x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 747 insertions, 0 deletions

diff --git a/fs/ntfs3/dir.c b/fs/ntfs3/dir.c
new file mode 100644
index 000000000..eb9152e9f
--- /dev/null
+++ b/fs/ntfs3/dir.c
@@ -0,0 +1,747 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
+ *
+ *  Directory handling functions for NTFS-based filesystems.
+ *
+ */
+
+#include <linux/fs.h>
+#include <linux/filelock.h>
+#include <linux/nls.h>
+
+#include "debug.h"
+#include "ntfs.h"
+#include "ntfs_fs.h"
+
+/* Convert little endian UTF-16 to NLS string. */
+int ntfs_utf16_to_nls(struct ntfs_sb_info *sbi, const __le16 *name, u32 len,
+		      u8 *buf, int buf_len)
+{
+	int ret, warn;
+	u8 *op;
+	struct nls_table *nls = sbi->options->nls;
+
+	static_assert(sizeof(wchar_t) == sizeof(__le16));
+
+	if (buf_len <= 0)
+		return -EINVAL;
+
+	buf_len -= 1;
+
+	if (!nls) {
+		/* UTF-16 -> UTF-8 */
+		ret = utf16s_to_utf8s((wchar_t *)name, len, UTF16_LITTLE_ENDIAN,
+				      buf, buf_len);
+		buf[ret] = '\0';
+		return ret;
+	}
+
+	op = buf;
+	warn = 0;
+
+	while (len--) {
+		u16 ec;
+		int charlen;
+		char dump[5];
+
+		if (buf_len < NLS_MAX_CHARSET_SIZE) {
+			ntfs_warn(sbi->sb,
+				  "filename was truncated while converting.");
+			break;
+		}
+
+		ec = le16_to_cpu(*name++);
+		charlen = nls->uni2char(ec, op, buf_len);
+
+		if (charlen > 0) {
+			op += charlen;
+			buf_len -= charlen;
+			continue;
+		}
+
+		*op++ = '_';
+		buf_len -= 1;
+		if (warn)
+			continue;
+
+		warn = 1;
+		hex_byte_pack(&dump[0], ec >> 8);
+		hex_byte_pack(&dump[2], ec);
+		dump[4] = 0;
+
+		ntfs_err(sbi->sb, "failed to convert \"%s\" to %s", dump,
+			 nls->charset);
+	}
+
+	*op = '\0';
+	return op - buf;
+}
+
+// clang-format off
+#define PLANE_SIZE	0x00010000
+
+#define SURROGATE_PAIR	0x0000d800
+#define SURROGATE_LOW	0x00000400
+#define SURROGATE_BITS	0x000003ff
+// clang-format on
+
+/*
+ * put_utf16 - Modified version of put_utf16 from fs/nls/nls_base.c
+ *
+ * Function is sparse warnings free.
+ */
+static inline void put_utf16(wchar_t *s, unsigned int c,
+			     enum utf16_endian endian)
+{
+	static_assert(sizeof(wchar_t) == sizeof(__le16));
+	static_assert(sizeof(wchar_t) == sizeof(__be16));
+
+	switch (endian) {
+	default:
+		*s = (wchar_t)c;
+		break;
+	case UTF16_LITTLE_ENDIAN:
+		*(__le16 *)s = __cpu_to_le16(c);
+		break;
+	case UTF16_BIG_ENDIAN:
+		*(__be16 *)s = __cpu_to_be16(c);
+		break;
+	}
+}
+
+/*
+ * _utf8s_to_utf16s
+ *
+ * Modified version of 'utf8s_to_utf16s' allows to
+ * detect -ENAMETOOLONG without writing out of expected maximum.
