1 // SPDX-License-Identifier: GPL-2.0
2 
3 /*
4  * Directory operations for Coda filesystem
5  * Original version: (C) 1996 P. Braam and M. Callahan
6  * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
7  *
8  * Carnegie Mellon encourages users to contribute improvements to
9  * the Coda project. Contact Peter Braam (coda@cs.cmu.edu).
10  */
11 
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/time.h>
15 #include <linux/fs.h>
16 #include <linux/slab.h>
17 #include <linux/file.h>
18 #include <linux/stat.h>
19 #include <linux/errno.h>
20 #include <linux/string.h>
21 #include <linux/spinlock.h>
22 #include <linux/namei.h>
23 #include <linux/uaccess.h>
24 
25 #include <linux/coda.h>
26 #include <linux/coda_psdev.h>
27 #include "coda_linux.h"
28 #include "coda_cache.h"
29 
30 #include "coda_int.h"
31 
32 /* same as fs/bad_inode.c */
coda_return_EIO(void)33 static int coda_return_EIO(void)
34 {
35 	return -EIO;
36 }
37 #define CODA_EIO_ERROR ((void *) (coda_return_EIO))
38 
39 /* inode operations for directories */
40 /* access routines: lookup, readlink, permission */
coda_lookup(struct inode * dir,struct dentry * entry,unsigned int flags)41 static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, unsigned int flags)
42 {
43 	struct super_block *sb = dir->i_sb;
44 	const char *name = entry->d_name.name;
45 	size_t length = entry->d_name.len;
46 	struct inode *inode;
47 	int type = 0;
48 
49 	if (length > CODA_MAXNAMLEN) {
50 		pr_err("name too long: lookup, %s (%*s)\n",
51 		       coda_i2s(dir), (int)length, name);
52 		return ERR_PTR(-ENAMETOOLONG);
53 	}
54 
55 	/* control object, create inode on the fly */
56 	if (is_root_inode(dir) && coda_iscontrol(name, length)) {
57 		inode = coda_cnode_makectl(sb);
58 		type = CODA_NOCACHE;
59 	} else {
60 		struct CodaFid fid = { { 0, } };
61 		int error = venus_lookup(sb, coda_i2f(dir), name, length,
62 				     &type, &fid);
63 		inode = !error ? coda_cnode_make(&fid, sb) : ERR_PTR(error);
64 	}
65 
66 	if (!IS_ERR(inode) && (type & CODA_NOCACHE))
67 		coda_flag_inode(inode, C_VATTR | C_PURGE);
68 
69 	if (inode == ERR_PTR(-ENOENT))
70 		inode = NULL;
71 
72 	return d_splice_alias(inode, entry);
73 }
74 
75 
coda_permission(struct inode * inode,int mask)76 int coda_permission(struct inode *inode, int mask)
77 {
78 	int error;
79 
80 	if (mask & MAY_NOT_BLOCK)
81 		return -ECHILD;
82 
83 	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
84 
85 	if (!mask)
86 		return 0;
87 
88 	if ((mask & MAY_EXEC) && !execute_ok(inode))
89 		return -EACCES;
90 
91 	if (coda_cache_check(inode, mask))
92 		return 0;
93 
94 	error = venus_access(inode->i_sb, coda_i2f(inode), mask);
95 
96 	if (!error)
97 		coda_cache_enter(inode, mask);
98 
99 	return error;
100 }
101 
102 
coda_dir_update_mtime(struct inode * dir)103 static inline void coda_dir_update_mtime(struct inode *dir)
104 {
105 #ifdef REQUERY_VENUS_FOR_MTIME
106 	/* invalidate the directory cnode's attributes so we refetch the
107 	 * attributes from venus next time the inode is referenced */
108 	coda_flag_inode(dir, C_VATTR);
109 #else
110 	/* optimistically we can also act as if our nose bleeds. The
111 	 * granularity of the mtime is coarse anyways so we might actually be
112 	 * right most of the time. Note: we only do this for directories. */
113 	dir->i_mtime = dir->i_ctime = current_time(dir);
114 #endif
115 }
116 
117 /* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
118  * trick to fool GNU find's optimizations. If we can't be sure of the link
119  * (because of volume mount points) we set i_nlink to 1 which forces find
120  * to consider every child as a possible directory. We should also never
