AD: Do not leak file descriptors during machine password renewal

Resolves:
    https://fedorahosted.org/sssd/ticket/3017

The AD renewal task was opening a pipe to write to the child process but
never closed it, leaking the fd. This patch uses a desctructor we
already use for pipes towards other child processes.

Reviewed-by: Petr Cech <pcech@redhat.com>

1 files changed, 15 insertions, 13 deletions

diff --git a/src/providers/ad/ad_machine_pw_renewal.c b/src/providers/ad/ad_machine_pw_renewal.c
index b0d2cf64a..205e623e0 100644
--- a/src/providers/ad/ad_machine_pw_renewal.c
+++ b/src/providers/ad/ad_machine_pw_renewal.c
@@ -101,8 +101,7 @@ struct renewal_state {
     struct tevent_timer *timeout_handler;
     struct tevent_context *ev;
 
-    int write_to_child_fd;
-    int read_from_child_fd;
+    struct child_io_fds *io;
 };
 
 static void ad_machine_account_password_renewal_done(struct tevent_req *subreq);
@@ -140,8 +139,15 @@ ad_machine_account_password_renewal_send(TALLOC_CTX *mem_ctx,
 
     state->ev = ev;
     state->child_status = EFAULT;
-    state->read_from_child_fd = -1;
-    state->write_to_child_fd = -1;
+    state->io = talloc(state, struct child_io_fds);
+    if (state->io == NULL) {
+        DEBUG(SSSDBG_CRIT_FAILURE, "talloc failed.\n");
+        ret = ENOMEM;
+        goto done;
+    }
+    state->io->write_to_child_fd = -1;
+    state->io->read_from_child_fd = -1;
+    talloc_set_destructor((void *) state->io, child_io_destructor);
 
     server_name = be_fo_get_active_server_name(be_ctx, AD_SERVICE_NAME);
     talloc_zfree(renewal_data->extra_args[0]);
@@ -183,13 +189,13 @@ ad_machine_account_password_renewal_send(TALLOC_CTX *mem_ctx,
         DEBUG(SSSDBG_CRIT_FAILURE, "Could not exec renewal child\n");
     } else if (child_pid > 0) { /* parent */
 
-        state->read_from_child_fd = pipefd_from_child[0];
+        state->io->read_from_child_fd = pipefd_from_child[0];
         close(pipefd_from_child[1]);
-        sss_fd_nonblocking(state->read_from_child_fd);
+        sss_fd_nonblocking(state->io->read_from_child_fd);
 
-        state->write_to_child_fd = pipefd_to_child[1];
+        state->io->write_to_child_fd = pipefd_to_child[1];
         close(pipefd_to_child[0]);
-        sss_fd_nonblocking(state->write_to_child_fd);
+        sss_fd_nonblocking(state->io->write_to_child_fd);
 
         /* Set up SIGCHLD handler */
         ret = child_handler_setup(ev, child_pid, NULL, NULL, &state->child_ctx);
@@ -210,7 +216,7 @@ ad_machine_account_password_renewal_send(TALLOC_CTX *mem_ctx,
             goto done;
         }
 
-        subreq = read_pipe_send(state, ev, state->read_from_child_fd);
+        subreq = read_pipe_send(state, ev, state->io->read_from_child_fd);
         if (subreq == NULL) {
             DEBUG(SSSDBG_OP_FAILURE, "read_pipe_send failed.\n");
             ret = ERR_RENEWAL_CHILD;
@@ -262,10 +268,6 @@ static void ad_machine_account_password_renewal_done(struct tevent_req *subreq)
                              "---adcli output end---\n",
                              (int) buf_len, buf);
 
-    close(state->read_from_child_fd);
-    state->read_from_child_fd = -1;
-
-
     tevent_req_done(req);
     return;
 }