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8efc0c15 | 1 | /* |
2 | ||
3 | auth-passwd.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: Sat Mar 18 05:11:38 1995 ylo | |
11 | ||
12 | Password authentication. This file contains the functions to check whether | |
13 | the password is valid for the user. | |
14 | ||
15 | */ | |
16 | ||
17 | #include "includes.h" | |
18 | RCSID("$Id$"); | |
19 | ||
20 | #include "packet.h" | |
21 | #include "ssh.h" | |
22 | #include "servconf.h" | |
23 | #include "xmalloc.h" | |
24 | ||
25 | #ifdef KRB4 | |
26 | extern char *ticket; | |
27 | #endif /* KRB4 */ | |
28 | ||
29 | #ifdef HAVE_PAM | |
30 | #include <security/pam_appl.h> | |
31 | extern pam_handle_t *pamh; | |
32 | extern int retval; | |
33 | extern char* pampasswd; | |
34 | extern int origretval; | |
35 | #endif /* HAVE_PAM */ | |
36 | ||
37 | /* Tries to authenticate the user using password. Returns true if | |
38 | authentication succeeds. */ | |
39 | ||
40 | int auth_password(struct passwd *pw, const char *password) | |
41 | { | |
42 | extern ServerOptions options; | |
43 | char *encrypted_password; | |
44 | ||
45 | if (pw->pw_uid == 0 && options.permit_root_login == 2) | |
46 | { | |
47 | /*packet_send_debug("Server does not permit root login with password.");*/ | |
48 | return 0; | |
49 | } | |
50 | ||
51 | if (*password == '\0' && options.permit_empty_passwd == 0) | |
52 | { | |
53 | /*packet_send_debug("Server does not permit empty password login.");*/ | |
54 | return 0; | |
55 | } | |
56 | ||
57 | /* deny if no user. */ | |
58 | if (pw == NULL) | |
59 | return 0; | |
60 | ||
61 | #ifdef HAVE_PAM | |
62 | retval = origretval; | |
63 | ||
64 | pampasswd = xstrdup(password); | |
65 | ||
66 | if (retval == PAM_SUCCESS) | |
67 | retval = pam_authenticate ((pam_handle_t *)pamh, 0); | |
68 | ||
69 | if (retval == PAM_SUCCESS) | |
70 | retval = pam_acct_mgmt ((pam_handle_t *)pamh, 0); | |
71 | ||
72 | xfree(pampasswd); | |
73 | ||
74 | if (retval == PAM_SUCCESS) | |
75 | retval = pam_open_session ((pam_handle_t *)pamh, 0); | |
76 | ||
77 | return (retval == PAM_SUCCESS); | |
78 | ||
79 | #else /* HAVE_PAM */ | |
80 | ||
81 | #ifdef SKEY | |
82 | if (options.skey_authentication == 1) { | |
83 | if (strncasecmp(password, "s/key", 5) == 0) { | |
84 | char *skeyinfo = skey_keyinfo(pw->pw_name); | |
85 | if(skeyinfo == NULL){ | |
86 | debug("generating fake skeyinfo for %.100s.", pw->pw_name); | |
87 | skeyinfo = skey_fake_keyinfo(pw->pw_name); | |
88 | } | |
89 | if(skeyinfo != NULL) | |
90 | packet_send_debug(skeyinfo); | |
91 | /* Try again. */ | |
92 | return 0; | |
93 | } | |
94 | else if (skey_haskey(pw->pw_name) == 0 && | |
95 | skey_passcheck(pw->pw_name, (char *)password) != -1) { | |
96 | /* Authentication succeeded. */ | |
97 | return 1; | |
98 | } | |
99 | /* Fall back to ordinary passwd authentication. */ | |
100 | } | |
101 | #endif | |
102 | ||
103 | #if defined(KRB4) | |
104 | /* Support for Kerberos v4 authentication - Dug Song <dugsong@UMICH.EDU> */ | |
105 | if (options.kerberos_authentication) | |
106 | { | |
107 | AUTH_DAT adata; | |
108 | KTEXT_ST tkt; | |
109 | struct hostent *hp; | |
110 | unsigned long faddr; | |
111 | char localhost[MAXHOSTNAMELEN]; /* local host name */ | |
112 | char phost[INST_SZ]; /* host instance */ | |
113 | char realm[REALM_SZ]; /* local Kerberos realm */ | |
114 | int r; | |
115 | ||
116 | /* Try Kerberos password authentication only for non-root | |
117 | users and only if Kerberos is installed. */ | |
118 | if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) { | |
119 | ||
120 | /* Set up our ticket file. */ | |
121 | if (!ssh_tf_init(pw->pw_uid)) { | |
