promote filesize to a hashstring

It is a very simple hashstring, which is why it isn't contributing to
the usability of a list of them, but it is also trivial to check and
calculate, so it doesn't hurt checking it either as it can combined even
with the simplest other hashes greatly complicate attacks on them as you
suddenly need a same-size hash collision, which is usually a lot harder
to achieve.

apt-pkg/contrib/hashes.cc

@@ -29,7 +29,7 @@
 
 const char * HashString::_SupportedHashes[] =
 {
-   "SHA512", "SHA256", "SHA1", "MD5Sum", NULL
+   "SHA512", "SHA256", "SHA1", "MD5Sum", "Checksum-FileSize", NULL
 };
 
 HashString::HashString()
@@ -111,6 +111,8 @@ std::string HashString::GetHashForFile(std::string filename) const      /*{{{*/
       SHA512.AddFD(Fd);
       fileHash = (std::string)SHA512.Result();
    }
+   else if (strcasecmp(Type.c_str(), "Checksum-FileSize") == 0)
+      strprintf(fileHash, "%llu", Fd.FileSize());
    Fd.Close();
 
    return fileHash;
@@ -147,7 +149,13 @@ bool HashStringList::usable() const					/*{{{*/
       return false;
    std::string const forcedType = _config->Find("Acquire::ForceHash", "");
    if (forcedType.empty() == true)
-      return true;
+   {
+      // FileSize alone isn't usable
+      for (std::vector<HashString>::const_iterator hs = list.begin(); hs != list.end(); ++hs)
+	 if (hs->HashType() != "Checksum-FileSize")
+	    return true;
+      return false;
+   }
    return find(forcedType) != NULL;
 }
 									/*}}}*/
@@ -201,6 +209,9 @@ bool HashStringList::VerifyFile(std::string filename) const		/*{{{*/
    HashString const * const hs = find(NULL);
    if (hs == NULL || hs->VerifyFile(filename) == false)
       return false;
+   HashString const * const hsf = find("Checksum-FileSize");
+   if (hsf != NULL && hsf->VerifyFile(filename) == false)
+      return false;
    return true;
 }
 									/*}}}*/
@@ -235,6 +246,14 @@ bool HashStringList::operator!=(HashStringList const &other) const
 }
 									/*}}}*/
 
+// PrivateHashes							/*{{{*/
+class PrivateHashes {
+public:
+   unsigned long long FileSize;
+
+   PrivateHashes() : FileSize(0) {}
+};
+									/*}}}*/
 // Hashes::Add* - Add the contents of data or FD			/*{{{*/
 bool Hashes::Add(const unsigned char * const Data,unsigned long long const Size, unsigned int const Hashes)
 {
@@ -254,6 +273,7 @@ bool Hashes::Add(const unsigned char * const Data,unsigned long long const Size,
 #if __GNUC__ >= 4
 	#pragma GCC diagnostic pop
 #endif
+   d->FileSize += Size;
    return Res;
 }
 bool Hashes::AddFD(int const Fd,unsigned long long Size, unsigned int const Hashes)
@@ -314,15 +334,17 @@ HashStringList Hashes::GetHashStringList()
 #if __GNUC__ >= 4
 	#pragma GCC diagnostic pop
 #endif
+   std::string SizeStr;
+   strprintf(SizeStr, "%llu", d->FileSize);
+   hashes.push_back(HashString("Checksum-FileSize", SizeStr));
    return hashes;
 }
 #if __GNUC__ >= 4
 	#pragma GCC diagnostic push
 	#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-	#pragma GCC diagnostic ignored "-Wsuggest-attribute=const"
 #endif
-Hashes::Hashes() {}
-Hashes::~Hashes() {}
+Hashes::Hashes() { d = new PrivateHashes(); }
+Hashes::~Hashes() { delete d; }
 #if __GNUC__ >= 4
 	#pragma GCC diagnostic pop
 #endif

apt-pkg/contrib/hashes.h

@@ -161,10 +161,10 @@ class HashStringList
    std::vector<HashString> list;
 };
 
+class PrivateHashes;
 class Hashes
 {
-   /** \brief dpointer placeholder */
-   void *d;
+   PrivateHashes *d;
 
    public:
    /* those will disappear in the future as it is hard to add new ones this way.

