+20020731
+ - (bal) OpenBSD CVS Sync
+ - markus@cvs.openbsd.org 2002/07/24 16:11:18
+ [hostfile.c hostfile.h sshconnect.c]
+ print out all known keys for a host if we get a unknown host key,
+ see discussion at http://marc.theaimsgroup.com/?t=101069210100016&r=1&w=4
+
+ the ssharp mitm tool attacks users in a similar way, so i'd like to
+ pointed out again:
+ A MITM attack is always possible if the ssh client prints:
+ The authenticity of host 'bla' can't be established.
+ (protocol version 2 with pubkey authentication allows you to detect
+ MITM attacks)
+
20020730
- (bal) [uidswap.c] SCO compile correction by gert@greenie.muc.de
*/
#include "includes.h"
-RCSID("$OpenBSD: hostfile.c,v 1.29 2001/12/18 10:04:21 jakob Exp $");
+RCSID("$OpenBSD: hostfile.c,v 1.30 2002/07/24 16:11:18 markus Exp $");
#include "packet.h"
#include "match.h"
* in the list of our known hosts. Returns HOST_OK if the host is known and
* has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
* if the host is known but used to have a different host key.
+ *
+ * If no 'key' has been specified and a key of type 'keytype' is known
+ * for the specified host, then HOST_FOUND is returned.
*/
-HostStatus
-check_host_in_hostfile(const char *filename, const char *host, Key *key,
- Key *found, int *numret)
+static HostStatus
+check_host_in_hostfile_by_key_or_type(const char *filename,
+ const char *host, Key *key, int keytype, Key *found, int *numret)
{
FILE *f;
char line[8192];
HostStatus end_return;
debug3("check_host_in_hostfile: filename %s", filename);
- if (key == NULL)
- fatal("no key to look up");
+
/* Open the file containing the list of known hosts. */
f = fopen(filename, "r");
if (!f)
*/
if (!hostfile_read_key(&cp, &kbits, found))
continue;
- if (!hostfile_check_key(kbits, found, host, filename, linenum))
- continue;
if (numret != NULL)
*numret = linenum;
+ if (key == NULL) {
+ /* we found a key of the requested type */
+ if (found->type == keytype)
+ return HOST_FOUND;
+ continue;
+ }
+
+ if (!hostfile_check_key(kbits, found, host, filename, linenum))
+ continue;
+
/* Check if the current key is the same as the given key. */
if (key_equal(key, found)) {
/* Ok, they match. */
return end_return;
}
+HostStatus
+check_host_in_hostfile(const char *filename, const char *host, Key *key,
+ Key *found, int *numret)
+{
+ if (key == NULL)
+ fatal("no key to look up");
+ return (check_host_in_hostfile_by_key_or_type(filename, host, key, 0,
+ found, numret));
+}
+
+int
+lookup_key_in_hostfile_by_type(const char *filename, const char *host,
+ int keytype, Key *found, int *numret)
+{
+ return (check_host_in_hostfile_by_key_or_type(filename, host, NULL,
+ keytype, found, numret) == HOST_FOUND);
+}
+
/*
* Appends an entry to the host file. Returns false if the entry could not
* be appended.
-/* $OpenBSD: hostfile.h,v 1.10 2001/12/18 10:04:21 jakob Exp $ */
+/* $OpenBSD: hostfile.h,v 1.11 2002/07/24 16:11:18 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
#define HOSTFILE_H
typedef enum {
- HOST_OK, HOST_NEW, HOST_CHANGED
+ HOST_OK, HOST_NEW, HOST_CHANGED, HOST_FOUND,
} HostStatus;
int hostfile_read_key(char **, u_int *, Key *);
HostStatus
check_host_in_hostfile(const char *, const char *, Key *, Key *, int *);
int add_host_to_hostfile(const char *, const char *, Key *);
+int
+lookup_key_in_hostfile_by_type(const char *, const char *, int , Key *, int *);
#endif
*/
#include "includes.h"
-RCSID("$OpenBSD: sshconnect.c,v 1.131 2002/07/12 13:29:09 itojun Exp $");
+RCSID("$OpenBSD: sshconnect.c,v 1.132 2002/07/24 16:11:18 markus Exp $");
#include <openssl/bn.h>
#define INET6_ADDRSTRLEN 46
#endif
+static int show_other_keys(const char *, Key *);
+
/*
* Connect to the given ssh server using a proxy command.
*/
int salen;
char ntop[NI_MAXHOST];
char msg[1024];
- int len, host_line, ip_line;
+ int len, host_line, ip_line, has_keys;
const char *host_file = NULL, *ip_file = NULL;
/*
"have requested strict checking.", type, host);
goto fail;
} else if (options.strict_host_key_checking == 2) {
+ has_keys = show_other_keys(host, host_key);
/* The default */
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
snprintf(msg, sizeof(msg),
"The authenticity of host '%.200s (%s)' can't be "
- "established.\n"
+ "established%s\n"
"%s key fingerprint is %s.\n"
"Are you sure you want to continue connecting "
- "(yes/no)? ", host, ip, type, fp);
+ "(yes/no)? ",
+ host, ip,
+ has_keys ? ",\nbut keys of different type are already "
+ "known for this host." : ".",
+ type, fp);
xfree(fp);
if (!confirm(msg))
goto fail;
* accept the authentication.
*/
break;
+ case HOST_FOUND:
+ fatal("internal error");
+ break;
}
if (options.check_host_ip && host_status != HOST_CHANGED &&
memset(padded, 0, size);
xfree(padded);
}
+
+static int
+show_key_from_file(const char *file, const char *host, int keytype)
+{
+ Key *found;
+ char *fp;
+ int line, ret;
+
+ found = key_new(keytype);
+ if ((ret = lookup_key_in_hostfile_by_type(file, host,
+ keytype, found, &line))) {
+ fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
+ log("WARNING: %s key found for host %s\n"
+ "in file %s line %d with\n"
+ "%s key fingerprint %s.",
+ key_type(found), host, file, line,
+ key_type(found), fp);
+ xfree(fp);
+ }
+ key_free(found);
+ return (ret);
+}
+
+/* print all known host keys for a given host, but skip keys of given type */
+static int
+show_other_keys(const char *host, Key *key)
+{
+ int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
+ int i, found = 0;
+
+ for (i = 0; type[i] != -1; i++) {
+ if (type[i] == key->type)
+ continue;
+ if (type[i] != KEY_RSA1 &&
+ show_key_from_file(options.user_hostfile2, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ if (type[i] != KEY_RSA1 &&
+ show_key_from_file(options.system_hostfile2, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ if (show_key_from_file(options.user_hostfile, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ if (show_key_from_file(options.system_hostfile, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ debug2("no key of type %d for host %s", type[i], host);
+ }
+ return (found);
+}
andersk / openssh.git / commitdiff
