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-rw-r--r--openssl/agent/pkcs11/agent.cxx621
1 files changed, 621 insertions, 0 deletions
diff --git a/openssl/agent/pkcs11/agent.cxx b/openssl/agent/pkcs11/agent.cxx
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+++ b/openssl/agent/pkcs11/agent.cxx
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+// file : openssl/agent/pkcs11/agent.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2018 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#include <sys/un.h> // sockaddr_un
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <signal.h> // kill(), sigaction(), sigemptyset(), SIG*
+#include <unistd.h> // fork(), getpid(), dup2(), setsid()
+#include <termios.h> // tcgetattr(), tcsetattr()
+
+#include <csignal> // sig_atomic_t
+#include <cstring> // strlen(), strcpy(), memset(), memcmp()
+#include <iostream>
+
+#include <iostream> // cout
+
+#include <libbutl/pager.mxx>
+
+#include <openssl/protocol.hxx>
+#include <openssl/diagnostics.hxx>
+
+#include <openssl/agent/pkcs11/url.hxx>
+#include <openssl/agent/pkcs11/options.hxx>
+#include <openssl/agent/pkcs11/private-key.hxx>
+
+namespace openssl
+{
+ namespace agent
+ {
+ namespace pkcs11
+ {
+ using namespace std;
+ using namespace butl;
+
+ static void
+ pin_prompt (const string& prompt, char*, size_t);
+
+ // The agent daemon top-level function.
+ //
+ static int
+ daemon (const options&,
+ identity&&,
+ access&&,
+ auto_fd&& sock,
+ char* pin) noexcept;
+
+ static int
+ main (int argc, char* argv[])
+ try
+ {
+ cli::argv_scanner scan (argc, argv);
+
+ // Parse options.
+ //
+ options ops;
+ ops.parse (scan);
+
+ // Version.
+ //
+ if (ops.version ())
+ {
+ cout << "openssl-agent-pkcs11 " << OPENSSL_AGENT_VERSION_ID << endl
+ << "libbutl " << LIBBUTL_VERSION_ID << endl
+ << "Copyright (c) 2014-2018 Code Synthesis Ltd" << endl
+ << "This is free software released under the MIT license."
+ << endl;
+
+ return 0;
+ }
+
+ // Help.
+ //
+ if (ops.help ())
+ {
+ pager p ("openssl-agent-pkcs11 help", false);
+ print_openssl_agent_pkcs11_usage (p.stream ());
+
+ // If the pager failed, assume it has issued some diagnostics.
+ //
+ return p.wait () ? 0 : 1;
+ }
+
+ // Parse arguments.
+ //
+ identity key_identity;
+ access key_access;
+
+ try
+ {
+ string u (scan.more () ? scan.next () : "");
+ if (u.empty ())
+ fail << "private key URL argument expected";
+
+ url key_url (u);
+
+ key_identity = identity (key_url);
+ key_access = access (key_url);
+ }
+ catch (const invalid_argument& e)
+ {
+ fail << "invalid PKCS#11 URL: " << e;
+ }
+
+ try
+ {
+ // Prompt the user for a token PIN unless it is already specified as
+ // an access attribute in the URL.
+ //
+ char pin[65]; // NULL character-terminated PIN.
+
+ if (!key_access.pin_value)
+ pin_prompt ("Enter PIN for PKCS#11", pin, sizeof (pin));
+
+ // Open the agent communication socket and fail if the path is
+ // already taken. We could probably deal with the faulty case
+ // ourselves but let's not complicate things for now.
+ //
+ auto_fd sock (socket (AF_UNIX, SOCK_STREAM, 0));
+
+ if (sock.get () == -1)
+ throw_system_error (errno);
+
+ path sock_path (path::temp_path ("openssl-agent-pkcs11"));
+
+ struct sockaddr_un addr;
+ memset (&addr, 0, sizeof (addr));
+ addr.sun_family = AF_UNIX;
+
+ if (sock_path.string ().size () >= sizeof (addr.sun_path))
+ throw_generic_error (ENAMETOOLONG);
+
+ strcpy (addr.sun_path, sock_path.string ().c_str ());
+
+ // Creates the socket filesystem entry.
