1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS
4 * project.
5 *
6 * Copyright (c) 2001-2006 Anton Altaparmakov
7 */
8
9 #include <linux/dcache.h>
10 #include <linux/exportfs.h>
11 #include <linux/security.h>
12 #include <linux/slab.h>
13
14 #include "attrib.h"
15 #include "debug.h"
16 #include "dir.h"
17 #include "mft.h"
18 #include "ntfs.h"
19
20 /**
21 * ntfs_lookup - find the inode represented by a dentry in a directory inode
22 * @dir_ino: directory inode in which to look for the inode
23 * @dent: dentry representing the inode to look for
24 * @flags: lookup flags
25 *
26 * In short, ntfs_lookup() looks for the inode represented by the dentry @dent
27 * in the directory inode @dir_ino and if found attaches the inode to the
28 * dentry @dent.
29 *
30 * In more detail, the dentry @dent specifies which inode to look for by
31 * supplying the name of the inode in @dent->d_name.name. ntfs_lookup()
32 * converts the name to Unicode and walks the contents of the directory inode
33 * @dir_ino looking for the converted Unicode name. If the name is found in the
34 * directory, the corresponding inode is loaded by calling ntfs_iget() on its
35 * inode number and the inode is associated with the dentry @dent via a call to
36 * d_splice_alias().
37 *
38 * If the name is not found in the directory, a NULL inode is inserted into the
39 * dentry @dent via a call to d_add(). The dentry is then termed a negative
40 * dentry.
41 *
42 * Only if an actual error occurs, do we return an error via ERR_PTR().
43 *
44 * In order to handle the case insensitivity issues of NTFS with regards to the
45 * dcache and the dcache requiring only one dentry per directory, we deal with
46 * dentry aliases that only differ in case in ->ntfs_lookup() while maintaining
47 * a case sensitive dcache. This means that we get the full benefit of dcache
48 * speed when the file/directory is looked up with the same case as returned by
49 * ->ntfs_readdir() but that a lookup for any other case (or for the short file
50 * name) will not find anything in dcache and will enter ->ntfs_lookup()
51 * instead, where we search the directory for a fully matching file name
52 * (including case) and if that is not found, we search for a file name that
53 * matches with different case and if that has non-POSIX semantics we return
54 * that. We actually do only one search (case sensitive) and keep tabs on
55 * whether we have found a case insensitive match in the process.
56 *
57 * To simplify matters for us, we do not treat the short vs long filenames as
58 * two hard links but instead if the lookup matches a short filename, we
59 * return the dentry for the corresponding long filename instead.
60 *
61 * There are three cases we need to distinguish here:
62 *
63 * 1) @dent perfectly matches (i.e. including case) a directory entry with a
64 * file name in the WIN32 or POSIX namespaces. In this case
65 * ntfs_lookup_inode_by_name() will return with name set to NULL and we
66 * just d_splice_alias() @dent.
67 * 2) @dent matches (not including case) a directory entry with a file name in
68 * the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return
69 * with name set to point to a kmalloc()ed ntfs_name structure containing
70 * the properly cased little endian Unicode name. We convert the name to the
71 * current NLS code page, search if a dentry with this name already exists
72 * and if so return that instead of @dent. At this point things are
73 * complicated by the possibility of 'disconnected' dentries due to NFS
74 * which we deal with appropriately (see the code comments). The VFS will
75 * then destroy the old @dent and use the one we returned. If a dentry is
76 * not found, we allocate a new one, d_splice_alias() it, and return it as
77 * above.
78 * 3) @dent matches either perfectly or not (i.e. we don't care about case) a
79 * directory entry with a file name in the DOS namespace. In this case
80 * ntfs_lookup_inode_by_name() will return with name set to point to a
81 * kmalloc()ed ntfs_name structure containing the mft reference (cpu endian)
82 * of the inode. We use the mft reference to read the inode and to find the
83 * file name in the WIN32 namespace corresponding to the matched short file
84 * name. We then convert the name to the current NLS code page, and proceed
85 * searching for a dentry with this name, etc, as in case 2), above.
