| /* dnssec.c is Copyright (c) 2012 Giovanni Bajo <rasky@develer.com> |
| and Copyright (c) 2012-2014 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 |
| |
| #include <nettle/rsa.h> |
| #include <nettle/dsa.h> |
| #ifndef NO_NETTLE_ECC |
| # include <nettle/ecdsa.h> |
| # include <nettle/ecc-curve.h> |
| #endif |
| #include <nettle/nettle-meta.h> |
| #include <nettle/bignum.h> |
| |
| /* Nettle-3.0 moved to a new API for DSA. We use a name that's defined in the new API |
| to detect Nettle-3, and invoke the backwards compatibility mode. */ |
| #ifdef dsa_params_init |
| #include <nettle/dsa-compat.h> |
| #endif |
| |
| |
| #define SERIAL_UNDEF -100 |
| #define SERIAL_EQ 0 |
| #define SERIAL_LT -1 |
| #define SERIAL_GT 1 |
| |
| /* http://www.iana.org/assignments/ds-rr-types/ds-rr-types.xhtml */ |
| static char *ds_digest_name(int digest) |
| { |
| switch (digest) |
| { |
| case 1: return "sha1"; |
| case 2: return "sha256"; |
| case 3: return "gosthash94"; |
| case 4: return "sha384"; |
| default: return NULL; |
| } |
| } |
| |
| /* http://www.iana.org/assignments/dns-sec-alg-numbers/dns-sec-alg-numbers.xhtml */ |
| static char *algo_digest_name(int algo) |
| { |
| switch (algo) |
| { |
| case 1: return "md5"; |
| case 3: return "sha1"; |
| case 5: return "sha1"; |
| case 6: return "sha1"; |
| case 7: return "sha1"; |
| case 8: return "sha256"; |
| case 10: return "sha512"; |
| case 12: return "gosthash94"; |
| case 13: return "sha256"; |
| case 14: return "sha384"; |
| default: return NULL; |
| } |
| } |
| |
| /* Find pointer to correct hash function in nettle library */ |
| static const struct nettle_hash *hash_find(char *name) |
| { |
| int i; |
| |
| if (!name) |
| return NULL; |
| |
| for (i = 0; nettle_hashes[i]; i++) |
| { |
| if (strcmp(nettle_hashes[i]->name, name) == 0) |
| return nettle_hashes[i]; |
| } |
| |
| return NULL; |
| } |
| |
| /* expand ctx and digest memory allocations if necessary and init hash function */ |
| static int hash_init(const struct nettle_hash *hash, void **ctxp, unsigned char **digestp) |
| { |
| static void *ctx = NULL; |
| static unsigned char *digest = NULL; |
| static unsigned int ctx_sz = 0; |
| static unsigned int digest_sz = 0; |
| |
| void *new; |
| |
| if (ctx_sz < hash->context_size) |
| { |
| if (!(new = whine_malloc(hash->context_size))) |
| return 0; |
| if (ctx) |
| free(ctx); |
| ctx = new; |
| ctx_sz = hash->context_size; |
| } |
| |
| if (digest_sz < hash->digest_size) |
| { |
| if (!(new = whine_malloc(hash->digest_size))) |
| return 0; |
| if (digest) |
| free(digest); |
| digest = new; |
| digest_sz = hash->digest_size; |
| } |
| |
| *ctxp = ctx; |
| *digestp = digest; |
| |
| hash->init(ctx); |
| |
| return 1; |
| } |
| |
| static int dnsmasq_rsa_verify(struct blockdata *key_data, unsigned int key_len, unsigned char *sig, size_t sig_len, |
| unsigned char *digest, int algo) |
| { |
| unsigned char *p; |
| size_t exp_len; |
| |
| static struct rsa_public_key *key = NULL; |
| static mpz_t sig_mpz; |
| |
| if (key == NULL) |
| { |
| if (!(key = whine_malloc(sizeof(struct rsa_public_key)))) |
| return 0; |
| |
| nettle_rsa_public_key_init(key); |
| mpz_init(sig_mpz); |
| } |
| |
| if ((key_len < 3) || !(p = blockdata_retrieve(key_data, key_len, NULL))) |
| return 0; |
| |
| key_len--; |
| if ((exp_len = *p++) == 0) |
| { |
| GETSHORT(exp_len, p); |
| key_len -= 2; |
| } |
| |
| if (exp_len >= key_len) |
| return 0; |
| |
| key->size = key_len - exp_len; |
| mpz_import(key->e, exp_len, 1, 1, 0, 0, p); |
| mpz_import(key->n, key->size, 1, 1, 0, 0, p + exp_len); |
| |
| mpz_import(sig_mpz, sig_len, 1, 1, 0, 0, sig); |
| |
| switch (algo) |
| { |
| case 1: |
| return nettle_rsa_md5_verify_digest(key, digest, sig_mpz); |
| case 5: case 7: |
| return nettle_rsa_sha1_verify_digest(key, digest, sig_mpz); |
| case 8: |
| return nettle_rsa_sha256_verify_digest(key, digest, sig_mpz); |
| case 10: |
| return nettle_rsa_sha512_verify_digest(key, digest, sig_mpz); |
| } |
| |
| return 0; |
| } |
| |
| static int dnsmasq_dsa_verify(struct blockdata *key_data, unsigned int key_len, unsigned char *sig, size_t sig_len, |
| unsigned char *digest, int algo) |
| { |
| unsigned char *p; |
| unsigned int t; |
| |
| static struct dsa_public_key *key = NULL; |
| static struct dsa_signature *sig_struct; |
| |
| if (key == NULL) |
| { |
| if (!(sig_struct = whine_malloc(sizeof(struct dsa_signature))) || |
| !(key = whine_malloc(sizeof(struct dsa_public_key)))) |
| return 0; |
| |
| nettle_dsa_public_key_init(key); |
| nettle_dsa_signature_init(sig_struct); |
| } |
| |
