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Date: Mon, 11 Mar 2024 10:22:45 +0100
From: Joel Granados <j.granados@samsung.com>
To: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <linux@weissschuh.net>
CC: Luis Chamberlain <mcgrof@kernel.org>, Kees Cook <keescook@chromium.org>,
	"David S. Miller" <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	<linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
	<netdev@vger.kernel.org>
Subject: Re: [PATCH v2] sysctl: treewide: constify
 ctl_table_root::permissions
Message-ID: <20240311092245.geslwjlcrufw6bsb@joelS2.panther.com>
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References: <CGME20240223155229eucas1p24a18fa79cda02a703bcceff3bd38c2ba@eucas1p2.samsung.com>
	<20240223-sysctl-const-permissions-v2-1-0f988d0a6548@weissschuh.net>
	<20240303143408.sxrbd7pykmyhwu5f@joelS2.panther.com>
	<e3198416-4d90-4984-88ee-d2fccf96c783@t-8ch.de>

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On Sun, Mar 10, 2024 at 10:18:07AM +0100, Thomas Wei=DFschuh wrote:
> Hi!
>=20
> On 2024-03-03 15:34:08+0100, Joel Granados wrote:
> > Just to be sure I'm following. This is V2 of "[PATCH] sysctl: treewide:
> > constify ctl_table_root::set_ownership". Right? I ask, because the
> > subject changes slightly.
>=20
> No, the v1 of this patch is linked in the patch log below.
>=20
> The patches for ::set_ownership and ::permissions are changing two
> different callbacks and both of them are needed.
Awesome. thx for clarifying. So the ::permissions one I have reviewed
and have added to the constification branch in sysctl repo for testing.
I'm missing the review for the set_ownership one.

