On Sat, Sep 12, 2015 at 12:12:16AM +0200, Andreas Grünbacher wrote: > 2015-09-11 23:16 GMT+02:00 J. Bruce Fields <bfields@xxxxxxxxxxxx>: > > On Sat, Sep 05, 2015 at 12:27:05PM +0200, Andreas Gruenbacher wrote: > >> + /* > >> + * Apply the group file mask to entries other than owner@ and > >> + * everyone@ or user entries matching the owner. This ensures > >> + * that we grant the same permissions as the acl computed by > >> + * richacl_apply_masks(). > >> + * > >> + * Without this restriction, the following richacl would grant > >> + * rw access to processes which are both the owner and in the > >> + * owning group, but not to other users in the owning group, > >> + * which could not be represented without masks: > >> + * > >> + * owner:rw::mask > >> + * group@:rw::allow > >> + */ > >> + if ((acl->a_flags & RICHACL_MASKED) && richace_is_allow(ace)) > >> + ace_mask &= acl->a_group_mask; > > > > I'm having trouble understanding this. I think the problem is that I > > don't really understand the notation in your example. Is a_group_mask > > zero in that example? I think it must be, in which case, OK I think I > > get it. > > Yes. I'm not sure if the example becomes easier to understand when the > empty group mask and perhaps also the other mask is included. I think it would have been for me. In general I find it confusing to present the mask bits as additional ACEs--they're really pretty different. > > (Though I still have to think about it a little more to convince myself > > that richacl_apply_masks() always gets the same result.) > > I have tried to break the algorithm into digestible pieces. Do you see > another way to make things easier to understand? I just haven't reread those carefully enough yet, working on it.... --b. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
