bind9/lib/isc/win32/fsaccess.c

/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

/*
 * Note that Win32 does not have the concept of files having access
 * and ownership bits.  The FAT File system only has a readonly flag
 * for everyone and that's all. NTFS uses ACL's which is a totally
 * different concept of controlling access.
 *
 * This code needs to be revisited to set up proper access control for
 * NTFS file systems.  Nothing can be done for FAT file systems.
 */

#include <aclapi.h>
#include <errno.h>
#include <io.h>
#include <stdbool.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <isc/file.h>
#include <isc/stat.h>
#include <isc/string.h>

#include "errno2result.h"

/*
 * The OS-independent part of the API is in lib/isc.
 */
#include "../fsaccess.c"

/* Store the user account name locally */
static char username[255] = "\0";
static DWORD namelen = 0;

/*
 * In order to set or retrieve access information, we need to obtain
 * the File System type.  These could be UNC-type shares.
 */

BOOL
is_ntfs(const char *file) {
	char drive[255];
	char FSType[20];
	char tmpbuf[256];
	char *machinename;
	char *sharename;
	char filename[1024];
	char *last;

	REQUIRE(filename != NULL);

	if (isc_file_absolutepath(file, filename, sizeof(filename)) !=
	    ISC_R_SUCCESS) {
		return (FALSE);
	}

	/*
	 * Look for c:\path\... style, c:/path/... or \\computer\shar\path...
	 * the UNC style file specs
	 */
	if (isalpha(filename[0]) && filename[1] == ':' &&
	    (filename[2] == '\\' || filename[2] == '/'))
	{
		/* Copy 'c:\' or 'c:/' and NUL terminate. */
		strlcpy(drive, filename, ISC_MIN(3 + 1, sizeof(drive)));
	} else if ((filename[0] == '\\') && (filename[1] == '\\')) {
		/* Find the machine and share name and rebuild the UNC */
		strlcpy(tmpbuf, filename, sizeof(tmpbuf));
		machinename = strtok_r(tmpbuf, "\\", &last);
		sharename = strtok_r(NULL, "\\", &last);
		strlcpy(drive, "\\\\", sizeof(drive));
		strlcat(drive, machinename, sizeof(drive));
		strlcat(drive, "\\", sizeof(drive));
		strlcat(drive, sharename, sizeof(drive));
		strlcat(drive, "\\", sizeof(drive));
	} else { /* Not determinable */
		return (FALSE);
	}

	GetVolumeInformation(drive, NULL, 0, NULL, 0, NULL, FSType,
			     sizeof(FSType));
	if (strcmp(FSType, "NTFS") == 0) {
		return (TRUE);
	} else {
		return (FALSE);
	}
}

/*
 * If it's not NTFS, we assume that it is FAT and proceed
 * with almost nothing to do. Only the write flag can be set or
 * cleared.
 */
isc_result_t
FAT_fsaccess_set(const char *path, isc_fsaccess_t access) {
	int mode;
	isc_fsaccess_t bits;

	/*
	 * Done with checking bad bits.  Set mode_t.
	 */
	mode = 0;

#define SET_AND_CLEAR1(modebit)     \
	if ((access & bits) != 0) { \
		mode |= modebit;    \
		access &= ~bits;    \
	}
#define SET_AND_CLEAR(user, group, other) \
	SET_AND_CLEAR1(user);             \
	bits <<= STEP;                    \
	SET_AND_CLEAR1(group);            \
	bits <<= STEP;                    \
	SET_AND_CLEAR1(other);

	bits = ISC_FSACCESS_READ | ISC_FSACCESS_LISTDIRECTORY;

	SET_AND_CLEAR(S_IRUSR, S_IRGRP, S_IROTH);

	bits = ISC_FSACCESS_WRITE | ISC_FSACCESS_CREATECHILD |
	       ISC_FSACCESS_DELETECHILD;

	SET_AND_CLEAR(S_IWUSR, S_IWGRP, S_IWOTH);

	INSIST(access == 0);

	if (_chmod(path, mode) < 0) {
		return (isc__errno2result(errno));
	}

	return (ISC_R_SUCCESS);
}

isc_result_t
NTFS_Access_Control(const char *filename, const char *user, int access,
		    bool isdir) {
	SECURITY_DESCRIPTOR sd;
	BYTE aclBuffer[1024];
	PACL pacl = (PACL)&aclBuffer;
	BYTE sidBuffer[100];
	PSID psid = (PSID)&sidBuffer;
	DWORD sidBufferSize = sizeof(sidBuffer);
	BYTE adminSidBuffer[100];
	PSID padminsid = (PSID)&adminSidBuffer;
	DWORD adminSidBufferSize = sizeof(adminSidBuffer);
	BYTE otherSidBuffer[100];
	PSID pothersid = (PSID)&otherSidBuffer;
	DWORD otherSidBufferSize = sizeof(otherSidBuffer);
	char domainBuffer[100];
	DWORD domainBufferSize = sizeof(domainBuffer);
	SID_NAME_USE snu;
	DWORD NTFSbits;
	int caccess;

