Re: [PATCH 05/14] sysctl: Add a size arg to __register_sysctl_table

From: Joel Granados <j.granados@samsung.com>
To: Simon Horman <horms@kernel.org>
Cc: <mcgrof@kernel.org>, Kees Cook <keescook@chromium.org>,
	Iurii Zaikin <yzaikin@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	<willy@infradead.org>, <josh@joshtriplett.org>,
	<linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
	<netdev@vger.kernel.org>
Subject: Re: [PATCH 05/14] sysctl: Add a size arg to __register_sysctl_table
Date: Fri, 28 Jul 2023 18:08:22 +0200	[thread overview]
Message-ID: <20230728160822.4dh3asnao2l4bdwx@localhost> (raw)
In-Reply-To: <ZMOdqvMfyPkNYBoq@kernel.org>

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On Fri, Jul 28, 2023 at 12:51:22PM +0200, Simon Horman wrote:
> On Wed, Jul 26, 2023 at 04:06:25PM +0200, Joel Granados wrote:
> > This is part of the effort to remove the sentinel element in the
> > ctl_table arrays. We add a table_size argument to
> > __register_sysctl_table and adjust callers, all of which pass ctl_table
> > pointers and need an explicit call to ARRAY_SIZE.
> > 
> > The new table_size argument does not yet have any effect in the
> > init_header call which is still dependent on the sentinel's presence.
> > table_size *does* however drive the `kzalloc` allocation in
> > __register_sysctl_table with no adverse effects as the allocated memory
> > is either one element greater than the calculated ctl_table array (for
> > the calls in ipc_sysctl.c, mq_sysctl.c and ucount.c) or the exact size
> > of the calculated ctl_table array (for the call from sysctl_net.c and
> > register_sysctl). This approach will allows us to "just" remove the
> > sentinel without further changes to __register_sysctl_table as
> > table_size will represent the exact size for all the callers at that
> > point.
> > 
> > Temporarily implement a size calculation in register_net_sysctl, which
> > is an indirection call for all the network register calls.
> > 
> > Signed-off-by: Joel Granados <j.granados@samsung.com>
> > ---
> >  fs/proc/proc_sysctl.c  | 22 +++++++++++-----------
> >  include/linux/sysctl.h |  2 +-
> >  ipc/ipc_sysctl.c       |  4 +++-
> >  ipc/mq_sysctl.c        |  4 +++-
> >  kernel/ucount.c        |  3 ++-
> >  net/sysctl_net.c       |  8 +++++++-
> >  6 files changed, 27 insertions(+), 16 deletions(-)
> > 
> > diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> > index fa1438f1a355..8d04f01a89c1 100644
> > --- a/fs/proc/proc_sysctl.c
> > +++ b/fs/proc/proc_sysctl.c
> > @@ -1354,27 +1354,20 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
> >   */
> >  struct ctl_table_header *__register_sysctl_table(
> >  	struct ctl_table_set *set,
> > -	const char *path, struct ctl_table *table)
> > +	const char *path, struct ctl_table *table, size_t table_size)
> 
> Hi Joel,
> 
> Please consider adding table_size to the kernel doc for this function.
Good catch. Will do for V2.
> 
> ...

-- 

Joel Granados

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