apt-pkg/indexrecords.cc

@@ -116,6 +116,9 @@ bool indexRecords::Load(const string Filename)				/*{{{*/
             indexRecords::checkSum *Sum = new indexRecords::checkSum;
             Sum->MetaKeyFilename = Name;
             Sum->Size = Size;
+	    std::string SizeStr;
+	    strprintf(SizeStr, "%llu", Size);
+	    Sum->Hashes.push_back(HashString("Checksum-FileSize", SizeStr));
 #if __GNUC__ >= 4
        #pragma GCC diagnostic push
        #pragma GCC diagnostic ignored "-Wdeprecated-declarations"

ftparchive/cachedb.cc

@@ -473,6 +473,10 @@ bool CacheDB::GetHashes(bool const GenOnly, unsigned int const DoHashes)
 	    hex2bytes(CurStat.MD5, hs->HashValue().data(), sizeof(CurStat.MD5));
 	    CurStat.Flags |= FlMD5;
 	 }
+	 else if (strcasecmp(hs->HashType().c_str(), "Checksum-FileSize") == 0)
+	 {
+	    // we store it in a different field already
+	 }
 	 else
 	    return _error->Error("Got unknown unrequested hashtype %s", hs->HashType().c_str());
       }

ftparchive/writer.cc

@@ -471,6 +471,8 @@ bool PackagesWriter::DoPackage(string FileName)
    {
       if (hs->HashType() == "MD5Sum")
 	 Changes.push_back(SetTFRewriteData("MD5sum", hs->HashValue().c_str()));
+      else if (hs->HashType() == "Checksum-FileSize")
+	 continue;
       else
 	 Changes.push_back(SetTFRewriteData(hs->HashType().c_str(), hs->HashValue().c_str()));
    }
@@ -785,7 +787,7 @@ bool SourcesWriter::DoPackage(string FileName)
 
          for (HashStringList::const_iterator hs = Db.HashesList.begin(); hs != Db.HashesList.end(); ++hs)
 	 {
-	    if (hs->HashType() == "MD5Sum")
+	    if (hs->HashType() == "MD5Sum" || hs->HashType() == "Checksum-FileSize")
 	       continue;
 	    char const * fieldname;
 	    std::ostream * out;

test/integration/test-apt-update-filesize-mismatch

@@ -0,0 +1,55 @@
+#!/bin/sh
+set -e
+
+TESTDIR=$(readlink -f $(dirname $0))
+. $TESTDIR/framework
+setupenvironment
+configarchitecture 'i386'
+configcompression 'gz'
+
+insertpackage 'testing' 'foo' 'all' '1'
+insertpackage 'testing' 'foo2' 'all' '1'
+insertsource 'testing' 'foo' 'all' '1'
+insertsource 'testing' 'foo2' 'all' '1'
+
+setupaptarchive --no-update
+changetowebserver
+
+find aptarchive \( -name 'Packages' -o -name 'Sources' -o -name 'Translation-en' \) -delete
+for release in $(find aptarchive -name 'Release'); do
+	cp "$release" "${release}.backup"
+done
+
+testsuccess aptget update
+testsuccess aptcache show foo
+testsuccess aptget install foo -s
+
+for get in $(sed -n 's#^GET /\([^ ]\+\.gz\) HTTP.\+$#\1#p' aptarchive/webserver.log); do
+	for ext in '' '.gz'; do
+		COMPRESSFILE="$get"
+		get="${get}${ext}"
+		FILE="$(basename -s '.gz' "$get")"
+		msgmsg 'Test filesize mismatch with file' "$FILE"
+		rm -rf rootdir/var/lib/apt/lists
+
+		for release in $(find aptarchive -name 'Release'); do
+			SIZE="$(awk "/$FILE\$/ { print \$2; exit }" "${release}.backup")"
+			sed "s# $SIZE # $(($SIZE + 111)) #" "${release}.backup" > "$release"
+		done
+		signreleasefiles
+
+		TEST='testfailure'
+		if expr match "$COMPRESSFILE" '^.*Translation-.*$' >/dev/null; then
+			TEST='testsuccess'
+			unset COMPRESSFILE
+		fi
+		$TEST aptget update -o Debug::pkgAcquire::Worker=1
+		cp rootdir/tmp/${TEST}.output rootdir/tmp/update.output
+		testsuccess grep -E "$(basename -s '.gz' "$COMPRESSFILE").*Hash Sum mismatch" rootdir/tmp/update.output
+		$TEST aptcache show foo
+		$TEST aptget install foo -s
+
+		testfailure aptcache show bar
+		testfailure aptget install bar -s
+	done
+done