+ //
+ if (bind (sock.get (),
+ reinterpret_cast<sockaddr*> (&addr),
+ sizeof (addr)) == -1)
+ throw_system_error (errno);
+
+ auto_rmfile rm (sock_path);
+
+ if (listen (sock.get (), 20 /* backlog */) == -1)
+ throw_system_error (errno);
+
+ // Fork off the agent daemon.
+ //
+ pid_t pid (fork ());
+
+ if (pid == -1)
+ throw_system_error (errno);
+
+ // Run the agent daemon in the child process.
+ //
+ if (pid == 0)
+ return daemon (ops,
+ move (key_identity),
+ move (key_access),
+ move (sock),
+ !key_access.pin_value ? pin : nullptr);
+
+ // Erase the no longer needed PIN.
+ //
+ mem_clear (pin, sizeof (pin));
+
+ // The child now is in charge for the socket filesystem entry.
+ //
+ rm.cancel ();
+
+ sock.close ();
+
+ // Send the init request to the agent to make sure that it is alive
+ // and has successfully initialized the key. Issue the received from
+ // the agent diagnostics and exit with non-zero status if the
+ // initialization failed. Note that the daemon will also exit right
+ // after the response in this case.
+ //
+ {
+ sock = connect (sock_path);
+
+ ifdstream is (fddup (sock.get ()));
+ ofdstream os (move (sock));
+
+ os << request ("init");
+ os.close ();
+
+ response r;
+ is >> r;
+
+ if (r.status != 0)
+ {
+ text << r.error;
+ return r.status;
+ }
+ }
+
+ // Let's mimic the 'ssh-agent -s' command output.
+ //
+ cout << "OPENSSL_AGENT_PKCS11_SOCK=" << sock_path << "; "
+ << "export OPENSSL_AGENT_PKCS11_SOCK;\n"
+ << "OPENSSL_AGENT_PKCS11_PID=" << pid << "; "
+ << "export OPENSSL_AGENT_PKCS11_PID;\n"
+ << "echo Agent pid " << pid << endl;
+
+ return 0;
+ }
+ catch (const io_error&)
+ {
+ fail << "unable to communicate with daemon";
+ }
+ catch (const system_error& e)
+ {
+ fail << "unable to start daemon: " << e;
+ }
+
+ return 0;
+ }
+ catch (const failed&)
+ {
+ return 1; // Diagnostics has already been issued.
+ }
+ catch (const cli::exception& e)
+ {
+ error << e;
+ return 1;
+ }
+
+ // Prompt for the PIN.
+ //
+ // We would be happy to use getpass() functions but it is mentioned as
+ // obsolete in the man page and is likely to be removed from the glibc
+ // future versions. Thus, we will provide our own implementation of the
+ // function that is inspired by the openssh implementation.
+ //
+ // Note: _NSIG is Linux-specic.
+ //
+ static volatile sig_atomic_t received_signals[_NSIG];
+
+ extern "C" void
+ handle_signal (int sig)
+ {
+ received_signals[sig] = 1;
+ }
+
+ static void
+ pin_prompt (const string& prompt, char* buf, size_t max_len)
+ {
+ // Note that openssh tries to open /dev/tty for read/write access but
+ // falls back to stdin/stdout on failure. Let's skip the fallback for
+ // simplicity.
+ //
+ try
+ {
+ auto_fd ifd (fdopen ("/dev/tty", fdopen_mode::in));
+ ofdstream os (fdopen ("/dev/tty", fdopen_mode::out));
+
+ // Disable the echo.
+ //
+ termios term_attrs;
+ if (tcgetattr (os.fd (), &term_attrs) == -1)
+ throw_system_error (errno);
+
+ termios na (term_attrs);
+ na.c_lflag &= ~ECHO;
+
+ if (tcsetattr (os.fd (), TCSAFLUSH, &na) == -1)
+ throw_system_error (errno);
+
+ // Catch signals that would otherwise cause the user to end up with
+ // echo turned off in the shell.
