Fixed possible buffer overflow in PKSC#1 message decoding.

[crypto.git] / lib / silccrypt / silcpkcs1.c

diff --git a/lib/silccrypt/silcpkcs1.c b/lib/silccrypt/silcpkcs1.c
index 398411d5bd4f4875f69985a12527f177015323e2..653a4d891fbd8d42aa014ff3763b83e14ccd6553 100644 (file)
--- a/lib/silccrypt/silcpkcs1.c
+++ b/lib/silccrypt/silcpkcs1.c
@@ -107,7 +107,7 @@ SilcBool silc_pkcs1_decode(SilcPkcs1BlockType bt,
                           SilcUInt32 dest_data_size,
                           SilcUInt32 *dest_len)
 {
-  int i = 0;
+  SilcUInt32 i = 0;
 
   SILC_LOG_DEBUG(("PKCS#1 decoding, bt %d", bt));
 
@@ -140,12 +140,20 @@ SilcBool silc_pkcs1_decode(SilcPkcs1BlockType bt,
   }
 
   /* Sanity checks */
+  if (i >= data_len) {
+    SILC_LOG_DEBUG(("Malformed block, too short message"));
+    return FALSE;
+  }
+  if (i < SILC_PKCS1_MIN_PADDING) {
+    SILC_LOG_DEBUG(("Malformed block, too short padding"));
+    return FALSE;
+  }
   if (data[i++] != 0x00) {
     SILC_LOG_DEBUG(("Malformed block"));
     return FALSE;
   }
-  if (i - 1 < SILC_PKCS1_MIN_PADDING) {
-    SILC_LOG_DEBUG(("Malformed block"));
+  if (i >= data_len) {
+    SILC_LOG_DEBUG(("Malformed block, too short message"));
     return FALSE;
   }
   if (dest_data_size < data_len - i) {
@@ -338,6 +346,7 @@ SILC_PKCS_ALG_PUBLIC_KEY_FREE(silc_pkcs1_public_key_free)
 
   silc_mp_uninit(&key->n);
   silc_mp_uninit(&key->e);
+  silc_hash_free(key->hash);
   silc_free(key);
 }
 
@@ -457,6 +466,7 @@ SILC_PKCS_ALG_PRIVATE_KEY_FREE(silc_pkcs1_private_key_free)
   silc_mp_uninit(&key->qP);
   silc_mp_uninit(&key->p);
   silc_mp_uninit(&key->q);
+  silc_hash_free(key->hash);
   silc_free(key);
 }
 
@@ -501,8 +511,8 @@ SILC_PKCS_ALG_ENCRYPT(silc_pkcs1_encrypt)
   encrypt_cb(TRUE, padded, len, context);
 
   memset(padded, 0, sizeof(padded));
-  silc_mp_suninit(stack, &mp_tmp);
-  silc_mp_suninit(stack, &mp_dst);
+  silc_mp_uninit(&mp_tmp);
+  silc_mp_uninit(&mp_dst);
   silc_stack_free(stack);
 
   return NULL;
@@ -541,8 +551,8 @@ SILC_PKCS_ALG_DECRYPT(silc_pkcs1_decrypt)
                         unpadded, sizeof(unpadded), &dst_len)) {
     memset(padded, 0, padded_len);
     silc_free(padded);
-    silc_mp_suninit(stack, &mp_tmp);
-    silc_mp_suninit(stack, &mp_dst);
+    silc_mp_uninit(&mp_tmp);
+    silc_mp_uninit(&mp_dst);
     decrypt_cb(FALSE, NULL, 0, context);
     return NULL;
   }
@@ -553,8 +563,8 @@ SILC_PKCS_ALG_DECRYPT(silc_pkcs1_decrypt)
   memset(padded, 0, padded_len);
   memset(unpadded, 0, sizeof(unpadded));
   silc_free(padded);
-  silc_mp_suninit(stack, &mp_tmp);
-  silc_mp_suninit(stack, &mp_dst);
+  silc_mp_uninit(&mp_tmp);
+  silc_mp_uninit(&mp_dst);
   silc_stack_free(stack);
 
   return NULL;
@@ -598,6 +608,8 @@ SILC_PKCS_ALG_SIGN(silc_pkcs1_sign)
 
   /* Compute hash */
   if (compute_hash) {
+    if (!hash)
+      hash = key->hash;
     silc_hash_make(hash, src, src_len, hashr);
     src = hashr;
     src_len = silc_hash_len(hash);
@@ -648,8 +660,8 @@ SILC_PKCS_ALG_SIGN(silc_pkcs1_sign)
   memset(padded, 0, sizeof(padded));
   if (compute_hash)
     memset(hashr, 0, sizeof(hashr));
-  silc_mp_suninit(stack, &mp_tmp);
-  silc_mp_suninit(stack, &mp_dst);
+  silc_mp_uninit(&mp_tmp);
+  silc_mp_uninit(&mp_dst);
   silc_asn1_free(asn1);
   silc_stack_free(stack);
 
@@ -702,33 +714,35 @@ SILC_PKCS_ALG_VERIFY(silc_pkcs1_verify)
   silc_buffer_set(&di, unpadded, len);
 
   /* If hash isn't given, allocate the one given in digest info */
-  if (!hash) {
-    has_null = FALSE;
+  if (compute_hash) {
+    if (!hash) {
+      has_null = FALSE;
 
