[PATCH 09/16] netfilter: nft_meta: use 64-bit time arithmetic

Arnd Bergmann
2019-11-08T21:36:33Z

On 32-bit architectures, get_seconds() returns an unsigned 32-bit
time value, which also matches the type used in the nft_meta
code. This will not overflow in year 2038 as a time_t would, but
it still suffers from the overflow problem later on in year 2106.

Change this instance to use the time64_t type consistently
and avoid the deprecated get_seconds().

The nft_meta_weekday() calculation potentially gets a little slower
on 32-bit architectures, but now it has the same behavior as on
64-bit architectures and does not overflow.

Fixes: 63d10e12b00d ("netfilter: nft_meta: support for time matching")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
net/netfilter/nft_meta.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index 317e3a9e8c5b..dda1e55d5801 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -33,19 +33,19 @@

static DEFINE_PER_CPU(struct rnd_state, nft_prandom_state);

-static u8 nft_meta_weekday(unsigned long secs)
+static u8 nft_meta_weekday(time64_t secs)
{
unsigned int dse;
u8 wday;

secs -= NFT_META_SECS_PER_MINUTE * sys_tz.tz_minuteswest;
- dse = secs / NFT_META_SECS_PER_DAY;
+ dse = div_u64(secs, NFT_META_SECS_PER_DAY);
wday = (4 + dse) % NFT_META_DAYS_PER_WEEK;

return wday;
}

-static u32 nft_meta_hour(unsigned long secs)
+static u32 nft_meta_hour(time64_t secs)
{
struct tm tm;

@@ -250,10 +250,10 @@ void nft_meta_get_eval(const struct nft_expr *expr,
nft_reg_store64(dest, ktime_get_real_ns());
break;
case NFT_META_TIME_DAY:
- nft_reg_store8(dest, nft_meta_weekday(get_seconds()));
+ nft_reg_store8(dest, nft_meta_weekday(ktime_get_real_seconds()));
break;
case NFT_META_TIME_HOUR:
- *dest = nft_meta_hour(get_seconds());
+ *dest = nft_meta_hour(ktime_get_real_seconds());
break;
default:
WARN_ON(1);
--
2.20.0