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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
#pragma once
// Get info about named pipe peer
#include <cstdlib> // defines std::abort()
#include <windows.h>
#include <sddl.h>
#include <aclapi.h>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/hexstr.hpp>
#include <openvpn/buffer/buffer.hpp>
#include <openvpn/win/winerr.hpp>
#include <openvpn/win/scoped_handle.hpp>
#include <openvpn/win/secattr.hpp>
namespace openvpn::Win {
struct NamedPipeImpersonate
{
OPENVPN_EXCEPTION(named_pipe_impersonate);
NamedPipeImpersonate(const HANDLE pipe)
{
if (!::ImpersonateNamedPipeClient(pipe))
{
const Win::LastError err;
OPENVPN_THROW(named_pipe_impersonate, "ImpersonateNamedPipeClient failed: " << err.message());
}
}
~NamedPipeImpersonate()
{
if (!::RevertToSelf())
{
OPENVPN_LOG("NamedPipeImpersonate: RevertToSelf failed, must abort");
std::abort();
}
}
};
struct NamedPipePeerInfo
{
OPENVPN_EXCEPTION(npinfo_error);
// Get process handle given PID.
static Win::ScopedHANDLE get_process(const ULONG pid, const bool limited)
{
// open process
Win::ScopedHANDLE proc(::OpenProcess(
limited ? (PROCESS_QUERY_LIMITED_INFORMATION | SYNCHRONIZE) : PROCESS_ALL_ACCESS,
FALSE,
pid));
if (!proc.defined())
{
const Win::LastError err;
OPENVPN_THROW(npinfo_error, "OpenProcess failed: " << err.message());
}
return proc;
}
// Servers must call this method to modify their process
// access rights to grant clients the
// PROCESS_QUERY_LIMITED_INFORMATION right, so that clients
// can validate the server's exe path via get_exe_path().
static void allow_client_query()
{
SecurityAttributes sa(
"D:" // discretionary ACL
"(A;OICI;0x101000;;;S-1-1-0)" // grant PROCESS_QUERY_LIMITED_INFORMATION and SYNCHRONIZE access to Everyone
,
false,
"client query");
ACL *dacl;
BOOL bDaclPresent, bDaclDefaulted;
if (!::GetSecurityDescriptorDacl(sa.sa.lpSecurityDescriptor,
&bDaclPresent,
&dacl,
&bDaclDefaulted))
{
const Win::LastError err;
OPENVPN_THROW(npinfo_error, "allow_client_query: GetSecurityDescriptorDacl failed: " << err.message());
}
if (!bDaclPresent)
OPENVPN_THROW(npinfo_error, "allow_client_query: missing DACL");
const DWORD ssi_status = ::SetSecurityInfo(
::GetCurrentProcess(),
SE_KERNEL_OBJECT,
DACL_SECURITY_INFORMATION,
NULL,
NULL,
dacl,
NULL);
if (ssi_status != ERROR_SUCCESS)
{
const Win::Error err(ssi_status);
OPENVPN_THROW(npinfo_error, "allow_client_query: SetSecurityInfo failed: " << err.message());
}
}
// Get PID of process at other end of named pipe
static ULONG get_pid(const HANDLE np_handle, const bool client)
{
ULONG pid = 0;
if (client)
{
if (!::GetNamedPipeClientProcessId(np_handle, &pid))
{
const Win::LastError err;
OPENVPN_THROW(npinfo_error, "GetNamedPipeClientProcessId failed: " << err.message());
}
}
else
{
if (!::GetNamedPipeServerProcessId(np_handle, &pid))
{
const Win::LastError err;
OPENVPN_THROW(npinfo_error, "GetNamedPipeServerProcessId failed: " << err.message());
}
}
return pid;
}
// Get exe path given process handle.
static std::wstring get_exe_path(const HANDLE proc)
{
// get exe path
const size_t exe_cap = 256;
wchar_t exe[exe_cap];
DWORD exe_size = exe_cap;
if (!::QueryFullProcessImageNameW(proc, 0, exe, &exe_size))
{
const Win::LastError err;
OPENVPN_THROW(npinfo_error, "QueryFullProcessImageNameW failed: " << err.message());
}
return std::wstring(exe, exe_size);
}
};
struct NamedPipePeerInfoCS : public NamedPipePeerInfo
{
NamedPipePeerInfoCS(const HANDLE handle, const bool client)
{
const ULONG pid = get_pid(handle, client);
proc = get_process(pid, !client);
exe_path = get_exe_path(proc());
}
Win::ScopedHANDLE proc;
std::wstring exe_path;
};
// Used by server to get info about clients
struct NamedPipePeerInfoClient : public NamedPipePeerInfoCS
{
NamedPipePeerInfoClient(const HANDLE handle)
: NamedPipePeerInfoCS(handle, true)
{
}
};
// Used by clients to get info about the server
struct NamedPipePeerInfoServer : public NamedPipePeerInfoCS
{
NamedPipePeerInfoServer(const HANDLE handle)
: NamedPipePeerInfoCS(handle, false)
{
}
};
} // namespace openvpn::Win
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