1 files changed, 150 insertions, 0 deletions
diff --git a/src/fuzzer/mode_padding.cpp b/src/fuzzer/mode_padding.cpp
new file mode 100644
index 000000000..05cb1a8f6
--- /dev/null
+++ b/src/fuzzer/mode_padding.cpp
@@ -0,0 +1,150 @@
+/*
+* (C) 2018 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include "fuzzers.h"
+#include <botan/mode_pad.h>
+#include <botan/internal/tls_cbc.h>
+
+size_t ref_pkcs7_unpad(const uint8_t in[], size_t len)
+   {
+   if(len <= 2)
+      return len;
+
+   const size_t padding_length = in[len-1];
+
+   if(padding_length == 0 || padding_length > len)
+      return len;
+
+   const size_t padding_start = len - padding_length;
+
+   for(size_t i = padding_start; i != len; ++i)
+      {
+      if(in[i] != padding_length)
+         return len;
+      }
+
+   return len - padding_length;
+   }
+
+size_t ref_x923_unpad(const uint8_t in[], size_t len)
+   {
+   if(len <= 2)
+      return len;
+
+   const size_t padding_length = in[len-1];
+
+   if(padding_length == 0 || padding_length > len)
+      return len;
+   const size_t padding_start = len - padding_length;
+
+   for(size_t i = padding_start; i != len - 1; ++i)
+      {
+      if(in[i] != 0)
+         {
+         return len;
+         }
+      }
+
+   return len - padding_length;
+   }
+
+size_t ref_oneandzero_unpad(const uint8_t in[], size_t len)
+   {
+   if(len <= 2)
+      return len;
+
+   size_t idx = len - 1;
+
+   while(idx >= 0)
+      {
+      if(in[idx] == 0)
+         {
+         idx -= 1;
+         continue;
+         }
+      else if(in[idx] == 0x80)
+         {
+         return idx;
+         }
+      else
+         return len;
+      }
+
+   return len;
+   }
+
+size_t ref_esp_unpad(const uint8_t in[], size_t len)
+   {
+   if(len <= 2)
+      return len;
+
+   const size_t padding_bytes = in[len - 1];
+
+   if(padding_bytes == 0 || padding_bytes > len)
+      {
+      return len;
+      }
+
+   const size_t padding_start = len - padding_bytes;
+   for(size_t i = padding_start; i != len; ++i)
+      {
+      if(in[i] != (i - padding_start + 1))
+         {
+         return len;
+         }
+      }
+
+   return len - padding_bytes;
+   }
+
+uint16_t ref_tls_cbc_unpad(const uint8_t in[], size_t len)
+   {
+   if(len == 0)
+      return 0;
+
+   const size_t padding_length = in[(len-1)];
+
+   if(padding_length >= len)
+      return 0;
+
+   /*
+   * TLS v1.0 and up require all the padding bytes be the same value
+   * and allows up to 255 bytes.
+   */
+   for(size_t i = 0; i != 1 + padding_length; ++i)
+      {
+      if(in[(len-i-1)] != padding_length)
+         return 0;
+      }
+   return padding_length + 1;
+   }
+
+void fuzz(const uint8_t in[], size_t len)
+   {
+   Botan::PKCS7_Padding pkcs7;
+   const size_t ct_pkcs7 = pkcs7.unpad(in, len);
+   const size_t ref_pkcs7 = ref_pkcs7_unpad(in, len);
+   FUZZER_ASSERT_EQUAL(ct_pkcs7, ref_pkcs7);
+
+   Botan::ANSI_X923_Padding x923;
+   const size_t ct_x923 = x923.unpad(in, len);
+   const size_t ref_x923 = ref_x923_unpad(in, len);
+   FUZZER_ASSERT_EQUAL(ct_x923, ref_x923);
+
+   Botan::OneAndZeros_Padding oneandzero;
+   const size_t ct_oneandzero = oneandzero.unpad(in, len);
+   const size_t ref_oneandzero = ref_oneandzero_unpad(in, len);
+   FUZZER_ASSERT_EQUAL(ct_oneandzero, ref_oneandzero);
+
+   Botan::ESP_Padding esp;
+   const size_t ct_esp = esp.unpad(in, len);
+   const size_t ref_esp = ref_esp_unpad(in, len);
+   FUZZER_ASSERT_EQUAL(ct_esp, ref_esp);
+
+   const uint16_t ct_cbc = Botan::TLS::check_tls_cbc_padding(in, len);
+   const uint16_t ref_cbc = ref_tls_cbc_unpad(in, len);
+   FUZZER_ASSERT_EQUAL(ct_cbc, ref_cbc);
+   }