diff options
Diffstat (limited to 'openssl/agent/pkcs11/agent.cxx')
| -rw-r--r-- | openssl/agent/pkcs11/agent.cxx | 621 |
1 files changed, 621 insertions, 0 deletions
diff --git a/openssl/agent/pkcs11/agent.cxx b/openssl/agent/pkcs11/agent.cxx new file mode 100644 index 0000000..12b273c --- /dev/null +++ b/openssl/agent/pkcs11/agent.cxx @@ -0,0 +1,621 @@ +// 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); +} |