	/* Initialize an ACL */
	if (!InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION)) {
		return (ISC_R_NOPERM);
	}
	if (!InitializeAcl(pacl, sizeof(aclBuffer), ACL_REVISION)) {
		return (ISC_R_NOPERM);
	}
	if (!LookupAccountName(0, user, psid, &sidBufferSize, domainBuffer,
			       &domainBufferSize, &snu))
	{
		return (ISC_R_NOPERM);
	}
	domainBufferSize = sizeof(domainBuffer);
	if (!LookupAccountName(0, "Administrators", padminsid,
			       &adminSidBufferSize, domainBuffer,
			       &domainBufferSize, &snu))
	{
		(void)GetLastError();
		return (ISC_R_NOPERM);
	}
	domainBufferSize = sizeof(domainBuffer);
	if (!LookupAccountName(0, "Everyone", pothersid, &otherSidBufferSize,
			       domainBuffer, &domainBufferSize, &snu))
	{
		(void)GetLastError();
		return (ISC_R_NOPERM);
	}

	caccess = access;
	/* Owner check */

	NTFSbits = 0;
	if ((caccess & ISC_FSACCESS_READ) != 0) {
		NTFSbits |= FILE_GENERIC_READ;
	}
	if ((caccess & ISC_FSACCESS_WRITE) != 0) {
		NTFSbits |= FILE_GENERIC_WRITE;
	}
	if ((caccess & ISC_FSACCESS_EXECUTE) != 0) {
		NTFSbits |= FILE_GENERIC_EXECUTE;
	}

	/* For directories check the directory-specific bits */
	if (isdir) {
		if ((caccess & ISC_FSACCESS_CREATECHILD) != 0) {
			NTFSbits |= FILE_ADD_SUBDIRECTORY | FILE_ADD_FILE;
		}
		if ((caccess & ISC_FSACCESS_DELETECHILD) != 0) {
			NTFSbits |= FILE_DELETE_CHILD;
		}
		if ((caccess & ISC_FSACCESS_LISTDIRECTORY) != 0) {
			NTFSbits |= FILE_LIST_DIRECTORY;
		}
		if ((caccess & ISC_FSACCESS_ACCESSCHILD) != 0) {
			NTFSbits |= FILE_TRAVERSE;
		}
	}

	if (NTFSbits ==
	    (FILE_GENERIC_READ | FILE_GENERIC_WRITE | FILE_GENERIC_EXECUTE)) {
		NTFSbits |= FILE_ALL_ACCESS;
	}
	/*
	 * Owner and Administrator also get STANDARD_RIGHTS_ALL
	 * to ensure that they have full control
	 */

	NTFSbits |= STANDARD_RIGHTS_ALL;

	/* Add the ACE to the ACL */
	if (!AddAccessAllowedAce(pacl, ACL_REVISION, NTFSbits, psid)) {
		return (ISC_R_NOPERM);
	}
	if (!AddAccessAllowedAce(pacl, ACL_REVISION, NTFSbits, padminsid)) {
		return (ISC_R_NOPERM);
	}

	/*
	 * Group is ignored since we can be in multiple groups or no group
	 * and its meaning is not clear on Win32
	 */

	caccess = caccess >> STEP;

	/*
	 * Other check.  We translate this to be the same as Everyone
	 */

	caccess = caccess >> STEP;

	NTFSbits = 0;
	if ((caccess & ISC_FSACCESS_READ) != 0) {
		NTFSbits |= FILE_GENERIC_READ;
	}
	if ((caccess & ISC_FSACCESS_WRITE) != 0) {
		NTFSbits |= FILE_GENERIC_WRITE;
	}
	if ((caccess & ISC_FSACCESS_EXECUTE) != 0) {
		NTFSbits |= FILE_GENERIC_EXECUTE;
	}

