Quoting Casey Schaufler (casey@xxxxxxxxxxxxxxxx): > Serge E. Hallyn wrote: > > Quoting Stephen Smalley (sds@xxxxxxxxxxxxx): > > > >> On Tue, 2009-03-17 at 12:39 -0500, Serge E. Hallyn wrote: > >> > >>> Quoting Stephen Smalley (sds@xxxxxxxxxxxxx): > >>> > >>>>> So do you think it makes sense to have CAP_MAC_ADMIN and CAP_FOWNER > >>>>> in CAP_FS_MASK? In other words are you objecting to CAP_SYS_ADMIN > >>>>> because of all of its other implications, or because you disagree > >>>>> that labels for security modules should be treated as mere fs data > >>>>> here? > >>>>> > >>>> For CAP_FOWNER, yes (and it is already there). CAP_MAC_ADMIN is less > >>>> > >>> Sorry, I meant CAP_SETFCAP. Should it be added? > >>> > >> Sure - it is only used for filesystem operations. > >> > > > > Ok, so then: > > > > > >>>> ideal as it isn't clearly tied to filesystem accesses, and likewise for > >>>> CAP_MAC_OVERRIDE (but that one is included in CAP_FS_MASK already). > >>>> > >>> So it is. I didn't realize that. > >>> > >>> > >>>> Ideally the capability space would be partitioned into capabilities that > >>>> affect filesystem accesses and the rest so that setfsuid() would yield > >>>> the expected behavior of only affecting filesystem access. > >>>> CAP_SYS_ADMIN is even less suitable due to its pervasive use outside of > >>>> the filesystem. So that's the first concern. > >>>> > >>>> The second one is that we don't want CAP_SYS_ADMIN (or CAP_MAC_ADMIN) to > >>>> be required when setting SELinux labels. Only the SELinux permission > >>>> checks should govern setting those labels (aside from the usual DAC > >>>> ownership || CAP_FOWNER check). > >>>> > >>> So if a non-selinux kernel is booted, then you think only the usual > >>> DAC checks should be required to set selinux labels? > >>> > >> I'm talking about the dumb NFS server case (non-SELinux NFS server > >> providing label and data storage to SELinux clients, MAC enforcement > >> handled client-side). But we aren't there yet, so I don't think we have > >> to worry about it right now. > >> > > > > But in cap_inode_setxattr, any security.* xattrs are controlled by > > CAP_SYS_ADMIN. So do you think that this should be changed to a > > CAP_XATTR_SECURITY capability which can be added to CAP_FS_MASK? > > > > Hum. The intention of CAP_MAC_ADMIN was that it control the explicit > setting of the access control attributes used by the Smack LSM. I > personally prefer a single capability for the action over multiple > capabilities based on the objects involved. If you introduce > CAP_XATTR_SECURITY I would think that CAP_PROC_XATTR, > CAP_SVIPC_XATTR, CAP_NETWORK_XATTR, ... would follow in short order > and I hate the idea of having hundreds of capabilities. If you > must decouple the capability from MAC, how about a new name? Oh I didn't say that we must, I'm just trying to figure out what we want to do in the case that a security.foo xattr is being set, and the foo LSM is not compiled in. What is being done right now is that CAP_SYS_ADMIN is required to do the setting, and so doing setresuid(500,500,0); setfsuid(0); setxattr(somefilename, "security.SMACK64", LABEL, sizeof(LABEL), 0); will fail the setxattr. -serge -- 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.
