path: root/fs/ntfs3/xattr.c

// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 */

#include <linux/fs.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/xattr.h>

#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"

// clang-format off
#define SYSTEM_DOS_ATTRIB    "system.dos_attrib"
#define SYSTEM_NTFS_ATTRIB   "system.ntfs_attrib"
#define SYSTEM_NTFS_SECURITY "system.ntfs_security"
// clang-format on

static inline size_t unpacked_ea_size(const struct EA_FULL *ea)
{
	return ea->size ? le32_to_cpu(ea->size)
			: ALIGN(struct_size(ea, name,
					    1 + ea->name_len +
						    le16_to_cpu(ea->elength)),
				4);
}

static inline size_t packed_ea_size(const struct EA_FULL *ea)
{
	return struct_size(ea, name,
			   1 + ea->name_len + le16_to_cpu(ea->elength)) -
	       offsetof(struct EA_FULL, flags);
}

/*
 * find_ea
 *
 * Assume there is at least one xattr in the list.
 */
static inline bool find_ea(const struct EA_FULL *ea_all, u32 bytes,
			   const char *name, u8 name_len, u32 *off)
{
	*off = 0;

	if (!ea_all || !bytes)
		return false;

	for (;;) {
		const struct EA_FULL *ea = Add2Ptr(ea_all, *off);
		u32 next_off = *off + unpacked_ea_size(ea);

		if (next_off > bytes)
			return false;

		if (ea->name_len == name_len &&
		    !memcmp(ea->name, name, name_len))
			return true;

		*off = next_off;
		if (next_off >= bytes)
			return false;
	}
}

/*
 * ntfs_read_ea - Read all extended attributes.
 * @ea:		New allocated memory.
 * @info:	Pointer into resident data.
 */
static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea,
			size_t add_bytes, const struct EA_INFO **info)
{
	int err;
	struct ntfs_sb_info *sbi = ni->mi.sbi;
	struct ATTR_LIST_ENTRY *le = NULL;
	struct ATTRIB *attr_info, *attr_ea;
	void *ea_p;
	u32 size;

	static_assert(le32_to_cpu(ATTR_EA_INFO) < le32_to_cpu(ATTR_EA));

	*ea = NULL;
	*info = NULL;

	attr_info =
		ni_find_attr(ni, NULL, &le, ATTR_EA_INFO, NULL, 0, NULL, NULL);
	attr_ea =
		ni_find_attr(ni, attr_info, &le, ATTR_EA, NULL, 0, NULL, NULL);

	if (!attr_ea || !attr_info)
		return 0;

	*info = resident_data_ex(attr_info, sizeof(struct EA_INFO));
	if (!*info)
		return -EINVAL;

	/* Check Ea limit. */
	size = le32_to_cpu((*info)->size);
	if (size > sbi->ea_max_size)
		return -EFBIG;

	if (attr_size(attr_ea) > sbi->ea_max_size)
		return -EFBIG;

	/* Allocate memory for packed Ea. */
	ea_p = kmalloc(size + add_bytes, GFP_NOFS);
	if (!ea_p)
		return -ENOMEM;

	if (!size) {
		;
	} else if (attr_ea->non_res) {
		struct runs_tree run;

		run_init(&run);

		err = attr_load_runs(attr_ea, ni, &run, NULL);
		if (!err)
			err = ntfs_read_run_nb(sbi, &run, 0, ea_p, size, NULL);
		run_close(&run);

		if (err)
			goto out;
	} else {
		void *p = resident_data_ex(attr_ea, size);

		if (!p) {
			err = -EINVAL;
			goto out;
		}
		memcpy(ea_p, p, size);
	}

	memset(Add2Ptr(ea_p, size), 0, add_bytes);
	*ea = ea_p;
	return 0;

out:
	kfree(ea_p);
	*ea = NULL;
	return err;
}

/*
 * ntfs_list_ea
 *
 * Copy a list of xattrs names into the buffer
 * provided, or compute the buffer size required.
 *
 * Return:
 * * Number of bytes used / required on
 * * -ERRNO - on failure
 */
static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
			    size_t bytes_per_buffer)
{
	const struct EA_INFO *info;
	struct EA_FULL *ea_all = NULL;
	const struct EA_FULL *ea;
	u32 off, size;
	int err;
	size_t ret;

	err = ntfs_read_ea(ni, &ea_all, 0, &info);
	if (err)
		return err;

	if (!info || !ea_all)
		return 0;

	size = le32_to_cpu(info->size);

	/* Enumerate all xattrs. */
	for (ret = 0, off = 0; off < size; off += unpacked_ea_size(ea)) {
		ea = Add2Ptr(ea_all, off);

		if (buffer) {
			if (ret + ea->name_len + 1 > bytes_per_buffer) {
				err = -ERANGE;
				goto out;
			}

			memcpy(buffer + ret, ea->name, ea->name_len);
			buffer[ret + ea->name_len] = 0;
		}

		ret += ea->name_len + 1;
	}

out:
	kfree(ea_all);
	return err ? err : ret;
}

static int ntfs_get_ea