| if ((sig_len < 41) || !(p = blockdata_retrieve(key_data, key_len, NULL))) |
| return 0; |
| |
| t = *p++; |
| |
| if (key_len < (213 + (t * 24))) |
| return 0; |
| |
| mpz_import(key->q, 20, 1, 1, 0, 0, p); p += 20; |
| mpz_import(key->p, 64 + (t*8), 1, 1, 0, 0, p); p += 64 + (t*8); |
| mpz_import(key->g, 64 + (t*8), 1, 1, 0, 0, p); p += 64 + (t*8); |
| mpz_import(key->y, 64 + (t*8), 1, 1, 0, 0, p); p += 64 + (t*8); |
| |
| mpz_import(sig_struct->r, 20, 1, 1, 0, 0, sig+1); |
| mpz_import(sig_struct->s, 20, 1, 1, 0, 0, sig+21); |
| |
| (void)algo; |
| |
| return nettle_dsa_sha1_verify_digest(key, digest, sig_struct); |
| } |
| |
| #ifndef NO_NETTLE_ECC |
| static int dnsmasq_ecdsa_verify(struct blockdata *key_data, unsigned int key_len, |
| unsigned char *sig, size_t sig_len, |
| unsigned char *digest, size_t digest_len, int algo) |
| { |
| unsigned char *p; |
| unsigned int t; |
| struct ecc_point *key; |
| |
| static struct ecc_point *key_256 = NULL, *key_384 = NULL; |
| static mpz_t x, y; |
| static struct dsa_signature *sig_struct; |
| |
| if (!sig_struct) |
| { |
| if (!(sig_struct = whine_malloc(sizeof(struct dsa_signature)))) |
| return 0; |
| |
| nettle_dsa_signature_init(sig_struct); |
| mpz_init(x); |
| mpz_init(y); |
| } |
| |
| switch (algo) |
| { |
| case 13: |
| if (!key_256) |
| { |
| if (!(key_256 = whine_malloc(sizeof(struct ecc_point)))) |
| return 0; |
| |
| nettle_ecc_point_init(key_256, &nettle_secp_256r1); |
| } |
| |
| key = key_256; |
| t = 32; |
| break; |
| |
| case 14: |
| if (!key_384) |
| { |
| if (!(key_384 = whine_malloc(sizeof(struct ecc_point)))) |
| return 0; |
| |
| nettle_ecc_point_init(key_384, &nettle_secp_384r1); |
| } |
| |
| key = key_384; |
| t = 48; |
| break; |
| |
| default: |
| return 0; |
| } |
| |
| if (sig_len != 2*t || key_len != 2*t || |
| (p = blockdata_retrieve(key_data, key_len, NULL))) |
| return 0; |
| |
| mpz_import(x, t , 1, 1, 0, 0, p); |
| mpz_import(y, t , 1, 1, 0, 0, p + t); |
| |
| if (!ecc_point_set(key, x, y)) |
| return 0; |
| |
| mpz_import(sig_struct->r, t, 1, 1, 0, 0, sig); |
| mpz_import(sig_struct->s, t, 1, 1, 0, 0, sig + t); |
| |
| return nettle_ecdsa_verify(key, digest_len, digest, sig_struct); |
| } |
| #endif |
| |
| static int verify(struct blockdata *key_data, unsigned int key_len, unsigned char *sig, size_t sig_len, |
| unsigned char *digest, size_t digest_len, int algo) |
| { |
| (void)digest_len; |
| |
| switch (algo) |
| { |
| case 1: case 5: case 7: case 8: case 10: |
| return dnsmasq_rsa_verify(key_data, key_len, sig, sig_len, digest, algo); |
| |
| case 3: case 6: |
| return dnsmasq_dsa_verify(key_data, key_len, sig, sig_len, digest, algo); |
| |
| #ifndef NO_NETTLE_ECC |
| case 13: case 14: |
| return dnsmasq_ecdsa_verify(key_data, key_len, sig, sig_len, digest, digest_len, algo); |
| #endif |
| } |
| |
| return 0; |
| } |
| |
| /* 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. |
| */ |
| static int to_wire(char *name) |
| { |
| unsigned char *l, *p, 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'; |
| |
| 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; |
| int len; |
| |
| for (l = (unsigned char *)name; *l != 0; l += len+1) |
| { |
| len = *l; |
| memmove(l, l+1, len); |
| 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(unsigned long s1, unsigned long 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; |
| } |
| |
| /* Check whether today/now is between date_start and date_end */ |
| static int check_date_range(unsigned long date_start, unsigned long date_end) |
| { |
| unsigned long curtime; |
| |
| /* Checking timestamps may be temporarily disabled */ |
| if (option_bool(OPT_DNSSEC_TIME)) |
| return 1; |
| |
| curtime = time(0); |
| |
| /* 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; |
| } |
| |
| static u16 *get_desc(int type) |
| { |
| /* List of RRtypes which include domains in the data. |
| 0 -> domain |
| integer -> no of plain bytes |
| -1 -> end |
| |
| zero is not a valid RRtype, so the final entry is returned for |
| anything which needs no mangling. |
| */ |
| |
| static u16 rr_desc[] = |
| { |
| T_NS, 0, -1, |
| T_MD, 0, -1, |
| T_MF, 0, -1, |
| T_CNAME, 0, -1, |
| T_SOA, 0, 0, -1, |
| T_MB, 0, -1, |
| T_MG, 0, -1, |
| T_MR, 0, -1, |
| T_PTR, 0, -1, |
| T_MINFO, 0, 0, -1, |
| T_MX, 2, 0, -1, |
| T_RP, 0, 0, -1, |
| T_AFSDB, 2, 0, -1, |
| T_RT, 2, 0, -1, |
| T_SIG, 18, 0, -1, |
| T_PX, 2, 0, 0, -1, |
| T_NXT, 0, -1, |
| T_KX, 2, 0, -1, |
| T_SRV, 6, 0, -1, |
| T_DNAME, 0, -1, |
| 0, -1 /* wildcard/catchall */ |
| }; |
| |
| u16 *p = rr_desc; |
| |
| while (*p != type && *p != 0) |
| while (*p++ != (u16)-1); |
