[Feature] Implement rdns-curve plugin based on rspamd cryptobox

contrib/librdns/CMakeLists.txt

@@ -7,4 +7,5 @@ SET(LIBRDNSSRC			util.c
 						packet.c
 						resolver.c)
 
-ADD_LIBRARY(rdns STATIC ${LIBRDNSSRC})
+ADD_LIBRARY(rdns STATIC ${LIBRDNSSRC})
+SET_TARGET_PROPERTIES(rdns PROPERTIES COMPILE_FLAGS "-DUSE_RSPAMD_CRYPTOBOX")

contrib/librdns/curve.c

@@ -441,7 +441,408 @@ rdns_curve_dtor (struct rdns_resolver *resolver, void *plugin_data)
 	}
 	REF_RELEASE (ctx->cur_key);
 }
+#elif defined(USE_RSPAMD_CRYPTOBOX)
 
+#include "cryptobox.h"
+
+#define crypto_box_ZEROBYTES 32
+#define crypto_box_BOXZEROBYTES 16
+
+ssize_t rdns_curve_send (struct rdns_request *req, void *plugin_data);
+ssize_t rdns_curve_recv (struct rdns_io_channel *ioc, void *buf, size_t len,
+		void *plugin_data, struct rdns_request **req_out);
+void rdns_curve_finish_request (struct rdns_request *req, void *plugin_data);
+void rdns_curve_dtor (struct rdns_resolver *resolver, void *plugin_data);
+
+struct rdns_curve_entry {
+	char *name;
+	rspamd_pk_t pk;
+	UT_hash_handle hh;
+};
+
+struct rdns_curve_nm_entry {
+	rspamd_nm_t k;
+	struct rdns_curve_entry *entry;
+	struct rdns_curve_nm_entry *prev, *next;
+};
+
+struct rdns_curve_client_key {
+	rspamd_pk_t pk;
+	rspamd_sk_t sk;
+	struct rdns_curve_nm_entry *nms;
+	uint64_t counter;
+	unsigned int uses;
+	ref_entry_t ref;
+};
+
+struct rdns_curve_request {
+	struct rdns_request *req;
+	struct rdns_curve_client_key *key;
+	struct rdns_curve_entry *entry;
+	struct rdns_curve_nm_entry *nm;
+	rspamd_nonce_t nonce;
+	UT_hash_handle hh;
+};
+
+struct rdns_curve_ctx {
+	struct rdns_curve_entry *entries;
+	struct rdns_curve_client_key *cur_key;
+	struct rdns_curve_request *requests;
+	double key_refresh_interval;
+	void *key_refresh_event;
+	struct rdns_resolver *resolver;
+};
+
+static struct rdns_curve_client_key *
+rdns_curve_client_key_new (struct rdns_curve_ctx *ctx)
+{
+	struct rdns_curve_client_key *new;
+	struct rdns_curve_nm_entry *nm;
+	struct rdns_curve_entry *entry, *tmp;
+
+	new = calloc (1, sizeof (struct rdns_curve_client_key));
+	rspamd_cryptobox_keypair (new->pk, new->sk, RSPAMD_CRYPTOBOX_MODE_25519);
+
+	HASH_ITER (hh, ctx->entries, entry, tmp) {
+		nm = calloc (1, sizeof (struct rdns_curve_nm_entry));
+		nm->entry = entry;
+		rspamd_cryptobox_nm (nm->k, entry->pk, new->sk,
+				RSPAMD_CRYPTOBOX_MODE_25519);
+
+		DL_APPEND (new->nms, nm);
+	}
+
+	new->counter = ottery_rand_uint64 ();
+
+	return new;
+}
+
+static struct rdns_curve_nm_entry *
+rdns_curve_find_nm (struct rdns_curve_client_key *key, struct rdns_curve_entry *entry)
+{
+	struct rdns_curve_nm_entry *nm;
+
+	DL_FOREACH (key->nms, nm) {
+		if (nm->entry == entry) {
+			return nm;
+		}
+	}
+
+	return NULL;
+}
+
+static void
+rdns_curve_client_key_free (struct rdns_curve_client_key *key)
+{
+	struct rdns_curve_nm_entry *nm, *tmp;
