Support subkeys properly in Signed-By options

If we limit a file to be signed by a certain key it should usually
accept also being signed by any of this keys subkeys instead of
requiring each subkey to be listed explicitly. If the later is really
wanted we support now also the same syntax as gpg does with appending an
exclamation mark at the end of the fingerprint to force no mapping.

9 files changed, 190 insertions, 61 deletions

diff --git a/apt-pkg/deb/debmetaindex.cc b/apt-pkg/deb/debmetaindex.cc
index 9c7c70784..1afcdf2c0 100644
--- a/apt-pkg/deb/debmetaindex.cc
+++ b/apt-pkg/deb/debmetaindex.cc
@@ -28,6 +28,57 @@
 
 #include <apti18n.h>
 
+static std::string transformFingergrpints(std::string finger) /*{{{*/
+{
+   std::transform(finger.begin(), finger.end(), finger.begin(), ::toupper);
+   if (finger.length() == 40)
+   {
+      if (finger.find_first_not_of("0123456789ABCDEF") == std::string::npos)
+	 return finger;
+   }
+   else if (finger.length() == 41)
+   {
+      auto bang = finger.find_first_not_of("0123456789ABCDEF");
+      if (bang == 40 && finger[bang] == '!')
+	 return finger;
+   }
+   return "";
+}
+									/*}}}*/
+static std::string transformFingergrpintsWithFilenames(std::string const &finger) /*{{{*/
+{
+   // no check for existence as we could be chrooting later or such things
+   if (finger.empty() == false && finger[0] == '/')
+      return finger;
+   return transformFingergrpints(finger);
+}
+									/*}}}*/
+static std::string NormalizeSignedBy(std::string SignedBy, bool const SupportFilenames) /*{{{*/
+{
+   // we could go all fancy and allow short/long/string matches as gpgv/apt-key does,
+   // but fingerprints are harder to fake than the others and this option is set once,
+   // not interactively all the time so easy to type is not really a concern.
+   std::transform(SignedBy.begin(), SignedBy.end(), SignedBy.begin(), [](char const c) {
+      return (isspace(c) == 0) ? c : ',';
+   });
+   auto fingers = VectorizeString(SignedBy, ',');
+   auto const isAnEmptyString = [](std::string const &s) { return s.empty(); };
+   fingers.erase(std::remove_if(fingers.begin(), fingers.end(), isAnEmptyString), fingers.end());
+   if (unlikely(fingers.empty()))
+      return "";
+   if (SupportFilenames)
+      std::transform(fingers.begin(), fingers.end(), fingers.begin(), transformFingergrpintsWithFilenames);
+   else
+      std::transform(fingers.begin(), fingers.end(), fingers.begin(), transformFingergrpints);
+   if (std::any_of(fingers.begin(), fingers.end(), isAnEmptyString))
+      return "";
+   std::stringstream os;
+   std::copy(fingers.begin(), fingers.end() - 1, std::ostream_iterator<std::string>(os, ","));
+   os << *fingers.rbegin();
+   return os.str();
+}
+									/*}}}*/
+
 class APT_HIDDEN debReleaseIndexPrivate					/*{{{*/
 {
    public:
@@ -566,26 +617,9 @@ bool debReleaseIndex::Load(std::string const &Filename, std::string * const Erro
    auto Sign = Section.FindS("Signed-By");
    if (Sign.empty() == false)
    {
-      std::transform(Sign.begin(), Sign.end(), Sign.begin(), [&](char const c) {
-	 return (isspace(c) == 0) ? c : ',';
-      });
-      auto fingers = VectorizeString(Sign, ',');
-      std::transform(fingers.begin(), fingers.end(), fingers.begin(), [&](std::string finger) {
-	 std::transform(finger.begin(), finger.end(), finger.begin(), ::toupper);
-	 if (finger.length() != 40 || finger.find_first_not_of("0123456789ABCDEF") != std::string::npos)
-	 {
-	    if (ErrorText != NULL)
-	       strprintf(*ErrorText, _("Invalid '%s' entry in Release file %s"), "Signed-By", Filename.c_str());
-	    return std::string();
-	 }
-	 return finger;
-      });
-      if (fingers.empty() == false && std::find(fingers.begin(), fingers.end(), "") == fingers.end())
-      {
-	 std::stringstream os;
-	 std::copy(fingers.begin(), fingers.end(), std::ostream_iterator<std::string>(os, ","));
-	 SignedBy = os.str();
-      }
+      SignedBy = NormalizeSignedBy(Sign, false);
+      if (SignedBy.empty() && ErrorText != NULL)
+	 strprintf(*ErrorText, _("Invalid '%s' entry in Release file %s"), "Signed-By", Filename.c_str());
    }
 
