From 4352d9d44b935e4d000be6ec89ddb55c2bf35f24 Mon Sep 17 00:00:00 2001
From: Richard Cochran <richardcochran@gmail.com>
Date: Mon, 4 Apr 2011 08:31:23 -0700
Subject: [PATCH] ntp: fix non privileged system time shifting
The ADJ_SETOFFSET bit added in commit 094aa188 ("ntp: Add ADJ_SETOFFSET
mode bit") also introduced a way for any user to change the system time.
Sneaky or buggy calls to adjtimex() could set
ADJ_OFFSET_SS_READ | ADJ_SETOFFSET
which would result in a successful call to timekeeping_inject_offset().
This patch fixes the issue by adding the capability check.
Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/time/ntp.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 5f1bb8e2008f..f6117a4c7cb8 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -652,6 +652,8 @@ int do_adjtimex(struct timex *txc)
struct timespec delta;
delta.tv_sec = txc->time.tv_sec;
delta.tv_nsec = txc->time.tv_usec;
+ if (!capable(CAP_SYS_TIME))
+ return -EPERM;
if (!(txc->modes & ADJ_NANO))
delta.tv_nsec *= 1000;
result = timekeeping_inject_offset(&delta);
--
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