security and trusted extended attributes into the -mm kernel

[Steven French]

> jfs adds security and trusted extended attributes into the -mm kernel

I see the corresponding patch 
(http://jfs.bkbits.net:8080/linux-2.5/gnupatch@41ae4315obsBp8r9Y0EzmG870QJhFA) 
on bitkeeper. 
Do you have some additional context explaining this and what they are for 
beyond the minimal info in man 5 attr? 

It sounds like something I need to do add to the cifs client too (and 
probably something smbd needs to be aware of) but ... the "security." and 
"trusted." namespace certainly would have different security 
considerations than the user. category which is the only one which I map 
to OS/2 EAs on the wire for Samba.   I don't really want to overuse the EA 
call for other namespace if it opens a security issue (namespace prefix 
"os2." and "user." are stripped off by the client and sent to the Samba 
server as EAs).   This is tricky because the ACL model which Samba knows 
about has a concept of who is granted permission in ACEs for modifying EAs 
and modifying the ACL but not sure how authorization for these two would 
be handled from the point of view of the server side ACL

Perhaps the best approach is to make another minor CIFS POSIX extension (a 
one-off of current set extended attributes) to handle these two namespaces 
- at least based on my read of man attr(5) and the security implications 
of these two.

Opinions?




Steve French
Senior Software Engineer
Linux Technology Center - IBM Austin
phone: 512-838-2294
email: sfrench at-sign us dot ibm dot co>