Fix packet authentication.

This wasn't working at all, since we didn't do HMAC but just a plain hash.
Also, verification of packets failed because it was checking the whole packet,
not the packet minus the HMAC.

diff --git a/src/gcrypt/digest.c b/src/gcrypt/digest.c
index 34f9d28..066600f 100644 (file)
--- a/src/gcrypt/digest.c
+++ b/src/gcrypt/digest.c
@@ -87,6 +87,7 @@ static bool digest_open(digest_t *digest, int algo, int maclength) {
                digest->maclength = maclength;
        
        digest->algo = algo;
+       digest->hmac = NULL;
 
        return true;
 }
@@ -118,24 +119,45 @@ bool digest_open_sha1(digest_t *digest, int maclength) {
 }
 
 void digest_close(digest_t *digest) {
+       if(digest->hmac)
+               gcry_md_close(digest->hmac);
+       digest->hmac = NULL;
+}
+
+bool digest_set_key(digest_t *digest, const void *key, size_t len) {
+       if(!digest->hmac)
+               gcry_md_open(&digest->hmac, digest->algo, GCRY_MD_FLAG_HMAC);
+       if(!digest->hmac)
+               return false;
+
+       return !gcry_md_setkey(digest->hmac, key, len);
 }
 
 bool digest_create(digest_t *digest, const void *indata, size_t inlen, void *outdata) {
        unsigned int len = gcry_md_get_algo_dlen(digest->algo);
-       char tmpdata[len];
 
-       gcry_md_hash_buffer(digest->algo, tmpdata, indata, inlen);
-       memcpy(outdata, tmpdata, digest->maclength);
+       if(digest->hmac) {
+               char *tmpdata;
+               gcry_md_reset(digest->hmac);
+               gcry_md_write(digest->hmac, indata, inlen);
+               tmpdata = gcry_md_read(digest->hmac, digest->algo);
+               if(!tmpdata)
+                       return false;
+               memcpy(outdata, tmpdata, digest->maclength);
+       } else {
+               char tmpdata[len];
+               gcry_md_hash_buffer(digest->algo, tmpdata, indata, inlen);
+               memcpy(outdata, tmpdata, digest->maclength);
+       }
 
        return true;
 }
 
 bool digest_verify(digest_t *digest, const void *indata, size_t inlen, const void *cmpdata) {
-       unsigned int len = gcry_md_get_algo_dlen(digest->algo);
+       unsigned int len = digest->maclength;
        char outdata[len];
 
-       gcry_md_hash_buffer(digest->algo, outdata, indata, inlen);
-       return !memcmp(cmpdata, outdata, digest->maclength);
+       return digest_create(digest, indata, inlen, outdata) && !memcmp(cmpdata, outdata, len);
 }
 
 int digest_get_nid(const digest_t *digest) {

diff --git a/src/gcrypt/digest.h b/src/gcrypt/digest.h
index f70fecc..1188496 100644 (file)
--- a/src/gcrypt/digest.h
+++ b/src/gcrypt/digest.h
@@ -28,6 +28,7 @@ typedef struct digest {
        int algo;
        int nid;
        int maclength;
+       gcry_md_hd_t hmac;
 } digest_t;
 
 extern bool digest_open_by_name(struct digest *, const char *name, int maclength);
@@ -36,6 +37,7 @@ extern bool digest_open_sha1(struct digest *, int maclength);
 extern void digest_close(struct digest *);
 extern bool digest_create(struct digest *, const void *indata, size_t inlen, void *outdata);
 extern bool digest_verify(struct digest *, const void *indata, size_t inlen, const void *digestdata);
+extern bool digest_set_key(struct digest *, const void *key, size_t len);
 extern int digest_get_nid(const struct digest *);
 extern size_t digest_length(const struct digest *);
 extern bool digest_active(const struct digest *);

diff --git a/src/net_packet.c b/src/net_packet.c
index aaa0c72..df6f482 100644 (file)
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -195,7 +195,7 @@ static bool try_mac(node_t *n, const vpn_packet_t *inpkt) {
        if(!digest_active(&n->indigest) || inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest))
                return false;
 
