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ssh: Add support for Putty.

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* agent/gpg-agent.c [W32]: Include Several Windows header.
(opts): Change help text for enable-ssh-support.
(opts, main): Add option --enable-putty-support
(putty_support, PUTTY_IPC_MAGIC, PUTTY_IPC_MAXLEN): New for W32.
(agent_init_default_ctrl): Add and asssert call.
(putty_message_proc, putty_message_thread): New.
(handle_connections) [W32]: Start putty message thread.
* common/sysutils.c (w32_get_user_sid): New for W32 only
* tools/gpgconf-comp.c (gc_options_gpg_agent): Add
--enable-ssh-support and --enable-putty-support.  Make the
configuration group visible at basic level.
* agent/command-ssh.c (serve_mmapped_ssh_request): New for W32 only.
--

This patch enables support for Putty.  It has been tested with Putty
0.62 using an Unix created ssh key copied to the private-keys-v1.d
directory on Windows and with a manually crafted sshcontrol file.  It
also works with a smartcard key.

May thanks to gniibe who implemented a proxy in Python to test the
putty/gpg-agent communication.

Signed-off-by: Werner Koch <wk@gnupg.org>
(cherry picked from commit 9f32499f99a0817f63f7a73b09bdcebe60d4775d)

Resolved conflicts:
	NEWS
	agent/agent.h
	agent/gpg-agent.c: Convert from pth to npth.
	common/sysutils.c
	common/sysutils.h
This commit is contained in:
Werner Koch 2014-03-07 09:46:44 +01:00
parent 179012ddd4
commit 5105c8d2d3
7 changed files with 473 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
NEWS
View File

@ -6,6 +6,9 @@ Noteworthy changes in version 2.1.0-betaN (unreleased)
* The GNU Pth library has been replaced by the new nPth library.
* New option --enable-putty-support to allow gpg-agent to act as a
Pageant replacement including full smartcard support.
* Removed support for the original HKP keyserver which is not anymore
used by any site.

5
agent/agent.h
View File

@ -293,6 +293,11 @@ gpg_error_t pinentry_loopback(ctrl_t, const char *keyword,
unsigned char **buffer, size_t *size,
size_t max_length);
#ifdef HAVE_W32_SYSTEM
int serve_mmapped_ssh_request (ctrl_t ctrl,
unsigned char *request, size_t maxreqlen);
#endif /*HAVE_W32_SYSTEM*/
/*-- command-ssh.c --*/
ssh_control_file_t ssh_open_control_file (void);
void ssh_close_control_file (ssh_control_file_t cf);

