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         userauth_log(authctxt, retval, method);
  50
  51         return retval;
  52 }
  53
  54 static int
  55 do_conversation2(int num_msg, const struct pam_message **msg,
  56                  struct pam_response **resp, void *appdata_ptr)
  57 {
  58         int echo = 0, i = 0, j = 0, done = 0;
  59         char *tmp = NULL, *text = NULL;
  60
  61         context_pam2.finished = 0;
  62         context_pam2.num_received = 0;
  63         context_pam2.num_expected = 0;
  64         context_pam2.prompts = xmalloc(sizeof(int) * num_msg);
  65         context_pam2.responses = xmalloc(sizeof(struct pam_response) * num_msg);
  66         memset(context_pam2.responses, 0, sizeof(struct pam_response) * num_msg);
  67
  68         packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
  69         packet_put_cstring("");                         /* Name */
  70         packet_put_cstring("");                         /* Instructions */
  71         packet_put_cstring("");                         /* Language */
  72         for (i = 0, j = 0; i < num_msg; i++) {
  73                 if((PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_ON) ||
  74                    (PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_OFF) ||
  75                    (i == num_msg - 1)) {
  76                         j++;
  77                 }
  78         }
  79         packet_put_int(j);                              /* Number of prompts. */
  80         context_pam2.num_expected = j;
  81         for (i = 0, j = 0; i < num_msg; i++) {
  82                 switch(PAM_MSG_MEMBER(msg, i, msg_style)) {
  83                         case PAM_PROMPT_ECHO_ON:
  84                                 echo = 1;
  85                                 break;
  86                         case PAM_PROMPT_ECHO_OFF:
  87                                 echo = 0;
  88                                 break;
  89                         default:
  90                                 echo = 0;
  91                                 break;
  92                 }
  93                 if(text) {
  94                         tmp = xmalloc(strlen(text) + strlen(PAM_MSG_MEMBER(msg, i, msg)) + 2);
  95                         strcpy(tmp, text);
  96                         strcat(tmp, "\n");
  97                         strcat(tmp, PAM_MSG_MEMBER(msg, i, msg));
  98                         xfree(text);
  99                         text = tmp;
 100                         tmp = NULL;
 101                 } else {
 102                         text = xstrdup(PAM_MSG_MEMBER(msg, i, msg));
 103                 }
 104                 if((PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_ON) ||
 105                    (PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_OFF) ||
 106                    (i == num_msg - 1)) {
 107                         debug("sending prompt ssh-%d(pam-%d) = \"%s\"",
 108                               j, i, text);
 109                         context_pam2.prompts[j++] = i;
 110                         packet_put_cstring(text);
 111                         packet_put_char(echo);
 112                         xfree(text);
 113                         text = NULL;
 114                 }
 115         }
 116         packet_send();
 117         packet_write_wait();
 118
 119         /* Grabbing control of execution and spinning until we get what
 120          * we want is probably rude, but it seems to work properly, and
 121          * the client *should* be in lock-step with us, so the loop should
 122          * only be traversed once. */
 123         while(context_pam2.finished == 0) {
 124                 done = 1;
 125                 dispatch_run(DISPATCH_BLOCK, &done, appdata_ptr);
 126                 if(context_pam2.finished == 0) {
 127                         debug("extra packet during conversation");
 128                 }
 129         }
 130
 131         if(context_pam2.num_received == context_pam2.num_expected) {
 132                 *resp = context_pam2.responses;
 133                 return PAM_SUCCESS;
 134         } else {
 135                 return PAM_CONV_ERR;
 136         }
 137 }
 138
 139 void
 140 input_userauth_info_response_pam(int type, int plen, void *ctxt)
 141 {
 142         Authctxt *authctxt = ctxt;
 143         unsigned int nresp = 0, rlen = 0, i = 0;
 144         char *resp;
 145
 146         if (authctxt == NULL)
 147                 fatal("input_userauth_info_response_pam: no authentication context");
 148
 149         if (authctxt->attempt++ >= AUTH_FAIL_MAX)
 150                 packet_disconnect("too many failed userauth_requests");
 151
 152         nresp = packet_get_int();       /* Number of responses. */
 153         debug("got %d responses", nresp);
 154
 155         for (i = 0; i < nresp; i++) {
 156                 int j = context_pam2.prompts[i];
 157                 resp = packet_get_string(&rlen);
 158                 debug("response ssh-%d(pam-%d) = \"%s\"", i, j, resp);
 159                 context_pam2.responses[j].resp_retcode = PAM_SUCCESS;
 160                 context_pam2.responses[j].resp = xstrdup(resp);
 161                 xfree(resp);
 162                 context_pam2.num_received++;
 163         }
 164
 165         context_pam2.finished = 1;
 166
 167         packet_done();
 168 }
 169
 170 #endif