UTIL: exit() the forked process if exec()-ing a child process fails

When exec() fails, we should not attempt to continue, but just kill the
forked process. The patch adds this logic to the exec_child() and
exec_child_ex() functions to avoid code duplication

Resolves:
https://fedorahosted.org/sssd/ticket/3016

Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

5 files changed, 33 insertions, 37 deletions

diff --git a/src/providers/ad/ad_gpo.c b/src/providers/ad/ad_gpo.c
index 22ac80337..ec2ae2883 100644
--- a/src/providers/ad/ad_gpo.c
+++ b/src/providers/ad/ad_gpo.c
@@ -4189,13 +4189,13 @@ gpo_fork_child(struct tevent_req *req)
     pid = fork();
 
     if (pid == 0) { /* child */
-        err = exec_child_ex(state,
-                            pipefd_to_child, pipefd_from_child,
-                            GPO_CHILD, gpo_child_debug_fd, NULL, false,
-                            STDIN_FILENO, AD_GPO_CHILD_OUT_FILENO);
-        DEBUG(SSSDBG_CRIT_FAILURE, "Could not exec gpo_child: [%d][%s].\n",
-              err, strerror(err));
-        return err;
+        exec_child_ex(state,
+                      pipefd_to_child, pipefd_from_child,
+                      GPO_CHILD, gpo_child_debug_fd, NULL, false,
+                      STDIN_FILENO, AD_GPO_CHILD_OUT_FILENO);
+
+        /* We should never get here */
+        DEBUG(SSSDBG_CRIT_FAILURE, "BUG: Could not exec gpo_child:\n");
     } else if (pid > 0) { /* parent */
         state->child_pid = pid;
         state->io->read_from_child_fd = pipefd_from_child[0];
diff --git a/src/providers/ad/ad_machine_pw_renewal.c b/src/providers/ad/ad_machine_pw_renewal.c
index 7997fbb0c..3d79aa0a6 100644
--- a/src/providers/ad/ad_machine_pw_renewal.c
+++ b/src/providers/ad/ad_machine_pw_renewal.c
@@ -174,15 +174,13 @@ ad_machine_account_password_renewal_send(TALLOC_CTX *mem_ctx,
 
     child_pid = fork();
     if (child_pid == 0) { /* child */
-        ret = exec_child_ex(state, pipefd_to_child, pipefd_from_child,
-                            renewal_data->prog_path, -1,
-                            extra_args, true,
-                            STDIN_FILENO, STDERR_FILENO);
-        if (ret != EOK) {
-            DEBUG(SSSDBG_CRIT_FAILURE, "Could not exec renewal child: [%d][%s].\n",
-                                       ret, strerror(ret));
-            goto done;
-        }
+        exec_child_ex(state, pipefd_to_child, pipefd_from_child,
+                      renewal_data->prog_path, -1,
+                      extra_args, true,
+                      STDIN_FILENO, STDERR_FILENO);
+
+        /* We should never get here */
+        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];
diff --git a/src/providers/ipa/ipa_selinux.c b/src/providers/ipa/ipa_selinux.c
index 3e9efee32..c546d3a99 100644
--- a/src/providers/ipa/ipa_selinux.c
+++ b/src/providers/ipa/ipa_selinux.c
@@ -1047,12 +1047,12 @@ static errno_t selinux_fork_child(struct selinux_child_state *state)
     pid = fork();
 
     if (pid == 0) { /* child */
-        ret = exec_child(state,
-                         pipefd_to_child, pipefd_from_child,
-                         SELINUX_CHILD, selinux_child_debug_fd);
-        DEBUG(SSSDBG_CRIT_FAILURE, "Could not exec selinux_child: [%d][%s].\n",
-              ret, sss_strerror(ret));
-        return ret;
+        exec_child(state,
+                   pipefd_to_child, pipefd_from_child,
+                   SELINUX_CHILD, selinux_child_debug_fd);
+
+        /* We should never get here */
+        DEBUG(SSSDBG_CRIT_FAILURE, "BUG: Could not exec selinux_child\n");
     } else if (pid > 0) { /* parent */
         state->io->read_from_child_fd = pipefd_from_child[0];
         close(pipefd_from_child[1]);
diff --git a/src/providers/krb5/krb5_child_handler.c b/src/providers/krb5/krb5_child_handler.c
index 167a2b2ad..1ca74fcd7 100644
--- a/src/providers/krb5/krb5_child_handler.c
+++ b/src/providers/krb5/krb5_child_handler.c
@@ -309,15 +309,13 @@ static errno_t fork_child(struct tevent_req *req)
     pid = fork();
 
     if (pid == 0) { /* child */
-        err = exec_child_ex(state,
-                            pipefd_to_child, pipefd_from_child,
-                            KRB5_CHILD, state->kr->krb5_ctx->child_debug_fd,
-                            k5c_extra_args, false, STDIN_FILENO, STDOUT_FILENO);
-        if (err != EOK) {
-            DEBUG(SSSDBG_CRIT_FAILURE, "Could not exec KRB5 child: [%d][%s].\n",
-                      err, strerror(err));
-            return err;
-        }
+        exec_child_ex(state,
+                      pipefd_to_child, pipefd_from_child,
+                      KRB5_CHILD, state->kr->krb5_ctx->child_debug_fd,
+                      k5c_extra_args, false, STDIN_FILENO, STDOUT_FILENO);
+
+        /* We should never get here */
+        DEBUG(SSSDBG_CRIT_FAILURE, "BUG: Could not exec KRB5 child\n");
     } else if (pid > 0) { /* parent */
         state->child_pid = pid;
         state->io->read_from_child_fd = pipefd_from_child[0];
diff --git a/src/providers/ldap/sdap_child_helpers.c b/src/providers/ldap/sdap_child_helpers.c
index 90330f13f..69b470dbf 100644
--- a/src/providers/ldap/sdap_child_helpers.c
+++ b/src/providers/ldap/sdap_child_helpers.c
@@ -96,12 +96,12 @@ static errno_t sdap_fork_child(struct tevent_context *ev,
     pid = fork();
 
     if (pid == 0) { /* child */
-        err = exec_child(child,
-                         pipefd_to_child, pipefd_from_child,
-                         LDAP_CHILD, ldap_child_debug_fd);
-        DEBUG(SSSDBG_CRIT_FAILURE, "Could not exec LDAP child: [%d][%s].\n",
-                                    err, strerror(err));
-        return err;
+        exec_child(child,
+                   pipefd_to_child, pipefd_from_child,
+                   LDAP_CHILD, ldap_child_debug_fd);
+
+        /* We should never get here */
+        DEBUG(SSSDBG_CRIT_FAILURE, "BUG: Could not exec LDAP child\n");
     } else if (pid > 0) { /* parent */
         child->pid = pid;
         child->io->read_from_child_fd = pipefd_from_child[0];