From: Aleksa Sarai <cyphar@cyphar.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Damian Tometzki <dtometzki@fedoraproject.org>,
Shuah Khan <shuah@kernel.org>, Jeff Xu <jeffxu@google.com>,
Kees Cook <keescook@chromium.org>,
Daniel Verkamp <dverkamp@chromium.org>,
Christian Brauner <brauner@kernel.org>,
Dominique Martinet <asmadeus@codewreck.org>,
stable@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v2 3/5] memfd: improve userspace warnings for missing exec-related flags
Date: Mon, 4 Sep 2023 17:09:09 +1000 [thread overview]
Message-ID: <20230904.070506-tidy.dividend.mousy.flasks-BFYX3RqFch3q@cyphar.com> (raw)
In-Reply-To: <20230902155850.ca1d32c16862cbe54ebd36ef@linux-foundation.org>
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On 2023-09-02, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Fri, 1 Sep 2023 07:13:45 +0200 Damian Tometzki <dtometzki@fedoraproject.org> wrote:
>
> > > if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
> > > - pr_warn_once(
> > > + pr_info_ratelimited(
> > > "%s[%d]: memfd_create() called without MFD_EXEC or MFD_NOEXEC_SEAL set\n",
> > > current->comm, task_pid_nr(current));
> > > }
> > >
> > > --
> > > 2.41.0
> > >
> > Hello Sarai,
> >
> > i got a lot of messages in dmesg with this. DMESG is unuseable with
> > this.
> > [ 1390.349462] __do_sys_memfd_create: 5 callbacks suppressed
> > [ 1390.349468] pipewire-pulse[2930]: memfd_create() called without MFD_EXEC or MFD_NOEXEC_SEAL set
> > [ 1390.350106] pipewire[2712]: memfd_create() called without MFD_EXEC or MFD_NOEXEC_SEAL set
>
> OK, thanks, I'll revert this. Spamming everyone even harder isn't a
> good way to get developers to fix their stuff.
Sorry, I'm on vacation. I will send a follow-up patch to remove this
logging entirely -- if we can't do rate-limited logging then logging a
single message effectively at boot time makes no sense. I had hoped that
this wouldn't be too much (given there is a fair amount of INFO-level
spam in the kernel log) but I guess the default ratelimit (5Hz) is too
liberal.
Perhaps we can re-consider adding some logging in the future, when more
programs have migrated. The only other "reasonable" way to reduce the
logging would be to add something to task_struct so we only log once per
task, but obviously that's massively overkill.
(FWIW, I don't think the logging was ever necessary. There's nothing
wrong with running an older program that doesn't pass the flags.)
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
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next prev parent reply other threads:[~2023-09-04 7:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-14 8:40 [PATCH v2 0/5] memfd: cleanups for vm.memfd_noexec Aleksa Sarai
2023-08-14 8:40 ` [PATCH v2 1/5] selftests: memfd: error out test process when child test fails Aleksa Sarai
2023-08-14 8:40 ` [PATCH v2 2/5] memfd: do not -EACCES old memfd_create() users with vm.memfd_noexec=2 Aleksa Sarai
2023-08-14 8:40 ` [PATCH v2 3/5] memfd: improve userspace warnings for missing exec-related flags Aleksa Sarai
2023-08-22 9:10 ` Christian Brauner
2023-09-01 5:13 ` Damian Tometzki
2023-09-02 22:58 ` Andrew Morton
2023-09-04 7:09 ` Aleksa Sarai [this message]
2023-09-05 16:20 ` Florian Weimer
2023-09-06 6:58 ` Aleksa Sarai
2023-08-14 8:41 ` [PATCH v2 4/5] memfd: replace ratcheting feature from vm.memfd_noexec with hierarchy Aleksa Sarai
2023-08-16 5:13 ` Jeff Xu
2023-08-16 5:44 ` Dominique Martinet
2023-08-16 22:46 ` Jeff Xu
2023-08-14 8:41 ` [PATCH v2 5/5] selftests: improve vm.memfd_noexec sysctl tests Aleksa Sarai
2023-08-16 5:08 ` [PATCH v2 0/5] memfd: cleanups for vm.memfd_noexec Jeff Xu
2023-08-19 2:50 ` Aleksa Sarai
2023-08-21 19:04 ` Jeff Xu
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