fix for pam proxy chauthtok

When a user from a domain served by the proxy backend changes his
password with passwd the passwd command asks for the old password,
but it is not validated by the pam_chauthtok call in the proxy
backend, because it is running as root.

If the request is coming the unpriviledged socket we now call
pam_authenticate explicitly before pam_chauthtok.

3 files changed, 21 insertions, 9 deletions

diff --git a/server/providers/data_provider.h b/server/providers/data_provider.h
index 2c828fab..9278e396 100644
--- a/server/providers/data_provider.h
+++ b/server/providers/data_provider.h
@@ -115,6 +115,7 @@ struct pam_data {
     struct response_data *resp_list;
 
     bool offline_auth;
+    int priv;
 };
 
 void pam_print_data(int l, struct pam_data *pd);
diff --git a/server/providers/dp_auth_util.c b/server/providers/dp_auth_util.c
index 99e57e2e..630dafe8 100644
--- a/server/providers/dp_auth_util.c
+++ b/server/providers/dp_auth_util.c
@@ -34,6 +34,7 @@ void pam_print_data(int l, struct pam_data *pd)
     DEBUG(l, ("authtok size: %d\n", pd->authtok_size));
     DEBUG(l, ("newauthtok type: %d\n", pd->newauthtok_type));
     DEBUG(l, ("newauthtok size: %d\n", pd->newauthtok_size));
+    DEBUG(l, ("priv: %d\n", pd->priv));
 }
 
 int pam_add_response(struct pam_data *pd, enum response_type type,
@@ -74,6 +75,7 @@ bool dp_pack_pam_request(DBusMessage *msg, struct pam_data *pd)
                                    DBUS_TYPE_ARRAY, DBUS_TYPE_BYTE,
                                        &(pd->newauthtok),
                                        pd->newauthtok_size,
+                                   DBUS_TYPE_INT32, &(pd->priv),
                                    DBUS_TYPE_INVALID);
 
     return ret;
@@ -99,6 +101,7 @@ bool dp_unpack_pam_request(DBusMessage *msg, struct pam_data *pd, DBusError *dbu
                                 DBUS_TYPE_ARRAY, DBUS_TYPE_BYTE,
                                     &(pd->newauthtok),
                                     &(pd->newauthtok_size),
+                                DBUS_TYPE_INT32, &(pd->priv),
                                 DBUS_TYPE_INVALID);
 
     return ret;
diff --git a/server/providers/proxy.c b/server/providers/proxy.c
index 907f044e..0fea89df 100644
--- a/server/providers/proxy.c
+++ b/server/providers/proxy.c
@@ -66,8 +66,8 @@ struct proxy_auth_ctx {
 };
 
 struct authtok_conv {
-    char *authtok;
-    char *oldauthtok;
+    uint32_t authtok_size;
+    uint8_t *authtok;
 };
 
 static int proxy_internal_conv(int num_msg, const struct pam_message **msgm,
@@ -90,7 +90,11 @@ static int proxy_internal_conv(int num_msg, const struct pam_message **msgm,
             case PAM_PROMPT_ECHO_OFF:
                 DEBUG(4, ("Conversation message: [%s]\n", msgm[i]->msg));
                 reply[i].resp_retcode = 0;
-                reply[i].resp = strdup(auth_data->authtok);
+                reply[i].resp = calloc(auth_data->authtok_size + 1,
+                                       sizeof(char));
+                if (reply[i].resp == NULL) goto failed;
+                memcpy(reply[i].resp, auth_data->authtok, auth_data->authtok_size);
+
                 break;
             default:
                 DEBUG(1, ("Conversation style %d not supported.\n",
@@ -142,9 +146,8 @@ static void proxy_pam_handler(struct be_req *req) {
         }
         switch (pd->cmd) {
             case SSS_PAM_AUTHENTICATE:
-/* FIXME: \0 missing at the end */
-                auth_data->authtok=(char *) pd->authtok;
-                auth_data->oldauthtok=NULL;
+                auth_data->authtok_size = pd->authtok_size;
+                auth_data->authtok = pd->authtok;
                 pam_status=pam_authenticate(pamh, 0);
                 break;
             case SSS_PAM_SETCRED:
@@ -160,9 +163,14 @@ static void proxy_pam_handler(struct be_req *req) {
                 pam_status=pam_close_session(pamh, 0);
                 break;
             case SSS_PAM_CHAUTHTOK:
-/* FIXME: \0 missing at the end */
-                auth_data->authtok=(char *) pd->newauthtok;
-                auth_data->oldauthtok=(char *) pd->authtok;
+                if (pd->priv != 1) {
+                    auth_data->authtok_size = pd->authtok_size;
+                    auth_data->authtok = pd->authtok;
+                    pam_status=pam_authenticate(pamh, 0);
+                    if (pam_status != PAM_SUCCESS) break;
+                }
+                auth_data->authtok_size = pd->newauthtok_size;
+                auth_data->authtok = pd->newauthtok;
                 pam_status=pam_chauthtok(pamh, 0);
                 break;
             default: