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ipc: remove windows elevation
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Signed-off-by: Jason A. Donenfeld <[email protected]>
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@zx2c4
zx2c4 committed Jun 24, 2021
1 parent e5d564c commit 542b7c0
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Showing 2 changed files with 23 additions and 146 deletions.
101 changes: 18 additions & 83 deletions src/ipc-uapi-windows.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,102 +14,37 @@

static FILE *userspace_interface_file(const char *iface)
{
char fname[MAX_PATH], error_message[1024 * 128] = { 0 };
HANDLE thread_token, process_snapshot, winlogon_process, winlogon_token, duplicated_token, pipe_handle = INVALID_HANDLE_VALUE;
PROCESSENTRY32 entry = { .dwSize = sizeof(PROCESSENTRY32) };
PSECURITY_DESCRIPTOR pipe_sd;
PSID pipe_sid;
char fname[MAX_PATH];
HANDLE pipe_handle;
SID expected_sid;
BOOL ret;
DWORD bytes = sizeof(expected_sid);
PSID pipe_sid;
PSECURITY_DESCRIPTOR pipe_sd;
bool equal;
int fd;
DWORD last_error = ERROR_SUCCESS, bytes = sizeof(expected_sid);
TOKEN_PRIVILEGES privileges = {
.PrivilegeCount = 1,
.Privileges = {{ .Attributes = SE_PRIVILEGE_ENABLED }}
};

if (!LookupPrivilegeValue(NULL, SE_DEBUG_NAME, &privileges.Privileges[0].Luid))
goto err;
if (!CreateWellKnownSid(WinLocalSystemSid, NULL, &expected_sid, &bytes))
goto err;

process_snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if (process_snapshot == INVALID_HANDLE_VALUE)
goto err;
for (ret = Process32First(process_snapshot, &entry); ret; last_error = GetLastError(), ret = Process32Next(process_snapshot, &entry)) {
if (strcasecmp(entry.szExeFile, "winlogon.exe"))
continue;

RevertToSelf();
if (!ImpersonateSelf(SecurityImpersonation))
continue;
if (!OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, FALSE, &thread_token))
continue;
if (!AdjustTokenPrivileges(thread_token, FALSE, &privileges, sizeof(privileges), NULL, NULL)) {
last_error = GetLastError();
CloseHandle(thread_token);
continue;
}
CloseHandle(thread_token);

winlogon_process = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, entry.th32ProcessID);
if (!winlogon_process)
continue;
if (!OpenProcessToken(winlogon_process, TOKEN_IMPERSONATE | TOKEN_DUPLICATE, &winlogon_token))
continue;
CloseHandle(winlogon_process);
if (!DuplicateToken(winlogon_token, SecurityImpersonation, &duplicated_token)) {
last_error = GetLastError();
RevertToSelf();
continue;
}
CloseHandle(winlogon_token);
if (!SetThreadToken(NULL, duplicated_token)) {
last_error = GetLastError();
CloseHandle(duplicated_token);
continue;
}
CloseHandle(duplicated_token);

snprintf(fname, sizeof(fname), "\\\\.\\pipe\\ProtectedPrefix\\Administrators\\WireGuard\\%s", iface);
pipe_handle = CreateFile(fname, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
last_error = GetLastError();
if (pipe_handle == INVALID_HANDLE_VALUE)
continue;
last_error = GetSecurityInfo(pipe_handle, SE_FILE_OBJECT, OWNER_SECURITY_INFORMATION, &pipe_sid, NULL, NULL, NULL, &pipe_sd);
if (last_error != ERROR_SUCCESS) {
CloseHandle(pipe_handle);
continue;
}
last_error = EqualSid(&expected_sid, pipe_sid) ? ERROR_SUCCESS : ERROR_ACCESS_DENIED;
LocalFree(pipe_sd);
if (last_error != ERROR_SUCCESS) {
CloseHandle(pipe_handle);
continue;
}
last_error = ERROR_SUCCESS;
break;
}
RevertToSelf();
CloseHandle(process_snapshot);

if (last_error != ERROR_SUCCESS || pipe_handle == INVALID_HANDLE_VALUE)
snprintf(fname, sizeof(fname), "\\\\.\\pipe\\ProtectedPrefix\\Administrators\\WireGuard\\%s", iface);
pipe_handle = CreateFileA(fname, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
if (pipe_handle == INVALID_HANDLE_VALUE)
goto err;
if (GetSecurityInfo(pipe_handle, SE_FILE_OBJECT, OWNER_SECURITY_INFORMATION, &pipe_sid, NULL, NULL, NULL, &pipe_sd) != ERROR_SUCCESS)
goto err_close;
equal = EqualSid(&expected_sid, pipe_sid);
LocalFree(pipe_sd);
if (!equal)
goto err_close;
fd = _open_osfhandle((intptr_t)pipe_handle, _O_RDWR);
if (fd == -1) {
last_error = GetLastError();
CloseHandle(pipe_handle);
goto err;
return NULL;
}
return _fdopen(fd, "r+");

