The set_ownership callback is not supposed to modify the ctl_table.
Enforce this expectation via the typesystem.

The patch was created with the following coccinelle script:

  virtual patch
  virtual context
  virtual report

  @@
  identifier func, head, table, uid, gid;
  @@

  void func(
    struct ctl_table_header *head,
  - struct ctl_table *table,
  + const struct ctl_table *table,
    kuid_t *uid, kgid_t *gid)
  { ... }

This change also is a step to put "struct ctl_table" into .rodata
throughout the kernel.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
The patch is meant to be merged via the sysctl tree.

This change was originally part of the sysctl-const series [0].
To slim down that series and reduce the message load on other
maintainers to a minimumble, submit this patch on its own.

[0] https://lore.kernel.org/lkml/20231204-const-sysctl-v2-2-7a5060b11447@weissschuh.net/
---
 include/linux/sysctl.h | 2 +-
 net/sysctl_net.c       | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 26a38161c28f..800154e1ff88 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -205,7 +205,7 @@ struct ctl_table_root {
 	struct ctl_table_set default_set;
 	struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
 	void (*set_ownership)(struct ctl_table_header *head,
-			      struct ctl_table *table,
+			      const struct ctl_table *table,
 			      kuid_t *uid, kgid_t *gid);
 	int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
 };
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index 051ed5f6fc93..1310ef8f0958 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -54,7 +54,7 @@ static int net_ctl_permissions(struct ctl_table_header *head,
 }
 
 static void net_ctl_set_ownership(struct ctl_table_header *head,
-				  struct ctl_table *table,
+				  const struct ctl_table *table,
 				  kuid_t *uid, kgid_t *gid)
 {
 	struct net *net = container_of(head->set, struct net, sysctls);

---
base-commit: de2ee5e9405e12600c81e39837362800cee433a2
change-id: 20231226-sysctl-const-ownership-ff75e67b4eea

Best regards,
-- 
Thomas Weißschuh <linux@weissschuh.net>

On Tue, Dec 26, 2023 at 01:32:42PM +0100, Thomas Weißschuh wrote:
> The set_ownership callback is not supposed to modify the ctl_table.
> Enforce this expectation via the typesystem.
> 
> The patch was created with the following coccinelle script:
> 
>   virtual patch
>   virtual context
>   virtual report

If you remove this virtual stuff and mention how we verify manually
through the build how users do not exits which rely on modifying the the
table I thinkt these two patches are ready, thanks for doing this in
Coccinelle it helps me review this faster!

  Luis

On 2023-12-28 05:22:56-0800, Luis Chamberlain wrote:
> On Tue, Dec 26, 2023 at 01:32:42PM +0100, Thomas Weißschuh wrote:
> > The set_ownership callback is not supposed to modify the ctl_table.
> > Enforce this expectation via the typesystem.
> > 
> > The patch was created with the following coccinelle script:
> > 
> >   virtual patch
> >   virtual context
> >   virtual report
> 
> If you remove this virtual stuff and mention how we verify manually
> through the build how users do not exits which rely on modifying the the
> table I thinkt these two patches are ready, thanks for doing this in
> Coccinelle it helps me review this faster!

Actually the 'table' parameter is never even used.
Do you prefer to drop it completely?


Thomas

On Fri, Feb 23, 2024 at 02:16:15PM +0100, Thomas Weißschuh wrote:
> On 2023-12-28 05:22:56-0800, Luis Chamberlain wrote:
> > On Tue, Dec 26, 2023 at 01:32:42PM +0100, Thomas Weißschuh wrote:
> > > The set_ownership callback is not supposed to modify the ctl_table.
> > > Enforce this expectation via the typesystem.
> > > 
> > > The patch was created with the following coccinelle script:
> > > 
> > >   virtual patch
> > >   virtual context
> > >   virtual report
> > 
> > If you remove this virtual stuff and mention how we verify manually
> > through the build how users do not exits which rely on modifying the the
> > table I thinkt these two patches are ready, thanks for doing this in
> > Coccinelle it helps me review this faster!
> 
> Actually the 'table' parameter is never even used.

Oh wow.

> Do you prefer to drop it completely?

Absolutely.

  Luis