Re: [PATCH v3] add group restriction bitmap

Oleg Nesterov
2024-10-01T11:15:52Z

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.