1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/nfs/unlink.c
4  *
5  * nfs sillydelete handling
6  *
7  */
8 
9 #include <linux/slab.h>
10 #include <linux/string.h>
11 #include <linux/dcache.h>
12 #include <linux/sunrpc/sched.h>
13 #include <linux/sunrpc/clnt.h>
14 #include <linux/nfs_fs.h>
15 #include <linux/sched.h>
16 #include <linux/wait.h>
17 #include <linux/namei.h>
18 #include <linux/fsnotify.h>
19 
20 #include "internal.h"
21 #include "nfs4_fs.h"
22 #include "iostat.h"
23 #include "delegation.h"
24 
25 #include "nfstrace.h"
26 
27 /**
28  * nfs_free_unlinkdata - release data from a sillydelete operation.
29  * @data: pointer to unlink structure.
30  */
31 static void
nfs_free_unlinkdata(struct nfs_unlinkdata * data)32 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
33 {
34 	put_rpccred(data->cred);
35 	kfree(data->args.name.name);
36 	kfree(data);
37 }
38 
39 /**
40  * nfs_async_unlink_done - Sillydelete post-processing
41  * @task: rpc_task of the sillydelete
42  *
43  * Do the directory attribute update.
44  */
nfs_async_unlink_done(struct rpc_task * task,void * calldata)45 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
46 {
47 	struct nfs_unlinkdata *data = calldata;
48 	struct inode *dir = d_inode(data->dentry->d_parent);
49 
50 	trace_nfs_sillyrename_unlink(data, task->tk_status);
51 	if (!NFS_PROTO(dir)->unlink_done(task, dir))
52 		rpc_restart_call_prepare(task);
53 }
54 
55 /**
56  * nfs_async_unlink_release - Release the sillydelete data.
57  * @task: rpc_task of the sillydelete
58  *
59  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
60  * rpc_task would be freed too.
61  */
nfs_async_unlink_release(void * calldata)62 static void nfs_async_unlink_release(void *calldata)
63 {
64 	struct nfs_unlinkdata	*data = calldata;
65 	struct dentry *dentry = data->dentry;
66 	struct super_block *sb = dentry->d_sb;
67 
68 	up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem);
69 	d_lookup_done(dentry);
70 	nfs_free_unlinkdata(data);
71 	dput(dentry);
72 	nfs_sb_deactive(sb);
73 }
74 
nfs_unlink_prepare(struct rpc_task * task,void * calldata)75 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
76 {
77 	struct nfs_unlinkdata *data = calldata;
78 	struct inode *dir = d_inode(data->dentry->d_parent);
79 	NFS_PROTO(dir)->unlink_rpc_prepare(task, data);
80 }
81 
82 static const struct rpc_call_ops nfs_unlink_ops = {
83 	.rpc_call_done = nfs_async_unlink_done,
84 	.rpc_release = nfs_async_unlink_release,
85 	.rpc_call_prepare = nfs_unlink_prepare,
86 };
87 
nfs_do_call_unlink(struct inode * inode,struct nfs_unlinkdata * data)88 static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data)
89 {
90 	struct rpc_message msg = {
91 		.rpc_argp = &data->args,
92 		.rpc_resp = &data->res,
93 		.rpc_cred = data->cred,
94 	};
95 	struct rpc_task_setup task_setup_data = {
96 		.rpc_message = &msg,
97 		.callback_ops = &nfs_unlink_ops,
98 		.callback_data = data,
99 		.workqueue = nfsiod_workqueue,
100 		.flags = RPC_TASK_ASYNC,
101 	};
102 	struct rpc_task *task;
103 	struct inode *dir = d_inode(data->dentry->d_parent);
104 	nfs_sb_active(dir->i_sb);
105 	data->args.fh = NFS_FH(dir);
106 	nfs_fattr_init(data->res.dir_attr);
107 
108 	NFS_PROTO(dir)->unlink_setup(&msg, data->dentry, inode);
109 
110 	task_setup_data.rpc_client = NFS_CLIENT(dir);
111 	task = rpc_run_task(&task_setup_data);
112 	if (!IS_ERR(task))
113 		rpc_put_task_async(task);
114 }
115 
nfs_call_unlink(struct dentry * dentry,struct inode * inode,struct nfs_unlinkdata * data)116 static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data)
117 {
118 	struct inode *dir = d_inode(dentry->d_parent);
119 	struct dentry *alias;
120 
121 	down_read_non_owner(&NFS_I(dir)->rmdir_sem);
122 	alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
123 	if (IS_ERR(alias)) {
124 		up_read_non_owner(&NFS_I(dir)->rmdir_sem);
125 		return 0;
126 	}
127 	if (!d_in_lookup(alias)) {
128 		int ret;
129 		void *devname_garbage = NULL;
130 
131 		/*
132 		 * Hey, we raced with lookup... See if we need to transfer
133 		 * the sillyrename information to the aliased dentry.