121  * see an increment or decrement for deleted directories where i_nlink == 0 */
coda_dir_inc_nlink(struct inode * dir)122 static inline void coda_dir_inc_nlink(struct inode *dir)
123 {
124 	if (dir->i_nlink >= 2)
125 		inc_nlink(dir);
126 }
127 
coda_dir_drop_nlink(struct inode * dir)128 static inline void coda_dir_drop_nlink(struct inode *dir)
129 {
130 	if (dir->i_nlink > 2)
131 		drop_nlink(dir);
132 }
133 
134 /* creation routines: create, mknod, mkdir, link, symlink */
coda_create(struct inode * dir,struct dentry * de,umode_t mode,bool excl)135 static int coda_create(struct inode *dir, struct dentry *de, umode_t mode, bool excl)
136 {
137 	int error;
138 	const char *name=de->d_name.name;
139 	int length=de->d_name.len;
140 	struct inode *inode;
141 	struct CodaFid newfid;
142 	struct coda_vattr attrs;
143 
144 	if (is_root_inode(dir) && coda_iscontrol(name, length))
145 		return -EPERM;
146 
147 	error = venus_create(dir->i_sb, coda_i2f(dir), name, length,
148 				0, mode, &newfid, &attrs);
149 	if (error)
150 		goto err_out;
151 
152 	inode = coda_iget(dir->i_sb, &newfid, &attrs);
153 	if (IS_ERR(inode)) {
154 		error = PTR_ERR(inode);
155 		goto err_out;
156 	}
157 
158 	/* invalidate the directory cnode's attributes */
159 	coda_dir_update_mtime(dir);
160 	d_instantiate(de, inode);
161 	return 0;
162 err_out:
163 	d_drop(de);
164 	return error;
165 }
166 
coda_mkdir(struct inode * dir,struct dentry * de,umode_t mode)167 static int coda_mkdir(struct inode *dir, struct dentry *de, umode_t mode)
168 {
169 	struct inode *inode;
170 	struct coda_vattr attrs;
171 	const char *name = de->d_name.name;
172 	int len = de->d_name.len;
173 	int error;
174 	struct CodaFid newfid;
175 
176 	if (is_root_inode(dir) && coda_iscontrol(name, len))
177 		return -EPERM;
178 
179 	attrs.va_mode = mode;
180 	error = venus_mkdir(dir->i_sb, coda_i2f(dir),
181 			       name, len, &newfid, &attrs);
182 	if (error)
183 		goto err_out;
184 
185 	inode = coda_iget(dir->i_sb, &newfid, &attrs);
186 	if (IS_ERR(inode)) {
187 		error = PTR_ERR(inode);
188 		goto err_out;
189 	}
190 
191 	/* invalidate the directory cnode's attributes */
192 	coda_dir_inc_nlink(dir);
193 	coda_dir_update_mtime(dir);
194 	d_instantiate(de, inode);
195 	return 0;
196 err_out:
197 	d_drop(de);
198 	return error;
199 }
200 
201 /* try to make de an entry in dir_inodde linked to source_de */
coda_link(struct dentry * source_de,struct inode * dir_inode,struct dentry * de)202 static int coda_link(struct dentry *source_de, struct inode *dir_inode,
203 	  struct dentry *de)
204 {
205 	struct inode *inode = d_inode(source_de);
206         const char * name = de->d_name.name;
207 	int len = de->d_name.len;
208 	int error;
209 
210 	if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
211 		return -EPERM;
212 
213 	error = venus_link(dir_inode->i_sb, coda_i2f(inode),
214 			   coda_i2f(dir_inode), (const char *)name, len);
215 	if (error) {
216 		d_drop(de);
217 		return error;
218 	}
219 
220 	coda_dir_update_mtime(dir_inode);
221 	ihold(inode);
222 	d_instantiate(de, inode);
223 	inc_nlink(inode);
224 	return 0;
225 }
226 
227 
coda_symlink(struct inode * dir_inode,struct dentry * de,const char * symname)228 static int coda_symlink(struct inode *dir_inode, struct dentry *de,
229 			const char *symname)
230 {
231 	const char *name = de->d_name.name;
232 	int len = de->d_name.len;
233 	int symlen;
234 	int error;
235 
236 	if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
237 		return -EPERM;
238 
239 	symlen = strlen(symname);
240 	if (symlen > CODA_MAXPATHLEN)
241 		return -ENAMETOOLONG;
242 
243 	/*
244 	 * This entry is now negative. Since we do not create
245 	 * an inode for the entry we have to drop it.
