--- embedaddon/dnsmasq/src/rfc1035.c 2016/11/02 09:57:01 1.1.1.3 +++ embedaddon/dnsmasq/src/rfc1035.c 2021/03/17 00:56:46 1.1.1.4 @@ -1,4 +1,4 @@ -/* dnsmasq is Copyright (c) 2000-2016 Simon Kelley +/* dnsmasq is Copyright (c) 2000-2021 Simon Kelley 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 @@ -36,8 +36,8 @@ int extract_name(struct dns_header *header, size_t ple if ((l = *p++) == 0) /* end marker */ { - /* check that there are the correct no of bytes after the name */ - if (!CHECK_LEN(header, p, plen, extrabytes)) + /* check that there are the correct no. of bytes after the name */ + if (!CHECK_LEN(header, p1 ? p1 : p, plen, extrabytes)) return 0; if (isExtract) @@ -143,7 +143,7 @@ int extract_name(struct dns_header *header, size_t ple /* Max size of input string (for IPv6) is 75 chars.) */ #define MAXARPANAME 75 -int in_arpa_name_2_addr(char *namein, struct all_addr *addrp) +int in_arpa_name_2_addr(char *namein, union all_addr *addrp) { int j; char name[MAXARPANAME+1], *cp1; @@ -153,10 +153,10 @@ int in_arpa_name_2_addr(char *namein, struct all_addr if (strlen(namein) > MAXARPANAME) return 0; - memset(addrp, 0, sizeof(struct all_addr)); + memset(addrp, 0, sizeof(union all_addr)); /* turn name into a series of asciiz strings */ - /* j counts no of labels */ + /* j counts no. of labels */ for(j = 1,cp1 = name; *namein; cp1++, namein++) if (*namein == '.') { @@ -176,7 +176,7 @@ int in_arpa_name_2_addr(char *namein, struct all_addr if (hostname_isequal(lastchunk, "arpa") && hostname_isequal(penchunk, "in-addr")) { /* IP v4 */ - /* address arives as a name of the form + /* address arrives as a name of the form www.xxx.yyy.zzz.in-addr.arpa some of the low order address octets might be missing and should be set to zero. */ @@ -198,7 +198,6 @@ int in_arpa_name_2_addr(char *namein, struct all_addr return F_IPV4; } -#ifdef HAVE_IPV6 else if (hostname_isequal(penchunk, "ip6") && (hostname_isequal(lastchunk, "int") || hostname_isequal(lastchunk, "arpa"))) { @@ -206,7 +205,7 @@ int in_arpa_name_2_addr(char *namein, struct all_addr Address arrives as 0.1.2.3.4.5.6.7.8.9.a.b.c.d.e.f.ip6.[int|arpa] or \[xfedcba9876543210fedcba9876543210/128].ip6.[int|arpa] - Note that most of these the various reprentations are obsolete and + Note that most of these the various representations are obsolete and left-over from the many DNS-for-IPv6 wars. We support all the formats that we can since there is no reason not to. */ @@ -235,7 +234,7 @@ int in_arpa_name_2_addr(char *namein, struct all_addr if (*(cp1+1) || !isxdigit((unsigned char)*cp1)) return 0; - for (j = sizeof(struct all_addr)-1; j>0; j--) + for (j = sizeof(struct in6_addr)-1; j>0; j--) addr[j] = (addr[j] >> 4) | (addr[j-1] << 4); addr[0] = (addr[0] >> 4) | (strtol(cp1, NULL, 16) << 4); } @@ -243,7 +242,6 @@ int in_arpa_name_2_addr(char *namein, struct all_addr return F_IPV6; } } -#endif return 0; } @@ -335,55 +333,6 @@ unsigned char *skip_section(unsigned char *ansp, int c return ansp; } -/* CRC the question section. This is used to safely detect query - retransmision and to detect answers to questions we didn't ask, which - might be poisoning attacks. Note that we decode the name rather - than CRC the raw bytes, since replies might be compressed differently. - We ignore case in the names for the same reason. Return all-ones - if there is not question section. */ -#ifndef HAVE_DNSSEC -unsigned int questions_crc(struct dns_header *header, size_t plen, char *name) -{ - int q; - unsigned int crc = 0xffffffff; - unsigned char *p1, *p = (unsigned char *)(header+1); - - for (q = ntohs(header->qdcount); q != 0; q--) - { - if (!extract_name(header, plen, &p, name, 1, 4)) - return crc; /* bad packet */ - - for (p1 = (unsigned char *)name; *p1; p1++) - { - int i = 8; - char c = *p1; - - if (c >= 'A' && c <= 'Z') - c += 'a' - 'A'; - - crc ^= c << 24; - while (i--) - crc = crc & 0x80000000 ? (crc << 1) ^ 0x04c11db7 : crc << 1; - } - - /* CRC the class and type as well */ - for (p1 = p; p1 < p+4; p1++) - { - int i = 8; - crc ^= *p1 << 24; - while (i--) - crc = crc & 0x80000000 ? (crc << 1) ^ 0x04c11db7 : crc << 1; - } - - p += 4; - if (!CHECK_LEN(header, p, plen, 0)) - return crc; /* bad packet */ - } - - return crc; -} -#endif - size_t resize_packet(struct dns_header *header, size_t plen, unsigned char *pheader, size_t hlen) { unsigned char *ansp = skip_questions(header, plen); @@ -426,6 +375,16 @@ int private_net(struct in_addr addr, int ban_localhost ((ip_addr & 0xFFFFFFFF) == 0xFFFFFFFF) /* 255.255.255.255/32 (broadcast)*/ ; } +static int private_net6(struct in6_addr *a) +{ + return + IN6_IS_ADDR_UNSPECIFIED(a) || /* RFC 6303 4.3 */ + IN6_IS_ADDR_LOOPBACK(a) || /* RFC 6303 4.3 */ + IN6_IS_ADDR_LINKLOCAL(a) || /* RFC 6303 4.5 */ + ((unsigned char *)a)[0] == 0xfd || /* RFC 