On Mon, May 8, 2017 at 8:41 PM, Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > On Mon, May 08, 2017 at 12:17:53AM +0200, Jann Horn wrote: >> On Sun, May 7, 2017 at 5:58 PM, Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: >> > Document the new GETFSMAP ioctl that returns the physical layout of a >> > (disk-based) filesystem. [...] >> Also: From a quick glance at the XFS implementation, I don't see any >> privilege checks. Am I missing something, or does this API permit an >> unprivileged user to determine the number of physical blocks allocated >> for any inode, even for inodes the user can't ordinarily see in any >> way? > > Correct. What's your reasoning for why this doesn't create any new potential security issues? For example, as far as I can tell, this would permit an unprivileged user to determine with high probability whether a set of large files with known sizes is stored anywhere in the filesystem, even across containers or so.
