On Wed, 2013-01-16 at 13:28 -0500, Vivek Goyal wrote: > On Wed, Jan 16, 2013 at 01:08:35PM -0500, Mimi Zohar wrote: > > On Wed, 2013-01-16 at 11:34 -0500, Vivek Goyal wrote: > > > > > I read the comment in ima_bprm_check() being called from > > > security_bprm_check(). > > > It says that files already open for write can't executed and files already > > > open for exec can't be open for writes. That's fine. > > > > > > I was worried about anonymous pages being modified on swap and then > > > faulted back in. It is not necessarily signature verification but making > > > sure signed processes memory is not modified later by any unsigned process > > > in anyway. And that includes disabling ptrace too. > > > > > > So IMA stuff does not do anything to protect against process memory being > > > modified using ptrace or by playing tricks with swap. > > > > > I am not sure what will happen if I can bypass the file system and > > > directly > > > write on a disk block and modify executable. (Assuming one can get block > > > information somehow). Does anything protect such modification? Will IMA > > > detect it? > > > > Sorry, this is out of scope for IMA. Dmitry has looked into this, but > > I'm not sure where it stands at the moment. > > Ok, so that's one reason that why I wrote these patcehs. IMA currently > is not doing following things to make sure address space of signed images > is not modified by others. > > - Protecting against modifications to pages on swap. > - Protecting against modifications by ptrace. > - Protecting against modifications which bypassed filesystem and directly > wrote to the block. > > Locking down all the pages of signed binaries in memory hopefully should > solve above problems.
Signing and verifying ELF executables goes back a long time ~2003/4, from a number of esteemed kernel developers, including Greg-KH and Serge Hallyn. IMA-appraisal isn't limited to appraising a single type of file, but is a generic mechanism for appraising all files. If there are issues that aren't being addressed, then by all means, please help by addressing them. Duplicating a large portion of the code is not productive. thanks, Mimi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
