| /* dnssec.c is Copyright (c) 2012 Giovanni Bajo <rasky@develer.com> |
| and Copyright (c) 2012-2018 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 |
| the Free Software Foundation; version 2 dated June, 1991, or |
| (at your option) version 3 dated 29 June, 2007. |
| |
| 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, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include "dnsmasq.h" |
| |
| #ifdef HAVE_DNSSEC |
| |
| #define SERIAL_UNDEF -100 |
| #define SERIAL_EQ 0 |
| #define SERIAL_LT -1 |
| #define SERIAL_GT 1 |
| |
| /* Convert from presentation format to wire format, in place. |
| Also map UC -> LC. |
| Note that using extract_name to get presentation format |
| then calling to_wire() removes compression and maps case, |
| thus generating names in canonical form. |
| Calling to_wire followed by from_wire is almost an identity, |
| except that the UC remains mapped to LC. |
| |
| Note that both /000 and '.' are allowed within labels. These get |
| represented in presentation format using NAME_ESCAPE as an escape |
| character. In theory, if all the characters in a name were /000 or |
| '.' or NAME_ESCAPE then all would have to be escaped, so the |
| presentation format would be twice as long as the spec (1024). |
| The buffers are all declared as 2049 (allowing for the trailing zero) |
| for this reason. |
| */ |
| static int to_wire(char *name) |
| { |
| unsigned char *l, *p, *q, term; |
| int len; |
| |
| for (l = (unsigned char*)name; *l != 0; l = p) |
| { |
| for (p = l; *p != '.' && *p != 0; p++) |
| if (*p >= 'A' && *p <= 'Z') |
| *p = *p - 'A' + 'a'; |
| else if (*p == NAME_ESCAPE) |
| { |
| for (q = p; *q; q++) |
| *q = *(q+1); |
| (*p)--; |
| } |
| term = *p; |
| |
| if ((len = p - l) != 0) |
| memmove(l+1, l, len); |
| *l = len; |
| |
| p++; |
| |
| if (term == 0) |
| *p = 0; |
| } |
| |
| return l + 1 - (unsigned char *)name; |
| } |
| |
| /* Note: no compression allowed in input. */ |
| static void from_wire(char *name) |
| { |
| unsigned char *l, *p, *last; |
| int len; |
| |
| for (last = (unsigned char *)name; *last != 0; last += *last+1); |
| |
| for (l = (unsigned char *)name; *l != 0; l += len+1) |
| { |
| len = *l; |
| memmove(l, l+1, len); |
| for (p = l; p < l + len; p++) |
| if (*p == '.' || *p == 0 || *p == NAME_ESCAPE) |
| { |
| memmove(p+1, p, 1 + last - p); |
| len++; |
| *p++ = NAME_ESCAPE; |
| (*p)++; |
| } |
| |
| l[len] = '.'; |
| } |
| |
| if ((char *)l != name) |
| *(l-1) = 0; |
| } |
| |
| /* Input in presentation format */ |
| static int count_labels(char *name) |
| { |
| int i; |
| |
| if (*name == 0) |
| return 0; |
| |
| for (i = 0; *name; name++) |
| if (*name == '.') |
| i++; |
| |
| return i+1; |
| } |
| |
| /* Implement RFC1982 wrapped compare for 32-bit numbers */ |
| static int serial_compare_32(u32 s1, u32 s2) |
| { |
| if (s1 == s2) |
| return SERIAL_EQ; |
| |
| if ((s1 < s2 && (s2 - s1) < (1UL<<31)) || |
| (s1 > s2 && (s1 - s2) > (1UL<<31))) |
| return SERIAL_LT; |
| if ((s1 < s2 && (s2 - s1) > (1UL<<31)) || |
| (s1 > s2 && (s1 - s2) < (1UL<<31))) |
| return SERIAL_GT; |
| return SERIAL_UNDEF; |
| } |
| |
| /* Called at startup. If the timestamp file is configured and exists, put its mtime on |
| timestamp_time. If it doesn't exist, create it, and set the mtime to 1-1-2015. |
| return -1 -> Cannot create file. |
| 0 -> not using timestamp, or timestamp exists and is in past. |
| 1 -> timestamp exists and is in future. |
| */ |
| |
| static time_t timestamp_time; |
| |
| int setup_timestamp(void) |
| { |
| struct stat statbuf; |
| |
| daemon->back_to_the_future = 0; |
| |
| if (!daemon->timestamp_file) |
| return 0; |
| |
| if (stat(daemon->timestamp_file, &statbuf) != -1) |
| { |
| timestamp_time = statbuf.st_mtime; |
| check_and_exit: |
| if (difftime(timestamp_time, time(0)) <= 0) |
| { |
| /* time already OK, update timestamp, and do key checking from the start. */ |
| if (utimes(daemon->timestamp_file, NULL) == -1) |
| my_syslog(LOG_ERR, _("failed to update mtime on %s: %s"), daemon->timestamp_file, strerror(errno)); |
| daemon->back_to_the_future = 1; |
| return 0; |
| } |
| return 1; |
| } |
| |
| if (errno == ENOENT) |
| { |
| /* NB. for explanation of O_EXCL flag, see comment on pidfile in dnsmasq.c */ |
| int fd = open(daemon->timestamp_file, O_WRONLY | O_CREAT | O_NONBLOCK | O_EXCL, 0666); |
| if (fd != -1) |
| { |
| struct timeval tv[2]; |
| |
| close(fd); |
| |
| timestamp_time = 1420070400; /* 1-1-2015 */ |
| tv[0].tv_sec = tv[1].tv_sec = timestamp_time; |
| tv[0].tv_usec = tv[1].tv_usec = 0; |
| if (utimes(daemon->timestamp_file, tv) == 0) |
| goto check_and_exit; |
| } |
| } |
| |
| return -1; |
| } |
| |
| /* Check whether today/now is between date_start and date_end */ |
| static int check_date_range(u32 date_start, u32 date_end) |
| { |
| unsigned long curtime = time(0); |
| |
| /* Checking timestamps may be temporarily disabled */ |
| |
| /* If the current time if _before_ the timestamp |
| on our persistent timestamp file, then assume the |
| time if not yet correct, and don't check the |
| key timestamps. As soon as the current time is |
| later then the timestamp, update the timestamp |
| and start checking keys */ |
| if (daemon->timestamp_file) |
| { |
| if (daemon->back_to_the_future == 0 && difftime(timestamp_time, curtime) <= 0) |
| { |
| if (utimes(daemon->timestamp_file, NULL) != 0) |
| my_syslog(LOG_ERR, _("failed to update mtime on %s: %s"), daemon->timestamp_file, strerror(errno)); |
| |
| my_syslog(LOG_INFO, _("system time considered valid, now checking DNSSEC signature timestamps.")); |
| daemon->back_to_the_future = 1; |
| daemon->dnssec_no_time_check = 0; |
| queue_event(EVENT_RELOAD); /* purge cache */ |
| } |
| |
| if (daemon->back_to_the_future == 0) |
| return 1; |
| } |
| else if (daemon->dnssec_no_time_check) |
| return 1; |
| |
| /* We must explicitly check against wanted values, because of SERIAL_UNDEF */ |
| return serial_compare_32(curtime, date_start) == SERIAL_GT |
| && serial_compare_32(curtime, date_end) == SERIAL_LT; |
| } |
| |
| /* Return bytes of canonicalised rdata, when the return value is zero, the remaining |
| data, pointed to by *p, should be used raw. */ |
| static int get_rdata(struct dns_header *header, size_t plen, unsigned char *end, char *buff, int bufflen, |
| unsigned char **p, u16 **desc) |
| { |
| int d = **desc; |
| |
| /* No more data needs mangling */ |
| if (d == (u16)-1) |
| { |
| /* If there's more data than we have space for, just return what fits, |
| we'll get called again for more chunks */ |
| if (end - *p > bufflen) |
| { |
| memcpy(buff, *p, bufflen); |
| *p += bufflen; |
| return bufflen; |
| } |
| |
| return 0; |
| } |
| |
| (*desc)++; |
| |
| if (d == 0 && extract_name(header, plen, p, buff, 1, 0)) |
| /* domain-name, canonicalise */ |
| return to_wire(buff); |
| else |
| { |
| /* plain data preceding a domain-name, don't run off the end of the data */ |
