On Tue, 2008-10-21 at 02:12 +0100, Phillip Lougher wrote: > David P. Quigley wrote: > > Looking through the code I see two references to xattrs, one is the > > index of the xattr table in the superblock and there seems to be struct > > member in one of the inode structures that is an index into this table. > > Looking through the code I don't see either of these used at all. Do you > > intend to add xattr support at some point? I saw reference to the desire > > to add xattr support in an email from 2004 but you said that the code > > has been rewritten since then. If you are going to add xattr support you > > probably want to add it to more than just regular files. In SELinux and > > other LSMs symlinks and directories are also labeled so they will need > > xattr entries. > > Yes and yes. I am intending to add xattr support, something that's been > on my to-do list for a long time (since 2004 as you said), but it's been > something which I've never got the time to do. Once (if) Squashfs is > mainlined, it will be the next thing. > > The xattr references in the layout is my attempt at forward planning to > avoid making an incompatible layout change when I finally get around to > implementing it. My plan is to put xattrs in a table (referenced by the > superblock), and then put indexes in "extended" inodes which index > into the table (as you noticed). The general idea in Squashfs is that > inodes get optimised for normally occurring cases, and less common cases > (that would need a bigger inode) get to use an extended inode. > Squashfs currently has an extended regular file inode, which is where > the xattr index will sit, and so this has had an xattr index added. The > other inodes don't currently have extended inodes, these will be defined > when I implement xattrs (which is why they're missing). > > Having said that, I've fscked up and forgotten to add an xattr field to > the extended directory inode which is currently defined :) > > Thanks for spotting this. Just to clarify: When using a labeled MAC solution like SELinux or SMACK, every file (of every type, including device nodes, symlinks, fifos, etc) will have a security attribute on it. In the case of ext3, we have benefited from inlining of small attributes into the inode. -- Stephen Smalley National Security Agency -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