246 	 */
247 	d_drop(de);
248 	error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
249 			      symname, symlen);
250 
251 	/* mtime is no good anymore */
252 	if (!error)
253 		coda_dir_update_mtime(dir_inode);
254 
255 	return error;
256 }
257 
258 /* destruction routines: unlink, rmdir */
coda_unlink(struct inode * dir,struct dentry * de)259 static int coda_unlink(struct inode *dir, struct dentry *de)
260 {
261         int error;
262 	const char *name = de->d_name.name;
263 	int len = de->d_name.len;
264 
265 	error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
266 	if (error)
267 		return error;
268 
269 	coda_dir_update_mtime(dir);
270 	drop_nlink(d_inode(de));
271 	return 0;
272 }
273 
coda_rmdir(struct inode * dir,struct dentry * de)274 static int coda_rmdir(struct inode *dir, struct dentry *de)
275 {
276 	const char *name = de->d_name.name;
277 	int len = de->d_name.len;
278 	int error;
279 
280 	error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
281 	if (!error) {
282 		/* VFS may delete the child */
283 		if (d_really_is_positive(de))
284 			clear_nlink(d_inode(de));
285 
286 		/* fix the link count of the parent */
287 		coda_dir_drop_nlink(dir);
288 		coda_dir_update_mtime(dir);
289 	}
290 	return error;
291 }
292 
293 /* rename */
coda_rename(struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)294 static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
295 		       struct inode *new_dir, struct dentry *new_dentry,
296 		       unsigned int flags)
297 {
298 	const char *old_name = old_dentry->d_name.name;
299 	const char *new_name = new_dentry->d_name.name;
300 	int old_length = old_dentry->d_name.len;
301 	int new_length = new_dentry->d_name.len;
302 	int error;
303 
304 	if (flags)
305 		return -EINVAL;
306 
307 	error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
308 			     coda_i2f(new_dir), old_length, new_length,
309 			     (const char *) old_name, (const char *)new_name);
310 	if (!error) {
311 		if (d_really_is_positive(new_dentry)) {
312 			if (d_is_dir(new_dentry)) {
313 				coda_dir_drop_nlink(old_dir);
314 				coda_dir_inc_nlink(new_dir);
315 			}
316 			coda_dir_update_mtime(old_dir);
317 			coda_dir_update_mtime(new_dir);
318 			coda_flag_inode(d_inode(new_dentry), C_VATTR);
319 		} else {
320 			coda_flag_inode(old_dir, C_VATTR);
321 			coda_flag_inode(new_dir, C_VATTR);
322 		}
323 	}
324 	return error;
325 }
326 
CDT2DT(unsigned char cdt)327 static inline unsigned int CDT2DT(unsigned char cdt)
328 {
329 	unsigned int dt;
330 
331 	switch(cdt) {
332 	case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
333 	case CDT_FIFO:	  dt = DT_FIFO;    break;
334 	case CDT_CHR:	  dt = DT_CHR;     break;
335 	case CDT_DIR:	  dt = DT_DIR;     break;
336 	case CDT_BLK:	  dt = DT_BLK;     break;
337 	case CDT_REG:	  dt = DT_REG;     break;
338 	case CDT_LNK:	  dt = DT_LNK;     break;
339 	case CDT_SOCK:	  dt = DT_SOCK;    break;
340 	case CDT_WHT:	  dt = DT_WHT;     break;
341 	default:	  dt = DT_UNKNOWN; break;
342 	}
343 	return dt;
344 }
345 
346 /* support routines */
coda_venus_readdir(struct file * coda_file,struct dir_context * ctx)347 static int coda_venus_readdir(struct file *coda_file, struct dir_context *ctx)
348 {
349 	struct coda_file_info *cfi;
350 	struct coda_inode_info *cii;
351 	struct file *host_file;
352 	struct venus_dirent *vdir;
353 	unsigned long vdir_size = offsetof(struct venus_dirent, d_name);
354 	unsigned int type;
355 	struct qstr name;
356 	ino_t ino;
357 	int ret;
358 
359 	cfi = CODA_FTOC(coda_file);
360 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
361 	host_file = cfi->cfi_container;
362 
363 	cii = ITOC(file_inode(coda_file));
364 
365 	vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
366 	if (!vdir) return -ENOMEM;
367 
368 	if (!dir_emit_dots(coda_file, ctx))