Best

>=20
> The v2 for set_ownership is here:
> https://lore.kernel.org/lkml/20240223-sysctl-const-ownership-v2-1-f9ba179=
5aaf2@weissschuh.net/
>=20
> Regards
>=20
> >=20
> > Best
> >=20
> > On Fri, Feb 23, 2024 at 04:52:16PM +0100, Thomas Wei=DFschuh wrote:
> > > The permissions callback is not supposed to modify the ctl_table.
> > > Enforce this expectation via the typesystem.
> > >=20
> > > The patch was created with the following coccinelle script:
> > >=20
> > >   @@
> > >   identifier func, head, ctl;
> > >   @@
> > >=20
> > >   int func(
> > >     struct ctl_table_header *head,
> > >   - struct ctl_table *ctl)
> > >   + const struct ctl_table *ctl)
> > >   { ... }
> > >=20
> > > (insert_entry() from fs/proc/proc_sysctl.c is a false-positive)
> > >=20
> > > The three changed locations were validated through manually inspection
> > > and compilation.
> > >=20
> > > In addition a search for '.permissions =3D' was done over the full tr=
ee to
> > > look for places that were missed by coccinelle.
> > > None were found.
> > >=20
> > > This change also is a step to put "struct ctl_table" into .rodata
> > > throughout the kernel.
> > >=20
> > > Signed-off-by: Thomas Wei=DFschuh <linux@weissschuh.net>
> > > ---
> > > To: Luis Chamberlain <mcgrof@kernel.org>
> > > To: Kees Cook <keescook@chromium.org>
> > > To: Joel Granados <j.granados@samsung.com>
> > > To: David S. Miller <davem@davemloft.net>
> > > Signed-off-by: Thomas Wei=DFschuh <linux@weissschuh.net>
> > >=20
> > > Changes in v2:
> > > - flesh out commit messages
> > > - Integrate changes to set_ownership and ctl_table_args into a single
> > >   series
> > > - Link to v1: https://lore.kernel.org/r/20231226-sysctl-const-permiss=
ions-v1-1-5cd3c91f6299@weissschuh.net
> > > ---
> > > The patch is meant to be merged via the sysctl tree.
> > >=20
> > > There is an upcoming series that will introduce a new implementation =
of
> > > .permission which would need to be adapted [0].
> > > The adaption would be trivial as the 'table' parameter also not modif=
ied
> > > there.
> > >=20
> > > This change was originally part of the sysctl-const series [1].
> > > To slim down that series and reduce the message load on other
> > > maintainers to a minimumble, submit this patch on its own.
> > >=20
> > > [0] https://lore.kernel.org/lkml/20240222160915.315255-1-aleksandr.mi=
khalitsyn@canonical.com/
> > > [1] https://lore.kernel.org/lkml/20231204-const-sysctl-v2-2-7a5060b11=
447@weissschuh.net/
> > > ---
> > >  include/linux/sysctl.h | 2 +-
> > >  ipc/ipc_sysctl.c       | 2 +-
> > >  kernel/ucount.c        | 2 +-
> > >  net/sysctl_net.c       | 2 +-
> > >  4 files changed, 4 insertions(+), 4 deletions(-)
> > >=20
> > > diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> > > index ee7d33b89e9e..0a55b5aade16 100644
> > > --- a/include/linux/sysctl.h
> > > +++ b/include/linux/sysctl.h
> > > @@ -207,7 +207,7 @@ struct ctl_table_root {
> > >  	void (*set_ownership)(struct ctl_table_header *head,
> > >  			      struct ctl_table *table,
> > >  			      kuid_t *uid, kgid_t *gid);
> > > -	int (*permissions)(struct ctl_table_header *head, struct ctl_table =
*table);
> > > +	int (*permissions)(struct ctl_table_header *head, const struct ctl_=
table *table);
> > >  };
> > > =20
> > >  #define register_sysctl(path, table)	\
> > > diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
> > > index 8c62e443f78b..b087787f608f 100644
> > > --- a/ipc/ipc_sysctl.c
> > > +++ b/ipc/ipc_sysctl.c
> > > @@ -190,7 +190,7 @@ static int set_is_seen(struct ctl_table_set *set)
> > >  	return &current->nsproxy->ipc_ns->ipc_set =3D=3D set;
> > >  }
> > > =20
> > > -static int ipc_permissions(struct ctl_table_header *head, struct ctl=
_table *table)
> > > +static int ipc_permissions(struct ctl_table_header *head, const stru=
ct ctl_table *table)
> > >  {
> > >  	int mode =3D table->mode;
> > > =20
> > > diff --git a/kernel/ucount.c b/kernel/ucount.c
> > > index 4aa6166cb856..90300840256b 100644
> > > --- a/kernel/ucount.c
> > > +++ b/kernel/ucount.c
> > > @@ -38,7 +38,7 @@ static int set_is_seen(struct ctl_table_set *set)
> > >  }
> > > =20
> > >  static int set_permissions(struct ctl_table_header *head,
> > > -				  struct ctl_table *table)
> > > +			   const struct ctl_table *table)
> > >  {
> > >  	struct user_namespace *user_ns =3D
> > >  		container_of(head->set, struct user_namespace, set);
> > > diff --git a/net/sysctl_net.c b/net/sysctl_net.c
> > > index 051ed5f6fc93..ba9a49de9600 100644
> > > --- a/net/sysctl_net.c
> > > +++ b/net/sysctl_net.c
> > > @@ -40,7 +40,7 @@ static int is_seen(struct ctl_table_set *set)
> > > =20
> > >  /* Return standard mode bits for table entry. */
> > >  static int net_ctl_permissions(struct ctl_table_header *head,
> > > -			       struct ctl_table *table)
> > > +			       const struct ctl_table *table)
> > >  {
> > >  	struct net *net =3D container_of(head->set, struct net, sysctls);
> > > =20
> > >=20
> > > ---
> > > base-commit: ffd2cb6b718e189e7e2d5d0c19c25611f92e061a
> > > change-id: 20231226-sysctl-const-permissions-d7cfd02a7637
> > >=20
> > > Best regards,
> > > --=20
> > > Thomas Wei=DFschuh <linux@weissschuh.net>
> > >=20
> >=20
> > --=20
> >=20
> > Joel Granados
>=20
>=20

--=20

Joel Granados

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