SSH2 MACs now use dynamically allocated contexts.

[originally from svn r2131]

ssh.c

@@ -371,19 +371,28 @@ const static struct ssh_kex *kex_algs[] = {
 
 const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
 
-static void nullmac_key(unsigned char *key)
+static void *nullmac_make_context(void)
+{
+    return NULL;
+}
+static void nullmac_free_context(void *handle)
 {
 }
-static void nullmac_generate(unsigned char *blk, int len,
+static void nullmac_key(void *handle, unsigned char *key)
+{
+}
+static void nullmac_generate(void *handle, unsigned char *blk, int len,
 			     unsigned long seq)
 {
 }
-static int nullmac_verify(unsigned char *blk, int len, unsigned long seq)
+static int nullmac_verify(void *handle, unsigned char *blk, int len,
+			  unsigned long seq)
 {
     return 1;
 }
 const static struct ssh_mac ssh_mac_none = {
-    nullmac_key, nullmac_key, nullmac_generate, nullmac_verify, "none", 0
+    nullmac_make_context, nullmac_free_context, nullmac_key,
+    nullmac_generate, nullmac_verify, "none", 0
 };
 const static struct ssh_mac *macs[] = {
     &ssh_sha1, &ssh_md5, &ssh_mac_none
@@ -554,6 +563,7 @@ struct ssh_tag {
     const struct ssh2_cipher *cscipher, *sccipher;
     void *cs_cipher_ctx, *sc_cipher_ctx;
     const struct ssh_mac *csmac, *scmac;
+    void *cs_mac_ctx, *sc_mac_ctx;
     const struct ssh_compress *cscomp, *sccomp;
     const struct ssh_kex *kex;
     const struct ssh_signkey *hostkey;
@@ -979,7 +989,7 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      * Check the MAC.
      */
     if (ssh->scmac
-	&& !ssh->scmac->verify(ssh->pktin.data, st->len + 4,
+	&& !ssh->scmac->verify(ssh->sc_mac_ctx, ssh->pktin.data, st->len + 4,
 			       st->incoming_sequence)) {
 	bombout(("Incorrect MAC received on packet"));
 	crReturn(0);
@@ -1468,7 +1478,8 @@ static int ssh2_pkt_construct(Ssh ssh)
 	ssh->pktout.data[ssh->pktout.length + i] = random_byte();
     PUT_32BIT(ssh->pktout.data, ssh->pktout.length + padding - 4);
     if (ssh->csmac)
-	ssh->csmac->generate(ssh->pktout.data, ssh->pktout.length + padding,
+	ssh->csmac->generate(ssh->cs_mac_ctx, ssh->pktout.data,
+			     ssh->pktout.length + padding,
 			     ssh->v2_outgoing_sequence);
     ssh->v2_outgoing_sequence++;       /* whether or not we MACed */
 
@@ -4031,12 +4042,22 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	ssh->cscipher->free_context(ssh->cs_cipher_ctx);
     ssh->cscipher = s->cscipher_tobe;
     ssh->cs_cipher_ctx = ssh->cscipher->make_context();
+
     if (ssh->sc_cipher_ctx)
 	ssh->sccipher->free_context(ssh->sc_cipher_ctx);
     ssh->sccipher = s->sccipher_tobe;
     ssh->sc_cipher_ctx = ssh->sccipher->make_context();
+
+    if (ssh->cs_mac_ctx)
+	ssh->csmac->free_context(ssh->cs_mac_ctx);
     ssh->csmac = s->csmac_tobe;
+    ssh->cs_mac_ctx = ssh->csmac->make_context();
+
+    if (ssh->sc_mac_ctx)
+	ssh->scmac->free_context(ssh->sc_mac_ctx);
     ssh->scmac = s->scmac_tobe;
+    ssh->sc_mac_ctx = ssh->scmac->make_context();
+
     ssh->cscomp = s->cscomp_tobe;
     ssh->sccomp = s->sccomp_tobe;
     ssh->cscomp->compress_init();
@@ -4059,9 +4080,9 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'B',keyspace);
 	ssh->sccipher->setiv(ssh->sc_cipher_ctx, keyspace);
 	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'E',keyspace);
-	ssh->csmac->setcskey(keyspace);
+	ssh->csmac->setkey(ssh->cs_mac_ctx, keyspace);
 	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'F',keyspace);
-	ssh->scmac->setsckey(keyspace);
+	ssh->scmac->setkey(ssh->sc_mac_ctx, keyspace);
     }
     {
 	char buf[256];
@@ -5785,7 +5806,9 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->sccipher = NULL;
     ssh->sc_cipher_ctx = NULL;
     ssh->csmac = NULL;
+    ssh->sc_mac_ctx = NULL;
     ssh->scmac = NULL;
+    ssh->sc_mac_ctx = NULL;
     ssh->cscomp = NULL;
     ssh->sccomp = NULL;
     ssh->kex = NULL;