+ */
+static int _utf8s_to_utf16s(const u8 *s, int inlen, enum utf16_endian endian,
+			    wchar_t *pwcs, int maxout)
+{
+	u16 *op;
+	int size;
+	unicode_t u;
+
+	op = pwcs;
+	while (inlen > 0 && *s) {
+		if (*s & 0x80) {
+			size = utf8_to_utf32(s, inlen, &u);
+			if (size < 0)
+				return -EINVAL;
+			s += size;
+			inlen -= size;
+
+			if (u >= PLANE_SIZE) {
+				if (maxout < 2)
+					return -ENAMETOOLONG;
+
+				u -= PLANE_SIZE;
+				put_utf16(op++,
+					  SURROGATE_PAIR |
+						  ((u >> 10) & SURROGATE_BITS),
+					  endian);
+				put_utf16(op++,
+					  SURROGATE_PAIR | SURROGATE_LOW |
+						  (u & SURROGATE_BITS),
+					  endian);
+				maxout -= 2;
+			} else {
+				if (maxout < 1)
+					return -ENAMETOOLONG;
+
+				put_utf16(op++, u, endian);
+				maxout--;
+			}
+		} else {
+			if (maxout < 1)
+				return -ENAMETOOLONG;
+
+			put_utf16(op++, *s++, endian);
+			inlen--;
+			maxout--;
+		}
+	}
+	return op - pwcs;
+}
+
+/*
+ * ntfs_nls_to_utf16 - Convert input string to UTF-16.
+ * @name:	Input name.
+ * @name_len:	Input name length.
+ * @uni:	Destination memory.
+ * @max_ulen:	Destination memory.
+ * @endian:	Endian of target UTF-16 string.
+ *
+ * This function is called:
+ * - to create NTFS name
+ * - to create symlink
+ *
+ * Return: UTF-16 string length or error (if negative).
+ */
+int ntfs_nls_to_utf16(struct ntfs_sb_info *sbi, const u8 *name, u32 name_len,
+		      struct cpu_str *uni, u32 max_ulen,
+		      enum utf16_endian endian)
+{
+	int ret, slen, i;
+	const u8 *end;
+	struct nls_table *nls = sbi->options->nls;
+	u16 *uname = uni->name;
+
+	static_assert(sizeof(wchar_t) == sizeof(u16));
+
+	if (!nls) {
+		/* utf8 -> utf16 */
+		ret = _utf8s_to_utf16s(name, name_len, endian, uname, max_ulen);
+	} else {
+		for (ret = 0, end = name + name_len; name < end;
+		     ret++, name += slen) {
+			if (ret >= max_ulen)
+				return -ENAMETOOLONG;
+
+			slen = nls->char2uni(name, end - name, uname + ret);
+			if (!slen)
+				return -EINVAL;
+			if (slen < 0)
+				return slen;
+		}
+
+#ifdef __BIG_ENDIAN
+		if (endian == UTF16_LITTLE_ENDIAN) {
+			i = ret;
+
+			while (i--) {
+				__cpu_to_le16s(uname);
+				uname++;
+			}
+		}
+#else
+		if (endian == UTF16_BIG_ENDIAN) {
+			i = ret;
+
+			while (i--) {
+				__cpu_to_be16s(uname);
+				uname++;
+			}
+		}
+#endif
+	}
+
+	uni->len = ret;
+	uni->ads_len = 0;
+	if (ret > 0 && sbi->options->ads) {
+		uname = uni->name;
+		/* Find delimiter in range [1 : ret-2). */
+		for (i = 1; i + 1 < ret; i++) {
+			if (uname[i] == ':') {
+				uni->ads_len = ret - i - 1;
+				uni->len = i;
+				uname[i] = 0;
+				ret = i;
+
+				uname += i + 1;
+				i = uni->ads_len;
+				/* Return ADS name as little endian. Always */
+#ifdef __BIG_ENDIAN
+				if (endian == UTF16_LITTLE_ENDIAN) {
+					while (i--) {
+						__cpu_to_le16s(uname);
+						uname++;
+					}
+				}
+#else
+				if (endian == UTF16_BIG_ENDIAN) {
+					while (i--) {
+						__cpu_to_be16s(uname);
+						uname++;
+					}
+				}
+#endif
+				break;
+			}
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * dir_search_u - Helper function.
