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

On 2023-01-27 15:45, Jens Axboe wrote: > On 1/27/23 3:35?PM, Paul Moore wrote: >> 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? > > Yeah, honestly not sure where that came from. Maybe it's being mixed up > with fallocate? All fadvise (or madvise, for that matter) does is > provide hints on the caching or access pattern. On second thought, both > of these should be able to set audit_skip as far as I can tell. That was one suspicion I had. If this is the case, I'd agree both could be skipped.