/* net.c * Implementation of network-related stuff. * * File begun on 2007-07-20 by RGerhards (extracted from syslogd.c) * This file is under development and has not yet arrived at being fully * self-contained and a real object. So far, it is mostly an excerpt * of the "old" message code without any modifications. However, it * helps to have things at the right place one we go to the meat of it. * * Copyright 2007 Rainer Gerhards and Adiscon GmbH. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * A copy of the GPL can be found in the file "COPYING" in this distribution. */ #include "config.h" #ifdef SYSLOG_INET #include "rsyslog.h" #include #include #include #include #include #include #include #include #include #include "syslogd.h" #include "syslogd-types.h" #include "net.h" /* The following #ifdef sequence is a small compatibility * layer. It tries to work around the different availality * levels of SO_BSDCOMPAT on linuxes... * I borrowed this code from * http://www.erlang.org/ml-archive/erlang-questions/200307/msg00037.html * It still needs to be a bit better adapted to rsyslog. * rgerhards 2005-09-19 */ #ifndef BSD #include int should_use_so_bsdcompat(void) { static int init_done; static int so_bsdcompat_is_obsolete; if (!init_done) { struct utsname utsname; unsigned int version, patchlevel; init_done = 1; if (uname(&utsname) < 0) { char errStr[1024]; dbgprintf("uname: %s\r\n", strerror_r(errno, errStr, sizeof(errStr))); return 1; } /* Format is .. where the first three are unsigned integers and the last is an arbitrary string. We only care about the first two. */ if (sscanf(utsname.release, "%u.%u", &version, &patchlevel) != 2) { dbgprintf("uname: unexpected release '%s'\r\n", utsname.release); return 1; } /* SO_BSCOMPAT is deprecated and triggers warnings in 2.5 kernels. It is a no-op in 2.4 but not in 2.2 kernels. */ if (version > 2 || (version == 2 && patchlevel >= 5)) so_bsdcompat_is_obsolete = 1; } return !so_bsdcompat_is_obsolete; } #else /* #ifndef BSD */ #define should_use_so_bsdcompat() 1 #endif /* #ifndef BSD */ #ifndef SO_BSDCOMPAT /* this shall prevent compiler errors due to undfined name */ #define SO_BSDCOMPAT 0 #endif /* get the hostname of the message source. This was originally in cvthname() * but has been moved out of it because of clarity and fuctional separation. * It must be provided by the socket we received the message on as well as * a NI_MAXHOST size large character buffer for the FQDN. * * Please see http://www.hmug.org/man/3/getnameinfo.php (under Caveats) * for some explanation of the code found below. We do by default not * discard message where we detected malicouos DNS PTR records. However, * there is a user-configurabel option that will tell us if * we should abort. For this, the return value tells the caller if the * message should be processed (1) or discarded (0). */ /* TODO: after the bughunt, make this function static - rgerhards, 2007-09-18 */ rsRetVal gethname(struct sockaddr_storage *f, uchar *pszHostFQDN) { DEFiRet; int error; sigset_t omask, nmask; char ip[NI_MAXHOST]; struct addrinfo hints, *res; assert(f != NULL); assert(pszHostFQDN != NULL); error = getnameinfo((struct sockaddr *)f, SALEN((struct sockaddr *)f), ip, sizeof ip, NULL, 0, NI_NUMERICHOST); if (error) { dbgprintf("Malformed from address %s\n", gai_strerror(error)); strcpy((char*) pszHostFQDN, "???"); ABORT_FINALIZE(RS_RET_INVALID_SOURCE); } if (!DisableDNS) { sigemptyset(&nmask); sigaddset(&nmask, SIGHUP); pthread_sigmask(SIG_BLOCK, &nmask, &omask); error = getnameinfo((struct sockaddr *)f, SALEN((struct sockaddr *) f), (char*)pszHostFQDN, NI_MAXHOST, NULL, 0, NI_NAMEREQD); if (error == 0) { memset (&hints, 0, sizeof (struct addrinfo)); hints.ai_flags = AI_NUMERICHOST; hints.ai_socktype = SOCK_DGRAM; /* we now do a lookup once again. This one should fail, * because we should not have obtained a non-numeric address. If * we got a numeric one, someone messed with DNS! */ if (getaddrinfo ((char*)pszHostFQDN, NULL, &hints, &res) == 0) { uchar szErrMsg[1024]; freeaddrinfo (res); /* OK, we know we have evil. The question now is what to do about * it. One the one hand, the message might probably be intended * to harm us. On the other hand, losing the message may also harm us. * Thus, the behaviour is controlled by the $DropMsgsWithMaliciousDnsPTRRecords * option. If it tells us we should discard, we do so, else we proceed, * but log an error message together with