test/integration/test-apt-update-hashsum-mismatch

@@ -0,0 +1,49 @@
+#!/bin/sh
+set -e
+
+TESTDIR=$(readlink -f $(dirname $0))
+. $TESTDIR/framework
+setupenvironment
+configarchitecture 'i386'
+configcompression 'gz'
+
+insertpackage 'testing' 'foo' 'all' '1'
+insertpackage 'testing' 'foo2' 'all' '1'
+insertsource 'testing' 'foo' 'all' '1'
+insertsource 'testing' 'foo2' 'all' '1'
+
+setupaptarchive --no-update
+changetowebserver
+
+echo 'Package: bar
+Maintainer: Doctor Evil <evil@example.com>
+Description: come to the dark side
+' > aptarchive/DoctorEvil
+compressfile aptarchive/DoctorEvil
+
+find aptarchive \( -name 'Packages' -o -name 'Sources' -o -name 'Translation-en' \) -delete
+
+testsuccess aptget update
+testsuccess aptcache show foo
+testsuccess aptget install foo -s
+
+for get in $(sed -n 's#^GET /\([^ ]\+\.gz\) HTTP.\+$#\1#p' aptarchive/webserver.log); do
+	msgmsg 'Test hashsum mismatch with file' "$get"
+	rm -rf rootdir/var/lib/apt/lists
+	webserverconfig 'aptwebserver::overwrite' ''
+	webserverconfig "aptwebserver::overwrite::$(printf '%s' "${get}" | sed 's#/#%2F#g' )::filename" '%2FDoctorEvil.gz'
+
+	TEST='testfailure'
+	if expr match "$get" '^.*Translation-.*$' >/dev/null; then
+		TEST='testsuccess'
+		unset get
+	fi
+	$TEST aptget update
+	cp rootdir/tmp/${TEST}.output rootdir/tmp/update.output
+	testsuccess grep -E "$(basename -s '.gz' "$get").*Hash Sum mismatch" rootdir/tmp/update.output
+	$TEST aptcache show foo
+	$TEST aptget install foo -s
+
+	testfailure aptcache show bar
+	testfailure aptget install bar -s
+done

test/integration/test-apt-update-ims

@@ -30,7 +30,7 @@ runtest() {
     
     # ensure that we still do a hash check on ims hit
     msgtest 'Test I-M-S' 'reverify'
-    aptget update -o Debug::pkgAcquire::Auth=1 2>&1 | grep -A1 'RecivedHash:' | grep -q -- '- SHA' && msgpass || msgfail
+    aptget update -o Debug::pkgAcquire::Auth=1 2>&1 | grep -A2 'RecivedHash:' | grep -q -- '- SHA' && msgpass || msgfail
 
     # ensure no leftovers in partial
     testfailure ls "rootdir/var/lib/apt/lists/partial/*"

test/interactive-helper/aptwebserver.cc

@@ -499,9 +499,11 @@ static bool parseFirstLine(int const client, std::string const &request,/*{{{*/
    return true;
 }
 									/*}}}*/
-static bool handleOnTheFlyReconfiguration(int const client, std::string const &request, std::vector<std::string> const &parts)/*{{{*/
+static bool handleOnTheFlyReconfiguration(int const client, std::string const &request, std::vector<std::string> parts)/*{{{*/
 {
    size_t const pcount = parts.size();
+   for (size_t i = 0; i < pcount; ++i)
+      parts[i] = DeQuoteString(parts[i]);
    if (pcount == 4 && parts[1] == "set")
    {
       _config->Set(parts[2], parts[3]);

test/libapt/hashsums_test.cc

@@ -163,30 +163,34 @@ TEST(HashSumsTest, FileBased)
 
    FileFd fd(__FILE__, FileFd::ReadOnly);
    EXPECT_TRUE(fd.IsOpen());
+   std::string FileSize;
+   strprintf(FileSize, "%llu", fd.FileSize());
 
