why not unsigned long?

>  int groups_search(const struct group_info *group_info, kgid_t grp)
>  {
>  	unsigned int left, right;
> @@ -105,7 +108,7 @@ int groups_search(const struct group_info *group_info, kgid_t grp)
>  		else if (gid_lt(grp, group_info->gid[mid]))
>  			right = mid;
>  		else
> -			return 1;
> +			return mid + 1;

Suppose we change groups_search()

	--- a/kernel/groups.c
	+++ b/kernel/groups.c
	@@ -104,8 +104,11 @@ int groups_search(const struct group_info *group_info, kgid_t grp)
				left = mid + 1;
			else if (gid_lt(grp, group_info->gid[mid]))
				right = mid;
	-		else
	-			return 1;
	+		else {
	+			bool r = mid < BITS_PER_LONG &&
	+				 test_bit(mid, &group_info->restrict_bitmap);
	+			return r ? -1 : 1;
	+		}
		}
		return 0;
	 }

so that it returns, say, -1 if the found grp is restricted.

Then everything else can be greatly simplified, afaics...

Oleg.