146
agent/command-ssh.c
View File

@ -3443,3 +3443,149 @@ start_command_handler_ssh (ctrl_t ctrl, gnupg_fd_t sock_client)
if (stream_sock)
es_fclose (stream_sock);
}
#ifdef HAVE_W32_SYSTEM
/* Serve one ssh-agent request. This is used for the Putty support.
REQUEST is the the mmapped memory which may be accessed up to a
length of MAXREQLEN. Returns 0 on success which also indicates
that a valid SSH response message is now in REQUEST. */
int
serve_mmapped_ssh_request (ctrl_t ctrl,
unsigned char *request, size_t maxreqlen)
{
gpg_error_t err;
int send_err = 0;
int valid_response = 0;
ssh_request_spec_t *spec;
u32 msglen;
estream_t request_stream, response_stream;
if (setup_ssh_env (ctrl))
goto leave; /* Error setting up the environment. */
if (maxreqlen < 5)
goto leave; /* Caller error. */
msglen = uint32_construct (request[0], request[1], request[2], request[3]);
if (msglen < 1 || msglen > maxreqlen - 4)
{
log_error ("ssh message len (%u) out of range", (unsigned int)msglen);
goto leave;
}
spec = request_spec_lookup (request[4]);
if (!spec)
{
send_err = 1; /* Unknown request type. */
goto leave;
}
/* Create a stream object with the data part of the request. */
if (spec->secret_input)
request_stream = es_mopen (NULL, 0, 0, 1, realloc_secure, gcry_free, "r+");
else
request_stream = es_mopen (NULL, 0, 0, 1, gcry_realloc, gcry_free, "r+");
if (!request_stream)
{
err = gpg_error_from_syserror ();
goto leave;
}
/* We have to disable the estream buffering, because the estream
core doesn't know about secure memory. */
if (es_setvbuf (request_stream, NULL, _IONBF, 0))
{
err = gpg_error_from_syserror ();
goto leave;
}
/* Copy the request to the stream but omit the request type. */
err = stream_write_data (request_stream, request + 5, msglen - 1);
if (err)
goto leave;
es_rewind (request_stream);
response_stream = es_fopenmem (0, "r+b");
if (!response_stream)
{
err = gpg_error_from_syserror ();
goto leave;
}
if (opt.verbose)
log_info ("ssh request handler for %s (%u) started\n",
spec->identifier, spec->type);
err = (*spec->handler) (ctrl, request_stream, response_stream);
if (opt.verbose)
{
if (err)
log_info ("ssh request handler for %s (%u) failed: %s\n",
spec->identifier, spec->type, gpg_strerror (err));
else
log_info ("ssh request handler for %s (%u) ready\n",
spec->identifier, spec->type);
}
es_fclose (request_stream);
request_stream = NULL;
if (err)
{
send_err = 1;
goto leave;
}
/* Put the response back into the mmapped buffer. */
{
void *response_data;
size_t response_size;
/* NB: In contrast to the request-stream, the response stream
includes the the message type byte. */
if (es_fclose_snatch (response_stream, &response_data, &response_size))
{
log_error ("snatching ssh response failed: %s",
gpg_strerror (gpg_error_from_syserror ()));
send_err = 1; /* Ooops. */
goto leave;
}
if (opt.verbose > 1)
log_info ("sending ssh response of length %u\n",
(unsigned int)response_size);
if (response_size > maxreqlen - 4)
{
log_error ("invalid length of the ssh response: %s",
gpg_strerror (GPG_ERR_INTERNAL));
es_free (response_data);
send_err = 1;
goto leave;
}
request[0] = response_size >> 24;
request[1] = response_size >> 16;
request[2] = response_size >> 8;
request[3] = response_size >> 0;
memcpy (request+4, response_data, response_size);
es_free (response_data);
valid_response = 1;
}
leave:
if (send_err)
{
request[0] = 0;
request[1] = 0;
request[2] = 0;
request[3] = 1;
request[4] = SSH_RESPONSE_FAILURE;
valid_response = 1;
}
/* Reset the SCD in case it has been used. */
agent_reset_scd (ctrl);
return valid_response? 0 : -1;
}
#endif /*HAVE_W32_SYSTEM*/

