On 1/20/2015 3:17 PM, James Morris wrote: > On Sat, 17 Jan 2015, Ben Hutchings wrote: > >> chown() and write() should clear all privilege attributes on >> a file - setuid, setgid, setcap and any other extended >> privilege attributes. >> >> However, any attributes beyond setuid and setgid are managed by the >> LSM and not directly by the filesystem, so they cannot be set along >> with the other attributes. >> >> Currently we call security_inode_killpriv() in notify_change(), >> but in case of a chown() this is too early - we have not called >> inode_change_ok() or made any filesystem-specific permission/sanity >> checks. >> >> Add a new function setattr_killpriv() which calls >> security_inode_killpriv() if necessary, and change the setattr() >> implementation to call this in each filesystem that supports xattrs. >> This assumes that extended privilege attributes are always stored in >> xattrs. > It'd be useful to get some input from LSM module maintainers on this.
I've already chimed in. Clearing the Smack label on a file because someone writes to it makes no sense whatsoever. The same with chown. The Smack label is attached to the object, which is a container of data, not the data itself. Smack labels are Mandatory Access Control labels, not Information labels. If that doesn't mean anything to the reader, check out the P1003.1e/2c (withdrawn) DRAFT. The proposed implementation does not correctly handle either Mandatory Access Control labels or Information labels. The MAC label is *very different* from the setuid bit. > > e.g. doesn't SELinux already handle this via policy directives? > > -- To UNSUBSCRIBE, email to debian-bugs-rc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
