Annotation of src/usr.bin/ssh/dh.c, Revision 1.9
1.1 provos 1: /*
2: * Copyright (c) 2000 Niels Provos. All rights reserved.
3: *
4: * Redistribution and use in source and binary forms, with or without
5: * modification, are permitted provided that the following conditions
6: * are met:
7: * 1. Redistributions of source code must retain the above copyright
8: * notice, this list of conditions and the following disclaimer.
9: * 2. Redistributions in binary form must reproduce the above copyright
10: * notice, this list of conditions and the following disclaimer in the
11: * documentation and/or other materials provided with the distribution.
12: *
13: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: */
24:
25: #include "includes.h"
1.9 ! provos 26: RCSID("$OpenBSD: dh.c,v 1.8 2001/03/05 17:58:22 stevesk Exp $");
1.1 provos 27:
28: #include "xmalloc.h"
29:
30: #include <openssl/bn.h>
31: #include <openssl/dh.h>
32: #include <openssl/evp.h>
33:
34: #include "buffer.h"
1.6 markus 35: #include "cipher.h"
1.1 provos 36: #include "kex.h"
37: #include "dh.h"
1.5 markus 38: #include "pathnames.h"
1.6 markus 39: #include "log.h"
40: #include "misc.h"
1.1 provos 41:
42: int
43: parse_prime(int linenum, char *line, struct dhgroup *dhg)
44: {
45: char *cp, *arg;
46: char *strsize, *gen, *prime;
47:
48: cp = line;
49: arg = strdelim(&cp);
50: /* Ignore leading whitespace */
51: if (*arg == '\0')
52: arg = strdelim(&cp);
53: if (!*arg || *arg == '#')
54: return 0;
55:
56: /* time */
57: if (cp == NULL || *arg == '\0')
58: goto fail;
59: arg = strsep(&cp, " "); /* type */
60: if (cp == NULL || *arg == '\0')
61: goto fail;
62: arg = strsep(&cp, " "); /* tests */
63: if (cp == NULL || *arg == '\0')
64: goto fail;
65: arg = strsep(&cp, " "); /* tries */
66: if (cp == NULL || *arg == '\0')
67: goto fail;
68: strsize = strsep(&cp, " "); /* size */
69: if (cp == NULL || *strsize == '\0' ||
70: (dhg->size = atoi(strsize)) == 0)
71: goto fail;
1.9 ! provos 72: /* The whole group is one bit larger */
! 73: dhg->size++;
1.1 provos 74: gen = strsep(&cp, " "); /* gen */
75: if (cp == NULL || *gen == '\0')
76: goto fail;
77: prime = strsep(&cp, " "); /* prime */
78: if (cp != NULL || *prime == '\0')
79: goto fail;
80:
81: dhg->g = BN_new();
82: if (BN_hex2bn(&dhg->g, gen) < 0) {
83: BN_free(dhg->g);
84: goto fail;
85: }
86: dhg->p = BN_new();
87: if (BN_hex2bn(&dhg->p, prime) < 0) {
88: BN_free(dhg->g);
89: BN_free(dhg->p);
90: goto fail;
91: }
92:
93: return (1);
94: fail:
1.7 millert 95: error("Bad prime description in line %d", linenum);
1.1 provos 96: return (0);
97: }
98:
99: DH *
1.9 ! provos 100: choose_dh(int min, int wantbits, int max)
1.1 provos 101: {
102: FILE *f;
103: char line[1024];
104: int best, bestcount, which;
105: int linenum;
106: struct dhgroup dhg;
107:
1.5 markus 108: f = fopen(_PATH_DH_PRIMES, "r");
1.1 provos 109: if (!f) {
1.5 markus 110: log("WARNING: %s does not exist, using old prime", _PATH_DH_PRIMES);
1.1 provos 111: return (dh_new_group1());
112: }
113:
114: linenum = 0;
115: best = bestcount = 0;
116: while (fgets(line, sizeof(line), f)) {
117: linenum++;
118: if (!parse_prime(linenum, line, &dhg))
119: continue;
120: BN_free(dhg.g);
121: BN_free(dhg.p);
122:
1.9 ! provos 123: if (dhg.size > max || dhg.size < min)
! 124: continue;
! 125:
! 126: if ((dhg.size > wantbits && dhg.size < best) ||
! 127: (dhg.size > best && best < wantbits)) {
1.1 provos 128: best = dhg.size;
129: bestcount = 0;
130: }
131: if (dhg.size == best)
132: bestcount++;
133: }
134: fclose (f);
135:
136: if (bestcount == 0) {
1.9 ! provos 137: log("WARNING: no suitable primes in %s", _PATH_DH_PRIMES);
! 138: return (NULL);
1.1 provos 139: }
140:
1.5 markus 141: f = fopen(_PATH_DH_PRIMES, "r");
1.1 provos 142: if (!f) {
1.8 stevesk 143: fatal("WARNING: %s disappeared, giving up", _PATH_DH_PRIMES);
1.1 provos 144: }
145:
146: linenum = 0;
147: which = arc4random() % bestcount;
148: while (fgets(line, sizeof(line), f)) {
149: if (!parse_prime(linenum, line, &dhg))
1.9 ! provos 150: continue;
! 151: if (dhg.size > max || dhg.size < min)
1.1 provos 152: continue;
153: if (dhg.size != best)
154: continue;
155: if (linenum++ != which) {
156: BN_free(dhg.g);
157: BN_free(dhg.p);
158: continue;
159: }
160: break;
161: }
162: fclose(f);
163:
164: return (dh_new_group(dhg.g, dhg.p));
165: }
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