/* This is copied from portmap 4.0-29 in RedHat. */ /* * pmap_check - additional portmap security. * * Always reject non-local requests to update the portmapper tables. * * Refuse to forward mount requests to the nfs mount daemon. Otherwise, the * requests would appear to come from the local system, and nfs export * restrictions could be bypassed. * * Refuse to forward requests to the nfsd process. * * Refuse to forward requests to NIS (YP) daemons; The only exception is the * YPPROC_DOMAIN_NONACK broadcast rpc call that is used to establish initial * contact with the NIS server. * * Always allocate an unprivileged port when forwarding a request. * * If compiled with -DCHECK_PORT, require that requests to register or * unregister a privileged port come from a privileged port. This makes it * more difficult to replace a critical service by a trojan. * * If compiled with -DHOSTS_ACCESS, reject requests from hosts that are not * authorized by the /etc/hosts.{allow,deny} files. The local system is * always treated as an authorized host. The access control tables are never * consulted for requests from the local system, and are always consulted * for requests from other hosts. * * Author: Wietse Venema (wietse@wzv.win.tue.nl), dept. of Mathematics and * Computing Science, Eindhoven University of Technology, The Netherlands. */ #include "tcpwrapper.h" #include #include #include #include #include #include #include #include #include #ifdef SYSV40 #include #include #endif static void logit(); static void toggle_verboselog(); int verboselog = 0; int allow_severity = LOG_INFO; int deny_severity = LOG_WARNING; /* A handful of macros for "readability". */ /* coming from libwrap.a (tcp_wrappers) */ extern int hosts_ctl(char *daemon, char *name, char *addr, char *user); #define legal_port(a,p) \ (ntohs((a)->sin_port) < IPPORT_RESERVED || (p) >= IPPORT_RESERVED) #define log_bad_port(addr, proc, prog) \ logit(deny_severity, addr, proc, prog, ": request from unprivileged port") #define log_bad_host(addr, proc, prog) \ logit(deny_severity, addr, proc, prog, ": request from unauthorized host") #define log_bad_owner(addr, proc, prog) \ logit(deny_severity, addr, proc, prog, ": request from non-local host") #define log_no_forward(addr, proc, prog) \ logit(deny_severity, addr, proc, prog, ": request not forwarded") #define log_client(addr, proc, prog) \ logit(allow_severity, addr, proc, prog, "") int good_client(daemon, addr) char *daemon; struct sockaddr_in *addr; { struct hostent *hp; char **sp; char *tmpname; /* Check the IP address first. */ if (hosts_ctl(daemon, "", inet_ntoa(addr->sin_addr), "")) return 1; /* Check the hostname. */ hp = gethostbyaddr ((const char *) &(addr->sin_addr), sizeof (addr->sin_addr), AF_INET); if (!hp) return 0; /* must make sure the hostent is authorative. */ tmpname = alloca (strlen (hp->h_name) + 1); strcpy (tmpname, hp->h_name); hp = gethostbyname(tmpname); if (hp) { /* now make sure the "addr->sin_addr" is on the list */ for (sp = hp->h_addr_list ; *sp ; sp++) { if (memcmp(*sp, &(addr->sin_addr), hp->h_length)==0) break; } if (!*sp) /* it was a FAKE. */ return 0; } else /* never heard of it. misconfigured DNS? */ return 0; /* Check the official name first. */ if (hosts_ctl(daemon, "", hp->h_name, "")) return 1; /* Check aliases. */ for (sp = hp->h_aliases; *sp ; sp++) { if (hosts_ctl(daemon, "", *sp, "")) return 1; } /* No match */ return 0; } /* check_startup - additional startup code */ void check_startup() { /* * Give up root privileges so that we can never allocate a privileged * port when forwarding an rpc request. * * Fix 8/3/00 Philipp Knirsch: First lookup our rpc user. If we find it, * switch to that uid, otherwise simply resue the old bin user and print * out a warning in syslog. */ struct passwd *pwent; pwent = getpwnam("rpc"); if (pwent == NULL) { syslog(LOG_WARNING, "user rpc not found, reverting to user bin"); if (setuid(1) == -1) { syslog(LOG_ERR, "setuid(1) failed: %m"); exit(1); } } else { if (setuid(pwent->pw_uid) == -1) { syslog(LOG_WARNING, "setuid() to rpc user failed: %m"); if (setuid(1) == -1) { syslog(LOG_ERR, "setuid(1) failed: %m"); exit(1); } } } (void) signal(SIGINT, toggle_verboselog); } /* check_default - additional checks for NULL, DUMP, GETPORT and unknown */ int check_default(daemon, addr, proc, prog) char *daemon; struct sockaddr_in *addr; u_long proc; u_long prog; { if (!(from_local(addr) || good_client(daemon, addr))) { log_bad_host(addr, proc, prog); return (FALSE); } if (verboselog) log_client(addr, proc, prog); return (TRUE); } /* check_privileged_port - additional checks for privileged-port updates */ int check_privileged_port(addr, proc, prog, port) struct sockaddr_in *addr; u_long proc; u_long prog; u_long port; { #ifdef CHECK_PORT if (!legal_port(addr, port)) { log_bad_port(addr, proc, prog); return (FALSE); } #endif return (TRUE); } /* toggle_verboselog - toggle verbose logging flag */ static void toggle_verboselog(sig) int sig; { (void) signal(sig, toggle_verboselog); verboselog = !verboselog; } /* logit - report events of interest via the syslog daemon */ static void logit(severity, addr, procnum, prognum, text) int severity; struct sockaddr_in *addr; u_long procnum; u_long prognum; char *text; { char *procname; char procbuf[16 + 4 * sizeof(u_long)]; char *progname; char progbuf[16 + 4 * sizeof(u_long)]; struct rpcent *rpc; /* * Fork off a process or the portmap daemon might hang while * getrpcbynumber() or syslog() does its thing. * * Don't forget to wait for the children, too... */ if (fork() == 0) { /* Try to map program number to name. */ if (prognum == 0) { progname = ""; } else if ((rpc = getrpcbynumber((int) prognum))) { progname = rpc->r_name; } else { snprintf(progname = progbuf, sizeof (progbuf), "prog (%lu)", prognum); } /* Try to map procedure number to name. */ snprintf(procname = procbuf, sizeof (procbuf), "proc (%lu)", (u_long) procnum); /* Write syslog record. */ syslog(severity, "connect from %s to %s in %s%s", inet_ntoa(addr->sin_addr), procname, progname, text); exit(0); } }