Move the chroot call to probe_worker

We have discovered a problem when testing offline mode in the symlink
probe. When the probe main function needs to be executed multiple times,
function `probe_common_main`, where the chroot is entered, is called
only once, but function `probe_worker`, which leaves the chroot, is called
many times. This leads to a situation that the first OVAL test is
evaluated in chroot, but all further tests have retrieved data from the
host. Therefore the collected data were wrong. We try to address this
problem by moving the code.

Author: jan-cerny

src/OVAL/probes/probe/probe_main.c

@@ -130,22 +130,6 @@ static int probe_opthandler_rcache(int option, int op, va_list args)
 	return (0);
 }
 
-// Dummy pthread routine
-static void * dummy_routine(void *dummy_param)
-{
-	return NULL;
-}
-
-static void preload_libraries_before_chroot()
-{
-	// Force to load dynamic libraries used by pthread_cancel
-	pthread_t t;
-	if (pthread_create(&t, NULL, dummy_routine, NULL))
-		fail(errno, "pthread_create(probe_preload)", __LINE__ - 1);
-	pthread_cancel(t);
-	pthread_join(t, NULL);
-}
-
 static void probe_common_main_cleanup(void *arg)
 {
 	dD("probe_common_main_cleanup started");
@@ -183,7 +167,6 @@ void *probe_common_main(void *arg)
 {
 	pthread_attr_t th_attr;
 	probe_t        probe;
-	char *rootdir = NULL;
 	struct probe_common_main_argument *probe_argument = (struct probe_common_main_argument *) arg;
 	sch_queuedata_t *data = probe_argument->queuedata;
 	oval_subtype_t subtype = probe_argument->subtype;
@@ -250,52 +233,6 @@ void *probe_common_main(void *arg)
 	OSCAP_GSYM(probe_optdef) = probe.option;
 	OSCAP_GSYM(probe_optdef_count) = probe.optcnt;
 
-#ifndef OS_WINDOWS
-	probe_offline_mode_function_t offline_mode_function = probe_table_get_offline_mode_function(probe.subtype);
-	if (offline_mode_function != NULL) {
-		probe.supported_offline_mode = offline_mode_function();
-	}
-
-	/*
-	 * Setup offline mode(s)
-	 */
-	rootdir = getenv("OSCAP_PROBE_ROOT");
-	if ((rootdir != NULL) && (strlen(rootdir) > 0)) {
-		probe.offline_mode = true;
-
-		preload_libraries_before_chroot(); // todo - maybe useless for own mode
-
-		if (probe.supported_offline_mode & PROBE_OFFLINE_OWN) {
-			dI("Swiching probe to PROBE_OFFLINE_OWN mode.");
-			probe.selected_offline_mode = PROBE_OFFLINE_OWN;
-
-		} else if (probe.supported_offline_mode & PROBE_OFFLINE_CHROOT) {
-			probe.real_root_fd = open("/", O_RDONLY);
-			probe.real_cwd_fd = open(".", O_RDONLY);
-			if (chdir(rootdir) != 0) {
-				fail(errno, "chdir", __LINE__ -1);
-			}
-
-			if (chroot(rootdir) != 0) {
-				fail(errno, "chroot", __LINE__ - 1);
-			}
-			/* NOTE: We're running in a different root directory.
-			 * Unless /proc, /sys are somehow emulated for the new
-			 * environment, they are not relevant and so are other
-			 * runtime only things (e.g. getenv, uname, ...).
-			 * Switch to offline mode. We may add a separate
-			 * mechanism to control this behaviour in the future.
-			 */
-			dI("Swiching probe to PROBE_OFFLINE_CHROOT mode.");
-			probe.selected_offline_mode = PROBE_OFFLINE_CHROOT;
-		}
-	}
-
-	if (getenv("OSCAP_PROBE_RPMDB_PATH") != NULL) {
-		dI("Swiching probe to PROBE_OFFLINE_RPMDB mode.");
-		probe.selected_offline_mode = PROBE_OFFLINE_RPMDB;
-	}
-#endif
 