369 		goto out;
370 
371 	while (1) {
372 		loff_t pos = ctx->pos - 2;
373 
374 		/* read entries from the directory file */
375 		ret = kernel_read(host_file, vdir, sizeof(*vdir), &pos);
376 		if (ret < 0) {
377 			pr_err("%s: read dir %s failed %d\n",
378 			       __func__, coda_f2s(&cii->c_fid), ret);
379 			break;
380 		}
381 		if (ret == 0) break; /* end of directory file reached */
382 
383 		/* catch truncated reads */
384 		if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
385 			pr_err("%s: short read on %s\n",
386 			       __func__, coda_f2s(&cii->c_fid));
387 			ret = -EBADF;
388 			break;
389 		}
390 		/* validate whether the directory file actually makes sense */
391 		if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
392 			pr_err("%s: invalid dir %s\n",
393 			       __func__, coda_f2s(&cii->c_fid));
394 			ret = -EBADF;
395 			break;
396 		}
397 
398 		name.len = vdir->d_namlen;
399 		name.name = vdir->d_name;
400 
401 		/* Make sure we skip '.' and '..', we already got those */
402 		if (name.name[0] == '.' && (name.len == 1 ||
403 		    (name.name[1] == '.' && name.len == 2)))
404 			vdir->d_fileno = name.len = 0;
405 
406 		/* skip null entries */
407 		if (vdir->d_fileno && name.len) {
408 			ino = vdir->d_fileno;
409 			type = CDT2DT(vdir->d_type);
410 			if (!dir_emit(ctx, name.name, name.len, ino, type))
411 				break;
412 		}
413 		/* we'll always have progress because d_reclen is unsigned and
414 		 * we've already established it is non-zero. */
415 		ctx->pos += vdir->d_reclen;
416 	}
417 out:
418 	kfree(vdir);
419 	return 0;
420 }
421 
422 /* file operations for directories */
coda_readdir(struct file * coda_file,struct dir_context * ctx)423 static int coda_readdir(struct file *coda_file, struct dir_context *ctx)
424 {
425 	struct coda_file_info *cfi;
426 	struct file *host_file;
427 	int ret;
428 
429 	cfi = CODA_FTOC(coda_file);
430 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
431 	host_file = cfi->cfi_container;
432 
433 	if (host_file->f_op->iterate || host_file->f_op->iterate_shared) {
434 		struct inode *host_inode = file_inode(host_file);
435 		ret = -ENOENT;
436 		if (!IS_DEADDIR(host_inode)) {
437 			if (host_file->f_op->iterate_shared) {
438 				inode_lock_shared(host_inode);
439 				ret = host_file->f_op->iterate_shared(host_file, ctx);
440 				file_accessed(host_file);
441 				inode_unlock_shared(host_inode);
442 			} else {
443 				inode_lock(host_inode);
444 				ret = host_file->f_op->iterate(host_file, ctx);
445 				file_accessed(host_file);
446 				inode_unlock(host_inode);
447 			}
448 		}
449 		return ret;
450 	}
451 	/* Venus: we must read Venus dirents from a file */
452 	return coda_venus_readdir(coda_file, ctx);
453 }
454 
455 /* called when a cache lookup succeeds */
coda_dentry_revalidate(struct dentry * de,unsigned int flags)456 static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
457 {
458 	struct inode *inode;
459 	struct coda_inode_info *cii;
460 
461 	if (flags & LOOKUP_RCU)
462 		return -ECHILD;
463 
464 	inode = d_inode(de);
465 	if (!inode || is_root_inode(inode))
466 		goto out;
467 	if (is_bad_inode(inode))
468 		goto bad;
469 
470 	cii = ITOC(d_inode(de));
471 	if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
472 		goto out;
473 
474 	shrink_dcache_parent(de);
475 
476 	/* propagate for a flush */
477 	if (cii->c_flags & C_FLUSH)
478 		coda_flag_inode_children(inode, C_FLUSH);
479 
480 	if (d_count(de) > 1)
481 		/* pretend it's valid, but don't change the flags */
482 		goto out;
483 
484 	/* clear the flags. */
485 	spin_lock(&cii->c_lock);
486 	cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
487 	spin_unlock(&cii->c_lock);
488 bad:
489 	return 0;
490 out:
491 	return 1;
492 }
493 
494 /*
495  * This is the callback from dput() when d_count is going to 0.