254
agent/gpg-agent.c
View File

@ -1,6 +1,7 @@
/* gpg-agent.c - The GnuPG Agent
* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009,
* 2010 Free Software Foundation, Inc.
* Copyright (C) 2013 Werner Koch
*
* This file is part of GnuPG.
*
@ -30,7 +31,16 @@
#include <time.h>
#include <fcntl.h>
#include <sys/stat.h>
#ifndef HAVE_W32_SYSTEM
#ifdef HAVE_W32_SYSTEM
# ifndef WINVER
# define WINVER 0x0500 /* Same as in common/sysutils.c */
# endif
# ifdef HAVE_WINSOCK2_H
# include <winsock2.h>
# endif
# include <aclapi.h>
# include <sddl.h>
#else /*!HAVE_W32_SYSTEM*/
# include <sys/socket.h>
# include <sys/un.h>
#endif /*!HAVE_W32_SYSTEM*/
@ -111,6 +121,7 @@ enum cmd_and_opt_values
oKeepTTY,
oKeepDISPLAY,
oSSHSupport,
oPuttySupport,
oDisableScdaemon,
oDisableCheckOwnSocket,
oWriteEnvFile
@ -186,7 +197,14 @@ static ARGPARSE_OPTS opts[] = {
N_("allow presetting passphrase")},
{ oAllowLoopbackPinentry, "allow-loopback-pinentry", 0,
N_("allow presetting passphrase")},
{ oSSHSupport, "enable-ssh-support", 0, N_("enable ssh-agent emulation") },
{ oSSHSupport, "enable-ssh-support", 0, N_("enable ssh support") },
{ oPuttySupport, "enable-putty-support", 0,
#ifdef HAVE_W32_SYSTEM
N_("enable putty support")
#else
"@"
#endif
},
{ oWriteEnvFile, "write-env-file", 2|8,
N_("|FILE|write environment settings also to FILE")},
{0}
@ -218,6 +236,17 @@ static ARGPARSE_OPTS opts[] = {
#endif
#ifdef HAVE_W32_SYSTEM
/* Flag indicating that support for Putty has been enabled. */
static int putty_support;
/* A magic value used with WM_COPYDATA. */
#define PUTTY_IPC_MAGIC 0x804e50ba
/* To avoid surprises we limit the size of the mapped IPC file to this
value. Putty currently (0.62) uses 8k, thus 16k should be enough
for the foreseeable future. */
#define PUTTY_IPC_MAXLEN 16384
#endif /*HAVE_W32_SYSTEM*/
/* The list of open file descriptors at startup. Note that this list
has been allocated using the standard malloc. */
static int *startup_fd_list;
@ -815,6 +844,13 @@ main (int argc, char **argv )
case oKeepDISPLAY: opt.keep_display = 1; break;
case oSSHSupport: opt.ssh_support = 1; break;
case oPuttySupport:
# ifdef HAVE_W32_SYSTEM
putty_support = 1;
opt.ssh_support = 1;
# endif
break;
case oWriteEnvFile:
if (pargs.r_type)
env_file_name = pargs.r.ret_str;
@ -976,6 +1012,11 @@ main (int argc, char **argv )
GC_OPT_FLAG_NONE|GC_OPT_FLAG_RUNTIME);
es_printf ("disable-scdaemon:%lu:\n",
GC_OPT_FLAG_NONE|GC_OPT_FLAG_RUNTIME);
#ifdef HAVE_W32_SYSTEM
es_printf ("enable-putty-support:%lu:\n", GC_OPT_FLAG_NONE);
#else
es_printf ("enable-ssh-support:%lu:\n", GC_OPT_FLAG_NONE);
#endif
agent_exit (0);
}
@ -1311,6 +1352,8 @@ agent_exit (int rc)
static void
agent_init_default_ctrl (ctrl_t ctrl)
{
assert (ctrl->session_env);
/* Note we ignore malloc errors because we can't do much about it
and the request will fail anyway shortly after this
initialization. */
@ -1328,7 +1371,6 @@ agent_init_default_ctrl (ctrl_t ctrl)
xfree (ctrl->lc_messages);
ctrl->lc_messages = default_lc_messages? xtrystrdup (default_lc_messages)
/**/ : NULL;
ctrl->cache_ttl_opt_preset = CACHE_TTL_OPT_PRESET;
}
@ -1820,6 +1862,196 @@ check_nonce (ctrl_t ctrl, assuan_sock_nonce_t *nonce)
}
#ifdef HAVE_W32_SYSTEM
/* The window message processing function for Putty. Warning: This
code runs as a native Windows thread. Use of our own functions
needs to be bracket with pth_leave/pth_enter. */
static LRESULT CALLBACK
putty_message_proc (HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
int ret = 0;
int w32rc;
COPYDATASTRUCT *cds;
const char *mapfile;
HANDLE maphd;
PSID mysid = NULL;
PSID mapsid = NULL;
void *data = NULL;
PSECURITY_DESCRIPTOR psd = NULL;
ctrl_t ctrl = NULL;
if (msg != WM_COPYDATA)
{
return DefWindowProc (hwnd, msg, wparam, lparam);
}
cds = (COPYDATASTRUCT*)lparam;
if (cds->dwData != PUTTY_IPC_MAGIC)
return 0; /* Ignore data with the wrong magic. */
mapfile = cds->lpData;
if (!cds->cbData || mapfile[cds->cbData - 1])
