mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-01-10 01:48:00 +00:00
371c68e355
It's really only useful with MinGW rather than a Cygwin toolchain these days, as recent versions of the latter insist against linking with the Cygwin DLL. (I think it may no longer be possible to build with Cygwin out of the box at all these days, but I'm not going to say so without having actually checked that's the case. Settle for listing MinGW first in various comments and docs.)
244 lines
7.1 KiB
C
244 lines
7.1 KiB
C
/*
|
|
* Windows implementation of SSH connection-sharing IPC setup.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <assert.h>
|
|
|
|
#if !defined NO_SECURITY
|
|
|
|
#define DEFINE_PLUG_METHOD_MACROS
|
|
#include "tree234.h"
|
|
#include "putty.h"
|
|
#include "network.h"
|
|
#include "proxy.h"
|
|
#include "ssh.h"
|
|
|
|
#include "wincapi.h"
|
|
#include "winsecur.h"
|
|
|
|
#ifdef COVERITY
|
|
/*
|
|
* The hack I use to build for Coverity scanning, using winegcc and
|
|
* Makefile.mgw, didn't provide some defines in wincrypt.h last time I
|
|
* looked. Therefore, define them myself here, but enclosed in #ifdef
|
|
* COVERITY to ensure I don't make up random nonsense values for any
|
|
* real build.
|
|
*/
|
|
#ifndef CRYPTPROTECTMEMORY_BLOCK_SIZE
|
|
#define CRYPTPROTECTMEMORY_BLOCK_SIZE 16
|
|
#endif
|
|
#ifndef CRYPTPROTECTMEMORY_CROSS_PROCESS
|
|
#define CRYPTPROTECTMEMORY_CROSS_PROCESS 1
|
|
#endif
|
|
#endif
|
|
|
|
#define CONNSHARE_PIPE_PREFIX "\\\\.\\pipe\\putty-connshare"
|
|
#define CONNSHARE_MUTEX_PREFIX "Local\\putty-connshare-mutex"
|
|
|
|
static char *obfuscate_name(const char *realname)
|
|
{
|
|
/*
|
|
* Windows's named pipes all live in the same namespace, so one
|
|
* user can see what pipes another user has open. This is an
|
|
* undesirable privacy leak and in particular permits one user to
|
|
* know what username@host another user is SSHing to, so we
|
|
* protect that information by using CryptProtectMemory (which
|
|
* uses a key built in to each user's account).
|
|
*/
|
|
char *cryptdata;
|
|
int cryptlen;
|
|
SHA256_State sha;
|
|
unsigned char lenbuf[4];
|
|
unsigned char digest[32];
|
|
char retbuf[65];
|
|
int i;
|
|
|
|
cryptlen = strlen(realname) + 1;
|
|
cryptlen += CRYPTPROTECTMEMORY_BLOCK_SIZE - 1;
|
|
cryptlen /= CRYPTPROTECTMEMORY_BLOCK_SIZE;
|
|
cryptlen *= CRYPTPROTECTMEMORY_BLOCK_SIZE;
|
|
|
|
cryptdata = snewn(cryptlen, char);
|
|
memset(cryptdata, 0, cryptlen);
|
|
strcpy(cryptdata, realname);
|
|
|
|
/*
|
|
* CRYPTPROTECTMEMORY_CROSS_PROCESS causes CryptProtectMemory to
|
|
* use the same key in all processes with this user id, meaning
|
|
* that the next PuTTY process calling this function with the same
|
|
* input will get the same data.
|
|
*
|
|
* (Contrast with CryptProtectData, which invents a new session
|
|
* key every time since its API permits returning more data than
|
|
* was input, so calling _that_ and hashing the output would not
|
|
* be stable.)
|
|
*
|
|
* We don't worry too much if this doesn't work for some reason.
|
|
* Omitting this step still has _some_ privacy value (in that
|
|
* another user can test-hash things to confirm guesses as to
|
|
* where you might be connecting to, but cannot invert SHA-256 in
|
|
* the absence of any plausible guess). So we don't abort if we
|
|
* can't call CryptProtectMemory at all, or if it fails.
|
|
*/
|
|
if (got_crypt())
|
|
p_CryptProtectMemory(cryptdata, cryptlen,
|
|
CRYPTPROTECTMEMORY_CROSS_PROCESS);
|
|
|
|
/*
|
|
* We don't want to give away the length of the hostname either,
|
|
* so having got it back out of CryptProtectMemory we now hash it.
|
|
*/
|
|
SHA256_Init(&sha);
|
|
PUT_32BIT_MSB_FIRST(lenbuf, cryptlen);
|
|
SHA256_Bytes(&sha, lenbuf, 4);
|
|
SHA256_Bytes(&sha, cryptdata, cryptlen);
|
|
SHA256_Final(&sha, digest);
|
|
|
|
sfree(cryptdata);
|
|
|
|
/*
|
|
* Finally, make printable.
