NETFILTER: xt_time: fix failure to match on Sundays

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>

diff --git a/net/netfilter/xt_time.c b/net/netfilter/xt_time.c
index f9c55dcd894b70e9cef74203a27f2d747d4f2d8e..5222a97c6749ce20e9b247b88f4d39c96b1ae3b5 100644 (file)
--- a/net/netfilter/xt_time.c
+++ b/net/netfilter/xt_time.c
@@ -95,8 +95,11 @@ static inline void localtime_2(struct xtm *r, time_t time)
         */
        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)