131 lines
3.9 KiB
C
131 lines
3.9 KiB
C
#define _GNU_SOURCE
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#include <sys/wait.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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#include <sched.h>
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#include <sys/syscall.h>
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#include <linux/sched.h>
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#include <stdarg.h>
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#include <time.h>
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#include <limits.h>
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#include <signal.h>
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#include "util.h"
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struct params {
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char* shared_folder;
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int fd[2];
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int out_fd;
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char **argv;
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};
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struct limits {
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size_t memory;
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int core;
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int time;
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};
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struct killparams{
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int time;
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int pid;
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};
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#define READ_SIZE 100
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char read_buf[READ_SIZE + 1];
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#include "ns_exec.c"
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#include "cgroup_prepare.c"
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//time limit realisation
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static int killafter(void *arg) {
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//die when parent dies
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if (prctl(PR_SET_PDEATHSIG, SIGKILL)) die("cannot PR_SET_PDEATHSIG for child process: %m\n");
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struct killparams* params = (struct killparams*) arg;
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struct timespec tw = {params -> time / 1000, ((params->time) % 1000) * 1000000};
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struct timespec tr;
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nanosleep(&tw, &tr);
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kill(params->pid, SIGKILL);
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}
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#define STACK_SIZE 1000000
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static char nmstack[STACK_SIZE];
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static char killstack[STACK_SIZE];
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static void parse_args(int argc, char **argv, struct params *params,struct limits *limits){
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if (argc < 6) {
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puts("usage:\n starter <core_id> <memory_amount> <time limit in ms> <shared folder> <command, arg1,arg2,...>");
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exit(0);
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}
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argc--; argv++;
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limits->core = atoi(argv[0]);
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argc--; argv++;
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limits->memory = atoi(argv[0]);
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argc--; argv++;
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limits->time = atoi(argv[0]);
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argc--; argv++;
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params->shared_folder = argv[0];
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argc--; argv++;
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params->argv = argv;
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}
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//setup user namespace
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static void prepare_userns(int pid) {
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char path[100];
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char line[100];
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int uid = 0;//root
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int gid = 0;//root
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int unprivileged_uid = 66534;//nobody
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int unprivileged_gid = 65534;//nogroup
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sprintf(path, "/proc/%d/uid_map", pid);
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sprintf(line, "0 %d 1\n1 %d 1000\n", uid, unprivileged_uid);//map root to uid 0,nobody to uid 1000
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write_file(path, line);
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sprintf(path, "/proc/%d/setgroups", pid);
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sprintf(line, "deny");
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write_file(path, line);
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sprintf(path, "/proc/%d/gid_map", pid);
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sprintf(line, "0 %d 1\n1 %d 1000\n", gid, unprivileged_gid);//map root to gid 0,nogroup to gid 1000
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write_file(path, line);
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}
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int main(int argc,char** argv) {
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if(setuid(0)) die("need to be run as root");
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if(setgid(0)) die("need to be run as root");
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//get binary folder
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char bin_path[PATH_MAX];
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if (realpath (argv[0], bin_path) == 0) die("unable to resolve real path: %m");//get absolute path to executable
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for(int i = strlen(bin_path); i > 0 && bin_path[i] != '/';i--) bin_path[i]=0;//cut filename to get directory name
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if(chdir(bin_path)) die("unable to chdir to binary path: %m");
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//set random seed
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srand(time(NULL));
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//setup parameters
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struct params params;
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memset(¶ms, 0, sizeof(struct params));
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struct limits limits;
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memset(&limits, 0, sizeof(struct limits));
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parse_args(argc, argv, ¶ms, &limits);
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prepare_cgroup(&limits);
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if (pipe(params.fd) < 0) die("can't open pipe: %m");//a pipe to report readiness
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int clone_flags = SIGCHLD | CLONE_NEWUTS | CLONE_NEWUSER | CLONE_NEWNS | CLONE_NEWPID | CLONE_NEWNET | CLONE_NEWIPC | CLONE_NEWCGROUP;
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int nsrun_pid = clone(nsrun, nmstack + STACK_SIZE, clone_flags, ¶ms);//make new namespace
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int pipe = params.fd[1];
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prepare_userns(nsrun_pid);
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if (nsrun_pid < 0) die("faled to clone");
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add_to_cgroup(nsrun_pid);
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if (write(pipe, "OK", 2) != 2) die("Failed to write to pipe: %m");//report readiness
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struct killparams killparams;
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killparams.time = limits.time;
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killparams.pid = nsrun_pid;
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clone(killafter, killstack + STACK_SIZE, SIGCHLD, &killparams);
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if (waitpid(nsrun_pid, NULL, 0) == -1) die("Failed to wait pid %d: %m\n", nsrun_pid);
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remove_cgroup();
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return 0;
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}
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