6303 4.4 */ + ((u32 *)a)[0] == htonl(0x20010db8); /* RFC 6303 4.6 */ +} + static unsigned char *do_doctor(unsigned char *p, int count, struct dns_header *header, size_t qlen, char *name, int *doctored) { int i, qtype, qclass, rdlen; @@ -485,6 +444,8 @@ static unsigned char *do_doctor(unsigned char *p, int { unsigned int i, len = *p1; unsigned char *p2 = p1; + if ((p1 + len - p) >= rdlen) + return 0; /* bad packet */ /* make counted string zero-term and sanitise */ for (i = 0; i < len; i++) { @@ -569,17 +530,19 @@ static int find_soa(struct dns_header *header, size_t expired and cleaned out that way. Return 1 if we reject an address because it look like part of dns-rebinding attack. */ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t now, - char **ipsets, int is_sign, int check_rebind, int no_cache_dnssec, int secure, int *doctored) + char **ipsets, int is_sign, int check_rebind, int no_cache_dnssec, + int secure, int *doctored) { unsigned char *p, *p1, *endrr, *namep; int i, j, qtype, qclass, aqtype, aqclass, ardlen, res, searched_soa = 0; unsigned long ttl = 0; - struct all_addr addr; + union all_addr addr; #ifdef HAVE_IPSET char **ipsets_cur; #else (void)ipsets; /* unused */ #endif + cache_start_insert(); @@ -588,10 +551,18 @@ int extract_addresses(struct dns_header *header, size_ { searched_soa = 1; ttl = find_soa(header, qlen, name, doctored); + + if (*doctored) + { + if (secure) + return 0; #ifdef HAVE_DNSSEC - if (*doctored && secure) - return 0; + if (option_bool(OPT_DNSSEC_VALID)) + for (i = 0; i < ntohs(header->ancount); i++) + if (daemon->rr_status[i] != 0) + return 0; #endif + } } /* go through the questions. */ @@ -602,7 +573,9 @@ int extract_addresses(struct dns_header *header, size_ int found = 0, cname_count = CNAME_CHAIN; struct crec *cpp = NULL; int flags = RCODE(header) == NXDOMAIN ? F_NXDOMAIN : 0; - int secflag = secure ? F_DNSSECOK : 0; +#ifdef HAVE_DNSSEC + int cname_short = 0; +#endif unsigned long cttl = ULONG_MAX, attl; namep = p; @@ -630,8 +603,9 @@ int extract_addresses(struct dns_header *header, size_ if (!(p1 = skip_questions(header, qlen))) return 0; - for (j = ntohs(header->ancount); j != 0; j--) + for (j = 0; j < ntohs(header->ancount); j++) { + int secflag = 0; unsigned char *tmp = namep; /* the loop body overwrites the original name, so get it back here. */ if (!extract_name(header, qlen, &tmp, name, 1, 0) || @@ -657,15 +631,31 @@ int extract_addresses(struct dns_header *header, size_ { if (!extract_name(header, qlen, &p1, name, 1, 0)) return 0; - +#ifdef HAVE_DNSSEC + if (option_bool(OPT_DNSSEC_VALID) && daemon->rr_status[j] != 0) + { + /* validated RR anywhere in CNAME chain, don't cache. */ + if (cname_short || aqtype == T_CNAME) + return 0; + + secflag = F_DNSSECOK; + /* limit TTL based on signature. */ + if (daemon->rr_status[j] < cttl) + cttl = daemon->rr_status[j]; + } +#endif + if (aqtype == T_CNAME) { - if (!cname_count-- || secure) - return 0; /* looped CNAMES, or DNSSEC, which we can't cache. */ + if (!cname_count--) + return 0; /* looped CNAMES, we can't cache. */ +#ifdef HAVE_DNSSEC + cname_short = 1; +#endif goto cname_loop; } - cache_insert(name, &addr, now, cttl, name_encoding | secflag | F_REVERSE); + cache_insert(name, &addr, C_IN, now, cttl, name_encoding | secflag | F_REVERSE); found = 1; } @@ -683,36 +673,38 @@ int extract_addresses(struct dns_header *header, size_ ttl = find_soa(header, qlen, NULL, doctored); } if (ttl) - cache_insert(NULL, &addr, now, ttl, name_encoding | F_REVERSE | F_NEG | flags | secflag); + cache_insert(NULL, &addr, C_IN, now, ttl, name_encoding | F_REVERSE | F_NEG | flags | (secure ? F_DNSSECOK : 0)); } } else { /* everything other than PTR */ struct crec *newc; - int addrlen; + int addrlen = 0; if (qtype == T_A) { addrlen = INADDRSZ; flags |= F_IPV4; } -#ifdef HAVE_IPV6 else if (qtype == T_AAAA) { addrlen = IN6ADDRSZ; flags |= F_IPV6; } -#endif - else + else if (qtype == T_SRV) + flags |= F_SRV; + else continue; cname_loop1: if (!(p1 = skip_questions(header, qlen))) return 0; - for (j = ntohs(header->ancount); j != 0; j--) + for (j = 0; j < ntohs(header->ancount); j++) { + int secflag = 0; + if (!(res = extract_name(header, qlen, &p1, name, 0, 10))) return 0; /* bad packet */ @@ -729,18 +721,28 @@ int extract_addresses(struct dns_header *header, size_ if (aqclass == C_IN && res != 2 && (aqtype == T_CNAME || aqtype == qtype)) { +#ifdef HAVE_DNSSEC + if (option_bool(OPT_DNSSEC_VALID) && daemon->rr_status[j] != 0) + { + secflag = F_DNSSECOK; + + /* limit TTl based on sig. */ + if (daemon->rr_status[j] < attl) + attl = daemon->rr_status[j]; + } +#endif if (aqtype == T_CNAME) { if (!cname_count--) return 0; /* looped CNAMES */ - newc = cache_insert(name, NULL, now, attl, F_CNAME | F_FORWARD | secflag); - if (newc) + + if ((newc = cache_insert(name, NULL, C_IN, now, attl, F_CNAME | F_FORWARD | secflag))) { newc->addr.cname.target.cache = NULL; - /* anything other than zero, to avoid being mistaken for CNAME to interface-name */ - newc->addr.cname.uid = 1; + newc->addr.cname.is_name_ptr = 0; if (cpp) { + next_uid(newc); cpp->addr.cname.target.cache = newc; cpp->addr.cname.uid = newc->uid; } @@ -750,53 +752,90 @@ int extract_addresses(struct dns_header *header, size_ if (attl < cttl) cttl = attl; + namep = p1; if (!extract_name(header, qlen, &p1, name, 1, 0)) return 0; + goto cname_loop1; } else if (!