auth2-pam.c

   1 #include "includes.h"
   2 RCSID("$Id$");
   3
   4 #ifdef USE_PAM
   5 #include "ssh.h"
   6 #include "ssh2.h"
   7 #include "auth.h"
   8 #include "packet.h"
   9 #include "xmalloc.h"
  10 #include "dispatch.h"
  11 #include <security/pam_appl.h>
  12
  13 struct {
  14         int finished, num_received, num_expected;
  15         int *prompts;
  16         struct pam_response *responses;
  17 } context_pam2 = {0, 0, 0, NULL};
  18
  19 static int do_conversation2(int num_msg, const struct pam_message **msg,
  20                             struct pam_response **resp, void *appdata_ptr);
  21
  22 static struct pam_conv
  23 conv2 = {
  24         do_conversation2,
  25         NULL,
  26 };
  27
  28 void input_userauth_info_response_pam(int type, int plen, void *ctxt);
  29
  30 int
  31 auth2_pam(Authctxt *authctxt)
  32 {
  33         int retval = -1;
  34         char *method = "PAM";
  35
  36         if (authctxt->user == NULL)
  37                 fatal("auth2_pam: internal error: no user");
  38
  39         if (authctxt->valid) {
  40                 conv2.appdata_ptr = authctxt;
  41                 pam_set_conv(&conv2);
  42         }
  43
  44         dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,
  45                      &input_userauth_info_response_pam);
  46         retval = (do_pam_authenticate(0) == PAM_SUCCESS);
  47         dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
  48
  49 #if 0           /* ISSUE: No longer valid, but should this still be
  50                         handled?? */
  51         userauth_log(authctxt, retval, method);
  52 #endif
  53         return retval;
  54 }
  55
  56 static int
  57 do_conversation2(int num_msg, const struct pam_message **msg,
  58                  struct pam_response **resp, void *appdata_ptr)
  59 {
  60         int echo = 0, i = 0, j = 0, done = 0;
  61         char *tmp = NULL, *text = NULL;
  62
  63         context_pam2.finished = 0;
  64         context_pam2.num_received = 0;
  65         context_pam2.num_expected = 0;
  66         context_pam2.prompts = xmalloc(sizeof(int) * num_msg);
  67         context_pam2.responses = xmalloc(sizeof(struct pam_response) * num_msg);
  68         memset(context_pam2.responses, 0, sizeof(struct pam_response) * num_msg);
  69
  70         packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
  71         packet_put_cstring("");                         /* Name */
  72         packet_put_cstring("");                         /* Instructions */
  73         packet_put_cstring("");                         /* Language */
  74         for (i = 0, j = 0; i < num_msg; i++) {
  75                 if((PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_ON) ||
  76                    (PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_OFF) ||
  77                    (i == num_msg - 1)) {
  78                         j++;
  79                 }
  80         }
  81         packet_put_int(j);                              /* Number of prompts. */
  82         context_pam2.num_expected = j;
  83         for (i = 0, j = 0; i < num_msg; i++) {
  84                 switch(PAM_MSG_MEMBER(msg, i, msg_style)) {
  85                         case PAM_PROMPT_ECHO_ON:
  86                                 echo = 1;
  87                                 break;
  88                         case PAM_PROMPT_ECHO_OFF:
  89                                 echo = 0;
  90                                 break;
  91                         default:
  92                                 echo = 0;
  93                                 break;
  94                 }
  95                 if(text) {
  96                         tmp = xmalloc(strlen(text) + strlen(PAM_MSG_MEMBER(msg, i, msg)) + 2);
  97                         strcpy(tmp, text);
  98                         strcat(tmp, "\n");
  99                         strcat(tmp, PAM_MSG_MEMBER(msg, i, msg));
 100                         xfree(text);
 101                         text = tmp;
 102                         tmp = NULL;
 103                 } else {
 104                         text = xstrdup(PAM_MSG_MEMBER(msg, i, msg));
 105                 }
 106                 if((PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_ON) ||
 107                    (PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_OFF) ||
 108                    (i == num_msg - 1)) {
 109                         debug("sending prompt ssh-%d(pam-%d) = \"%s\"",
 110                               j, i, text);
 111                         context_pam2.prompts[j++] = i;
 112                         packet_put_cstring(text);
 113                         packet_put_char(echo);
 114                         xfree(text);
 115                         text = NULL;
 116                 }
 117         }
 118         packet_send();
 119         packet_write_wait();
 120
 121         /* Grabbing control of execution and spinning until we get what
 122          * we want is probably rude, but it seems to work properly, and
 123          * the client *should* be in lock-step with us, so the loop should
 124          * only be traversed once. */
 125         while(context_pam2.finished == 0) {
 126                 done = 1;
 127                 dispatch_run(DISPATCH_BLOCK, &done, appdata_ptr);
 128                 if(context_pam2.finished == 0) {
 129                         debug("extra packet during conversation");
 130                 }
 131         }
 132
 133         if(context_pam2.num_received == context_pam2.num_expected) {
 134                 *resp = context_pam2.responses;
 135                 return PAM_SUCCESS;
 136         } else {
 137                 return PAM_CONV_ERR;
 138         }
 139 }
 140
 141 void
 142 input_userauth_info_response_pam(int type, int plen, void *ctxt)
 143 {
 144         Authctxt *authctxt = ctxt;
 145         unsigned int nresp = 0, rlen = 0, i = 0;
 146         char *resp;
 147
 148         if (authctxt == NULL)
 149                 fatal("input_userauth_info_response_pam: no authentication context");
 150
 151         if (authctxt->attempt++ >= AUTH_FAIL_MAX)
 152                 packet_disconnect("too many failed userauth_requests");
 153
 154         nresp = packet_get_int();       /* Number of responses. */
 155         debug("got %d responses", nresp);
 156
 157         for (i = 0; i < nresp; i++) {
 158                 int j = context_pam2.prompts[i];
 159                 resp = packet_get_string(&rlen);
 160                 debug("response ssh-%d(pam-%d) = \"%s\"", i, j, resp);
 161                 context_pam2.responses[j].resp_retcode = PAM_SUCCESS;
 162                 context_pam2.responses[j].resp = xstrdup(resp);
 163                 xfree(resp);
 164                 context_pam2.num_received++;
 165         }
 166
 167         context_pam2.finished = 1;
 168
 169         packet_done();
 170 }
 171
 172 #endif