stackleak: move stack_erasing sysctl to stackleak.c

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.

[mcgrof@kernel.org: commit log update]

Link: https://lkml.kernel.org/r/20211124231435.1445213-8-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Qing Wang <wangqing@vivo.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/stackleak.h b/include/linux/stackleak.h
index a59db2f08e76b7ea6804fdccaa03c3e817b9a9ea..ccaab2043fcd513febda43f1a1dc61d5062791ef 100644 (file)
--- 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 ce161a8e8d97585c8b1152fec1ea088343cf15d8..66b8af394e5891429433973a71722383febdd92f 100644 (file)
--- 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 b0cced3808d41e67b78bb364c3bc0b8c9b630ac6..3e06dafdd2c330591ddd0a606e88d1eb50545e38 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -95,9 +95,6 @@
 #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)
 
@@ -2442,17 +2439,6 @@ 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
        { }
 };