| if ((end - *p) < d) |
| d = end - *p; |
| |
| if (d != 0) |
| { |
| memcpy(buff, *p, d); |
| *p += d; |
| } |
| |
| return d; |
| } |
| } |
| |
| /* Bubble sort the RRset into the canonical order. |
| Note that the byte-streams from two RRs may get unsynced: consider |
| RRs which have two domain-names at the start and then other data. |
| The domain-names may have different lengths in each RR, but sort equal |
| |
| ------------ |
| |abcde|fghi| |
| ------------ |
| |abcd|efghi| |
| ------------ |
| |
| leaving the following bytes as deciding the order. Hence the nasty left1 and left2 variables. |
| */ |
| |
| static int sort_rrset(struct dns_header *header, size_t plen, u16 *rr_desc, int rrsetidx, |
| unsigned char **rrset, char *buff1, char *buff2) |
| { |
| int swap, quit, i, j; |
| |
| do |
| { |
| for (swap = 0, i = 0; i < rrsetidx-1; i++) |
| { |
| int rdlen1, rdlen2, left1, left2, len1, len2, len, rc; |
| u16 *dp1, *dp2; |
| unsigned char *end1, *end2; |
| /* Note that these have been determined to be OK previously, |
| so we don't need to check for NULL return here. */ |
| unsigned char *p1 = skip_name(rrset[i], header, plen, 10); |
| unsigned char *p2 = skip_name(rrset[i+1], header, plen, 10); |
| |
| p1 += 8; /* skip class, type, ttl */ |
| GETSHORT(rdlen1, p1); |
| end1 = p1 + rdlen1; |
| |
| p2 += 8; /* skip class, type, ttl */ |
| GETSHORT(rdlen2, p2); |
| end2 = p2 + rdlen2; |
| |
| dp1 = dp2 = rr_desc; |
| |
| for (quit = 0, left1 = 0, left2 = 0, len1 = 0, len2 = 0; !quit;) |
| { |
| if (left1 != 0) |
| memmove(buff1, buff1 + len1 - left1, left1); |
| |
| if ((len1 = get_rdata(header, plen, end1, buff1 + left1, (MAXDNAME * 2) - left1, &p1, &dp1)) == 0) |
| { |
| quit = 1; |
| len1 = end1 - p1; |
| memcpy(buff1 + left1, p1, len1); |
| } |
| len1 += left1; |
| |
| if (left2 != 0) |
| memmove(buff2, buff2 + len2 - left2, left2); |
| |
| if ((len2 = get_rdata(header, plen, end2, buff2 + left2, (MAXDNAME *2) - left2, &p2, &dp2)) == 0) |
| { |
| quit = 1; |
| len2 = end2 - p2; |
| memcpy(buff2 + left2, p2, len2); |
| } |
| len2 += left2; |
| |
| if (len1 > len2) |
| left1 = len1 - len2, left2 = 0, len = len2; |
| else |
| left2 = len2 - len1, left1 = 0, len = len1; |
| |
| rc = (len == 0) ? 0 : memcmp(buff1, buff2, len); |
| |
| if (rc > 0 || (rc == 0 && quit && len1 > len2)) |
| { |
| unsigned char *tmp = rrset[i+1]; |
| rrset[i+1] = rrset[i]; |
| rrset[i] = tmp; |
| swap = quit = 1; |
| } |
| else if (rc == 0 && quit && len1 == len2) |
| { |
| /* Two RRs are equal, remove one copy. RFC 4034, para 6.3 */ |
| for (j = i+1; j < rrsetidx-1; j++) |
| rrset[j] = rrset[j+1]; |
| rrsetidx--; |
| i--; |
| } |
| else if (rc < 0) |
| quit = 1; |
| } |
| } |
| } while (swap); |
| |
| return rrsetidx; |
| } |
| |
| static unsigned char **rrset = NULL, **sigs = NULL; |
| |
| /* Get pointers to RRset members and signature(s) for same. |
| Check signatures, and return keyname associated in keyname. */ |
| static int explore_rrset(struct dns_header *header, size_t plen, int class, int type, |
| char *name, char *keyname, int *sigcnt, int *rrcnt) |
| { |
| static int rrset_sz = 0, sig_sz = 0; |
| unsigned char *p; |
| int rrsetidx, sigidx, j, rdlen, res; |
| int gotkey = 0; |
| |
| if (!(p = skip_questions(header, plen))) |
| return STAT_BOGUS; |
| |
| /* look for RRSIGs for this RRset and get pointers to each RR in the set. */ |
| for (rrsetidx = 0, sigidx = 0, j = ntohs(header->ancount) + ntohs(header->nscount); |
| j != 0; j--) |
| { |
| unsigned char *pstart, *pdata; |
| int stype, sclass, type_covered; |
| |
| pstart = p; |
| |
| if (!(res = extract_name(header, plen, &p, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(stype, p); |
| GETSHORT(sclass, p); |
| p += 4; /* TTL */ |
| |
| pdata = p; |
| |
| GETSHORT(rdlen, p); |
| |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return 0; |
| |
| if (res == 1 && sclass == class) |
| { |
| if (stype == type) |
| { |
| if (!expand_workspace(&rrset, &rrset_sz, rrsetidx)) |
| return 0; |
| |
| rrset[rrsetidx++] = pstart; |
| } |
| |
| if (stype == T_RRSIG) |
| { |
| if (rdlen < 18) |
| return 0; /* bad packet */ |
| |
| GETSHORT(type_covered, p); |
| p += 16; /* algo, labels, orig_ttl, sig_expiration, sig_inception, key_tag */ |
| |
| if (gotkey) |
| { |
| /* If there's more than one SIG, ensure they all have same keyname */ |
| if (extract_name(header, plen, &p, keyname, 0, 0) != 1) |
| return 0; |
| } |
| else |
| { |
| gotkey = 1; |
| |
| if (!extract_name(header, plen, &p, keyname, 1, 0)) |
| return 0; |
| |
| /* RFC 4035 5.3.1 says that the Signer's Name field MUST equal |
| the name of the zone containing the RRset. We can't tell that |
| for certain, but we can check that the RRset name is equal to |
| or encloses the signers name, which should be enough to stop |
| an attacker using signatures made with the key of an unrelated |
| zone he controls. Note that the root key is always allowed. */ |
| if (*keyname != 0) |
| { |
| char *name_start; |
| for (name_start = name; !hostname_isequal(name_start, keyname); ) |
| if ((name_start = strchr(name_start, '.'))) |
| name_start++; /* chop a label off and try again */ |
| else |
| return 0; |
| } |
| } |
| |
| |
| if (type_covered == type) |
| { |
| if (!expand_workspace(&sigs, &sig_sz, sigidx)) |
| return 0; |
| |
| sigs[sigidx++] = pdata; |
| } |
| |
| p = pdata + 2; /* restore for ADD_RDLEN */ |
| } |
| } |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return 0; |
| } |
| |
| *sigcnt = sigidx; |
| *rrcnt = rrsetidx; |
| |
| return 1; |
| } |
| |
| /* Validate a single RRset (class, type, name) in the supplied DNS reply |
| Return code: |
| STAT_SECURE if it validates. |
| STAT_SECURE_WILDCARD if it validates and is the result of wildcard expansion. |
| (In this case *wildcard_out points to the "body" of the wildcard within name.) |
| STAT_BOGUS signature is wrong, bad packet. |
| STAT_NEED_KEY need DNSKEY to complete validation (name is returned in keyname) |
| STAT_NEED_DS need DS to complete validation (name is returned in keyname) |
| |
| If key is non-NULL, use that key, which has the algo and tag given in the params of those names, |
| otherwise find the key in the cache. |
| |
| Name is unchanged on exit. keyname is used as workspace and trashed. |
| |
| Call explore_rrset first to find and count RRs and sigs. |
| */ |
| static int validate_rrset(time_t now, struct dns_header *header, size_t plen, int class, int type, int sigidx, int rrsetidx, |
| char *name, char *keyname, char **wildcard_out, struct blockdata *key, int keylen, int algo_in, int keytag_in) |
| { |
| unsigned char *p; |
| int rdlen, j, name_labels, algo, labels, orig_ttl, key_tag; |
| struct crec *crecp = NULL; |
| u16 *rr_desc = rrfilter_desc(type); |
| u32 sig_expiration, sig_inception |
| ; |
| if (wildcard_out) |
| *wildcard_out = NULL; |
| |
