[patch 66/76] NETFILTER: xt_time: fix failure to match on Sundays

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To: <linux-kernel@...>, <stable@...>
Cc: Justin Forbes <jmforbes@...>, Zwane Mwaikambo <zwane@...>, Theodore Ts'o <tytso@...>, Randy Dunlap <rdunlap@...>, Dave Jones <davej@...>, Chuck Wolber <chuckw@...>, Chris Wedgwood <reviews@...>, Michael Krufky <mkrufky@...>, Chuck Ebbert <cebbert@...>, Domenico Andreoli <cavokz@...>, <torvalds@...>, <akpm@...>, <alan@...>, Patrick McHardy <kaber@...>, <netfilter-devel@...>, <davem@...>, Jan Engelhardt <jengelh@...>, Greg Kroah-Hartman <gregkh@...>
Date: Friday, March 21, 2008 - 6:43 pm

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Jan Engelhardt <jengelh@computergmbh.de>

Upstream commit 4f4c9430:

xt_time_match() in net/netfilter/xt_time.c in kernel 2.6.24 never
matches on Sundays. On my host I have a rule like

iptables -A OUTPUT -m time --weekdays Sun -j REJECT

and it never matches. The problem is in localtime_2(), which uses

    r->weekday = (4 + r->dse) % 7;

to map the epoch day onto a weekday in {0,...,6}. In particular this
gives 0 for Sundays. But 0 has to be wrong; a weekday of 0 can never
match. xt_time_match() has

    if (!(info->weekdays_match & (1 << current_time.weekday)))
        return false;

and when current_time.weekday = 0, the result of the & is always
zero, even when info->weekdays_match = XT_TIME_ALL_WEEKDAYS = 0xFE.

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

 net/netfilter/xt_time.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/netfilter/xt_time.c
+++ b/net/netfilter/xt_time.c
@@ -95,8 +95,11 @@ static inline void localtime_2(struct xt
 	 */
 	r->dse = time / 86400;
 
-	/* 1970-01-01 (w=0) was a Thursday (4). */
-	r->weekday = (4 + r->dse) % 7;
+	/*
+	 * 1970-01-01 (w=0) was a Thursday (4).
+	 * -1 and +1 map Sunday properly onto 7.
+	 */
+	r->weekday = (4 + r->dse - 1) % 7 + 1;
 }
 
 static void localtime_3(struct xtm *r, time_t time)

-- 
--
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[patch 66/76] NETFILTER: xt_time: fix failure to match on Su..., Chris Wright, (Fri Mar 21, 6:43 pm)