86 *
87 * Locking: Caller must hold i_mutex on the directory.
88 */
89 static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent,
90 unsigned int flags)
91 {
92 ntfs_volume *vol = NTFS_SB(dir_ino->i_sb);
93 struct inode *dent_inode;
94 ntfschar *uname;
95 ntfs_name *name = NULL;
96 MFT_REF mref;
97 unsigned long dent_ino;
98 int uname_len;
99
100 ntfs_debug("Looking up %pd in directory inode 0x%lx.",
101 dent, dir_ino->i_ino);
102 /* Convert the name of the dentry to Unicode. */
103 uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len,
104 &uname);
105 if (uname_len < 0) {
106 if (uname_len != -ENAMETOOLONG)
107 ntfs_error(vol->sb, "Failed to convert name to "
108 "Unicode.");
109 return ERR_PTR(uname_len);
110 }
111 mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len,
112 &name);
113 kmem_cache_free(ntfs_name_cache, uname);
114 if (!IS_ERR_MREF(mref)) {
115 dent_ino = MREF(mref);
116 ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino);
117 dent_inode = ntfs_iget(vol->sb, dent_ino);
118 if (!IS_ERR(dent_inode)) {
119 /* Consistency check. */
120 if (is_bad_inode(dent_inode) || MSEQNO(mref) ==
121 NTFS_I(dent_inode)->seq_no ||
122 dent_ino == FILE_MFT) {
123 /* Perfect WIN32/POSIX match. -- Case 1. */
124 if (!name) {
125 ntfs_debug("Done. (Case 1.)");
126 return d_splice_alias(dent_inode, dent);
127 }
128 /*
129 * We are too indented. Handle imperfect
130 * matches and short file names further below.
131 */
132 goto handle_name;
133 }
134 ntfs_error(vol->sb, "Found stale reference to inode "
135 "0x%lx (reference sequence number = "
136 "0x%x, inode sequence number = 0x%x), "
137 "returning -EIO. Run chkdsk.",
138 dent_ino, MSEQNO(mref),
139 NTFS_I(dent_inode)->seq_no);
140 iput(dent_inode);
141 dent_inode = ERR_PTR(-EIO);
142 } else
143 ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with "
144 "error code %li.", dent_ino,
145 PTR_ERR(dent_inode));
146 kfree(name);
147 /* Return the error code. */
148 return ERR_CAST(dent_inode);
149 }
150 /* It is guaranteed that @name is no longer allocated at this point. */
151 if (MREF_ERR(mref) == -ENOENT) {
152 ntfs_debug("Entry was not found, adding negative dentry.");
153 /* The dcache will handle negative entries. */
154 d_add(dent, NULL);
155 ntfs_debug("Done.");
156 return NULL;
157 }
158 ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error "
159 "code %i.", -MREF_ERR(mref));
160 return ERR_PTR(MREF_ERR(mref));
161 // TODO: Consider moving this lot to a separate function! (AIA)
162 handle_name:
163 {
164 MFT_RECORD *m;
165 ntfs_attr_search_ctx *ctx;
166 ntfs_inode *ni = NTFS_I(dent_inode);
167 int err;
168 struct qstr nls_name;
169
170 nls_name.name = NULL;
171 if (name->type != FILE_NAME_DOS) { /* Case 2. */
172 ntfs_debug("Case 2.");
173 nls_name.len = (unsigned)ntfs_ucstonls(vol,
174 (ntfschar*)&name->name, name->len,
175 (unsigned char**)&nls_name.name, 0);
176 kfree(name);
177 } else /* if (name->type == FILE_NAME_DOS) */ { /* Case 3. */
178 FILE_NAME_ATTR *fn;
179
180 ntfs_debug("Case 3.");
181 kfree(name);
182
183 /* Find the WIN32 name corresponding to the matched DOS name. */
