[PATCH v2 7/8] stackleak: move stack_erasing sysctl to stackleak.c

Luis Chamberlain
2021-11-24T23:15:21Z

From: Xiaoming Ni <nixiaoming@huawei.com>

The kernel/sysctl.c is a kitchen sink where everyone leaves
their dirty dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to
places where they actually belong. The proc sysctl maintainers
do not want to know what sysctl knobs you wish to add for your own
piece of code, we just care about the core logic.

So move the stack_erasing sysctl from kernel/sysctl.c to
kernel/stackleak.c and use register_sysctl() to register the
sysctl interface.

Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
[mcgrof: commit log update]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
include/linux/stackleak.h | 5 -----
kernel/stackleak.c | 26 ++++++++++++++++++++++++--
kernel/sysctl.c | 14 --------------
3 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/include/linux/stackleak.h b/include/linux/stackleak.h
index a59db2f08e76..ccaab2043fcd 100644
--- a/include/linux/stackleak.h
+++ b/include/linux/stackleak.h
@@ -23,11 +23,6 @@ static inline void stackleak_task_init(struct task_struct *t)
# endif
}

-#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
-int stack_erasing_sysctl(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos);
-#endif
-
#else /* !CONFIG_GCC_PLUGIN_STACKLEAK */
static inline void stackleak_task_init(struct task_struct *t) { }
#endif
diff --git a/kernel/stackleak.c b/kernel/stackleak.c
index ce161a8e8d97..66b8af394e58 100644
--- a/kernel/stackleak.c
+++ b/kernel/stackleak.c
@@ -16,11 +16,13 @@
#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
#include <linux/jump_label.h>
#include <linux/sysctl.h>
+#include <linux/init.h>

static DEFINE_STATIC_KEY_FALSE(stack_erasing_bypass);

-int stack_erasing_sysctl(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
+#ifdef CONFIG_SYSCTL
+static int stack_erasing_sysctl(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
{
int ret = 0;
int state = !static_branch_unlikely(&stack_erasing_bypass);
@@ -42,6 +44,26 @@ int stack_erasing_sysctl(struct ctl_table *table, int write,
state ? "enabled" : "disabled");
return ret;
}
+static struct ctl_table stackleak_sysctls[] = {
+ {
+ .procname = "stack_erasing",
+ .data = NULL,
+ .maxlen = sizeof(int),
+ .mode = 0600,
+ .proc_handler = stack_erasing_sysctl,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+ {}
+};
+
+static int __init stackleak_sysctls_init(void)
+{
+ register_sysctl_init("kernel", stackleak_sysctls);
+ return 0;
+}
+late_initcall(stackleak_sysctls_init);
+#endif /* CONFIG_SYSCTL */

#define skip_erasing() static_branch_unlikely(&stack_erasing_bypass)
#else
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index a4bda4a11ea8..5812d76ecee1 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -94,9 +94,6 @@
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_LOCK_STAT)
#include <linux/lockdep.h>
#endif
-#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
-#include <linux/stackleak.h>
-#endif

#if defined(CONFIG_SYSCTL)

@@ -2441,17 +2438,6 @@ static struct ctl_table kern_table[] = {
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_INT_MAX,
},
-#endif
-#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
- {
- .procname = "stack_erasing",
- .data = NULL,
- .maxlen = sizeof(int),
- .mode = 0600,
- .proc_handler = stack_erasing_sysctl,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
#endif
{ }
};
--
2.33.0