(flags & F_NXDOMAIN)) { found = 1; - /* copy address into aligned storage */ - if (!CHECK_LEN(header, p1, qlen, addrlen)) - return 0; /* bad packet */ - memcpy(&addr, p1, addrlen); - - /* check for returned address in private space */ - if (check_rebind) + if (flags & F_SRV) { - if ((flags & F_IPV4) && - private_net(addr.addr.addr4, !option_bool(OPT_LOCAL_REBIND))) - return 1; - -#ifdef HAVE_IPV6 - if ((flags & F_IPV6) && - IN6_IS_ADDR_V4MAPPED(&addr.addr.addr6)) + unsigned char *tmp = namep; + + if (!CHECK_LEN(header, p1, qlen, 6)) + return 0; /* bad packet */ + GETSHORT(addr.srv.priority, p1); + GETSHORT(addr.srv.weight, p1); + GETSHORT(addr.srv.srvport, p1); + if (!extract_name(header, qlen, &p1, name, 1, 0)) + return 0; + addr.srv.targetlen = strlen(name) + 1; /* include terminating zero */ + if (!(addr.srv.target = blockdata_alloc(name, addr.srv.targetlen))) + return 0; + + /* we overwrote the original name, so get it back here. */ + if (!extract_name(header, qlen, &tmp, name, 1, 0)) + return 0; + } + else + { + /* copy address into aligned storage */ + if (!CHECK_LEN(header, p1, qlen, addrlen)) + return 0; /* bad packet */ + memcpy(&addr, p1, addrlen); + + /* check for returned address in private space */ + if (check_rebind) { - struct in_addr v4; - v4.s_addr = ((const uint32_t *) (&addr.addr.addr6))[3]; - if (private_net(v4, !option_bool(OPT_LOCAL_REBIND))) + if ((flags & F_IPV4) && + private_net(addr.addr4, !option_bool(OPT_LOCAL_REBIND))) return 1; + + /* Block IPv4-mapped IPv6 addresses in private IPv4 address space */ + if (flags & F_IPV6) + { + if (IN6_IS_ADDR_V4MAPPED(&addr.addr6)) + { + struct in_addr v4; + v4.s_addr = ((const uint32_t *) (&addr.addr6))[3]; + if (private_net(v4, !option_bool(OPT_LOCAL_REBIND))) + return 1; + } + + /* Check for link-local (LL) and site-local (ULA) IPv6 addresses */ + if (IN6_IS_ADDR_LINKLOCAL(&addr.addr6) || + IN6_IS_ADDR_SITELOCAL(&addr.addr6)) + return 1; + + /* Check for the IPv6 loopback address (::1) when + option rebind-localhost-ok is NOT set */ + if (!option_bool(OPT_LOCAL_REBIND) && + IN6_IS_ADDR_LOOPBACK(&addr.addr6)) + return 1; + } } -#endif - } - + #ifdef HAVE_IPSET - if (ipsets && (flags & (F_IPV4 | F_IPV6))) - { - ipsets_cur = ipsets; - while (*ipsets_cur) + if (ipsets && (flags & (F_IPV4 | F_IPV6))) { - log_query((flags & (F_IPV4 | F_IPV6)) | F_IPSET, name, &addr, *ipsets_cur); - add_to_ipset(*ipsets_cur++, &addr, flags, 0); + ipsets_cur = ipsets; + while (*ipsets_cur) + { + log_query((flags & (F_IPV4 | F_IPV6)) | F_IPSET, name, &addr, *ipsets_cur); + add_to_ipset(*ipsets_cur++, &addr, flags, 0); + } } - } #endif + } - newc = cache_insert(name, &addr, now, attl, flags | F_FORWARD | secflag); + newc = cache_insert(name, &addr, C_IN, now, attl, flags | F_FORWARD | secflag); if (newc && cpp) { + next_uid(newc); cpp->addr.cname.target.cache = newc; cpp->addr.cname.uid = newc->uid; } @@ -820,9 +859,10 @@ int extract_addresses(struct dns_header *header, size_ pointing at this, inherit its TTL */ if (ttl || cpp) { - newc = cache_insert(name, NULL, now, ttl ? ttl : cttl, F_FORWARD | F_NEG | flags | secflag); + newc = cache_insert(name, NULL, C_IN, now, ttl ? ttl : cttl, F_FORWARD | F_NEG | flags | (secure ? F_DNSSECOK : 0)); if (newc && cpp) { + next_uid(newc); cpp->addr.cname.target.cache = newc; cpp->addr.cname.uid = newc->uid; } @@ -875,23 +915,29 @@ unsigned int extract_request(struct dns_header *header if (qtype == T_ANY) return F_IPV4 | F_IPV6; } + + /* F_DNSSECOK as agument to search_servers() inhibits forwarding + to servers for domains without a trust anchor. This make the + behaviour for DS and DNSKEY queries we forward the same + as for DS and DNSKEY queries we originate. */ + if (qtype == T_DS || qtype == T_DNSKEY) + return F_DNSSECOK; return F_QUERY; } - size_t setup_reply(struct dns_header *header, size_t qlen, - struct all_addr *addrp, unsigned int flags, unsigned long ttl) + union all_addr *addrp, unsigned int flags, unsigned long ttl) { unsigned char *p; - + if (!