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bh=E+HX08I7hcmZbTcMtII8s3Be0mGGLDDFpjX+MYdbh3c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=bweBo8pjfSv8AYcDwRpn1DgozRF8dZfqj32ZRKwVbXH+Wh8BA/ib6tg9bnjMe2poT 5AKG9lmosmdIXWrr3rehhq4C5T6WmV/iwXOw+GZCKHNHw5I4JYqWjmktIz/0Z/kYkl QNDn1BZgBoFt9/lLfnwjbLWcIoxhXvXder64zE8M= Date: Fri, 16 Dec 2022 09:42:59 -0800 From: Andrew Morton To: Jeff Xu Cc: Peter Xu , Kees Cook , jeffxu@chromium.org, skhan@linuxfoundation.org, dmitry.torokhov@gmail.com, dverkamp@chromium.org, hughd@google.com, jorgelo@chromium.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, jannh@google.com, linux-hardening@vger.kernel.org, kernel test robot Subject: Re: [PATCH v6 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC Message-Id: <20221216094259.bec91e4abd6cf54a05ce2813@linux-foundation.org> In-Reply-To: References: <20221207154939.2532830-1-jeffxu@google.com> <20221207154939.2532830-4-jeffxu@google.com> <202212080821.5AE7EE99@keescook> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: fa37tqyddy5u9ikmtcpabh5zw6z6ajxc X-Rspam-User: X-Rspamd-Queue-Id: 52CFF40011 X-Rspamd-Server: rspam06 X-HE-Tag: 1671212584-708395 X-HE-Meta: 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 O+2QYh9P rgBDfii0lqTgcei2qRgn7H4PTXt7SV40SqKGAOsqSC9QUxSsq+ybpS812NWQqr9WGKbvoMwWMne6Ax+F6IgKQgg5OzBMgAYFmD14xko3ReTmwmcHzWVuVSS2wOetlBGB97UlDB2jGaLU8iTO9FXzY8+IXnx+8T08id2+WgOK9zZ+CngSxqHvdO3pJ9JGoD8eG+vuk X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 16 Dec 2022 09:15:40 -0800 Jeff Xu wrote: > On Fri, Dec 16, 2022 at 7:47 AM Peter Xu wrote: > > > > Hi, Jeff, > > > > On Thu, Dec 08, 2022 at 02:55:45PM -0800, Jeff Xu wrote: > > > > > + if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) { > > > > [...] > > > > > > > + pr_warn_ratelimited( > > > > > + "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n", > > > > > + task_pid_nr(current), get_task_comm(comm, current)); > > > > This will be frequently dumped right now with mm-unstable. Is that what it > > wanted to achieve? > > > > [ 10.822575] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=491 'systemd' > > [ 10.824743] memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=495 '(sd-executor)' > > ... > > > > If there's already a sane default value (and also knobs for the user to > > change the default) not sure whether it's saner to just keep it silent as > > before? > > > Thanks for your comments. > > The intention is it is a reminder to adjust API calls to explicitly > setting this bit. Do we need to warn more than once per boot? If not, use pr_warn_once()? > The sysctl vm.memfd_noexec = 0 1 is for transaction to the final > state, and 2 depends on API call setting this bit. > > The log is ratelimited, and there is a rate limit setting: > /proc/sys/kernel/printk_ratelimit > /proc/sys/kernel/printk_ratelimit_burst >