+ */
+struct inode *dir_search_flags(struct inode *dir, const struct cpu_str *uni,
+			       struct ntfs_fnd *fnd, u32 flags)
+{
+	int err = 0;
+	struct super_block *sb = dir->i_sb;
+	struct ntfs_sb_info *sbi = sb->s_fs_info;
+	struct ntfs_inode *ni = ntfs_i(dir);
+	struct NTFS_DE *e;
+	int diff;
+	struct inode *inode = NULL;
+	struct ntfs_fnd *fnd_a = NULL;
+
+	if (!fnd) {
+		fnd_a = fnd_get();
+		if (!fnd_a) {
+			err = -ENOMEM;
+			goto out;
+		}
+		fnd = fnd_a;
+	}
+
+	err = indx_find(&ni->dir, ni, NULL, uni, 0, sbi, &diff, &e, fnd);
+
+	if (err)
+		goto out;
+
+	if (diff) {
+		err = -ENOENT;
+		goto out;
+	}
+
+	inode = ntfs_iget5_flags(sb, &e->ref, uni, flags);
+	if (!IS_ERR(inode) && is_bad_inode(inode)) {
+		iput(inode);
+		err = -EINVAL;
+	}
+out:
+	fnd_put(fnd_a);
+
+	return err == -ENOENT ? NULL : err ? ERR_PTR(err) : inode;
+}
+
+static inline bool de_fname_fits(const struct NTFS_DE *e, u32 e_size,
+				 const struct ATTR_FILE_NAME *fname)
+{
+	return sizeof(struct NTFS_DE) + fname_full_size(fname) <= e_size;
+}
+
+/*
+ * returns false if 'ctx' if full
+ */
+static inline bool ntfs_dir_emit(struct ntfs_sb_info *sbi,
+				 struct ntfs_inode *ni, const struct NTFS_DE *e,
+				 u8 *name, struct dir_context *ctx)
+{
+	const struct ATTR_FILE_NAME *fname;
+	u64 ino;
+	int name_len;
+	u32 dt_type;
+
+	fname = Add2Ptr(e, sizeof(struct NTFS_DE));
+
+	if (fname->type == FILE_NAME_DOS)
+		return true;
+
+	if (!mi_is_ref(&ni->mi, &fname->home))
+		return true;
+
+	ino = ino_get(&e->ref);
+
+	if (ino == MFT_REC_ROOT)
+		return true;
+
+	/* Skip meta files. Unless option to show metafiles is set. */
+	if (!sbi->options->showmeta && ntfs_is_meta_file(sbi, ino))
+		return true;
+
+	if (sbi->options->nohidden && (fname->dup.fa & FILE_ATTRIBUTE_HIDDEN))
+		return true;
+
+	if (!de_fname_fits(e, le16_to_cpu(e->size), fname))
+		return true;
+
+	name_len = ntfs_utf16_to_nls(sbi, fname->name, fname->name_len, name,
+				     PATH_MAX);
+	if (name_len <= 0) {
+		ntfs_warn(sbi->sb, "failed to convert name for inode %llx.",
+			  ino);
+		return true;
+	}
+
+	/*
+	 * NTFS: symlinks are "dir + reparse" or "file + reparse"
+	 * Unfortunately reparse attribute is used for many purposes (several dozens).
+	 * It is not possible here to know is this name symlink or not.
+	 * To get exactly the type of name we should to open inode (read mft).
+	 * getattr for opened file (fstat) correctly returns symlink.
+	 */
+	dt_type = (fname->dup.fa & FILE_ATTRIBUTE_DIRECTORY) ? DT_DIR : DT_REG;
+
+	/*
+	 * It is not reliable to detect the type of name using duplicated information
+	 * stored in parent directory.
+	 * The only correct way to get the type of name - read MFT record and find ATTR_STD.
+	 * The code below is not good idea.
