--- /dev/null
+#include <stdlib.h>
+#include <syslog.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+extern const char **environ;
+
+
+#define ZONE "kratochvil.vellum.cz"
+
+#define SETUID 0 /* user UID */
+#define SETGID 0 /* group GID */
+#define PERMITTED_ENV_LIST "PWD"
+#define EXEC_PATHNAME "/usr/sbin/ndc"
+#define EXEC_ARGV "/usr/sbin/ndc","reload",ZONE,NULL
+
+
+#ifndef G_GNUC_NORETURN
+#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ > 4)
+#define G_GNUC_NORETURN __attribute__((noreturn))
+#else /* !__GNUC__ */
+#define G_GNUC_NORETURN
+#endif /* !__GNUC__ */
+#endif /* !G_GNUC_NORETURN */
+
+#define EXITLOG(msg...) do {\
+ openlog("pserverchroot",LOG_PID,LOG_DAEMON); \
+ syslog(LOG_CRIT,msg); \
+ closelog(); \
+ exit(EXIT_FAILURE); \
+ } while (0)
+
+#define LENGTH(x) (sizeof((x))/sizeof(*(x)))
+
+#define FUNCCHK(funcname,args...) do { \
+ if (errno=0,funcname(args)) \
+ funcfail( #funcname ); \
+ } while (0)
+
+static void funcfail(const char *funcname) G_GNUC_NORETURN;
+static void funcfail(const char *funcname)
+{
+ EXITLOG("Unable to %s(2): %s",funcname,strerror(errno));
+}
+
+int main(int argc,char **argv)
+{
+int total=0;
+const char *allowed[]={ PERMITTED_ENV_LIST };
+const char **allp,**envp;
+char *dup=NULL,*s;
+
+retry:
+ for (envp=environ;*envp;envp++) {
+ if (dup) free(dup);
+ dup=strdup(*envp);
+ if ((s=strchr(dup,'='))) *s='\0';
+ for (allp=allowed;allp<allowed+LENGTH(allowed);allp++)
+ if (!strcmp(dup,*allp)) goto ok;
+ if (total++>1000)
+ EXITLOG("Unable to clean environment for 'ndc': %s",*envp);
+ unsetenv(dup);
+ goto retry;
+ok:;
+ }
+ FUNCCHK(setenv,"PATH","/usr/bin",1);
+ FUNCCHK(chdir,"/");
+ FUNCCHK(setgid,SETGID);
+ FUNCCHK(setuid,SETUID);
+ errno=0,execl(EXEC_PATHNAME,EXEC_ARGV);
+ funcfail("execl");
+}