Reimplement DSA parsing logic with crypto/asn1.

Functions which lose object reuse and need auditing:
- d2i_DSA_SIG
- d2i_DSAPublicKey
- d2i_DSAPrivateKey
- d2i_DSAparams

BUG=499653

Change-Id: I1cc2ae10e1e77eb57da3a858ac8734a95715ce4b
Reviewed-on: https://boringssl-review.googlesource.com/7022
Reviewed-by: Adam Langley <agl@google.com>

3 files changed, 269 insertions, 55 deletions

diff --git a/crypto/dsa/dsa.c b/crypto/dsa/dsa.c
index 2a9524a3..3b269d4f 100644
--- a/crypto/dsa/dsa.c
+++ b/crypto/dsa/dsa.c
@@ -392,6 +392,21 @@ err:
   return ok;
 }
 
+DSA *DSAparams_dup(const DSA *dsa) {
+  DSA *ret = DSA_new();
+  if (ret == NULL) {
+    return NULL;
+  }
+  ret->p = BN_dup(dsa->p);
+  ret->q = BN_dup(dsa->q);
+  ret->g = BN_dup(dsa->g);
+  if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
+    DSA_free(ret);
+    return NULL;
+  }
+  return ret;
+}
+
 int DSA_generate_key(DSA *dsa) {
   int ok = 0;
   BN_CTX *ctx = NULL;
diff --git a/crypto/dsa/dsa_asn1.c b/crypto/dsa/dsa_asn1.c
index 4df561d6..d7b826cc 100644
--- a/crypto/dsa/dsa_asn1.c
+++ b/crypto/dsa/dsa_asn1.c
@@ -54,87 +54,283 @@
 
 #include <openssl/dsa.h>
 
-#include <string.h>
+#include <assert.h>
 
-#include <openssl/asn1.h>
-#include <openssl/asn1t.h>
+#include <openssl/bn.h>
+#include <openssl/bytestring.h>
 #include <openssl/err.h>
 #include <openssl/mem.h>
 
 #include "internal.h"
+#include "../bytestring/internal.h"
 
 
-static int dsa_sig_cb(int operation, ASN1_VALUE **pval, const ASN1_ITEM *it,
-                      void *exarg) {
-  if (operation != ASN1_OP_NEW_PRE) {
-    return 1;
+static int parse_integer(CBS *cbs, BIGNUM **out) {
+  assert(*out == NULL);
+  *out = BN_new();
+  if (*out == NULL) {
+    return 0;
+  }
+  return BN_parse_asn1_unsigned(cbs, *out);
+}
+
+static int marshal_integer(CBB *cbb, BIGNUM *bn) {
+  if (bn == NULL) {
+    /* A DSA object may be missing some components. */
+    OPENSSL_PUT_ERROR(DSA, ERR_R_PASSED_NULL_PARAMETER);
+    return 0;
+  }
+  return BN_marshal_asn1(cbb, bn);
+}
+
+DSA_SIG *DSA_SIG_parse(CBS *cbs) {
+  DSA_SIG *ret = DSA_SIG_new();
+  if (ret == NULL) {
+    return NULL;
+  }
+  CBS child;
+  if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
+      !parse_integer(&child, &ret->r) ||
+      !parse_integer(&child, &ret->s) ||
+      CBS_len(&child) != 0) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
+    DSA_SIG_free(ret);
+    return NULL;
   }
+  return ret;
+}
 
-  DSA_SIG *sig;
-  sig = OPENSSL_malloc(sizeof(DSA_SIG));
-  if (!sig) {
-    OPENSSL_PUT_ERROR(DSA, ERR_R_MALLOC_FAILURE);
+int DSA_SIG_marshal(CBB *cbb, const DSA_SIG *sig) {
+  CBB child;
+  if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
+      !marshal_integer(&child, sig->r) ||
+      !marshal_integer(&child, sig->s) ||
+      !CBB_flush(cbb)) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
     return 0;
   }
+  return 1;
+}
+
+DSA *DSA_parse_public_key(CBS *cbs) {
+  DSA *ret = DSA_new();
+  if (ret == NULL) {
+    return NULL;
+  }
+  CBS child;
+  if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
+      !parse_integer(&child, &ret->pub_key) ||
+      !parse_integer(&child, &ret->p) ||
+      !parse_integer(&child, &ret->q) ||
+      !parse_integer(&child, &ret->g) ||
+      CBS_len(&child) != 0) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
+    DSA_free(ret);
+    return NULL;
+  }
+  return ret;
+}
 
-  memset(sig, 0, sizeof(DSA_SIG));
-  *pval = (ASN1_VALUE *)sig;
-  return 2;
+int DSA_marshal_public_key(CBB *cbb, const DSA *dsa) {
+  CBB child;
+  if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
+      !marshal_integer(&child, dsa->pub_key) ||
+      !marshal_integer(&child, dsa->p) ||
+      !marshal_integer(&child, dsa->q) ||
+      !marshal_integer(&child, dsa->g) ||
+      !CBB_flush(cbb)) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
+    return 0;
+  }
+  return 1;
 }
 
