The permissions callback is not supposed to modify the ctl_table.
Enforce this expectation via the typesystem.
The patch was created with the following coccinelle script:
@@
identifier func, head, ctl;
@@
int func(
struct ctl_table_header *head,
- struct ctl_table *ctl)
+ const struct ctl_table *ctl)
{ ... }
(insert_entry() from fs/proc/proc_sysctl.c is a false-positive)
The three changed locations were validated through manually inspection
and compilation.
In addition a search for '.permissions =' was done over the full tree to
look for places that were missed by coccinelle.
None were found.
This change also is a step to put "struct ctl_table" into .rodata
throughout the kernel.
Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
To: Luis Chamberlain <mcgrof@xxxxxxxxxx>
To: Kees Cook <keescook@xxxxxxxxxxxx>
To: Joel Granados <j.granados@xxxxxxxxxxx>
To: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
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-permissions-v1-1-5cd3c91f6299@xxxxxxxxxxxxxx
---
The patch is meant to be merged via the sysctl tree.
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 modified
there.
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.
[0] https://lore.kernel.org/lkml/20240222160915.315255-1-aleksandr.mikhalitsyn@xxxxxxxxxxxxx/
[1] https://lore.kernel.org/lkml/20231204-const-sysctl-v2-2-7a5060b11447@xxxxxxxxxxxxxx/
---
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(-)
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);
};
#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 ¤t->nsproxy->ipc_ns->ipc_set == set;
}
-static int ipc_permissions(struct ctl_table_header *head, struct ctl_table *table)
+static int ipc_permissions(struct ctl_table_header *head, const struct ctl_table *table)
{
int mode = table->mode;
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)
}
static int set_permissions(struct ctl_table_header *head,
- struct ctl_table *table)
+ const struct ctl_table *table)
{
struct user_namespace *user_ns =
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)
/* 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 = container_of(head->set, struct net, sysctls);
---
base-commit: ffd2cb6b718e189e7e2d5d0c19c25611f92e061a
change-id: 20231226-sysctl-const-permissions-d7cfd02a7637
Best regards,
--
Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
