citadel/auth.c

   1 /*
   2  * $Id$
   3  *
   4  * system-level password checking for host auth mode
   5  * by Nathan Bryant, March 1999
   6  * updated by Trey van Riper, June 2005
   7  *
   8  */
   9
  10 #if defined(__linux) || defined(__sun) /* needed for crypt(): */
  11 #define _XOPEN_SOURCE
  12 #define _XOPEN_SOURCE_EXTENDED 1
  13 #endif
  14
  15 #include <pwd.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <unistd.h>
  19 #include <sys/types.h>
  20
  21 #include "auth.h"
  22 #include "sysdep.h"
  23
  24 #ifdef HAVE_GETSPNAM
  25 #include <shadow.h>
  26 #endif
  27
  28 #ifdef HAVE_PAM_START
  29 #include <security/pam_appl.h>
  30
  31 /*
  32  * struct appdata: passed to the conversation function
  33  */
  34
  35 struct appdata
  36 {
  37   const char *name;
  38   const char *pw;
  39 };
  40
  41 /*
  42  * conv(): the PAM conversation function. this assumes that a
  43  * PAM_PROMPT_ECHO_ON is asking for a username, and a PAM_PROMPT_ECHO_OFF is
  44  * asking for a password. esoteric authentication modules will fail with this
  45  * code, but we can't really support them with the existing client protocol
  46  * anyway. the failure mode should be to deny access, in any case.
  47  */
  48
  49 static int conv(int num_msg, const struct pam_message **msg,
  50                 struct pam_response **resp, void *appdata_ptr)
  51 {
  52   struct pam_response *temp_resp;
  53   struct appdata *data = appdata_ptr;
  54
  55   if ((temp_resp = malloc(sizeof(struct pam_response[num_msg]))) == NULL)
  56     return PAM_CONV_ERR;
  57
  58   while (num_msg--)
  59     {
  60       switch ((*msg)[num_msg].msg_style)
  61         {
  62         case PAM_PROMPT_ECHO_ON:
  63           temp_resp[num_msg].resp = strdup(data->name);
  64           break;
  65         case PAM_PROMPT_ECHO_OFF:
  66           temp_resp[num_msg].resp = strdup(data->pw);
  67           break;
  68         default:
  69           temp_resp[num_msg].resp = NULL;
  70         }
  71       temp_resp[num_msg].resp_retcode = 0;
  72     }
  73
  74   *resp = temp_resp;
  75   return PAM_SUCCESS;
  76 }
  77 #endif /* HAVE_PAM_START */
  78
  79
  80 /*
  81  * check that `pass' is the correct password for `uid'
  82  * returns zero if no, nonzero if yes
  83  */
  84
  85 int validate_password(uid_t uid, const char *pass)
  86 {
  87 #ifdef HAVE_PAM_START
  88         struct pam_conv pc;
  89         struct appdata data;
  90         pam_handle_t *ph;
  91         int i;
  92 #else
  93         char *crypted_pwd;
  94 #ifdef HAVE_GETSPNAM
  95         struct spwd *sp;
  96 #endif
  97 #endif
  98         struct passwd *pw;
  99         int retval = 0;
 100         int flags = 0;
 101
 102         flags = 0;      /* silences compiler warning */
 103
 104 #ifdef PAM_DATA_SILENT
 105         flags = ( flags | PAM_DATA_SILENT ) ;
 106 #endif /* PAM_DATA_SILENT */
 107         if ((pw = getpwuid(uid)) == NULL) {
 108                 return retval;
 109         }
 110
 111 #ifdef HAVE_PAM_START
 112         pc.conv = conv;
 113         pc.appdata_ptr = &data;
 114         data.name = pw->pw_name;
 115         data.pw = pass;
 116         if (pam_start("citadel", pw->pw_name, &pc, &ph) != PAM_SUCCESS)
 117                 return retval;
 118
 119         if ((i = pam_authenticate(ph, flags)) == PAM_SUCCESS)
 120                 if ((i = pam_acct_mgmt(ph, flags)) == PAM_SUCCESS)
 121                         retval = -1;
 122
 123         pam_end(ph, i | flags);
 124 #else
 125         crypted_pwd = pw->pw_passwd;
 126
 127 #ifdef HAVE_GETSPNAM
 128         if ((sp = getspnam(pw->pw_name)) != NULL)
 129                 crypted_pwd = sp->sp_pwdp;
 130 #endif
 131
 132         if (!strcmp(crypt(pass, crypted_pwd), crypted_pwd))
 133                 retval = -1;
 134 #endif                          /* HAVE_PAM_START */
 135
 136         return retval;
 137 }
 138