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1 | /* | |
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 | * Rhosts or /etc/hosts.equiv authentication combined with RSA host | |
6 | * authentication. | |
7 | * | |
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". | |
13 | */ | |
14 | ||
15 | #include "includes.h" | |
16 | RCSID("$OpenBSD: auth-rh-rsa.c,v 1.22 2001/02/03 10:08:36 markus Exp $"); | |
17 | ||
18 | #include "packet.h" | |
19 | #include "xmalloc.h" | |
20 | #include "uidswap.h" | |
21 | #include "log.h" | |
22 | #include "servconf.h" | |
23 | #include "key.h" | |
24 | #include "hostfile.h" | |
25 | #include "pathnames.h" | |
26 | #include "auth.h" | |
27 | #include "tildexpand.h" | |
28 | #include "canohost.h" | |
29 | ||
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 | */ | |
34 | ||
35 | int | |
36 | auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key) | |
37 | { | |
38 | extern ServerOptions options; | |
39 | const char *canonical_hostname; | |
40 | HostStatus host_status; | |
41 | Key *client_key, *found; | |
42 | ||
43 | debug("Trying rhosts with RSA host authentication for client user %.100s", client_user); | |
44 | ||
45 | if (pw == NULL || client_host_key == NULL) | |
46 | return 0; | |
47 | ||
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 | options.reverse_mapping_check); | |
54 | ||
55 | debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname); | |
56 | ||
57 | /* wrap the RSA key into a 'generic' key */ | |
58 | client_key = key_new(KEY_RSA1); | |
59 | BN_copy(client_key->rsa->e, client_host_key->e); | |
60 | BN_copy(client_key->rsa->n, client_host_key->n); | |
61 | found = key_new(KEY_RSA1); | |
62 | ||
63 | /* Check if we know the host and its host key. */ | |
64 | host_status = check_host_in_hostfile(_PATH_SSH_SYSTEM_HOSTFILE, canonical_hostname, | |
65 | client_key, found, NULL); | |
66 | ||
67 | /* Check user host file unless ignored. */ | |
68 | if (host_status != HOST_OK && !options.ignore_user_known_hosts) { | |
69 | struct stat st; | |
70 | char *user_hostfile = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid); | |
71 | /* | |
72 | * Check file permissions of _PATH_SSH_USER_HOSTFILE, auth_rsa() | |
73 | * did already check pw->pw_dir, but there is a race XXX | |
74 | */ | |
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, | |
85 | client_key, found, NULL); | |
86 | restore_uid(); | |
87 | } | |
88 | xfree(user_hostfile); | |
89 | } | |
90 | key_free(client_key); | |
91 | key_free(found); | |
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. */ | |
101 | if (!auth_rsa_challenge_dialog(client_host_key)) { | |
102 | log("Client on %.800s failed to respond correctly to host authentication.", | |
103 | canonical_hostname); | |
104 | return 0; | |
105 | } | |
106 | /* | |
107 | * We have authenticated the user using .rhosts or /etc/hosts.equiv, | |
108 | * and the host using RSA. We accept the authentication. | |
109 | */ | |
110 | ||
111 | verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.", | |
112 | pw->pw_name, client_user, canonical_hostname); | |
113 | packet_send_debug("Rhosts with RSA host authentication accepted."); | |
114 | return 1; | |
115 | } |