xref: /openssh-portable/auth.h (revision 04c091fc)
1 /* $OpenBSD: auth.h,v 1.99 2019/01/19 21:43:56 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 #include <openssl/rsa.h>
34 
35 #ifdef HAVE_LOGIN_CAP
36 #include <login_cap.h>
37 #endif
38 #ifdef BSD_AUTH
39 #include <bsd_auth.h>
40 #endif
41 #ifdef KRB5
42 #include <krb5.h>
43 #endif
44 
45 struct passwd;
46 struct ssh;
47 struct sshbuf;
48 struct sshkey;
49 struct sshauthopt;
50 
51 typedef struct Authctxt Authctxt;
52 typedef struct Authmethod Authmethod;
53 typedef struct KbdintDevice KbdintDevice;
54 
55 struct Authctxt {
56 	sig_atomic_t	 success;
57 	int		 authenticated;	/* authenticated and alarms cancelled */
58 	int		 postponed;	/* authentication needs another step */
59 	int		 valid;		/* user exists and is allowed to login */
60 	int		 attempt;
61 	int		 failures;
62 	int		 server_caused_failure;
63 	int		 force_pwchange;
64 	char		*user;		/* username sent by the client */
65 	char		*service;
66 	struct passwd	*pw;		/* set if 'valid' */
67 	char		*style;
68 
69 	/* Method lists for multiple authentication */
70 	char		**auth_methods;	/* modified from server config */
71 	u_int		 num_auth_methods;
72 
73 	/* Authentication method-specific data */
74 	void		*methoddata;
75 	void		*kbdintctxt;
76 #ifdef BSD_AUTH
77 	auth_session_t	*as;
78 #endif
79 #ifdef KRB5
80 	krb5_context	 krb5_ctx;
81 	krb5_ccache	 krb5_fwd_ccache;
82 	krb5_principal	 krb5_user;
83 	char		*krb5_ticket_file;
84 	char		*krb5_ccname;
85 #endif
86 	struct sshbuf	*loginmsg;
87 
88 	/* Authentication keys already used; these will be refused henceforth */
89 	struct sshkey	**prev_keys;
90 	u_int		 nprev_keys;
91 
92 	/* Last used key and ancillary information from active auth method */
93 	struct sshkey	*auth_method_key;
94 	char		*auth_method_info;
95 
96 	/* Information exposed to session */
97 	struct sshbuf	*session_info;	/* Auth info for environment */
98 };
99 
100 /*
101  * Every authentication method has to handle authentication requests for
102  * non-existing users, or for users that are not allowed to login. In this
103  * case 'valid' is set to 0, but 'user' points to the username requested by
104  * the client.
105  */
106 
107 struct Authmethod {
108 	char	*name;
109 	int	(*userauth)(struct ssh *);
110 	int	*enabled;
111 };
112 
113 /*
114  * Keyboard interactive device:
115  * init_ctx	returns: non NULL upon success
116  * query	returns: 0 - success, otherwise failure
117  * respond	returns: 0 - success, 1 - need further interaction,
118  *		otherwise - failure
119  */
120 struct KbdintDevice
121 {
122 	const char *name;
123 	void*	(*init_ctx)(Authctxt*);
124 	int	(*query)(void *ctx, char **name, char **infotxt,
125 		    u_int *numprompts, char ***prompts, u_int **echo_on);
126 	int	(*respond)(void *ctx, u_int numresp, char **responses);
127 	void	(*free_ctx)(void *ctx);
128 };
129 
130 int
131 auth_rhosts2(struct passwd *, const char *, const char *, const char *);
132 
133 int      auth_password(struct ssh *, const char *);
134 
135 int	 hostbased_key_allowed(struct ssh *, struct passwd *,
136 	    const char *, char *, struct sshkey *);
137 int	 user_key_allowed(struct ssh *, struct passwd *, struct sshkey *, int,
138     struct sshauthopt **);
139 int	 auth2_key_already_used(Authctxt *, const struct sshkey *);
140 
141 /*
142  * Handling auth method-specific information for logging and prevention
143  * of key reuse during multiple authentication.
144  */
145 void	 auth2_authctxt_reset_info(Authctxt *);
146 void	 auth2_record_key(Authctxt *, int, const struct sshkey *);
147 void	 auth2_record_info(Authctxt *authctxt, const char *, ...)