return 0; /* Ignore empty and non-properly terminated strings. */
if (DBG_ASSUAN)
{
npth_protect ();
log_debug ("ssh map file '%s'", mapfile);
npth_unprotect ();
}
maphd = OpenFileMapping (FILE_MAP_ALL_ACCESS, FALSE, mapfile);
if (DBG_ASSUAN)
{
npth_protect ();
log_debug ("ssh map handle %p\n", maphd);
npth_unprotect ();
}
if (!maphd || maphd == INVALID_HANDLE_VALUE)
return 0;
npth_protect ();
mysid = w32_get_user_sid ();
if (!mysid)
{
log_error ("error getting my sid\n");
goto leave;
}
w32rc = GetSecurityInfo (maphd, SE_KERNEL_OBJECT,
OWNER_SECURITY_INFORMATION,
&mapsid, NULL, NULL, NULL,
&psd);
if (w32rc)
{
log_error ("error getting sid of ssh map file: rc=%d", w32rc);
goto leave;
}
if (DBG_ASSUAN)
{
char *sidstr;
if (!ConvertSidToStringSid (mysid, &sidstr))
sidstr = NULL;
log_debug (" my sid: '%s'", sidstr? sidstr: "[error]");
LocalFree (sidstr);
if (!ConvertSidToStringSid (mapsid, &sidstr))
sidstr = NULL;
log_debug ("ssh map file sid: '%s'", sidstr? sidstr: "[error]");
LocalFree (sidstr);
}
if (!EqualSid (mysid, mapsid))
{
log_error ("ssh map file has a non-matching sid\n");
goto leave;
}
data = MapViewOfFile (maphd, FILE_MAP_ALL_ACCESS, 0, 0, 0);
if (DBG_ASSUAN)
log_debug ("ssh IPC buffer at %p\n", data);
if (!data)
goto leave;
/* log_printhex ("request:", data, 20); */
ctrl = xtrycalloc (1, sizeof *ctrl);
if (!ctrl)
{
log_error ("error allocating connection control data: %s\n",
strerror (errno) );
goto leave;
}
ctrl->session_env = session_env_new ();
if (!ctrl->session_env)
{
log_error ("error allocating session environment block: %s\n",
strerror (errno) );
goto leave;
}
agent_init_default_ctrl (ctrl);
if (!serve_mmapped_ssh_request (ctrl, data, PUTTY_IPC_MAXLEN))
ret = 1; /* Valid ssh message has been constructed. */
agent_deinit_default_ctrl (ctrl);
/* log_printhex (" reply:", data, 20); */
leave:
xfree (ctrl);
if (data)
UnmapViewOfFile (data);
xfree (mapsid);
if (psd)
LocalFree (psd);
xfree (mysid);
CloseHandle (maphd);
npth_unprotect ();
return ret;
}
#endif /*HAVE_W32_SYSTEM*/
#ifdef HAVE_W32_SYSTEM
/* The thread handling Putty's IPC requests. */
static void *
putty_message_thread (void *arg)
{
WNDCLASS wndwclass = {0, putty_message_proc, 0, 0,
NULL, NULL, NULL, NULL, NULL, "Pageant"};
HWND hwnd;
MSG msg;
(void)arg;
if (opt.verbose)
log_info ("putty message loop thread started\n");
/* The message loop runs as thread independent from our nPth system.
This also means that we need to make sure that we switch back to
our system before calling any no-windows function. */
npth_unprotect ();
/* First create a window to make sure that a message queue exists
for this thread. */
if (!RegisterClass (&wndwclass))
{
npth_protect ();
log_error ("error registering Pageant window class");
return NULL;
}
hwnd = CreateWindowEx (0, "Pageant", "Pageant", 0,
0, 0, 0, 0,
HWND_MESSAGE, /* hWndParent */
NULL, /* hWndMenu */
NULL, /* hInstance */
NULL); /* lpParm */
if (!hwnd)
{
npth_protect ();
log_error ("error creating Pageant window");
return NULL;
}
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
/* Back to nPth. */
npth_protect ();
if (opt.verbose)
log_info ("putty message loop thread stopped\n");
return NULL;
}
#endif /*HAVE_W32_SYSTEM*/
/* This is the standard connection thread's main function. */
static void *
start_connection_thread (void *arg)
@ -1920,6 +2152,22 @@ handle_connections (gnupg_fd_t listen_fd, gnupg_fd_t listen_fd_ssh)
# endif
#endif
/* On Windows we need to fire up a separate thread to listen for
requests from Putty (an SSH client), so we can replace Putty's
Pageant (its ssh-agent implementation). */
#ifdef HAVE_W32_SYSTEM
if (putty_support)
{
npth_t thread;
ret = npth_create (&thread, &tattr, putty_message_thread, NULL);
if (ret)
{
log_error ("error spawning putty message loop: %s\n", strerror (ret));
}
}
#endif /*HAVE_W32_SYSTEM*/
/* Set a flag to tell call-scd.c that it may enable event
notifications. */
opt.sigusr2_enabled = 1;