    if (AuthPossible)
@@ -737,38 +771,15 @@ bool debReleaseIndex::SetSignedBy(std::string const &pSignedBy)
 {
    if (SignedBy.empty() == true && pSignedBy.empty() == false)
    {
-      if (pSignedBy[0] == '/') // no check for existence as we could be chrooting later or such things
-	 SignedBy = pSignedBy; // absolute path to a keyring file
-      else
-      {
-	 // we could go all fancy and allow short/long/string matches as gpgv/apt-key does,
-	 // but fingerprints are harder to fake than the others and this option is set once,
-	 // not interactively all the time so easy to type is not really a concern.
-	 auto fingers = VectorizeString(pSignedBy, ',');
-	 std::transform(fingers.begin(), fingers.end(), fingers.begin(), [&](std::string finger) {
-	    std::transform(finger.begin(), finger.end(), finger.begin(), ::toupper);
-	    if (finger.length() != 40 || finger.find_first_not_of("0123456789ABCDEF") != std::string::npos)
-	    {
-	       _error->Error(_("Invalid value set for option %s regarding source %s %s (%s)"), "Signed-By", URI.c_str(), Dist.c_str(), "not a fingerprint");
-	       return std::string();
-	    }
-	    return finger;
-	 });
-	 std::stringstream os;
-	 std::copy(fingers.begin(), fingers.end(), std::ostream_iterator<std::string>(os, ","));
-	 SignedBy = os.str();
-      }
-      // Normalize the string: Remove trailing commas
-      while (SignedBy[SignedBy.size() - 1] == ',')
-	 SignedBy.resize(SignedBy.size() - 1);
+      SignedBy = NormalizeSignedBy(pSignedBy, true);
+      if (SignedBy.empty())
+	 _error->Error(_("Invalid value set for option %s regarding source %s %s (%s)"), "Signed-By", URI.c_str(), Dist.c_str(), "not a fingerprint");
    }
-   else {
-      // Only compare normalized strings
-      auto pSignedByView = APT::StringView(pSignedBy);
-      while (pSignedByView[pSignedByView.size() - 1] == ',')
-	 pSignedByView = pSignedByView.substr(0, pSignedByView.size() - 1);
-      if (pSignedByView != SignedBy)
-	 return _error->Error(_("Conflicting values set for option %s regarding source %s %s: %s != %s"), "Signed-By", URI.c_str(), Dist.c_str(), SignedBy.c_str(), pSignedByView.to_string().c_str());
+   else
+   {
+      auto const normalSignedBy = NormalizeSignedBy(pSignedBy, true);
+      if (normalSignedBy != SignedBy)
+	 return _error->Error(_("Conflicting values set for option %s regarding source %s %s: %s != %s"), "Signed-By", URI.c_str(), Dist.c_str(), SignedBy.c_str(), normalSignedBy.c_str());
    }
    return true;
 }
diff --git a/methods/gpgv.cc b/methods/gpgv.cc
index 84b8c3e59..e2a20722b 100644
--- a/methods/gpgv.cc
+++ b/methods/gpgv.cc
@@ -20,6 +20,7 @@
 #include <array>
 #include <iostream>
 #include <iterator>
+#include <map>
 #include <sstream>
 #include <string>
 #include <vector>
@@ -175,6 +176,7 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
    // Loop over the output of apt-key (which really is gnupg), and check the signatures.
    std::vector<std::string> ValidSigners;
    std::vector<std::string> ErrSigners;
+   std::map<std::string, std::vector<std::string>> SubKeyMapping;
    size_t buffersize = 0;
    char *buffer = NULL;
    bool gotNODATA = false;
@@ -242,6 +244,9 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
          }
 