| |
| return p+1; |
| } |
| |
| /* 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; |
| } |
| } |
| |
| static int expand_workspace(unsigned char ***wkspc, int *sz, int new) |
| { |
| unsigned char **p; |
| int new_sz = *sz; |
| |
| if (new_sz > new) |
| return 1; |
| |
| if (new >= 100) |
| return 0; |
| |
| new_sz += 5; |
| |
| if (!(p = whine_malloc((new_sz) * sizeof(unsigned char **)))) |
| return 0; |
| |
| if (*wkspc) |
| { |
| memcpy(p, *wkspc, *sz * sizeof(unsigned char **)); |
| free(*wkspc); |
| } |
| |
| *wkspc = p; |
| *sz = new_sz; |
| |
| return 1; |
| } |
| |
| /* 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 void 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; |
| |
| 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 - 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 - 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 = 1; |
| } |
| } |
| } while (swap); |
| } |
| |
| /* 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_NO_SIG no RRsigs found. |
| STAT_INSECURE RRset empty. |
| STAT_BOGUS signature is wrong, bad packet. |
| STAT_NEED_KEY need DNSKEY 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. |
| */ |
| static int validate_rrset(time_t now, struct dns_header *header, size_t plen, int class, int type, |
| char *name, char *keyname, char **wildcard_out, struct blockdata *key, int keylen, int algo_in, int keytag_in) |
| { |
| static unsigned char **rrset = NULL, **sigs = NULL; |
| static int rrset_sz = 0, sig_sz = 0; |
| |
| unsigned char *p; |
| int rrsetidx, sigidx, res, rdlen, j, name_labels; |
| struct crec *crecp = NULL; |
| int type_covered, algo, labels, orig_ttl, sig_expiration, sig_inception, key_tag; |
| u16 *rr_desc = get_desc(type); |
| |
| if (wildcard_out) |
| *wildcard_out = NULL; |
| |
| if (!(p = skip_questions(header, plen))) |
| return STAT_BOGUS; |
| |
| name_labels = count_labels(name); /* For 4035 5.3.2 check */ |
| |
| /* 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; |
| |
| 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 STAT_BOGUS; |
| |
| if (res == 1 && sclass == class) |
| { |
| if (stype == type) |
| { |
| if (!expand_workspace(&rrset, &rrset_sz, rrsetidx)) |
| return STAT_BOGUS; |
| |
| rrset[rrsetidx++] = pstart; |
| } |
| |
| if (stype == T_RRSIG) |
| { |
| if (rdlen < 18) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type_covered, p); |
| |
| if (type_covered == type) |
| { |
| if (!expand_workspace(&sigs, &sig_sz, sigidx)) |
| return STAT_BOGUS; |
| |
| sigs[sigidx++] = pdata; |
| } |
| |
| p = pdata + 2; /* restore for ADD_RDLEN */ |
| } |
| } |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; |
| } |
| |
| /* RRset empty */ |
| if (rrsetidx == 0) |
| return STAT_INSECURE; |
| |
| /* no RRSIGs */ |
| if (sigidx == 0) |
| return STAT_NO_SIG; |
| |
| /* 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. */ |
| 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; |
| |
| /* 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) |
| { |
| int failed = 0; |
| |
| 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 |
| { |
| failed = 1; |
| break; |
| } |
| |
| /* Bad sig, try another */ |
| if (failed) |
| continue; |
| } |
| |
| /* Other 5.3.1 checks */ |
| 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 */ |
| cp = p; |
| dp = rr_desc; |
| for (len = 0; (seg = get_rdata(header, plen, end, name, MAXDNAME, &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, &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_SECURE At least one valid DNSKEY found and 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 |
| */ |
| 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, type_covered; |
| 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; |
| } |
| |
| /* If we've cached that DS provably doesn't exist, result must be INSECURE */ |
| if (crecp->flags & F_NEG) |
| return STAT_INSECURE; |
| |
| /* 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; |
| |
| 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->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 && |
| validate_rrset(now, header, plen, class, T_DNSKEY, 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 and the RRsigs that sign 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_INSECURE; /* 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); |
| else |
| { |
| a.addr.keytag = keytag; |
| log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DNSKEY keytag %u"); |
| |
| 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; |
| } |
| } |
| } |
| else if (qtype == T_RRSIG) |
| { |
| /* RRSIG, cache if covers DNSKEY RRset */ |
