1 files changed, 93 insertions, 23 deletions

diff --git a/dh.c b/dh.c
index 4c639acc3..167d3714e 100644
--- a/dh.c
+++ b/dh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dh.c,v 1.57 2015/05/27 23:39:18 dtucker Exp $ */
+/* $OpenBSD: dh.c,v 1.60 2016/05/02 10:26:04 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  *
@@ -30,6 +30,7 @@
 #include <openssl/bn.h>
 #include <openssl/dh.h>
 
+#include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -151,10 +152,9 @@ choose_dh(int min, int wantbits, int max)
         int linenum;
         struct dhgroup dhg;
 
-        if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL &&
-            (f = fopen(_PATH_DH_PRIMES, "r")) == NULL) {
-                logit("WARNING: %s does not exist, using fixed modulus",
-                    _PATH_DH_MODULI);
+        if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL) {
+                logit("WARNING: could open open %s (%s), using fixed modulus",
+                    _PATH_DH_MODULI, strerror(errno));
                 return (dh_new_group_fallback(max));
         }
 
@@ -182,7 +182,7 @@ choose_dh(int min, int wantbits, int max)
 
         if (bestcount == 0) {
                 fclose(f);
-                logit("WARNING: no suitable primes in %s", _PATH_DH_PRIMES);
+                logit("WARNING: no suitable primes in %s", _PATH_DH_MODULI);
                 return (dh_new_group_fallback(max));
         }
 
@@ -203,7 +203,7 @@ choose_dh(int min, int wantbits, int max)
         fclose(f);
         if (linenum != which+1) {
                 logit("WARNING: line %d disappeared in %s, giving up",
-                    which, _PATH_DH_PRIMES);
+                    which, _PATH_DH_MODULI);
                 return (dh_new_group_fallback(max));
         }
 
@@ -246,12 +246,15 @@ dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
                         bits_set++;
         debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p));
 
-        /* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial */
-        if (bits_set > 1)
-                return 1;
-
-        logit("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p));
-        return 0;
+        /*
+         * if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial
+         */
+        if (bits_set < 4) {
+                logit("invalid public DH value (%d/%d)",
+                   bits_set, BN_num_bits(dh->p));
+                return 0;
+        }
+        return 1;
 }
 
 int
@@ -263,6 +266,12 @@ dh_gen_key(DH *dh, int need)
             (pbits = BN_num_bits(dh->p)) <= 0 ||
             need > INT_MAX / 2 || 2 * need > pbits)
                 return SSH_ERR_INVALID_ARGUMENT;
+        if (need < 256)
+                need = 256;
+        /*
+         * Pollard Rho, Big step/Little Step attacks are O(sqrt(n)),
+         * so double requested need here.
+         */
         dh->length = MIN(need * 2, pbits - 1);
         if (DH_generate_key(dh) == 0 ||
             !dh_pub_is_valid(dh, dh->pub_key)) {
@@ -305,6 +314,7 @@ dh_new_group(BIGNUM *gen, BIGNUM *modulus)
         return (dh);
 }
 
+/* rfc2409 "Second Oakley Group" (1024 bits) */
 DH *
 dh_new_group1(void)
 {
@@ -319,6 +329,7 @@ dh_new_group1(void)
         return (dh_new_group_asc(gen, group1));
 }
 
+/* rfc3526 group 14 "2048-bit MODP Group" */
 DH *
 dh_new_group14(void)
 {
@@ -338,12 +349,9 @@ dh_new_group14(void)
         return (dh_new_group_asc(gen, group14));
 }
 
-/*
- * 4k bit fallback group used by DH-GEX if moduli file cannot be read.
- * Source: MODP group 16 from RFC3526.
- */
+/* rfc3526 group 16 "4096-bit MODP Group" */
 DH *
-dh_new_group_fallback(int max)
+dh_new_group16(void)
 {
         static char *gen = "2", *group16 =
             "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
@@ -369,12 +377,75 @@ dh_new_group_fallback(int max)
             "93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34063199"
             "FFFFFFFF" "FFFFFFFF";
 
