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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" | |
61e96248 | 16 | RCSID("$OpenBSD: auth-rh-rsa.c,v 1.22 2001/02/03 10:08:36 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 | ||
61e96248 | 52 | canonical_hostname = get_canonical_hostname( |
53 | options.reverse_mapping_check); | |
5260325f | 54 | |
4fe2af09 | 55 | debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname); |
56 | ||
57 | /* wrap the RSA key into a 'generic' key */ | |
fa08c86b | 58 | client_key = key_new(KEY_RSA1); |
4fe2af09 | 59 | BN_copy(client_key->rsa->e, client_host_key->e); |
60 | BN_copy(client_key->rsa->n, client_host_key->n); | |
fa08c86b | 61 | found = key_new(KEY_RSA1); |
5260325f | 62 | |
63 | /* Check if we know the host and its host key. */ | |
42f11eb2 | 64 | host_status = check_host_in_hostfile(_PATH_SSH_SYSTEM_HOSTFILE, canonical_hostname, |
1e3b8b07 | 65 | client_key, found, NULL); |
5260325f | 66 | |
67 | /* Check user host file unless ignored. */ | |
68 | if (host_status != HOST_OK && !options.ignore_user_known_hosts) { | |
69 | struct stat st; | |
42f11eb2 | 70 | char *user_hostfile = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid); |
aa3378df | 71 | /* |
42f11eb2 | 72 | * Check file permissions of _PATH_SSH_USER_HOSTFILE, auth_rsa() |
aa3378df | 73 | * did already check pw->pw_dir, but there is a race XXX |
74 | */ | |
5260325f | 75 | if (options.strict_modes && |
76 | (stat(user_hostfile, &st) == 0) && | |
77 | ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || | |
78 | (st.st_mode & 022) != 0)) { | |
79 | log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s", | |
80 | pw->pw_name, user_hostfile); | |
81 | } else { | |
82 | /* XXX race between stat and the following open() */ | |
83 | temporarily_use_uid(pw->pw_uid); | |
84 | host_status = check_host_in_hostfile(user_hostfile, canonical_hostname, | |
1e3b8b07 | 85 | client_key, found, NULL); |
5260325f | 86 | restore_uid(); |
87 | } | |
88 | xfree(user_hostfile); | |
89 | } | |
4fe2af09 | 90 | key_free(client_key); |
91 | key_free(found); | |
5260325f | 92 | |
93 | if (host_status != HOST_OK) { | |
94 | debug("Rhosts with RSA host authentication denied: unknown or invalid host key"); | |
95 | packet_send_debug("Your host key cannot be verified: unknown or invalid host key."); | |
96 | return 0; | |
97 | } | |
98 | /* A matching host key was found and is known. */ | |
99 | ||
100 | /* Perform the challenge-response dialog with the client for the host key. */ | |
4fe2af09 | 101 | if (!auth_rsa_challenge_dialog(client_host_key)) { |
5260325f | 102 | log("Client on %.800s failed to respond correctly to host authentication.", |
103 | canonical_hostname); | |
104 | return 0; | |
105 | } | |
aa3378df | 106 | /* |
107 | * We have authenticated the user using .rhosts or /etc/hosts.equiv, | |
108 | * and the host using RSA. We accept the authentication. | |
109 | */ | |
5260325f | 110 | |
111 | verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.", | |
4fe2af09 | 112 | pw->pw_name, client_user, canonical_hostname); |
5260325f | 113 | packet_send_debug("Rhosts with RSA host authentication accepted."); |
114 | return 1; | |
8efc0c15 | 115 | } |