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 #include <bsd_auth.h> 35 #ifdef KRB5 36 #include <krb5.h> 37 #endif 38 39 struct passwd; 40 struct ssh; 41 struct sshbuf; 42 struct sshkey; 43 struct sshkey_cert; 44 struct sshauthopt; 45 46 typedef struct Authctxt Authctxt; 47 typedef struct Authmethod Authmethod; 48 typedef struct KbdintDevice KbdintDevice; 49 50 struct 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 98 struct Authmethod { 99 char *name; 100 char *synonym; 101 int (*userauth)(struct ssh *, const char *); 102 int *enabled; 103 }; 104 105 /* 106 * Keyboard interactive device: 107 * init_ctx returns: non NULL upon success 108 * query returns: 0 - success, otherwise failure 109 * respond returns: 0 - success, 1 - need further interaction, 110 * otherwise - failure 111 */ 112 struct KbdintDevice 113 { 114 const char *name; 115 void* (*init_ctx)(Authctxt*); 116 int (*query)(void *ctx, char **name, char **infotxt, 117 u_int *numprompts, char ***prompts, u_int **echo_on); 118 int (*respond)(void *ctx, u_int numresp, char **responses); 119 void (*free_ctx)(void *ctx); 120 }; 121 122 int 123 auth_rhosts2(struct passwd *, const char *, const char *, const char *); 124 125 int auth_password(struct ssh *, const char *); 126 127 int hostbased_key_allowed(struct ssh *, struct passwd *, 128 const char *, char *, struct sshkey *); 129 int user_key_allowed(struct ssh *ssh, struct passwd *, struct sshkey *, 130 int, struct sshauthopt **); 131 int auth2_key_already_used(Authctxt *, const struct sshkey *); 132 133 /* 134 * Handling auth method-specific information for logging and prevention 135 * of key reuse during multiple authentication. 136 */ 137 void auth2_authctxt_reset_info(Authctxt *); 138 void auth2_record_key(Authctxt *, int, const struct sshkey *); 139 void auth2_record_info(Authctxt *authctxt, const char *, ...) 140 __attribute__((__format__ (printf, 2, 3))) 141 __attribute__((__nonnull__ (2))); 142 void auth2_update_session_info(Authctxt *, const char *, const char *); 143 144 #ifdef KRB5 145 int auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *); 146 int auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt); 147 int auth_krb5_password(Authctxt *authctxt, const char *password); 148 void krb5_cleanup_proc(Authctxt *authctxt); 149 #endif /* KRB5 */ 150 151 void do_authentication2(struct ssh *); 152 153 void auth_log(struct ssh *, int, int, const char *, const char *); 154 void auth_maxtries_exceeded(struct ssh *) __attribute__((noreturn)); 155 void userauth_finish(struct ssh *, int, const char *, const char *); 156 int auth_root_allowed(struct ssh *, const char *); 157 158 char *auth2_read_banner(void); 159 int auth2_methods_valid(const char *, int); 160 int auth2_update_methods_lists(Authctxt *, const char *, const char *); 161 int auth2_setup_methods_lists(Authctxt *); 162 int auth2_method_allowed(Authctxt *, const char *, const char *); 163 164 void privsep_challenge_enable(void); 165 166 int auth2_challenge(struct ssh *, char *); 167 void auth2_challenge_stop(struct ssh *); 168 int bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **); 169 int bsdauth_respond(void *, u_int, char **); 170 171 int allowed_user(struct ssh *, struct passwd *); 172 struct passwd * getpwnamallow(struct ssh *, const char *user); 173 174 char *expand_authorized_keys(const char *, struct passwd *pw); 175 char *authorized_principals_file(struct passwd *); 176 177 int auth_key_is_revoked(struct sshkey *); 178 179 const char *auth_get_canonical_hostname(struct ssh *, int); 180 181 HostStatus 182 check_key_in_hostfiles(struct passwd *, struct sshkey *, const char *, 183 const char *, const char *); 184 185 /* hostkey handling */ 186 struct sshkey *get_hostkey_by_index(int); 187 struct sshkey *get_hostkey_public_by_index(int, struct ssh *); 188 struct sshkey *get_hostkey_public_by_type(int, int, struct ssh *); 189 struct sshkey *get_hostkey_private_by_type(int, int, struct ssh *); 190 int get_hostkey_index(struct sshkey *, int, struct ssh *); 191 int 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 */ 195 const struct sshauthopt *auth_options(struct ssh *); 196 int auth_activate_options(struct ssh *, struct sshauthopt *); 197 void auth_restrict_session(struct ssh *); 198 void auth_log_authopts(const char *, const struct sshauthopt *, int); 199 200 /* debug messages during authentication */ 201 void auth_debug_add(const char *fmt,...) 202 __attribute__((format(printf, 1, 2))); 203 void auth_debug_send(struct ssh *); 204 void auth_debug_reset(void); 205 206 struct passwd *fakepw(void); 207 208 /* auth2-pubkeyfile.c */ 209 int auth_authorise_keyopts(struct passwd *, struct sshauthopt *, int, 210 const char *, const char *, const char *); 211 int auth_check_principals_line(char *, const struct sshkey_cert *, 212 const char *, struct sshauthopt **); 213 int auth_process_principals(FILE *, const char *, 214 const struct sshkey_cert *, struct sshauthopt **); 215 int auth_check_authkey_line(struct passwd *, struct sshkey *, 216 char *, const char *, const char *, const char *, struct sshauthopt **); 217 int auth_check_authkeys_file(struct passwd *, FILE *, char *, 218 struct sshkey *, const char *, const char *, struct sshauthopt **); 219 FILE *auth_openkeyfile(const char *, struct passwd *, int); 220 FILE *auth_openprincipals(const char *, struct passwd *, int); 221 222 #endif 223