81 lines
3.9 KiB
C
81 lines
3.9 KiB
C
#include<sys/prctl.h>
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#include<sys/mount.h>
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#include<sys/stat.h>
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static void procfs_prepare()
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{
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if (mkdir("/proc", 0555) && errno != EEXIST) die("Failed to mkdir /proc: %m\n");
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if (mount("proc", "/proc", "proc", 0, "")) die("Failed to mount proc: %m\n");
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}
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#define hostname "runner"
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#define put_old "oldfs"
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void mnt_prepare(char* rootfs, char* shared_mountpoint) {
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char* shared_folder=NULL;
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asprintf(&shared_folder,"../%s",shared_mountpoint);
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if (mount(rootfs,rootfs,"ext4",MS_BIND,"")) die("failed to mount %s: %m", rootfs);
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if (chdir(rootfs)) die("falied to cd:%m");
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//if (mount("/sys","sys","sysfs",0,"")) die("failed to mount sysfs: %m");
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//if (mount("/dev","dev","udev",0,"")) die("failed to mount: %m");
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if (mkdir("shared", 0777) && errno != EEXIST) die("Failed to mkdir %s: %m\n", shared_mountpoint);
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if (mount(shared_folder,"shared","ext4",MS_BIND,"")) die("failed to mount shared folder: %m");
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if (mkdir(put_old, 0000) && errno != EEXIST) die("Failed to mkdir %s: %m\n", put_old);
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if (syscall(SYS_pivot_root, ".", put_old)) die("Failed to pivot_root from %s to %s: %m\n", rootfs, put_old);
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if (chdir("/")) die("Failed to chdir to new root: %m\n");
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procfs_prepare();
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if (umount2(put_old, MNT_DETACH)) die("Failed to umount put_old %s: %m\n", put_old);
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if (rmdir(put_old)) die("Failed to rmdir: %m");
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free(shared_folder);
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}
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void ro_fs(char* shared_mountpoint) {
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char* shared_folder = malloc(strlen(shared_mountpoint)+4);
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strcpy(shared_folder,"../");
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strcat(shared_folder,shared_mountpoint);
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if (mount("/","/","ext4",MS_REMOUNT | MS_RDONLY| MS_BIND,"")) die("failed to mount: %m");
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if (mount(shared_mountpoint,"shared","ext4",MS_REMOUNT | MS_BIND,"")) die("failed to mount: %m");
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free(shared_folder);
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}
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//#undef shared_mountpoint
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//#undef shared_folder
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#undef put_old
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void await_setup(int pipe) { // wait for signal from parent
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char buf[2];
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if (read(pipe, buf, 2) != 2) die("Failed to read from pipe: %m\n");
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}
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static int nsrun(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 params *params = (struct params*) arg;
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await_setup(params->fd[0]);
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char cwd[PATH_MAX];
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if(getcwd(cwd,sizeof(cwd))==NULL) die("getcwd error: %m");
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if(chdir(params->shared_folder)) die("failed to chdir to shared folder: %m")
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int out_fd=open("out",O_WRONLY|O_CREAT,0666);
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if(out_fd==-1) die("unable to open output file:%m")
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else dup2(out_fd,STDOUT_FILENO);
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int in_fd=open("in",O_RDONLY|O_CREAT,0666);
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if(in_fd==-1) die("unable to open input file:%m")
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else dup2(in_fd,STDIN_FILENO);
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int err_fd=open("err",O_WRONLY|O_CREAT,0666);
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if(err_fd==-1) die("unable to open error file:%m")
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else dup2(err_fd,STDERR_FILENO);
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if(chdir(cwd)) die("failed to chdir: %m");
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mnt_prepare("minrootfs",params->shared_folder);
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sethostname(hostname,sizeof(hostname));
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ro_fs(params->shared_folder);
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if(setgid(1000)) die("failed to setgid:%m");
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if(setuid(1000)) die("failed to setuid:%m");
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char** argv = params->argv;
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char* cmd = argv[0];
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char* env[]={
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"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
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"PWD=/",
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NULL,
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};
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if (execve(cmd,argv,env) == -1) die("failed to exec,%m");
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return 1;
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}
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