path: root/source3/modules/vfs_acl_common.c

/*
 * Store Windows ACLs in data store - common functions.
 * #included into modules/vfs_acl_xattr.c and modules/vfs_acl_tdb.c
 *
 * Copyright (C) Volker Lendecke, 2008
 * Copyright (C) Jeremy Allison, 2009
 *
 * 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; either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "smbd/smbd.h"
#include "system/filesys.h"
#include "../libcli/security/security.h"
#include "../librpc/gen_ndr/ndr_security.h"
#include "../lib/util/bitmap.h"

static NTSTATUS create_acl_blob(const struct security_descriptor *psd,
			DATA_BLOB *pblob,
			uint16_t hash_type,
			uint8_t hash[XATTR_SD_HASH_SIZE]);

static NTSTATUS get_acl_blob(TALLOC_CTX *ctx,
			vfs_handle_struct *handle,
			files_struct *fsp,
			const char *name,
			DATA_BLOB *pblob);

static NTSTATUS store_acl_blob_fsp(vfs_handle_struct *handle,
			files_struct *fsp,
			DATA_BLOB *pblob);

#define HASH_SECURITY_INFO (SECINFO_OWNER | \
				SECINFO_GROUP | \
				SECINFO_DACL | \
				SECINFO_SACL)

/*******************************************************************
 Hash a security descriptor.
*******************************************************************/

static NTSTATUS hash_sd_sha256(struct security_descriptor *psd,
			uint8_t *hash)
{
	DATA_BLOB blob;
	SHA256_CTX tctx;
	NTSTATUS status;

	memset(hash, '\0', XATTR_SD_HASH_SIZE);
	status = create_acl_blob(psd, &blob, XATTR_SD_HASH_TYPE_SHA256, hash);
	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}

	samba_SHA256_Init(&tctx);
	samba_SHA256_Update(&tctx, blob.data, blob.length);
	samba_SHA256_Final(hash, &tctx);

	return NT_STATUS_OK;
}

/*******************************************************************
 Parse out a struct security_descriptor from a DATA_BLOB.
*******************************************************************/

static NTSTATUS parse_acl_blob(const DATA_BLOB *pblob,
				struct security_descriptor **ppdesc,
				uint16_t *p_hash_type,
				uint8_t hash[XATTR_SD_HASH_SIZE])
{
	TALLOC_CTX *ctx = talloc_tos();
	struct xattr_NTACL xacl;
	enum ndr_err_code ndr_err;
	size_t sd_size;

	ndr_err = ndr_pull_struct_blob(pblob, ctx, &xacl,
			(ndr_pull_flags_fn_t)ndr_pull_xattr_NTACL);

	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		DEBUG(5, ("parse_acl_blob: ndr_pull_xattr_NTACL failed: %s\n",
			ndr_errstr(ndr_err)));
		return ndr_map_error2ntstatus(ndr_err);
	}

	switch (xacl.version) {
		case 1:
			*ppdesc = make_sec_desc(ctx, SD_REVISION,
					xacl.info.sd->type | SEC_DESC_SELF_RELATIVE,
					xacl.info.sd->owner_sid,
					xacl.info.sd->group_sid,
					xacl.info.sd->sacl,
					xacl.info.sd->dacl,
					&sd_size);
			/* No hash - null out. */
			*p_hash_type = XATTR_SD_HASH_TYPE_NONE;
			memset(hash, '\0', XATTR_SD_HASH_SIZE);
			break;
		case 2:
			*ppdesc = make_sec_desc(ctx, SD_REVISION,
					xacl.info.sd_hs2->sd->type | SEC_DESC_SELF_RELATIVE,
					xacl.info.sd_hs2->sd->owner_sid,
					xacl.info.sd_hs2->sd->group_sid,
					xacl.info.sd_hs2->sd->sacl,
					xacl.info.sd_hs2->sd->dacl,
					&sd_size);
			/* No hash - null out. */
			*p_hash_type = XATTR_SD_HASH_TYPE_NONE;
			memset(hash, '\0', XATTR_SD_HASH_SIZE);
			break;
		case 3:
			*ppdesc = make_sec_desc(ctx, SD_REVISION,
					xacl.info.sd_hs3->sd->type | SEC_DESC_SELF_RELATIVE,
					xacl.info.sd_hs3->sd->owner_sid,
					xacl.info.sd_hs3->sd->group_sid,
					xacl.info.sd_hs3->sd->sacl,
					xacl.info.sd_hs3->sd->dacl,
					&sd_size);
			*p_hash_type = xacl.info.sd_hs3->hash_type;
			/* Current version 3. */
			memcpy(hash, xacl.info.sd_hs3->hash, XATTR_SD_HASH_SIZE);
			break;
		default:
			return NT_STATUS_REVISION_MISMATCH;
	}

