Question

I know that use the command “chroot” in linux need some files or directories such as usr, bin and so on. But when I use the function chroot() in C, do I need these files?

Here is my code, which “hw.out” is a binary file which just print “Hello, world”. I compiled it and run it as root, but it was failed to print “Hello, world”. What else should I do? Thank you!

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    int result = chroot(".");

    if(result == 0)
        printf("Chroot Succese.\n");

    char *arrays[]={"./hw.out",NULL};
    execvp("./hw.out", arrays);
    return 0;
}

Answer 1

execvp is most likely failing, probably with ENOENT: no such file or directory, if hw.out is a dynamically linked executable.

For that to work, all the libraries required by hw.out need to be findable in the chrooted environment.

Try linking hw.out statically, and it should work. (And add error checking after execvp to see what errno is set to after the call if it returns.)