port src/sbin/ping/ping.c r1.119 and r1.121 to ping6:

> add a mac to the timestamp payload and calculate it with siphash.
>
> this lets us have some confidence that the timestamp hasnt been
> damaged or tampered with in transit.
>
> discussed with jp aumasson
> ok florian@

diff --git a/sbin/ping6/ping6.c b/sbin/ping6/ping6.c
index 87bd9e1..a5d8c3c 100644 (file)
--- a/sbin/ping6/ping6.c
+++ b/sbin/ping6/ping6.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: ping6.c,v 1.105 2015/03/23 10:36:24 dlg Exp $ */
+/*     $OpenBSD: ping6.c,v 1.106 2015/04/20 00:46:32 dlg Exp $ */
 /*     $KAME: ping6.c,v 1.163 2002/10/25 02:19:06 itojun Exp $ */
 
 /*
@@ -109,16 +109,22 @@
 #include <poll.h>
 
 #include <md5.h>
+#include <siphash.h>
 
 struct tv64 {
        u_int64_t tv64_sec;
        u_int64_t tv64_nsec;
 };
 
+struct payload {
+       struct tv64     tv64;
+       u_int8_t        mac[SIPHASH_DIGEST_LENGTH];
+};
+
 #define MAXPACKETLEN   131072
 #define        IP6LEN          40
 #define ICMP6ECHOLEN   8       /* icmp echo header len excluding time */
-#define ICMP6ECHOTMLEN sizeof(struct tv64)
+#define ICMP6ECHOTMLEN sizeof(struct payload)
 #define ICMP6_NIQLEN   (ICMP6ECHOLEN + 8)
 /* FQDN case, 64 bits of nonce + 32 bits ttl */
 #define ICMP6_NIRLEN   (ICMP6ECHOLEN + 12)
@@ -198,6 +204,7 @@ double tmax = 0.0;          /* maximum round trip time */
 double tsum = 0.0;             /* sum of all times, for doing average */
 double tsumsq = 0.0;           /* sum of all times squared, for std. dev. */
 struct tv64 tv64_offset;       /* random offset for time values */
+SIPHASH_KEY mac_key;
 
 /* for node addresses */
 u_short naflags;
@@ -578,7 +585,7 @@ main(int argc, char *argv[])
 
 
        if ((options & F_NOUSERDATA) == 0) {
-               if (datalen >= sizeof(struct tv64)) {
+               if (datalen >= sizeof(struct payload)) {
                        /* we can time transfer */
                        timing = 1;
                } else
@@ -805,6 +812,7 @@ main(int argc, char *argv[])
                warn("setsockopt(IPV6_RECVHOPLIMIT)"); /* XXX err? */
 
        arc4random_buf(&tv64_offset, sizeof(tv64_offset));
+       arc4random_buf(&mac_key, sizeof(mac_key));
 
        printf("PING6(%lu=40+8+%lu bytes) ", (unsigned long)(40 + pingerlen()),
            (unsigned long)(pingerlen() - 8));
@@ -1074,16 +1082,27 @@ pinger(void)
                icp->icmp6_id = htons(ident);
                icp->icmp6_seq = ntohs(seq);
                if (timing) {
+                       SIPHASH_CTX ctx;
                        struct timespec ts;
-                       struct tv64 tv64;
+                       struct payload payload;
+                       struct tv64 *tv64 = &payload.tv64;
 
                        if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
                                err(1, "clock_gettime(CLOCK_MONOTONIC)");
-                       tv64.tv64_sec = htobe64((u_int64_t)ts.tv_sec +
+                       tv64->tv64_sec = htobe64((u_int64_t)ts.tv_sec +
                            tv64_offset.tv64_sec);
-                       tv64.tv64_nsec = htobe64((u_int64_t)ts.tv_nsec +
+                       tv64->tv64_nsec = htobe64((u_int64_t)ts.tv_nsec +
                            tv64_offset.tv64_nsec);
-                       memcpy(&outpack[ICMP6ECHOLEN], &tv64, sizeof(tv64));
+
+                       SipHash24_Init(&ctx, &mac_key);
+                       SipHash24_Update(&ctx, tv64, sizeof(*tv64));
+                       SipHash24_Update(&ctx, &ident, sizeof(ident));
+                       SipHash24_Update(&ctx,
+                           &icp->icmp6_seq, sizeof(icp->icmp6_seq));
+                       SipHash24_Final(&payload.mac, &ctx);
+
+                       memcpy(&outpack[ICMP6ECHOLEN],
+                           &payload, sizeof(payload));
                }
                cc = ICMP6ECHOLEN + datalen;
        }
@@ -1212,7 +1231,8 @@ pr_pack(u_char *buf, int cc, struct msghdr *mhdr)
        u_char *cp = NULL, *dp, *end = buf + cc;
        struct in6_pktinfo *pktinfo = NULL;
        struct timespec ts, tp;
-       struct tv64 tv64;
+       struct payload payload;
+       struct tv64 *tv64;
        double triptime = 0;
        int dupflag;
        size_t off;
@@ -1255,10 +1275,28 @@ pr_pack(u_char *buf, int cc, struct msghdr *mhdr)
                seq = ntohs(icp->icmp6_seq);
                ++nreceived;
                if (timing) {
-                       memcpy(&tv64, icp + 1, sizeof(tv64));
-                       tp.tv_sec = betoh64(tv64.tv64_sec) -
+                       SIPHASH_CTX ctx;
+                       u_int8_t mac[SIPHASH_DIGEST_LENGTH];
+
+                       memcpy(&payload, icp + 1, sizeof(payload));
+                       tv64 = &payload.tv64;
+
+                       SipHash24_Init(&ctx, &mac_key);
+                       SipHash24_Update(&ctx, tv64, sizeof(*tv64));
+                       SipHash24_Update(&ctx, &ident, sizeof(ident));
+                       SipHash24_Update(&ctx,
+                           &icp->icmp6_seq, sizeof(icp->icmp6_seq));
+                       SipHash24_Final(mac, &ctx);
+
+                       if (timingsafe_memcmp(mac, &payload.mac,
+                           sizeof(mac)) != 0) {
+                               (void)printf("signature mismatch!\n");
+                               return;
+                       }
+
+                       tp.tv_sec = betoh64(tv64->tv64_sec) -
                            tv64_offset.tv64_sec;
-                       tp.tv_nsec = betoh64(tv64.tv64_nsec) -
+                       tp.tv_nsec = betoh64(tv64->tv64_nsec) -
                            tv64_offset.tv64_nsec;
                        timespecsub(&ts, &tp, &ts);
                        triptime = ((double)ts.tv_sec) * 1000.0 +
@@ -2328,7 +2366,7 @@ fill(char *bp, char *patp)
 /* xxx */
        if (ii > 0)
                for (kk = 0;
-                   kk <= MAXDATALEN - (8 + sizeof(struct tv64) + ii);
+                   kk <= MAXDATALEN - (8 + sizeof(struct payload) + ii);
                    kk += ii)
                        for (jj = 0; jj < ii; ++jj)
                                bp[jj + kk] = pat[jj];