+/*
+ * "Blind" conversation function for password authentication. Assumes that
+ * echo-off prompts are for the password and stores messages for later
+ * display.
+ */
+static int
+sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
+ struct pam_response **resp, void *data)
+{
+ struct pam_response *reply;
+ int i;
+ size_t len;
+
+ debug3("PAM: %s called with %d messages", __func__, n);
+
+ *resp = NULL;
+
+ if (n <= 0 || n > PAM_MAX_NUM_MSG)
+ return (PAM_CONV_ERR);
+
+ if ((reply = calloc(n, sizeof(*reply))) == NULL)
+ return (PAM_CONV_ERR);
+
+ for (i = 0; i < n; ++i) {
+ switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
+ case PAM_PROMPT_ECHO_OFF:
+ if (sshpam_password == NULL)
+ goto fail;
+ if ((reply[i].resp = strdup(sshpam_password)) == NULL)
+ goto fail;
+ reply[i].resp_retcode = PAM_SUCCESS;
+ break;
+ case PAM_ERROR_MSG:
+ case PAM_TEXT_INFO:
+ len = strlen(PAM_MSG_MEMBER(msg, i, msg));
+ if (len > 0) {
+ buffer_append(&loginmsg,
+ PAM_MSG_MEMBER(msg, i, msg), len);
+ buffer_append(&loginmsg, "\n", 1);
+ }
+ if ((reply[i].resp = strdup("")) == NULL)
+ goto fail;
+ reply[i].resp_retcode = PAM_SUCCESS;
+ break;
+ default:
+ goto fail;
+ }
+ }
+ *resp = reply;
+ return (PAM_SUCCESS);
+
+ fail:
+ for(i = 0; i < n; i++) {
+ if (reply[i].resp != NULL)
+ xfree(reply[i].resp);
+ }
+ xfree(reply);
+ return (PAM_CONV_ERR);
+}
+
+static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
+
+/*
+ * Attempt password authentication via PAM
+ */
+int
+sshpam_auth_passwd(Authctxt *authctxt, const char *password)
+{
+ int flags = (options.permit_empty_passwd == 0 ?
+ PAM_DISALLOW_NULL_AUTHTOK : 0);
+
+ if (!options.use_pam || sshpam_handle == NULL)
+ fatal("PAM: %s called when PAM disabled or failed to "
+ "initialise.", __func__);
+
+ sshpam_password = password;
+ sshpam_authctxt = authctxt;
+
+ /*
+ * If the user logging in is invalid, or is root but is not permitted
+ * by PermitRootLogin, use an invalid password to prevent leaking
+ * information via timing (eg if the PAM config has a delay on fail).
+ */
+ if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
+ options.permit_root_login != PERMIT_YES))
+ sshpam_password = badpw;
+
+ sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+ (const void *)&passwd_conv);
+ if (sshpam_err != PAM_SUCCESS)
+ fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
+ pam_strerror(sshpam_handle, sshpam_err));
+
+ sshpam_err = pam_authenticate(sshpam_handle, flags);
+ sshpam_password = NULL;
+ if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
+ debug("PAM: password authentication accepted for %.100s",
+ authctxt->user);
+ return 1;
+ } else {
+ debug("PAM: password authentication failed for %.100s: %s",
+ authctxt->valid ? authctxt->user : "an illegal user",
+ pam_strerror(sshpam_handle, sshpam_err));
+ return 0;
+ }
+}