	TALLOC_FREE(xacl.info.sd);

	return (*ppdesc != NULL) ? NT_STATUS_OK : NT_STATUS_NO_MEMORY;
}

/*******************************************************************
 Create a DATA_BLOB from a security descriptor.
*******************************************************************/

static NTSTATUS create_acl_blob(const struct security_descriptor *psd,
			DATA_BLOB *pblob,
			uint16_t hash_type,
			uint8_t hash[XATTR_SD_HASH_SIZE])
{
	struct xattr_NTACL xacl;
	struct security_descriptor_hash_v3 sd_hs3;
	enum ndr_err_code ndr_err;
	TALLOC_CTX *ctx = talloc_tos();

	ZERO_STRUCT(xacl);
	ZERO_STRUCT(sd_hs3);

	xacl.version = 3;
	xacl.info.sd_hs3 = &sd_hs3;
	xacl.info.sd_hs3->sd = discard_const_p(struct security_descriptor, psd);
	xacl.info.sd_hs3->hash_type = hash_type;
	memcpy(&xacl.info.sd_hs3->hash[0], hash, XATTR_SD_HASH_SIZE);

	ndr_err = ndr_push_struct_blob(
			pblob, ctx, &xacl,
			(ndr_push_flags_fn_t)ndr_push_xattr_NTACL);

	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		DEBUG(5, ("create_acl_blob: ndr_push_xattr_NTACL failed: %s\n",
			ndr_errstr(ndr_err)));
		return ndr_map_error2ntstatus(ndr_err);
	}

	return NT_STATUS_OK;
}

/*******************************************************************
 Add in 3 inheritable components for a non-inheritable directory ACL.
 CREATOR_OWNER/CREATOR_GROUP/WORLD.
*******************************************************************/

static void add_directory_inheritable_components(vfs_handle_struct *handle,
                                const char *name,
				SMB_STRUCT_STAT *psbuf,
				struct security_descriptor *psd)
{
	struct connection_struct *conn = handle->conn;
	int num_aces = (psd->dacl ? psd->dacl->num_aces : 0);
	struct smb_filename smb_fname;
	enum security_ace_type acltype;
	uint32_t access_mask;
	mode_t dir_mode;
	mode_t file_mode;
	mode_t mode;
	struct security_ace *new_ace_list = talloc_zero_array(talloc_tos(),
						struct security_ace,
						num_aces + 3);

	if (new_ace_list == NULL) {
		return;
	}

	/* Fake a quick smb_filename. */
	ZERO_STRUCT(smb_fname);
	smb_fname.st = *psbuf;
	smb_fname.base_name = discard_const_p(char, name);

	dir_mode = unix_mode(conn,
			FILE_ATTRIBUTE_DIRECTORY, &smb_fname, NULL);
	file_mode = unix_mode(conn,
			FILE_ATTRIBUTE_ARCHIVE, &smb_fname, NULL);

	mode = dir_mode | file_mode;