184 ni = NTFS_I(dent_inode);
185 m = map_mft_record(ni);
186 if (IS_ERR(m)) {
187 err = PTR_ERR(m);
188 m = NULL;
189 ctx = NULL;
190 goto err_out;
191 }
192 ctx = ntfs_attr_get_search_ctx(ni, m);
193 if (unlikely(!ctx)) {
194 err = -ENOMEM;
195 goto err_out;
196 }
197 do {
198 ATTR_RECORD *a;
199 u32 val_len;
200
201 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0,
202 NULL, 0, ctx);
203 if (unlikely(err)) {
204 ntfs_error(vol->sb, "Inode corrupt: No WIN32 "
205 "namespace counterpart to DOS "
206 "file name. Run chkdsk.");
207 if (err == -ENOENT)
208 err = -EIO;
209 goto err_out;
210 }
211 /* Consistency checks. */
212 a = ctx->attr;
213 if (a->non_resident || a->flags)
214 goto eio_err_out;
215 val_len = le32_to_cpu(a->data.resident.value_length);
216 if (le16_to_cpu(a->data.resident.value_offset) +
217 val_len > le32_to_cpu(a->length))
218 goto eio_err_out;
219 fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu(
220 ctx->attr->data.resident.value_offset));
221 if ((u32)(fn->file_name_length * sizeof(ntfschar) +
222 sizeof(FILE_NAME_ATTR)) > val_len)
223 goto eio_err_out;
224 } while (fn->file_name_type != FILE_NAME_WIN32);
225
226 /* Convert the found WIN32 name to current NLS code page. */
227 nls_name.len = (unsigned)ntfs_ucstonls(vol,
228 (ntfschar*)&fn->file_name, fn->file_name_length,
229 (unsigned char**)&nls_name.name, 0);
230
231 ntfs_attr_put_search_ctx(ctx);
232 unmap_mft_record(ni);
233 }
234 m = NULL;
235 ctx = NULL;
236
237 /* Check if a conversion error occurred. */
238 if ((signed)nls_name.len < 0) {
239 err = (signed)nls_name.len;
240 goto err_out;
241 }
242 nls_name.hash = full_name_hash(dent, nls_name.name, nls_name.len);
243
244 dent = d_add_ci(dent, dent_inode, &nls_name);
245 kfree(nls_name.name);
246 return dent;
247
248 eio_err_out:
249 ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk.");
250 err = -EIO;
251 err_out:
252 if (ctx)
253 ntfs_attr_put_search_ctx(ctx);
254 if (m)
255 unmap_mft_record(ni);
256 iput(dent_inode);
257 ntfs_error(vol->sb, "Failed, returning error code %i.", err);
258 return ERR_PTR(err);
259 }
260 }
261
262 /**
263 * Inode operations for directories.
264 */
265 const struct inode_operations ntfs_dir_inode_ops = {
266 .lookup = ntfs_lookup, /* VFS: Lookup directory. */
267 };
268
269 /**
270 * ntfs_get_parent - find the dentry of the parent of a given directory dentry
271 * @child_dent: dentry of the directory whose parent directory to find
272 *
273 * Find the dentry for the parent directory of the directory specified by the
274 * dentry @child_dent. This function is called from
275 * fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the
276 * default ->decode_fh() which is export_decode_fh() in the same file.
277 *
278 * The code is based on the ext3 ->get_parent() implementation found in
279 * fs/ext3/namei.c::ext3_get_parent().
280 *
281 * Note: ntfs_get_parent() is called with @d_inode(child_dent)->i_mutex down.
282 *
283 * Return the dentry of the parent directory on success or the error code on
284 * error (IS_ERR() is true).
