linux-kernel - [PATCH] power: disable hibernation if module loading is disabled

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Message-Id: <1299255084-4390-1-git-send-email-segoon@openwall.com>
Date:	Fri,  4 Mar 2011 19:11:24 +0300
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	linux-kernel@...r.kernel.org
Cc:	security@...nel.org, Len Brown <len.brown@...el.com>,
	Pavel Machek <pavel@....cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
	linux-pm@...ts.linux-foundation.org
Subject: [PATCH] power: disable hibernation if module loading is disabled

If /proc/sys/kernel/modules_disabled is set to 1, then nobody (even full
root) may not read/write arbitrary kernel memory.  In spite of it,
hibernation allows anyone with an access to either /dev/snapshot or
/sys/power/ make the full snapshot of the system.  This snapshot may be
freely changed and uploaded back.

Signed-off-by: Vasiliy Kulikov <segoon@...nwall.com>
---
 kernel/power/hibernate.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 1832bd2..1ac9eee 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -328,6 +328,9 @@ int hibernation_snapshot(int platform_mode)
 {
 	int error;
 
+	if (modules_disabled)
+		return -EPERM;
+
 	error = platform_begin(platform_mode);
 	if (error)
 		goto Close;
@@ -385,6 +388,9 @@ static int resume_target_kernel(bool platform_mode)
 {
 	int error;
 
+	if (modules_disabled)
+		return -EPERM;
+
 	error = dpm_suspend_noirq(PMSG_QUIESCE);
 	if (error) {
 		printk(KERN_ERR "PM: Some devices failed to power down, "
-- 
1.7.0.4

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