	DEBUG(10, ("add_directory_inheritable_components: directory %s, "
		"mode = 0%o\n",
		name,
		(unsigned int)mode ));

	if (num_aces) {
		memcpy(new_ace_list, psd->dacl->aces,
			num_aces * sizeof(struct security_ace));
	}
	access_mask = map_canon_ace_perms(SNUM(conn), &acltype,
				mode & 0700, false);

	init_sec_ace(&new_ace_list[num_aces],
			&global_sid_Creator_Owner,
			acltype,
			access_mask,
			SEC_ACE_FLAG_CONTAINER_INHERIT|
				SEC_ACE_FLAG_OBJECT_INHERIT|
				SEC_ACE_FLAG_INHERIT_ONLY);
	access_mask = map_canon_ace_perms(SNUM(conn), &acltype,
				(mode << 3) & 0700, false);
	init_sec_ace(&new_ace_list[num_aces+1],
			&global_sid_Creator_Group,
			acltype,
			access_mask,
			SEC_ACE_FLAG_CONTAINER_INHERIT|
				SEC_ACE_FLAG_OBJECT_INHERIT|
				SEC_ACE_FLAG_INHERIT_ONLY);
	access_mask = map_canon_ace_perms(SNUM(conn), &acltype,
				(mode << 6) & 0700, false);
	init_sec_ace(&new_ace_list[num_aces+2],
			&global_sid_World,
			acltype,
			access_mask,
			SEC_ACE_FLAG_CONTAINER_INHERIT|
				SEC_ACE_FLAG_OBJECT_INHERIT|
				SEC_ACE_FLAG_INHERIT_ONLY);
	psd->dacl->aces = new_ace_list;
	psd->dacl->num_aces += 3;
}

/*******************************************************************
 Pull a DATA_BLOB from an xattr given a pathname.
 If the hash doesn't match, or doesn't exist - return the underlying
 filesystem sd.
*******************************************************************/

static NTSTATUS get_nt_acl_internal(vfs_handle_struct *handle,
				files_struct *fsp,
				const char *name,
			        uint32_t security_info,
				struct security_descriptor **ppdesc)
{
	DATA_BLOB blob = data_blob_null;
	NTSTATUS status;
	uint16_t hash_type = XATTR_SD_HASH_TYPE_NONE;
	uint8_t hash[XATTR_SD_HASH_SIZE];
	uint8_t hash_tmp[XATTR_SD_HASH_SIZE];
	struct security_descriptor *psd = NULL;
	struct security_descriptor *pdesc_next = NULL;
	bool ignore_file_system_acl = lp_parm_bool(SNUM(handle->conn),
						ACL_MODULE_NAME,
						"ignore system acls",
						false);

	if (fsp && name == NULL) {
		name = fsp->fsp_name->base_name;
	}

	DEBUG(10, ("get_nt_acl_internal: name=%s\n", name));

	/* Get the full underlying sd for the hash
	   or to return as backup. */
	if (fsp) {
		status = SMB_VFS_NEXT_FGET_NT_ACL(handle,
				fsp,
				HASH_SECURITY_INFO,
				&pdesc_next);
	} else {
		status = SMB_VFS_NEXT_GET_NT_ACL(handle,
				name,
				HASH_SECURITY_INFO,
				&pdesc_next);
	}

	if (!NT_STATUS_IS_OK(status)) {
		DEBUG(10, ("get_nt_acl_internal: get_next_acl for file %s "
			"returned %s\n",
			name,
			nt_errstr(status)));
		return status;
	}

	status = get_acl_blob(talloc_tos(), handle, fsp, name, &blob);
	if (!NT_STATUS_IS_OK(status)) {
		DEBUG(10, ("get_nt_acl_internal: get_acl_blob returned %s\n",
			nt_errstr(status)));
		psd = pdesc_next;
		goto out;
	}

	status = parse_acl_blob(&blob, &psd,
				&hash_type, &hash[0]);
	if (!NT_STATUS_IS_OK(status)) {
		DEBUG(10, ("parse_acl_blob returned %s\n",
				nt_errstr(status)));
		psd = pdesc_next;
		goto out;
	}

