struct all_addr *addrp = NULL;
unsigned int flags = 0;
struct server *start = NULL;
-#ifdef HAVE_DNSSEC
void *hash = hash_questions(header, plen, daemon->namebuff);
+#ifdef HAVE_DNSSEC
int do_dnssec = 0;
-#else
- unsigned int crc = questions_crc(header, plen, daemon->namebuff);
- void *hash = &crc;
#endif
unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL);
(void)do_bit;
/* may be no servers available. */
- if (forward || (hash && (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash))))
+ if (forward || (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash)))
{
/* If we didn't get an answer advertising a maximal packet in EDNS,
fall back to 1280, which should work everywhere on IPv6.
size_t nn;
struct server *server;
void *hash;
-#ifndef HAVE_DNSSEC
- unsigned int crc;
-#endif
/* packet buffer overwritten */
daemon->srv_save = NULL;
if (difftime(now, server->pktsz_reduced) > UDP_TEST_TIME)
server->edns_pktsz = daemon->edns_pktsz;
-#ifdef HAVE_DNSSEC
hash = hash_questions(header, n, daemon->namebuff);
-#else
- hash = &crc;
- crc = questions_crc(header, n, daemon->namebuff);
-#endif
+
if (!(forward = lookup_frec(ntohs(header->id), fd, family, hash)))
return;
nn = dnssec_generate_query(header,((unsigned char *) header) + server->edns_pktsz,
daemon->keyname, forward->class, T_DS, &server->addr, server->edns_pktsz);
}
- if ((hash = hash_questions(header, nn, daemon->namebuff)))
- memcpy(new->hash, hash, HASH_SIZE);
+ memcpy(new->hash, hash_questions(header, nn, daemon->namebuff), HASH_SIZE);
new->new_id = get_id();
header->id = htons(new->new_id);
/* Save query for retransmission */
if (!flags && last_server)
{
struct server *firstsendto = NULL;
-#ifdef HAVE_DNSSEC
- unsigned char *newhash, hash[HASH_SIZE];
- if ((newhash = hash_questions(header, (unsigned int)size, daemon->namebuff)))
- memcpy(hash, newhash, HASH_SIZE);
- else
- memset(hash, 0, HASH_SIZE);
-#else
- unsigned int crc = questions_crc(header, (unsigned int)size, daemon->namebuff);
-#endif
+ unsigned char hash[HASH_SIZE];
+ memcpy(hash, hash_questions(header, (unsigned int)size, daemon->namebuff), HASH_SIZE);
+
/* Loop round available servers until we succeed in connecting to one.
Note that this code subtly ensures that consecutive queries on this connection
which can go to the same server, do so. */
/* If the crc of the question section doesn't match the crc we sent, then
someone might be attempting to insert bogus values into the cache by
sending replies containing questions and bogus answers. */
-#ifdef HAVE_DNSSEC
- newhash = hash_questions(header, (unsigned int)m, daemon->namebuff);
- if (!newhash || memcmp(hash, newhash, HASH_SIZE) != 0)
+ if (memcmp(hash, hash_questions(header, (unsigned int)m, daemon->namebuff), HASH_SIZE) != 0)
+
{
m = 0;
break;
}
-#else
- if (crc != questions_crc(header, (unsigned int)m, daemon->namebuff))
- {
- m = 0;
- break;
- }
-#endif
m = process_reply(header, now, last_server, (unsigned int)m,
option_bool(OPT_NO_REBIND) && !norebind, no_cache_dnssec, cache_secure, bogusanswer,
for(f = daemon->frec_list; f; f = f->next)
if (f->sentto && f->new_id == id &&
- (!hash || memcmp(hash, f->hash, HASH_SIZE) == 0))
+ (memcmp(hash, f->hash, HASH_SIZE) == 0))
{
/* sent from random port */
if (family == AF_INET && f->rfd4 && f->rfd4->fd == fd)
--- /dev/null
+/* Copyright (c) 2012-2020 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/>.