(p = skip_questions(header, qlen))) return 0; /* clear authoritative and truncated flags, set QR flag */ - header->hb3 = (header->hb3 & ~(HB3_AA | HB3_TC)) | HB3_QR; - /* set RA flag */ - header->hb4 |= HB4_RA; + header->hb3 = (header->hb3 & ~(HB3_AA | HB3_TC )) | HB3_QR; + /* clear AD flag, set RA flag */ + header->hb4 = (header->hb4 & ~HB4_AD) | HB4_RA; header->nscount = htons(0); header->arcount = htons(0); @@ -900,65 +946,74 @@ size_t setup_reply(struct dns_header *header, size_t q SET_RCODE(header, NOERROR); /* empty domain */ else if (flags == F_NXDOMAIN) SET_RCODE(header, NXDOMAIN); - else if (flags == F_IPV4) - { /* we know the address */ - SET_RCODE(header, NOERROR); - header->ancount = htons(1); - header->hb3 |= HB3_AA; - add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_A, C_IN, "4", addrp); + else if (flags == F_SERVFAIL) + { + union all_addr a; + a.log.rcode = SERVFAIL; + log_query(F_CONFIG | F_RCODE, "error", &a, NULL); + SET_RCODE(header, SERVFAIL); } -#ifdef HAVE_IPV6 - else if (flags == F_IPV6) + else if (flags & ( F_IPV4 | F_IPV6)) { - SET_RCODE(header, NOERROR); - header->ancount = htons(1); - header->hb3 |= HB3_AA; - add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_AAAA, C_IN, "6", addrp); + if (flags & F_IPV4) + { /* we know the address */ + SET_RCODE(header, NOERROR); + header->ancount = htons(1); + header->hb3 |= HB3_AA; + add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_A, C_IN, "4", addrp); + } + + if (flags & F_IPV6) + { + SET_RCODE(header, NOERROR); + header->ancount = htons(ntohs(header->ancount) + 1); + header->hb3 |= HB3_AA; + add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_AAAA, C_IN, "6", addrp); + } } -#endif else /* nowhere to forward to */ - SET_RCODE(header, REFUSED); - + { + union all_addr a; + a.log.rcode = REFUSED; + log_query(F_CONFIG | F_RCODE, "error", &a, NULL); + SET_RCODE(header, REFUSED); + } + return p - (unsigned char *)header; } /* check if name matches local names ie from /etc/hosts or DHCP or local mx names. */ int check_for_local_domain(char *name, time_t now) { - struct crec *crecp; struct mx_srv_record *mx; struct txt_record *txt; struct interface_name *intr; struct ptr_record *ptr; struct naptr *naptr; - /* Note: the call to cache_find_by_name is intended to find any record which matches - ie A, AAAA, CNAME. */ - - if ((crecp = cache_find_by_name(NULL, name, now, F_IPV4 | F_IPV6 | F_CNAME |F_NO_RR)) && - (crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG))) - return 1; - for (naptr = daemon->naptr; naptr; naptr = naptr->next) - if (hostname_isequal(name, naptr->name)) + if (hostname_issubdomain(name, naptr->name)) return 1; for (mx = daemon->mxnames; mx; mx = mx->next) - if (hostname_isequal(name, mx->name)) + if (hostname_issubdomain(name, mx->name)) return 1; for (txt = daemon->txt; txt; txt = txt->next) - if (hostname_isequal(name, txt->name)) + if (hostname_issubdomain(name, txt->name)) return 1; for (intr = daemon->int_names; intr; intr = intr->next) - if (hostname_isequal(name, intr->name)) + if (hostname_issubdomain(name, intr->name)) return 1; for (ptr = daemon->ptr; ptr; ptr = ptr->next) - if (hostname_isequal(name, ptr->name)) + if (hostname_issubdomain(name, ptr->name)) return 1; - + + if (cache_find_non_terminal(name, now)) + return 1; + return 0; } @@ -998,7 +1053,7 @@ int check_for_bogus_wildcard(struct dns_header *header /* Found a bogus address. Insert that info here, since there no SOA record to get the ttl from in the normal processing */ cache_start_insert(); - cache_insert(name, NULL, now, ttl, F_IPV4 | F_FORWARD | F_NEG | F_NXDOMAIN); + cache_insert(name, NULL, C_IN, now, ttl, F_IPV4 | F_FORWARD | F_NEG | F_NXDOMAIN); cache_end_insert(); return 1; @@ -1049,6 +1104,7 @@ int check_for_ignored_address(struct dns_header *heade return 0; } + int add_resource_record(struct dns_header *header, char *limit, int *truncp, int nameoffset, unsigned char **pp, unsigned long ttl, int *offset, unsigned short type, unsigned short class, char *format, ...) { @@ -1058,29 +1114,41 @@ int add_resource_record(struct dns_header *header, cha unsigned short usval; long lval; char *sval; + +#define CHECK_LIMIT(size) \ + if (limit && p + (size) > (unsigned char*)limit) goto truncated; - if (truncp && *truncp) - return 0; - va_start(ap, format); /* make ap point to 1st unamed argument */ + if (truncp && *truncp) + goto truncated; + if (nameoffset > 0) { + CHECK_LIMIT(2); PUTSHORT(nameoffset | 0xc000, p); } else { char *name = va_arg(ap, char *); - if (name) - p = do_rfc1035_name(p, name); + if (name && !