	/* Ensure the hash type is one we know. */
	switch (hash_type) {
		case XATTR_SD_HASH_TYPE_NONE:
			/* No hash, just return blob sd. */
			goto out;
		case XATTR_SD_HASH_TYPE_SHA256:
			break;
		default:
			DEBUG(10, ("get_nt_acl_internal: ACL blob revision "
				"mismatch (%u) for file %s\n",
				(unsigned int)hash_type,
				name));
			TALLOC_FREE(psd);
			psd = pdesc_next;
			goto out;
	}

	if (ignore_file_system_acl) {
		goto out;
	}

	status = hash_sd_sha256(pdesc_next, hash_tmp);
	if (!NT_STATUS_IS_OK(status)) {
		TALLOC_FREE(psd);
		psd = pdesc_next;
		goto out;
	}

	if (memcmp(&hash[0], &hash_tmp[0], XATTR_SD_HASH_SIZE) == 0) {
		/* Hash matches, return blob sd. */
		DEBUG(10, ("get_nt_acl_internal: blob hash "
			"matches for file %s\n",
			name ));
		goto out;
	}

	/* Hash doesn't match, return underlying sd. */
	TALLOC_FREE(psd);
	psd = pdesc_next;

  out:

	if (psd != pdesc_next) {
		/* We're returning the blob, throw
 		 * away the filesystem SD. */
		TALLOC_FREE(pdesc_next);
	} else {
		SMB_STRUCT_STAT sbuf;
		SMB_STRUCT_STAT *psbuf = &sbuf;
		bool is_directory = false;
		/*
		 * We're returning the underlying ACL from the
		 * filesystem. If it's a directory, and has no
		 * inheritable ACE entries we have to fake them.
		 */
		if (fsp) {
			status = vfs_stat_fsp(fsp);
			if (!NT_STATUS_IS_OK(status)) {
				return status;
			}
			psbuf = &fsp->fsp_name->st;
		} else {
			int ret = vfs_stat_smb_fname(handle->conn,
						name,
						&sbuf);
			if (ret == -1) {
				return map_nt_error_from_unix(errno);
			}
		}
		is_directory = S_ISDIR(psbuf->st_ex_mode);

		if (ignore_file_system_acl) {
			TALLOC_FREE(pdesc_next);
			status = make_default_filesystem_acl(talloc_tos(),
						name,
						psbuf,
						&psd);
			if (!NT_STATUS_IS_OK(status)) {
				return status;
			}
		} else {
			if (is_directory &&
				!sd_has_inheritable_components(psd,
							true)) {
				add_directory_inheritable_components(handle,
							name,
							psbuf,
							psd);
			}
			/* The underlying POSIX module always sets
			   the ~SEC_DESC_DACL_PROTECTED bit, as ACLs
			   can't be inherited in this way under POSIX.
			   Remove it for Windows-style ACLs. */
			psd->type &= ~SEC_DESC_DACL_PROTECTED;
		}
	}

	if (!(security_info & SECINFO_OWNER)) {
		psd->owner_sid = NULL;
	}
	if (!(security_info & SECINFO_GROUP)) {
		psd->group_sid = NULL;
	}
	if (!(security_info & SECINFO_DACL)) {
		psd->type &= ~SEC_DESC_DACL_PRESENT;
		psd->dacl = NULL;
	}
	if (!(security_info & SECINFO_SACL)) {
		psd->type &= ~SEC_DESC_SACL_PRESENT;
		psd->sacl = NULL;
	}

	TALLOC_FREE(blob.data);
	*ppdesc = psd;

	if (DEBUGLEVEL >= 10) {
		DEBUG(10,("get_nt_acl_internal: returning acl for %s is:\n",
			name ));
		NDR_PRINT_DEBUG(security_descriptor, psd);
	}

	return NT_STATUS_OK;
}

/*********************************************************************
 Fetch a security descriptor given an fsp.
*********************************************************************/

static NTSTATUS fget_nt_acl_common(vfs_handle_struct *handle, files_struct *fsp,
        uint32_t security_info, struct security_descriptor **ppdesc)
{
	return get_nt_acl_internal(handle, fsp,
				NULL, security_info, ppdesc);
}