|
|
*/
|
|
for (i = 0; i < 32; i++) {
|
|
sprintf(retbuf + 2*i, "%02x", digest[i]);
|
|
/* the last of those will also write the trailing NUL */
|
|
}
|
|
|
|
return dupstr(retbuf);
|
|
}
|
|
|
|
static char *make_name(const char *prefix, const char *name)
|
|
{
|
|
char *username, *retname;
|
|
|
|
username = get_username();
|
|
retname = dupprintf("%s.%s.%s", prefix, username, name);
|
|
sfree(username);
|
|
|
|
return retname;
|
|
}
|
|
|
|
Socket new_named_pipe_client(const char *pipename, Plug plug);
|
|
Socket new_named_pipe_listener(const char *pipename, Plug plug);
|
|
|
|
int platform_ssh_share(const char *pi_name, Conf *conf,
|
|
Plug downplug, Plug upplug, Socket *sock,
|
|
char **logtext, char **ds_err, char **us_err,
|
|
int can_upstream, int can_downstream)
|
|
{
|
|
char *name, *mutexname, *pipename;
|
|
HANDLE mutex;
|
|
Socket retsock;
|
|
PSECURITY_DESCRIPTOR psd;
|
|
PACL acl;
|
|
|
|
/*
|
|
* Transform the platform-independent version of the connection
|
|
* identifier into the obfuscated version we'll use for our
|
|
* Windows named pipe and mutex. A side effect of doing this is
|
|
* that it also eliminates any characters illegal in Windows pipe
|
|
* names.
|
|
*/
|
|
name = obfuscate_name(pi_name);
|
|
if (!name) {
|
|
*logtext = dupprintf("Unable to call CryptProtectMemory: %s",
|
|
win_strerror(GetLastError()));
|
|
return SHARE_NONE;
|
|
}
|
|
|
|
/*
|
|
* Make a mutex name out of the connection identifier, and lock it
|
|
* while we decide whether to be upstream or downstream.
|
|
*/
|
|
{
|
|
SECURITY_ATTRIBUTES sa;
|
|
|
|
mutexname = make_name(CONNSHARE_MUTEX_PREFIX, name);
|
|
if (!make_private_security_descriptor(MUTEX_ALL_ACCESS,
|
|
&psd, &acl, logtext)) {
|
|
sfree(mutexname);
|
|
sfree(name);
|
|
return SHARE_NONE;
|
|
}
|
|
|
|
memset(&sa, 0, sizeof(sa));
|
|
sa.nLength = sizeof(sa);
|
|
sa.lpSecurityDescriptor = psd;
|
|
sa.bInheritHandle = FALSE;
|
|
|
|
mutex = CreateMutex(&sa, FALSE, mutexname);
|
|
|
|
if (!mutex) {
|
|
*logtext = dupprintf("CreateMutex(\"%s\") failed: %s",
|
|
mutexname, win_strerror(GetLastError()));
|
|
sfree(mutexname);
|
|
sfree(name);
|
|
LocalFree(psd);
|
|
LocalFree(acl);
|
|
return SHARE_NONE;
|
|
}
|
|
|
|
sfree(mutexname);
|
|
LocalFree(psd);
|
|
LocalFree(acl);
|
|
|
|
WaitForSingleObject(mutex, INFINITE);
|
|
}
|
|
|
|
pipename = make_name(CONNSHARE_PIPE_PREFIX, name);
|
|
|
|
*logtext = NULL;
|
|
|
|
if (can_downstream) {
|
|
retsock = new_named_pipe_client(pipename, downplug);
|
|
if (sk_socket_error(retsock) == NULL) {
|
|
sfree(*logtext);
|
|
*logtext = pipename;
|
|
*sock = retsock;
|
|
sfree(name);
|
|
ReleaseMutex(mutex);
|
|
CloseHandle(mutex);
|
|
return SHARE_DOWNSTREAM;
|
|
}
|
|
sfree(*ds_err);
|
|
*ds_err = dupprintf("%s: %s", pipename, sk_socket_error(retsock));
|
|
sk_close(retsock);
|
|
}
|
|
|
|
if (can_upstream) {
|
|
retsock = new_named_pipe_listener(pipename, upplug);
|
|
if (sk_socket_error(retsock) == NULL) {
|
|
sfree(*logtext);
|
|
*logtext = pipename;
|
|
*sock = retsock;
|
|
sfree(name);
|
|
ReleaseMutex(mutex);
|
|
CloseHandle(mutex);
|
|
return SHARE_UPSTREAM;
|
|
}
|
|
sfree(*us_err);
|
|
*us_err = dupprintf("%s: %s", pipename, sk_socket_error(retsock));
|
|
sk_close(retsock);
|
|
}
|
|
|
|
/* One of the above clauses ought to have happened. */
|
|
assert(*logtext || *ds_err || *us_err);
|
|
|
|
sfree(pipename);
|
|
sfree(name);
|
|
ReleaseMutex(mutex);
|
|
CloseHandle(mutex);
|
|
return SHARE_NONE;
|
|
}
|
|
|
|
void platform_ssh_share_cleanup(const char *name)
|
|
{
|
|
}
|
|
|
|
#else /* !defined NO_SECURITY */
|
|
|
|
#include "noshare.c"
|
|
|
|
#endif /* !defined NO_SECURITY */
|