+
+	DL_FOREACH_SAFE (key->nms, nm, tmp) {
+		rspamd_explicit_memzero (nm->k, sizeof (nm->k));
+		free (nm);
+	}
+
+	rspamd_explicit_memzero (key->sk, sizeof (key->sk));
+	free (key);
+}
+
+struct rdns_curve_ctx*
+rdns_curve_ctx_new (double key_refresh_interval)
+{
+	struct rdns_curve_ctx *new;
+
+	new = calloc (1, sizeof (struct rdns_curve_ctx));
+	new->key_refresh_interval = key_refresh_interval;
+
+	return new;
+}
+
+void
+rdns_curve_ctx_add_key (struct rdns_curve_ctx *ctx,
+		const char *name, const unsigned char *pubkey)
+{
+	struct rdns_curve_entry *entry;
+	bool success = true;
+
+	entry = malloc (sizeof (struct rdns_curve_entry));
+	if (entry != NULL) {
+		entry->name = strdup (name);
+		if (entry->name == NULL) {
+			success = false;
+		}
+		memcpy (entry->pk, pubkey, sizeof (entry->pk));
+		if (success) {
+			HASH_ADD_KEYPTR (hh, ctx->entries, entry->name, strlen (entry->name), entry);
+		}
+	}
+}
+
+#define rdns_curve_write_hex(in, out, offset, base) do {					\
+    *(out) |= ((in)[(offset)] - (base)) << ((1 - offset) * 4);				\
+} while (0)
+
+static bool
+rdns_curve_hex_to_byte (const char *in, unsigned char *out)
+{
+	int i;
+
+	for (i = 0; i <= 1; i ++) {
+		if (in[i] >= '0' && in[i] <= '9') {
+			rdns_curve_write_hex (in, out, i, '0');
+		}
+		else if (in[i] >= 'a' && in[i] <= 'f') {
+			rdns_curve_write_hex (in, out, i, 'a' - 10);
+		}
+		else if (in[i] >= 'A' && in[i] <= 'F') {
+			rdns_curve_write_hex (in, out, i, 'A' - 10);
+		}
+		else {
+			return false;
+		}
+	}
+	return true;
+}
+
+#undef rdns_curve_write_hex
+
+unsigned char *
+rdns_curve_key_from_hex (const char *hex)
+{
+	unsigned int len = strlen (hex), i;
+	unsigned char *res = NULL;
+
+	if (len == rspamd_cryptobox_pk_bytes (RSPAMD_CRYPTOBOX_MODE_25519) * 2) {
+		res = calloc (1, rspamd_cryptobox_pk_bytes (RSPAMD_CRYPTOBOX_MODE_25519));
+		for (i = 0;
+				i < rspamd_cryptobox_pk_bytes (RSPAMD_CRYPTOBOX_MODE_25519);
+				i ++) {
+			if (!rdns_curve_hex_to_byte (&hex[i * 2], &res[i])) {
+				free (res);
+				return NULL;
+			}
+		}
+	}
+
+	return res;
+}
+
+void
+rdns_curve_ctx_destroy (struct rdns_curve_ctx *ctx)
+{
+	struct rdns_curve_entry *entry, *tmp;
+
+	HASH_ITER (hh, ctx->entries, entry, tmp) {
+		free (entry->name);
+		free (entry);
+	}
+
+	free (ctx);
+}
+
+static void
+rdns_curve_refresh_key_callback (void *user_data)
+{
+	struct rdns_curve_ctx *ctx = user_data;
+	struct rdns_resolver *resolver;
+
+	resolver = ctx->resolver;
+	rdns_info ("refresh dnscurve keys");
+	REF_RELEASE (ctx->cur_key);
+	ctx->cur_key = rdns_curve_client_key_new (ctx);
+	REF_INIT_RETAIN (ctx->cur_key, rdns_curve_client_key_free);
+}
+
+void
+rdns_curve_register_plugin (struct rdns_resolver *resolver,
+		struct rdns_curve_ctx *ctx)
+{
+	struct rdns_plugin *plugin;
+
+	if (!resolver->async_binded) {
+		return;
+	}
+