          ValidSigners.push_back(sig);
+
+	 if (tokens.size() > 9 && sig != tokens[9])
+	    SubKeyMapping[tokens[9]].emplace_back(sig);
       }
       else if (strncmp(buffer, APTKEYWARNING, sizeof(APTKEYWARNING)-1) == 0)
          Warning("%s", buffer + sizeof(APTKEYWARNING));
@@ -265,15 +270,38 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
 	 if (Debug == true)
 	    std::clog << "Key " << good << " is good sig, is it also a valid and allowed one? ";
 	 bool found = false;
-	 for (auto const &l : limitedTo)
+	 for (auto l : limitedTo)
 	 {
-	    if (IsTheSameKey(l, good) == false)
-	       continue;
-	    // GOODSIG might be "just" a longid, so we check VALIDSIG which is always a fingerprint
-	    if (std::find(ValidSigners.begin(), ValidSigners.end(), l) == ValidSigners.end())
-	       continue;
-	    found = true;
-	    break;
+	    bool exactKey = false;
+	    if (APT::String::Endswith(l, "!"))
+	    {
+	       exactKey = true;
+	       l.erase(l.length() - 1);
+	    }
+	    if (IsTheSameKey(l, good))
+	    {
+	       // GOODSIG might be "just" a longid, so we check VALIDSIG which is always a fingerprint
+	       if (std::find(ValidSigners.cbegin(), ValidSigners.cend(), l) == ValidSigners.cend())
+		  continue;
+	       found = true;
+	       break;
+	    }
+	    else if (exactKey == false)
+	    {
+	       auto const master = SubKeyMapping.find(l);
+	       if (master == SubKeyMapping.end())
+		  continue;
+	       for (auto const &sub : master->second)
+		  if (IsTheSameKey(sub, good))
+		  {
+		     if (std::find(ValidSigners.cbegin(), ValidSigners.cend(), sub) == ValidSigners.cend())
+			continue;
+		     found = true;
+		     break;
+		  }
+	       if (found)
+		  break;
+	    }
 	 }
 	 if (Debug)
 	    std::clog << (found ? "yes" : "no") << "\n";
diff --git a/test/integration/framework b/test/integration/framework
index b0456096c..8ec2e80cf 100644
--- a/test/integration/framework
+++ b/test/integration/framework
@@ -1988,6 +1988,7 @@ mapkeynametokeyid() {
 			*Joe*|*Sixpack*|newarchive) echo '5A90D141DBAC8DAE';;
 			*Rex*|*Expired*) echo '4BC0A39C27CE74F9';;
 			*Marvin*|*Paranoid*) echo 'E8525D47528144E2';;
+			*Sebastian*|*Subkey*) echo '5B6896415D44C43E';;
 			oldarchive) echo 'FDD2DB85F68C85A3';;
 			*) echo 'UNKNOWN KEY';;
 		esac
diff --git a/test/integration/sebastiansubkey.master.sec b/test/integration/sebastiansubkey.master.sec
new file mode 100644
index 000000000..4d86fb983
--- /dev/null
+++ b/test/integration/sebastiansubkey.master.sec
diff --git a/test/integration/sebastiansubkey.pub b/test/integration/sebastiansubkey.pub
new file mode 100644
index 000000000..c5f198c77
--- /dev/null
+++ b/test/integration/sebastiansubkey.pub
diff --git a/test/integration/sebastiansubkey.sec b/test/integration/sebastiansubkey.sec
new file mode 100644
index 000000000..fd40889da
--- /dev/null
+++ b/test/integration/sebastiansubkey.sec
diff --git a/test/integration/test-method-gpgv b/test/integration/test-method-gpgv
index 5e00b1f13..2b53648f0 100755
--- a/test/integration/test-method-gpgv
+++ b/test/integration/test-method-gpgv
@@ -40,6 +40,11 @@ testrun() {
 	testgpgv 'Good signed with fingerprint' 'Good: GOODSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE,' '[GNUPG:] GOODSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE Joe Sixpack (APT Testcases Dummy) <joe@example.org>
 [GNUPG:] VALIDSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE 2016-09-01 1472742625 0 4 0 1 11 00 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE'
 
