On Thu, Dec 13, 2018 at 06:04:20AM -0500, Mimi Zohar wrote:

quoted

I don't have a problem with the concept, but we're running low on O_ bits.
Does this have to be done before the process gets a file descriptor,
or could we have a new syscall?  Since we're going to be changing the
interpreters anyway, it doesn't seem like too much of an imposition to
ask them to use:

	int verify_for_exec(int fd)

instead of adding an O_MAYEXEC.

The indication needs to be set during file open, before the open
returns to the caller.  This is the point where ima_file_check()
verifies the file's signature.  On failure, access to the file is
denied.

I understand that's what happens today, but do we need to do it that way?
There's no harm in the interpreter having an fd to a file if it knows
not to execute it.  This is different from a program opening a file and
having the LSM deny access to it because it violates the security model.