samba-mirror/source3/modules/util_reparse.c

/*
 * Unix SMB/CIFS implementation.
 * Utility functions for reparse points.
 *
 * Copyright (C) Jeremy Allison 2018
 *
 * 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 "includes.h"
#include "util_reparse.h"
#include "libcli/smb/reparse.h"
#include "source3/smbd/proto.h"

static NTSTATUS fsctl_get_reparse_point_reg(struct files_struct *fsp,
					    TALLOC_CTX *ctx,
					    uint8_t **_out_data,
					    uint32_t max_out_len,
					    uint32_t *_out_len)
{
	uint8_t *val = NULL;
	ssize_t sizeret;
	NTSTATUS status;

	/*
	 * 64k+8 bytes is the maximum reparse point length
	 * possible
	 */

	val = talloc_array(ctx, uint8_t, MIN(max_out_len, 65536 + 8));
	if (val == NULL) {
		return NT_STATUS_NO_MEMORY;
	}

	sizeret = SMB_VFS_FGETXATTR(fsp,
				    SAMBA_XATTR_REPARSE_ATTRIB,
				    val,
				    talloc_get_size(val));

	if ((sizeret == -1) && (errno == ERANGE)) {
		status = NT_STATUS_BUFFER_TOO_SMALL;
		goto fail;
	}

	if ((sizeret == -1) && (errno == ENOATTR)) {
		DBG_DEBUG(SAMBA_XATTR_REPARSE_ATTRIB " does not exist\n");
		status = NT_STATUS_NOT_A_REPARSE_POINT;
		goto fail;
	}

	if (sizeret == -1) {
		status = map_nt_error_from_unix(errno);
		DBG_DEBUG("SMB_VFS_FGETXATTR failed: %s\n", strerror(errno));
		goto fail;
	}

	*_out_data = val;
	*_out_len = sizeret;
	return NT_STATUS_OK;
fail:
	TALLOC_FREE(val);
	return status;
}

NTSTATUS fsctl_get_reparse_point(struct files_struct *fsp,
				 TALLOC_CTX *mem_ctx,
				 uint32_t *_reparse_tag,
				 uint8_t **_out_data,
				 uint32_t max_out_len,
				 uint32_t *_out_len)
{
	uint32_t dos_mode;
	uint8_t *out_data = NULL;
	uint32_t out_len = 0;
	uint32_t reparse_tag = 0;
	const uint8_t *reparse_data = NULL;
	size_t reparse_data_length;
	NTSTATUS status = NT_STATUS_NOT_A_REPARSE_POINT;

	dos_mode = fdos_mode(fsp);
	if ((dos_mode & FILE_ATTRIBUTE_REPARSE_POINT) == 0) {
		return NT_STATUS_NOT_A_REPARSE_POINT;
	}

	if (S_ISREG(fsp->fsp_name->st.st_ex_mode)) {
		DBG_DEBUG("%s is a regular file\n", fsp_str_dbg(fsp));
		status = fsctl_get_reparse_point_reg(
			fsp, mem_ctx, &out_data, max_out_len, &out_len);
	}

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

	status = reparse_buffer_check(out_data,
				      out_len,
				      &reparse_tag,
				      &reparse_data,
				      &reparse_data_length);
	if (!NT_STATUS_IS_OK(status)) {
		DBG_DEBUG("Invalid reparse data: %s\n", nt_errstr(status));
		TALLOC_FREE(out_data);
		return status;
	}

	*_reparse_tag = reparse_tag;
	*_out_data = out_data;
	*_out_len = out_len;

	return NT_STATUS_OK;
}

NTSTATUS fsctl_set_reparse_point(struct files_struct *fsp,
				 TALLOC_CTX *mem_ctx,
				 const uint8_t *in_data,
				 uint32_t in_len)
{
	uint32_t reparse_tag;
	const uint8_t *reparse_data = NULL;
	size_t reparse_data_length;
	uint32_t existing_tag;
	uint8_t *existing_data = NULL;
	uint32_t existing_len;
	NTSTATUS status;
	uint32_t dos_mode;
	int ret;

	DBG_DEBUG("Called on %s\n", fsp_str_dbg(fsp));

	if (!S_ISREG(fsp->fsp_name->st.st_ex_mode)) {
		DBG_DEBUG("Can only set reparse point for regular files\n");
		return NT_STATUS_ACCESS_DENIED;
	}

	status = reparse_buffer_check(in_data,
				      in_len,
				      &reparse_tag,
				      &reparse_data,
				      &reparse_data_length);
	if (!NT_STATUS_IS_OK(status)) {
		DBG_DEBUG("check_reparse_data_buffer failed: %s\n",
			  nt_errstr(status));
		return status;
	}