+	testgpgv 'Good subkey signed with long keyid' 'Good: GOODSIG 5B6896415D44C43E,' '[GNUPG:] GOODSIG 5B6896415D44C43E Sebastian Subkey <subkey@example.org>
+[GNUPG:] VALIDSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E 2018-08-16 1534459673 0 4 0 1 11 00 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE'
+	testgpgv 'Good subkey signed with fingerprint' 'Good: GOODSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E,' '[GNUPG:] GOODSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E Sebastian Subkey <subkey@example.org>
+[GNUPG:] VALIDSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E 2018-08-16 1534459673 0 4 0 1 11 00 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE'
+
 	testgpgv 'Untrusted signed with long keyid' 'Worthless: 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE,' '[GNUPG:] GOODSIG 5A90D141DBAC8DAE Joe Sixpack (APT Testcases Dummy) <joe@example.org>
 [GNUPG:] VALIDSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE 2016-09-01 1472742625 0 4 0 1 1 00 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE'
 	testsuccess grep '^\s\+Good:\s\+$' method.output
@@ -96,7 +101,33 @@ testgpgv 'Good signed with long keyid but not signed-by key' 'NoPubKey: GOODSIG
 [GNUPG:] VALIDSIG 891CC50E605796A0C6E733F74BC0A39C27CE74F9 2016-09-01 1472742625 0 4 0 1 11 00 891CC50E605796A0C6E733F74BC0A39C27CE74F9'
 testsuccess grep '^\s\+Good:\s\+$' method.output
 testsuccess grep 'verified because the public key is not available: GOODSIG' method.output
-testgpgv 'Good signed with fingerprint' 'NoPubKey: GOODSIG 891CC50E605796A0C6E733F74BC0A39C27CE74F9,' '[GNUPG:] GOODSIG 891CC50E605796A0C6E733F74BC0A39C27CE74F9 Rex Expired <rex@example.org>
+testgpgv 'Good signed with fingerprint but not signed-by key' 'NoPubKey: GOODSIG 891CC50E605796A0C6E733F74BC0A39C27CE74F9,' '[GNUPG:] GOODSIG 891CC50E605796A0C6E733F74BC0A39C27CE74F9 Rex Expired <rex@example.org>
 [GNUPG:] VALIDSIG 891CC50E605796A0C6E733F74BC0A39C27CE74F9 2016-09-01 1472742625 0 4 0 1 11 00 891CC50E605796A0C6E733F74BC0A39C27CE74F9'
 testsuccess grep '^\s\+Good:\s\+$' method.output
 testsuccess grep 'verified because the public key is not available: GOODSIG' method.output
+
+gpgvmethod() {
+	echo '601 Configuration
+Config-Item: Debug::Acquire::gpgv=1
+Config-Item: Dir::Bin::apt-key=./faked-apt-key
+Config-Item: APT::Hashes::SHA1::Weak=true
+
+600 URI Acquire
+URI: file:///dev/null
+Filename: /dev/zero
+Signed-By: 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE!
+' | runapt "${METHODSDIR}/gpgv"
+}
+testgpgv 'Exact matched subkey signed with long keyid' 'Good: GOODSIG 5A90D141DBAC8DAE,' '[GNUPG:] GOODSIG 5A90D141DBAC8DAE Sebastian Subkey <subkey@example.org>
+[GNUPG:] VALIDSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE 2018-08-16 1534459673 0 4 0 1 11 00 4281DEDBD466EAE8C1F4157E5B6896415D44C43E'
+testgpgv 'Exact matched subkey signed with fingerprint' 'Good: GOODSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE,' '[GNUPG:] GOODSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE Sebastian Subkey <subkey@example.org>
+[GNUPG:] VALIDSIG 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE 2018-08-16 1534459673 0 4 0 1 11 00 4281DEDBD466EAE8C1F4157E5B6896415D44C43E'
+
+testgpgv 'Exact unmatched subkey signed with long keyid' 'NoPubKey: GOODSIG 5B6896415D44C43E,' '[GNUPG:] GOODSIG 5B6896415D44C43E Sebastian Subkey <subkey@example.org>
+[GNUPG:] VALIDSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E 2018-08-16 1534459673 0 4 0 1 11 00 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE'
+testsuccess grep '^\s\+Good:\s\+$' method.output
+testsuccess grep 'verified because the public key is not available: GOODSIG' method.output
+testgpgv 'Exact unmatched subkey signed with fingerprint' 'NoPubKey: GOODSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E,' '[GNUPG:] GOODSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E Sebastian Subkey <subkey@example.org>
+[GNUPG:] VALIDSIG 4281DEDBD466EAE8C1F4157E5B6896415D44C43E 2018-08-16 1534459673 0 4 0 1 11 00 34A8E9D18DB320F367E8EAA05A90D141DBAC8DAE'
+testsuccess grep '^\s\+Good:\s\+$' method.output
+testsuccess grep 'verified because the public key is not available: GOODSIG' method.output
diff --git a/test/integration/test-releasefile-verification b/test/integration/test-releasefile-verification
index 36a90f9d5..f61d93f79 100755
--- a/test/integration/test-releasefile-verification
+++ b/test/integration/test-releasefile-verification
@@ -342,6 +342,44 @@ Signed-By: ${MARVIN} ${MARVIN}, \\
 	testsuccessequal "$(cat "${PKGFILE}-new")
 " aptcache show apt
 	installaptnew
+
+	cp -a keys/sebastiansubkey.pub rootdir/etc/apt/trusted.gpg.d/sebastiansubkey.gpg
+	local SEBASTIAN="$(aptkey --keyring keys/sebastiansubkey.pub finger --with-colons | grep -m 1 '^fpr' | cut -d':' -f 10)"
+	msgmsg 'Warm archive with subkey signing' 'Sebastian Subkey'
+	rm -rf rootdir/var/lib/apt/lists
+	cp -a rootdir/var/lib/apt/lists-bak rootdir/var/lib/apt/lists
+	signreleasefiles 'Sebastian Subkey'
+	sed -i "/^Valid-Until: / a\
+Signed-By: ${SEBASTIAN}" rootdir/var/lib/apt/lists/*Release
+	touch -d 'now - 1 year' rootdir/var/lib/apt/lists/*Release
+	successfulaptgetupdate
+	testsuccessequal "$(cat "${PKGFILE}-new")
+" aptcache show apt
+	installaptnew
+
+	msgmsg 'Warm archive with wrong exact subkey signing' 'Sebastian Subkey'
+	rm -rf rootdir/var/lib/apt/lists
+	cp -a rootdir/var/lib/apt/lists-bak rootdir/var/lib/apt/lists
+	sed -i "/^Valid-Until: / a\
+Signed-By: ${SEBASTIAN}!" rootdir/var/lib/apt/lists/*Release
+	touch -d 'now - 1 year' rootdir/var/lib/apt/lists/*Release
+	updatewithwarnings 'W: .* public key is not available: GOODSIG'
+	testsuccessequal "$(cat "${PKGFILE}")
+" aptcache show apt
+	installaptold
+
+	local SUBKEY="$(aptkey --keyring keys/sebastiansubkey.pub finger --with-colons | grep -m 2 '^fpr' | tail -n -1 | cut -d':' -f 10)"
+	msgmsg 'Warm archive with correct exact subkey signing' 'Sebastian Subkey'
+	rm -rf rootdir/var/lib/apt/lists
+	cp -a rootdir/var/lib/apt/lists-bak rootdir/var/lib/apt/lists
+	sed -i "/^Valid-Until: / a\
+Signed-By: ${SUBKEY}!" rootdir/var/lib/apt/lists/*Release
+	touch -d 'now - 1 year' rootdir/var/lib/apt/lists/*Release
+	successfulaptgetupdate
+	testsuccessequal "$(cat "${PKGFILE}-new")
+" aptcache show apt
+	installaptnew
+	rm -f rootdir/etc/apt/trusted.gpg.d/sebastiansubkey.gpg
 }
 
