Casey Schaufler wrote: > Serge E. Hallyn wrote: > >> Quoting Eric Paris (eparis@xxxxxxxxxx): >> >> >>> 3) I've also heard it hinted that we could do this with audit by just >>> having audit drop the denials that include the access(2) syscall and the >>> scontext and tcontext for the slew of things the SELinux policy writers >>> know we are not interested in. And while it seems good, now we have >>> >>> >> What is the difference whether an attacker does access(2) to check for >> /etc/shadow rights, or does a failed open()? >> >> > > I have been studiously ignoring the discussions on the SELinux list because > in the end it really doesn't matter, as Serge (appears to) point out here. > The access() system call was a major thorn in the side of the POSIX security > working group because its behavior is not really very rational. By design > it does not take into account read-only file systems, ACLs, MAC labels, > TOMOYO policy, or anything other than the mode bits. A successful return > from access() gives you no assurance whatever that if you actually try the > operation it will succeed. My recollection is that every version of > "trusted unix" written treats the system call the same way it would a > call to lstat(), because that's really all it is doing. > Serge, and the status quo, says access() == open(), not access() == lstat(). Eric's proposed change would be necessary to support access() == lstat(), even as an option. -- Eamon Walsh <ewalsh@xxxxxxxxxxxxx> National Security Agency -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