| if (rdlen < 18) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type_covered, p); |
| |
| if (type_covered == T_DNSKEY) |
| { |
| a.addr.dnssec.class = class; |
| a.addr.dnssec.type = type_covered; |
| |
| algo = *p++; |
| p += 13; /* labels, orig_ttl, expiration, inception */ |
| GETSHORT(keytag, p); |
| if ((key = blockdata_alloc((char*)psave, rdlen))) |
| { |
| if (!(crecp = cache_insert(name, &a, now, ttl, F_FORWARD | F_DNSKEY | F_DS))) |
| blockdata_free(key); |
| else |
| { |
| crecp->addr.sig.keydata = key; |
| crecp->addr.sig.keylen = rdlen; |
| crecp->addr.sig.keytag = keytag; |
| crecp->addr.sig.type_covered = type_covered; |
| crecp->addr.sig.algo = algo; |
| } |
| } |
| } |
| } |
| |
| p = psave; |
| } |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; /* bad packet */ |
| } |
| |
| /* commit cache insert. */ |
| cache_end_insert(); |
| return STAT_SECURE; |
| } |
| |
| 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. |
| return codes: |
| STAT_SECURE At least one valid DS found and in cache. |
| STAT_NO_DS It's proved there's no DS here. |
| STAT_NO_NS It's proved there's no DS _or_ NS here. |
| STAT_BOGUS no DS in reply or not signed, fails validation, bad packet. |
| STAT_NEED_DNSKEY DNSKEY records to validate a DS not found, name in keyname |
| */ |
| |
| 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, val, i, neganswer, nons; |
| |
| 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) |
| val = STAT_BOGUS; |
| else |
| val = dnssec_validate_reply(now, header, plen, name, keyname, NULL, &neganswer, &nons); |
| /* Note dnssec_validate_reply() will have cached positive answers */ |
| |
| if (val == STAT_NO_SIG || val == STAT_INSECURE) |
| val = STAT_BOGUS; |
| |
| p = (unsigned char *)(header+1); |
| extract_name(header, plen, &p, name, 1, 4); |
| p += 4; /* qtype, qclass */ |
| |
| if (!(p = skip_section(p, ntohs(header->ancount), header, plen))) |
| val = STAT_BOGUS; |
| |
| if (val == STAT_BOGUS) |
| { |
| log_query(F_NOEXTRA | F_UPSTREAM, name, NULL, "BOGUS DS"); |
| return STAT_BOGUS; |
| } |
| |
| /* By here, the answer is proved secure, and a positive answer has been cached. */ |
| if (val == STAT_SECURE && neganswer) |
| { |
| int rdlen, flags = F_FORWARD | F_DS | F_NEG | F_DNSSECOK; |
| unsigned long ttl, minttl = ULONG_MAX; |
| struct all_addr a; |
| |
| 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(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 || qtype != 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; |
| cache_insert(name, &a, now, ttl, flags); |
| |
| cache_end_insert(); |
| |
| log_query(F_NOEXTRA | F_UPSTREAM, name, NULL, nons ? "no delegation" : "no DS"); |
| } |
| |
| return nons ? STAT_NO_NS : STAT_NO_DS; |
| } |
| |
| return val; |
| } |
| |
| /* 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--; |
| } |
| } |
| |
| /* Find all the NSEC or NSEC3 records in a reply. |
| return an array of pointers to them. */ |
| static int find_nsec_records(struct dns_header *header, size_t plen, unsigned char ***nsecsetp, int *nsecsetl, int class_reqd) |
| { |
| 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 == class_reqd && (type == T_NSEC || type == T_NSEC3)) |
| { |
| /* No mixed NSECing 'round here, thankyouverymuch */ |
| if (type_found == T_NSEC && type == T_NSEC3) |
| return 0; |
| if (type_found == T_NSEC3 && type == T_NSEC) |
| 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; |
| } |
| |
| *nsecsetp = nsecset; |
| *nsecsetl = nsecs_found; |
| |
| return type_found; |
| } |
| |
| 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 = 0; |
| |
| /* 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 STAT_BOGUS; |
| p += 8; /* class, type, TTL */ |
| GETSHORT(rdlen, p); |
| psave = p; |
| if (!extract_name(header, plen, &p, workspace2, 1, 10)) |
| return STAT_BOGUS; |
| |
| rc = hostname_cmp(workspace1, name); |
| |
| if (rc == 0) |
| { |
| /* 4035 para 5.4. Last sentence */ |
| if (type == T_NSEC || type == T_RRSIG) |
| return STAT_SECURE; |
| |
| /* 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 = 1; |
| |
| while (rdlen >= 2) |
| { |
| if (!CHECK_LEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; |
| |
| if (p[0] == type >> 8) |
| { |
| /* Does the NSEC say our type exists? */ |
| if (offset < p[1] && (p[offset+2] & mask) != 0) |
| return STAT_BOGUS; |
| |
| break; /* finshed checking */ |
| } |
| |
| rdlen -= p[1]; |
| p += p[1]; |
| } |
| |
| return STAT_SECURE; |
| } |
| 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) == 1 || hostname_cmp(workspace1, workspace2) == 1) |
| return STAT_SECURE; |
