commit 872a717687a377cc02860e44c67dc1934ebfa9cb
from: Omar Polo <op@omarpolo.com>
date: Sun Nov 27 10:05:13 2022 UTC

when switching user also set the groups

commit - b24c6fcc1c81fa2a6b71048a9d2fc532402448b7
commit + 872a717687a377cc02860e44c67dc1934ebfa9cb
blob - 0e7918b31992ce016980ae8d45d477a32e0a9ca8
blob + 4908c7b507139ab648fab8edd7d14232f1dce344
--- gmid.c
+++ gmid.c
@@ -296,9 +296,10 @@ drop_priv(void)
 	}
 
 	if (pw != NULL) {
-		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
-			fatal("setresuid(%d): %s", pw->pw_uid,
-			    strerror(errno));
+		if (setgroups(1, &pw->pw_gid) == -1 ||
+		    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1 ||
+		    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
+			fatal("cannot drop privileges");
 	}
 
 	if (getuid() == 0)