💾 Archived View for thrig.me › blog › 2023 › 05 › 07 › wrap.c captured on 2023-11-14 at 09:18:08.

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// wrap - prevent unveil.pl from reading /etc/passwd (and other files)

#include <err.h>
#include <unistd.h>

int
main(int argc, char *argv[], char *envp[])
{
	char *prog = "/usr/bin/perl";

	// Perl needs to read a bunch of files from here
	if (unveil("/usr", "r") == -1) err(1, "unveil");

	// and this program needs to be able to exec perl
	if (unveil(prog, "x") == -1) err(1, "unveil");

	// and unveil.pl needs to be readable by perl
	if (unveil(".", "r") == -1) err(1, "unveil");

	if (pledge("exec stdio", "cpath prot_exec rpath stdio") == -1)
		err(1, "pledge");
	execl(prog, "perl", "unveil.pl", (char *) 0);
}