On Thu, 2009-07-30 at 13:50 -0400, Eric Paris wrote: > On Thu, 2009-07-30 at 11:58 -0400, Stephen Smalley wrote: > > On Thu, 2009-07-30 at 10:54 -0500, Serge E. Hallyn wrote: > > > Quoting Eric Paris (eparis@xxxxxxxxxx): > > > > On Thu, 2009-07-30 at 00:14 -0500, Serge E. Hallyn wrote: > > > > > Quoting Eric Paris (eparis@xxxxxxxxxx): > > > > > > Currently we duplicate the mmap_min_addr test in cap_file_mmap and in > > > > > > security_file_mmap if !CONFIG_SECURITY. This patch moves cap_file_mmap > > > > > > into commoncap.c and then calls that function directly from > > > > > > security_file_mmap ifndef CONFIG_SECURITY like all of the other capability > > > > > > checks are done. > > > > > > > > > > It also > > > > > > > > > > 1. changes the return value in error case from -EACCES to > > > > > -EPERM > > > > > 2. no onger sets PF_SUPERPRIV in t->flags if the capability > > > > > is used. > > > > > > > > > > Do we care about these? > > > > > > > > Personally, not really, but I'll gladly put them back if you care. #2 > > > > seems more interesting to me than number 1. I actually kinda like > > > > getting EPERM from caps rather than EACCES since them I know if I was > > > > denied by selinux or by caps..... > > > > > > > > -Eric > > > > > > Yup, I asked bc I didn't particularly care myself. > > > > > > I think I agree with you about -EPERM being better anyway. However I > > > (now) think in this case PF_SUPERPRIV definately should be set, as this > > > is a clear use of a capability to do something that couldn't have been > > > done without it. > > > > On a related but different note, we should consider all current uses of > > cap_capable(), as they represent capability checks that will not be > > subject to a further restrictive check by other security modules. In > > this case and in the vm_enough_memory case, that is intentional, but not > > so clear for other uses in commoncap.c. > > Most of commoncap.c is called either as a secondary hook from the active > lsm (aka selinux calls the commoncap.c functions) or in the ! > CONFIG_SECURITY case. > > I'll audit this afternoon to see which of them might not fit these > rules.... That isn't what I meant. Most of the commoncap functions call capable() rather than directly calling cap_capable(), thereby causing: - PF_SUPERPRIV to be set, and - The primary security module (e.g. SELinux) to apply its own restrictive check. That is useful as it allows SELinux or AppArmor or TOMOYO to veto e.g. CAP_SYS_PTRACE without replicating the same logic within its own hook. The current exceptions are: cap_inh_is_capped() called from cap_capset(), cap_task_prctl() in the PR_SET_SECUREBITS case, cap_vm_enough_memory(), cap_file_mmap() after your patch. The latter two are indeed cases where we made a conscious choice that SELinux would not apply its capability check against policy. But the first two are unclear to me. -- Stephen Smalley National Security Agency -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@xxxxxxxxxxxxx with the words "unsubscribe selinux" without quotes as the message.
