spike dnet_intf_get_dst: droppriv

1 files changed, 29 insertions, 0 deletions

diff --git a/spike/dnet_intf_get_dst.c b/spike/dnet_intf_get_dst.c
index ed0f3ce..c629f7f 100644
--- a/spike/dnet_intf_get_dst.c
+++ b/spike/dnet_intf_get_dst.c
@@ -1,5 +1,32 @@
 #include <dnet.h>
 #include <stdio.h>
+#include <pwd.h>
+#include <grp.h>
+
+void
+_droppriv(char *user, int do_chroot, char *chroot_path)
+{
+	struct passwd   *pw;
+
+	pw = getpwnam(user);
+	if (!pw)
+		err(1, "unknown user %s", user);
+	if (do_chroot) {
+		if (!chroot_path)
+			chroot_path = pw->pw_dir;
+		if (chroot(chroot_path) != 0)
+			err(1, "unable to chroot");
+	}
+	if (chdir("/") != 0)
+		err(1, "unable to chdir");
+	if (setgroups(1, &pw->pw_gid) == -1)
+		err(1, "setgroups() failed");
+	if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1)
+		err(1, "setresgid failed");
+	if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
+		err(1, "setresuid() failed");
+	endpwent();
+}
 
 int
 main(int argc, char **argv) {
@@ -15,6 +42,8 @@ main(int argc, char **argv) {
 	addr_aton(argv[1], &dst);
 	printf("dst: %s\n", addr_ntoa(&dst));
 
+	_droppriv("nobody", 1, NULL); /* bad practise, use dedicated user */
+
 	intf = intf_open();
 
 	err = intf_get_dst(intf, &entry, &dst);