-ASN1_SEQUENCE_cb(DSA_SIG, dsa_sig_cb) = {
-    ASN1_SIMPLE(DSA_SIG, r, CBIGNUM),
-    ASN1_SIMPLE(DSA_SIG, s, CBIGNUM)} ASN1_SEQUENCE_END_cb(DSA_SIG, DSA_SIG);
+DSA *DSA_parse_parameters(CBS *cbs) {
+  DSA *ret = DSA_new();
+  if (ret == NULL) {
+    return NULL;
+  }
+  CBS child;
+  if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
+      !parse_integer(&child, &ret->p) ||
+      !parse_integer(&child, &ret->q) ||
+      !parse_integer(&child, &ret->g) ||
+      CBS_len(&child) != 0) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
+    DSA_free(ret);
+    return NULL;
+  }
+  return ret;
+}
 
-IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(DSA_SIG, DSA_SIG, DSA_SIG);
+int DSA_marshal_parameters(CBB *cbb, const DSA *dsa) {
+  CBB child;
+  if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
+      !marshal_integer(&child, dsa->p) ||
+      !marshal_integer(&child, dsa->q) ||
+      !marshal_integer(&child, dsa->g) ||
+      !CBB_flush(cbb)) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
+    return 0;
+  }
+  return 1;
+}
 
+DSA *DSA_parse_private_key(CBS *cbs) {
+  DSA *ret = DSA_new();
+  if (ret == NULL) {
+    return NULL;
+  }
 
-static int dsa_cb(int operation, ASN1_VALUE **pval, const ASN1_ITEM *it,
-                  void *exarg) {
-  switch (operation) {
-    case ASN1_OP_NEW_PRE:
-      *pval = (ASN1_VALUE *)DSA_new();
-      if (*pval) {
-        return 2;
-      }
-      return 0;
+  CBS child;
+  uint64_t version;
+  if (!CBS_get_asn1(cbs, &child, CBS_ASN1_SEQUENCE) ||
+      !CBS_get_asn1_uint64(&child, &version)) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
+    goto err;
+  }
 
-    case ASN1_OP_FREE_PRE:
-      DSA_free((DSA *)*pval);
-      *pval = NULL;
-      return 2;
+  if (version != 0) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_BAD_VERSION);
+    goto err;
+  }
 
-    default:
-      return 1;
+  if (!parse_integer(&child, &ret->p) ||
+      !parse_integer(&child, &ret->q) ||
+      !parse_integer(&child, &ret->g) ||
+      !parse_integer(&child, &ret->pub_key) ||
+      !parse_integer(&child, &ret->priv_key) ||
+      CBS_len(&child) != 0) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_DECODE_ERROR);
+    goto err;
   }
+  return ret;
+
+err:
+  DSA_free(ret);
+  return NULL;
 }
 
-ASN1_SEQUENCE_cb(DSAPrivateKey, dsa_cb) = {
-    ASN1_SIMPLE(DSA, version, LONG),
-    ASN1_SIMPLE(DSA, p, BIGNUM),
-    ASN1_SIMPLE(DSA, q, BIGNUM),
-    ASN1_SIMPLE(DSA, g, BIGNUM),
-    ASN1_SIMPLE(DSA, pub_key, BIGNUM),
-    ASN1_SIMPLE(DSA, priv_key, BIGNUM)} ASN1_SEQUENCE_END_cb(DSA,
-                                                             DSAPrivateKey);
+int DSA_marshal_private_key(CBB *cbb, const DSA *dsa) {
+  CBB child;
+  if (!CBB_add_asn1(cbb, &child, CBS_ASN1_SEQUENCE) ||
+      !CBB_add_asn1_uint64(&child, 0 /* version */) ||
+      !marshal_integer(&child, dsa->p) ||
+      !marshal_integer(&child, dsa->q) ||
+      !marshal_integer(&child, dsa->g) ||
+      !marshal_integer(&child, dsa->pub_key) ||
+      !marshal_integer(&child, dsa->priv_key) ||
+      !CBB_flush(cbb)) {
+    OPENSSL_PUT_ERROR(DSA, DSA_R_ENCODE_ERROR);
+    return 0;
+  }
+  return 1;
+}
 
-IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(DSA, DSAPrivateKey, DSAPrivateKey);
+DSA_SIG *d2i_DSA_SIG(DSA_SIG **out_sig, const uint8_t **inp, long len) {
+  if (len < 0) {
+    return NULL;
+  }
+  CBS cbs;
+  CBS_init(&cbs, *inp, (size_t)len);
+  DSA_SIG *ret = DSA_SIG_parse(&cbs);
+  if (ret == NULL) {
+    return NULL;
+  }
+  if (out_sig != NULL) {
+    DSA_SIG_free(*out_sig);
+    *out_sig = ret;
+  }
+  *inp = CBS_data(&cbs);
+  return ret;
+}
 
