return GetLastError();
}
+/*
+ * Set an arbitrary security descriptor on an arbitrary file (or directory),
+ * working around bugs and design flaws in the Windows operating system.
+ *
+ * On success, return 0. On failure, return WIMLIB_ERR_SET_SECURITY and set
+ * errno. Note: if WIMLIB_EXTRACT_FLAG_STRICT_ACLS is not set in
+ * ctx->extract_flags, this function succeeds iff any part of the security
+ * descriptor was successfully set.
+ */
static int
win32_set_security_descriptor(const wchar_t *path, const u8 *desc,
size_t desc_size, struct apply_ctx *ctx)
{
SECURITY_INFORMATION info;
HANDLE h;
- DWORD err;
int ret;
+ /* We really just want to set entire the security descriptor as-is, but
+ * all available APIs require specifying the specific parts of the
+ * descriptor being set. Start out by requesting all parts be set. If
+ * permissions problems are encountered, fall back to omitting some
+ * parts (first the SACL, then the DACL, then the owner), unless the
+ * WIMLIB_EXTRACT_FLAG_STRICT_ACLS flag has been enabled. */
info = OWNER_SECURITY_INFORMATION | GROUP_SECURITY_INFORMATION |
DACL_SECURITY_INFORMATION | SACL_SECURITY_INFORMATION;
+
h = INVALID_HANDLE_VALUE;
+ /* Prefer NtSetSecurityObject() to SetFileSecurity(). SetFileSecurity()
+ * itself necessarily uses NtSetSecurityObject() as the latter is the
+ * underlying system call for setting security information, but
+ * SetFileSecurity() opens the handle with NtCreateFile() without
+ * FILE_OPEN_FILE_BACKUP_INTENT. Hence, access checks are done and due
+ * to the Windows security model, even a process running as the
+ * Administrator can have access denied. (Of course, this not mentioned
+ * in the MS "documentation".) */
+
#ifdef WITH_NTDLL
if (func_NtSetSecurityObject) {
- h = win32_open_existing_file(path, MAXIMUM_ALLOWED);
- if (h == INVALID_HANDLE_VALUE) {
- set_errno_from_GetLastError();
- ERROR_WITH_ERRNO("Can't open %ls", path);
+ DWORD dwDesiredAccess;
+
+ /* Open a handle for NtSetSecurityObject() with as many relevant
+ * access rights as possible.
+ *
+ * We don't know which rights will be actually granted. It
+ * could be less than what is needed to actually assign the full
+ * security descriptor, especially if the process is running as
+ * a non-Administrator. However, by default we just do the best
+ * we can, unless WIMLIB_EXTRACT_FLAG_STRICT_ACLS has been
+ * enabled. The MAXIMUM_ALLOWED access right is seemingly
+ * designed for this use case; however, it does not work
+ * properly in all cases: it can cause CreateFile() to fail with
+ * ERROR_ACCESS_DENIED, even though by definition
+ * MAXIMUM_ALLOWED access only requests access rights that are
+ * *not* denied. (Needless to say, MS does not document this
+ * bug.) */
+
+ dwDesiredAccess = WRITE_DAC |
+ WRITE_OWNER |
+ ACCESS_SYSTEM_SECURITY;
+ for (;;) {
+ DWORD err;
+
+ h = win32_open_existing_file(path, dwDesiredAccess);
+ if (h != INVALID_HANDLE_VALUE)
+ break;
+ err = GetLastError();
+ if (err == ERROR_ACCESS_DENIED ||
+ err == ERROR_PRIVILEGE_NOT_HELD)
+ {
+ /* Don't increment partial_security_descriptors
+ * here or check WIMLIB_EXTRACT_FLAG_STRICT_ACLS
+ * here. It will be done later if needed; here
+ * we are just trying to get as many relevant
+ * access rights as possible. */
+ if (dwDesiredAccess & ACCESS_SYSTEM_SECURITY) {
+ dwDesiredAccess &= ~ACCESS_SYSTEM_SECURITY;
+ continue;
+ }
+ if (dwDesiredAccess & WRITE_DAC) {
+ dwDesiredAccess &= ~WRITE_DAC;
+ continue;
+ }
+ if (dwDesiredAccess & WRITE_OWNER) {
+ dwDesiredAccess &= ~WRITE_OWNER;
+ continue;
+ }
+ }
+ /* Other error, or couldn't open the file even with no
+ * access rights specified. Something else must be
+ * wrong. */
+ set_errno_from_win32_error(err);
return WIMLIB_ERR_SET_SECURITY;
}
}
#endif
+ /* Try setting the security descriptor. */
for (;;) {
+ DWORD err;
+
err = do_win32_set_security_descriptor(h, path, info,
(PSECURITY_DESCRIPTOR)desc);
if (err == ERROR_SUCCESS) {
ret = 0;
break;
}
+
+ /* Failed to set the requested parts of the security descriptor.
+ * If the error was permissions-related, try to set fewer parts
+ * of the security descriptor, unless
+ * WIMLIB_EXTRACT_FLAG_STRICT_ACLS is enabled. */
if ((err == ERROR_PRIVILEGE_NOT_HELD ||
err == ERROR_ACCESS_DENIED) &&
!(ctx->extract_flags & WIMLIB_EXTRACT_FLAG_STRICT_ACLS))
info &= ~OWNER_SECURITY_INFORMATION;
continue;
}
- ctx->partial_security_descriptors--;
- ctx->no_security_descriptors++;
- ret = 0;
- break;
+ /* Nothing left except GROUP, and if we removed it we
+ * wouldn't have anything at all. */
}
+ /* No part of the security descriptor could be set, or
+ * WIMLIB_EXTRACT_FLAG_STRICT_ACLS is enabled and the full
+ * security descriptor could not be set. */
+ if (!(info & SACL_SECURITY_INFORMATION))
+ ctx->partial_security_descriptors--;
set_errno_from_win32_error(err);
ret = WIMLIB_ERR_SET_SECURITY;
break;
}
+
+ /* Close handle opened for NtSetSecurityObject(). */
#ifdef WITH_NTDLL
if (func_NtSetSecurityObject)
CloseHandle(h);
git://wimlib.net / wimlib / blobdiff