Annotation of src/usr.bin/ssh/hostfile.c, Revision 1.18.2.3
1.1 deraadt 1: /*
1.8 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Functions for manipulating the known hosts files.
1.16 markus 6: *
1.18.2.3! jason 7: * As far as I am concerned, the code I have written for this software
! 8: * can be used freely for any purpose. Any derived versions of this
! 9: * software must be clearly marked as such, and if the derived work is
! 10: * incompatible with the protocol description in the RFC file, it must be
! 11: * called by a name other than "ssh" or "Secure Shell".
! 12: *
! 13: *
! 14: * Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
! 15: * Copyright (c) 1999 Niels Provos. All rights reserved.
! 16: *
! 17: * Redistribution and use in source and binary forms, with or without
! 18: * modification, are permitted provided that the following conditions
! 19: * are met:
! 20: * 1. Redistributions of source code must retain the above copyright
! 21: * notice, this list of conditions and the following disclaimer.
! 22: * 2. Redistributions in binary form must reproduce the above copyright
! 23: * notice, this list of conditions and the following disclaimer in the
! 24: * documentation and/or other materials provided with the distribution.
! 25: *
! 26: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
! 27: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
! 28: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
! 29: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
! 30: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
! 31: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
! 32: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
! 33: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
! 34: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
! 35: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.8 deraadt 36: */
1.1 deraadt 37:
38: #include "includes.h"
1.18.2.3! jason 39: RCSID("$OpenBSD: hostfile.c,v 1.20 2000/09/07 20:27:51 deraadt Exp $");
1.1 deraadt 40:
41: #include "packet.h"
1.14 markus 42: #include "match.h"
1.1 deraadt 43: #include "ssh.h"
1.15 markus 44: #include <openssl/rsa.h>
45: #include <openssl/dsa.h>
1.14 markus 46: #include "key.h"
47: #include "hostfile.h"
1.1 deraadt 48:
1.9 markus 49: /*
1.14 markus 50: * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
51: * pointer over the key. Skips any whitespace at the beginning and at end.
1.9 markus 52: */
1.1 deraadt 53:
1.2 provos 54: int
1.14 markus 55: hostfile_read_key(char **cpp, unsigned int *bitsp, Key *ret)
1.1 deraadt 56: {
1.7 markus 57: unsigned int bits;
58: char *cp;
59:
60: /* Skip leading whitespace. */
1.9 markus 61: for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
62: ;
1.1 deraadt 63:
1.17 markus 64: bits = key_read(ret, &cp);
65: if (bits == 0)
1.7 markus 66: return 0;
67:
68: /* Skip trailing whitespace. */
1.9 markus 69: for (; *cp == ' ' || *cp == '\t'; cp++)
70: ;
1.7 markus 71:
72: /* Return results. */
73: *cpp = cp;
74: *bitsp = bits;
75: return 1;
1.1 deraadt 76: }
77:
1.14 markus 78: int
79: auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n)
80: {
81: Key *k = key_new(KEY_RSA);
82: int ret = hostfile_read_key(cpp, bitsp, k);
83: BN_copy(e, k->rsa->e);
84: BN_copy(n, k->rsa->n);
85: key_free(k);
86: return ret;
87: }
1.1 deraadt 88:
1.2 provos 89: int
1.14 markus 90: hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
1.1 deraadt 91: {
1.14 markus 92: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL)
93: return 1;
94: if (bits != BN_num_bits(key->rsa->n)) {
1.18 markus 95: log("Warning: %s, line %d: keysize mismatch for host %s: "
1.14 markus 96: "actual %d vs. announced %d.",
97: filename, linenum, host, BN_num_bits(key->rsa->n), bits);
1.18 markus 98: log("Warning: replace %d with %d in %s, line %d.",
1.14 markus 99: bits, BN_num_bits(key->rsa->n), filename, linenum);
1.1 deraadt 100: }
1.14 markus 101: return 1;
1.1 deraadt 102: }
103:
1.9 markus 104: /*
105: * Checks whether the given host (which must be in all lowercase) is already
106: * in the list of our known hosts. Returns HOST_OK if the host is known and
107: * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
108: * if the host is known but used to have a different host key.
