code prettyfing

main.go

@@ -1,10 +1,6 @@
 package main
 
 import (
-    //"os"
-    //"fmt"
-    //"log"
-    //exec "os/exec"
     runner "runner/runner"
 )
 

runner/runner.go

@@ -1,7 +1,6 @@
 package runner
 
 import (
-    //"errors"
     "bytes"
     "io"
     "fmt"
@@ -75,18 +74,14 @@ func IsolatedRun(command []string,limits Limits) {
     var runId string
     for i := 0; i < runIdLength; i++ {runId += string('a' + byte(rand.Int31n(26)))}
     os.Mkdir("starter/" + runId, 0777)
-    //log.Printf("%d",limits.Core)
-    //exec.Command("starter/starter", string(limits.Core),string(limits.Memory),string(limits.Time),runId,command...);
     args := []string{string(limits.Core), string(limits.Memory), string(limits.Time), runId}
     args = append(args, command...)
-    cmd:=exec.Command("/root/runner/starter/starter",args...)
-    //cmd:=exec.Command("/usr/bin/echo","123")
+    cmd := exec.Command("starter/starter", args...)
     var stdBuffer bytes.Buffer
     mw := io.MultiWriter(os.Stdout, &stdBuffer)
     cmd.Stdout = mw
     err := cmd.Run();
     if err != nil { log.Fatal(err) }
-    //log.Println(stdBuffer.String())
     os.RemoveAll("starter/" + runId)
     cmd.Wait()
 }

starter/starter.c

@@ -39,6 +39,7 @@ char read_buf[READ_SIZE+1];
 #include "ns_exec.c"
 #include "cgroup_prepare.c"
 
+//time limit realisation
 static int killafter(void *arg) {
     //die when parent dies
     if (prctl(PR_SET_PDEATHSIG, SIGKILL)) die("cannot PR_SET_PDEATHSIG for child process: %m\n");
@@ -49,7 +50,6 @@ static int killafter(void *arg) {
     kill(params->pid, SIGKILL);
 }
 
-//const size_t STACK_SIZE=1000000;
 #define STACK_SIZE 1000000
 static char nmstack[STACK_SIZE];
 static char killstack[STACK_SIZE];
@@ -72,17 +72,18 @@ static void parse_args(int argc, char **argv, struct params *params,struct limit
     params->argv = argv;
 }
 
+//setup user namespace
 static void prepare_userns(int pid) {
     char path[100];
     char line[100];
 
-    int uid = 0;
-    int gid = 0;
-    int unprivileged_uid=66534;
-    int unprivileged_gid=65534;
+    int uid = 0;//root
+    int gid = 0;//root
+    int unprivileged_uid = 66534;//nobody
+    int unprivileged_gid = 65534;//nogroup
 
     sprintf(path, "/proc/%d/uid_map", pid);
-    sprintf(line, "0 %d 1\n1 %d 1000\n", uid, unprivileged_uid);
+    sprintf(line, "0 %d 1\n1 %d 1000\n", uid, unprivileged_uid);//map root to uid 0,nobody to uid 1000
     write_file(path, line);
 
     sprintf(path, "/proc/%d/setgroups", pid);
@@ -90,35 +91,34 @@ static void prepare_userns(int pid) {
     write_file(path, line);
 
     sprintf(path, "/proc/%d/gid_map", pid);
-    sprintf(line, "0 %d 1\n1 %d 1000\n", gid, unprivileged_gid);
+    sprintf(line, "0 %d 1\n1 %d 1000\n", gid, unprivileged_gid);//map root to gid 0,nogroup to gid 1000
     write_file(path, line);
 }
 
 int main(int argc,char** argv) {
     if(setuid(0)) die("need to be run as root");
     if(setgid(0)) die("need to be run as root");
-    //getting binary folder
+    //get binary folder
     char bin_path[PATH_MAX];
-    if (realpath (argv[0], bin_path) == 0) die("unable to resolve real path: %m"); 
-    for(int i = strlen(bin_path);i>0 && bin_path[i]!='/';i--) bin_path[i]=0;
+    if (realpath (argv[0], bin_path) == 0) die("unable to resolve real path: %m");//get absolute path to executable
+    for(int i = strlen(bin_path); i > 0 && bin_path[i] != '/';i--) bin_path[i]=0;//cut filename to get directory name
     if(chdir(bin_path)) die("unable to chdir to binary path: %m");
-    //setting random seed
+    //set random seed
     srand(time(NULL));
+    //setup parameters
     struct params params;
     memset(&params, 0, sizeof(struct params));
     struct limits limits;
     memset(&limits, 0, sizeof(struct limits));
     parse_args(argc, argv, &params, &limits);
     prepare_cgroup(&limits);
-    if (pipe(params.fd) < 0) die("can't open pipe: %m");
-    int clone_flags = SIGCHLD | CLONE_NEWUTS | CLONE_NEWUSER | CLONE_NEWNS | CLONE_NEWPID | CLONE_NEWNET | CLONE_NEWIPC | CLONE_NEWCGROUP/* | CLONE_NEWTIME*/;
-    int nsrun_pid=clone(nsrun,nmstack+STACK_SIZE,clone_flags,&params);
+    if (pipe(params.fd) < 0) die("can't open pipe: %m");//a pipe to report readiness
+    int clone_flags = SIGCHLD | CLONE_NEWUTS | CLONE_NEWUSER | CLONE_NEWNS | CLONE_NEWPID | CLONE_NEWNET | CLONE_NEWIPC | CLONE_NEWCGROUP;
+    int nsrun_pid = clone(nsrun, nmstack + STACK_SIZE, clone_flags, &params);//make new namespace
     int pipe = params.fd[1];
-    //sleep(1);
     prepare_userns(nsrun_pid);
-    if (nsrun_pid<0) {die("faled to clone");}
+    if (nsrun_pid < 0) die("faled to clone");
     add_to_cgroup(nsrun_pid);
-    //dup2(STDOUT_FILENO,params.out[0]);
     if (write(pipe, "OK", 2) != 2) die("Failed to write to pipe: %m");//report readiness
     struct killparams killparams;
     killparams.time = limits.time;