-    /* Decode digest info */
-    if (!silc_asn1_decode(asn1, &di,
-                         SILC_ASN1_OPTS(SILC_ASN1_ACCUMUL),
-                         SILC_ASN1_SEQUENCE,
+      /* Decode digest info */
+      if (!silc_asn1_decode(asn1, &di,
+                           SILC_ASN1_OPTS(SILC_ASN1_ACCUMUL),
                            SILC_ASN1_SEQUENCE,
-                             SILC_ASN1_OID(&oid),
-                             SILC_ASN1_NULL_T(SILC_ASN1_OPTIONAL,
-                                              SILC_ASN1_TAG_NULL, &has_null),
-                           SILC_ASN1_END,
-                         SILC_ASN1_END, SILC_ASN1_END))
-      goto err;
-
-    if (!silc_hash_alloc_by_oid(oid, &ihash)) {
-      SILC_LOG_DEBUG(("Unknown OID %s", oid));
-      goto err;
+                             SILC_ASN1_SEQUENCE,
+                               SILC_ASN1_OID(&oid),
+                               SILC_ASN1_NULL_T(SILC_ASN1_OPTIONAL,
+                                                SILC_ASN1_TAG_NULL, &has_null),
+                             SILC_ASN1_END,
+                           SILC_ASN1_END, SILC_ASN1_END))
+       goto err;
+
+      if (!silc_hash_alloc_by_oid(oid, &ihash)) {
+       SILC_LOG_DEBUG(("Unknown OID %s", oid));
+       goto err;
+      }
+      hash = ihash;
     }
-    hash = ihash;
-  }
 
-  /* Hash the data */
-  silc_hash_make(hash, data, data_len, hashr);
-  data = hashr;
-  data_len = silc_hash_len(hash);
-  oid = (char *)silc_hash_get_oid(hash);
+    /* Hash the data */
+    silc_hash_make(hash, data, data_len, hashr);
+    data = hashr;
+    data_len = silc_hash_len(hash);
+    oid = (char *)silc_hash_get_oid(hash);
+  }
 
   /* Encode digest info for comparison */
   memset(&ldi, 0, sizeof(ldi));
@@ -760,9 +774,9 @@ SILC_PKCS_ALG_VERIFY(silc_pkcs1_verify)
   memset(verify, 0, verify_len);
   memset(unpadded, 0, sizeof(unpadded));
   silc_free(verify);
-  silc_mp_suninit(stack, &mp_tmp2);
-  silc_mp_suninit(stack, &mp_dst);
-  if (hash)
+  silc_mp_uninit(&mp_tmp2);
+  silc_mp_uninit(&mp_dst);
+  if (compute_hash)
     memset(hashr, 0, sizeof(hashr));
   if (ihash)
     silc_hash_free(ihash);
@@ -774,8 +788,8 @@ SILC_PKCS_ALG_VERIFY(silc_pkcs1_verify)
  err:
   memset(verify, 0, verify_len);
   silc_free(verify);
-  silc_mp_suninit(stack, &mp_tmp2);
-  silc_mp_suninit(stack, &mp_dst);
+  silc_mp_uninit(&mp_tmp2);
+  silc_mp_uninit(&mp_dst);
   if (ihash)
     silc_hash_free(ihash);
   silc_asn1_free(asn1);
@@ -805,6 +819,8 @@ SILC_PKCS_ALG_SIGN(silc_pkcs1_sign_no_oid)
 
   /* Compute hash if requested */
   if (compute_hash) {
+    if (!hash)
+      hash = key->hash;
     silc_hash_make(hash, src, src_len, hashr);
     src = hashr;
     src_len = silc_hash_len(hash);
@@ -837,8 +853,8 @@ SILC_PKCS_ALG_SIGN(silc_pkcs1_sign_no_oid)
   memset(padded, 0, sizeof(padded));
   if (compute_hash)
     memset(hashr, 0, sizeof(hashr));
-  silc_mp_suninit(stack, &mp_tmp);
-  silc_mp_suninit(stack, &mp_dst);
+  silc_mp_uninit(&mp_tmp);
+  silc_mp_uninit(&mp_dst);
   silc_stack_free(stack);
 
   return NULL;
@@ -877,15 +893,17 @@ SILC_PKCS_ALG_VERIFY(silc_pkcs1_verify_no_oid)
                         unpadded, sizeof(unpadded), &len)) {
     memset(verify, 0, verify_len);
     silc_free(verify);
-    silc_mp_suninit(stack, &mp_tmp2);
-    silc_mp_suninit(stack, &mp_dst);
+    silc_mp_uninit(&mp_tmp2);
+    silc_mp_uninit(&mp_dst);
     silc_stack_free(stack);
     verify_cb(FALSE, context);
     return NULL;
   }
 
   /* Hash data if requested */
-  if (hash) {
+  if (compute_hash) {
+    if (!hash)
+      hash = key->hash;
     silc_hash_make(hash, data, data_len, hashr);
     data = hashr;
     data_len = silc_hash_len(hash);
@@ -900,11 +918,11 @@ SILC_PKCS_ALG_VERIFY(silc_pkcs1_verify_no_oid)
 
   memset(verify, 0, verify_len);
   memset(unpadded, 0, sizeof(unpadded));
-  if (hash)
+  if (compute_hash)
     memset(hashr, 0, sizeof(hashr));
   silc_free(verify);
-  silc_mp_suninit(stack, &mp_tmp2);
-  silc_mp_suninit(stack, &mp_dst);
+  silc_mp_uninit(&mp_tmp2);
+  silc_mp_uninit(&mp_dst);
   silc_stack_free(stack);
 
   return NULL;