| name_labels = count_labels(name); /* For 4035 5.3.2 check */ |
| |
| /* Sort RRset records into canonical order. |
| Note that at this point keyname and daemon->workspacename buffs are |
| unused, and used as workspace by the sort. */ |
| rrsetidx = sort_rrset(header, plen, rr_desc, rrsetidx, rrset, daemon->workspacename, keyname); |
| |
| /* Now try all the sigs to try and find one which validates */ |
| for (j = 0; j <sigidx; j++) |
| { |
| unsigned char *psav, *sig, *digest; |
| int i, wire_len, sig_len; |
| const struct nettle_hash *hash; |
| void *ctx; |
| char *name_start; |
| u32 nsigttl; |
| |
| p = sigs[j]; |
| GETSHORT(rdlen, p); /* rdlen >= 18 checked previously */ |
| psav = p; |
| |
| p += 2; /* type_covered - already checked */ |
| algo = *p++; |
| labels = *p++; |
| GETLONG(orig_ttl, p); |
| GETLONG(sig_expiration, p); |
| GETLONG(sig_inception, p); |
| GETSHORT(key_tag, p); |
| |
| if (!extract_name(header, plen, &p, keyname, 1, 0)) |
| return STAT_BOGUS; |
| |
| if (!check_date_range(sig_inception, sig_expiration) || |
| labels > name_labels || |
| !(hash = hash_find(algo_digest_name(algo))) || |
| !hash_init(hash, &ctx, &digest)) |
| continue; |
| |
| /* OK, we have the signature record, see if the relevant DNSKEY is in the cache. */ |
| if (!key && !(crecp = cache_find_by_name(NULL, keyname, now, F_DNSKEY))) |
| return STAT_NEED_KEY; |
| |
| sig = p; |
| sig_len = rdlen - (p - psav); |
| |
| nsigttl = htonl(orig_ttl); |
| |
| hash->update(ctx, 18, psav); |
| wire_len = to_wire(keyname); |
| hash->update(ctx, (unsigned int)wire_len, (unsigned char*)keyname); |
| from_wire(keyname); |
| |
| for (i = 0; i < rrsetidx; ++i) |
| { |
| int seg; |
| unsigned char *end, *cp; |
| u16 len, *dp; |
| |
| p = rrset[i]; |
| |
| if (!extract_name(header, plen, &p, name, 1, 10)) |
| return STAT_BOGUS; |
| |
| name_start = name; |
| |
| /* if more labels than in RRsig name, hash *.<no labels in rrsig labels field> 4035 5.3.2 */ |
| if (labels < name_labels) |
| { |
| int k; |
| for (k = name_labels - labels; k != 0; k--) |
| { |
| while (*name_start != '.' && *name_start != 0) |
| name_start++; |
| if (k != 1 && *name_start == '.') |
| name_start++; |
| } |
| |
| if (wildcard_out) |
| *wildcard_out = name_start+1; |
| |
| name_start--; |
| *name_start = '*'; |
| } |
| |
| wire_len = to_wire(name_start); |
| hash->update(ctx, (unsigned int)wire_len, (unsigned char *)name_start); |
| hash->update(ctx, 4, p); /* class and type */ |
| hash->update(ctx, 4, (unsigned char *)&nsigttl); |
| |
| p += 8; /* skip class, type, ttl */ |
| GETSHORT(rdlen, p); |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; |
| |
| end = p + rdlen; |
| |
| /* canonicalise rdata and calculate length of same, use name buffer as workspace. |
| Note that name buffer is twice MAXDNAME long in DNSSEC mode. */ |
| cp = p; |
| dp = rr_desc; |
| for (len = 0; (seg = get_rdata(header, plen, end, name, MAXDNAME * 2, &cp, &dp)) != 0; len += seg); |
| len += end - cp; |
| len = htons(len); |
| hash->update(ctx, 2, (unsigned char *)&len); |
| |
| /* Now canonicalise again and digest. */ |
| cp = p; |
| dp = rr_desc; |
| while ((seg = get_rdata(header, plen, end, name, MAXDNAME * 2, &cp, &dp))) |
| hash->update(ctx, seg, (unsigned char *)name); |
| if (cp != end) |
| hash->update(ctx, end - cp, cp); |
| } |
| |
| hash->digest(ctx, hash->digest_size, digest); |
| |
| /* namebuff used for workspace above, restore to leave unchanged on exit */ |
| p = (unsigned char*)(rrset[0]); |
| extract_name(header, plen, &p, name, 1, 0); |
| |
| if (key) |
| { |
| if (algo_in == algo && keytag_in == key_tag && |
| verify(key, keylen, sig, sig_len, digest, hash->digest_size, algo)) |
| return STAT_SECURE; |
| } |
| else |
| { |
| /* iterate through all possible keys 4035 5.3.1 */ |
| for (; crecp; crecp = cache_find_by_name(crecp, keyname, now, F_DNSKEY)) |
| if (crecp->addr.key.algo == algo && |
| crecp->addr.key.keytag == key_tag && |
| crecp->uid == (unsigned int)class && |
| verify(crecp->addr.key.keydata, crecp->addr.key.keylen, sig, sig_len, digest, hash->digest_size, algo)) |
| return (labels < name_labels) ? STAT_SECURE_WILDCARD : STAT_SECURE; |
| } |
| } |
| |
| return STAT_BOGUS; |
| } |
| |
| |
| /* The DNS packet is expected to contain the answer to a DNSKEY query. |
| Put all DNSKEYs in the answer which are valid into the cache. |
| return codes: |
| STAT_OK Done, key(s) in cache. |
| STAT_BOGUS No DNSKEYs found, which can be validated with DS, |
| or self-sign for DNSKEY RRset is not valid, bad packet. |
| STAT_NEED_DS DS records to validate a key not found, name in keyname |
| STAT_NEED_KEY DNSKEY records to validate a key not found, name in keyname |
| */ |
| int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, int class) |
| { |
| unsigned char *psave, *p = (unsigned char *)(header+1); |
| struct crec *crecp, *recp1; |
| int rc, j, qtype, qclass, ttl, rdlen, flags, algo, valid, keytag; |
| struct blockdata *key; |
| struct all_addr a; |
| |
| if (ntohs(header->qdcount) != 1 || |
| !extract_name(header, plen, &p, name, 1, 4)) |
| return STAT_BOGUS; |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| |
| if (qtype != T_DNSKEY || qclass != class || ntohs(header->ancount) == 0) |
| return STAT_BOGUS; |
| |
| /* See if we have cached a DS record which validates this key */ |
| if (!(crecp = cache_find_by_name(NULL, name, now, F_DS))) |
| { |
| strcpy(keyname, name); |
| return STAT_NEED_DS; |
| } |
| |
| /* NOTE, we need to find ONE DNSKEY which matches the DS */ |
| for (valid = 0, j = ntohs(header->ancount); j != 0 && !valid; j--) |
| { |
| /* Ensure we have type, class TTL and length */ |
| if (!(rc = extract_name(header, plen, &p, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| GETLONG(ttl, p); |
| GETSHORT(rdlen, p); |
| |
| if (!CHECK_LEN(header, p, plen, rdlen) || rdlen < 4) |
| return STAT_BOGUS; /* bad packet */ |
| |
| if (qclass != class || qtype != T_DNSKEY || rc == 2) |
| { |
| p += rdlen; |
| continue; |
| } |
| |
| psave = p; |
| |
| GETSHORT(flags, p); |
| if (*p++ != 3) |
| return STAT_BOGUS; |
| algo = *p++; |
| keytag = dnskey_keytag(algo, flags, p, rdlen - 4); |
| key = NULL; |
| |
| /* key must have zone key flag set */ |
| if (flags & 0x100) |
| key = blockdata_alloc((char*)p, rdlen - 4); |
| |
| p = psave; |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| { |
| if (key) |
| blockdata_free(key); |
| return STAT_BOGUS; /* bad packet */ |
| } |
| |
| /* No zone key flag or malloc failure */ |
| if (!key) |
| continue; |
| |
| for (recp1 = crecp; recp1; recp1 = cache_find_by_name(recp1, name, now, F_DS)) |
| { |
| void *ctx; |
| unsigned char *digest, *ds_digest; |
| const struct nettle_hash *hash; |
| int sigcnt, rrcnt; |
| |
| if (recp1->addr.ds.algo == algo && |
| recp1->addr.ds.keytag == keytag && |
| recp1->uid == (unsigned int)class && |
| (hash = hash_find(ds_digest_name(recp1->addr.ds.digest))) && |