ssh.h

@@ -151,10 +151,11 @@ struct ssh2_ciphers {
 };
 
 struct ssh_mac {
-    void (*setcskey) (unsigned char *key);
+    void *(*make_context)(void);
-    void (*setsckey) (unsigned char *key);
+    void (*free_context)(void *);
-    void (*generate) (unsigned char *blk, int len, unsigned long seq);
+    void (*setkey) (void *, unsigned char *key);
-    int (*verify) (unsigned char *blk, int len, unsigned long seq);
+    void (*generate) (void *, unsigned char *blk, int len, unsigned long seq);
+    int (*verify) (void *, unsigned char *blk, int len, unsigned long seq);
     char *name;
     int len;
 };

sshmd5.c

@@ -208,44 +208,46 @@ void MD5Final(unsigned char output[16], struct MD5Context *s)
  * HMAC wrapper on it.
  */
 
-static struct MD5Context md5_cs_mac_s1, md5_cs_mac_s2;
+static void *md5_make_context(void)
-static struct MD5Context md5_sc_mac_s1, md5_sc_mac_s2;
-
-static void md5_key(struct MD5Context *s1, struct MD5Context *s2,
-		    unsigned char *key, int len)
 {
+    return smalloc(2*sizeof(struct MD5Context));
+}
+
+static void md5_free_context(void *handle)
+{
+    sfree(handle);
+}
+
+static void md5_key_internal(void *handle, unsigned char *key, int len)
+{
+    struct MD5Context *keys = (struct MD5Context *)handle;
     unsigned char foo[64];
     int i;
 
     memset(foo, 0x36, 64);
     for (i = 0; i < len && i < 64; i++)
 	foo[i] ^= key[i];
-    MD5Init(s1);
+    MD5Init(&keys[0]);
-    MD5Update(s1, foo, 64);
+    MD5Update(&keys[0], foo, 64);
 
     memset(foo, 0x5C, 64);
     for (i = 0; i < len && i < 64; i++)
 	foo[i] ^= key[i];
-    MD5Init(s2);
+    MD5Init(&keys[0]);
-    MD5Update(s2, foo, 64);
+    MD5Update(&keys[0], foo, 64);
 
     memset(foo, 0, 64);		       /* burn the evidence */
 }
 
-static void md5_cskey(unsigned char *key)
+static void md5_key(void *handle, unsigned char *key)
 {
-    md5_key(&md5_cs_mac_s1, &md5_cs_mac_s2, key, 16);
+    md5_key_internal(handle, key, 16);
 }
 
-static void md5_sckey(unsigned char *key)
+static void md5_do_hmac(void *handle, unsigned char *blk, int len,
-{
+			unsigned long seq, unsigned char *hmac)
-    md5_key(&md5_sc_mac_s1, &md5_sc_mac_s2, key, 16);
-}
-
-static void md5_do_hmac(struct MD5Context *s1, struct MD5Context *s2,
-			unsigned char *blk, int len, unsigned long seq,
-			unsigned char *hmac)
 {
+    struct MD5Context *keys = (struct MD5Context *)handle;
     struct MD5Context s;
     unsigned char intermediate[16];
 
