On 2023-01-27 17:35, Paul Moore wrote:
> On Fri, Jan 27, 2023 at 12:24 PM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> >
> > Since FADVISE can truncate files and MADVISE operates on memory, reverse
> > the audit_skip tags.
> >
> > Fixes: 5bd2182d58e9 ("audit,io_uring,io-wq: add some basic audit support to io_uring")
> > Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> > ---
> > io_uring/opdef.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/io_uring/opdef.c b/io_uring/opdef.c
> > index 3aa0d65c50e3..a2bf53b4a38a 100644
> > --- a/io_uring/opdef.c
> > +++ b/io_uring/opdef.c
> > @@ -306,12 +306,12 @@ const struct io_op_def io_op_defs[] = {
> > },
> > [IORING_OP_FADVISE] = {
> > .needs_file = 1,
> > - .audit_skip = 1,
> > .name = "FADVISE",
> > .prep = io_fadvise_prep,
> > .issue = io_fadvise,
> > },
>
> I've never used posix_fadvise() or the associated fadvise64*()
> syscalls, but from quickly reading the manpages and the
> generic_fadvise() function in the kernel I'm missing where the fadvise
> family of functions could be used to truncate a file, can you show me
> where this happens? The closest I can see is the manipulation of the
> page cache, but that shouldn't actually modify the file ... right?
I don't know. I was going on the advice of Steve Grubb. I'm looking
for feedback, validation, correction, here.
> > [IORING_OP_MADVISE] = {
> > + .audit_skip = 1,
> > .name = "MADVISE",
> > .prep = io_madvise_prep,
> > .issue = io_madvise,
>
> I *think* this should be okay, what testing/verification have you done
> on this? One of the things I like to check is to see if any LSMs
> might perform an access check and/or generate an audit record on an
> operation, if there is a case where that could happen we should setup
> audit properly. I did a very quick check of do_madvise() and nothing
> jumped out at me, but I would be interested in knowing what testing or
> verification you did here.
No testing other than build/boot/audit-testsuite. You had a test you
had developed that went through several iterations?
> paul-moore.com
- RGB
--
Richard Guy Briggs <rgb@xxxxxxxxxx>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