-       return digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len);
+       return digest_verify(&n->indigest, &inpkt->seqno, inpkt->len - n->indigest.maclength, (const char *)&inpkt->seqno + inpkt->len - n->indigest.maclength);
 }
 
 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
@@ -222,11 +222,13 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 
        /* Check the message authentication code */
 
-       if(digest_active(&n->indigest) && !digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len)) {
-               ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)", n->name, n->hostname);
-               return;
+       if(digest_active(&n->indigest)) {
+               inpkt->len -= n->indigest.maclength;
+               if(!digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len)) {
+                       ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)", n->name, n->hostname);
+                       return;
+               }
        }
-
        /* Decrypt the packet */
 
        if(cipher_active(&n->incipher)) {
@@ -501,31 +503,28 @@ void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 
 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
        splay_node_t *node;
-       edge_t *e;
-       node_t *n = NULL;
+       node_t *n, *found = NULL;
        static time_t last_hard_try = 0;
        time_t now = time(NULL);
 
-       for(node = edge_weight_tree->head; node; node = node->next) {
-               e = node->data;
-
-               if(sockaddrcmp_noport(from, &e->address)) {
-                       if(last_hard_try == now)
-                               continue;
-                       last_hard_try = now;
-               }
+       if(last_hard_try == now)
+               return NULL;
+       else
+               last_hard_try = now;
 
-               if(!n)
-                       n = e->to;
+       for(node = node_tree->head; node; node = node->next) {
+               n = node->data;
 
-               if(!try_mac(e->to, pkt))
+               if(n == myself || !digest_active(&n->indigest))
                        continue;
 
-               n = e->to;
-               break;
+               if(try_mac(n, pkt)) {
+                       found = n;
+                       break;
+               }
        }
 
-       return n;
+       return found;
 }
 
 void handle_incoming_vpn_data(int sock, short events, void *data) {

diff --git a/src/openssl/digest.c b/src/openssl/digest.c
index ff350da..f20a975 100644 (file)
--- a/src/openssl/digest.c
+++ b/src/openssl/digest.c
@@ -18,8 +18,11 @@
 */
 
 #include "system.h"
+#include "utils.h"
+#include "xalloc.h"
 
 #include <openssl/err.h>
+#include <openssl/hmac.h>
 
 #include "digest.h"
 #include "logger.h"
@@ -35,6 +38,7 @@ static void set_maclength(digest_t *digest, int maclength) {
 
 bool digest_open_by_name(digest_t *digest, const char *name, int maclength) {
        digest->digest = EVP_get_digestbyname(name);
+       digest->key = NULL;
 
        if(!digest->digest) {
                logger(LOG_DEBUG, "Unknown digest name '%s'!", name);
@@ -47,6 +51,7 @@ bool digest_open_by_name(digest_t *digest, const char *name, int maclength) {
 
 bool digest_open_by_nid(digest_t *digest, int nid, int maclength) {
        digest->digest = EVP_get_digestbynid(nid);
+       digest->key = NULL;
 
        if(!digest->digest) {
                logger(LOG_DEBUG, "Unknown digest nid %d!", nid);
@@ -59,25 +64,39 @@ bool digest_open_by_nid(digest_t *digest, int nid, int maclength) {
 
 bool digest_open_sha1(digest_t *digest, int maclength) {
        digest->digest = EVP_sha1();
+       digest->key = NULL;
 
        set_maclength(digest, maclength);
        return true;
 }
 
+bool digest_set_key(digest_t *digest, const void *key, size_t len) {
+       digest->key = xrealloc(digest->key, len);
+       memcpy(digest->key, key, len);
+       digest->keylength = len;
+}
+
 void digest_close(digest_t *digest) {
+       if(digest->key)
+               free(digest->key);
+       digest->key = NULL;
 }
 
 bool digest_create(digest_t *digest, const void *indata, size_t inlen, void *outdata) {
        size_t len = EVP_MD_size(digest->digest);
        unsigned char tmpdata[len];
 
