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auth.h
1 /* $OpenBSD: auth.h,v 1.101 2020/12/22 00:12:22 djm Exp $ */
2 
3 /*
4  * Copyright (c) 2000 Markus Friedl. All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  *
26  */
27 
28 #ifndef AUTH_H
29 #define AUTH_H
30 
31 #include <signal.h>
32 
33 #ifdef HAVE_LOGIN_CAP
34 #include <login_cap.h>
35 #endif
36 #ifdef BSD_AUTH
37 #include <bsd_auth.h>
38 #endif
39 #ifdef KRB5
40 #include <krb5.h>
41 #endif
42 
43 struct passwd;
44 struct ssh;
45 struct sshbuf;
46 struct sshkey;
47 struct sshauthopt;
48 
49 typedef struct Authctxt Authctxt;
50 typedef struct Authmethod Authmethod;
51 typedef struct KbdintDevice KbdintDevice;
52 
53 struct Authctxt {
54  sig_atomic_t success;
55  int authenticated; /* authenticated and alarms cancelled */
56  int postponed; /* authentication needs another step */
57  int valid; /* user exists and is allowed to login */
58  int attempt;
59  int failures;
60  int server_caused_failure;
61  int force_pwchange;
62  char *user; /* username sent by the client */
63  char *service;
64  struct passwd *pw; /* set if 'valid' */
65  char *style;
66 #ifdef WITH_SELINUX
67  char *role;
68 #endif
69 
70  /* Method lists for multiple authentication */
71  char **auth_methods; /* modified from server config */
72  u_int num_auth_methods;
73 
74  /* Authentication method-specific data */
75  void *methoddata;
76  void *kbdintctxt;
77 #ifdef BSD_AUTH
78  auth_session_t *as;
79 #endif
80 #ifdef KRB5
81  krb5_context krb5_ctx;
82  krb5_ccache krb5_fwd_ccache;
83  krb5_principal krb5_user;
84  char *krb5_ticket_file;
85  char *krb5_ccname;
86 #endif
87 #ifdef GSSAPI
88  int krb5_set_env;
89 #endif
90  struct sshbuf *loginmsg;
91 
92  /* Authentication keys already used; these will be refused henceforth */
93  struct sshkey **prev_keys;
94  u_int nprev_keys;
95 
96  /* Last used key and ancillary information from active auth method */
97  struct sshkey *auth_method_key;
98  char *auth_method_info;
99 
100  /* Information exposed to session */
101  struct sshbuf *session_info; /* Auth info for environment */
102 };
103 
104 /*
105  * Every authentication method has to handle authentication requests for
106  * non-existing users, or for users that are not allowed to login. In this
107  * case 'valid' is set to 0, but 'user' points to the username requested by
108  * the client.
109  */
110 
111 struct Authmethod {
112  char *name;
113  int (*userauth)(struct ssh *);
114  int *enabled;
115 };
116 
117 /*
118  * Keyboard interactive device:
119  * init_ctx returns: non NULL upon success
120  * query returns: 0 - success, otherwise failure
121  * respond returns: 0 - success, 1 - need further interaction,
122  * otherwise - failure
123  */
124 struct KbdintDevice
125 {
126  const char *name;
127  void* (*init_ctx)(Authctxt*);
128  int (*query)(void *ctx, char **name, char **infotxt,
129  u_int *numprompts, char ***prompts, u_int **echo_on);
130  int (*respond)(void *ctx, u_int numresp, char **responses);
131  void (*free_ctx)(void *ctx);
132 };
133 
134 int
135 auth_rhosts2(struct passwd *, const char *, const char *, const char *);
136 
137 int auth_password(struct ssh *, const char *);
138 
139 int hostbased_key_allowed(struct ssh *, struct passwd *,
140  const char *, char *, struct sshkey *);
141 int user_key_allowed(struct ssh *, struct passwd *, struct sshkey *, int,
142  struct sshauthopt **);
143 int auth2_key_already_used(Authctxt *, const struct sshkey *);
144 
145 /*
146  * Handling auth method-specific information for logging and prevention
147  * of key reuse during multiple authentication.
148  */
149 void auth2_authctxt_reset_info(Authctxt *);
150 void auth2_record_key(Authctxt *, int, const struct sshkey *);
151 void auth2_record_info(Authctxt *authctxt, const char *, ...)
