auth.h

   1 /* $OpenBSD: auth.h,v 1.106 2022/06/15 16:08:25 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 #ifdef HAVE_LOGIN_CAP
  35 #include <login_cap.h>
  36 #endif
  37 #ifdef BSD_AUTH
  38 #include <bsd_auth.h>
  39 #endif
  40 #ifdef KRB5
  41 #include <krb5.h>
  42 #endif
  43
  44 struct passwd;
  45 struct ssh;
  46 struct sshbuf;
  47 struct sshkey;
  48 struct sshkey_cert;
  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         char    *synonym;
 110         int     (*userauth)(struct ssh *, const char *);
 111         int     *enabled;
 112 };
 113
 114 /*
 115  * Keyboard interactive device:
 116  * init_ctx     returns: non NULL upon success
 117  * query        returns: 0 - success, otherwise failure
 118  * respond      returns: 0 - success, 1 - need further interaction,
 119  *              otherwise - failure
 120  */
 121 struct KbdintDevice
 122 {
 123         const char *name;
 124         void*   (*init_ctx)(Authctxt*);
 125         int     (*query)(void *ctx, char **name, char **infotxt,
 126                     u_int *numprompts, char ***prompts, u_int **echo_on);
 127         int     (*respond)(void *ctx, u_int numresp, char **responses);
 128         void    (*free_ctx)(void *ctx);
 129 };
 130
 131 int
 132 auth_rhosts2(struct passwd *, const char *, const char *, const char *);
 133
 134 int      auth_password(struct ssh *, const char *);
 135
 136 int      hostbased_key_allowed(struct ssh *, struct passwd *,
 137             const char *, char *, struct sshkey *);
 138 int      user_key_allowed(struct ssh *ssh, struct passwd *, struct sshkey *,
 139     int, struct sshauthopt **);
 140 int      auth2_key_already_used(Authctxt *, const struct sshkey *);
 141
 142 /*
 143  * Handling auth method-specific information for logging and prevention
 144  * of key reuse during multiple authentication.
 145  */
 146 void     auth2_authctxt_reset_info(Authctxt *);
 147 void     auth2_record_key(Authctxt *, int, const struct sshkey *);
 148 void     auth2_record_info(Authctxt *authctxt, const char *, ...)
 149             __attribute__((__format__ (printf, 2, 3)))
 150             __attribute__((__nonnull__ (2)));
 151 void     auth2_update_session_info(Authctxt *, const char *, const char *);
 152
 153 #ifdef KRB5
 154 int     auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *);
 155 int     auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt);
 156 int     auth_krb5_password(Authctxt *authctxt, const char *password);
 157 void    krb5_cleanup_proc(Authctxt *authctxt);
 158 #endif /* KRB5 */
 159
 160 #if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
 161 #include <shadow.h>
 162 int auth_shadow_acctexpired(struct spwd *);
 163 int auth_shadow_pwexpired(Authctxt *);
 164 #endif
 165
 166 #include "auth-pam.h"
 167 #include "audit.h"
 168 void remove_kbdint_device(const char *);
 169
 170 void    do_authentication2(struct ssh *);
 171
 172 void    auth_log(struct ssh *, int, int, const char *, const char *);
 173 void    auth_maxtries_exceeded(struct ssh *) __attribute__((noreturn));
 174 void    userauth_finish(struct ssh *, int, const char *, const char *);
 175 int     auth_root_allowed(struct ssh *, const char *);
 176
 177 char    *auth2_read_banner(void);
 178 int      auth2_methods_valid(const char *, int);
 179 int      auth2_update_methods_lists(Authctxt *, const char *, const char *);
 180 int      auth2_setup_methods_lists(Authctxt *);
 181 int      auth2_method_allowed(Authctxt *, const char *, const char *);
 182
 183 void    privsep_challenge_enable(void);
 184
 185 int     auth2_challenge(struct ssh *, char *);
 186 void    auth2_challenge_stop(struct ssh *);
 187 int     bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **);
 188 int     bsdauth_respond(void *, u_int, char **);
 189
 190 int     allowed_user(struct ssh *, struct passwd *);
 191 struct passwd * getpwnamallow(struct ssh *, const char *user);
 192
 193 char    *expand_authorized_keys(const char *, struct passwd *pw);
 194 char    *authorized_principals_file(struct passwd *);
 195
 196 int      auth_key_is_revoked(struct sshkey *);
 197
 198 const char      *auth_get_canonical_hostname(struct ssh *, int);
 199
 200 HostStatus
 201 check_key_in_hostfiles(struct passwd *, struct sshkey *, const char *,
 202     const char *, const char *);
 203
 204 /* hostkey handling */
 205 struct sshkey   *get_hostkey_by_index(int);
 206 struct sshkey   *get_hostkey_public_by_index(int, struct ssh *);
 207 struct sshkey   *get_hostkey_public_by_type(int, int, struct ssh *);
 208 struct sshkey   *get_hostkey_private_by_type(int, int, struct ssh *);
 209 int      get_hostkey_index(struct sshkey *, int, struct ssh *);
 210 int      sshd_hostkey_sign(struct ssh *, struct sshkey *, struct sshkey *,
 211     u_char **, size_t *, const u_char *, size_t, const char *);
 212
 213 /* Key / cert options linkage to auth layer */
 214 const struct sshauthopt *auth_options(struct ssh *);
 215 int      auth_activate_options(struct ssh *, struct sshauthopt *);
 216 void     auth_restrict_session(struct ssh *);
 217 void     auth_log_authopts(const char *, const struct sshauthopt *, int);
 218
 219 /* debug messages during authentication */
 220 void     auth_debug_add(const char *fmt,...)
 221     __attribute__((format(printf, 1, 2)));
 222 void     auth_debug_send(struct ssh *);
 223 void     auth_debug_reset(void);
 224
 225 struct passwd *fakepw(void);
 226
 227 /* auth2-pubkeyfile.c */
 228 int      auth_authorise_keyopts(struct passwd *, struct sshauthopt *, int,
 229     const char *, const char *, const char *);
 230 int      auth_check_principals_line(char *, const struct sshkey_cert *,
 231     const char *, struct sshauthopt **);
 232 int      auth_process_principals(FILE *, const char *,
 233     const struct sshkey_cert *, struct sshauthopt **);
 234 int      auth_check_authkey_line(struct passwd *, struct sshkey *,
 235     char *, const char *, const char *, const char *, struct sshauthopt **);
 236 int      auth_check_authkeys_file(struct passwd *, FILE *, char *,
 237     struct sshkey *, const char *, const char *, struct sshauthopt **);
 238 FILE    *auth_openkeyfile(const char *, struct passwd *, int);
 239 FILE    *auth_openprincipals(const char *, struct passwd *, int);
 240
 241 int      sys_auth_passwd(struct ssh *, const char *);
 242
 243 #if defined(KRB5) && !defined(HEIMDAL)
 244 krb5_error_code ssh_krb5_cc_gen(krb5_context, krb5_ccache *);
 245 #endif
 246
 247 #endif /* AUTH_H */