 	/*
 	 * Create input handler (detached)

src/OVAL/probes/probe/worker.c

@@ -25,6 +25,8 @@
 #endif
 
 #include "_seap.h"
+#include <stdio.h>
+#include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
 #include <pthread.h>
@@ -41,6 +43,29 @@
 extern bool  OSCAP_GSYM(varref_handling);
 extern void *OSCAP_GSYM(probe_arg);
 
+
+static int fail(int err, const char *who, int line)
+{
+	fprintf(stderr, "FAIL: %d:%s: %d, %s\n", line, who, err, strerror(err));
+	exit(err);
+}
+
+// Dummy pthread routine
+static void *dummy_routine(void *dummy_param)
+{
+	return NULL;
+}
+
+static void preload_libraries_before_chroot()
+{
+	// Force to load dynamic libraries used by pthread_cancel
+	pthread_t t;
+	if (pthread_create(&t, NULL, dummy_routine, NULL))
+		fail(errno, "pthread_create(probe_preload)", __LINE__ - 1);
+	pthread_cancel(t);
+	pthread_join(t, NULL);
+}
+
 void *probe_worker_runfn(void *arg)
 {
 	dD("probe_worker_runfn has started");
@@ -945,6 +970,54 @@ static SEXP_t *probe_set_eval(probe_t *probe, SEXP_t *set, size_t depth)
  */
 SEXP_t *probe_worker(probe_t *probe, SEAP_msg_t *msg_in, int *ret)
 {
+#ifndef OS_WINDOWS
+	char *rootdir = NULL;
+	probe_offline_mode_function_t offline_mode_function = probe_table_get_offline_mode_function(probe->subtype);
+	if (offline_mode_function != NULL) {
+		probe->supported_offline_mode = offline_mode_function();
+	}
+
+	/*
+	 * Setup offline mode(s)
+	 */
+	rootdir = getenv("OSCAP_PROBE_ROOT");
+	if ((rootdir != NULL) && (strlen(rootdir) > 0)) {
+		probe->offline_mode = true;
+
+		preload_libraries_before_chroot(); // todo - maybe useless for own mode
+
+		if (probe->supported_offline_mode & PROBE_OFFLINE_OWN) {
+			dI("Switching probe to PROBE_OFFLINE_OWN mode.");
+			probe->selected_offline_mode = PROBE_OFFLINE_OWN;
+
+		} else if (probe->supported_offline_mode & PROBE_OFFLINE_CHROOT) {
+			probe->real_root_fd = open("/", O_RDONLY);
+			probe->real_cwd_fd = open(".", O_RDONLY);
+			if (chdir(rootdir) != 0) {
+				fail(errno, "chdir", __LINE__ -1);
+			}
+
+			if (chroot(rootdir) != 0) {
+				fail(errno, "chroot", __LINE__ - 1);
+			}
+			/* NOTE: We're running in a different root directory.
+			 * Unless /proc, /sys are somehow emulated for the new
+			 * environment, they are not relevant and so are other
+			 * runtime only things (e.g. getenv, uname, ...).
+			 * Switch to offline mode. We may add a separate
+			 * mechanism to control this behaviour in the future.
+			 */
+			dI("Switching probe to PROBE_OFFLINE_CHROOT mode.");
+			probe->selected_offline_mode = PROBE_OFFLINE_CHROOT;
+		}
+	}
+
+	if (getenv("OSCAP_PROBE_RPMDB_PATH") != NULL) {
+		dI("Switching probe to PROBE_OFFLINE_RPMDB mode.");
+		probe->selected_offline_mode = PROBE_OFFLINE_RPMDB;
+	}
+#endif
+
 	SEXP_t *probe_in, *probe_out, *set;
 
 	if (msg_in == NULL) {