152  __attribute__((__format__ (printf, 2, 3)))
153  __attribute__((__nonnull__ (2)));
154 void auth2_update_session_info(Authctxt *, const char *, const char *);
155 
156 #ifdef KRB5
157 int auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *);
158 int auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt);
159 int auth_krb5_password(Authctxt *authctxt, const char *password);
160 void krb5_cleanup_proc(Authctxt *authctxt);
161 #endif /* KRB5 */
162 
163 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
164 #include <shadow.h>
165 int auth_shadow_acctexpired(struct spwd *);
166 int auth_shadow_pwexpired(Authctxt *);
167 #endif
168 
169 #include "auth-pam.h"
170 #include "audit.h"
171 void remove_kbdint_device(const char *);
172 
173 void do_authentication2(struct ssh *);
174 
175 void auth_log(struct ssh *, int, int, const char *, const char *);
176 void auth_maxtries_exceeded(struct ssh *) __attribute__((noreturn));
177 void userauth_finish(struct ssh *, int, const char *, const char *);
178 int auth_root_allowed(struct ssh *, const char *);
179 
180 char *auth2_read_banner(void);
181 int auth2_methods_valid(const char *, int);
182 int auth2_update_methods_lists(Authctxt *, const char *, const char *);
183 int auth2_setup_methods_lists(Authctxt *);
184 int auth2_method_allowed(Authctxt *, const char *, const char *);
185 
186 void privsep_challenge_enable(void);
187 
188 int auth2_challenge(struct ssh *, char *);
189 void auth2_challenge_stop(struct ssh *);
190 int bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **);
191 int bsdauth_respond(void *, u_int, char **);
192 
193 int allowed_user(struct ssh *, struct passwd *);
194 struct passwd * getpwnamallow(struct ssh *, const char *user);
195 
196 char *expand_authorized_keys(const char *, struct passwd *pw);
197 char *authorized_principals_file(struct passwd *);
198 int user_key_verify(struct ssh *, const struct sshkey *, const u_char *, size_t,
199  const u_char *, size_t, const char *, u_int, struct sshkey_sig_details **);
200 
201 FILE *auth_openkeyfile(const char *, struct passwd *, int);
202 FILE *auth_openprincipals(const char *, struct passwd *, int);
203 int auth_key_is_revoked(struct sshkey *);
204 
205 const char *auth_get_canonical_hostname(struct ssh *, int);
206 
207 HostStatus
208 check_key_in_hostfiles(struct passwd *, struct sshkey *, const char *,
209  const char *, const char *);
210 
211 /* hostkey handling */
212 struct sshkey *get_hostkey_by_index(int);
213 struct sshkey *get_hostkey_public_by_index(int, struct ssh *);
214 struct sshkey *get_hostkey_public_by_type(int, int, struct ssh *);
215 struct sshkey *get_hostkey_private_by_type(int, int, struct ssh *);
216 int get_hostkey_index(struct sshkey *, int, struct ssh *);
217 int sshd_hostkey_sign(struct ssh *, struct sshkey *, struct sshkey *,
218  u_char **, size_t *, const u_char *, size_t, const char *);
219 int hostbased_key_verify(struct ssh *, const struct sshkey *, const u_char *, size_t,
220  const u_char *, size_t, const char *, u_int, struct sshkey_sig_details **);
221 
222 /* Key / cert options linkage to auth layer */
223 const struct sshauthopt *auth_options(struct ssh *);
224 int auth_activate_options(struct ssh *, struct sshauthopt *);
225 void auth_restrict_session(struct ssh *);
226 int auth_authorise_keyopts(struct ssh *, struct passwd *pw,
227  struct sshauthopt *, int, const char *);
228 void auth_log_authopts(const char *, const struct sshauthopt *, int);
229 
230 /* debug messages during authentication */
231 void auth_debug_add(const char *fmt,...)
232  __attribute__((format(printf, 1, 2)));
233 void auth_debug_send(struct ssh *);
234 void auth_debug_reset(void);
235 
236 struct passwd *fakepw(void);
237 
238 int sys_auth_passwd(struct ssh *, const char *);
239 
240 #if defined(KRB5) && !defined(HEIMDAL)
241 krb5_error_code ssh_krb5_cc_new_unique(krb5_context, krb5_ccache *, int *);
242 krb5_error_code ssh_krb5_get_k5login_directory(krb5_context ctx,
243  char **k5login_directory);
244 #endif
245 
246 #endif /* AUTH_H */
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