On Thu, 2019-01-17 at 16:47 -0800, Casey Schaufler wrote:
> security_inode_init_security() currently calls at most one
> of selinux_inode_init_security() and smack_inode_init_security().
> It then sends the result to evm_inode_init_security to create
> the security.evm attribute. This isn't going to work on a system
> that has both SELinux and Smack.
Calculating security.evm based on multiple xattrs sounded really
familiar. Looking back at the git log, 9d8f13ba3f48 ("security: new
security_inode_init_security API adds function callback") addressed
filesystems wanting to be able to write all the xattrs at the same
time and prepared for multiple LSM xattr support.
> I see two options:
> - create security.evm with the information from all
> security modules that provide inode_init_security hooks
> - create a separate attribute for each module,
> security.evm-selinux and security.evm-smack in the
> current case.
>
> How would you like to have it work? I am agnostic, although the
> separate attributes would be easier for the infrastructure.
Having separate attributes for each LSM module would require re-
calculating the hmac for each one, any time any of the other file
metadata changed. That doesn't sound like a good idea.
Mimi