285 */
286 static struct dentry *ntfs_get_parent(struct dentry *child_dent)
287 {
288 struct inode *vi = d_inode(child_dent);
289 ntfs_inode *ni = NTFS_I(vi);
290 MFT_RECORD *mrec;
291 ntfs_attr_search_ctx *ctx;
292 ATTR_RECORD *attr;
293 FILE_NAME_ATTR *fn;
294 unsigned long parent_ino;
295 int err;
296
297 ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
298 /* Get the mft record of the inode belonging to the child dentry. */
299 mrec = map_mft_record(ni);
300 if (IS_ERR(mrec))
301 return ERR_CAST(mrec);
302 /* Find the first file name attribute in the mft record. */
303 ctx = ntfs_attr_get_search_ctx(ni, mrec);
304 if (unlikely(!ctx)) {
305 unmap_mft_record(ni);
306 return ERR_PTR(-ENOMEM);
307 }
308 try_next:
309 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL,
310 0, ctx);
311 if (unlikely(err)) {
312 ntfs_attr_put_search_ctx(ctx);
313 unmap_mft_record(ni);
314 if (err == -ENOENT)
315 ntfs_error(vi->i_sb, "Inode 0x%lx does not have a "
316 "file name attribute. Run chkdsk.",
317 vi->i_ino);
318 return ERR_PTR(err);
319 }
320 attr = ctx->attr;
321 if (unlikely(attr->non_resident))
322 goto try_next;
323 fn = (FILE_NAME_ATTR *)((u8 *)attr +
324 le16_to_cpu(attr->data.resident.value_offset));
325 if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) >
326 (u8*)attr + le32_to_cpu(attr->length)))
327 goto try_next;
328 /* Get the inode number of the parent directory. */
329 parent_ino = MREF_LE(fn->parent_directory);
330 /* Release the search context and the mft record of the child. */
331 ntfs_attr_put_search_ctx(ctx);
332 unmap_mft_record(ni);
333
334 return d_obtain_alias(ntfs_iget(vi->i_sb, parent_ino));
335 }
336
337 static struct inode *ntfs_nfs_get_inode(struct super_block *sb,
338 u64 ino, u32 generation)
339 {
340 struct inode *inode;
341
342 inode = ntfs_iget(sb, ino);
343 if (!IS_ERR(inode)) {
344 if (is_bad_inode(inode) || inode->i_generation != generation) {
345 iput(inode);
346 inode = ERR_PTR(-ESTALE);
347 }
348 }
349
350 return inode;
351 }
352
353 static struct dentry *ntfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
354 int fh_len, int fh_type)
355 {
356 return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
357 ntfs_nfs_get_inode);
358 }
359
360 static struct dentry *ntfs_fh_to_parent(struct super_block *sb, struct fid *fid,
361 int fh_len, int fh_type)
362 {
363 return generic_fh_to_parent(sb, fid, fh_len, fh_type,
364 ntfs_nfs_get_inode);
365 }
366
367 /**
368 * Export operations allowing NFS exporting of mounted NTFS partitions.
369 *
370 * We use the default ->encode_fh() for now. Note that they
371 * use 32 bits to store the inode number which is an unsigned long so on 64-bit
372 * architectures is usually 64 bits so it would all fail horribly on huge
373 * volumes. I guess we need to define our own encode and decode fh functions
374 * that store 64-bit inode numbers at some point but for now we will ignore the
375 * problem...
376 *
377 * We also use the default ->get_name() helper (used by ->decode_fh() via
378 * fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs
379 * independent.
380 *
381 * The default ->get_parent() just returns -EACCES so we have to provide our
382 * own and the default ->get_dentry() is incompatible with NTFS due to not
383 * allowing the inode number 0 which is used in NTFS for the system file $MFT
384 * and due to using iget() whereas NTFS needs ntfs_iget().
385 */
386 const struct export_operations ntfs_export_ops = {
387 .get_parent = ntfs_get_parent, /* Find the parent of a given
388 directory. */
389 .fh_to_dentry = ntfs_fh_to_dentry,
390 .fh_to_parent = ntfs_fh_to_parent,
391 };