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Commit 4352d9d4 authored by Richard Cochran's avatar Richard Cochran Committed by Linus Torvalds
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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: default avatarRichard Cochran <richard.cochran@omicron.at>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b3b896c7

kernel/time/ntp.c

+2 −0
Original line number Diff line number Diff line
@@ -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);