+	plugin = calloc (1, sizeof (struct rdns_plugin));
+	if (plugin != NULL) {
+		plugin->data = ctx;
+		plugin->type = RDNS_PLUGIN_CURVE;
+		plugin->cb.curve_plugin.send_cb = rdns_curve_send;
+		plugin->cb.curve_plugin.recv_cb = rdns_curve_recv;
+		plugin->cb.curve_plugin.finish_cb = rdns_curve_finish_request;
+		plugin->dtor = rdns_curve_dtor;
+		ctx->cur_key = rdns_curve_client_key_new (ctx);
+		REF_INIT_RETAIN (ctx->cur_key, rdns_curve_client_key_free);
+
+		if (ctx->key_refresh_interval > 0) {
+			ctx->key_refresh_event = resolver->async->add_periodic (
+					resolver->async->data, ctx->key_refresh_interval,
+					rdns_curve_refresh_key_callback, ctx);
+		}
+		ctx->resolver = resolver;
+		rdns_resolver_register_plugin (resolver, plugin);
+	}
+}
+
+ssize_t
+rdns_curve_send (struct rdns_request *req, void *plugin_data)
+{
+	struct rdns_curve_ctx *ctx = (struct rdns_curve_ctx *)plugin_data;
+	struct rdns_curve_entry *entry;
+	struct iovec iov[4];
+	unsigned char *m;
+	static const char qmagic[] = "Q6fnvWj8";
+	struct rdns_curve_request *creq;
+	struct rdns_curve_nm_entry *nm;
+	ssize_t ret, boxed_len;
+
+	/* Check for key */
+	HASH_FIND_STR (ctx->entries, req->io->srv->name, entry);
+	if (entry != NULL) {
+		nm = rdns_curve_find_nm (ctx->cur_key, entry);
+		creq = malloc (sizeof (struct rdns_curve_request));
+		if (creq == NULL) {
+			return -1;
+		}
+
+		boxed_len = req->pos + crypto_box_ZEROBYTES;
+		m = malloc (boxed_len);
+		if (m == NULL) {
+			return -1;
+		}
+
+		/* Ottery is faster than sodium native PRG that uses /dev/random only */
+		memcpy (creq->nonce, &ctx->cur_key->counter, sizeof (uint64_t));
+		ottery_rand_bytes (creq->nonce + sizeof (uint64_t), 12 - sizeof (uint64_t));
+		rspamd_explicit_memzero (creq->nonce + 12,
+				rspamd_cryptobox_nonce_bytes (RSPAMD_CRYPTOBOX_MODE_25519) - 12);
+
+		rspamd_explicit_memzero (m, crypto_box_ZEROBYTES);
+		memcpy (m + crypto_box_ZEROBYTES, req->packet, req->pos);
+
+		rspamd_cryptobox_encrypt_nm_inplace (m + crypto_box_ZEROBYTES,
+				boxed_len,
+				creq->nonce,
+				nm->k,
+				m,
+				RSPAMD_CRYPTOBOX_MODE_25519);
+
+		creq->key = ctx->cur_key;
+		REF_RETAIN (ctx->cur_key);
+		creq->entry = entry;
+		creq->req = req;
+		creq->nm = nm;
+		HASH_ADD_KEYPTR (hh, ctx->requests, creq->nonce, 12, creq);
+		req->curve_plugin_data = creq;
+
+		ctx->cur_key->counter ++;
+		ctx->cur_key->uses ++;
+
+		/* Now form a dnscurve packet */
+		iov[0].iov_base = (void *)qmagic;
+		iov[0].iov_len = sizeof (qmagic) - 1;
+		iov[1].iov_base = ctx->cur_key->pk;
+		iov[1].iov_len = sizeof (ctx->cur_key->pk);
+		iov[2].iov_base = creq->nonce;
+		iov[2].iov_len = 12;
+		iov[3].iov_base = m + crypto_box_BOXZEROBYTES;
+		iov[3].iov_len = boxed_len - crypto_box_BOXZEROBYTES;
+
+		ret = writev (req->io->sock, iov, sizeof (iov) / sizeof (iov[0]));
+		rspamd_explicit_memzero (m, boxed_len);
+		free (m);