+*/
+
+
+/* Hash the question section. This is used to safely detect query
+ retransmission and to detect answers to questions we didn't ask, which
+ might be poisoning attacks. Note that we decode the name rather
+ than CRC the raw bytes, since replies might be compressed differently.
+ We ignore case in the names for the same reason.
+
+ The hash used is SHA-256. If we're building with DNSSEC support,
+ we use the Nettle cypto library. If not, we prefer not to
+ add a dependency on Nettle, and use a stand-alone implementaion.
+*/
+
+#include "dnsmasq.h"
+
+#ifdef HAVE_DNSSEC
+unsigned char *hash_questions(struct dns_header *header, size_t plen, char *name)
+{
+ int q;
+ unsigned char *p = (unsigned char *)(header+1);
+ const struct nettle_hash *hash;
+ void *ctx;
+ unsigned char *digest;
+
+ if (!(hash = hash_find("sha256")) || !hash_init(hash, &ctx, &digest))
+ {
+ /* don't think this can ever happen. */
+ static unsigned char dummy[HASH_SIZE];
+ static int warned = 0;
+
+ if (warned)
+ my_syslog(LOG_ERR, _("Failed to create SHA-256 hash object"));
+ warned = 1;
+
+ return dummy;
+ }
+
+ for (q = ntohs(header->qdcount); q != 0; q--)
+ {
+ char *cp, c;
+
+ if (!extract_name(header, plen, &p, name, 1, 4))
+ break; /* bad packet */
+
+ for (cp = name; (c = *cp); cp++)
+ if (c >= 'A' && c <= 'Z')
+ *cp += 'a' - 'A';
+
+ hash->update(ctx, cp - name, (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;
+}
+
+#else /* HAVE_DNSSEC */
+
+#define SHA256_BLOCK_SIZE 32 // SHA256 outputs a 32 byte digest
+typedef unsigned char BYTE; // 8-bit byte
+typedef unsigned int WORD; // 32-bit word, change to "long" for 16-bit machines
+
+typedef struct {
+ BYTE data[64];
+ WORD datalen;
+ unsigned long long bitlen;
+ WORD state[8];
+} SHA256_CTX;
+
+static void sha256_init(SHA256_CTX *ctx);
+static void sha256_update(SHA256_CTX *ctx, const BYTE data[], size_t len);
+static void sha256_final(SHA256_CTX *ctx, BYTE hash[]);
+
+
+unsigned char *hash_questions(struct dns_header *header, size_t plen, char *name)
+{
+ int q;
+ unsigned char *p = (unsigned char *)(header+1);
+ SHA256_CTX ctx;
+ static BYTE digest[SHA256_BLOCK_SIZE];
+
+ sha256_init(&ctx);
+
+ for (q = ntohs(header->qdcount); q != 0; q--)
+ {
+ char *cp, c;
+
+ if (!extract_name(header, plen, &p, name, 1, 4))
+ break; /* bad packet */
+
+ for (cp = name; (c = *cp); cp++)
+ if (c >= 'A' && c <= 'Z')
+ *cp += 'a' - 'A';
+
+ sha256_update(&ctx, (BYTE *)name, cp - name);
+ /* CRC the class and type as well */
+ sha256_update(&ctx, (BYTE *)p, 4);
+
+ p += 4;
+ if (!CHECK_LEN(header, p, plen, 0))
+ break; /* bad packet */
+ }
+
+ sha256_final(&ctx, digest);
+ return (unsigned char *)digest;
+}
+
+/* Code from here onwards comes from https://github.com/B-Con/crypto-algorithms
+ and was written by Brad Conte (brad@bradconte.com), to whom all credit is given.
+
+ This code is in the public domain, and the copyright notice at the head of this
+ file does not apply to it.
