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From: Steve Grubb <[email protected]>
To: Jens Axboe <[email protected]>, Paul Moore <[email protected]>
Cc: Richard Guy Briggs <[email protected]>,
	Linux-Audit Mailing List <[email protected]>,
	LKML <[email protected]>,
	[email protected], Eric Paris <[email protected]>,
	Stefan Roesch <[email protected]>,
	Christian Brauner <[email protected]>,
	Pavel Begunkov <[email protected]>
Subject: Re: [PATCH v1 1/2] io_uring,audit: audit IORING_OP_FADVISE but not IORING_OP_MADVISE
Date: Sat, 28 Jan 2023 11:48:55 -0500	[thread overview]
Message-ID: <5911706.lOV4Wx5bFT@x2> (raw)
In-Reply-To: <CAHC9VhSfG6Oddk3qeFYiwkE5orRKs_PCLAD+F0yK-fRx27UTwg@mail.gmail.com>

On Friday, January 27, 2023 5:57:30 PM EST Paul Moore wrote:
> On Fri, Jan 27, 2023 at 5:45 PM Jens Axboe <[email protected]> wrote:
> > On 1/27/23 3:35?PM, Paul Moore wrote:
> > > On Fri, Jan 27, 2023 at 12:24 PM Richard Guy Briggs <[email protected]> 
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
> > >> <[email protected]>
> > >> ---
> > >> 
> > >>  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?
> 
> That was my thought too when I was looking at it.

Oh. Yeah. fallocate is the one that truncates. fadvise can be skipped.

-Steve

> > 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.
> 
> Agreed on the fadvise side, and probably the madvise side too,
> although the latter has more options/code to sift through so I'm
> curious to hear what analysis Richard has done on that one.





  reply	other threads:[~2023-01-28 16:49 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-27 17:23 [PATCH v1 0/2] two suggested iouring op audit updates Richard Guy Briggs
2023-01-27 17:23 ` [PATCH v1 1/2] io_uring,audit: audit IORING_OP_FADVISE but not IORING_OP_MADVISE Richard Guy Briggs
2023-01-27 22:35   ` Paul Moore
2023-01-27 22:45     ` Jens Axboe
2023-01-27 22:57       ` Paul Moore
2023-01-28 16:48         ` Steve Grubb [this message]
2023-01-27 23:02       ` Richard Guy Briggs
2023-01-27 23:03         ` Jens Axboe
2023-01-27 23:08           ` Richard Guy Briggs
2023-01-27 22:55     ` Richard Guy Briggs
2023-01-27 23:05       ` Paul Moore
2023-01-27 17:23 ` [PATCH v1 2/2] io_uring,audit: do not log IORING_OP_*GETXATTR Richard Guy Briggs
2023-01-27 22:43   ` Paul Moore
2023-01-27 23:01     ` Richard Guy Briggs
2023-01-27 23:05       ` Jens Axboe
2023-01-28  0:07         ` Paul Moore
2023-01-28  0:06       ` Paul Moore
2023-01-28  0:19         ` Richard Guy Briggs
2023-01-28 17:26     ` Steve Grubb
2023-01-29 23:37       ` Paul Moore
2023-01-27 17:40 ` [PATCH v1 0/2] two suggested iouring op audit updates Jens Axboe
2023-01-27 19:42   ` Paul Moore
2023-01-27 19:43     ` Jens Axboe
2023-01-27 22:38       ` Paul Moore
2023-01-27 22:46         ` Jens Axboe
2023-01-27 22:53           ` Paul Moore
2023-01-27 23:02             ` Jens Axboe
2023-01-27 23:07               ` Richard Guy Briggs
2023-01-27 23:08               ` Paul Moore
2023-01-27 23:10                 ` Jens Axboe
2023-01-28 16:47             ` Steve Grubb
2023-01-28 17:03               ` Paul Moore

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