(p = do_rfc1035_name(p, name, limit))) + goto truncated; + if (nameoffset < 0) { + CHECK_LIMIT(2); PUTSHORT(-nameoffset | 0xc000, p); } else - *p++ = 0; + { + CHECK_LIMIT(1); + *p++ = 0; + } } + /* type (2) + class (2) + ttl (4) + rdlen (2) */ + CHECK_LIMIT(10); + PUTSHORT(type, p); PUTSHORT(class, p); PUTLONG(ttl, p); /* TTL */ @@ -1091,45 +1159,51 @@ int add_resource_record(struct dns_header *header, cha for (; *format; format++) switch (*format) { -#ifdef HAVE_IPV6 case '6': + CHECK_LIMIT(IN6ADDRSZ); sval = va_arg(ap, char *); memcpy(p, sval, IN6ADDRSZ); p += IN6ADDRSZ; break; -#endif case '4': + CHECK_LIMIT(INADDRSZ); sval = va_arg(ap, char *); memcpy(p, sval, INADDRSZ); p += INADDRSZ; break; case 'b': + CHECK_LIMIT(1); usval = va_arg(ap, int); *p++ = usval; break; case 's': + CHECK_LIMIT(2); usval = va_arg(ap, int); PUTSHORT(usval, p); break; case 'l': + CHECK_LIMIT(4); lval = va_arg(ap, long); PUTLONG(lval, p); break; case 'd': - /* get domain-name answer arg and store it in RDATA field */ - if (offset) - *offset = p - (unsigned char *)header; - p = do_rfc1035_name(p, va_arg(ap, char *)); - *p++ = 0; + /* get domain-name answer arg and store it in RDATA field */ + if (offset) + *offset = p - (unsigned char *)header; + if (!(p = do_rfc1035_name(p, va_arg(ap, char *), limit))) + goto truncated; + CHECK_LIMIT(1); + *p++ = 0; break; case 't': usval = va_arg(ap, int); + CHECK_LIMIT(usval); sval = va_arg(ap, char *); if (usval != 0) memcpy(p, sval, usval); @@ -1141,6 +1215,7 @@ int add_resource_record(struct dns_header *header, cha usval = sval ? strlen(sval) : 0; if (usval > 255) usval = 255; + CHECK_LIMIT(usval + 1); *p++ = (unsigned char)usval; memcpy(p, sval, usval); p += usval; @@ -1149,19 +1224,20 @@ int add_resource_record(struct dns_header *header, cha va_end(ap); /* clean up variable argument pointer */ + /* Now, store real RDLength. sav already checked against limit. */ j = p - sav - 2; - PUTSHORT(j, sav); /* Now, store real RDLength */ + PUTSHORT(j, sav); - /* check for overflow of buffer */ - if (limit && ((unsigned char *)limit - p) < 0) - { - if (truncp) - *truncp = 1; - return 0; - } - *pp = p; return 1; + + truncated: + va_end(ap); + if (truncp) + *truncp = 1; + return 0; + +#undef CHECK_LIMIT } static unsigned long crec_ttl(struct crec *crecp, time_t now) @@ -1184,14 +1260,18 @@ static unsigned long crec_ttl(struct crec *crecp, time if (crecp->flags & F_IMMORTAL) return crecp->ttd; - /* Return the Max TTL value if it is lower then the actual TTL */ + /* Return the Max TTL value if it is lower than the actual TTL */ if (daemon->max_ttl == 0 || ((unsigned)(crecp->ttd - now) < daemon->max_ttl)) return crecp->ttd - now; else return daemon->max_ttl; } - +static int cache_validated(const struct crec *crecp) +{ + return (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK)); +} + /* return zero if we can't answer from cache, or packet size if we can */ size_t answer_request(struct dns_header *header, char *limit, size_t qlen, struct in_addr local_addr, struct in_addr local_netmask, @@ -1200,22 +1280,24 @@ size_t answer_request(struct dns_header *header, char char *name = daemon->namebuff; unsigned char *p, *ansp; unsigned int qtype, qclass; - struct all_addr addr; + union all_addr addr; int nameoffset; unsigned short flag; int q, ans, anscount = 0, addncount = 0; int dryrun = 0; struct crec *crecp; - int nxdomain = 0, auth = 1, trunc = 0, sec_data = 1; + int nxdomain = 0, notimp = 0, auth = 1, trunc = 0, sec_data = 1; struct mx_srv_record *rec; size_t len; - + int rd_bit = (header->hb3 & HB3_RD); + + /* never answer queries with RD unset, to avoid cache snooping. */ if (ntohs(header->ancount) != 0 || ntohs(header->nscount) != 0 || - ntohs(header->qdcount) == 0 || + ntohs(header->qdcount) == 0 || OPCODE(header) != QUERY ) return 0; - + /* Don't return AD set if checking disabled. */ if (header->hb4 & HB4_CD) sec_data = 0; @@ -1239,6 +1321,8 @@ size_t answer_request(struct dns_header *header, char for (q = ntohs(header->qdcount); q != 0; q--) { + int count = 255; /* catch loops */ + /* save pointer to name for copying into answers */ nameoffset = p - (unsigned char *)header; @@ -1250,7 +1334,37 @@ size_t answer_request(struct dns_header *header, char GETSHORT(qclass, p); ans = 0; /* have we answered this question */ - + + while (--count != 0 && (crecp = cache_find_by_name(NULL, name, now, F_CNAME))) + { + char *cname_target = cache_get_cname_target(crecp); + + /* If the client asked for DNSSEC don't use cached data. */ + if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || + (rd_bit && (!do_bit || cache_validated(crecp)))) + { + if (crecp->flags & F_CONFIG || qtype == T_CNAME) + ans = 1; + + if (!