+ //
+ for (size_t i (0); i < _NSIG; ++i)
+ received_signals[i] = 0;
+
+ using sigaction_type = struct sigaction;
+
+ sigaction_type sa;
+ memset (&sa, 0, sizeof (sa));
+ sigemptyset (&sa.sa_mask);
+ sa.sa_handler = handle_signal;
+
+ // Save the current signal handlers while setting up the new ones.
+ //
+ vector<pair<int, sigaction_type>> sig_handlers;
+
+ const vector<int> sigs ({
+ SIGALRM,
+ SIGHUP,
+ SIGINT,
+ SIGPIPE,
+ SIGQUIT,
+ SIGTERM,
+ SIGTSTP,
+ SIGTTIN,
+ SIGTTOU});
+
+ for (int s: sigs)
+ {
+ sig_handlers.push_back (make_pair (s, sigaction_type ()));
+
+ if (sigaction (s, &sa, &sig_handlers.back ().second) == -1)
+ throw_system_error (errno);
+ }
+
+ // Restore the echo state and signal handlers and resend the
+ // received signals.
+ //
+ auto restore = [&os, &term_attrs, &sig_handlers] ()
+ {
+ if (tcsetattr (os.fd (), TCSAFLUSH, &term_attrs) == -1)
+ throw_system_error (errno);
+
+ for (const pair<int, sigaction_type>& sa: sig_handlers)
+ {
+ if (sigaction (sa.first, &sa.second, nullptr) == -1)
+ throw_system_error (errno);
+ }
+
+ pid_t pid (getpid ());
+ for (int i (0); i < _NSIG; i++)
+ {
+ if (received_signals[i] != 0 && kill (pid, i) == -1)
+ throw_system_error (errno);
+ }
+ };
+
+ auto rst (make_exception_guard ([&restore] ()
+ {
+ try
+ {
+ restore ();
+ }
+ catch (const system_error&)
+ {
+ // Not much we can do here.
+ //
+ }
+ }));
+
+ // Print prompt.
+ //
+ os << prompt << ": " << flush;
+
+ // Read the PIN.
+ //
+ // Reserve space for the terminating NULL character.
+ //
+ size_t n (max_len - 1);
+ size_t i (0);
+ for (; i < n; ++i)
+ {
+ ssize_t r (read (ifd.get (), buf + i, 1));
+ if (r == -1)
+ throw_system_error (errno);
+
+ if (r == 0 || buf[i] == '\n')
+ break;
+ }
+
+ restore ();
+
+ os << endl;
+ os.close ();
+
+ if (i == n)
+ fail << "PIN is too long";
+
+ buf[i] = '\0';
+ }
+ catch (const system_error& e)
+ {
+ fail << "failed to read PIN: " << e;
+ }
+ }
+
+ // Terminate the daemon.
+ //
+ static volatile sig_atomic_t exit_requested (0); // Can be used as bool.
+
+ extern "C" void
+ handle_term (int /* sig */)
+ {
+ exit_requested = 1;
+
+ // Now accept() will wakeup, set errno to EINTR, and return with -1.
+ //
+ }
+
+ // Run the daemon.
+ //
+ static int
+ daemon (const options& ops,
+ identity&& ki,
+ access&& ka,
+ auto_fd&& sc,
+ char* pin) noexcept
+ try
+ {
+ // Demonize ourselves.
+ //
+ {
+ if (setsid () == -1)
+ throw_system_error (errno);
+
+ path ("/").current_directory ();
+
+ auto_fd nd (fdnull ());
+
+ auto redir = [&nd] (int sd)
+ {
+ if (dup2 (nd.get (), sd) == -1)
+ throw_system_error (errno);
+ };
+
+ redir (0);
+ redir (1);
+ redir (2);
+ }
+
+ auto_fd sock (move (sc));
+ identity key_identity (move (ki));
+ access key_access (move (ka));
+
+ struct sigaction sa;
+ memset (&sa, 0, sizeof (sa));
+ sigemptyset (&sa.sa_mask);
+ sa.sa_handler = handle_term;
+
+ if (sigaction (SIGTERM, &sa, nullptr) == -1)
+ throw_system_error (errno);
+
+ // It would be natural to create the key at the time of receiving the
+ // init request. However, we need to erase the PIN as soon as
+ // possible. Thus, we will create it now. In case of failure we will
+ // save the error to use for the upcoming init request response.
