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1/* $OpenBSD: auth.h,v 1.109 2026/02/06 01:24:36 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#include <stdio.h>
33
34#include <bsd_auth.h>
35#ifdef KRB5
36#include <krb5.h>
37#endif
38
39struct passwd;
40struct ssh;
41struct sshbuf;
42struct sshkey;
43struct sshkey_cert;
44struct sshauthopt;
45
46typedef struct Authctxt Authctxt;
47typedef struct Authmethod Authmethod;
48typedef struct KbdintDevice KbdintDevice;
49
50struct Authctxt {
51 sig_atomic_t success;
52 int authenticated; /* authenticated and alarms cancelled */
53 int postponed; /* authentication needs another step */
54 int valid; /* user exists and is allowed to login */
55 int attempt;
56 int failures;
57 int server_caused_failure;
58 int force_pwchange;
59 char *user; /* username sent by the client */
60 char *service;
61 struct passwd *pw; /* set if 'valid' */
62 char *style;
63
64 /* Method lists for multiple authentication */
65 char **auth_methods; /* modified from server config */
66 u_int num_auth_methods;
67
68 /* Authentication method-specific data */
69 void *methoddata;
70 void *kbdintctxt;
71 auth_session_t *as;
72#ifdef KRB5
73 krb5_context krb5_ctx;
74 krb5_ccache krb5_fwd_ccache;
75 krb5_principal krb5_user;
76 char *krb5_ticket_file;
77#endif
78
79 /* Authentication keys already used; these will be refused henceforth */
80 struct sshkey **prev_keys;
81 u_int nprev_keys;
82
83 /* Last used key and ancillary information from active auth method */
84 struct sshkey *auth_method_key;
85 char *auth_method_info;
86
87 /* Information exposed to session */
88 struct sshbuf *session_info; /* Auth info for environment */
89};
90
91/*
92 * Every authentication method has to handle authentication requests for
93 * non-existing users, or for users that are not allowed to login. In this
94 * case 'valid' is set to 0, but 'user' points to the username requested by
95 * the client.
96 */
97
98struct authmethod_cfg {
99 const char *name;
100 const char *synonym;
101 int *enabled;
102};
103
104struct Authmethod {
105 struct authmethod_cfg *cfg;
106 int (*userauth)(struct ssh *, const char *);
107};
108
109/*
110 * Keyboard interactive device:
111 * init_ctx returns: non NULL upon success
112 * query returns: 0 - success, otherwise failure
113 * respond returns: 0 - success, 1 - need further interaction,
114 * otherwise - failure
115 */
116struct KbdintDevice
117{
118 const char *name;
119 void* (*init_ctx)(Authctxt*);
120 int (*query)(void *ctx, char **name, char **infotxt,
121 u_int *numprompts, char ***prompts, u_int **echo_on);
122 int (*respond)(void *ctx, u_int numresp, char **responses);
123 void (*free_ctx)(void *ctx);
124};
125
126int
127auth_rhosts2(struct passwd *, const char *, const char *, const char *);
128
129int auth_password(struct ssh *, const char *);
130
131int hostbased_key_allowed(struct ssh *, struct passwd *,
132 const char *, char *, struct sshkey *);
133int user_key_allowed(struct ssh *ssh, struct passwd *, struct sshkey *,
134 int, struct sshauthopt **);
135int auth2_key_already_used(Authctxt *, const struct sshkey *);
136
137/*
138 * Handling auth method-specific information for logging and prevention
139 * of key reuse during multiple authentication.
140 */
141void auth2_authctxt_reset_info(Authctxt *);
142void auth2_record_key(Authctxt *, int, const struct sshkey *);
143void auth2_record_info(Authctxt *authctxt, const char *, ...)
144 __attribute__((__format__ (printf, 2, 3)))
145 __attribute__((__nonnull__ (2)));
146void auth2_update_session_info(Authctxt *, const char *, const char *);
147
148#ifdef KRB5
149int auth_krb5_password(Authctxt *authctxt, const char *password);
150void krb5_cleanup_proc(Authctxt *authctxt);
151#endif /* KRB5 */
152
153void do_authentication2(struct ssh *);
154
155void auth_log(struct ssh *, int, int, const char *, const char *);
156void auth_maxtries_exceeded(struct ssh *) __attribute__((noreturn));
157void userauth_finish(struct ssh *, int, const char *, const char *);
158int auth_root_allowed(struct ssh *, const char *);
159
160char *auth2_read_banner(void);
161int auth2_methods_valid(const char *, int);
162int auth2_update_methods_lists(Authctxt *, const char *, const char *);
163int auth2_setup_methods_lists(Authctxt *);
164int auth2_method_allowed(Authctxt *, const char *, const char *);
165
166int auth2_challenge(struct ssh *, char *);
167void auth2_challenge_stop(struct ssh *);
168int bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **);
169int bsdauth_respond(void *, u_int, char **);
170
171int allowed_user(struct ssh *, struct passwd *);
172struct passwd * getpwnamallow(struct ssh *, const char *user);
173
174char *expand_authorized_keys(const char *, struct passwd *pw);
175char *authorized_principals_file(struct passwd *);
176
177int auth_key_is_revoked(struct sshkey *);
178
179const char *auth_get_canonical_hostname(struct ssh *, int);
180
181HostStatus
182check_key_in_hostfiles(struct passwd *, struct sshkey *, const char *,
183 const char *, const char *);
184
185/* hostkey handling */
186struct sshkey *get_hostkey_by_index(int);
187struct sshkey *get_hostkey_public_by_index(int, struct ssh *);
188struct sshkey *get_hostkey_public_by_type(int, int, struct ssh *);
189struct sshkey *get_hostkey_private_by_type(int, int, struct ssh *);
190int get_hostkey_index(struct sshkey *, int, struct ssh *);
191int sshd_hostkey_sign(struct ssh *, struct sshkey *, struct sshkey *,
192 u_char **, size_t *, const u_char *, size_t, const char *);
193
194/* Key / cert options linkage to auth layer */
195int auth_activate_options(struct ssh *, struct sshauthopt *);
196void auth_restrict_session(struct ssh *);
197void auth_log_authopts(const char *, const struct sshauthopt *, int);
198
199/* debug messages during authentication */
200void auth_debug_add(const char *fmt,...)
201 __attribute__((format(printf, 1, 2)));
202void auth_debug_send(struct ssh *);
203void auth_debug_reset(void);
204
205struct passwd *fakepw(void);
206
207/* auth2-pubkeyfile.c */
208int auth_authorise_keyopts(struct passwd *, struct sshauthopt *, int,
209 const char *, const char *, const char *);
210int auth_check_principals_line(char *, const struct sshkey_cert *,
211 const char *, struct sshauthopt **);
212int auth_process_principals(FILE *, const char *,
213 const struct sshkey_cert *, struct sshauthopt **);
214int auth_check_authkey_line(struct passwd *, struct sshkey *,
215 char *, const char *, const char *, const char *, struct sshauthopt **);
216int auth_check_authkeys_file(struct passwd *, FILE *, char *,
217 struct sshkey *, const char *, const char *, struct sshauthopt **);
218FILE *auth_openkeyfile(const char *, struct passwd *, int);
219FILE *auth_openprincipals(const char *, struct passwd *, int);
220
221#endif