    {
       Hashes hashes;
       hashes.AddFD(fd.Fd());
       HashStringList list = hashes.GetHashStringList();
       EXPECT_FALSE(list.empty());
-      EXPECT_EQ(4, list.size());
+      EXPECT_EQ(5, list.size());
       EXPECT_EQ(md5.Value(), list.find("MD5Sum")->HashValue());
       EXPECT_EQ(sha1.Value(), list.find("SHA1")->HashValue());
       EXPECT_EQ(sha256.Value(), list.find("SHA256")->HashValue());
       EXPECT_EQ(sha512.Value(), list.find("SHA512")->HashValue());
+      EXPECT_EQ(FileSize, list.find("Checksum-FileSize")->HashValue());
    }
-   unsigned long sz = fd.FileSize();
+   unsigned long long sz = fd.FileSize();
    fd.Seek(0);
    {
       Hashes hashes;
       hashes.AddFD(fd.Fd(), sz);
       HashStringList list = hashes.GetHashStringList();
       EXPECT_FALSE(list.empty());
-      EXPECT_EQ(4, list.size());
+      EXPECT_EQ(5, list.size());
       EXPECT_EQ(md5.Value(), list.find("MD5Sum")->HashValue());
       EXPECT_EQ(sha1.Value(), list.find("SHA1")->HashValue());
       EXPECT_EQ(sha256.Value(), list.find("SHA256")->HashValue());
       EXPECT_EQ(sha512.Value(), list.find("SHA512")->HashValue());
+      EXPECT_EQ(FileSize, list.find("Checksum-FileSize")->HashValue());
    }
    fd.Seek(0);
    {
@@ -279,37 +283,46 @@ TEST(HashSumsTest, HashStringList)
    EXPECT_EQ(NULL, list.find(""));
    EXPECT_EQ(NULL, list.find("MD5Sum"));
 
+   // empty lists aren't equal
    HashStringList list2;
    EXPECT_FALSE(list == list2);
    EXPECT_TRUE(list != list2);
 
+   // some hashes don't really contribute to usability
+   list.push_back(HashString("Checksum-FileSize", "29"));
+   EXPECT_FALSE(list.empty());
+   EXPECT_FALSE(list.usable());
+
    Hashes hashes;
    hashes.Add("The quick brown fox jumps over the lazy dog");
    list = hashes.GetHashStringList();
    EXPECT_FALSE(list.empty());
    EXPECT_TRUE(list.usable());
-   EXPECT_EQ(4, list.size());
+   EXPECT_EQ(5, list.size());
    EXPECT_TRUE(NULL != list.find(NULL));
    EXPECT_TRUE(NULL != list.find(""));
    EXPECT_TRUE(NULL != list.find("MD5Sum"));
+   EXPECT_TRUE(NULL != list.find("Checksum-FileSize"));
    EXPECT_TRUE(NULL == list.find("ROT26"));
 
    _config->Set("Acquire::ForceHash", "MD5Sum");
    EXPECT_FALSE(list.empty());
    EXPECT_TRUE(list.usable());
-   EXPECT_EQ(4, list.size());
+   EXPECT_EQ(5, list.size());
    EXPECT_TRUE(NULL != list.find(NULL));
    EXPECT_TRUE(NULL != list.find(""));
    EXPECT_TRUE(NULL != list.find("MD5Sum"));
+   EXPECT_TRUE(NULL != list.find("Checksum-FileSize"));
    EXPECT_TRUE(NULL == list.find("ROT26"));
 
    _config->Set("Acquire::ForceHash", "ROT26");
    EXPECT_FALSE(list.empty());
    EXPECT_FALSE(list.usable());
-   EXPECT_EQ(4, list.size());
+   EXPECT_EQ(5, list.size());
    EXPECT_TRUE(NULL == list.find(NULL));
    EXPECT_TRUE(NULL == list.find(""));
    EXPECT_TRUE(NULL != list.find("MD5Sum"));
+   EXPECT_TRUE(NULL != list.find("Checksum-FileSize"));
    EXPECT_TRUE(NULL == list.find("ROT26"));
 
    _config->Clear("Acquire::ForceHash");