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Commit 8aeb36e8 authored by Philip Sanderson's avatar Philip Sanderson Committed by Rusty Russell
Browse files

lguest: --username and --chroot options 



I've attached a patch which implements dropping to privileges
and chrooting to a directory.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 8a335bc6

Documentation/lguest/lguest.c

+50 −0
Original line number Diff line number Diff line
@@ -39,6 +39,9 @@ 
#include <limits.h>

#include <stddef.h>

#include <signal.h>

#include <pwd.h>

#include <grp.h>



#include <linux/virtio_config.h>

#include <linux/virtio_net.h>

#include <linux/virtio_blk.h>
@@ -1872,6 +1875,8 @@ static struct option opts[] = { 
	{ "block", 1, NULL, 'b' },

	{ "rng", 0, NULL, 'r' },

	{ "initrd", 1, NULL, 'i' },

	{ "username", 1, NULL, 'u' },

	{ "chroot", 1, NULL, 'c' },

	{ NULL },

};

static void usage(void)
@@ -1894,6 +1899,12 @@ int main(int argc, char *argv[]) 
	/* If they specify an initrd file to load. */

	const char *initrd_name = NULL;



	/* Password structure for initgroups/setres[gu]id */

	struct passwd *user_details = NULL;



	/* Directory to chroot to */

	char *chroot_path = NULL;



	/* Save the args: we "reboot" by execing ourselves again. */

	main_args = argv;
@@ -1950,6 +1961,14 @@ int main(int argc, char *argv[]) 
		case 'i':

			initrd_name = optarg;

			break;

		case 'u':

			user_details = getpwnam(optarg);

			if (!user_details)

				err(1, "getpwnam failed, incorrect username?");

			break;

		case 'c':

			chroot_path = optarg;

			break;

		default:

			warnx("Unknown argument %s", argv[optind]);

			usage();
@@ -2021,6 +2040,37 @@ int main(int argc, char *argv[]) 
	/* If we exit via err(), this kills all the threads, restores tty. */

	atexit(cleanup_devices);



	/* If requested, chroot to a directory */

	if (chroot_path) {

		if (chroot(chroot_path) != 0)

			err(1, "chroot(\"%s\") failed", chroot_path);



		if (chdir("/") != 0)

			err(1, "chdir(\"/\") failed");



		verbose("chroot done\n");

	}



	/* If requested, drop privileges */

	if (user_details) {

		uid_t u;

		gid_t g;



		u = user_details->pw_uid;

		g = user_details->pw_gid;



		if (initgroups(user_details->pw_name, g) != 0)

			err(1, "initgroups failed");



		if (setresgid(g, g, g) != 0)

			err(1, "setresgid failed");



		if (setresuid(u, u, u) != 0)

			err(1, "setresuid failed");



		verbose("Dropping privileges completed\n");

	}



	/* Finally, run the Guest.  This doesn't return. */

	run_guest();

}