+*/
+
+
+/****************************** MACROS ******************************/
+#define ROTLEFT(a,b) (((a) << (b)) | ((a) >> (32-(b))))
+#define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b))))
+
+#define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
+#define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
+#define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22))
+#define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25))
+#define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3))
+#define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10))
+
+/**************************** VARIABLES *****************************/
+static const WORD k[64] = {
+ 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
+ 0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
+ 0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
+ 0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
+ 0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
+ 0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
+ 0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
+ 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2
+};
+
+/*********************** FUNCTION DEFINITIONS ***********************/
+static void sha256_transform(SHA256_CTX *ctx, const BYTE data[])
+{
+ WORD a, b, c, d, e, f, g, h, i, j, t1, t2, m[64];
+
+ for (i = 0, j = 0; i < 16; ++i, j += 4)
+ m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]);
+ for ( ; i < 64; ++i)
+ m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16];
+
+ a = ctx->state[0];
+ b = ctx->state[1];
+ c = ctx->state[2];
+ d = ctx->state[3];
+ e = ctx->state[4];
+ f = ctx->state[5];
+ g = ctx->state[6];
+ h = ctx->state[7];
+
+ for (i = 0; i < 64; ++i)
+ {
+ t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i];
+ t2 = EP0(a) + MAJ(a,b,c);
+ h = g;
+ g = f;
+ f = e;
+ e = d + t1;
+ d = c;
+ c = b;
+ b = a;
+ a = t1 + t2;
+ }
+
+ ctx->state[0] += a;
+ ctx->state[1] += b;
+ ctx->state[2] += c;
+ ctx->state[3] += d;
+ ctx->state[4] += e;
+ ctx->state[5] += f;
+ ctx->state[6] += g;
+ ctx->state[7] += h;
+}
+
+static void sha256_init(SHA256_CTX *ctx)
+{
+ ctx->datalen = 0;
+ ctx->bitlen = 0;
+ ctx->state[0] = 0x6a09e667;
+ ctx->state[1] = 0xbb67ae85;
+ ctx->state[2] = 0x3c6ef372;
+ ctx->state[3] = 0xa54ff53a;
+ ctx->state[4] = 0x510e527f;
+ ctx->state[5] = 0x9b05688c;
+ ctx->state[6] = 0x1f83d9ab;
+ ctx->state[7] = 0x5be0cd19;
+}
+
+static void sha256_update(SHA256_CTX *ctx, const BYTE data[], size_t len)
+{
+ WORD i;
+
+ for (i = 0; i < len; ++i)
+ {
+ ctx->data[ctx->datalen] = data[i];
+ ctx->datalen++;
+ if (ctx->datalen == 64) {
+ sha256_transform(ctx, ctx->data);
+ ctx->bitlen += 512;
+ ctx->datalen = 0;
+ }
+ }
+}
+
+static void sha256_final(SHA256_CTX *ctx, BYTE hash[])
+{
+ WORD i;
+
+ i = ctx->datalen;
+
+ // Pad whatever data is left in the buffer.
+ if (ctx->datalen < 56)
+ {
+ ctx->data[i++] = 0x80;
+ while (i < 56)
+ ctx->data[i++] = 0x00;
+ }
+ else
+ {
+ ctx->data[i++] = 0x80;
+ while (i < 64)
+ ctx->data[i++] = 0x00;
+ sha256_transform(ctx, ctx->data);
+ memset(ctx->data, 0, 56);
+ }
+
+ // Append to the padding the total message's length in bits and transform.
+ ctx->bitlen += ctx->datalen * 8;
+ ctx->data[63] = ctx->bitlen;
+ ctx->data[62] = ctx->bitlen >> 8;
+ ctx->data[61] = ctx->bitlen >> 16;
+ ctx->data[60] = ctx->bitlen >> 24;
+ ctx->data[59] = ctx->bitlen >> 32;
+ ctx->data[58] = ctx->bitlen >> 40;
+ ctx->data[57] = ctx->bitlen >> 48;
+ ctx->data[56] = ctx->bitlen >> 56;
+ sha256_transform(ctx, ctx->data);
+
+ // Since this implementation uses little endian byte ordering and SHA uses big endian,
+ // reverse all the bytes when copying the final state to the output hash.
+ for (i = 0; i < 4; ++i)
+ {
+ hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff;
+ }
+}
+
+#endif