gpgv: Verify keyrings and dearmor outside apt-key

1 files changed, 54 insertions, 5 deletions

diff --git a/apt-pkg/contrib/gpgv.cc b/apt-pkg/contrib/gpgv.cc
index dd1a279fc..fdc292f4f 100644
--- a/apt-pkg/contrib/gpgv.cc
+++ b/apt-pkg/contrib/gpgv.cc
@@ -168,17 +168,66 @@ void ExecGPGV(std::string const &File, std::string const &FileGPG,
    Args.push_back(aptkey);
    Args.push_back("--quiet");
    Args.push_back("--readonly");
+   auto dearmorKeyOrCheckFormat = [&](std::string const &k) -> std::string
+   {
+      FileFd keyFd(k, FileFd::ReadOnly);
+      if (not keyFd.IsOpen())
+      {
+	 apt_warning(std::cerr, statusfd, fd, "The key(s) in the keyring %s are ignored as the file is not readable by user executing apt-key.\n", k.c_str());
+	 return "";
+      }
+      if (APT::String::Endswith(k, ".gpg") || APT::String::Endswith(k, ".pub"))
+      {
+	 unsigned char c;
+	 if (not keyFd.Read(&c, sizeof(c)))
+	    goto err;
+	 // Identify the leading byte of an OpenPGP public key packet
+	 // 0x98 -- old-format OpenPGP public key packet, up to 255 octets
+	 // 0x99 -- old-format OpenPGP public key packet, 256-65535 octets
+	 // 0xc6 -- new-format OpenPGP public key packet, any length
+	 if (c == 0x98 || c == 0x99 || c == 0xc6)
+	    return k;
+      }
+      else if (APT::String::Endswith(k, ".asc"))
+      {
+	 std::string b64msg;
+	 int state = 0;
+	 for (std::string line; keyFd.ReadLine(line);)
+	 {
+	    line = APT::String::Strip(line);
+	    if (APT::String::Startswith(line, "-----BEGIN PGP PUBLIC KEY BLOCK-----"))
+	       state = 1;
+	    else if (state == 1 && line == "")
+	       state = 2;
+	    else if (state == 2 && line != "" && line[0] != '=' && line[0] != '-')
+	       b64msg += line;
+	    else if (APT::String::Startswith(line, "-----END"))
+	       state = 3;
+	 }
+	 if (state != 3)
+	    goto err;
+
+	 FileFd dearmoredFd;
+	 if (GetTempFile("apt.XXXXXX.gpg", false, &dearmoredFd) == nullptr)
+	    local_exit(EINTERNAL);
+	 if (auto decoded = Base64Decode(b64msg); not decoded.empty())
+	    dearmoredFd.Write(decoded.data(), decoded.size());
+	 local_exit.files.push_back(dearmoredFd.Name());
+	 return dearmoredFd.Name();
+      }
+   err:
+      apt_warning(std::cerr, statusfd, fd, "The key(s) in the keyring %s are ignored as the file has an unsupported filetype.", k.c_str());
+      return "";
+   };
    auto maybeAddKeyring = [&](std::string const &k)
    {
       if (struct stat st; stat(k.c_str(), &st) != 0 || st.st_size == 0)
 	 return;
-      if (access(k.c_str(), R_OK) != 0)
+      if (auto cleanKey = dearmorKeyOrCheckFormat(k); not cleanKey.empty())
       {
-	 apt_warning(std::cerr, statusfd, fd, "The key(s) in the keyring %s are ignored as the file is not readable by user executing apt-key.\n", k.c_str());
-	 return;
+	 Args.push_back("--keyring");
+	 Args.push_back(cleanKey);
       }
-      Args.push_back("--keyring");
-      Args.push_back(k);
       return;
    };