	DBG_DEBUG("reparse tag=%" PRIX32 ", length=%zu\n",
		  reparse_tag,
		  reparse_data_length);

	status = fsctl_get_reparse_point(fsp,
					 talloc_tos(),
					 &existing_tag,
					 &existing_data,
					 UINT32_MAX,
					 &existing_len);
	if (NT_STATUS_IS_OK(status)) {

		TALLOC_FREE(existing_data);

		if (existing_tag != reparse_tag) {
			DBG_DEBUG("Can't overwrite tag %" PRIX32
				  " with tag %" PRIX32 "\n",
				  existing_tag,
				  reparse_tag);
			return NT_STATUS_IO_REPARSE_TAG_MISMATCH;
		}
	}

	/* Store the data */
	ret = SMB_VFS_FSETXATTR(
		fsp, SAMBA_XATTR_REPARSE_ATTRIB, in_data, in_len, 0);
	if (ret == -1) {
		status = map_nt_error_from_unix(errno);
		DBG_DEBUG("setxattr fail on %s - %s\n",
			  fsp_str_dbg(fsp),
			  strerror(errno));
		return status;
	}

	/*
	 * Files with reparse points don't have the ATTR_NORMAL bit
	 * set
	 */
	dos_mode = fdos_mode(fsp);
	dos_mode &= ~FILE_ATTRIBUTE_NORMAL;
	dos_mode |= FILE_ATTRIBUTE_REPARSE_POINT;

	status = SMB_VFS_FSET_DOS_ATTRIBUTES(fsp->conn, fsp, dos_mode);

	if (!NT_STATUS_IS_OK(status)) {
		DBG_ERR("set reparse attr fail on %s - %s\n",
			fsp_str_dbg(fsp),
			nt_errstr(status));
		return status;
	}

	return NT_STATUS_OK;
}

NTSTATUS fsctl_del_reparse_point(struct files_struct *fsp,
				 TALLOC_CTX *mem_ctx,
				 const uint8_t *in_data,
				 uint32_t in_len)
{
	uint32_t existing_tag;
	uint8_t *existing_data = NULL;
	uint32_t existing_len;
	uint32_t reparse_tag;
	const uint8_t *reparse_data = NULL;
	size_t reparse_data_length;
	NTSTATUS status;
	uint32_t dos_mode;
	int ret;

	status = fsctl_get_reparse_point(fsp,
					 talloc_tos(),
					 &existing_tag,
					 &existing_data,
					 UINT32_MAX,
					 &existing_len);
	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}
	TALLOC_FREE(existing_data);

	status = reparse_buffer_check(in_data,
				      in_len,
				      &reparse_tag,
				      &reparse_data,
				      &reparse_data_length);
	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}
	if (reparse_data_length != 0) {
		return NT_STATUS_IO_REPARSE_DATA_INVALID;
	}

	if (existing_tag != reparse_tag) {
		DBG_DEBUG("Expect correct tag %" PRIX32 ", got tag %" PRIX32
			  "\n",
			  existing_tag,
			  reparse_tag);
		return NT_STATUS_IO_REPARSE_TAG_MISMATCH;
	}

	ret = SMB_VFS_FREMOVEXATTR(fsp, SAMBA_XATTR_REPARSE_ATTRIB);
	if (ret == -1) {
		status = map_nt_error_from_unix(errno);
		DBG_DEBUG("removexattr fail on %s - %s\n",
			  fsp_str_dbg(fsp),
			  strerror(errno));
		return status;
	}

	/*
	 * Files with reparse points don't have the ATTR_NORMAL bit
	 * set
	 */
	dos_mode = fdos_mode(fsp);
	dos_mode &= ~FILE_ATTRIBUTE_REPARSE_POINT;

	status = SMB_VFS_FSET_DOS_ATTRIBUTES(fsp->conn, fsp, dos_mode);

	if (!NT_STATUS_IS_OK(status)) {
		DBG_ERR("set reparse attr fail on %s - %s\n",
			fsp_str_dbg(fsp),
			nt_errstr(status));
		return status;
	}

	return NT_STATUS_OK;
}