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authorRichard Cochran <richardcochran@gmail.com>2011-04-04 08:31:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-04-04 08:31:23 -0700
commit4352d9d44b935e4d000be6ec89ddb55c2bf35f24 (patch)
tree26b9d37f5a41b4c01d800a444ad230eafb48e47a
parentb3b896c73b4b04b506816a09994192e3a54f0fef (diff)
downloadlinux-4352d9d44b935e4d000be6ec89ddb55c2bf35f24.tar.bz2
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>
-rw-r--r--kernel/time/ntp.c2
1 files changed, 2 insertions, 0 deletions
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);