122 | log("Couldn't initialize Kerberos ticket file for %s!", | |
123 | pw->pw_name); | |
124 | goto kerberos_auth_failure; | |
125 | } | |
126 | /* Try to get TGT using our password. */ | |
127 | r = krb_get_pw_in_tkt((char *)pw->pw_name, "", realm, "krbtgt", realm, | |
128 | DEFAULT_TKT_LIFE, (char *)password); | |
129 | if (r != INTK_OK) { | |
130 | packet_send_debug("Kerberos V4 password authentication for %s " | |
131 | "failed: %s", pw->pw_name, krb_err_txt[r]); | |
132 | goto kerberos_auth_failure; | |
133 | } | |
134 | /* Successful authentication. */ | |
135 | chown(ticket, pw->pw_uid, pw->pw_gid); | |
136 | ||
137 | (void) gethostname(localhost, sizeof(localhost)); | |
138 | (void) strlcpy(phost, (char *)krb_get_phost(localhost), INST_SZ); | |
139 | ||
140 | /* Now that we have a TGT, try to get a local "rcmd" ticket to | |
141 | ensure that we are not talking to a bogus Kerberos server. */ | |
142 | r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33); | |
143 | ||
144 | if (r == KSUCCESS) { | |
145 | if (!(hp = gethostbyname(localhost))) { | |
146 | log("Couldn't get local host address!"); | |
147 | goto kerberos_auth_failure; | |
148 | } | |
149 | memmove((void *)&faddr, (void *)hp->h_addr, sizeof(faddr)); | |
150 | ||
151 | /* Verify our "rcmd" ticket. */ | |
152 | r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost, faddr, &adata, ""); | |
153 | if (r == RD_AP_UNDEC) { | |
154 | /* Probably didn't have a srvtab on localhost. Allow login. */ | |
155 | log("Kerberos V4 TGT for %s unverifiable, no srvtab installed? " | |
156 | "krb_rd_req: %s", pw->pw_name, krb_err_txt[r]); | |
157 | } | |
158 | else if (r != KSUCCESS) { | |
159 | log("Kerberos V4 %s ticket unverifiable: %s", | |
160 | KRB4_SERVICE_NAME, krb_err_txt[r]); | |
161 | goto kerberos_auth_failure; | |
162 | } | |
163 | } | |
164 | else if (r == KDC_PR_UNKNOWN) { | |
165 | /* Allow login if no rcmd service exists, but log the error. */ | |
166 | log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s " | |
167 | "not registered, or srvtab is wrong?", pw->pw_name, | |
168 | krb_err_txt[r], KRB4_SERVICE_NAME, phost); | |
169 | } | |
170 | else { | |
171 | /* TGT is bad, forget it. Possibly spoofed! */ | |
172 | packet_send_debug("WARNING: Kerberos V4 TGT possibly spoofed for" | |
173 | "%s: %s", pw->pw_name, krb_err_txt[r]); | |
174 | goto kerberos_auth_failure; | |
175 | } | |
176 | ||
177 | /* Authentication succeeded. */ | |
178 | return 1; | |
179 | ||
180 | kerberos_auth_failure: | |
181 | (void) dest_tkt(); | |
182 | xfree(ticket); | |
183 | ticket = NULL; | |
184 | if (!options.kerberos_or_local_passwd ) return 0; | |
185 | } | |
186 | else { | |
187 | /* Logging in as root or no local Kerberos realm. */ | |
188 | packet_send_debug("Unable to authenticate to Kerberos."); | |
189 | } | |
190 | /* Fall back to ordinary passwd authentication. */ | |
191 | } | |
192 | #endif /* KRB4 */ | |
193 | ||
194 | /* Check for users with no password. */ | |
195 | if (strcmp(password, "") == 0 && strcmp(pw->pw_passwd, "") == 0) | |
196 | { | |
197 | packet_send_debug("Login permitted without a password because the account has no password."); | |
198 | return 1; /* The user has no password and an empty password was tried. */ | |
199 | } | |
200 | ||
201 | /* Encrypt the candidate password using the proper salt. */ | |
202 | encrypted_password = crypt(password, | |
203 | (pw->pw_passwd[0] && pw->pw_passwd[1]) ? | |
204 | pw->pw_passwd : "xx"); | |
205 | ||
206 | /* Authentication is accepted if the encrypted passwords are identical. */ | |
207 | return (strcmp(encrypted_password, pw->pw_passwd) == 0); | |
208 | #endif /* HAVE_PAM */ | |
209 | } |