linux-hardening - [PATCH 5.10 02/20] kernel/panic: move panic sysctls to its own file

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Message-Id: <20230124193004.206841-3-ebiggers@kernel.org>
Date:   Tue, 24 Jan 2023 11:29:46 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Kees Cook <keescook@...omium.org>, SeongJae Park <sj@...nel.org>,
        Seth Jenkins <sethjenkins@...gle.com>,
        Jann Horn <jannh@...gle.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
        tangmeng <tangmeng@...ontech.com>,
        Luis Chamberlain <mcgrof@...nel.org>
Subject: [PATCH 5.10 02/20] kernel/panic: move panic sysctls to its own file

From: tangmeng <tangmeng@...ontech.com>

commit 9df918698408fd914493aba0b7858fef50eba63a upstream.

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.

All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the oops_all_cpu_backtrace sysctl to
its own file, kernel/panic.c.

Signed-off-by: tangmeng <tangmeng@...ontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 include/linux/kernel.h |  6 ------
 kernel/panic.c         | 26 +++++++++++++++++++++++++-
 kernel/sysctl.c        | 11 -----------
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index f5392d96d6886..084d97070ed99 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -520,12 +520,6 @@ static inline u32 int_sqrt64(u64 x)
 }
 #endif
 
-#ifdef CONFIG_SMP
-extern unsigned int sysctl_oops_all_cpu_backtrace;
-#else
-#define sysctl_oops_all_cpu_backtrace 0
-#endif /* CONFIG_SMP */
-
 extern void bust_spinlocks(int yes);
 extern int panic_timeout;
 extern unsigned long panic_print;
diff --git a/kernel/panic.c b/kernel/panic.c
index 332736a72a58e..f567195d45d9d 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -41,7 +41,9 @@
  * Should we dump all CPUs backtraces in an oops event?
  * Defaults to 0, can be changed via sysctl.
  */
-unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
+static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
+#else
+#define sysctl_oops_all_cpu_backtrace 0
 #endif /* CONFIG_SMP */
 
 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
@@ -70,6 +72,28 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
 
 EXPORT_SYMBOL(panic_notifier_list);
 
+#if defined(CONFIG_SMP) && defined(CONFIG_SYSCTL)
+static struct ctl_table kern_panic_table[] = {
+	{
+		.procname       = "oops_all_cpu_backtrace",
+		.data           = &sysctl_oops_all_cpu_backtrace,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec_minmax,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
+	},
+	{ }
+};
+
+static __init int kernel_panic_sysctls_init(void)
+{
+	register_sysctl_init("kernel", kern_panic_table);
+	return 0;
+}
+late_initcall(kernel_panic_sysctls_init);
+#endif
+
 static long no_blink(int state)
 {
 	return 0;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3eb527f8a269c..d8b7b28463135 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2199,17 +2199,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-#ifdef CONFIG_SMP
-	{
-		.procname	= "oops_all_cpu_backtrace",
-		.data		= &sysctl_oops_all_cpu_backtrace,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif /* CONFIG_SMP */
 	{
 		.procname	= "pid_max",
 		.data		= &pid_max,
-- 
2.39.1