| hash_init(hash, &ctx, &digest)) |
| |
| { |
| int wire_len = to_wire(name); |
| |
| /* Note that digest may be different between DSs, so |
| we can't move this outside the loop. */ |
| hash->update(ctx, (unsigned int)wire_len, (unsigned char *)name); |
| hash->update(ctx, (unsigned int)rdlen, psave); |
| hash->digest(ctx, hash->digest_size, digest); |
| |
| from_wire(name); |
| |
| if (!(recp1->flags & F_NEG) && |
| recp1->addr.ds.keylen == (int)hash->digest_size && |
| (ds_digest = blockdata_retrieve(recp1->addr.key.keydata, recp1->addr.ds.keylen, NULL)) && |
| memcmp(ds_digest, digest, recp1->addr.ds.keylen) == 0 && |
| explore_rrset(header, plen, class, T_DNSKEY, name, keyname, &sigcnt, &rrcnt) && |
| sigcnt != 0 && rrcnt != 0 && |
| validate_rrset(now, header, plen, class, T_DNSKEY, sigcnt, rrcnt, name, keyname, |
| NULL, key, rdlen - 4, algo, keytag) == STAT_SECURE) |
| { |
| valid = 1; |
| break; |
| } |
| } |
| } |
| blockdata_free(key); |
| } |
| |
| if (valid) |
| { |
| /* DNSKEY RRset determined to be OK, now cache it. */ |
| cache_start_insert(); |
| |
| p = skip_questions(header, plen); |
| |
| for (j = ntohs(header->ancount); j != 0; j--) |
| { |
| /* Ensure we have type, class TTL and length */ |
| if (!(rc = extract_name(header, plen, &p, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| GETLONG(ttl, p); |
| GETSHORT(rdlen, p); |
| |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; /* bad packet */ |
| |
| if (qclass == class && rc == 1) |
| { |
| psave = p; |
| |
| if (qtype == T_DNSKEY) |
| { |
| if (rdlen < 4) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(flags, p); |
| if (*p++ != 3) |
| return STAT_BOGUS; |
| algo = *p++; |
| keytag = dnskey_keytag(algo, flags, p, rdlen - 4); |
| |
| /* Cache needs to known class for DNSSEC stuff */ |
| a.addr.dnssec.class = class; |
| |
| if ((key = blockdata_alloc((char*)p, rdlen - 4))) |
| { |
| if (!(recp1 = cache_insert(name, &a, now, ttl, F_FORWARD | F_DNSKEY | F_DNSSECOK))) |
| { |
| blockdata_free(key); |
| return STAT_BOGUS; |
| } |
| else |
| { |
| a.addr.log.keytag = keytag; |
| a.addr.log.algo = algo; |
| if (algo_digest_name(algo)) |
| log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DNSKEY keytag %hu, algo %hu"); |
| else |
| log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DNSKEY keytag %hu, algo %hu (not supported)"); |
| |
| recp1->addr.key.keylen = rdlen - 4; |
| recp1->addr.key.keydata = key; |
| recp1->addr.key.algo = algo; |
| recp1->addr.key.keytag = keytag; |
| recp1->addr.key.flags = flags; |
| } |
| } |
| } |
| |
| p = psave; |
| } |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; /* bad packet */ |
| } |
| |
| /* commit cache insert. */ |
| cache_end_insert(); |
| return STAT_OK; |
| } |
| |
| log_query(F_NOEXTRA | F_UPSTREAM, name, NULL, "BOGUS DNSKEY"); |
| return STAT_BOGUS; |
| } |
| |
| /* The DNS packet is expected to contain the answer to a DS query |
| Put all DSs in the answer which are valid into the cache. |
| Also handles replies which prove that there's no DS at this location, |
| either because the zone is unsigned or this isn't a zone cut. These are |
| cached too. |
| return codes: |
| STAT_OK At least one valid DS found and in cache. |
| STAT_BOGUS no DS in reply or not signed, fails validation, bad packet. |
| STAT_NEED_KEY DNSKEY records to validate a DS not found, name in keyname |
| STAT_NEED_DS DS record needed. |
| */ |
| |
| int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, int class) |
| { |
| unsigned char *p = (unsigned char *)(header+1); |
| int qtype, qclass, rc, i, neganswer, nons; |
| int aclass, atype, rdlen; |
| unsigned long ttl; |
| struct all_addr a; |
| |
| if (ntohs(header->qdcount) != 1 || |
| !(p = skip_name(p, header, plen, 4))) |
| return STAT_BOGUS; |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| |
| if (qtype != T_DS || qclass != class) |
| rc = STAT_BOGUS; |
| else |
| rc = dnssec_validate_reply(now, header, plen, name, keyname, NULL, 0, &neganswer, &nons); |
| |
| if (rc == STAT_INSECURE) |
| rc = STAT_BOGUS; |
| |
| p = (unsigned char *)(header+1); |
| extract_name(header, plen, &p, name, 1, 4); |
| p += 4; /* qtype, qclass */ |
| |
| /* If the key needed to validate the DS is on the same domain as the DS, we'll |
| loop getting nowhere. Stop that now. This can happen of the DS answer comes |
| from the DS's zone, and not the parent zone. */ |
| if (rc == STAT_BOGUS || (rc == STAT_NEED_KEY && hostname_isequal(name, keyname))) |
| { |
| log_query(F_NOEXTRA | F_UPSTREAM, name, NULL, "BOGUS DS"); |
| return STAT_BOGUS; |
| } |
| |
| if (rc != STAT_SECURE) |
| return rc; |
| |
| if (!neganswer) |
| { |
| cache_start_insert(); |
| |
| for (i = 0; i < ntohs(header->ancount); i++) |
| { |
| if (!(rc = extract_name(header, plen, &p, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(atype, p); |
| GETSHORT(aclass, p); |
| GETLONG(ttl, p); |
| GETSHORT(rdlen, p); |
| |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; /* bad packet */ |
| |
| if (aclass == class && atype == T_DS && rc == 1) |
| { |
| int algo, digest, keytag; |
| unsigned char *psave = p; |
| struct blockdata *key; |
| struct crec *crecp; |
| |
| if (rdlen < 4) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(keytag, p); |
| algo = *p++; |
| digest = *p++; |
| |
| /* Cache needs to known class for DNSSEC stuff */ |
| a.addr.dnssec.class = class; |
| |
| if ((key = blockdata_alloc((char*)p, rdlen - 4))) |
| { |
| if (!(crecp = cache_insert(name, &a, now, ttl, F_FORWARD | F_DS | F_DNSSECOK))) |
| { |
| blockdata_free(key); |
| return STAT_BOGUS; |
| } |
| else |
| { |
| a.addr.log.keytag = keytag; |
| a.addr.log.algo = algo; |
| a.addr.log.digest = digest; |
| if (ds_digest_name(digest) && algo_digest_name(algo)) |
| log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DS keytag %hu, algo %hu, digest %hu"); |
| else |
| log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DS keytag %hu, algo %hu, digest %hu (not supported)"); |
| |
| crecp->addr.ds.digest = digest; |
| crecp->addr.ds.keydata = key; |
| crecp->addr.ds.algo = algo; |
| crecp->addr.ds.keytag = keytag; |
| crecp->addr.ds.keylen = rdlen - 4; |
| } |
| } |
| |
| p = psave; |
| } |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; /* bad packet */ |
| } |
| |
| cache_end_insert(); |
| |
| } |
| else |
| { |
| int flags = F_FORWARD | F_DS | F_NEG | F_DNSSECOK; |
| unsigned long minttl = ULONG_MAX; |
| |
| if (!(p = skip_section(p, ntohs(header->ancount), header, plen))) |
| return STAT_BOGUS; |
| |
| if (RCODE(header) == NXDOMAIN) |
| flags |= F_NXDOMAIN; |
| |
| /* We only cache validated DS records, DNSSECOK flag hijacked |
| to store presence/absence of NS. */ |
| if (nons) |
| flags &= ~F_DNSSECOK; |
| |
| for (i = ntohs(header->nscount); i != 0; i--) |
| { |
| if (!(p = skip_name(p, header, plen, 0))) |
| return STAT_BOGUS; |
| |
| GETSHORT(atype, p); |