(crecp->flags & F_DNSSECOK)) + sec_data = 0; + + if (!dryrun) + { + log_query(crecp->flags, name, NULL, record_source(crecp->uid)); + if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, + crec_ttl(crecp, now), &nameoffset, + T_CNAME, C_IN, "d", cname_target)) + anscount++; + } + + } + else + return 0; /* give up if any cached CNAME in chain can't be used for DNSSEC reasons. */ + + strcpy(name, cname_target); + } + if (qtype == T_TXT || qtype == T_ANY) { struct txt_record *t; @@ -1258,12 +1372,12 @@ size_t answer_request(struct dns_header *header, char { if (t->class == qclass && hostname_isequal(name, t->name)) { - ans = 1; + ans = 1, sec_data = 0; if (!dryrun) { unsigned long ttl = daemon->local_ttl; int ok = 1; - log_query(F_CONFIG | F_RRNAME, name, NULL, ""); +#ifndef NO_ID /* Dynamically generate stat record */ if (t->stat != 0) { @@ -1271,13 +1385,34 @@ size_t answer_request(struct dns_header *header, char if (!cache_make_stat(t)) ok = 0; } - - if (ok && add_resource_record(header, limit, &trunc, nameoffset, &ansp, - ttl, NULL, - T_TXT, t->class, "t", t->len, t->txt)) - anscount++; +#endif + if (ok) + { + log_query(F_CONFIG | F_RRNAME, name, NULL, ""); + if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, + ttl, NULL, + T_TXT, t->class, "t", t->len, t->txt)) + anscount++; + } + } + } + } + } + if (qclass == C_CHAOS) + { + /* don't forward *.bind and *.server chaos queries - always reply with NOTIMP */ + if (hostname_issubdomain("bind", name) || hostname_issubdomain("server", name)) + { + if (!ans) + { + notimp = 1, auth = 0; + if (!dryrun) + { + addr.log.rcode = NOTIMP; + log_query(F_CONFIG | F_RCODE, name, &addr, NULL); } + ans = 1, sec_data = 0; } } } @@ -1293,11 +1428,11 @@ size_t answer_request(struct dns_header *header, char sec_data = 0; if (!dryrun) { - log_query(F_CONFIG | F_RRNAME, name, NULL, ""); + log_query(F_CONFIG | F_RRNAME, name, NULL, querystr(NULL, t->class)); if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, NULL, t->class, C_IN, "t", t->len, t->txt)) - anscount ++; + anscount++; } } @@ -1318,7 +1453,7 @@ size_t answer_request(struct dns_header *header, char struct addrlist *addrlist; for (addrlist = intr->addr; addrlist; addrlist = addrlist->next) - if (!(addrlist->flags & ADDRLIST_IPV6) && addr.addr.addr4.s_addr == addrlist->addr.addr.addr4.s_addr) + if (!(addrlist->flags & ADDRLIST_IPV6) && addr.addr4.s_addr == addrlist->addr.addr4.s_addr) break; if (addrlist) @@ -1327,14 +1462,13 @@ size_t answer_request(struct dns_header *header, char while (intr->next && strcmp(intr->intr, intr->next->intr) == 0) intr = intr->next; } -#ifdef HAVE_IPV6 else if (is_arpa == F_IPV6) for (intr = daemon->int_names; intr; intr = intr->next) { struct addrlist *addrlist; for (addrlist = intr->addr; addrlist; addrlist = addrlist->next) - if ((addrlist->flags & ADDRLIST_IPV6) && IN6_ARE_ADDR_EQUAL(&addr.addr.addr6, &addrlist->addr.addr.addr6)) + if ((addrlist->flags & ADDRLIST_IPV6) && IN6_ARE_ADDR_EQUAL(&addr.addr6, &addrlist->addr.addr6)) break; if (addrlist) @@ -1343,7 +1477,6 @@ size_t answer_request(struct dns_header *header, char while (intr->next && strcmp(intr->intr, intr->next->intr) == 0) intr = intr->next; } -#endif if (intr) { @@ -1379,9 +1512,8 @@ size_t answer_request(struct dns_header *header, char /* Don't use cache when DNSSEC data required, unless we know that the zone is unsigned, which implies that we're doing validation. */ - if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || - !do_bit || - (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK))) + if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || + (rd_bit && (!do_bit || cache_validated(crecp)) )) { do { @@ -1434,75 +1566,55 @@ size_t answer_request(struct dns_header *header, char anscount++; } } - else if (is_arpa == F_IPV4 && - option_bool(OPT_BOGUSPRIV) && - private_net(addr.addr.addr4, 1)) + else if (option_bool(OPT_BOGUSPRIV) && ( + (is_arpa == F_IPV6 && private_net6(&addr.addr6)) || + (is_arpa == F_IPV4 && private_net(addr.addr4, 1)))) { - /* if not in cache, enabled and private IPV4 address, return NXDOMAIN */ - ans = 1; - sec_data = 0; - nxdomain = 1; - if (!dryrun) - log_query(F_CONFIG | F_REVERSE | F_IPV4 | F_NEG | F_NXDOMAIN, - name, &addr, NULL); - } - } - - for (flag = F_IPV4; flag; flag = (flag == F_IPV4) ? F_IPV6 : 0) - { - unsigned short type = T_A; - struct interface_name *intr; + struct server *serv; + unsigned int namelen = strlen(name); + char *nameend = name + namelen; - if (flag == F_IPV6) -#ifdef HAVE_IPV6 - type = T_AAAA; -#else - break; -#endif - - if (qtype != type && qtype != T_ANY) - continue; - - /* Check for "A for A" queries; be rather conservative - about what looks like dotted-quad. */ - if (qtype == T_A) - { - char *cp; - unsigned int i, a; - int x; - - for (cp = name, i = 0, a = 0; *cp; i++) + /* see if have rev-server set */ + for (serv = daemon->servers; serv; serv = serv->next) { - if (!isdigit((unsigned char)*cp) || (x = strtol(cp, &cp, 10)) > 255) - { - i = 5; - break; - } - - a = (a << 8) + x; - - if (*cp == '.') - cp++; + unsigned int domainlen; + char *matchstart; + + if ((serv->flags & (SERV_HAS_DOMAIN | SERV_NO_ADDR)) != SERV_HAS_DOMAIN) + continue; + + domainlen = strlen(serv->domain); + if (domainlen == 0 || domainlen > namelen) + continue; + + matchstart = nameend - domainlen; + if (hostname_isequal(matchstart, serv->domain) && + (namelen == domainlen || *(matchstart-1) == '.' )) + break; } - - if (i == 4) + + /* if no configured server, not in cache, enabled and private IPV4 address, return NXDOMAIN */ + if (!serv) { ans = 1; sec_data = 0; + nxdomain = 1; if (!dryrun) - { - addr.addr.addr4.s_addr = htonl(a); - log_query(F_FORWARD | F_CONFIG | F_IPV4, name, &addr, NULL); - if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, - daemon->local_ttl, NULL, type, C_IN, "4", &addr)) - anscount++; - } - continue; + log_query(F_CONFIG | F_REVERSE | is_arpa | F_NEG | F_NXDOMAIN, + name, &addr, NULL); } } + } + for (flag = F_IPV4; flag; flag = (flag == F_IPV4) ? F_IPV6 : 0) + { + unsigned short type = (flag == F_IPV6) ? T_AAAA : T_A; + struct interface_name *intr; + + if (qtype != type && qtype != T_ANY) + continue; + /* interface name stuff */ - intname_restart: for (intr = daemon->int_names; intr; intr = intr->next) if (hostname_isequal(name, intr->name)) break; @@ -1510,22 +1622,36 @@ size_t answer_request(struct dns_header *header, char if (intr) { struct addrlist *addrlist; - int gotit = 0; + int gotit = 0, localise = 0; enumerate_interfaces(0); + + /* See if a putative address is on the network from which we received + the query, is so we'll filter other answers. */ + if (local_addr.s_addr != 0 && option_bool(OPT_LOCALISE) && type == T_A) + for (intr = daemon->int_names; intr; intr = intr->next) + if (hostname_isequal(name, intr->name)) + for (addrlist = intr->addr; addrlist; addrlist = addrlist->next) + if (!(addrlist->flags & ADDRLIST_IPV6) && + is_same_net(addrlist->addr.addr4, local_addr, local_netmask)) + { + localise = 1; + break; + } for (intr = daemon->int_names; intr; intr = intr->next) if (hostname_isequal(name, intr->name)) { for (addrlist = intr->addr; addrlist; addrlist = addrlist->next) -#ifdef HAVE_IPV6 if (((addrlist->flags & ADDRLIST_IPV6) ? T_AAAA : T_A) == type) -#endif { -#ifdef HAVE_IPV6 + if (localise && + !is_same_net(addrlist->addr.addr4, local_addr, local_netmask)) + continue; + if (addrlist->flags & ADDRLIST_REVONLY) continue; -#endif + ans = 1; sec_data = 0; if (!dryrun) @@ -1546,29 +1672,29 @@ size_t answer_request(struct dns_header *header, char continue; } - cname_restart: - if ((crecp = cache_find_by_name(NULL, name, now, flag | F_CNAME | (dryrun ? F_NO_RR : 0)))) + if ((crecp = cache_find_by_name(NULL, name, now, flag | (dryrun ? F_NO_RR : 0)))) { int localise = 0; - /* See if a putative address is on the network from which we recieved + /* See if a putative address is on the network from which we received the query, is so we'll filter other answers. */ if (local_addr.s_addr != 0 && option_bool(OPT_LOCALISE) && flag == F_IPV4) { struct crec *save = crecp; do { if ((crecp->flags & F_HOSTS) && - is_same_net(*((struct in_addr *)&crecp->addr), local_addr, local_netmask)) + is_same_net(crecp->addr.addr4, local_addr, local_netmask)) { localise = 1; break; } - } while ((crecp = cache_find_by_name(crecp, name, now, flag | F_CNAME))); + } while ((crecp = cache_find_by_name(crecp, name, now, flag))); crecp = save; } /* If the client asked for DNSSEC don't use cached data. */ - if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || !do_bit || !(crecp->flags & F_DNSSECOK)) + if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || + (rd_bit && (!do_bit || cache_validated(crecp)) )) do { /* don't answer wildcard queries with data not from /etc/hosts @@ -1579,27 +1705,6 @@ size_t answer_request(struct dns_header *header, char if (!(crecp->flags & F_DNSSECOK)) sec_data = 0; - if (crecp->flags & F_CNAME) - { - char *cname_target = cache_get_cname_target(crecp); - - if (!dryrun) - { - log_query(crecp->flags, name, NULL, record_source(crecp->uid)); - if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, - crec_ttl(crecp, now), &nameoffset, - T_CNAME, C_IN, "d", cname_target)) - anscount++; - } - - strcpy(name, cname_target); - /* check if target interface_name */ - if (crecp->addr.cname.uid == SRC_INTERFACE) - goto intname_restart; - else - goto cname_restart; - } - if (crecp->flags & F_NEG) { ans = 1; @@ -1615,7 +1720,7 @@ size_t answer_request(struct dns_header *header, char filter here. */ if (localise && (crecp->flags & F_HOSTS) && - !is_same_net(*((struct in_addr *)&crecp->addr), local_addr, local_netmask)) + !is_same_net(crecp->addr.addr4, local_addr, local_netmask)) continue; if (!