1 | /* |
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2 | * Copyright (c) 1999 Dug Song. All rights reserved. |
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3 | * |
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4 | * Redistribution and use in source and binary forms, with or without |
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5 | * modification, are permitted provided that the following conditions |
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6 | * are met: |
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7 | * 1. Redistributions of source code must retain the above copyright |
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8 | * notice, this list of conditions and the following disclaimer. |
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9 | * 2. Redistributions in binary form must reproduce the above copyright |
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10 | * notice, this list of conditions and the following disclaimer in the |
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11 | * documentation and/or other materials provided with the distribution. |
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12 | * |
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13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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23 | */ |
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24 | |
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25 | #include "includes.h" |
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26 | RCSID("$OpenBSD: auth-krb4.c,v 1.28 2002/09/26 11:38:43 markus Exp $"); |
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27 | |
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28 | #include "ssh.h" |
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29 | #include "ssh1.h" |
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30 | #include "packet.h" |
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31 | #include "xmalloc.h" |
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32 | #include "log.h" |
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33 | #include "servconf.h" |
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34 | #include "uidswap.h" |
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35 | #include "auth.h" |
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36 | |
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37 | #ifdef AFS |
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38 | #include "radix.h" |
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39 | #endif |
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40 | |
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41 | #ifdef KRB4 |
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42 | extern ServerOptions options; |
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43 | |
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44 | static int |
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45 | krb4_init(void *context) |
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46 | { |
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47 | static int cleanup_registered = 0; |
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48 | Authctxt *authctxt = (Authctxt *)context; |
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49 | const char *tkt_root = TKT_ROOT; |
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50 | struct stat st; |
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51 | int fd; |
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52 | |
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53 | if (!authctxt->krb4_ticket_file) { |
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54 | /* Set unique ticket string manually since we're still root. */ |
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55 | authctxt->krb4_ticket_file = xmalloc(MAXPATHLEN); |
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56 | #ifdef AFS |
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57 | if (lstat("/ticket", &st) != -1) |
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58 | tkt_root = "/ticket/"; |
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59 | #endif /* AFS */ |
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60 | snprintf(authctxt->krb4_ticket_file, MAXPATHLEN, "%s%u_%ld", |
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61 | tkt_root, authctxt->pw->pw_uid, (long)getpid()); |
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62 | krb_set_tkt_string(authctxt->krb4_ticket_file); |
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63 | } |
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64 | /* Register ticket cleanup in case of fatal error. */ |
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65 | if (!cleanup_registered) { |
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66 | fatal_add_cleanup(krb4_cleanup_proc, authctxt); |
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67 | cleanup_registered = 1; |
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68 | } |
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69 | /* Try to create our ticket file. */ |
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70 | if ((fd = mkstemp(authctxt->krb4_ticket_file)) != -1) { |
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71 | close(fd); |
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72 | return (1); |
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73 | } |
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74 | /* Ticket file exists - make sure user owns it (just passed ticket). */ |
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75 | if (lstat(authctxt->krb4_ticket_file, &st) != -1) { |
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76 | if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) && |
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77 | st.st_uid == authctxt->pw->pw_uid) |
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78 | return (1); |
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79 | } |
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80 | /* Failure - cancel cleanup function, leaving ticket for inspection. */ |
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81 | log("WARNING: bad ticket file %s", authctxt->krb4_ticket_file); |
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82 | |
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83 | fatal_remove_cleanup(krb4_cleanup_proc, authctxt); |
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84 | cleanup_registered = 0; |
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85 | |
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86 | xfree(authctxt->krb4_ticket_file); |
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87 | authctxt->krb4_ticket_file = NULL; |
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88 | |
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89 | return (0); |
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90 | } |
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91 | |
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92 | /* |
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93 | * try krb4 authentication, |
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94 | * return 1 on success, 0 on failure, -1 if krb4 is not available |
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95 | */ |
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96 | int |
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97 | auth_krb4_password(Authctxt *authctxt, const char *password) |
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98 | { |
