1 /* $OpenBSD: auth.h,v 1.100 2019/09/06 05:23:55 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 <bsd_auth.h> 34 #ifdef KRB5 35 #include <krb5.h> 36 #endif 37 38 struct passwd; 39 struct ssh; 40 struct sshbuf; 41 struct sshkey; 42 struct sshauthopt; 43 44 typedef struct Authctxt Authctxt; 45 typedef struct Authmethod Authmethod; 46 typedef struct KbdintDevice KbdintDevice; 47 48 struct Authctxt { 49 sig_atomic_t success; 50 int authenticated; /* authenticated and alarms cancelled */ 51 int postponed; /* authentication needs another step */ 52 int valid; /* user exists and is allowed to login */ 53 int attempt; 54 int failures; 55 int server_caused_failure; 56 int force_pwchange; 57 char *user; /* username sent by the client */ 58 char *service; 59 struct passwd *pw; /* set if 'valid' */ 60 char *style; 61 62 /* Method lists for multiple authentication */ 63 char **auth_methods; /* modified from server config */ 64 u_int num_auth_methods; 65 66 /* Authentication method-specific data */ 67 void *methoddata; 68 void *kbdintctxt; 69 auth_session_t *as; 70 #ifdef KRB5 71 krb5_context krb5_ctx; 72 krb5_ccache krb5_fwd_ccache; 73 krb5_principal krb5_user; 74 char *krb5_ticket_file; 75 #endif 76 77 /* Authentication keys already used; these will be refused henceforth */ 78 struct sshkey **prev_keys; 79 u_int nprev_keys; 80 81 /* Last used key and ancillary information from active auth method */ 82 struct sshkey *auth_method_key; 83 char *auth_method_info; 84 85 /* Information exposed to session */ 86 struct sshbuf *session_info; /* Auth info for environment */ 87 }; 88 89 /* 90 * Every authentication method has to handle authentication requests for 91 * non-existing users, or for users that are not allowed to login. In this 92 * case 'valid' is set to 0, but 'user' points to the username requested by 93 * the client. 94 */ 95 96 struct Authmethod { 97 char *name; 98 int (*userauth)(struct ssh *); 99 int *enabled; 100 }; 101 102 /* 103 * Keyboard interactive device: 104 * init_ctx returns: non NULL upon success 105 * query returns: 0 - success, otherwise failure 106 * respond returns: 0 - success, 1 - need further interaction, 107 * otherwise - failure 108 */ 109 struct KbdintDevice 110 { 111 const char *name; 112 void* (*init_ctx)(Authctxt*); 113 int (*query)(void *ctx, char **name, char **infotxt, 114 u_int *numprompts, char ***prompts, u_int **echo_on); 115 int (*respond)(void *ctx, u_int numresp, char **responses); 116 void (*free_ctx)(void *ctx); 117 }; 118 119 int 120 auth_rhosts2(struct passwd *, const char *, const char *, const char *); 121 122 int auth_password(struct ssh *, const char *); 123 124 int hostbased_key_allowed(struct ssh *, struct passwd *, 125 const char *, char *, struct sshkey *); 126 int user_key_allowed(struct ssh *, struct passwd *, struct sshkey *, int, 127 struct sshauthopt **); 128 int auth2_key_already_used(Authctxt *, const struct sshkey *); 129 130 /* 131 * Handling auth method-specific information for logging and prevention 132 * of key reuse during multiple authentication. 133 */ 134 void auth2_authctxt_reset_info(Authctxt *); 135 void auth2_record_key(Authctxt *, int, const struct sshkey *); 136 void auth2_record_info(Authctxt *authctxt, const char *, ...) 137 __attribute__((__format__ (printf, 2, 3))) 138 __attribute__((__nonnull__ (2))); 139 void auth2_update_session_info(Authctxt *, const char *, const char *); 140 141 #ifdef KRB5 142 int auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *); 143 int auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt); 144 int auth_krb5_password(Authctxt *authctxt, const char *password); 145 void krb5_cleanup_proc(Authctxt *authctxt); 146 #endif /* KRB5 */ 147 148 void do_authentication2(struct ssh *); 149 150 void auth_log(struct ssh *, int, int, const char *, const char *); 151 void auth_maxtries_exceeded(struct ssh *) __attribute__((noreturn)); 152 void userauth_finish(struct ssh *, int, const char *, const char *); 153 int auth_root_allowed(struct ssh *, const char *); 154 155 char *auth2_read_banner(void); 156 int auth2_methods_valid(const char *, int); 157 int auth2_update_methods_lists(Authctxt *, const char *, const char *); 158 int auth2_setup_methods_lists(Authctxt *); 159 int auth2_method_allowed(Authctxt *, const char *, const char *); 160 161 void privsep_challenge_enable(void); 162 163 int auth2_challenge(struct ssh *, char *); 164 void auth2_challenge_stop(struct ssh *); 165 int bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **); 166 int bsdauth_respond(void *, u_int, char **); 167 168 int allowed_user(struct ssh *, struct passwd *); 169 struct passwd * getpwnamallow(struct ssh *, const char *user); 170 171 char *expand_authorized_keys(const char *, struct passwd *pw); 172 char *authorized_principals_file(struct passwd *); 173 174 FILE *auth_openkeyfile(const char *, struct passwd *, int); 175 FILE *auth_openprincipals(const char *, struct passwd *, int); 176 int auth_key_is_revoked(struct sshkey *); 177 178 const char *auth_get_canonical_hostname(struct ssh *, int); 179 180 HostStatus 181 check_key_in_hostfiles(struct passwd *, struct sshkey *, const char *, 182 const char *, const char *); 183 184 /* hostkey handling */ 185 struct sshkey *get_hostkey_by_index(int); 186 struct sshkey *get_hostkey_public_by_index(int, struct ssh *); 187 struct sshkey *get_hostkey_public_by_type(int, int, struct ssh *); 188 struct sshkey *get_hostkey_private_by_type(int, int, struct ssh *); 189 int get_hostkey_index(struct sshkey *, int, struct ssh *); 190 int sshd_hostkey_sign(struct ssh *, struct sshkey *, struct sshkey *, 191 u_char **, size_t *, const u_char *, size_t, const char *); 192 193 /* Key / cert options linkage to auth layer */ 194 const struct sshauthopt *auth_options(struct ssh *); 195 int auth_activate_options(struct ssh *, struct sshauthopt *); 196 void auth_restrict_session(struct ssh *); 197 int auth_authorise_keyopts(struct ssh *, struct passwd *pw, 198 struct sshauthopt *, int, const char *); 199 void auth_log_authopts(const char *, const struct sshauthopt *, int); 200 201 /* debug messages during authentication */ 202 void auth_debug_add(const char *fmt,...) 203 __attribute__((format(printf, 1, 2))); 204 void auth_debug_send(struct ssh *); 205 void auth_debug_reset(void); 206 207 struct passwd *fakepw(void); 208 209 #define SSH_SUBPROCESS_STDOUT_DISCARD (1) /* Discard stdout */ 210 #define SSH_SUBPROCESS_STDOUT_CAPTURE (1<<1) /* Redirect stdout */ 211 #define SSH_SUBPROCESS_STDERR_DISCARD (1<<2) /* Discard stderr */ 212 pid_t subprocess(const char *, struct passwd *, 213 const char *, int, char **, FILE **, u_int flags); 214 215 #endif 216