Re: [PATCH v1 1/2] io_uring,audit: audit IORING_OP_FADVISE but not IORING_OP_MADVISE

On Fri, Jan 27, 2023 at 12:24 PM Richard Guy Briggs <rgb(a)redhat.com&gt; 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(a)redhat.com&gt; > --- > 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?

> [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.

paul-moore.com