+ //
+ private_key key;
+
+ // If present, indicates that we still expect the init request. Will
+ // set it to nullopt after init request processing.
+ //
+ optional<string> init_error;
+
+ try
+ {
+ optional<simulate_outcome> s;
+ if (ops.simulate_specified ())
+ s = ops.simulate ();
+
+ key = private_key (key_identity, key_access, pin, s);
+ init_error = "";
+ }
+ catch (const invalid_argument& e)
+ {
+ init_error = string ("error: ") + e.what ();
+ }
+ catch (const runtime_error& e)
+ {
+ init_error = string ("error: ") + e.what ();
+ }
+
+ // Erase the no longer needed PIN.
+ //
+ if (pin != nullptr)
+ mem_clear (pin, strlen (pin));
+
+ // Run the request processing loop.
+ //
+ while (true)
+ {
+ // Accept the client connection.
+ //
+ auto_fd fd (
+ accept (sock.get (), nullptr /* addr */, nullptr /* addrlen */));
+
+ if (exit_requested)
+ break;
+
+ if (fd.get () == -1)
+ {
+ if (errno == EINTR || errno == ECONNABORTED || errno == EPROTO)
+ continue;
+
+ throw_system_error (errno);
+ }
+
+ // If we fail to duplicate the file descriptor, then we are probably
+ // out of resources. Anyway we can't do much about it and will bail
+ // out.
+ //
+ ifdstream is (fddup (fd.get ()));
+
+ try
+ {
+ ofdstream os (move (fd));
+
+ // Respond to the client until he sends valid requests.
+ //
+ while (is.peek () != ifdstream::traits_type::eof ())
+ {
+ request rq;
+ is >> rq;
+
+ // The init request must be the first and only one.
+ //
+ if (rq.cmd == "init")
+ {
+ if (!init_error)
+ {
+ os << response ("error: already initialized");
+ break;
+ }
+
+ if (!init_error->empty ())
+ {
+ os << response (*init_error);
+ os.close ();
+
+ throw runtime_error (*init_error);
+ }
+
+ init_error = nullopt; // We don't expect init anymore.
+ os << response (); // Success.
+ continue;
+ }
+
+ if (init_error)
+ {
+ os << response ("error: not initialized");
+ break;
+ }
+
+ // Process the sign request.
+ //
+ if (rq.cmd == "sign")
+ {
+ // Parse and validate the request arguments (key URL and
+ // simulate outcome).
+ //
+ if (rq.args.size () != 2)
+ {
+ os << response ("error: invalid args");
+ break;
+ }
+
+ identity k;
+
+ try
+ {
+ k = identity (url (rq.args[0]));
+ }
+ catch (const invalid_argument& e)
+ {
+ os << response (
+ string ("error: invalid private key URL: ") + e.what ());
+
+ break;
+ }
+
+ optional<simulate_outcome> sim;
+
+ if (!rq.args[1].empty ())
+ try
+ {
+ sim = to_simulate_outcome (rq.args[1]);
+ }
+ catch (const invalid_argument& e)
+ {
+ os << response (string ("error: ") + e.what ());
+ break;
+ }
+
+ if (k != key_identity)
+ {
+ os << response ("error: private key doesn't match");
+ break;
+ }
+
+ try
+ {
+ os << response (key.sign (rq.input, sim));
+ }
+ catch (const runtime_error& e)
+ {
+ os << response (string ("error: ") + e.what ());
+ break;
+ }
+ }
+ }
+
+ // Close the client connection.
+ //
+ is.close ();
+ os.close ();
+ }
+ catch (const io_error&)
+ {
+ // The client is presumably dead.
+ //
+ }
+ }
+
+ return 0;
+ }
+ catch (const std::exception&)
+ {
+ // There is no way we can complain.
+ //
+ return 1;
+ }
+ }
+ }
+}
+
+int
+main (int argc, char* argv[])
+{
+ return openssl::agent::pkcs11::main (argc, argv);
+}