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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, | |
30 | unsigned int client_host_key_bits, | |
b4748e2f | 31 | BIGNUM *client_host_key_e, BIGNUM *client_host_key_n) |
8efc0c15 | 32 | { |
b4748e2f | 33 | extern ServerOptions options; |
8efc0c15 | 34 | const char *canonical_hostname; |
35 | HostStatus host_status; | |
36 | BIGNUM *ke, *kn; | |
37 | ||
38 | debug("Trying rhosts with RSA host authentication for %.100s", client_user); | |
39 | ||
40 | /* Check if we would accept it using rhosts authentication. */ | |
b4748e2f | 41 | if (!auth_rhosts(pw, client_user, options.ignore_rhosts, options.strict_modes)) |
8efc0c15 | 42 | return 0; |
43 | ||
44 | canonical_hostname = get_canonical_hostname(); | |
45 | ||
46 | debug("Rhosts RSA authentication: canonical host %.900s", | |
47 | canonical_hostname); | |
48 | ||
49 | /* Check if we know the host and its host key. */ | |
50 | /* Check system-wide host file. */ | |
51 | ke = BN_new(); | |
52 | kn = BN_new(); | |
53 | host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname, | |
54 | client_host_key_bits, client_host_key_e, | |
55 | client_host_key_n, ke, kn); | |
b4748e2f | 56 | |
57 | /* Check user host file unless ignored. */ | |
58 | if (host_status != HOST_OK && !options.ignore_user_known_hosts) { | |
5bbb5681 | 59 | struct stat st; |
60 | char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid); | |
61 | /* Check file permissions of SSH_USER_HOSTFILE, | |
62 | auth_rsa() did already check pw->pw_dir, but there is a race XXX */ | |
b4748e2f | 63 | if (options.strict_modes && |
5bbb5681 | 64 | (stat(user_hostfile, &st) == 0) && |
65 | ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || | |
66 | (st.st_mode & 022) != 0)) { | |
67 | log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s", | |
68 | pw->pw_name, user_hostfile); | |
69 | } else { | |
70 | /* XXX race between stat and the following open() */ | |
71 | temporarily_use_uid(pw->pw_uid); | |
72 | host_status = check_host_in_hostfile(user_hostfile, canonical_hostname, | |
73 | client_host_key_bits, client_host_key_e, | |
74 | client_host_key_n, ke, kn); | |
75 | restore_uid(); | |
76 | } | |
77 | xfree(user_hostfile); | |
78 | } | |
8efc0c15 | 79 | BN_free(ke); |
80 | BN_free(kn); | |
5bbb5681 | 81 | |
8efc0c15 | 82 | if (host_status != HOST_OK) { |
83 | /* The host key was not found. */ | |
84 | debug("Rhosts with RSA host authentication denied: unknown or invalid host key"); | |
85 | packet_send_debug("Your host key cannot be verified: unknown or invalid host key."); | |
86 | return 0; | |
87 | } | |
88 | ||
89 | /* A matching host key was found and is known. */ | |
90 | ||
91 | /* Perform the challenge-response dialog with the client for the host key. */ | |
92 | if (!auth_rsa_challenge_dialog(client_host_key_bits, | |
93 | client_host_key_e, client_host_key_n)) | |
94 | { | |
95 | log("Client on %.800s failed to respond correctly to host authentication.", | |
96 | canonical_hostname); | |
97 | return 0; | |
98 | } | |
99 | ||
100 | /* We have authenticated the user using .rhosts or /etc/hosts.equiv, and | |
101 | the host using RSA. We accept the authentication. */ | |
102 | ||
103 | log("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.", | |
104 | pw->pw_name, client_user, canonical_hostname); | |
105 | packet_send_debug("Rhosts with RSA host authentication accepted."); | |
106 | return 1; | |
107 | } |