linux-kernel - Re: [RFC v6 08/40] richacl: Compute maximum file masks from an acl

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Date:	Wed, 2 Sep 2015 22:38:34 +0200
From:	Andreas Gruenbacher <agruenba@...hat.com>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	Andreas Gruenbacher <andreas.gruenbacher@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-nfs@...r.kernel.org, linux-api@...r.kernel.org,
	linux-cifs@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [RFC v6 08/40] richacl: Compute maximum file masks from an acl

2015-09-02 21:54 GMT+02:00 J. Bruce Fields <bfields@...ldses.org>:
>> +     richacl_for_each_entry_reverse(ace, acl) {
>> +             if (richace_is_inherit_only(ace))
>> +                     continue;
>> +
>> +             if (richace_is_owner(ace) ||
>> +                 (richace_is_unix_user(ace) &&
>> +                  uid_eq(ace->e_id.uid, owner))) {
>> +                     if (richace_is_allow(ace))
>> +                             acl->a_owner_mask |= ace->e_mask;
>> +                     else if (richace_is_deny(ace))
>> +                             acl->a_owner_mask &= ~ace->e_mask;
>> +             } else if (richace_is_everyone(ace)) {
>> +                     if (richace_is_allow(ace)) {
>> +                             acl->a_owner_mask |= ace->e_mask;
>> +                             acl->a_group_mask |= ace->e_mask & gmask;
>> +                             acl->a_other_mask |= ace->e_mask;
>> +                     } else if (richace_is_deny(ace)) {
>> +                             acl->a_owner_mask &= ~ace->e_mask;
>> +                             acl->a_group_mask &= ~ace->e_mask;
>> +                             acl->a_other_mask &= ~ace->e_mask;
>> +                     }
>> +             } else {
>> +                     if (richace_is_allow(ace)) {
>> +                             acl->a_owner_mask |= ace->e_mask & gmask;
>> +                             acl->a_group_mask |= ace->e_mask & gmask;
>
> I think we do that because we don't (we can't) know whether the owner
> might match this ace, so we assume that it will match, as that's what
> gives us the maximum.

Yes.

> But on first glance this is a little counterintuitive and maybe worth a
> comment.

I agree.

Thanks,
Andreas
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