+	 * It does additional locks/reads just to get the type of name.
+	 * Should we use additional mount option to enable branch below?
+	 */
+	if (fname->dup.extend_data && ino != ni->mi.rno) {
+		struct inode *inode = ntfs_iget5(sbi->sb, &e->ref, NULL);
+		if (!IS_ERR_OR_NULL(inode)) {
+			dt_type = fs_umode_to_dtype(inode->i_mode);
+			iput(inode);
+		}
+	}
+
+	return dir_emit(ctx, (s8 *)name, name_len, ino, dt_type);
+}
+
+/*
+ * ntfs_read_hdr - Helper function for ntfs_readdir().
+ *
+ * returns 0 if ok.
+ * returns -EINVAL if directory is corrupted.
+ * returns +1 if 'ctx' is full.
+ */
+static int ntfs_read_hdr(struct ntfs_sb_info *sbi, struct ntfs_inode *ni,
+			 const struct INDEX_HDR *hdr, u64 vbo, u64 pos,
+			 u8 *name, struct dir_context *ctx)
+{
+	const struct NTFS_DE *e;
+	u32 e_size;
+	u32 end = le32_to_cpu(hdr->used);
+	u32 off = le32_to_cpu(hdr->de_off);
+
+	for (;; off += e_size) {
+		if (off + sizeof(struct NTFS_DE) > end)
+			return -EINVAL;
+
+		e = Add2Ptr(hdr, off);
+		e_size = le16_to_cpu(e->size);
+		if (e_size < sizeof(struct NTFS_DE) || off + e_size > end)
+			return -EINVAL;
+
+		if (de_is_last(e))
+			return 0;
+
+		/* Skip already enumerated. */
+		if (vbo + off < pos)
+			continue;
+
+		if (le16_to_cpu(e->key_size) < SIZEOF_ATTRIBUTE_FILENAME)
+			return -EINVAL;
+
+		ctx->pos = vbo + off;
+
+		/* Submit the name to the filldir callback. */
+		if (!ntfs_dir_emit(sbi, ni, e, name, ctx)) {
+			/* ctx is full. */
+			return +1;
+		}
+	}
+}
+
+/*
+ * ntfs_readdir - file_operations::iterate_shared
+ *
+ * Use non sorted enumeration.
+ * Sorted enumeration may result infinite loop if names tree contains loop.
+ */
+static int ntfs_readdir(struct file *file, struct dir_context *ctx)
+{
+	const struct INDEX_ROOT *root;
+	size_t bit;
+	int err = 0;
+	struct inode *dir = file_inode(file);
+	struct ntfs_inode *ni = ntfs_i(dir);
+	struct super_block *sb = dir->i_sb;
+	struct ntfs_sb_info *sbi = sb->s_fs_info;
+	loff_t i_size = i_size_read(dir);
+	u64 pos = ctx->pos;
+	u8 *name = NULL;
+	struct indx_node *node = NULL;
+	u8 index_bits = ni->dir.index_bits;
+	size_t max_bit = i_size >> ni->dir.index_bits;
+	loff_t eod = i_size + sbi->record_size;
+
+	/* Name is a buffer of PATH_MAX length. */
+	static_assert(NTFS_NAME_LEN * 4 < PATH_MAX);
+
+	if (!pos) {
+		/*
+		 * ni->dir.version increments each directory change.
+		 * Save the initial value of ni->dir.version.
+		 */
+		file->private_data = (void *)ni->dir.version;
+	}
+
+	if (pos >= eod) {
+		if (file->private_data == (void *)ni->dir.version) {
+			/* No changes since first readdir. */
+			return 0;
+		}
+
+		/*
+		 * Handle directories that changed after the initial readdir().
