From ba2ec52f170a8e69d6c44238bb578f9518a7e3b7 Mon Sep 17 00:00:00 2001
From: lanzheng <lanzh...@cisco.com>
Date: Tue, 23 Feb 2021 22:49:34 -0500
Subject: [PATCH] This patch adds a kernel build config knob that disallows
changes to the sysctl variable randomize_va_space.It makes harder for
attacker to disable ASLR and reduces security risks.
Signed-off-by: lanzheng <lanzh...@cisco.com>
Reviewed-by: Yongkui Han <yon...@cisco.com>
Tested-by: Nirmala Arumugam <niaru...@cisco.com>
---
kernel/sysctl.c | 4 ++++
security/Kconfig | 8 ++++++++
2 files changed, 12 insertions(+)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c9fbdd848138..2aa9bc8044c7 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2426,7 +2426,11 @@ static struct ctl_table kern_table[] = {
.procname = "randomize_va_space",
.data = &randomize_va_space,
.maxlen = sizeof(int),
+#if defined(CONFIG_RANDOMIZE_VA_SPACE_READONLY)
+ .mode = 0444,
+#else
.mode = 0644,
+#endif
.proc_handler = proc_dointvec,
},
#endif
diff --git a/security/Kconfig b/security/Kconfig
index 7561f6f99f1d..18b9dff4648c 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -7,6 +7,14 @@ menu "Security options"
source "security/keys/Kconfig"
+config RANDOMIZE_VA_SPACE_READONLY
+ bool "Disallow change of randomize_va_space"
+ default y
+ help
+ If you say Y here, /proc/sys/kernel/randomize_va_space can not
+ be changed by any user, including root, this will help prevent
+ disablement of ASLR.
+
config SECURITY_DMESG_RESTRICT
bool "Restrict unprivileged access to the kernel syslog"
default n
--