+	}
+	else {
+		ret = write (req->io->sock, req->packet, req->pos);
+		req->curve_plugin_data = NULL;
+	}
+
+	return ret;
+}
+
+ssize_t
+rdns_curve_recv (struct rdns_io_channel *ioc, void *buf, size_t len, void *plugin_data,
+		struct rdns_request **req_out)
+{
+	struct rdns_curve_ctx *ctx = (struct rdns_curve_ctx *)plugin_data;
+	ssize_t ret, boxlen;
+	static const char rmagic[] = "R6fnvWJ8";
+	unsigned char *p, *box;
+	unsigned char enonce[24];
+	struct rdns_curve_request *creq;
+	struct rdns_resolver *resolver;
+
+	resolver = ctx->resolver;
+	ret = read (ioc->sock, buf, len);
+
+	if (ret <= 0 || ret < 64) {
+		/* Definitely not a DNSCurve packet */
+		return ret;
+	}
+
+	if (memcmp (buf, rmagic, sizeof (rmagic) - 1) == 0) {
+		/* Likely DNSCurve packet */
+		p = ((unsigned char *)buf) + 8;
+		HASH_FIND (hh, ctx->requests, p, 12, creq);
+		if (creq == NULL) {
+			rdns_info ("unable to find nonce in the internal hash");
+			return ret;
+		}
+
+		memcpy (enonce, p, rspamd_cryptobox_nonce_bytes (RSPAMD_CRYPTOBOX_MODE_25519));
+		p += rspamd_cryptobox_nonce_bytes (RSPAMD_CRYPTOBOX_MODE_25519);
+		boxlen = ret - rspamd_cryptobox_nonce_bytes (RSPAMD_CRYPTOBOX_MODE_25519) +
+				crypto_box_BOXZEROBYTES -
+				sizeof (rmagic) + 1;
+		if (boxlen < 0) {
+			return ret;
+		}
+
+		box = malloc (boxlen);
+		rspamd_explicit_memzero (box, crypto_box_BOXZEROBYTES);
+		memcpy (box + crypto_box_BOXZEROBYTES, p,
+				boxlen - crypto_box_BOXZEROBYTES);
+
+		if (!rspamd_cryptobox_decrypt_nm_inplace (
+				box + rspamd_cryptobox_mac_bytes (RSPAMD_CRYPTOBOX_MODE_25519),
+				boxlen - rspamd_cryptobox_mac_bytes (RSPAMD_CRYPTOBOX_MODE_25519),
+				enonce, creq->nm->k, box, RSPAMD_CRYPTOBOX_MODE_25519)) {
+			memcpy (buf, box + crypto_box_ZEROBYTES,
+					boxlen - crypto_box_ZEROBYTES);
+			ret = boxlen - crypto_box_ZEROBYTES;
+			*req_out = creq->req;
+		}
+		else {
+			rdns_info ("unable open cryptobox of size %d", (int)boxlen);
+		}
+
+		free (box);
+	}
+
+	return ret;
+}
+
+void
+rdns_curve_finish_request (struct rdns_request *req, void *plugin_data)
+{
+	struct rdns_curve_ctx *ctx = (struct rdns_curve_ctx *)plugin_data;
+	struct rdns_curve_request *creq = req->curve_plugin_data;
+
+	if (creq != NULL) {
+		REF_RELEASE (creq->key);
+		HASH_DELETE (hh, ctx->requests, creq);
+	}
+}
+
+void
+rdns_curve_dtor (struct rdns_resolver *resolver, void *plugin_data)
+{
+	struct rdns_curve_ctx *ctx = (struct rdns_curve_ctx *)plugin_data;
+
+	if (ctx->key_refresh_event != NULL) {
+		resolver->async->del_periodic (resolver->async->data,
+				ctx->key_refresh_event);
+	}
+	REF_RELEASE (ctx->cur_key);
+}
 #else
 
 /* Fake functions */

contrib/librdns/dns_private.h

@@ -86,7 +86,7 @@ struct rdns_request {
 
 	void *async_event;
 
-#ifdef TWEETNACL
+#if defined(TWEETNACL) || defined(USE_RSPAMD_CRYPTOBOX)
 	void *curve_plugin_data;
 #endif