+		 *
+		 * Some user space code implements recursive removal like this instead
+		 * of calling rmdir(2) directly:
+		 *
+		 *      fd = opendir(path);
+		 *      while ((dent = readdir(fd)))
+		 *              unlinkat(dirfd(fd), dent->d_name, 0);
+		 *      closedir(fd);
+		 *
+		 * POSIX leaves unspecified what readdir() should return once the
+		 * directory has been modified after opendir()/rewinddir(), so this
+		 * pattern is not guaranteed to work on all filesystems or platforms.
+		 *
+		 * In ntfs3 the internal name tree may be reshaped while entries are
+		 * being removed, so there is no stable anchor for continuing a
+		 * single-pass walk based on the original readdir() order.
+		 *
+		 * In practice some widely used tools (for example certain rm(1)
+		 * implementations) have used this readdir()/unlink() loop, and some
+		 * filesystems behave in a way that effectively makes it work in the
+		 * common case.
+		 *
+		 * The code below follows that practice and tries to provide
+		 * "rmdir-like" behaviour for such callers on ntfs3, even though the
+		 * situation is not strictly defined by the APIs.
+		 *
+		 * Apple documents the same readdir()/unlink() issue and a workaround
+		 * for HFS file systems in:
+		 * https://web.archive.org/web/20220122122948/https:/support.apple.com/kb/TA21420?locale=en_US
+		 */
+		ctx->pos = pos = 3;
+		file->private_data = (void *)ni->dir.version;
+	}
+
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+
+	name = kmalloc(PATH_MAX, GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	if (!ni->mi_loaded && ni->attr_list.size) {
+		/*
+		 * Directory inode is locked for read.
+		 * Load all subrecords to avoid 'write' access to 'ni' during
+		 * directory reading.
+		 */
+		ni_lock(ni);
+		if (!ni->mi_loaded && ni->attr_list.size) {
+			err = ni_load_all_mi(ni);
+			if (!err)
+				ni->mi_loaded = true;
+		}
+		ni_unlock(ni);
+		if (err)
+			goto out;
+	}
+
+	/*
+	 * Keep directory metadata stable for the whole walk. Loading subrecords
+	 * once is not enough if concurrent writeback can still compact ATTR_LIST
+	 * entries and free the record that ntfs_read_hdr() is currently walking.
+	 */
+	ni_lock(ni);
+
+	root = indx_get_root(&ni->dir, ni, NULL, NULL);
+	if (!root) {
+		err = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (pos >= sbi->record_size) {
+		bit = (pos - sbi->record_size) >> index_bits;
+	} else {
+		/*
+		 * Add each name from root in 'ctx'.
+		 */
+		err = ntfs_read_hdr(sbi, ni, &root->ihdr, 0, pos, name, ctx);
+		if (err)
+			goto out_unlock;
+		bit = 0;
+	}
+
+	/*
+	 * Enumerate indexes until the end of dir.
+	 */
+	for (; bit < max_bit; bit += 1) {
+		/* Get the next used index. */
+		err = indx_used_bit(&ni->dir, ni, &bit);
+		if (err)
+			goto out_unlock;
+
+		if (bit == MINUS_ONE_T) {
+			/* no more used indexes. end of dir. */
+			break;
+		}
+
+		if (bit >= max_bit) {
+			/* Corrupted directory. */
+			err = -EINVAL;
+			goto out_unlock;
+		}
+
+		err = indx_read_ra(&ni->dir, ni, bit << ni->dir.idx2vbn_bits,
+				   &node, &file->f_ra);
+		if (err)
+			goto out_unlock;
+
+		/*
+		 * Add each name from index in 'ctx'.
+		 */
+		err = ntfs_read_hdr(sbi, ni, &node->index->ihdr,
+				    ((u64)bit << index_bits) + sbi->record_size,
+				    pos, name, ctx);
+		if (err)
+			goto out_unlock;
+	}
+
+out_unlock:
+	ni_unlock(ni);
+
+out:
+	kfree(name);
+	put_indx_node(node);
+
+	if (!err) {
+		/* End of directory. */
+		ctx->pos = eod;
+	} else if (err == 1) {
+		/* 'ctx' is full. */
+		err = 0;
+	} else if (err == -ENOENT) {
+		err = 0;
+		ctx->pos = pos;
+	} else if (err < 0) {
+		if (err == -EINVAL)
+			_ntfs_bad_inode(dir);
+		ctx->pos = eod;
+	}
+
+	return err;
+}
+
+/*
+ * Return fname when @e passes the same checks as ntfs_dir_emit() before
+ * exposing an entry (valid key, non-DOS, fname fits in e->size).