 runtest2() {
diff --git a/test/integration/test-signed-by-option b/test/integration/test-signed-by-option
index 4ab2e28bb..faa7dec44 100755
--- a/test/integration/test-signed-by-option
+++ b/test/integration/test-signed-by-option
@@ -7,7 +7,27 @@ TESTDIR="$(readlink -f "$(dirname "$0")")"
 setupenvironment
 configarchitecture 'amd64'
 
-msgtest "Check that a repository with signed-by and two components works"
+msgtest 'Check that a repository with' 'signed-by and two components works'
 echo 'deb [signed-by=CDE5618B8805FD6E202CE9C2D73C39E56580B386] https://people.debian.org/~jak/debian/ stable main contrib # Äffchen' > rootdir/etc/apt/sources.list
+testsuccess --nomsg aptcache policy
+
+msgtest 'Check that a repository with' 'two fingerprints work'
+echo 'deb [signed-by=CDE5618B8805FD6E202CE9C2D73C39E56580B386,AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA] https://people.debian.org/~jak/debian/ stable main contrib # Äffchen' > rootdir/etc/apt/sources.list
+testsuccess --nomsg aptcache policy
+
+msgtest 'Check that a repository with' 'exact fingerprint works'
+echo 'deb [signed-by=CDE5618B8805FD6E202CE9C2D73C39E56580B386!] https://people.debian.org/~jak/debian/ stable main contrib # Äffchen' > rootdir/etc/apt/sources.list
+testsuccess --nomsg aptcache policy
 
+msgtest 'Check that a repository with' 'whitespaced fingerprints work'
+echo 'deb [signed-by=CDE5618B8805FD6E202CE9C2D73C39E56580B386!,,,,AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA] https://people.debian.org/~jak/debian/ stable main contrib # Äffchen' > rootdir/etc/apt/sources.list
+cat > rootdir/etc/apt/sources.list.d/people.sources <<EOF
+Types: deb
+URIs: mirror+file:/var/lib/apt/mirror.lst
+Suites: stable testing
+Components: main contrib
+Architectures: amd64 i386
+Signed-By: CDE5618B8805FD6E202CE9C2D73C39E56580B386!       AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+    ,  , BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
+EOF
 testsuccess --nomsg aptcache policy