err_close:
CloseHandle(pipe_handle);
err:
if (last_error == ERROR_SUCCESS)
last_error = GetLastError();
if (last_error == ERROR_SUCCESS)
last_error = ERROR_ACCESS_DENIED;
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, last_error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), error_message, sizeof(error_message) - 1, NULL);
fprintf(stderr, "Error: Unable to open IPC handle via SYSTEM impersonation: %ld: %s\n", last_error, error_message);
errno = EACCES;
return NULL;
}
Expand Down
68 changes: 5 additions & 63 deletions src/ipc-windows.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -311,66 +311,6 @@ skip:;
return handle;
}

static BOOL elevated_ioctl(HANDLE handle, DWORD code, void *in_buf, DWORD in_buf_len, void *out_buf, DWORD out_buf_len, DWORD *bytes_returned)
{
HANDLE thread_token, process_snapshot, winlogon_process, winlogon_token, duplicated_token;
PROCESSENTRY32 entry = { .dwSize = sizeof(PROCESSENTRY32) };
TOKEN_PRIVILEGES privileges = {
.PrivilegeCount = 1,
.Privileges = {{ .Attributes = SE_PRIVILEGE_ENABLED }}
};
SID expected_sid;
DWORD bytes = sizeof(expected_sid);
BOOL ret;

if (!LookupPrivilegeValue(NULL, SE_DEBUG_NAME, &privileges.Privileges[0].Luid))
return FALSE;
if (!CreateWellKnownSid(WinLocalSystemSid, NULL, &expected_sid, &bytes))
return FALSE;

process_snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if (process_snapshot == INVALID_HANDLE_VALUE)
return FALSE;
for (ret = Process32First(process_snapshot, &entry); ret; ret = Process32Next(process_snapshot, &entry)) {
if (strcasecmp(entry.szExeFile, "winlogon.exe"))
continue;

RevertToSelf();
if (!ImpersonateSelf(SecurityImpersonation))
continue;
if (!OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, FALSE, &thread_token))
continue;
if (!AdjustTokenPrivileges(thread_token, FALSE, &privileges, sizeof(privileges), NULL, NULL)) {
CloseHandle(thread_token);
continue;
}
CloseHandle(thread_token);

winlogon_process = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, entry.th32ProcessID);
if (!winlogon_process)
continue;
if (!OpenProcessToken(winlogon_process, TOKEN_IMPERSONATE | TOKEN_DUPLICATE, &winlogon_token))
continue;
CloseHandle(winlogon_process);
if (!DuplicateToken(winlogon_token, SecurityImpersonation, &duplicated_token)) {
RevertToSelf();
continue;
}
CloseHandle(winlogon_token);
if (!SetThreadToken(NULL, duplicated_token)) {
CloseHandle(duplicated_token);
continue;
}
CloseHandle(duplicated_token);
ret = DeviceIoControl(handle, code, in_buf, in_buf_len, out_buf, out_buf_len, bytes_returned, NULL);
break;
}

RevertToSelf();
CloseHandle(process_snapshot);
return ret;
}

static int kernel_get_device(struct wgdevice **device, const char *iface)
{
WG_IOCTL_INTERFACE *wg_iface;
Expand All @@ -389,10 +329,10 @@ static int kernel_get_device(struct wgdevice **device, const char *iface)
if (!handle)
return -errno;

while (!elevated_ioctl(handle, WG_IOCTL_GET, NULL, 0, buf, buf_len, &buf_len)) {
while (!DeviceIoControl(handle, WG_IOCTL_GET, NULL, 0, buf, buf_len, &buf_len, NULL)) {
free(buf);
if (GetLastError() != ERROR_MORE_DATA) {
errno = EIO;
errno = EACCES;
return -errno;
}
buf = malloc(buf_len);
Expand Down Expand Up @@ -586,8 +526,10 @@ static int kernel_set_device(struct wgdevice *dev)
}
wg_iface->PeersCount = peer_count;

if (!elevated_ioctl(handle, WG_IOCTL_SET, wg_iface, buf_len, NULL, 0, NULL))
if (!DeviceIoControl(handle, WG_IOCTL_SET, wg_iface, buf_len, NULL, 0, NULL, NULL)) {
errno = EACCES;
goto out;
}
errno = 0;

out:
Expand Down

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