| } |
| else |
| { |
| /* wrap around case, name falls between start and next domain name */ |
| if (hostname_cmp(workspace1, workspace2) == 1 && hostname_cmp(workspace2, name) == 1) |
| return STAT_SECURE; |
| } |
| } |
| |
| return STAT_BOGUS; |
| } |
| |
| /* 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; |
| 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 += 4; /* algo, flags, 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 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 = 1; |
| |
| 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 STAT_BOGUS; |
| |
| break; /* finshed 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) |
| 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) |
| 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 = 0; |
| |
| /* Look though the NSEC3 records to find the first one with |
| an algorithm we support (currently only algo == 1). |
| |
| 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 STAT_BOGUS; /* bad packet */ |
| |
| p += 10; /* type, class, TTL, rdlen */ |
| algo = *p++; |
| |
| if (algo == 1) |
| break; /* known algo */ |
| } |
| |
| /* No usable NSEC3s */ |
| if (i == nsec_count) |
| return STAT_BOGUS; |
| |
| p++; /* flags */ |
| GETSHORT (iterations, p); |
| salt_len = *p++; |
| salt = p; |
| if (!CHECK_LEN(header, salt, plen, salt_len)) |
| return STAT_BOGUS; /* 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; |
| |
| nsecs[i] = NULL; /* Speculative, will be restored if OK. */ |
| |
| if (!(p = skip_name(nsec3p, header, plen, 15))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| p += 10; /* type, class, TTL, rdlen */ |
| |
| if (*p++ != algo) |
| continue; |
| |
| p++; /* flags */ |
| |
| GETSHORT(this_iter, p); |
| if (this_iter != iterations) |
| continue; |
| |
| if (salt_len != *p++) |
| continue; |
| |
| if (!CHECK_LEN(header, p, plen, salt_len)) |
| return STAT_BOGUS; /* bad packet */ |
| |
| if (memcmp(p, salt, salt_len) != 0) |
| continue; |
| |
| /* All match, put the pointer back */ |
| nsecs[i] = nsec3p; |
| } |
| |
| /* Algo is checked as 1 above */ |
| if (!(hash = hash_find("sha1"))) |
| return STAT_BOGUS; |
| |
| if ((digest_len = hash_name(name, &digest, hash, salt, salt_len, iterations)) == 0) |
| return STAT_BOGUS; |
| |
| if (check_nsec3_coverage(header, plen, digest_len, digest, type, workspace1, workspace2, nsecs, nsec_count, nons)) |
| return STAT_SECURE; |
| |
| /* 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 STAT_BOGUS; |
| |
| 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 STAT_BOGUS; |
| |
| 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) |
| return STAT_BOGUS; |
| |
| /* 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 STAT_BOGUS; |
| |
| if (!check_nsec3_coverage(header, plen, digest_len, digest, type, workspace1, workspace2, nsecs, nsec_count, NULL)) |
| return STAT_BOGUS; |
| |
| /* Finally, check that there's no seat of wildcard synthesis */ |
| if (!wildname) |
| { |
| if (!(wildcard = strchr(next_closest, '.')) || wildcard == next_closest) |
| return STAT_BOGUS; |
| |
| wildcard--; |
| *wildcard = '*'; |
| |
| if ((digest_len = hash_name(wildcard, &digest, hash, salt, salt_len, iterations)) == 0) |
| return STAT_BOGUS; |
| |
| if (!check_nsec3_coverage(header, plen, digest_len, digest, type, workspace1, workspace2, nsecs, nsec_count, NULL)) |
| return STAT_BOGUS; |
| } |
| |
| return STAT_SECURE; |
| } |
| |
| /* Validate all the RRsets in the answer and authority sections of the reply (4035:3.2.3) */ |
| /* Returns are the same as validate_rrset, plus the class if the missing key is in *class */ |
| int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, |
| int *class, int *neganswer, int *nons) |
| { |
| unsigned char *ans_start, *qname, *p1, *p2, **nsecs; |
| int type1, class1, rdlen1, type2, class2, rdlen2, qclass, qtype; |
| int i, j, rc, nsec_count, cname_count = CNAME_CHAIN; |
| int nsec_type = 0, have_answer = 0; |
| |
| 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; |
| |
| qname = p1 = (unsigned char *)(header+1); |
| |
| if (!extract_name(header, plen, &p1, name, 1, 4)) |
| return STAT_BOGUS; |
| |
| GETSHORT(qtype, p1); |
| GETSHORT(qclass, p1); |
| ans_start = p1; |
| |
| if (qtype == T_ANY) |
| have_answer = 1; |
| |
| /* Can't validate an RRISG query */ |
| if (qtype == T_RRSIG) |
| return STAT_INSECURE; |
| |
| cname_loop: |
| for (j = ntohs(header->ancount); j != 0; j--) |
| { |
| /* leave pointer to missing name in qname */ |
| |
| if (!(rc = extract_name(header, plen, &p1, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type2, p1); |
