cosmopolitan/libc/calls/ntaccesscheck.c
Justine Tunney 3e4fd4b0ad Add epoll and do more release readiness changes
This change also pays off some of the remaining technical debt with
stdio, file descriptors, and memory managemnt polyfills.
2020-11-28 12:01:51 -08:00

89 lines
4.3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/nt/enum/accessmask.h"
#include "libc/nt/enum/securityimpersonationlevel.h"
#include "libc/nt/enum/securityinformation.h"
#include "libc/nt/errors.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/genericmapping.h"
#include "libc/nt/struct/privilegeset.h"
#include "libc/nt/struct/securitydescriptor.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/ok.h"
/**
* Asks Microsoft if we're authorized to use a folder or file.
*
* Implementation Details: MSDN documentation imposes no limit on the
* internal size of SECURITY_DESCRIPTOR, which we are responsible for
* allocating. We've selected 1024 which shall hopefully be adequate.
*
* @param flags can have R_OK, W_OK, X_OK, etc.
* @return 0 if authorized, or -1 w/ errno
* @kudos Aaron Ballman for teaching this
* @see libc/sysv/consts.sh
*/
textwindows int ntaccesscheck(const char16_t *pathname, uint32_t flags) {
int rc;
bool32 result;
struct NtGenericMapping mapping;
struct NtPrivilegeSet privileges;
int64_t hToken, hImpersonatedToken;
uint32_t secsize, granted, privsize;
union NtSecurityDescriptorLol {
struct NtSecurityDescriptor s;
char b[1024];
} security;
granted = 0;
result = false;
secsize = sizeof(security);
privsize = sizeof(privileges);
memset(&privileges, 0, sizeof(privileges));
mapping.GenericRead = kNtFileGenericRead;
mapping.GenericWrite = kNtFileGenericWrite;
mapping.GenericExecute = kNtFileGenericExecute;
mapping.GenericAll = kNtFileAllAccess;
MapGenericMask(&flags, &mapping);
hImpersonatedToken = hToken = -1;
if (GetFileSecurity(pathname,
kNtOwnerSecurityInformation |
kNtGroupSecurityInformation |
kNtDaclSecurityInformation,
&security.s, 0, &secsize) &&
OpenProcessToken(GetCurrentProcess(),
kNtTokenImpersonate | kNtTokenQuery | kNtTokenDuplicate |
kNtStandardRightsRead,
&hToken) &&
DuplicateToken(hToken, kNtSecurityImpersonation, &hImpersonatedToken) &&
AccessCheck(&security.s, hImpersonatedToken, flags, &mapping, &privileges,
&privsize, &granted, &result) &&
(result || flags == F_OK)) {
rc = 0;
} else {
rc = __winerr();
}
close(hImpersonatedToken);
close(hToken);
return rc;
}