148 	    __attribute__((__format__ (printf, 2, 3)))
149 	    __attribute__((__nonnull__ (2)));
150 void	 auth2_update_session_info(Authctxt *, const char *, const char *);
151 
152 #ifdef KRB5
153 int	auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *);
154 int	auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt);
155 int	auth_krb5_password(Authctxt *authctxt, const char *password);
156 void	krb5_cleanup_proc(Authctxt *authctxt);
157 #endif /* KRB5 */
158 
159 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
160 #include <shadow.h>
161 int auth_shadow_acctexpired(struct spwd *);
162 int auth_shadow_pwexpired(Authctxt *);
163 #endif
164 
165 #include "auth-pam.h"
166 #include "audit.h"
167 void remove_kbdint_device(const char *);
168 
169 void	do_authentication2(struct ssh *);
170 
171 void	auth_log(struct ssh *, int, int, const char *, const char *);
172 void	auth_maxtries_exceeded(struct ssh *) __attribute__((noreturn));
173 void	userauth_finish(struct ssh *, int, const char *, const char *);
174 int	auth_root_allowed(struct ssh *, const char *);
175 
176 char	*auth2_read_banner(void);
177 int	 auth2_methods_valid(const char *, int);
178 int	 auth2_update_methods_lists(Authctxt *, const char *, const char *);
179 int	 auth2_setup_methods_lists(Authctxt *);
180 int	 auth2_method_allowed(Authctxt *, const char *, const char *);
181 
182 void	privsep_challenge_enable(void);
183 
184 int	auth2_challenge(struct ssh *, char *);
185 void	auth2_challenge_stop(struct ssh *);
186 int	bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **);
187 int	bsdauth_respond(void *, u_int, char **);
188 
189 int	allowed_user(struct ssh *, struct passwd *);
190 struct passwd * getpwnamallow(struct ssh *, const char *user);
191 
192 char	*expand_authorized_keys(const char *, struct passwd *pw);
193 char	*authorized_principals_file(struct passwd *);
194 
195 FILE	*auth_openkeyfile(const char *, struct passwd *, int);
196 FILE	*auth_openprincipals(const char *, struct passwd *, int);
197 int	 auth_key_is_revoked(struct sshkey *);
198 
199 const char	*auth_get_canonical_hostname(struct ssh *, int);
200 
201 HostStatus
202 check_key_in_hostfiles(struct passwd *, struct sshkey *, const char *,
203     const char *, const char *);
204 
205 /* hostkey handling */
206 struct sshkey	*get_hostkey_by_index(int);
207 struct sshkey	*get_hostkey_public_by_index(int, struct ssh *);
208 struct sshkey	*get_hostkey_public_by_type(int, int, struct ssh *);
209 struct sshkey	*get_hostkey_private_by_type(int, int, struct ssh *);
210 int	 get_hostkey_index(struct sshkey *, int, struct ssh *);
211 int	 sshd_hostkey_sign(struct ssh *, struct sshkey *, struct sshkey *,
212     u_char **, size_t *, const u_char *, size_t, const char *);
213 
214 /* Key / cert options linkage to auth layer */
215 const struct sshauthopt *auth_options(struct ssh *);
216 int	 auth_activate_options(struct ssh *, struct sshauthopt *);
217 void	 auth_restrict_session(struct ssh *);
218 int	 auth_authorise_keyopts(struct ssh *, struct passwd *pw,
219     struct sshauthopt *, int, const char *);
220 void	 auth_log_authopts(const char *, const struct sshauthopt *, int);
221 
222 /* debug messages during authentication */
223 void	 auth_debug_add(const char *fmt,...)
224     __attribute__((format(printf, 1, 2)));
225 void	 auth_debug_send(struct ssh *);
226 void	 auth_debug_reset(void);
227 
228 struct passwd *fakepw(void);
229 
230 #define	SSH_SUBPROCESS_STDOUT_DISCARD  (1)     /* Discard stdout */
231 #define	SSH_SUBPROCESS_STDOUT_CAPTURE  (1<<1)  /* Redirect stdout */
232 #define	SSH_SUBPROCESS_STDERR_DISCARD  (1<<2)  /* Discard stderr */
233 pid_t	subprocess(const char *, struct passwd *,
234     const char *, int, char **, FILE **, u_int flags);
235 
236 int	 sys_auth_passwd(struct ssh *, const char *);
237 
238 #if defined(KRB5) && !defined(HEIMDAL)
239 #include <krb5.h>
240 krb5_error_code ssh_krb5_cc_gen(krb5_context, krb5_ccache *);
241 #endif
242 #endif
243