auth2-pam.c

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