+ */
+static inline const struct ATTR_FILE_NAME *
+de_countable_fname(const struct NTFS_DE *e, u32 e_size)
+{
+	const struct ATTR_FILE_NAME *fname;
+
+	fname = de_get_fname(e);
+	if (!fname || fname->type == FILE_NAME_DOS ||
+	    !de_fname_fits(e, e_size, fname))
+		return NULL;
+
+	return fname;
+}
+
+static int ntfs_dir_count(struct inode *dir, bool *is_empty, size_t *dirs,
+			  size_t *files)
+{
+	int err = 0;
+	struct ntfs_inode *ni = ntfs_i(dir);
+	struct NTFS_DE *e = NULL;
+	struct INDEX_ROOT *root;
+	struct INDEX_HDR *hdr;
+	const struct ATTR_FILE_NAME *fname;
+	u32 e_size, off, end;
+	size_t drs = 0, fles = 0, bit = 0;
+	struct indx_node *node = NULL;
+	size_t max_indx = i_size_read(&ni->vfs_inode) >> ni->dir.index_bits;
+
+	if (is_empty)
+		*is_empty = true;
+
+	root = indx_get_root(&ni->dir, ni, NULL, NULL);
+	if (!root)
+		return -EINVAL;
+
+	hdr = &root->ihdr;
+
+	for (;;) {
+		end = le32_to_cpu(hdr->used);
+		off = le32_to_cpu(hdr->de_off);
+
+		for (; off + sizeof(struct NTFS_DE) <= end; off += e_size) {
+			e = Add2Ptr(hdr, off);
+			e_size = le16_to_cpu(e->size);
+			if (e_size < sizeof(struct NTFS_DE) ||
+			    off + e_size > end) {
+				/* Looks like corruption. */
+				break;
+			}
+
+			if (de_is_last(e))
+				break;
+
+			fname = de_countable_fname(e, e_size);
+			if (!fname)
+				continue;
+
+			if (is_empty) {
+				*is_empty = false;
+				if (!dirs && !files)
+					goto out;
+			}
+
+			if (fname->dup.fa & FILE_ATTRIBUTE_DIRECTORY)
+				drs += 1;
+			else
+				fles += 1;
+		}
+
+		if (bit >= max_indx)
+			goto out;
+
+		err = indx_used_bit(&ni->dir, ni, &bit);
+		if (err)
+			goto out;
+
+		if (bit == MINUS_ONE_T)
+			goto out;
+
+		if (bit >= max_indx)
+			goto out;
+
+		err = indx_read(&ni->dir, ni, bit << ni->dir.idx2vbn_bits,
+				&node);
+		if (err)
+			goto out;
+
+		hdr = &node->index->ihdr;
+		bit += 1;
+	}
+
+out:
+	put_indx_node(node);
+	if (dirs)
+		*dirs = drs;
+	if (files)
+		*files = fles;
+
+	return err;
+}
+
+bool dir_is_empty(struct inode *dir)
+{
+	bool is_empty = false;
+
+	ntfs_dir_count(dir, &is_empty, NULL, NULL);
+
+	return is_empty;
+}
+
+// clang-format off
+const struct file_operations ntfs_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= ntfs_readdir,
+	.fsync		= ntfs_file_fsync,
+	.open		= ntfs_file_open,
+	.unlocked_ioctl = ntfs_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl   = ntfs_compat_ioctl,
+#endif
+	.setlease	= generic_setlease,
+};
+// clang-format on