Close all the fds of the child before exec

This patch closes all the fds (starting from 3) of
the child before exec in InstanceTask.

Please see the bug description for more details.

Change-Id: I9f18f88c9c58540ad6358a2a989f344f60be86d8
Closes-bug: #1394300

src/vnsw/agent/cmn/agent_cmn.h

@@ -9,6 +9,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <net/address.h>
+#include <unistd.h>
 
 #include <boost/intrusive_ptr.hpp>
 #include <boost/bind.hpp>
@@ -73,6 +74,13 @@ static inline void CfgUuidSet(uint64_t ms_long, uint64_t ls_long,
     }
 }
 
+static inline void CloseTaskFds(void) {
+    int max_open_fds = sysconf(_SC_OPEN_MAX);
+    int fd;
+    for(fd = 3; fd < max_open_fds; fd++)
+        close(fd);
+}
+
 extern SandeshTraceBufferPtr OperDBTraceBuf;
 extern bool GetBuildInfo(std::string &build_info_str);
 

src/vnsw/agent/oper/instance_task.cc

@@ -93,6 +93,8 @@ pid_t InstanceTask::Run() {
         close(STDOUT_FILENO);
         close(STDIN_FILENO);
 
+        /* Close all the open fds before execvp */
+        CloseTaskFds();
         execvp(c_argv[0], (char **) c_argv.data());
         perror("execvp");
 

src/vnsw/agent/oper/instance_task.h

@@ -9,6 +9,7 @@
 #include "base/timer.h"
 #include "base/queue_task.h"
 #include "cmn/agent_signal.h"
+#include "cmn/agent_cmn.h"
 #include "db/db_entry.h"
 
 class EventManager;

src/vnsw/agent/oper/test/SConscript

@@ -22,6 +22,7 @@ test_fabric_interface = AgentEnv.MakeTestCmd(env, 'test_fabric_interface',
                                              oper_flaky_test_suite)
 test_aap = AgentEnv.MakeTestCmd(env, 'test_aap', oper_flaky_test_suite)
 test_ipv6 = AgentEnv.MakeTestCmd(env, 'test_ipv6', oper_test_suite)
+test_instance_task = AgentEnv.MakeTestCmd(env, 'test_instance_task', oper_test_suite)
 env.Alias('agent:test_ipv6', test_ipv6)
 
 env.Append(LIBPATH = [

src/vnsw/agent/oper/test/test_instance_task.cc

@@ -0,0 +1,94 @@
+#include "oper/instance_task.h"
+#include "testing/gunit.h"
+
+#include <boost/filesystem.hpp>
+#include <boost/bind.hpp>
+#include <sstream>
+#include <fstream>
+
+#include <cstdlib>
+#include <boost/uuid/random_generator.hpp>
+
+#include "io/event_manager.h"
+#include "base/logging.h"
+#include "base/os.h"
+#include "base/test/task_test_util.h"
+
+using namespace std;
+using namespace boost::filesystem;
+
+class InstanceTaskFdTest : public ::testing::Test {
+public:
+    virtual void SetUp() {
+        memset(tmpfilename, 0, sizeof(tmpfilename));
+        strcpy(tmpfilename, "task_fd_XXXXXX");
+        mkstemp(tmpfilename);
+        std::fstream testfile(tmpfilename);
+        testfile << "while true; do sleep 1; done";
+        testfile.close();
+        std::stringstream cmd_str;
+        cmd_str << "/bin/sh" << " " <<tmpfilename;
+        task_ = new InstanceTask(cmd_str.str(), 1, &evm);
+    }
+
+    virtual void TearDown() {
+        delete task_;
+        remove(tmpfilename);
+    }
+
+    int StartTask() {
+        /* create few fds */
+        if(pipe(pipe_fds) == -1)
+            return -1;
+        sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
+        if (sock_fd < 0)
+            return -1;
+        /* run the task now */
+        task_pid = task_->Run();
+        return task_pid;
+    }
+
+    int StopTask() {
+        task_->Stop();
+        close(pipe_fds[0]);
+        close(pipe_fds[1]);
+        close(sock_fd);
+    }
+
+    int GetTaskFds() {
+        std::stringstream proc_path;
+        int no_of_fds;
+        proc_path << "/proc/" <<task_pid<<"/fd/";
+        path the_path(proc_path.str());
+        no_of_fds = std::count_if(directory_iterator(the_path),
+                                  directory_iterator(),
+                                  bind( static_cast<bool(*)(const path&)>(is_other),
+                                  bind( &directory_entry::path, _1)));
+        return no_of_fds;
+    }
+
+protected:
+    int pipe_fds[2];
+    int sock_fd;
+    InstanceTask *task_;
+    int task_pid;
+    EventManager evm;
+    char tmpfilename[L_tmpnam];
+};
+
+TEST_F(InstanceTaskFdTest, TestCloseTaskFds) {
+    task_pid = StartTask();
+    EXPECT_TRUE(task_pid > 0);
+    int task_open_fds = GetTaskFds();
+    StopTask();
+    /* The task should have only 1 opened fd (i.e fd 2) */
+    EXPECT_EQ(1U, task_open_fds);
+};
+
+int main(int argc, char **argv) {
+    LoggingInit();
+    ::testing::InitGoogleTest(&argc, argv);
+
+    int result = RUN_ALL_TESTS();
+    return result;
+}

src/vnsw/agent/uve/vm_stat.cc

@@ -5,6 +5,7 @@
 #include <sys/times.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <unistd.h>
 #include <uve/vm_stat.h>
 #include <uve/vm_stat_data.h>
 #include <db/db.h>
@@ -87,6 +88,9 @@ void VmStat::ExecCmd(std::string cmd, DoneCb cb) {
         dup2(out[1], STDOUT_FILENO);
         //Close out[1] as stdout is a exact replica of out[1]
         close(out[1]);
+
+        /* Close all the open fds before execvp */
+        CloseTaskFds();
         execvp(argv[0], argv);
         perror("execvp");
         exit(127);