net: ipv4: Convert IP network timestamps to be y2038 safe

ICMP timestamp messages and IP source route options require
timestamps to be in milliseconds modulo 24 hours from
midnight UT format.

Add inet_current_timestamp() function to support this. The function
returns the required timestamp in network byte order.

Timestamp calculation is also changed to call ktime_get_real_ts64()
which uses struct timespec64. struct timespec64 is y2038 safe.
Previously it called getnstimeofday() which uses struct timespec.
struct timespec is not y2038 safe.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: James Morris <jmorris@namei.org>
Cc: Patrick McHardy <kaber@trash.net>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 8 deletions

diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index bd246792360b..4d158ff1def1 100644
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -58,10 +58,9 @@ void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
                 if (opt->ts_needaddr)
                         ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, skb, rt);
                 if (opt->ts_needtime) {
-                        struct timespec tv;
                         __be32 midtime;
-                        getnstimeofday(&tv);
-                        midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);
+
+                        midtime = inet_current_timestamp();
                         memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
                 }
                 return;
@@ -415,11 +414,10 @@ int ip_options_compile(struct net *net,
                                         break;
                                 }
                                 if (timeptr) {
-                                        struct timespec tv;
-                                        u32  midtime;
-                                        getnstimeofday(&tv);
-                                        midtime = (tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC;
-                                        put_unaligned_be32(midtime, timeptr);
+                                        __be32 midtime;
+
+                                        midtime = inet_current_timestamp();
+                                        memcpy(timeptr, &midtime, 4);
                                         opt->is_changed = 1;
                                 }
                         } else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) {