it. * time being, we simply drop the name we obtained and use the IP - that one * is OK in any way. We do also log the error message. rgerhards, 2007-07-16 */ if(bDropMalPTRMsgs == 1) { snprintf((char*)szErrMsg, sizeof(szErrMsg) / sizeof(uchar), "Malicious PTR record, message dropped " "IP = \"%s\" HOST = \"%s\"", ip, pszHostFQDN); logerror((char*)szErrMsg); pthread_sigmask(SIG_SETMASK, &omask, NULL); ABORT_FINALIZE(RS_RET_MALICIOUS_ENTITY); } /* Please note: we deal with a malicous entry. Thus, we have crafted * the snprintf() below so that all text is in front of the entry - maybe * it contains characters that make the message unreadable * (OK, I admit this is more or less impossible, but I am paranoid...) * rgerhards, 2007-07-16 */ snprintf((char*)szErrMsg, sizeof(szErrMsg) / sizeof(uchar), "Malicious PTR record (message accepted, but used IP " "instead of PTR name: IP = \"%s\" HOST = \"%s\"", ip, pszHostFQDN); logerror((char*)szErrMsg); error = 1; /* that will trigger using IP address below. */ } } pthread_sigmask(SIG_SETMASK, &omask, NULL); } if (error || DisableDNS) { dbgprintf("Host name for your address (%s) unknown\n", ip); strcpy((char*) pszHostFQDN, ip); ABORT_FINALIZE(RS_RET_ADDRESS_UNKNOWN); } finalize_it: return iRet; } /* Return a printable representation of a host address. * Now (2007-07-16) also returns the full host name (if it could be obtained) * in the second param [thanks to mildew@gmail.com for the patch]. * The caller must provide buffer space for pszHost and pszHostFQDN. These * buffers must be of size NI_MAXHOST. This is not checked here, because * there is no way to check it. We use this way of doing things because it * frees us from using dynamic memory allocation where it really does not * pay. */ rsRetVal cvthname(struct sockaddr_storage *f, uchar *pszHost, uchar *pszHostFQDN) { DEFiRet; register uchar *p; int count; assert(f != NULL); assert(pszHost != NULL); assert(pszHostFQDN != NULL); iRet = gethname(f, pszHostFQDN); if(iRet == RS_RET_INVALID_SOURCE || iRet == RS_RET_ADDRESS_UNKNOWN) { strcpy((char*) pszHost, (char*) pszHostFQDN); /* we use whatever was provided as replacement */ ABORT_FINALIZE(RS_RET_OK); /* this is handled, we are happy with it */ } else if(iRet != RS_RET_OK) { FINALIZE; /* we return whatever error state we have - can not handle it */ } /* if we reach this point, we obtained a non-numeric hostname and can now process it */ /* Convert to lower case, just like LocalDomain above */ for (p = pszHostFQDN ; *p ; p++) if (isupper((int) *p)) *p = tolower(*p); /* OK, the fqdn is now known. Now it is time to extract only the hostname * part if we were instructed to do so. */ /* TODO: quick and dirty right now: we need to optimize that. We simply * copy over the buffer and then use the old code. In the long term, that should * be placed in its own function and probably outside of the net module (at least * if should no longer reley on syslogd.c's global config-setting variables). * Note that the old code always removes the local domain. We may want to * make this in option in the long term. (rgerhards, 2007-09-11) */ strcpy((char*)pszHost, (char*)pszHostFQDN); if ((p = (uchar*) strchr((char*)pszHost, '.'))) { /* find start of domain name "machine.example.com" */ if(strcmp((char*) (p + 1), LocalDomain) == 0) { *p = '\0'; /* simply terminate the string */ } else { /* now check if we belong to any of the domain names that were specified * in the -s command line option. If so, remove and we are done. */ if (StripDomains) { count=0; while (StripDomains[count]) { if (strcmp((char*)(p + 1), StripDomains[count]) == 0) { *p = '\0'; FINALIZE; /* we are done */ } count++; } } /* if we reach this point, we have not found any domain we should strip. Now * we try and see if the host itself is listed in the -l command line option * and so should be stripped also. If so, we do it and return. Please note that * -l list FQDNs, not just the hostname part. If it did just list the hostname, the * door would be wide-open for all kinds of mixing up of hosts. Because of this, * you'll see comparison against the full string (pszHost) below. The termination * still occurs at *p, which points at the first dot after the hostname. */ if (LocalHosts) { count=0; while (LocalHosts[count]) { if (!strcmp((char*)pszHost, LocalHosts[count])) { *p = '\0'; break; /* we are done */ } count++; } } } } finalize_it: return iRet; } #endif /* #ifdef SYSLOG_INET */ /* * vi:set ai: */