| GETSHORT(aclass, p); |
| GETLONG(ttl, p); |
| GETSHORT(rdlen, p); |
| |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; /* bad packet */ |
| |
| if (aclass != class || atype != T_SOA) |
| { |
| p += rdlen; |
| continue; |
| } |
| |
| if (ttl < minttl) |
| minttl = ttl; |
| |
| /* MNAME */ |
| if (!(p = skip_name(p, header, plen, 0))) |
| return STAT_BOGUS; |
| /* RNAME */ |
| if (!(p = skip_name(p, header, plen, 20))) |
| return STAT_BOGUS; |
| p += 16; /* SERIAL REFRESH RETRY EXPIRE */ |
| |
| GETLONG(ttl, p); /* minTTL */ |
| if (ttl < minttl) |
| minttl = ttl; |
| |
| break; |
| } |
| |
| if (i != 0) |
| { |
| cache_start_insert(); |
| |
| a.addr.dnssec.class = class; |
| if (!cache_insert(name, &a, now, ttl, flags)) |
| return STAT_BOGUS; |
| |
| cache_end_insert(); |
| |
| log_query(F_NOEXTRA | F_UPSTREAM, name, NULL, "no DS"); |
| } |
| } |
| |
| return STAT_OK; |
| } |
| |
| |
| /* 4034 6.1 */ |
| static int hostname_cmp(const char *a, const char *b) |
| { |
| char *sa, *ea, *ca, *sb, *eb, *cb; |
| unsigned char ac, bc; |
| |
| sa = ea = (char *)a + strlen(a); |
| sb = eb = (char *)b + strlen(b); |
| |
| while (1) |
| { |
| while (sa != a && *(sa-1) != '.') |
| sa--; |
| |
| while (sb != b && *(sb-1) != '.') |
| sb--; |
| |
| ca = sa; |
| cb = sb; |
| |
| while (1) |
| { |
| if (ca == ea) |
| { |
| if (cb == eb) |
| break; |
| |
| return -1; |
| } |
| |
| if (cb == eb) |
| return 1; |
| |
| ac = (unsigned char) *ca++; |
| bc = (unsigned char) *cb++; |
| |
| if (ac >= 'A' && ac <= 'Z') |
| ac += 'a' - 'A'; |
| if (bc >= 'A' && bc <= 'Z') |
| bc += 'a' - 'A'; |
| |
| if (ac < bc) |
| return -1; |
| else if (ac != bc) |
| return 1; |
| } |
| |
| |
| if (sa == a) |
| { |
| if (sb == b) |
| return 0; |
| |
| return -1; |
| } |
| |
| if (sb == b) |
| return 1; |
| |
| ea = --sa; |
| eb = --sb; |
| } |
| } |
| |
| static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsigned char **nsecs, int nsec_count, |
| char *workspace1, char *workspace2, char *name, int type, int *nons) |
| { |
| int i, rc, rdlen; |
| unsigned char *p, *psave; |
| int offset = (type & 0xff) >> 3; |
| int mask = 0x80 >> (type & 0x07); |
| |
| if (nons) |
| *nons = 1; |
| |
| /* Find NSEC record that proves name doesn't exist */ |
| for (i = 0; i < nsec_count; i++) |
| { |
| p = nsecs[i]; |
| if (!extract_name(header, plen, &p, workspace1, 1, 10)) |
| return 0; |
| p += 8; /* class, type, TTL */ |
| GETSHORT(rdlen, p); |
| psave = p; |
| if (!extract_name(header, plen, &p, workspace2, 1, 10)) |
| return 0; |
| |
| rc = hostname_cmp(workspace1, name); |
| |
| if (rc == 0) |
| { |
| /* 4035 para 5.4. Last sentence */ |
| if (type == T_NSEC || type == T_RRSIG) |
| return 1; |
| |
| /* NSEC with the same name as the RR we're testing, check |
| that the type in question doesn't appear in the type map */ |
| rdlen -= p - psave; |
| /* rdlen is now length of type map, and p points to it */ |
| |
| /* If we can prove that there's no NS record, return that information. */ |
| if (nons && rdlen >= 2 && p[0] == 0 && (p[2] & (0x80 >> T_NS)) != 0) |
| *nons = 0; |
| |
| if (rdlen >= 2 && p[0] == 0) |
| { |
| /* A CNAME answer would also be valid, so if there's a CNAME is should |
| have been returned. */ |
| if ((p[2] & (0x80 >> T_CNAME)) != 0) |
| return 0; |
| |
| /* If the SOA bit is set for a DS record, then we have the |
| DS from the wrong side of the delegation. */ |
| if (type == T_DS && (p[2] & (0x80 >> T_SOA)) != 0) |
| return 0; |
| } |
| |
| while (rdlen >= 2) |
| { |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return 0; |
| |
| if (p[0] == type >> 8) |
| { |
| /* Does the NSEC say our type exists? */ |
| if (offset < p[1] && (p[offset+2] & mask) != 0) |
| return 0; |
| |
| break; /* finished checking */ |
| } |
| |
| rdlen -= p[1]; |
| p += p[1]; |
| } |
| |
| return 1; |
| } |
| else if (rc == -1) |
| { |
| /* Normal case, name falls between NSEC name and next domain name, |
| wrap around case, name falls between NSEC name (rc == -1) and end */ |
| if (hostname_cmp(workspace2, name) >= 0 || hostname_cmp(workspace1, workspace2) >= 0) |
| return 1; |
| } |
| else |
| { |
| /* wrap around case, name falls between start and next domain name */ |
| if (hostname_cmp(workspace1, workspace2) >= 0 && hostname_cmp(workspace2, name) >=0 ) |
| return 1; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* return digest length, or zero on error */ |
| static int hash_name(char *in, unsigned char **out, struct nettle_hash const *hash, |
| unsigned char *salt, int salt_len, int iterations) |
| { |
| void *ctx; |
| unsigned char *digest; |
| int i; |
| |
| if (!hash_init(hash, &ctx, &digest)) |
| return 0; |
| |
| hash->update(ctx, to_wire(in), (unsigned char *)in); |
| hash->update(ctx, salt_len, salt); |
| hash->digest(ctx, hash->digest_size, digest); |
| |
| for(i = 0; i < iterations; i++) |
| { |
| hash->update(ctx, hash->digest_size, digest); |
| hash->update(ctx, salt_len, salt); |
| hash->digest(ctx, hash->digest_size, digest); |
| } |
| |
| from_wire(in); |
| |
| *out = digest; |
| return hash->digest_size; |
| } |
| |
| /* Decode base32 to first "." or end of string */ |
| static int base32_decode(char *in, unsigned char *out) |
| { |
| int oc, on, c, mask, i; |
| unsigned char *p = out; |
| |
| for (c = *in, oc = 0, on = 0; c != 0 && c != '.'; c = *++in) |
| { |
| if (c >= '0' && c <= '9') |
| c -= '0'; |
| else if (c >= 'a' && c <= 'v') |
| c -= 'a', c += 10; |
| else if (c >= 'A' && c <= 'V') |
| c -= 'A', c += 10; |
| else |
| return 0; |
| |
| for (mask = 0x10, i = 0; i < 5; i++) |
| { |
| if (c & mask) |
| oc |= 1; |
| mask = mask >> 1; |
| if (((++on) & 7) == 0) |
| *p++ = oc; |
| oc = oc << 1; |
| } |
| } |
| |
| if ((on & 7) != 0) |
| return 0; |
| |
| return p - out; |
| } |
| |
| static int check_nsec3_coverage(struct dns_header *header, size_t plen, int digest_len, unsigned char *digest, int type, |
| char *workspace1, char *workspace2, unsigned char **nsecs, int nsec_count, int *nons) |
| { |
| int i, hash_len, salt_len, base32_len, rdlen, flags; |
| unsigned char *p, *psave; |
| |
| for (i = 0; i < nsec_count; i++) |
| if ((p = nsecs[i])) |
| { |
| if (!extract_name(header, plen, &p, workspace1, 1, 0) || |
| !(base32_len = base32_decode(workspace1, (unsigned char *)workspace2))) |
| return 0; |
| |
| p += 8; /* class, type, TTL */ |
| GETSHORT(rdlen, p); |
| psave = p; |
| p++; /* algo */ |
| flags = *p++; /* flags */ |
| p += 2; /* iterations */ |
| salt_len = *p++; /* salt_len */ |
| p += salt_len; /* salt */ |
| hash_len = *p++; /* p now points to next hashed name */ |
| |
| if (!CHECK_LEN(header, p, plen, hash_len)) |
| return 0; |
| |
| if (digest_len == base32_len && hash_len == base32_len) |
| { |
| int rc = memcmp(workspace2, digest, digest_len); |
| |
| if (rc == 0) |
| { |
| /* We found an NSEC3 whose hashed name exactly matches the query, so |
