Refactor crypto RNG; add getrandom() support

[tinc] / src / sptps.c

diff --git a/src/sptps.c b/src/sptps.c
index 6ad1c8d..a0483c3 100644 (file)
--- a/src/sptps.c
+++ b/src/sptps.c
@@ -21,12 +21,12 @@
 #include "system.h"
 
 #include "chacha-poly1305/chacha-poly1305.h"
-#include "crypto.h"
 #include "ecdh.h"
 #include "ecdsa.h"
 #include "logger.h"
 #include "prf.h"
 #include "sptps.h"
+#include "random.h"
 
 unsigned int sptps_replaywin = 16;
 
@@ -92,7 +92,7 @@ static void warning(sptps_t *s, const char *format, ...) {
 
 // Send a record (datagram version, accepts all record types, handles encryption and authentication).
 static bool send_record_priv_datagram(sptps_t *s, uint8_t type, const void *data, uint16_t len) {
-       uint8_t buffer[len + 21UL];
+       uint8_t *buffer = alloca(len + 21UL);
 
        // Create header with sequence number, length and record type
        uint32_t seqno = s->outseqno++;
@@ -117,7 +117,7 @@ static bool send_record_priv(sptps_t *s, uint8_t type, const void *data, uint16_
                return send_record_priv_datagram(s, type, data, len);
        }
 
-       uint8_t buffer[len + 19UL];
+       uint8_t *buffer = alloca(len + 19UL);
 
        // Create header with sequence number, length and record type
        uint32_t seqno = s->outseqno++;
@@ -187,8 +187,9 @@ static bool send_sig(sptps_t *s) {
        size_t siglen = ecdsa_size(s->mykey);
 
        // Concatenate both KEX messages, plus tag indicating if it is from the connection originator, plus label
-       uint8_t msg[(1 + 32 + keylen) * 2 + 1 + s->labellen];
-       uint8_t sig[siglen];
+       const size_t msglen = (1 + 32 + keylen) * 2 + 1 + s->labellen;
+       uint8_t *msg = alloca(msglen);
+       uint8_t *sig = alloca(siglen);
 
        msg[0] = s->initiator;
        memcpy(msg + 1, s->mykex, 1 + 32 + keylen);
@@ -196,16 +197,16 @@ static bool send_sig(sptps_t *s) {
        memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
 
        // Sign the result.
-       if(!ecdsa_sign(s->mykey, msg, sizeof(msg), sig)) {
+       if(!ecdsa_sign(s->mykey, msg, msglen, sig)) {
                return error(s, EINVAL, "Failed to sign SIG record");
        }
 
        // Send the SIG exchange record.
-       return send_record_priv(s, SPTPS_HANDSHAKE, sig, sizeof(sig));
+       return send_record_priv(s, SPTPS_HANDSHAKE, sig, siglen);
 }
 
 // Generate key material from the shared secret created from the ECDHE key exchange.
-static bool generate_key_material(sptps_t *s, const char *shared, size_t len) {
+static bool generate_key_material(sptps_t *s, const uint8_t *shared, size_t len) {
        // Initialise cipher and digest structures if necessary
        if(!s->outstate) {
                s->incipher = chacha_poly1305_init();
@@ -226,7 +227,7 @@ static bool generate_key_material(sptps_t *s, const char *shared, size_t len) {
        }
 
        // Create the HMAC seed, which is "key expansion" + session label + server nonce + client nonce
-       char seed[s->labellen + 64 + 13];
+       uint8_t *seed = alloca(s->labellen + 64 + 13);
        memcpy(seed, "key expansion", 13);
 
        if(s->initiator) {
@@ -317,7 +318,8 @@ static bool receive_sig(sptps_t *s, const uint8_t *data, uint16_t len) {
        }
 
        // Concatenate both KEX messages, plus tag indicating if it is from the connection originator
-       uint8_t msg[(1 + 32 + keylen) * 2 + 1 + s->labellen];
+       const size_t msglen = (1 + 32 + keylen) * 2 + 1 + s->labellen;
+       uint8_t *msg = alloca(msglen);
 
        msg[0] = !s->initiator;
        memcpy(msg + 1, s->hiskex, 1 + 32 + keylen);
@@ -325,12 +327,12 @@ static bool receive_sig(sptps_t *s, const uint8_t *data, uint16_t len) {
        memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
 
        // Verify signature.
-       if(!ecdsa_verify(s->hiskey, msg, sizeof(msg), data)) {
+       if(!ecdsa_verify(s->hiskey, msg, msglen, data)) {
                return error(s, EIO, "Failed to verify SIG record");
        }
 
        // Compute shared secret.
-       char shared[ECDH_SHARED_SIZE];
+       uint8_t shared[ECDH_SHARED_SIZE];
 
        if(!ecdh_compute_shared(s->ecdh, s->hiskex + 1 + 32, shared)) {
                return error(s, EINVAL, "Failed to compute ECDH shared secret");
@@ -513,7 +515,7 @@ bool sptps_verify_datagram(sptps_t *s, const void *vdata, size_t len) {
                return error(s, EIO, "Received short packet");
        }
 
-       const char *data = vdata;
+       const uint8_t *data = vdata;
        uint32_t seqno;
        memcpy(&seqno, data, 4);
        seqno = ntohl(seqno);
@@ -522,7 +524,7 @@ bool sptps_verify_datagram(sptps_t *s, const void *vdata, size_t len) {
                return false;
        }
 
-       char buffer[len];
+       uint8_t *buffer = alloca(len);
        size_t outlen;
        return chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen);
 }
@@ -558,7 +560,7 @@ static bool sptps_receive_data_datagram(sptps_t *s, const uint8_t *data, size_t
 
        // Decrypt
 
-       uint8_t buffer[len];
+       uint8_t *buffer = alloca(len);
        size_t outlen;
 
        if(!chacha_poly1305_decrypt(s->incipher, seqno, data, len, buffer, &outlen)) {