| GETSHORT(class2, p1); |
| p1 += 4; /* TTL */ |
| GETSHORT(rdlen2, p1); |
| |
| if (rc == 1 && qclass == class2) |
| { |
| /* Do we have an answer for the question? */ |
| if (type2 == qtype) |
| { |
| have_answer = 1; |
| break; |
| } |
| else if (type2 == T_CNAME) |
| { |
| qname = p1; |
| |
| /* looped CNAMES */ |
| if (!cname_count-- || !extract_name(header, plen, &p1, name, 1, 0)) |
| return STAT_BOGUS; |
| |
| p1 = ans_start; |
| goto cname_loop; |
| } |
| } |
| |
| if (!ADD_RDLEN(header, p1, plen, rdlen2)) |
| return STAT_BOGUS; |
| } |
| |
| if (neganswer && !have_answer) |
| *neganswer = 1; |
| |
| /* No data, therefore no sigs */ |
| if (ntohs(header->ancount) + ntohs(header->nscount) == 0) |
| return STAT_NO_SIG; |
| |
| for (p1 = ans_start, i = 0; i < ntohs(header->ancount) + ntohs(header->nscount); i++) |
| { |
| 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) |
| { |
| /* 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; |
| } |
| |
| /* Not done, validate now */ |
| if (j == i) |
| { |
| int ttl, keytag, algo, digest, type_covered; |
| unsigned char *psave; |
| struct all_addr a; |
| struct blockdata *key; |
| struct crec *crecp; |
| char *wildname; |
| int have_wildcard = 0; |
| |
| rc = validate_rrset(now, header, plen, class1, type1, name, keyname, &wildname, NULL, 0, 0, 0); |
| |
| if (rc == STAT_SECURE_WILDCARD) |
| { |
| have_wildcard = 1; |
| |
| /* 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 gennuine record doesn't exist. Check that here. */ |
| if (!nsec_type && !(nsec_type = find_nsec_records(header, plen, &nsecs, &nsec_count, class1))) |
| return STAT_BOGUS; /* No NSECs or bad packet */ |
| |
| if (nsec_type == T_NSEC) |
| rc = prove_non_existence_nsec(header, plen, nsecs, nsec_count, daemon->workspacename, keyname, name, type1, NULL); |
| else |
| rc = prove_non_existence_nsec3(header, plen, nsecs, nsec_count, daemon->workspacename, |
| keyname, name, type1, wildname, NULL); |
| |
| if (rc != STAT_SECURE) |
| return rc; |
| } |
| else if (rc != STAT_SECURE) |
| { |
| if (class) |
| *class = class1; /* Class for DS or DNSKEY */ |
| return rc; |
| } |
| |
| /* Cache RRsigs in answer section, and if we just validated a DS RRset, cache it */ |
| cache_start_insert(); |
| |
| for (p2 = ans_start, j = 0; j < ntohs(header->ancount); j++) |
| { |
| if (!(rc = extract_name(header, plen, &p2, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type2, p2); |
| GETSHORT(class2, p2); |
| GETLONG(ttl, p2); |
| GETSHORT(rdlen2, p2); |
| |
| if (!CHECK_LEN(header, p2, plen, rdlen2)) |
| return STAT_BOGUS; /* bad packet */ |
| |
| if (class2 == class1 && rc == 1) |
| { |
| psave = p2; |
| |
| if (type1 == T_DS && type2 == T_DS) |
| { |
| if (rdlen2 < 4) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(keytag, p2); |
| algo = *p2++; |
| digest = *p2++; |
| |
| /* Cache needs to known class for DNSSEC stuff */ |
| a.addr.dnssec.class = class2; |
| |
| if ((key = blockdata_alloc((char*)p2, rdlen2 - 4))) |
| { |
| if (!(crecp = cache_insert(name, &a, now, ttl, F_FORWARD | F_DS | F_DNSSECOK))) |
| blockdata_free(key); |
| else |
| { |
| a.addr.keytag = keytag; |
| log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DS keytag %u"); |
| crecp->addr.ds.digest = digest; |
| crecp->addr.ds.keydata = key; |
| crecp->addr.ds.algo = algo; |
| crecp->addr.ds.keytag = keytag; |
| crecp->addr.ds.keylen = rdlen2 - 4; |
| } |
| } |
| } |
| else if (type2 == T_RRSIG) |
| { |
| if (rdlen2 < 18) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type_covered, p2); |
| |
| if (type_covered == type1 && |
| (type_covered == T_A || type_covered == T_AAAA || |
| type_covered == T_CNAME || type_covered == T_DS || |
| type_covered == T_DNSKEY || type_covered == T_PTR)) |
| { |
| a.addr.dnssec.type = type_covered; |
| a.addr.dnssec.class = class1; |
| |
| algo = *p2++; |
| p2 += 13; /* labels, orig_ttl, expiration, inception */ |
| GETSHORT(keytag, p2); |
| |
| /* We don't cache sigs for wildcard answers, because to reproduce the |
| answer from the cache will require one or more NSEC/NSEC3 records |
| which we don't cache. The lack of the RRSIG ensures that a query for |
| this RRset asking for a secure answer will always be forwarded. */ |
| if (!have_wildcard && (key = blockdata_alloc((char*)psave, rdlen2))) |
| { |
| if (!(crecp = cache_insert(name, &a, now, ttl, F_FORWARD | F_DNSKEY | F_DS))) |
| blockdata_free(key); |
| else |
| { |
| crecp->addr.sig.keydata = key; |
| crecp->addr.sig.keylen = rdlen2; |
| crecp->addr.sig.keytag = keytag; |
| crecp->addr.sig.type_covered = type_covered; |