-        if (max < 4096) {
-                debug3("requested max size %d, using 2k bit group 14", max);
+        return (dh_new_group_asc(gen, group16));
+}
+
+/* rfc3526 group 18 "8192-bit MODP Group" */
+DH *
+dh_new_group18(void)
+{
+        static char *gen = "2", *group16 =
+            "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
+            "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
+            "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
+            "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
+            "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
+            "C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
+            "83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
+            "670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
+            "E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
+            "DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
+            "15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
+            "ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
+            "ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
+            "F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
+            "BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
+            "43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
+            "88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
+            "2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
+            "287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
+            "1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
+            "93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34028492"
+            "36C3FAB4" "D27C7026" "C1D4DCB2" "602646DE" "C9751E76" "3DBA37BD"
+            "F8FF9406" "AD9E530E" "E5DB382F" "413001AE" "B06A53ED" "9027D831"
+            "179727B0" "865A8918" "DA3EDBEB" "CF9B14ED" "44CE6CBA" "CED4BB1B"
+            "DB7F1447" "E6CC254B" "33205151" "2BD7AF42" "6FB8F401" "378CD2BF"
+            "5983CA01" "C64B92EC" "F032EA15" "D1721D03" "F482D7CE" "6E74FEF6"
+            "D55E702F" "46980C82" "B5A84031" "900B1C9E" "59E7C97F" "BEC7E8F3"
+            "23A97A7E" "36CC88BE" "0F1D45B7" "FF585AC5" "4BD407B2" "2B4154AA"
+            "CC8F6D7E" "BF48E1D8" "14CC5ED2" "0F8037E0" "A79715EE" "F29BE328"
+            "06A1D58B" "B7C5DA76" "F550AA3D" "8A1FBFF0" "EB19CCB1" "A313D55C"
+            "DA56C9EC" "2EF29632" "387FE8D7" "6E3C0468" "043E8F66" "3F4860EE"
+            "12BF2D5B" "0B7474D6" "E694F91E" "6DBE1159" "74A3926F" "12FEE5E4"
+            "38777CB6" "A932DF8C" "D8BEC4D0" "73B931BA" "3BC832B6" "8D9DD300"
+            "741FA7BF" "8AFC47ED" "2576F693" "6BA42466" "3AAB639C" "5AE4F568"
+            "3423B474" "2BF1C978" "238F16CB" "E39D652D" "E3FDB8BE" "FC848AD9"
+            "22222E04" "A4037C07" "13EB57A8" "1A23F0C7" "3473FC64" "6CEA306B"
+            "4BCBC886" "2F8385DD" "FA9D4B7F" "A2C087E8" "79683303" "ED5BDD3A"
+            "062B3CF5" "B3A278A6" "6D2A13F8" "3F44F82D" "DF310EE0" "74AB6A36"
+            "4597E899" "A0255DC1" "64F31CC5" "0846851D" "F9AB4819" "5DED7EA1"
+            "B1D510BD" "7EE74D73" "FAF36BC3" "1ECFA268" "359046F4" "EB879F92"
+            "4009438B" "481C6CD7" "889A002E" "D5EE382B" "C9190DA6" "FC026E47"
+            "9558E447" "5677E9AA" "9E3050E2" "765694DF" "C81F56E8" "80B96E71"
+            "60C980DD" "98EDD3DF" "FFFFFFFF" "FFFFFFFF";
+
+        return (dh_new_group_asc(gen, group16));
+}
+
+/* Select fallback group used by DH-GEX if moduli file cannot be read. */
+DH *
+dh_new_group_fallback(int max)
+{
+        debug3("%s: requested max size %d", __func__, max);
+        if (max < 3072) {
+                debug3("using 2k bit group 14");
                 return dh_new_group14();
+        } else if (max < 6144) {
+                debug3("using 4k bit group 16");
+                return dh_new_group16();
         }
-        debug3("using 4k bit group 16");
-        return (dh_new_group_asc(gen, group16));
+        debug3("using 8k bit group 18");
+        return dh_new_group18();
 }
 
 /*
@@ -384,7 +455,6 @@ dh_new_group_fallback(int max)
  * Management Part 1 (rev 3) limited by the recommended maximum value
  * from RFC4419 section 3.
  */
-
 u_int
 dh_estimate(int bits)
 {