/*********************************************************************
 Fetch a security descriptor given a pathname.
*********************************************************************/

static NTSTATUS get_nt_acl_common(vfs_handle_struct *handle,
        const char *name, uint32_t security_info, struct security_descriptor **ppdesc)
{
	return get_nt_acl_internal(handle, NULL,
				name, security_info, ppdesc);
}

/*********************************************************************
 Store a security descriptor given an fsp.
*********************************************************************/

static NTSTATUS fset_nt_acl_common(vfs_handle_struct *handle, files_struct *fsp,
        uint32_t security_info_sent, const struct security_descriptor *orig_psd)
{
	NTSTATUS status;
	DATA_BLOB blob;
	struct security_descriptor *pdesc_next = NULL;
	struct security_descriptor *psd = NULL;
	uint8_t hash[XATTR_SD_HASH_SIZE];

	if (DEBUGLEVEL >= 10) {
		DEBUG(10,("fset_nt_acl_xattr: incoming sd for file %s\n",
			  fsp_str_dbg(fsp)));
		NDR_PRINT_DEBUG(security_descriptor,
			discard_const_p(struct security_descriptor, orig_psd));
	}

	status = get_nt_acl_internal(handle, fsp,
			NULL,
			SECINFO_OWNER|SECINFO_GROUP|SECINFO_DACL|SECINFO_SACL,
			&psd);

	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}

	psd->revision = orig_psd->revision;
	/* All our SD's are self relative. */
	psd->type = orig_psd->type | SEC_DESC_SELF_RELATIVE;

	if ((security_info_sent & SECINFO_OWNER) && (orig_psd->owner_sid != NULL)) {
		psd->owner_sid = orig_psd->owner_sid;
	}
	if ((security_info_sent & SECINFO_GROUP) && (orig_psd->group_sid != NULL)) {
		psd->group_sid = orig_psd->group_sid;
	}
	if (security_info_sent & SECINFO_DACL) {
		psd->dacl = orig_psd->dacl;
		psd->type |= SEC_DESC_DACL_PRESENT;
	}
	if (security_info_sent & SECINFO_SACL) {
		psd->sacl = orig_psd->sacl;
		psd->type |= SEC_DESC_SACL_PRESENT;
	}

	status = SMB_VFS_NEXT_FSET_NT_ACL(handle, fsp, security_info_sent, psd);
	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}

	/* Get the full underlying sd, then hash. */
	status = SMB_VFS_NEXT_FGET_NT_ACL(handle,
				fsp,
				HASH_SECURITY_INFO,
				&pdesc_next);

	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}

	status = hash_sd_sha256(pdesc_next, hash);
	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}

	if (DEBUGLEVEL >= 10) {
		DEBUG(10,("fset_nt_acl_xattr: storing xattr sd for file %s\n",
			  fsp_str_dbg(fsp)));
		NDR_PRINT_DEBUG(security_descriptor,
			discard_const_p(struct security_descriptor, psd));
	}
	create_acl_blob(psd, &blob, XATTR_SD_HASH_TYPE_SHA256, hash);
	store_acl_blob_fsp(handle, fsp, &blob);

	return NT_STATUS_OK;
}

static int acl_common_remove_object(vfs_handle_struct *handle,
					const char *path,
					bool is_directory)
{
	connection_struct *conn = handle->conn;
	struct file_id id;
	files_struct *fsp = NULL;
	int ret = 0;
	char *parent_dir = NULL;
	const char *final_component = NULL;
	struct smb_filename local_fname;
	int saved_errno = 0;
	char *saved_dir = NULL;

	saved_dir = vfs_GetWd(talloc_tos(),conn);
	if (!saved_dir) {
		saved_errno = errno;
		goto out;
	}

	if (!parent_dirname(talloc_tos(), path,
			&parent_dir, &final_component)) {
		saved_errno = ENOMEM;
		goto out;
	}

	DEBUG(10,("acl_common_remove_object: removing %s %s/%s\n",
		is_directory ? "directory" : "file",
		parent_dir, final_component ));