| we just need to check the type map. p points to the RR data for the record. */ |
| |
| int offset = (type & 0xff) >> 3; |
| int mask = 0x80 >> (type & 0x07); |
| |
| p += hash_len; /* skip next-domain hash */ |
| rdlen -= p - psave; |
| |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return 0; |
| |
| if (rdlen >= 2 && p[0] == 0) |
| { |
| /* If we can prove that there's no NS record, return that information. */ |
| if (nons && (p[2] & (0x80 >> T_NS)) != 0) |
| *nons = 0; |
| |
| /* A CNAME answer would also be valid, so if there's a CNAME is should |
| have been returned. */ |
| if ((p[2] & (0x80 >> T_CNAME)) != 0) |
| return 0; |
| |
| /* If the SOA bit is set for a DS record, then we have the |
| DS from the wrong side of the delegation. */ |
| if (type == T_DS && (p[2] & (0x80 >> T_SOA)) != 0) |
| return 0; |
| } |
| |
| while (rdlen >= 2) |
| { |
| if (p[0] == type >> 8) |
| { |
| /* Does the NSEC3 say our type exists? */ |
| if (offset < p[1] && (p[offset+2] & mask) != 0) |
| return 0; |
| |
| break; /* finished checking */ |
| } |
| |
| rdlen -= p[1]; |
| p += p[1]; |
| } |
| |
| return 1; |
| } |
| else if (rc < 0) |
| { |
| /* Normal case, hash falls between NSEC3 name-hash and next domain name-hash, |
| wrap around case, name-hash falls between NSEC3 name-hash and end */ |
| if (memcmp(p, digest, digest_len) >= 0 || memcmp(workspace2, p, digest_len) >= 0) |
| { |
| if ((flags & 0x01) && nons) /* opt out */ |
| *nons = 0; |
| |
| return 1; |
| } |
| } |
| else |
| { |
| /* wrap around case, name falls between start and next domain name */ |
| if (memcmp(workspace2, p, digest_len) >= 0 && memcmp(p, digest, digest_len) >= 0) |
| { |
| if ((flags & 0x01) && nons) /* opt out */ |
| *nons = 0; |
| |
| return 1; |
| } |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| static int prove_non_existence_nsec3(struct dns_header *header, size_t plen, unsigned char **nsecs, int nsec_count, |
| char *workspace1, char *workspace2, char *name, int type, char *wildname, int *nons) |
| { |
| unsigned char *salt, *p, *digest; |
| int digest_len, i, iterations, salt_len, base32_len, algo = 0; |
| struct nettle_hash const *hash; |
| char *closest_encloser, *next_closest, *wildcard; |
| |
| if (nons) |
| *nons = 1; |
| |
| /* Look though the NSEC3 records to find the first one with |
| an algorithm we support. |
| |
| Take the algo, iterations, and salt of that record |
| as the ones we're going to use, and prune any |
| that don't match. */ |
| |
| for (i = 0; i < nsec_count; i++) |
| { |
| if (!(p = skip_name(nsecs[i], header, plen, 15))) |
| return 0; /* bad packet */ |
| |
| p += 10; /* type, class, TTL, rdlen */ |
| algo = *p++; |
| |
| if ((hash = hash_find(nsec3_digest_name(algo)))) |
| break; /* known algo */ |
| } |
| |
| /* No usable NSEC3s */ |
| if (i == nsec_count) |
| return 0; |
| |
| p++; /* flags */ |
| |
| GETSHORT (iterations, p); |
| /* Upper-bound iterations, to avoid DoS. |
| Strictly, there are lower bounds for small keys, but |
| since we don't have key size info here, at least limit |
| to the largest bound, for 4096-bit keys. RFC 5155 10.3 */ |
| if (iterations > 2500) |
| return 0; |
| |
| salt_len = *p++; |
| salt = p; |
| if (!CHECK_LEN(header, salt, plen, salt_len)) |
| return 0; /* bad packet */ |
| |
| /* Now prune so we only have NSEC3 records with same iterations, salt and algo */ |
| for (i = 0; i < nsec_count; i++) |
| { |
| unsigned char *nsec3p = nsecs[i]; |
| int this_iter, flags; |
| |
| nsecs[i] = NULL; /* Speculative, will be restored if OK. */ |
| |
| if (!(p = skip_name(nsec3p, header, plen, 15))) |
| return 0; /* bad packet */ |
| |
| p += 10; /* type, class, TTL, rdlen */ |
| |
| if (*p++ != algo) |
| continue; |
| |
| flags = *p++; /* flags */ |
| |
| /* 5155 8.2 */ |
| if (flags != 0 && flags != 1) |
| continue; |
| |
| GETSHORT(this_iter, p); |
| if (this_iter != iterations) |
| continue; |
| |
| if (salt_len != *p++) |
| continue; |
| |
| if (!CHECK_LEN(header, p, plen, salt_len)) |
| return 0; /* bad packet */ |
| |
| if (memcmp(p, salt, salt_len) != 0) |
| continue; |
| |
| /* All match, put the pointer back */ |
| nsecs[i] = nsec3p; |
| } |
| |
| if ((digest_len = hash_name(name, &digest, hash, salt, salt_len, iterations)) == 0) |
| return 0; |
| |
| if (check_nsec3_coverage(header, plen, digest_len, digest, type, workspace1, workspace2, nsecs, nsec_count, nons)) |
| return 1; |
| |
| /* Can't find an NSEC3 which covers the name directly, we need the "closest encloser NSEC3" |
| or an answer inferred from a wildcard record. */ |
| closest_encloser = name; |
| next_closest = NULL; |
| |
| do |
| { |
| if (*closest_encloser == '.') |
| closest_encloser++; |
| |
| if (wildname && hostname_isequal(closest_encloser, wildname)) |
| break; |
| |
| if ((digest_len = hash_name(closest_encloser, &digest, hash, salt, salt_len, iterations)) == 0) |
| return 0; |
| |
| for (i = 0; i < nsec_count; i++) |
| if ((p = nsecs[i])) |
| { |
| if (!extract_name(header, plen, &p, workspace1, 1, 0) || |
| !(base32_len = base32_decode(workspace1, (unsigned char *)workspace2))) |
| return 0; |
| |
| if (digest_len == base32_len && |
| memcmp(digest, workspace2, digest_len) == 0) |
| break; /* Gotit */ |
| } |
| |
| if (i != nsec_count) |
| break; |
| |
| next_closest = closest_encloser; |
| } |
| while ((closest_encloser = strchr(closest_encloser, '.'))); |
| |
| if (!closest_encloser || !next_closest) |
| return 0; |
| |
| /* Look for NSEC3 that proves the non-existence of the next-closest encloser */ |
| if ((digest_len = hash_name(next_closest, &digest, hash, salt, salt_len, iterations)) == 0) |
| return 0; |
| |
| if (!check_nsec3_coverage(header, plen, digest_len, digest, type, workspace1, workspace2, nsecs, nsec_count, NULL)) |
| return 0; |
| |
| /* Finally, check that there's no seat of wildcard synthesis */ |
| if (!wildname) |
| { |
| if (!(wildcard = strchr(next_closest, '.')) || wildcard == next_closest) |
| return 0; |
| |
| wildcard--; |
| *wildcard = '*'; |
| |
| if ((digest_len = hash_name(wildcard, &digest, hash, salt, salt_len, iterations)) == 0) |
| return 0; |
| |
| if (!check_nsec3_coverage(header, plen, digest_len, digest, type, workspace1, workspace2, nsecs, nsec_count, NULL)) |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int prove_non_existence(struct dns_header *header, size_t plen, char *keyname, char *name, int qtype, int qclass, char *wildname, int *nons) |
| { |
| static unsigned char **nsecset = NULL; |
| static int nsecset_sz = 0; |
| |
| int type_found = 0; |
| unsigned char *p = skip_questions(header, plen); |
| int type, class, rdlen, i, nsecs_found; |
| |
| /* Move to NS section */ |
| if (!p || !(p = skip_section(p, ntohs(header->ancount), header, plen))) |
| return 0; |
| |
| for (nsecs_found = 0, i = ntohs(header->nscount); i != 0; i--) |
| { |
| unsigned char *pstart = p; |
| |
| if (!(p = skip_name(p, header, plen, 10))) |