| crecp->addr.sig.algo = algo; |
| } |
| } |
| } |
| } |
| |
| p2 = psave; |
| } |
| |
| if (!ADD_RDLEN(header, p2, plen, rdlen2)) |
| return STAT_BOGUS; /* bad packet */ |
| } |
| |
| cache_end_insert(); |
| } |
| } |
| |
| if (!ADD_RDLEN(header, p1, plen, rdlen1)) |
| return STAT_BOGUS; |
| } |
| |
| /* OK, all the RRsets validate, now see if we have a NODATA or NXDOMAIN reply */ |
| if (have_answer) |
| return STAT_SECURE; |
| |
| /* NXDOMAIN or NODATA reply, prove that (name, class1, type1) can't exist */ |
| /* First marshall the NSEC records, if we've not done it previously */ |
| if (!nsec_type && !(nsec_type = find_nsec_records(header, plen, &nsecs, &nsec_count, qclass))) |
| return STAT_BOGUS; /* No NSECs */ |
| |
| /* Get name of missing answer */ |
| if (!extract_name(header, plen, &qname, name, 1, 0)) |
| return STAT_BOGUS; |
| |
| if (nsec_type == T_NSEC) |
| return prove_non_existence_nsec(header, plen, nsecs, nsec_count, daemon->workspacename, keyname, name, qtype, nons); |
| else |
| return prove_non_existence_nsec3(header, plen, nsecs, nsec_count, daemon->workspacename, keyname, name, qtype, NULL, nons); |
| } |
| |
| /* Chase the CNAME chain in the packet until the first record which _doesn't validate. |
| Needed for proving answer in unsigned space. |
| Return STAT_NEED_* |
| STAT_BOGUS - error |
| STAT_INSECURE - name of first non-secure record in name |
| */ |
| int dnssec_chase_cname(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname) |
| { |
| unsigned char *p = (unsigned char *)(header+1); |
| int type, class, qclass, rdlen, j, rc; |
| int cname_count = CNAME_CHAIN; |
| |
| /* Get question */ |
| if (!extract_name(header, plen, &p, name, 1, 4)) |
| return STAT_BOGUS; |
| |
| p +=2; /* type */ |
| GETSHORT(qclass, p); |
| |
| while (1) |
| { |
| for (j = ntohs(header->ancount); j != 0; j--) |
| { |
| if (!(rc = extract_name(header, plen, &p, name, 0, 10))) |
| return STAT_BOGUS; /* bad packet */ |
| |
| GETSHORT(type, p); |
| GETSHORT(class, p); |
| p += 4; /* TTL */ |
| GETSHORT(rdlen, p); |
| |
| /* Not target, loop */ |
| if (rc == 2 || qclass != class) |
| { |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return STAT_BOGUS; |
| continue; |
| } |
| |
| /* Got to end of CNAME chain. */ |
| if (type != T_CNAME) |
| return STAT_INSECURE; |
| |
| /* validate CNAME chain, return if insecure or need more data */ |
| rc = validate_rrset(now, header, plen, class, type, name, keyname, NULL, NULL, 0, 0, 0); |
| if (rc != STAT_SECURE) |
| { |
| if (rc == STAT_NO_SIG) |
| rc = STAT_INSECURE; |
| return rc; |
| } |
| |
| /* Loop down CNAME chain/ */ |
| if (!cname_count-- || |
| !extract_name(header, plen, &p, name, 1, 0) || |
| !(p = skip_questions(header, plen))) |
| return STAT_BOGUS; |
| |
| break; |
| } |
| |
| /* End of CNAME chain */ |
| return STAT_INSECURE; |
| } |
| } |
| |
| |
| /* 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, char *end, char *name, int class, int type, union mysockaddr *addr) |
| { |
| unsigned char *p; |
| char *types = querystr("dnssec-query", type); |
| |
| 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); |
| *p++ = 0; |
| PUTSHORT(type, p); |
| PUTSHORT(class, p); |
| |
| return add_do_bit(header, p - (unsigned char *)header, end); |
| } |
| |
| /* Go through a domain name, find "pointers" and fix them up based on how many bytes |
| we've chopped out of the packet, or check they don't point into an elided part. */ |
| static int check_name(unsigned char **namep, struct dns_header *header, size_t plen, int fixup, unsigned char **rrs, int rr_count) |
| { |
| unsigned char *ansp = *namep; |
| |
| while(1) |
| { |
| unsigned int label_type; |
| |
| if (!CHECK_LEN(header, ansp, plen, 1)) |
| return 0; |
| |
| label_type = (*ansp) & 0xc0; |
| |
| if (label_type == 0xc0) |
| { |
| /* pointer for compression. */ |
| unsigned int offset; |
| int i; |
| unsigned char *p; |
| |
| if (!CHECK_LEN(header, ansp, plen, 2)) |
| return 0; |
| |
| offset = ((*ansp++) & 0x3f) << 8; |
| offset |= *ansp++; |
| |
| p = offset + (unsigned char *)header; |
| |
| for (i = 0; i < rr_count; i++) |
| if (p < rrs[i]) |
| break; |
| else |
| if (i & 1) |
| offset -= rrs[i] - rrs[i-1]; |
| |
| /* does the pointer end up in an elided RR? */ |
| if (i & 1) |
| return 0; |
| |
| /* No, scale the pointer */ |
| if (fixup) |
| { |
| ansp -= 2; |
| *ansp++ = (offset >> 8) | 0xc0; |
| *ansp++ = offset & 0xff; |
| } |
| break; |
| } |
| else if (label_type == 0x80) |
| return 0; /* reserved */ |
| else if (label_type == 0x40) |
| { |
| /* Extended label type */ |
| unsigned int count; |
| |