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99 | AUTH_DAT adata; |
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100 | KTEXT_ST tkt; |
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101 | struct hostent *hp; |
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102 | struct passwd *pw; |
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103 | char localhost[MAXHOSTNAMELEN], phost[INST_SZ], realm[REALM_SZ]; |
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104 | u_int32_t faddr; |
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105 | int r; |
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106 | |
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107 | if ((pw = authctxt->pw) == NULL) |
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108 | return (0); |
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109 | |
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110 | /* |
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111 | * Try Kerberos password authentication only for non-root |
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112 | * users and only if Kerberos is installed. |
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113 | */ |
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114 | if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) { |
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115 | /* Set up our ticket file. */ |
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116 | if (!krb4_init(authctxt)) { |
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117 | log("Couldn't initialize Kerberos ticket file for %s!", |
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118 | pw->pw_name); |
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119 | goto failure; |
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120 | } |
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121 | /* Try to get TGT using our password. */ |
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122 | r = krb_get_pw_in_tkt((char *) pw->pw_name, "", realm, |
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123 | "krbtgt", realm, DEFAULT_TKT_LIFE, (char *)password); |
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124 | if (r != INTK_OK) { |
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125 | debug("Kerberos v4 password authentication for %s " |
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126 | "failed: %s", pw->pw_name, krb_err_txt[r]); |
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127 | goto failure; |
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128 | } |
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129 | /* Successful authentication. */ |
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130 | chown(tkt_string(), pw->pw_uid, pw->pw_gid); |
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131 | |
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132 | /* |
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133 | * Now that we have a TGT, try to get a local |
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134 | * "rcmd" ticket to ensure that we are not talking |
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135 | * to a bogus Kerberos server. |
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136 | */ |
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137 | gethostname(localhost, sizeof(localhost)); |
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138 | strlcpy(phost, (char *)krb_get_phost(localhost), |
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139 | sizeof(phost)); |
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140 | r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33); |
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141 | |
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142 | if (r == KSUCCESS) { |
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143 | if ((hp = gethostbyname(localhost)) == NULL) { |
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144 | log("Couldn't get local host address!"); |
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145 | goto failure; |
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146 | } |
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147 | memmove((void *)&faddr, (void *)hp->h_addr, |
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148 | sizeof(faddr)); |
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149 | |
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150 | /* Verify our "rcmd" ticket. */ |
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151 | r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost, |
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152 | faddr, &adata, ""); |
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153 | if (r == RD_AP_UNDEC) { |
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154 | /* |
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155 | * Probably didn't have a srvtab on |
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156 | * localhost. Disallow login. |
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157 | */ |
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158 | log("Kerberos v4 TGT for %s unverifiable, " |
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159 | "no srvtab installed? krb_rd_req: %s", |
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160 | pw->pw_name, krb_err_txt[r]); |
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161 | goto failure; |
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162 | } else if (r != KSUCCESS) { |
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163 | log("Kerberos v4 %s ticket unverifiable: %s", |
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164 | KRB4_SERVICE_NAME, krb_err_txt[r]); |
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165 | goto failure; |
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166 | } |
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167 | } else if (r == KDC_PR_UNKNOWN) { |
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168 | /* |
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169 | * Disallow login if no rcmd service exists, and |
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170 | * log the error. |
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171 | */ |
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172 | log("Kerberos v4 TGT for %s unverifiable: %s; %s.%s " |
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173 | "not registered, or srvtab is wrong?", pw->pw_name, |
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174 | krb_err_txt[r], KRB4_SERVICE_NAME, phost); |
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175 | goto failure; |
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176 | } else { |
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177 | /* |
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178 | * TGT is bad, forget it. Possibly spoofed! |
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179 | */ |
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180 | debug("WARNING: Kerberos v4 TGT possibly spoofed " |
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181 | "for %s: %s", pw->pw_name, krb_err_txt[r]); |
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182 | goto failure; |
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183 | } |
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184 | /* Authentication succeeded. */ |
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185 | return (1); |
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186 | } else |
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187 | /* Logging in as root or no local Kerberos realm. */ |