| return 0; |
| |
| GETSHORT(type, p); |
| GETSHORT(class, p); |
| p += 4; /* TTL */ |
| GETSHORT(rdlen, p); |
| |
| if (class == qclass && (type == T_NSEC || type == T_NSEC3)) |
| { |
| /* No mixed NSECing 'round here, thankyouverymuch */ |
| if (type_found != 0 && type_found != type) |
| return 0; |
| |
| type_found = type; |
| |
| if (!expand_workspace(&nsecset, &nsecset_sz, nsecs_found)) |
| return 0; |
| |
| nsecset[nsecs_found++] = pstart; |
| } |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return 0; |
| } |
| |
| if (type_found == T_NSEC) |
| return prove_non_existence_nsec(header, plen, nsecset, nsecs_found, daemon->workspacename, keyname, name, qtype, nons); |
| else if (type_found == T_NSEC3) |
| return prove_non_existence_nsec3(header, plen, nsecset, nsecs_found, daemon->workspacename, keyname, name, qtype, wildname, nons); |
| else |
| return 0; |
| } |
| |
| /* Check signing status of name. |
| returns: |
| STAT_SECURE zone is signed. |
| STAT_INSECURE zone proved unsigned. |
| STAT_NEED_DS require DS record of name returned in keyname. |
| STAT_NEED_KEY require DNSKEY record of name returned in keyname. |
| name returned unaltered. |
| */ |
| static int zone_status(char *name, int class, char *keyname, time_t now) |
| { |
| int name_start = strlen(name); /* for when TA is root */ |
| struct crec *crecp; |
| char *p; |
| |
| /* First, work towards the root, looking for a trust anchor. |
| This can either be one configured, or one previously cached. |
| We can assume, if we don't find one first, that there is |
| a trust anchor at the root. */ |
| for (p = name; p; p = strchr(p, '.')) |
| { |
| if (*p == '.') |
| p++; |
| |
| if (cache_find_by_name(NULL, p, now, F_DS)) |
| { |
| name_start = p - name; |
| break; |
| } |
| } |
| |
| /* Now work away from the trust anchor */ |
| while (1) |
| { |
| strcpy(keyname, &name[name_start]); |
| |
| if (!(crecp = cache_find_by_name(NULL, keyname, now, F_DS))) |
| return STAT_NEED_DS; |
| |
| /* F_DNSSECOK misused in DS cache records to non-existence of NS record. |
| F_NEG && !F_DNSSECOK implies that we've proved there's no DS record here, |
| but that's because there's no NS record either, ie this isn't the start |
| of a zone. We only prove that the DNS tree below a node is unsigned when |
| we prove that we're at a zone cut AND there's no DS record. */ |
| if (crecp->flags & F_NEG) |
| { |
| if (crecp->flags & F_DNSSECOK) |
| return STAT_INSECURE; /* proved no DS here */ |
| } |
| else |
| { |
| /* If all the DS records have digest and/or sig algos we don't support, |
| then the zone is insecure. Note that if an algo |
| appears in the DS, then RRSIGs for that algo MUST |
| exist for each RRset: 4035 para 2.2 So if we find |
| a DS here with digest and sig we can do, we're entitled |
| to assume we can validate the zone and if we can't later, |
| because an RRSIG is missing we return BOGUS. |
| */ |
| do |
| { |
| if (crecp->uid == (unsigned int)class && |
| ds_digest_name(crecp->addr.ds.digest) && |
| algo_digest_name(crecp->addr.ds.algo)) |
| break; |
| } |
| while ((crecp = cache_find_by_name(crecp, keyname, now, F_DS))); |
| |
| if (!crecp) |
| return STAT_INSECURE; |
| } |
| |
| if (name_start == 0) |
| break; |
| |
| for (p = &name[name_start-2]; (*p != '.') && (p != name); p--); |
| |
| if (p != name) |
| p++; |
| |
| name_start = p - name; |
| } |
| |
| return STAT_SECURE; |
| } |
| |
| /* Validate all the RRsets in the answer and authority sections of the reply (4035:3.2.3) |
| Return code: |
| STAT_SECURE if it validates. |
| STAT_INSECURE at least one RRset not validated, because in unsigned zone. |
| STAT_BOGUS signature is wrong, bad packet, no validation where there should be. |
| STAT_NEED_KEY need DNSKEY to complete validation (name is returned in keyname, class in *class) |
| STAT_NEED_DS need DS to complete validation (name is returned in keyname) |
| |
| daemon->rr_status points to a char array which corressponds to the RRs in the |
| answer section (only). This is set to 1 for each RR which is validated, and 0 for any which aren't. |
| */ |
| int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, |
| int *class, int check_unsigned, int *neganswer, int *nons) |
| { |
| static unsigned char **targets = NULL; |
| static int target_sz = 0; |
| |
| unsigned char *ans_start, *p1, *p2; |
| int type1, class1, rdlen1 = 0, type2, class2, rdlen2, qclass, qtype, targetidx; |
| int i, j, rc; |
| int secure = STAT_SECURE; |
| |
| /* extend rr_status if necessary */ |
| if (daemon->rr_status_sz < ntohs(header->ancount)) |
| { |
| char *new = whine_malloc(ntohs(header->ancount) + 64); |
| |
| if (!new) |
| return STAT_BOGUS; |
| |
| free(daemon->rr_status); |
| daemon->rr_status = new; |
| daemon->rr_status_sz = ntohs(header->ancount) + 64; |
| } |
| |
| memset(daemon->rr_status, 0, ntohs(header->ancount)); |
| |
| if (neganswer) |
| *neganswer = 0; |
| |
| if (RCODE(header) == SERVFAIL || ntohs(header->qdcount) != 1) |
| return STAT_BOGUS; |
| |
| if (RCODE(header) != NXDOMAIN && RCODE(header) != NOERROR) |
| return STAT_INSECURE; |
| |
| p1 = (unsigned char *)(header+1); |
| |
| /* Find all the targets we're looking for answers to. |
| The zeroth array element is for the query, subsequent ones |
| for CNAME targets, unless the query is for a CNAME. */ |
| |
| if (!expand_workspace(&targets, &target_sz, 0)) |
| return STAT_BOGUS; |
| |
| targets[0] = p1; |
| targetidx = 1; |
| |
| if (!extract_name(header, plen, &p1, name, 1, 4)) |
| return STAT_BOGUS; |
| |
| GETSHORT(qtype, p1); |
| GETSHORT(qclass, p1); |
| ans_start = p1; |
| |
| /* Can't validate an RRSIG query */ |
| if (qtype == T_RRSIG) |
| return STAT_INSECURE; |
| |
| if (qtype != T_CNAME) |
| for (j = ntohs(header->ancount); j != 0; j--) |
| { |
| if (!(p1 = skip_name(p1, header, plen, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type2, p1); |
| p1 += 6; /* class, TTL */ |
| GETSHORT(rdlen2, p1); |
| |
| if (type2 == T_CNAME) |
| { |
| if (!expand_workspace(&targets, &target_sz, targetidx)) |
| return STAT_BOGUS; |
| |
| targets[targetidx++] = p1; /* pointer to target name */ |
| } |
| |
| if (!ADD_RDLEN(header, p1, plen, rdlen2)) |
| return STAT_BOGUS; |
| } |
| |
| for (p1 = ans_start, i = 0; i < ntohs(header->ancount) + ntohs(header->nscount); i++) |
| { |
| if (i != 0 && !ADD_RDLEN(header, p1, plen, rdlen1)) |
| return STAT_BOGUS; |
| |
| if (!extract_name(header, plen, &p1, name, 1, 10)) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type1, p1); |
| GETSHORT(class1, p1); |
| p1 += 4; /* TTL */ |
| GETSHORT(rdlen1, p1); |
| |
| /* Don't try and validate RRSIGs! */ |
| if (type1 == T_RRSIG) |
| continue; |
| |
| /* Check if we've done this RRset already */ |
| for (p2 = ans_start, j = 0; j < i; j++) |
| { |
| if (!(rc = extract_name(header, plen, &p2, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type2, p2); |