@@ -254,31 +256,32 @@ static void md5_do_hmac(struct MD5Context *s1, struct MD5Context *s2,
     intermediate[2] = (unsigned char) ((seq >> 8) & 0xFF);
     intermediate[3] = (unsigned char) ((seq) & 0xFF);
 
-    s = *s1;			       /* structure copy */
+    s = keys[0];		       /* structure copy */
     MD5Update(&s, intermediate, 4);
     MD5Update(&s, blk, len);
     MD5Final(intermediate, &s);
-    s = *s2;			       /* structure copy */
+    s = keys[1];		       /* structure copy */
     MD5Update(&s, intermediate, 16);
     MD5Final(hmac, &s);
 }
 
-static void md5_generate(unsigned char *blk, int len, unsigned long seq)
+static void md5_generate(void *handle, unsigned char *blk, int len,
+			 unsigned long seq)
 {
-    md5_do_hmac(&md5_cs_mac_s1, &md5_cs_mac_s2, blk, len, seq, blk + len);
+    md5_do_hmac(handle, blk, len, seq, blk + len);
 }
 
-static int md5_verify(unsigned char *blk, int len, unsigned long seq)
+static int md5_verify(void *handle, unsigned char *blk, int len,
+		      unsigned long seq)
 {
     unsigned char correct[16];
-    md5_do_hmac(&md5_sc_mac_s1, &md5_sc_mac_s2, blk, len, seq, correct);
+    md5_do_hmac(handle, blk, len, seq, correct);
     return !memcmp(correct, blk + len, 16);
 }
 
 const struct ssh_mac ssh_md5 = {
-    md5_cskey, md5_sckey,
+    md5_make_context, md5_free_context, md5_key,
-    md5_generate,
+    md5_generate, md5_verify,
-    md5_verify,
     "hmac-md5",
     16
 };

sshsha.c

@@ -193,54 +193,51 @@ void SHA_Simple(void *p, int len, unsigned char *output)
  * HMAC wrapper on it.
  */
 
-static SHA_State sha1_cs_mac_s1, sha1_cs_mac_s2;
+static void *sha1_make_context(void)
-static SHA_State sha1_sc_mac_s1, sha1_sc_mac_s2;
-
-static void sha1_key(SHA_State * s1, SHA_State * s2,
-		     unsigned char *key, int len)
 {
+    return smalloc(2*sizeof(SHA_State));
+}
+
+static void sha1_free_context(void *handle)
+{
+    sfree(handle);
+}
+
+static void sha1_key_internal(void *handle, unsigned char *key, int len)
+{
+    SHA_State *keys = (SHA_State *)handle;
     unsigned char foo[64];
     int i;
 
     memset(foo, 0x36, 64);
     for (i = 0; i < len && i < 64; i++)
 	foo[i] ^= key[i];
-    SHA_Init(s1);
+    SHA_Init(&keys[0]);
-    SHA_Bytes(s1, foo, 64);
+    SHA_Bytes(&keys[0], foo, 64);
 
     memset(foo, 0x5C, 64);
     for (i = 0; i < len && i < 64; i++)
 	foo[i] ^= key[i];
-    SHA_Init(s2);
+    SHA_Init(&keys[1]);
-    SHA_Bytes(s2, foo, 64);
+    SHA_Bytes(&keys[1], foo, 64);
 
     memset(foo, 0, 64);		       /* burn the evidence */
 }
 
-static void sha1_cskey(unsigned char *key)
+static void sha1_key(void *handle, unsigned char *key)
 {
-    sha1_key(&sha1_cs_mac_s1, &sha1_cs_mac_s2, key, 20);
+    sha1_key_internal(handle, key, 20);
 }
 
-static void sha1_sckey(unsigned char *key)
+static void sha1_key_buggy(void *handle, unsigned char *key)
 {
-    sha1_key(&sha1_sc_mac_s1, &sha1_sc_mac_s2, key, 20);
+    sha1_key_internal(handle, key, 16);
 }
 
