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8efc0c15 | 1 | /* |
2 | ||
3 | auth-rh-rsa.c | |
4 | ||
5 | Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | ||
7 | Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
8 | All rights reserved | |
9 | ||
10 | Created: Sun May 7 03:08:06 1995 ylo | |
11 | ||
12 | Rhosts or /etc/hosts.equiv authentication combined with RSA host | |
13 | authentication. | |
14 | ||
15 | */ | |
16 | ||
17 | #include "includes.h" | |
18 | RCSID("$Id$"); | |
19 | ||
20 | #include "packet.h" | |
21 | #include "ssh.h" | |
22 | #include "xmalloc.h" | |
23 | #include "uidswap.h" | |
b4748e2f | 24 | #include "servconf.h" |
8efc0c15 | 25 | |
26 | /* Tries to authenticate the user using the .rhosts file and the host using | |
b4748e2f | 27 | its host key. Returns true if authentication succeeds. */ |
8efc0c15 | 28 | |
29 | int auth_rhosts_rsa(struct passwd *pw, const char *client_user, | |
b4748e2f | 30 | BIGNUM *client_host_key_e, BIGNUM *client_host_key_n) |
8efc0c15 | 31 | { |
b4748e2f | 32 | extern ServerOptions options; |
8efc0c15 | 33 | const char *canonical_hostname; |
34 | HostStatus host_status; | |
35 | BIGNUM *ke, *kn; | |
36 | ||
37 | debug("Trying rhosts with RSA host authentication for %.100s", client_user); | |
38 | ||
39 | /* Check if we would accept it using rhosts authentication. */ | |
6fa724bc | 40 | if (!auth_rhosts(pw, client_user)) |
8efc0c15 | 41 | return 0; |
42 | ||
43 | canonical_hostname = get_canonical_hostname(); | |
44 | ||
45 | debug("Rhosts RSA authentication: canonical host %.900s", | |
46 | canonical_hostname); | |
47 | ||
48 | /* Check if we know the host and its host key. */ | |
49 | /* Check system-wide host file. */ | |
50 | ke = BN_new(); | |
51 | kn = BN_new(); | |
52 | host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname, | |
4d195447 | 53 | client_host_key_e, client_host_key_n, ke, kn); |
b4748e2f | 54 | |
55 | /* Check user host file unless ignored. */ | |
56 | if (host_status != HOST_OK && !options.ignore_user_known_hosts) { | |
5bbb5681 | 57 | struct stat st; |
58 | char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid); | |
59 | /* Check file permissions of SSH_USER_HOSTFILE, | |
60 | auth_rsa() did already check pw->pw_dir, but there is a race XXX */ | |
b4748e2f | 61 | if (options.strict_modes && |
5bbb5681 | 62 | (stat(user_hostfile, &st) == 0) && |
63 | ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || | |
64 | (st.st_mode & 022) != 0)) { | |
65 | log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s", | |
66 | pw->pw_name, user_hostfile); | |
67 | } else { | |
68 | /* XXX race between stat and the following open() */ | |
69 | temporarily_use_uid(pw->pw_uid); | |
70 | host_status = check_host_in_hostfile(user_hostfile, canonical_hostname, | |
4d195447 | 71 | client_host_key_e, client_host_key_n, ke, kn); |
5bbb5681 | 72 | restore_uid(); |
73 | } | |
74 | xfree(user_hostfile); | |
75 | } | |
8efc0c15 | 76 | BN_free(ke); |
77 | BN_free(kn); | |
5bbb5681 | 78 | |
8efc0c15 | 79 | if (host_status != HOST_OK) { |
80 | /* The host key was not found. */ | |
81 | debug("Rhosts with RSA host authentication denied: unknown or invalid host key"); | |
82 | packet_send_debug("Your host key cannot be verified: unknown or invalid host key."); | |
83 | return 0; | |
84 | } | |
85 | ||
86 | /* A matching host key was found and is known. */ | |
87 | ||
88 | /* Perform the challenge-response dialog with the client for the host key. */ | |
4d195447 | 89 | if (!auth_rsa_challenge_dialog(client_host_key_e, client_host_key_n)) |
8efc0c15 | 90 | { |
91 | log("Client on %.800s failed to respond correctly to host authentication.", | |
92 | canonical_hostname); | |
93 | return 0; | |
94 | } | |
95 | ||
96 | /* We have authenticated the user using .rhosts or /etc/hosts.equiv, and | |
97 | the host using RSA. We accept the authentication. */ | |
98 | ||
99 | log("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.", | |
100 | pw->pw_name, client_user, canonical_hostname); | |
101 | packet_send_debug("Rhosts with RSA host authentication accepted."); | |
102 | return 1; | |
103 | } |