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188 | debug("Unable to authenticate to Kerberos."); |
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189 | |
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190 | failure: |
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191 | krb4_cleanup_proc(authctxt); |
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192 | |
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193 | if (!options.kerberos_or_local_passwd) |
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194 | return (0); |
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195 | |
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196 | /* Fall back to ordinary passwd authentication. */ |
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197 | return (-1); |
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198 | } |
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199 | |
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200 | void |
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201 | krb4_cleanup_proc(void *context) |
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202 | { |
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203 | Authctxt *authctxt = (Authctxt *)context; |
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204 | debug("krb4_cleanup_proc called"); |
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205 | if (authctxt->krb4_ticket_file) { |
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206 | (void) dest_tkt(); |
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207 | xfree(authctxt->krb4_ticket_file); |
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208 | authctxt->krb4_ticket_file = NULL; |
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209 | } |
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210 | } |
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211 | |
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212 | int |
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213 | auth_krb4(Authctxt *authctxt, KTEXT auth, char **client, KTEXT reply) |
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214 | { |
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215 | AUTH_DAT adat = {0}; |
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216 | Key_schedule schedule; |
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217 | struct sockaddr_in local, foreign; |
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218 | char instance[INST_SZ]; |
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219 | socklen_t slen; |
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220 | u_int cksum; |
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221 | int r, s; |
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222 | |
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223 | s = packet_get_connection_in(); |
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224 | |
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225 | slen = sizeof(local); |
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226 | memset(&local, 0, sizeof(local)); |
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227 | if (getsockname(s, (struct sockaddr *) & local, &slen) < 0) |
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228 | debug("getsockname failed: %.100s", strerror(errno)); |
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229 | slen = sizeof(foreign); |
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230 | memset(&foreign, 0, sizeof(foreign)); |
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231 | if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) { |
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232 | debug("getpeername failed: %.100s", strerror(errno)); |
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233 | fatal_cleanup(); |
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234 | } |
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235 | instance[0] = '*'; |
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236 | instance[1] = 0; |
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237 | |
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238 | /* Get the encrypted request, challenge, and session key. */ |
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239 | if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, |
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240 | 0, &adat, ""))) { |
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241 | debug("Kerberos v4 krb_rd_req: %.100s", krb_err_txt[r]); |
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242 | return (0); |
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243 | } |
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244 | des_key_sched((des_cblock *) adat.session, schedule); |
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245 | |
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246 | *client = xmalloc(MAX_K_NAME_SZ); |
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247 | (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname, |
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248 | *adat.pinst ? "." : "", adat.pinst, adat.prealm); |
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249 | |
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250 | /* Check ~/.klogin authorization now. */ |
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251 | if (kuserok(&adat, authctxt->user) != KSUCCESS) { |
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252 | log("Kerberos v4 .klogin authorization failed for %s to " |
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253 | "account %s", *client, authctxt->user); |
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254 | xfree(*client); |
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255 | *client = NULL; |
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256 | return (0); |
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257 | } |
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258 | /* Increment the checksum, and return it encrypted with the |
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259 | session key. */ |
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260 | cksum = adat.checksum + 1; |
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261 | cksum = htonl(cksum); |
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262 | |
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263 | /* If we can't successfully encrypt the checksum, we send back an |
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264 | empty message, admitting our failure. */ |
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265 | if ((r = krb_mk_priv((u_char *) & cksum, reply->dat, sizeof(cksum) + 1, |
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266 | schedule, &adat.session, &local, &foreign)) < 0) { |
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267 | debug("Kerberos v4 mk_priv: (%d) %s", r, krb_err_txt[r]); |
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268 | reply->dat[0] = 0; |
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269 | reply->length = 0; |
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270 | } else |
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271 | reply->length = r; |
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272 | |
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273 | /* Clear session key. */ |
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274 | memset(&adat.session, 0, sizeof(&adat.session)); |
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275 | return (1); |
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276 | } |
