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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 1.19 2000/12/21 15:10:16 markus Exp $"); | |
17 | ||
18 | #include "packet.h" | |
19 | #include "ssh.h" | |
20 | #include "xmalloc.h" | |
21 | #include "uidswap.h" | |
22 | #include "servconf.h" | |
23 | ||
24 | #include <openssl/rsa.h> | |
25 | #include <openssl/dsa.h> | |
26 | #include "key.h" | |
27 | #include "hostfile.h" | |
28 | ||
29 | /* | |
30 | * Tries to authenticate the user using the .rhosts file and the host using | |
31 | * its host key. Returns true if authentication succeeds. | |
32 | */ | |
33 | ||
34 | int | |
35 | auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key) | |
36 | { | |
37 | extern ServerOptions options; | |
38 | const char *canonical_hostname; | |
39 | HostStatus host_status; | |
40 | Key *client_key, *found; | |
41 | ||
42 | debug("Trying rhosts with RSA host authentication for client user %.100s", client_user); | |
43 | ||
44 | if (pw == NULL || client_host_key == NULL) | |
45 | return 0; | |
46 | ||
47 | /* Check if we would accept it using rhosts authentication. */ | |
48 | if (!auth_rhosts(pw, client_user)) | |
49 | return 0; | |
50 | ||
51 | canonical_hostname = get_canonical_hostname(); | |
52 | ||
53 | debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname); | |
54 | ||
55 | /* wrap the RSA key into a 'generic' key */ | |
56 | client_key = key_new(KEY_RSA1); | |
57 | BN_copy(client_key->rsa->e, client_host_key->e); | |
58 | BN_copy(client_key->rsa->n, client_host_key->n); | |
59 | found = key_new(KEY_RSA1); | |
60 | ||
61 | /* Check if we know the host and its host key. */ | |
62 | host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname, | |
63 | client_key, found, NULL); | |
64 | ||
65 | /* Check user host file unless ignored. */ | |
66 | if (host_status != HOST_OK && !options.ignore_user_known_hosts) { | |
67 | struct stat st; | |
68 | char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid); | |
69 | /* | |
70 | * Check file permissions of SSH_USER_HOSTFILE, auth_rsa() | |
71 | * did already check pw->pw_dir, but there is a race XXX | |
72 | */ | |
73 | if (options.strict_modes && | |
74 | (stat(user_hostfile, &st) == 0) && | |
75 | ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || | |
76 | (st.st_mode & 022) != 0)) { | |
77 | log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s", | |
78 | pw->pw_name, user_hostfile); | |
79 | } else { | |
80 | /* XXX race between stat and the following open() */ | |
81 | temporarily_use_uid(pw->pw_uid); | |
82 | host_status = check_host_in_hostfile(user_hostfile, canonical_hostname, | |
83 | client_key, found, NULL); | |
84 | restore_uid(); | |
85 | } | |
86 | xfree(user_hostfile); | |
87 | } | |
88 | key_free(client_key); | |
89 | key_free(found); | |
90 | ||
91 | if (host_status != HOST_OK) { | |
92 | debug("Rhosts with RSA host authentication denied: unknown or invalid host key"); | |
93 | packet_send_debug("Your host key cannot be verified: unknown or invalid host key."); | |
94 | return 0; | |
95 | } | |
96 | /* A matching host key was found and is known. */ | |
97 | ||
98 | /* Perform the challenge-response dialog with the client for the host key. */ | |
99 | if (!auth_rsa_challenge_dialog(client_host_key)) { | |
100 | log("Client on %.800s failed to respond correctly to host authentication.", | |
101 | canonical_hostname); | |
102 | return 0; | |
103 | } | |
104 | /* | |
105 | * We have authenticated the user using .rhosts or /etc/hosts.equiv, | |
106 | * and the host using RSA. We accept the authentication. | |
107 | */ | |
108 | ||
109 | verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.", | |
110 | pw->pw_name, client_user, canonical_hostname); | |
111 | packet_send_debug("Rhosts with RSA host authentication accepted."); | |
112 | return 1; | |
113 | } |