(crecp->flags & (F_HOSTS | F_DHCP))) @@ -1624,7 +1729,7 @@ size_t answer_request(struct dns_header *header, char ans = 1; if (!dryrun) { - log_query(crecp->flags & ~F_REVERSE, name, &crecp->addr.addr, + log_query(crecp->flags & ~F_REVERSE, name, &crecp->addr, record_source(crecp->uid)); if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, @@ -1633,11 +1738,11 @@ size_t answer_request(struct dns_header *header, char anscount++; } } - } while ((crecp = cache_find_by_name(crecp, name, now, flag | F_CNAME))); + } while ((crecp = cache_find_by_name(crecp, name, now, flag))); } else if (is_name_synthetic(flag, name, &addr)) { - ans = 1; + ans = 1, sec_data = 0; if (!dryrun) { log_query(F_FORWARD | F_CONFIG | flag, name, &addr, NULL); @@ -1648,51 +1753,33 @@ size_t answer_request(struct dns_header *header, char } } - if (qtype == T_CNAME || qtype == T_ANY) - { - if ((crecp = cache_find_by_name(NULL, name, now, F_CNAME)) && - (qtype == T_CNAME || (crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG | (dryrun ? F_NO_RR : 0))))) - { - if (!(crecp->flags & F_DNSSECOK)) - sec_data = 0; - - ans = 1; - if (!dryrun) - { - log_query(crecp->flags, name, NULL, record_source(crecp->uid)); - if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, - crec_ttl(crecp, now), &nameoffset, - T_CNAME, C_IN, "d", cache_get_cname_target(crecp))) - anscount++; - } - } - } - if (qtype == T_MX || qtype == T_ANY) { int found = 0; for (rec = daemon->mxnames; rec; rec = rec->next) if (!rec->issrv && hostname_isequal(name, rec->name)) { - ans = found = 1; - if (!dryrun) - { - int offset; - log_query(F_CONFIG | F_RRNAME, name, NULL, ""); - if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, - &offset, T_MX, C_IN, "sd", rec->weight, rec->target)) - { - anscount++; - if (rec->target) - rec->offset = offset; - } - } + ans = found = 1; + sec_data = 0; + if (!dryrun) + { + int offset; + log_query(F_CONFIG | F_RRNAME, name, NULL, ""); + if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, + &offset, T_MX, C_IN, "sd", rec->weight, rec->target)) + { + anscount++; + if (rec->target) + rec->offset = offset; + } + } } - if (!found && (option_bool(OPT_SELFMX) || option_bool(OPT_LOCALMX)) && + if (!found && (option_bool(OPT_SELFMX) || option_bool(OPT_LOCALMX)) && cache_find_by_name(NULL, name, now, F_HOSTS | F_DHCP | F_NO_RR)) { ans = 1; + sec_data = 0; if (!dryrun) { log_query(F_CONFIG | F_RRNAME, name, NULL, ""); @@ -1713,6 +1800,7 @@ size_t answer_request(struct dns_header *header, char if (rec->issrv && hostname_isequal(name, rec->name)) { found = ans = 1; + sec_data = 0; if (!dryrun) { int offset; @@ -1745,10 +1833,45 @@ size_t answer_request(struct dns_header *header, char *up = move; move->next = NULL; } - + + if (!found) + { + if ((crecp = cache_find_by_name(NULL, name, now, F_SRV | (dryrun ? F_NO_RR : 0))) && + rd_bit && (!do_bit || (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK)))) + { + if (!(crecp->flags & F_DNSSECOK)) + sec_data = 0; + + auth = 0; + found = ans = 1; + + do { + if (crecp->flags & F_NEG) + { + if (crecp->flags & F_NXDOMAIN) + nxdomain = 1; + if (!dryrun) + log_query(crecp->flags, name, NULL, NULL); + } + else if (!dryrun) + { + char *target = blockdata_retrieve(crecp->addr.srv.target, crecp->addr.srv.targetlen, NULL); + log_query(crecp->flags, name, NULL, 0); + + if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, + crec_ttl(crecp, now), NULL, T_SRV, C_IN, "sssd", + crecp->addr.srv.priority, crecp->addr.srv.weight, crecp->addr.srv.srvport, + target)) + anscount++; + } + } while ((crecp = cache_find_by_name(crecp, name, now, F_SRV))); + } + } + if (!found && option_bool(OPT_FILTER) && (qtype == T_SRV || (qtype == T_ANY && strchr(name, '_')))) { ans = 1; + sec_data = 0; if (!dryrun) log_query(F_CONFIG | F_NEG, name, NULL, NULL); } @@ -1761,6 +1884,7 @@ size_t answer_request(struct dns_header *header, char if (hostname_isequal(name, na->name)) { ans = 1; + sec_data = 0; if (!dryrun) { log_query(F_CONFIG | F_RRNAME, name, NULL, ""); @@ -1773,11 +1897,12 @@ size_t answer_request(struct dns_header *header, char } if (qtype == T_MAILB) - ans = 1, nxdomain = 1; + ans = 1, nxdomain = 1, sec_data = 0; if (qtype == T_SOA && option_bool(OPT_FILTER)) { - ans = 1; + ans = 1; + sec_data = 0; if (!dryrun) log_query(F_CONFIG | F_NEG, name, &addr, NULL); } @@ -1806,11 +1931,8 @@ size_t answer_request(struct dns_header *header, char crecp = NULL; while ((crecp = cache_find_by_name(crecp, rec->target, now, F_IPV4 | F_IPV6))) { -#ifdef HAVE_IPV6 int type = crecp->flags & F_IPV4 ? T_A : T_AAAA; -#else - int type = T_A; -#endif + if (crecp->flags & F_NEG) continue; @@ -1827,7 +1949,7 @@ size_t answer_request(struct dns_header *header, char /* set RA flag */ header->hb4 |= HB4_RA; - /* authoritive - only hosts and DHCP derived names. */ + /* authoritative - only hosts and DHCP derived names. */ if (auth) header->hb3 |= HB3_AA; @@ -1837,6 +1959,8 @@ size_t answer_request(struct dns_header *header, char if (nxdomain) SET_RCODE(header, NXDOMAIN); + else if (notimp) + SET_RCODE(header, NOTIMP); else SET_RCODE(header, NOERROR); /* no error */ header->ancount = htons(anscount);