-ASN1_SEQUENCE_cb(DSAparams, dsa_cb) = {
-    ASN1_SIMPLE(DSA, p, BIGNUM), ASN1_SIMPLE(DSA, q, BIGNUM),
-    ASN1_SIMPLE(DSA, g, BIGNUM), } ASN1_SEQUENCE_END_cb(DSA, DSAparams);
+int i2d_DSA_SIG(const DSA_SIG *in, uint8_t **outp) {
+  CBB cbb;
+  if (!CBB_init(&cbb, 0) ||
+      !DSA_SIG_marshal(&cbb, in)) {
+    return -1;
+  }
+  return CBB_finish_i2d(&cbb, outp);
+}
 
-IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(DSA, DSAparams, DSAparams);
+DSA *d2i_DSAPublicKey(DSA **out, const uint8_t **inp, long len) {
+  if (len < 0) {
+    return NULL;
+  }
+  CBS cbs;
+  CBS_init(&cbs, *inp, (size_t)len);
+  DSA *ret = DSA_parse_public_key(&cbs);
+  if (ret == NULL) {
+    return NULL;
+  }
+  if (out != NULL) {
+    DSA_free(*out);
+    *out = ret;
+  }
+  *inp = CBS_data(&cbs);
+  return ret;
+}
 
-ASN1_SEQUENCE_cb(DSAPublicKey, dsa_cb) = {
-	ASN1_SIMPLE(DSA, pub_key, BIGNUM),
-	ASN1_SIMPLE(DSA, p, BIGNUM),
-	ASN1_SIMPLE(DSA, q, BIGNUM),
-	ASN1_SIMPLE(DSA, g, BIGNUM)
-} ASN1_SEQUENCE_END_cb(DSA, DSAPublicKey);
+int i2d_DSAPublicKey(const DSA *in, uint8_t **outp) {
+  CBB cbb;
+  if (!CBB_init(&cbb, 0) ||
+      !DSA_marshal_public_key(&cbb, in)) {
+    return -1;
+  }
+  return CBB_finish_i2d(&cbb, outp);
+}
 
-IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(DSA, DSAPublicKey, DSAPublicKey);
+DSA *d2i_DSAPrivateKey(DSA **out, const uint8_t **inp, long len) {
+  if (len < 0) {
+    return NULL;
+  }
+  CBS cbs;
+  CBS_init(&cbs, *inp, (size_t)len);
+  DSA *ret = DSA_parse_private_key(&cbs);
+  if (ret == NULL) {
+    return NULL;
+  }
+  if (out != NULL) {
+    DSA_free(*out);
+    *out = ret;
+  }
+  *inp = CBS_data(&cbs);
+  return ret;
+}
+
+int i2d_DSAPrivateKey(const DSA *in, uint8_t **outp) {
+  CBB cbb;
+  if (!CBB_init(&cbb, 0) ||
+      !DSA_marshal_private_key(&cbb, in)) {
+    return -1;
+  }
+  return CBB_finish_i2d(&cbb, outp);
+}
 
-DSA *DSAparams_dup(const DSA *dsa) {
-  return ASN1_item_dup(ASN1_ITEM_rptr(DSAparams), (DSA*) dsa);
+DSA *d2i_DSAparams(DSA **out, const uint8_t **inp, long len) {
+  if (len < 0) {
+    return NULL;
+  }
+  CBS cbs;
+  CBS_init(&cbs, *inp, (size_t)len);
+  DSA *ret = DSA_parse_parameters(&cbs);
+  if (ret == NULL) {
+    return NULL;
+  }
+  if (out != NULL) {
+    DSA_free(*out);
+    *out = ret;
+  }
+  *inp = CBS_data(&cbs);
+  return ret;
+}
+
+int i2d_DSAparams(const DSA *in, uint8_t **outp) {
+  CBB cbb;
+  if (!CBB_init(&cbb, 0) ||
+      !DSA_marshal_parameters(&cbb, in)) {
+    return -1;
+  }
+  return CBB_finish_i2d(&cbb, outp);
 }
diff --git a/crypto/err/dsa.errordata b/crypto/err/dsa.errordata
index 3c5764a1..6f4bc138 100644
--- a/crypto/err/dsa.errordata
+++ b/crypto/err/dsa.errordata
@@ -1,4 +1,7 @@
 DSA,100,BAD_Q_VALUE
+DSA,104,BAD_VERSION
+DSA,105,DECODE_ERROR
+DSA,106,ENCODE_ERROR
 DSA,101,MISSING_PARAMETERS
 DSA,102,MODULUS_TOO_LARGE
 DSA,103,NEED_NEW_SETUP_VALUES