| GETSHORT(class2, p2); |
| p2 += 4; /* TTL */ |
| GETSHORT(rdlen2, p2); |
| |
| if (type2 == type1 && class2 == class1 && rc == 1) |
| break; /* Done it before: name, type, class all match. */ |
| |
| if (!ADD_RDLEN(header, p2, plen, rdlen2)) |
| return STAT_BOGUS; |
| } |
| |
| if (j != i) |
| { |
| /* Done already: copy the validation status */ |
| if (i < ntohs(header->ancount)) |
| daemon->rr_status[i] = daemon->rr_status[j]; |
| } |
| else |
| { |
| /* Not done, validate now */ |
| int sigcnt, rrcnt; |
| char *wildname; |
| |
| if (!explore_rrset(header, plen, class1, type1, name, keyname, &sigcnt, &rrcnt)) |
| return STAT_BOGUS; |
| |
| /* No signatures for RRset. We can be configured to assume this is OK and return a INSECURE result. */ |
| if (sigcnt == 0) |
| { |
| if (check_unsigned) |
| { |
| rc = zone_status(name, class1, keyname, now); |
| if (rc == STAT_SECURE) |
| rc = STAT_BOGUS; |
| if (class) |
| *class = class1; /* Class for NEED_DS or NEED_KEY */ |
| } |
| else |
| rc = STAT_INSECURE; |
| |
| if (rc != STAT_INSECURE) |
| return rc; |
| } |
| else |
| { |
| /* explore_rrset() gives us key name from sigs in keyname. |
| Can't overwrite name here. */ |
| strcpy(daemon->workspacename, keyname); |
| rc = zone_status(daemon->workspacename, class1, keyname, now); |
| |
| if (rc == STAT_BOGUS || rc == STAT_NEED_KEY || rc == STAT_NEED_DS) |
| { |
| /* Zone is insecure, don't need to validate RRset */ |
| if (class) |
| *class = class1; /* Class for NEED_DS or NEED_KEY */ |
| return rc; |
| } |
| |
| /* Zone is insecure, don't need to validate RRset */ |
| if (rc == STAT_SECURE) |
| { |
| rc = validate_rrset(now, header, plen, class1, type1, sigcnt, |
| rrcnt, name, keyname, &wildname, NULL, 0, 0, 0); |
| |
| if (rc == STAT_BOGUS || rc == STAT_NEED_KEY || rc == STAT_NEED_DS) |
| { |
| if (class) |
| *class = class1; /* Class for DS or DNSKEY */ |
| return rc; |
| } |
| |
| /* rc is now STAT_SECURE or STAT_SECURE_WILDCARD */ |
| |
| /* Note that RR is validated */ |
| if (i < ntohs(header->ancount)) |
| daemon->rr_status[i] = 1; |
| |
| /* Note if we've validated either the answer to the question |
| or the target of a CNAME. Any not noted will need NSEC or |
| to be in unsigned space. */ |
| for (j = 0; j <targetidx; j++) |
| if ((p2 = targets[j])) |
| { |
| int rc1; |
| if (!(rc1 = extract_name(header, plen, &p2, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| if (class1 == qclass && rc1 == 1 && (type1 == T_CNAME || type1 == qtype || qtype == T_ANY )) |
| targets[j] = NULL; |
| } |
| |
| /* An attacker replay a wildcard answer with a different |
| answer and overlay a genuine RR. To prove this |
| hasn't happened, the answer must prove that |
| the genuine record doesn't exist. Check that here. |
| Note that we may not yet have validated the NSEC/NSEC3 RRsets. |
| That's not a problem since if the RRsets later fail |
| we'll return BOGUS then. */ |
| if (rc == STAT_SECURE_WILDCARD && |
| !prove_non_existence(header, plen, keyname, name, type1, class1, wildname, NULL)) |
| return STAT_BOGUS; |
| |
| rc = STAT_SECURE; |
| } |
| } |
| } |
| |
| if (rc == STAT_INSECURE) |
| secure = STAT_INSECURE; |
| } |
| |
| /* OK, all the RRsets validate, now see if we have a missing answer or CNAME target. */ |
| for (j = 0; j <targetidx; j++) |
| if ((p2 = targets[j])) |
| { |
| if (neganswer) |
| *neganswer = 1; |
| |
| if (!extract_name(header, plen, &p2, name, 1, 10)) |
| return STAT_BOGUS; /* bad packet */ |
| |
| /* NXDOMAIN or NODATA reply, unanswered question is (name, qclass, qtype) */ |
| |
| /* For anything other than a DS record, this situation is OK if either |
| the answer is in an unsigned zone, or there's a NSEC records. */ |
| if (!prove_non_existence(header, plen, keyname, name, qtype, qclass, NULL, nons)) |
| { |
| /* Empty DS without NSECS */ |
| if (qtype == T_DS) |
| return STAT_BOGUS; |
| |
| if ((rc = zone_status(name, qclass, keyname, now)) != STAT_SECURE) |
| { |
| if (class) |
| *class = qclass; /* Class for NEED_DS or NEED_KEY */ |
| return rc; |
| } |
| |
| return STAT_BOGUS; /* signed zone, no NSECs */ |
| } |
| } |
| |
| return secure; |
| } |
| |
| |
| /* Compute keytag (checksum to quickly index a key). See RFC4034 */ |
| int dnskey_keytag(int alg, int flags, unsigned char *key, int keylen) |
| { |
| if (alg == 1) |
| { |
| /* Algorithm 1 (RSAMD5) has a different (older) keytag calculation algorithm. |
| See RFC4034, Appendix B.1 */ |
| return key[keylen-4] * 256 + key[keylen-3]; |
| } |
| else |
| { |
| unsigned long ac = flags + 0x300 + alg; |
| int i; |
| |
| for (i = 0; i < keylen; ++i) |
| ac += (i & 1) ? key[i] : key[i] << 8; |
| |
| ac += (ac >> 16) & 0xffff; |
| return ac & 0xffff; |
| } |
| } |
| |
| size_t dnssec_generate_query(struct dns_header *header, unsigned char *end, char *name, int class, |
| int type, union mysockaddr *addr, int edns_pktsz) |
| { |
| unsigned char *p; |
| char *types = querystr("dnssec-query", type); |
| size_t ret; |
| |
| if (addr->sa.sa_family == AF_INET) |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV4, name, (struct all_addr *)&addr->in.sin_addr, types); |
| #ifdef HAVE_IPV6 |
| else |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV6, name, (struct all_addr *)&addr->in6.sin6_addr, types); |
| #endif |
| |
| header->qdcount = htons(1); |
| header->ancount = htons(0); |
| header->nscount = htons(0); |
| header->arcount = htons(0); |
| |
| header->hb3 = HB3_RD; |
| SET_OPCODE(header, QUERY); |
| /* For debugging, set Checking Disabled, otherwise, have the upstream check too, |
| this allows it to select auth servers when one is returning bad data. */ |
| header->hb4 = option_bool(OPT_DNSSEC_DEBUG) ? HB4_CD : 0; |
| |
| /* ID filled in later */ |
| |
| p = (unsigned char *)(header+1); |
| |
| p = do_rfc1035_name(p, name, NULL); |
| *p++ = 0; |
| PUTSHORT(type, p); |
| PUTSHORT(class, p); |
| |
| ret = add_do_bit(header, p - (unsigned char *)header, end); |
| |
| if (find_pseudoheader(header, ret, NULL, &p, NULL, NULL)) |
| PUTSHORT(edns_pktsz, p); |
| |
| return ret; |
| } |
| |
| unsigned char* hash_questions(struct dns_header *header, size_t plen, char *name) |
| { |
| int q; |
| unsigned int len; |
| unsigned char *p = (unsigned char *)(header+1); |
| const struct nettle_hash *hash; |
| void *ctx; |
| unsigned char *digest; |
| |
| if (!(hash = hash_find("sha1")) || !hash_init(hash, &ctx, &digest)) |
| return NULL; |
| |
| for (q = ntohs(header->qdcount); q != 0; q--) |
| { |
| if (!extract_name(header, plen, &p, name, 1, 4)) |
| break; /* bad packet */ |
| |
| len = to_wire(name); |
| hash->update(ctx, len, (unsigned char *)name); |
| /* CRC the class and type as well */ |
| hash->update(ctx, 4, p); |
| |
| p += 4; |
| if (!CHECK_LEN(header, p, plen, 0)) |
| break; /* bad packet */ |
| } |
| |
| hash->digest(ctx, hash->digest_size, digest); |
| return digest; |
| } |
| |
| #endif /* HAVE_DNSSEC */ |