	/* For directories check the directory-specific bits */
	if (isdir == TRUE) {
		if ((caccess & ISC_FSACCESS_CREATECHILD) != 0) {
			NTFSbits |= FILE_ADD_SUBDIRECTORY | FILE_ADD_FILE;
		}
		if ((caccess & ISC_FSACCESS_DELETECHILD) != 0) {
			NTFSbits |= FILE_DELETE_CHILD;
		}
		if ((caccess & ISC_FSACCESS_LISTDIRECTORY) != 0) {
			NTFSbits |= FILE_LIST_DIRECTORY;
		}
		if ((caccess & ISC_FSACCESS_ACCESSCHILD) != 0) {
			NTFSbits |= FILE_TRAVERSE;
		}
	}
	/* Add the ACE to the ACL */
	if (!AddAccessAllowedAce(pacl, ACL_REVISION, NTFSbits, pothersid)) {
		return (ISC_R_NOPERM);
	}

	if (!SetSecurityDescriptorDacl(&sd, TRUE, pacl, FALSE)) {
		return (ISC_R_NOPERM);
	}
	if (!SetFileSecurity(filename, DACL_SECURITY_INFORMATION, &sd)) {
		return (ISC_R_NOPERM);
	}

	return (ISC_R_SUCCESS);
}

isc_result_t
NTFS_fsaccess_set(const char *path, isc_fsaccess_t access, bool isdir) {
	/*
	 * For NTFS we first need to get the name of the account under
	 * which BIND is running
	 */
	if (namelen == 0) {
		namelen = sizeof(username);
		if (GetUserName(username, &namelen) == 0) {
			return (ISC_R_FAILURE);
		}
	}
	return (NTFS_Access_Control(path, username, access, isdir));
}

isc_result_t
isc_fsaccess_set(const char *path, isc_fsaccess_t access) {
	struct stat statb;
	bool is_dir = false;
	isc_result_t result;

	if (stat(path, &statb) != 0) {
		return (isc__errno2result(errno));
	}

	if ((statb.st_mode & S_IFDIR) != 0) {
		is_dir = true;
	} else if ((statb.st_mode & S_IFREG) == 0) {
		return (ISC_R_INVALIDFILE);
	}

	result = check_bad_bits(access, is_dir);
	if (result != ISC_R_SUCCESS) {
		return (result);
	}

	/*
	 * Determine if this is a FAT or NTFS disk and
	 * call the appropriate function to set the permissions
	 */
	if (is_ntfs(path)) {
		return (NTFS_fsaccess_set(path, access, is_dir));
	} else {
		return (FAT_fsaccess_set(path, access));
	}
}

isc_result_t
isc_fsaccess_changeowner(const char *filename, const char *user) {
	SECURITY_DESCRIPTOR psd;
	BYTE sidBuffer[500];
	BYTE groupBuffer[500];
	PSID psid = (PSID)&sidBuffer;
	DWORD sidBufferSize = sizeof(sidBuffer);
	char domainBuffer[100];
	DWORD domainBufferSize = sizeof(domainBuffer);
	SID_NAME_USE snu;
	PSID pSidGroup = (PSID)&groupBuffer;
	DWORD groupBufferSize = sizeof(groupBuffer);

	/*
	 * Determine if this is a FAT or NTFS disk and
	 * call the appropriate function to set the ownership
	 * FAT disks do not have ownership attributes so it's
	 * a noop.
	 */
	if (is_ntfs(filename) == FALSE) {
		return (ISC_R_SUCCESS);
	}

	if (!InitializeSecurityDescriptor(&psd, SECURITY_DESCRIPTOR_REVISION)) {
		return (ISC_R_NOPERM);
	}

	if (!LookupAccountName(0, user, psid, &sidBufferSize, domainBuffer,
			       &domainBufferSize, &snu))
	{
		return (ISC_R_NOPERM);
	}

	/* Make sure administrators can get to it */
	domainBufferSize = sizeof(domainBuffer);
	if (!LookupAccountName(0, "Administrators", pSidGroup, &groupBufferSize,
			       domainBuffer, &domainBufferSize, &snu))
	{
		return (ISC_R_NOPERM);
	}

	if (!SetSecurityDescriptorOwner(&psd, psid, FALSE)) {
		return (ISC_R_NOPERM);
	}

	if (!SetSecurityDescriptorGroup(&psd, pSidGroup, FALSE)) {
		return (ISC_R_NOPERM);
	}

	if (!SetFileSecurity(filename,
			     OWNER_SECURITY_INFORMATION |
				     GROUP_SECURITY_INFORMATION,
			     &psd))
	{
		return (ISC_R_NOPERM);
	}

	return (ISC_R_SUCCESS);
}