| if (!CHECK_LEN(header, ansp, plen, 2)) |
| return 0; |
| |
| if (((*ansp++) & 0x3f) != 1) |
| return 0; /* we only understand bitstrings */ |
| |
| count = *(ansp++); /* Bits in bitstring */ |
| |
| if (count == 0) /* count == 0 means 256 bits */ |
| ansp += 32; |
| else |
| ansp += ((count-1)>>3)+1; |
| } |
| else |
| { /* label type == 0 Bottom six bits is length */ |
| unsigned int len = (*ansp++) & 0x3f; |
| |
| if (!ADD_RDLEN(header, ansp, plen, len)) |
| return 0; |
| |
| if (len == 0) |
| break; /* zero length label marks the end. */ |
| } |
| } |
| |
| *namep = ansp; |
| |
| return 1; |
| } |
| |
| /* Go through RRs and check or fixup the domain names contained within */ |
| static int check_rrs(unsigned char *p, struct dns_header *header, size_t plen, int fixup, unsigned char **rrs, int rr_count) |
| { |
| int i, type, class, rdlen; |
| unsigned char *pp; |
| |
| for (i = 0; i < ntohs(header->ancount) + ntohs(header->nscount) + ntohs(header->arcount); i++) |
| { |
| pp = p; |
| |
| if (!(p = skip_name(p, header, plen, 10))) |
| return 0; |
| |
| GETSHORT(type, p); |
| GETSHORT(class, p); |
| p += 4; /* TTL */ |
| GETSHORT(rdlen, p); |
| |
| if (type != T_NSEC && type != T_NSEC3 && type != T_RRSIG) |
| { |
| /* fixup name of RR */ |
| if (!check_name(&pp, header, plen, fixup, rrs, rr_count)) |
| return 0; |
| |
| if (class == C_IN) |
| { |
| u16 *d; |
| |
| for (pp = p, d = get_desc(type); *d != (u16)-1; d++) |
| { |
| if (*d != 0) |
| pp += *d; |
| else if (!check_name(&pp, header, plen, fixup, rrs, rr_count)) |
| return 0; |
| } |
| } |
| } |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| |
| size_t filter_rrsigs(struct dns_header *header, size_t plen) |
| { |
| static unsigned char **rrs; |
| static int rr_sz = 0; |
| |
| unsigned char *p = (unsigned char *)(header+1); |
| int i, rdlen, qtype, qclass, rr_found, chop_an, chop_ns, chop_ar; |
| |
| if (ntohs(header->qdcount) != 1 || |
| !(p = skip_name(p, header, plen, 4))) |
| return plen; |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| |
| /* First pass, find pointers to start and end of all the records we wish to elide: |
| records added for DNSSEC, unless explicity queried for */ |
| for (rr_found = 0, chop_ns = 0, chop_an = 0, chop_ar = 0, i = 0; |
| i < ntohs(header->ancount) + ntohs(header->nscount) + ntohs(header->arcount); |
| i++) |
| { |
| unsigned char *pstart = p; |
| int type, class; |
| |
| if (!(p = skip_name(p, header, plen, 10))) |
| return plen; |
| |
| GETSHORT(type, p); |
| GETSHORT(class, p); |
| p += 4; /* TTL */ |
| GETSHORT(rdlen, p); |
| |
| if ((type == T_NSEC || type == T_NSEC3 || type == T_RRSIG) && |
| (type != qtype || class != qclass)) |
| { |
| if (!expand_workspace(&rrs, &rr_sz, rr_found + 1)) |
| return plen; |
| |
| rrs[rr_found++] = pstart; |
| |
| if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return plen; |
| |
| rrs[rr_found++] = p; |
| |
| if (i < ntohs(header->ancount)) |
| chop_an++; |
| else if (i < (ntohs(header->nscount) + ntohs(header->ancount))) |
| chop_ns++; |
| else |
| chop_ar++; |
| } |
| else if (!ADD_RDLEN(header, p, plen, rdlen)) |
| return plen; |
| } |
| |
| /* Nothing to do. */ |
| if (rr_found == 0) |
| return plen; |
| |
| /* Second pass, look for pointers in names in the records we're keeping and make sure they don't |
| point to records we're going to elide. This is theoretically possible, but unlikely. If |
| it happens, we give up and leave the answer unchanged. */ |
| p = (unsigned char *)(header+1); |
| |
| /* question first */ |
| if (!check_name(&p, header, plen, 0, rrs, rr_found)) |
| return plen; |
| p += 4; /* qclass, qtype */ |
| |
| /* Now answers and NS */ |
| if (!check_rrs(p, header, plen, 0, rrs, rr_found)) |
| return plen; |
| |
| /* Third pass, elide records */ |
| for (p = rrs[0], i = 1; i < rr_found; i += 2) |
| { |
| unsigned char *start = rrs[i]; |
| unsigned char *end = (i != rr_found - 1) ? rrs[i+1] : ((unsigned char *)(header+1)) + plen; |
| |
| memmove(p, start, end-start); |
| p += end-start; |
| } |
| |
| plen = p - (unsigned char *)header; |
| header->ancount = htons(ntohs(header->ancount) - chop_an); |
| header->nscount = htons(ntohs(header->nscount) - chop_ns); |
| header->arcount = htons(ntohs(header->arcount) - chop_ar); |
| |
| /* Fourth pass, fix up pointers in the remaining records */ |
| p = (unsigned char *)(header+1); |
| |
| check_name(&p, header, plen, 1, rrs, rr_found); |
| p += 4; /* qclass, qtype */ |
| |
| check_rrs(p, header, plen, 1, rrs, rr_found); |
| |
| return plen; |
| } |
| |
| 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 */ |