-static void sha1_cskey_buggy(unsigned char *key)
+static void sha1_do_hmac(void *handle, unsigned char *blk, int len,
-{
+			 unsigned long seq, unsigned char *hmac)
-    sha1_key(&sha1_cs_mac_s1, &sha1_cs_mac_s2, key, 16);
-}
-
-static void sha1_sckey_buggy(unsigned char *key)
-{
-    sha1_key(&sha1_sc_mac_s1, &sha1_sc_mac_s2, key, 16);
-}
-
-static void sha1_do_hmac(SHA_State * s1, SHA_State * s2,
-			 unsigned char *blk, int len, unsigned long seq,
-			 unsigned char *hmac)
 {
+    SHA_State *keys = (SHA_State *)handle;
     SHA_State s;
     unsigned char intermediate[20];
 
@@ -249,53 +246,52 @@ static void sha1_do_hmac(SHA_State * s1, SHA_State * s2,
     intermediate[2] = (unsigned char) ((seq >> 8) & 0xFF);
     intermediate[3] = (unsigned char) ((seq) & 0xFF);
 
-    s = *s1;			       /* structure copy */
+    s = keys[0];		       /* structure copy */
     SHA_Bytes(&s, intermediate, 4);
     SHA_Bytes(&s, blk, len);
     SHA_Final(&s, intermediate);
-    s = *s2;			       /* structure copy */
+    s = keys[1];		       /* structure copy */
     SHA_Bytes(&s, intermediate, 20);
     SHA_Final(&s, hmac);
 }
 
-static void sha1_generate(unsigned char *blk, int len, unsigned long seq)
+static void sha1_generate(void *handle, unsigned char *blk, int len,
+			  unsigned long seq)
 {
-    sha1_do_hmac(&sha1_cs_mac_s1, &sha1_cs_mac_s2, blk, len, seq,
+    sha1_do_hmac(handle, blk, len, seq, blk + len);
-		 blk + len);
 }
 
-static int sha1_verify(unsigned char *blk, int len, unsigned long seq)
+static int sha1_verify(void *handle, unsigned char *blk, int len,
+		       unsigned long seq)
 {
     unsigned char correct[20];
-    sha1_do_hmac(&sha1_sc_mac_s1, &sha1_sc_mac_s2, blk, len, seq, correct);
+    sha1_do_hmac(handle, blk, len, seq, correct);
     return !memcmp(correct, blk + len, 20);
 }
 
 void hmac_sha1_simple(void *key, int keylen, void *data, int datalen,
 		      unsigned char *output) {
-    SHA_State s1, s2;
+    SHA_State states[2];
     unsigned char intermediate[20];
 
-    sha1_key(&s1, &s2, key, keylen);
+    sha1_key_internal(states, key, keylen);
-    SHA_Bytes(&s1, data, datalen);
+    SHA_Bytes(&states[0], data, datalen);
-    SHA_Final(&s1, intermediate);
+    SHA_Final(&states[0], intermediate);
 
-    SHA_Bytes(&s2, intermediate, 20);
+    SHA_Bytes(&states[1], intermediate, 20);
-    SHA_Final(&s2, output);
+    SHA_Final(&states[1], output);
 }
 
 const struct ssh_mac ssh_sha1 = {
-    sha1_cskey, sha1_sckey,
+    sha1_make_context, sha1_free_context, sha1_key,
-    sha1_generate,
+    sha1_generate, sha1_verify,
-    sha1_verify,
     "hmac-sha1",
     20
 };
 
 const struct ssh_mac ssh_sha1_buggy = {
-    sha1_cskey_buggy, sha1_sckey_buggy,
+    sha1_make_context, sha1_free_context, sha1_key_buggy,
-    sha1_generate,
+    sha1_generate, sha1_verify,
-    sha1_verify,
     "hmac-sha1",
     20
 };