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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
4 | * All rights reserved | |
5260325f | 5 | * Rhosts or /etc/hosts.equiv authentication combined with RSA host |
6 | * authentication. | |
7 | * | |
bcbf86ec | 8 | * As far as I am concerned, the code I have written for this software |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
5260325f | 13 | */ |
8efc0c15 | 14 | |
15 | #include "includes.h" | |
42f11eb2 | 16 | RCSID("$OpenBSD: auth-rh-rsa.c,v 1.21 2001/01/21 19:05:42 markus Exp $"); |
8efc0c15 | 17 | |
18 | #include "packet.h" | |
8efc0c15 | 19 | #include "xmalloc.h" |
20 | #include "uidswap.h" | |
42f11eb2 | 21 | #include "log.h" |
b4748e2f | 22 | #include "servconf.h" |
4fe2af09 | 23 | #include "key.h" |
24 | #include "hostfile.h" | |
42f11eb2 | 25 | #include "pathnames.h" |
26 | #include "auth.h" | |
27 | #include "tildexpand.h" | |
28 | #include "canohost.h" | |
4fe2af09 | 29 | |
aa3378df | 30 | /* |
31 | * Tries to authenticate the user using the .rhosts file and the host using | |
32 | * its host key. Returns true if authentication succeeds. | |
33 | */ | |
8efc0c15 | 34 | |
6ae2364d | 35 | int |
4fe2af09 | 36 | auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key) |
8efc0c15 | 37 | { |
5260325f | 38 | extern ServerOptions options; |
39 | const char *canonical_hostname; | |
40 | HostStatus host_status; | |
4fe2af09 | 41 | Key *client_key, *found; |
5260325f | 42 | |
94ec8c6b | 43 | debug("Trying rhosts with RSA host authentication for client user %.100s", client_user); |
5260325f | 44 | |
94ec8c6b | 45 | if (pw == NULL || client_host_key == NULL) |
4fe2af09 | 46 | return 0; |
47 | ||
5260325f | 48 | /* Check if we would accept it using rhosts authentication. */ |
49 | if (!auth_rhosts(pw, client_user)) | |
50 | return 0; | |
51 | ||
52 | canonical_hostname = get_canonical_hostname(); | |
53 | ||
4fe2af09 | 54 | debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname); |
55 | ||
56 | /* wrap the RSA key into a 'generic' key */ | |
fa08c86b | 57 | client_key = key_new(KEY_RSA1); |
4fe2af09 | 58 | BN_copy(client_key->rsa->e, client_host_key->e); |
59 | BN_copy(client_key->rsa->n, client_host_key->n); | |
fa08c86b | 60 | found = key_new(KEY_RSA1); |
5260325f | 61 | |
62 | /* Check if we know the host and its host key. */ | |
42f11eb2 | 63 | host_status = check_host_in_hostfile(_PATH_SSH_SYSTEM_HOSTFILE, canonical_hostname, |
1e3b8b07 | 64 | client_key, found, NULL); |
5260325f | 65 | |
66 | /* Check user host file unless ignored. */ | |
67 | if (host_status != HOST_OK && !options.ignore_user_known_hosts) { | |
68 | struct stat st; | |
42f11eb2 | 69 | char *user_hostfile = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid); |
aa3378df | 70 | /* |
42f11eb2 | 71 | * Check file permissions of _PATH_SSH_USER_HOSTFILE, auth_rsa() |
aa3378df | 72 | * did already check pw->pw_dir, but there is a race XXX |
73 | */ | |
5260325f | 74 | if (options.strict_modes && |
75 | (stat(user_hostfile, &st) == 0) && | |
76 | ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || | |
77 | (st.st_mode & 022) != 0)) { | |
78 | log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s", | |
79 | pw->pw_name, user_hostfile); | |
80 | } else { | |
81 | /* XXX race between stat and the following open() */ | |
82 | temporarily_use_uid(pw->pw_uid); | |
83 | host_status = check_host_in_hostfile(user_hostfile, canonical_hostname, | |
1e3b8b07 | 84 | client_key, found, NULL); |
5260325f | 85 | restore_uid(); |
86 | } | |
87 | xfree(user_hostfile); | |
88 | } | |
4fe2af09 | 89 | key_free(client_key); |
90 | key_free(found); | |
5260325f | 91 | |
92 | if (host_status != HOST_OK) { | |
93 | debug("Rhosts with RSA host authentication denied: unknown or invalid host key"); | |
94 | packet_send_debug("Your host key cannot be verified: unknown or invalid host key."); | |
95 | return 0; | |
96 | } | |
97 | /* A matching host key was found and is known. */ | |
98 | ||
99 | /* Perform the challenge-response dialog with the client for the host key. */ | |
4fe2af09 | 100 | if (!auth_rsa_challenge_dialog(client_host_key)) { |
5260325f | 101 | log("Client on %.800s failed to respond correctly to host authentication.", |
102 | canonical_hostname); | |
103 | return 0; | |
104 | } | |
aa3378df | 105 | /* |
106 | * We have authenticated the user using .rhosts or /etc/hosts.equiv, | |
107 | * and the host using RSA. We accept the authentication. | |
108 | */ | |
5260325f | 109 | |
110 | verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.", | |
4fe2af09 | 111 | pw->pw_name, client_user, canonical_hostname); |
5260325f | 112 | packet_send_debug("Rhosts with RSA host authentication accepted."); |
113 | return 1; | |
8efc0c15 | 114 | } |