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277 | #endif /* KRB4 */ |
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278 | |
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279 | #ifdef AFS |
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280 | int |
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281 | auth_krb4_tgt(Authctxt *authctxt, const char *string) |
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282 | { |
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283 | CREDENTIALS creds; |
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284 | struct passwd *pw; |
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285 | |
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286 | if ((pw = authctxt->pw) == NULL) |
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287 | goto failure; |
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288 | |
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289 | temporarily_use_uid(pw); |
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290 | |
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291 | if (!radix_to_creds(string, &creds)) { |
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292 | log("Protocol error decoding Kerberos v4 TGT"); |
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293 | goto failure; |
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294 | } |
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295 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ |
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296 | strlcpy(creds.service, "krbtgt", sizeof creds.service); |
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297 | |
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298 | if (strcmp(creds.service, "krbtgt")) { |
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299 | log("Kerberos v4 TGT (%s%s%s@%s) rejected for %s", |
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300 | creds.pname, creds.pinst[0] ? "." : "", creds.pinst, |
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301 | creds.realm, pw->pw_name); |
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302 | goto failure; |
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303 | } |
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304 | if (!krb4_init(authctxt)) |
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305 | goto failure; |
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306 | |
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307 | if (in_tkt(creds.pname, creds.pinst) != KSUCCESS) |
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308 | goto failure; |
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309 | |
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310 | if (save_credentials(creds.service, creds.instance, creds.realm, |
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311 | creds.session, creds.lifetime, creds.kvno, &creds.ticket_st, |
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312 | creds.issue_date) != KSUCCESS) { |
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313 | debug("Kerberos v4 TGT refused: couldn't save credentials"); |
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314 | goto failure; |
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315 | } |
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316 | /* Successful authentication, passed all checks. */ |
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317 | chown(tkt_string(), pw->pw_uid, pw->pw_gid); |
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318 | |
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319 | debug("Kerberos v4 TGT accepted (%s%s%s@%s)", |
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320 | creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm); |
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321 | memset(&creds, 0, sizeof(creds)); |
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322 | |
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323 | restore_uid(); |
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324 | |
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325 | return (1); |
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326 | |
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327 | failure: |
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328 | krb4_cleanup_proc(authctxt); |
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329 | memset(&creds, 0, sizeof(creds)); |
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330 | restore_uid(); |
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331 | |
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332 | return (0); |
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333 | } |
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334 | |
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335 | int |
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336 | auth_afs_token(Authctxt *authctxt, const char *token_string) |
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337 | { |
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338 | CREDENTIALS creds; |
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339 | struct passwd *pw; |
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340 | uid_t uid; |
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341 | |
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342 | if ((pw = authctxt->pw) == NULL) |
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343 | return (0); |
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344 | |
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345 | if (!radix_to_creds(token_string, &creds)) { |
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346 | log("Protocol error decoding AFS token"); |
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347 | return (0); |
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348 | } |
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349 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ |
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350 | strlcpy(creds.service, "afs", sizeof creds.service); |
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351 | |
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352 | if (strncmp(creds.pname, "AFS ID ", 7) == 0) |
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353 | uid = atoi(creds.pname + 7); |
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354 | else |
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355 | uid = pw->pw_uid; |
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356 | |
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357 | if (kafs_settoken(creds.realm, uid, &creds)) { |
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358 | log("AFS token (%s@%s) rejected for %s", |
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359 | creds.pname, creds.realm, pw->pw_name); |
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360 | memset(&creds, 0, sizeof(creds)); |
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361 | return (0); |
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362 | } |
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363 | debug("AFS token accepted (%s@%s)", creds.pname, creds.realm); |
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364 | memset(&creds, 0, sizeof(creds)); |
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365 | |
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366 | return (1); |
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367 | } |
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368 | #endif /* AFS */ |
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