 	/* cd into the parent dir to pin it. */
	ret = vfs_ChDir(conn, parent_dir);
	if (ret == -1) {
		saved_errno = errno;
		goto out;
	}

	ZERO_STRUCT(local_fname);
	local_fname.base_name = discard_const_p(char, final_component);

	/* Must use lstat here. */
	ret = SMB_VFS_LSTAT(conn, &local_fname);
	if (ret == -1) {
		saved_errno = errno;
		goto out;
	}

	/* Ensure we have this file open with DELETE access. */
	id = vfs_file_id_from_sbuf(conn, &local_fname.st);
	for (fsp = file_find_di_first(conn->sconn, id); fsp;
		     fsp = file_find_di_next(fsp)) {
		if (fsp->access_mask & DELETE_ACCESS &&
				fsp->delete_on_close) {
			/* We did open this for delete,
			 * allow the delete as root.
			 */
			break;
		}
	}

	if (!fsp) {
		DEBUG(10,("acl_common_remove_object: %s %s/%s "
			"not an open file\n",
			is_directory ? "directory" : "file",
			parent_dir, final_component ));
		saved_errno = EACCES;
		goto out;
	}

	become_root();
	if (is_directory) {
		ret = SMB_VFS_NEXT_RMDIR(handle, final_component);
	} else {
		ret = SMB_VFS_NEXT_UNLINK(handle, &local_fname);
	}
	unbecome_root();

	if (ret == -1) {
		saved_errno = errno;
	}

  out:

	TALLOC_FREE(parent_dir);

	if (saved_dir) {
		vfs_ChDir(conn, saved_dir);
	}
	if (saved_errno) {
		errno = saved_errno;
	}
	return ret;
}

static int rmdir_acl_common(struct vfs_handle_struct *handle,
				const char *path)
{
	int ret;

	ret = SMB_VFS_NEXT_RMDIR(handle, path);
	if (!(ret == -1 && (errno == EACCES || errno == EPERM))) {
		DEBUG(10,("rmdir_acl_common: unlink of %s failed %s\n",
			path,
			strerror(errno) ));
		return ret;
	}

	return acl_common_remove_object(handle,
					path,
					true);
}

static int unlink_acl_common(struct vfs_handle_struct *handle,
			const struct smb_filename *smb_fname)
{
	int ret;

	ret = SMB_VFS_NEXT_UNLINK(handle, smb_fname);
	if (!(ret == -1 && (errno == EACCES || errno == EPERM))) {
		DEBUG(10,("unlink_acl_common: unlink of %s failed %s\n",
			smb_fname->base_name,
			strerror(errno) ));
		return ret;
	}
	/* Don't do anything fancy for streams. */
	if (smb_fname->stream_name) {
		return ret;
	}

	return acl_common_remove_object(handle,
					smb_fname->base_name,
					false);
}

static int chmod_acl_module_common(struct vfs_handle_struct *handle,
			const char *path, mode_t mode)
{
	if (lp_posix_pathnames()) {
		/* Only allow this on POSIX pathnames. */
		return SMB_VFS_NEXT_CHMOD(handle, path, mode);
	}
	return 0;
}

static int fchmod_acl_module_common(struct vfs_handle_struct *handle,
			struct files_struct *fsp, mode_t mode)
{
	if (fsp->posix_open) {
		/* Only allow this on POSIX opens. */
		return SMB_VFS_NEXT_FCHMOD(handle, fsp, mode);
	}
	return 0;
}

static int chmod_acl_acl_module_common(struct vfs_handle_struct *handle,
			const char *name, mode_t mode)
{
	if (lp_posix_pathnames()) {
		/* Only allow this on POSIX pathnames. */
		return SMB_VFS_NEXT_CHMOD_ACL(handle, name, mode);
	}
	return 0;
}

static int fchmod_acl_acl_module_common(struct vfs_handle_struct *handle,
			struct files_struct *fsp, mode_t mode)
{
	if (fsp->posix_open) {
		/* Only allow this on POSIX opens. */
		return SMB_VFS_NEXT_FCHMOD_ACL(handle, fsp, mode);
	}
	return 0;
}