-       EVP_MD_CTX ctx;
-
-       if(!EVP_DigestInit(&ctx, digest->digest)
-                       || !EVP_DigestUpdate(&ctx, indata, inlen)
-                       || !EVP_DigestFinal(&ctx, tmpdata, NULL)) {
-               logger(LOG_DEBUG, "Error creating digest: %s", ERR_error_string(ERR_get_error(), NULL));
-               return false;
+       if(digest->key) {
+               HMAC(digest->digest, digest->key, digest->keylength, indata, inlen, tmpdata, NULL);
+       } else {
+               EVP_MD_CTX ctx;
+
+               if(!EVP_DigestInit(&ctx, digest->digest)
+                               || !EVP_DigestUpdate(&ctx, indata, inlen)
+                               || !EVP_DigestFinal(&ctx, tmpdata, NULL)) {
+                       logger(LOG_DEBUG, "Error creating digest: %s", ERR_error_string(ERR_get_error(), NULL));
+                       return false;
+               }
        }
 
        memcpy(outdata, tmpdata, digest->maclength);
@@ -85,7 +104,7 @@ bool digest_create(digest_t *digest, const void *indata, size_t inlen, void *out
 }
 
 bool digest_verify(digest_t *digest, const void *indata, size_t inlen, const void *cmpdata) {
-       size_t len = EVP_MD_size(digest->digest);
+       size_t len = digest->maclength;
        unsigned char outdata[len];
 
        return digest_create(digest, indata, inlen, outdata) && !memcmp(cmpdata, outdata, digest->maclength);

diff --git a/src/openssl/digest.h b/src/openssl/digest.h
index 258bcf6..f3855c9 100644 (file)
--- a/src/openssl/digest.h
+++ b/src/openssl/digest.h
@@ -27,6 +27,8 @@
 typedef struct digest {
        const EVP_MD *digest;
        int maclength;
+       int keylength;
+       char *key;
 } digest_t;
 
 extern bool digest_open_by_name(struct digest *, const char *name, int maclength);
@@ -35,6 +37,7 @@ extern bool digest_open_sha1(struct digest *, int maclength);
 extern void digest_close(struct digest *);
 extern bool digest_create(struct digest *, const void *indata, size_t inlen, void *outdata);
 extern bool digest_verify(struct digest *, const void *indata, size_t inlen, const void *digestdata);
+extern bool digest_set_key(struct digest *, const void *key, size_t len);
 extern int digest_get_nid(const struct digest *);
 extern size_t digest_length(const struct digest *);
 extern bool digest_active(const struct digest *);

diff --git a/src/protocol_key.c b/src/protocol_key.c
index aae5516..3b02267 100644 (file)
--- a/src/protocol_key.c
+++ b/src/protocol_key.c
@@ -139,6 +139,7 @@ bool send_ans_key(node_t *to) {
 
        randomize(key, keylen);
        cipher_set_key(&to->incipher, key, true);
+       digest_set_key(&to->indigest, key, keylen);
 
        bin2hex(key, key, keylen);
        key[keylen * 2] = '\0';
@@ -160,7 +161,7 @@ bool ans_key_h(connection_t *c, char *request) {
        char from_name[MAX_STRING_SIZE];
        char to_name[MAX_STRING_SIZE];
        char key[MAX_STRING_SIZE];
-       int cipher, digest, maclength, compression;
+       int cipher, digest, maclength, compression, keylen;
        node_t *from, *to;
 
        if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d",
@@ -209,7 +210,9 @@ bool ans_key_h(connection_t *c, char *request) {
                return false;
        }
 
-       if(strlen(key) / 2 != cipher_keylength(&from->outcipher)) {
+       keylen = strlen(key) / 2;
+
+       if(keylen != cipher_keylength(&from->outcipher)) {
                logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
                return false;
        }
@@ -233,8 +236,9 @@ bool ans_key_h(connection_t *c, char *request) {
 
        /* Update our copy of the origin's packet key */
 
-       hex2bin(key, key, cipher_keylength(&from->outcipher));
+       hex2bin(key, key, keylen);
        cipher_set_key(&from->outcipher, key, false);
+       digest_set_key(&from->outdigest, key, keylen);
 
        from->status.validkey = true;
        from->status.waitingforkey = false;