109: */
1.1 deraadt 110:
1.2 provos 111: HostStatus
1.14 markus 112: check_host_in_hostfile(const char *filename, const char *host, Key *key, Key *found)
1.1 deraadt 113: {
1.7 markus 114: FILE *f;
115: char line[8192];
116: int linenum = 0;
1.12 markus 117: unsigned int kbits, hostlen;
1.7 markus 118: char *cp, *cp2;
119: HostStatus end_return;
120:
1.14 markus 121: if (key == NULL)
122: fatal("no key to look up");
1.7 markus 123: /* Open the file containing the list of known hosts. */
124: f = fopen(filename, "r");
125: if (!f)
126: return HOST_NEW;
127:
128: /* Cache the length of the host name. */
129: hostlen = strlen(host);
130:
1.9 markus 131: /*
132: * Return value when the loop terminates. This is set to
133: * HOST_CHANGED if we have seen a different key for the host and have
134: * not found the proper one.
135: */
1.7 markus 136: end_return = HOST_NEW;
137:
138: /* Go trough the file. */
139: while (fgets(line, sizeof(line), f)) {
140: cp = line;
141: linenum++;
142:
1.9 markus 143: /* Skip any leading whitespace, comments and empty lines. */
144: for (; *cp == ' ' || *cp == '\t'; cp++)
145: ;
1.7 markus 146: if (!*cp || *cp == '#' || *cp == '\n')
147: continue;
148:
149: /* Find the end of the host name portion. */
1.9 markus 150: for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
151: ;
1.7 markus 152:
153: /* Check if the host name matches. */
1.18.2.1 jason 154: if (match_hostname(host, cp, (unsigned int) (cp2 - cp)) != 1)
1.7 markus 155: continue;
156:
157: /* Got a match. Skip host name. */
158: cp = cp2;
159:
1.9 markus 160: /*
161: * Extract the key from the line. This will skip any leading
162: * whitespace. Ignore badly formatted lines.
163: */
1.14 markus 164: if (!hostfile_read_key(&cp, &kbits, found))
165: continue;
166: if (!hostfile_check_key(kbits, found, host, filename, linenum))
1.7 markus 167: continue;
168:
169: /* Check if the current key is the same as the given key. */
1.14 markus 170: if (key_equal(key, found)) {
1.7 markus 171: /* Ok, they match. */
172: fclose(f);
173: return HOST_OK;
174: }
1.9 markus 175: /*
176: * They do not match. We will continue to go through the
177: * file; however, we note that we will not return that it is
178: * new.
179: */
1.7 markus 180: end_return = HOST_CHANGED;
1.1 deraadt 181: }
1.7 markus 182: /* Clear variables and close the file. */
183: fclose(f);
184:
1.9 markus 185: /*
186: * Return either HOST_NEW or HOST_CHANGED, depending on whether we
187: * saw a different key for the host.
188: */
1.7 markus 189: return end_return;
1.1 deraadt 190: }
191:
1.9 markus 192: /*
193: * Appends an entry to the host file. Returns false if the entry could not
194: * be appended.
195: */
1.1 deraadt 196:
1.2 provos 197: int
1.14 markus 198: add_host_to_hostfile(const char *filename, const char *host, Key *key)
1.1 deraadt 199: {
1.7 markus 200: FILE *f;
1.14 markus 201: int success = 0;
202: if (key == NULL)
1.17 markus 203: return 1; /* XXX ? */
1.7 markus 204: f = fopen(filename, "a");
205: if (!f)
206: return 0;
1.14 markus 207: fprintf(f, "%s ", host);
208: if (key_write(key, f)) {
209: success = 1;
210: } else {
1.17 markus 211: error("add_host_to_hostfile: saving key in %s failed", filename);
1.7 markus 212: }
1.17 markus 213: fprintf(f, "\n");
1.7 markus 214: fclose(f);
1.14 markus 215: return success;
1.1 deraadt 216: }
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