57
common/sysutils.c
View File

@ -1,6 +1,7 @@
/* sysutils.c - system helpers
* Copyright (C) 1998, 1999, 2000, 2001, 2003, 2004,
* 2007, 2008 Free Software Foundation, Inc.
* Copyright (C) 2013 Werner Koch
*
* This file is part of GnuPG.
*
@ -688,3 +689,59 @@ _gnupg_getenv (const char *name)
}
#endif /*HAVE_W32CE_SYSTEM*/
#ifdef HAVE_W32_SYSTEM
/* Return the user's security identifier from the current process. */
PSID
w32_get_user_sid (void)
{
int okay = 0;
HANDLE proc = NULL;
HANDLE token = NULL;
TOKEN_USER *user = NULL;
PSID sid = NULL;
DWORD tokenlen, sidlen;
proc = OpenProcess (PROCESS_QUERY_INFORMATION, FALSE, GetCurrentProcessId());
if (!proc)
goto leave;
if (!OpenProcessToken (proc, TOKEN_QUERY, &token))
goto leave;
if (!GetTokenInformation (token, TokenUser, NULL, 0, &tokenlen)
&& GetLastError() != ERROR_INSUFFICIENT_BUFFER)
goto leave;
user = xtrymalloc (tokenlen);
if (!user)
goto leave;
if (!GetTokenInformation (token, TokenUser, user, tokenlen, &tokenlen))
goto leave;
if (!IsValidSid (user->User.Sid))
goto leave;
sidlen = GetLengthSid (user->User.Sid);
sid = xtrymalloc (sidlen);
if (!sid)
goto leave;
if (!CopySid (sidlen, sid, user->User.Sid))
goto leave;
okay = 1;
leave:
xfree (user);
if (token)
CloseHandle (token);
if (proc)
CloseHandle (proc);
if (!okay)
{
xfree (sid);
sid = NULL;
}
return sid;
}
#endif /*HAVE_W32_SYSTEM*/

1
common/sysutils.h
View File

@ -65,6 +65,7 @@ int gnupg_setenv (const char *name, const char *value, int overwrite);
int gnupg_unsetenv (const char *name);
#ifdef HAVE_W32_SYSTEM
void *w32_get_user_sid (void);
#include "../common/w32help.h"

8
tools/gpgconf-comp.c
View File

@ -492,7 +492,7 @@ static gc_option_t gc_options_gpg_agent[] =
GC_ARG_TYPE_NONE, GC_BACKEND_GPG_AGENT },
{ "Configuration",
GC_OPT_FLAG_GROUP, GC_LEVEL_EXPERT,
GC_OPT_FLAG_GROUP, GC_LEVEL_BASIC,
"gnupg", N_("Options controlling the configuration") },
{ "options", GC_OPT_FLAG_NONE, GC_LEVEL_EXPERT,
"gnupg", "|FILE|read options from FILE",
@ -500,6 +500,12 @@ static gc_option_t gc_options_gpg_agent[] =
{ "disable-scdaemon", GC_OPT_FLAG_NONE, GC_LEVEL_ADVANCED,
"gnupg", "do not use the SCdaemon",
GC_ARG_TYPE_NONE, GC_BACKEND_GPG_AGENT },
{ "enable-ssh-support", GC_OPT_FLAG_NONE, GC_LEVEL_BASIC,
"gnupg", "enable ssh support",
GC_ARG_TYPE_NONE, GC_BACKEND_GPG_AGENT },
{ "enable-putty-support", GC_OPT_FLAG_NONE, GC_LEVEL_BASIC,
"gnupg", "enable putty support",
GC_ARG_TYPE_NONE, GC_BACKEND_GPG_AGENT },
{ "Debug",
GC_OPT_FLAG_GROUP, GC_LEVEL_ADVANCED,