From 23e9693641d1796adffca04c33518dc366dcea1f Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Tue, 22 Dec 2015 09:48:11 +0100
Subject: [PATCH] Allow chrooting the application

---
 Tools/sitl_run.sh            | 15 ++++++++++++---
 src/platforms/posix/main.cpp | 35 ++++++++++++++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/Tools/sitl_run.sh b/Tools/sitl_run.sh
index dcfd21930b..a30897fe7a 100755
--- a/Tools/sitl_run.sh
+++ b/Tools/sitl_run.sh
@@ -14,6 +14,15 @@ echo program: $program
 echo model: $model
 echo build_path: $build_path
 
+if [ "$chroot" == "1" ]
+then
+	chroot_enabled=-c
+	sudo_enabled=sudo
+else
+	chroot_enabled=""
+	sudo_enabled=""
+fi
+
 if [ "$model" == "" ] || [ "$model" == "none" ]
 then
 	echo "empty model, setting iris as default"
@@ -48,7 +57,7 @@ if [ "$program" == "jmavsim" ] && [ "$no_sim" == "" ]
 then
 	cd Tools/jMAVSim
 	ant
-	nice -n -10 java -Djava.ext.dirs= -cp lib/*:out/production/jmavsim.jar me.drton.jmavsim.Simulator -udp 127.0.0.1:14560 &
+	java -Djava.ext.dirs= -cp lib/*:out/production/jmavsim.jar me.drton.jmavsim.Simulator -udp 127.0.0.1:14560 &
 	SIM_PID=`echo $!`
 elif [ "$program" == "gazebo" ] && [ "$no_sim" == "" ]
 then
@@ -65,7 +74,7 @@ then
 		cd Tools/sitl_gazebo/Build
 		cmake -Wno-dev ..
 		make -j4
-		nice -n -10 gzserver --verbose ../worlds/${model}.world &
+		gzserver --verbose ../worlds/${model}.world &
 		SIM_PID=`echo $!`
 		gzclient --verbose &
 		GUI_PID=`echo $!`
@@ -96,7 +105,7 @@ elif [ "$debugger" == "valgrind" ]
 then
 	valgrind ./mainapp ../../../../${rc_script}_${program}_${model}
 else
-	nice -n -10 ./mainapp ../../../../${rc_script}_${program}_${model}
+	$sudo_enabled ./mainapp $chroot_enabled ../../../../${rc_script}_${program}_${model}
 fi
 
 if [ "$program" == "jmavsim" ]
diff --git a/src/platforms/posix/main.cpp b/src/platforms/posix/main.cpp
index 7bf431b4f4..24ba4f6e66 100644
--- a/src/platforms/posix/main.cpp
+++ b/src/platforms/posix/main.cpp
@@ -44,6 +44,7 @@
 #include <sstream>
 #include <vector>
 #include <signal.h>
+#include <unistd.h>
 #include "apps.h"
 #include "px4_middleware.h"
 #include "DriverFramework.hpp"
@@ -157,6 +158,7 @@ static void process_line(string &line, bool exit_on_fail)
 int main(int argc, char **argv)
 {
 	bool daemon_mode = false;
+	bool chroot_on = false;
 	signal(SIGINT, _SigIntHandler);
 	signal(SIGFPE, _SigFpeHandler);
 
@@ -174,6 +176,9 @@ int main(int argc, char **argv)
 				usage();
 				return 0;
 
+			} else if (strcmp(argv[index], "-c") == 0) {
+				chroot_on = true;
+
 			} else {
 				PX4_WARN("Unknown/unhandled parameter: %s", argv[index]);
 				return 1;
@@ -203,7 +208,7 @@ int main(int argc, char **argv)
 
 		px4::init(argc, argv, "mainapp");
 
-		//if commandfile is present, process the commands from the file
+		// if commandfile is present, process the commands from the file
 		if (commands_file != nullptr) {
 			ifstream infile(commands_file);
 
@@ -217,6 +222,34 @@ int main(int argc, char **argv)
 			}
 		}
 
+		if (chroot_on) {
+			// Lock this application in the current working dir
+			// this is not an attempt to secure the environment,
+			// rather, to replicate a deployed file system.
+			char pwd_path[PATH_MAX];
+			const char *folderpath = "/rootfs/";
+
+			if (nullptr == getcwd(pwd_path, sizeof(pwd_path))) {
+				PX4_ERR("Failed aquiring working dir, abort.");
+				exit(1);
+			}
+
+			if (nullptr == strcat(pwd_path, folderpath)) {
+				PX4_ERR("Failed completing path, abort.");
+				exit(1);
+			}
+
+			if (chroot(pwd_path)) {
+				PX4_ERR("Failed chrooting application, path: %s, error: %s.", pwd_path, strerror(errno));
+				exit(1);
+			}
+
+			if (chdir("/")) {
+				PX4_ERR("Failed changing to root dir, path: %s, error: %s.", pwd_path, strerror(errno));
+				exit(1);
+			}
+		}
+
 		if (!daemon_mode) {
 			string mystr = "";
 			string string_buffer[CMD_BUFF_SIZE];