496  * We use this to unhash dentries with bad inodes.
497  */
coda_dentry_delete(const struct dentry * dentry)498 static int coda_dentry_delete(const struct dentry * dentry)
499 {
500 	int flags;
501 
502 	if (d_really_is_negative(dentry))
503 		return 0;
504 
505 	flags = (ITOC(d_inode(dentry))->c_flags) & C_PURGE;
506 	if (is_bad_inode(d_inode(dentry)) || flags) {
507 		return 1;
508 	}
509 	return 0;
510 }
511 
512 
513 
514 /*
515  * This is called when we want to check if the inode has
516  * changed on the server.  Coda makes this easy since the
517  * cache manager Venus issues a downcall to the kernel when this
518  * happens
519  */
coda_revalidate_inode(struct inode * inode)520 int coda_revalidate_inode(struct inode *inode)
521 {
522 	struct coda_vattr attr;
523 	int error;
524 	int old_mode;
525 	ino_t old_ino;
526 	struct coda_inode_info *cii = ITOC(inode);
527 
528 	if (!cii->c_flags)
529 		return 0;
530 
531 	if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
532 		error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
533 		if (error)
534 			return -EIO;
535 
536 		/* this inode may be lost if:
537 		   - it's ino changed
538 		   - type changes must be permitted for repair and
539 		   missing mount points.
540 		*/
541 		old_mode = inode->i_mode;
542 		old_ino = inode->i_ino;
543 		coda_vattr_to_iattr(inode, &attr);
544 
545 		if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
546 			pr_warn("inode %ld, fid %s changed type!\n",
547 				inode->i_ino, coda_f2s(&(cii->c_fid)));
548 		}
549 
550 		/* the following can happen when a local fid is replaced
551 		   with a global one, here we lose and declare the inode bad */
552 		if (inode->i_ino != old_ino)
553 			return -EIO;
554 
555 		coda_flag_inode_children(inode, C_FLUSH);
556 
557 		spin_lock(&cii->c_lock);
558 		cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
559 		spin_unlock(&cii->c_lock);
560 	}
561 	return 0;
562 }
563 
564 const struct dentry_operations coda_dentry_operations = {
565 	.d_revalidate	= coda_dentry_revalidate,
566 	.d_delete	= coda_dentry_delete,
567 };
568 
569 const struct inode_operations coda_dir_inode_operations = {
570 	.create		= coda_create,
571 	.lookup		= coda_lookup,
572 	.link		= coda_link,
573 	.unlink		= coda_unlink,
574 	.symlink	= coda_symlink,
575 	.mkdir		= coda_mkdir,
576 	.rmdir		= coda_rmdir,
577 	.mknod		= CODA_EIO_ERROR,
578 	.rename		= coda_rename,
579 	.permission	= coda_permission,
580 	.getattr	= coda_getattr,
581 	.setattr	= coda_setattr,
582 };
583 
584 const struct file_operations coda_dir_operations = {
585 	.llseek		= generic_file_llseek,
586 	.read		= generic_read_dir,
587 	.iterate	= coda_readdir,
588 	.open		= coda_open,
589 	.release	= coda_release,
590 	.fsync		= coda_fsync,
591 };
592