134 		 */
135 		spin_lock(&alias->d_lock);
136 		if (d_really_is_positive(alias) &&
137 		    !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
138 			devname_garbage = alias->d_fsdata;
139 			alias->d_fsdata = data;
140 			alias->d_flags |= DCACHE_NFSFS_RENAMED;
141 			ret = 1;
142 		} else
143 			ret = 0;
144 		spin_unlock(&alias->d_lock);
145 		dput(alias);
146 		up_read_non_owner(&NFS_I(dir)->rmdir_sem);
147 		/*
148 		 * If we'd displaced old cached devname, free it.  At that
149 		 * point dentry is definitely not a root, so we won't need
150 		 * that anymore.
151 		 */
152 		kfree(devname_garbage);
153 		return ret;
154 	}
155 	data->dentry = alias;
156 	nfs_do_call_unlink(inode, data);
157 	return 1;
158 }
159 
160 /**
161  * nfs_async_unlink - asynchronous unlinking of a file
162  * @dir: parent directory of dentry
163  * @dentry: dentry to unlink
164  */
165 static int
nfs_async_unlink(struct dentry * dentry,const struct qstr * name)166 nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
167 {
168 	struct nfs_unlinkdata *data;
169 	int status = -ENOMEM;
170 	void *devname_garbage = NULL;
171 
172 	data = kzalloc(sizeof(*data), GFP_KERNEL);
173 	if (data == NULL)
174 		goto out;
175 	data->args.name.name = kstrdup(name->name, GFP_KERNEL);
176 	if (!data->args.name.name)
177 		goto out_free;
178 	data->args.name.len = name->len;
179 
180 	data->cred = rpc_lookup_cred();
181 	if (IS_ERR(data->cred)) {
182 		status = PTR_ERR(data->cred);
183 		goto out_free_name;
184 	}
185 	data->res.dir_attr = &data->dir_attr;
186 	init_waitqueue_head(&data->wq);
187 
188 	status = -EBUSY;
189 	spin_lock(&dentry->d_lock);
190 	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
191 		goto out_unlock;
192 	dentry->d_flags |= DCACHE_NFSFS_RENAMED;
193 	devname_garbage = dentry->d_fsdata;
194 	dentry->d_fsdata = data;
195 	spin_unlock(&dentry->d_lock);
196 	/*
197 	 * If we'd displaced old cached devname, free it.  At that
198 	 * point dentry is definitely not a root, so we won't need
199 	 * that anymore.
200 	 */
201 	kfree(devname_garbage);
202 	return 0;
203 out_unlock:
204 	spin_unlock(&dentry->d_lock);
205 	put_rpccred(data->cred);
206 out_free_name:
207 	kfree(data->args.name.name);
208 out_free:
209 	kfree(data);
210 out:
211 	return status;
212 }
213 
214 /**
215  * nfs_complete_unlink - Initialize completion of the sillydelete
216  * @dentry: dentry to delete
217  * @inode: inode
218  *
219  * Since we're most likely to be called by dentry_iput(), we
220  * only use the dentry to find the sillydelete. We then copy the name
221  * into the qstr.
222  */
223 void
nfs_complete_unlink(struct dentry * dentry,struct inode * inode)224 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
225 {
226 	struct nfs_unlinkdata	*data;
227 
228 	spin_lock(&dentry->d_lock);
229 	dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
230 	data = dentry->d_fsdata;
231 	dentry->d_fsdata = NULL;
232 	spin_unlock(&dentry->d_lock);
233 
234 	if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data))
235 		nfs_free_unlinkdata(data);
236 }
237 
238 /* Cancel a queued async unlink. Called when a sillyrename run fails. */
239 static void
nfs_cancel_async_unlink(struct dentry * dentry)240 nfs_cancel_async_unlink(struct dentry *dentry)
241 {
242 	spin_lock(&dentry->d_lock);
243 	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
244 		struct nfs_unlinkdata *data = dentry->d_fsdata;
245 
246 		dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
247 		dentry->d_fsdata = NULL;
248 		spin_unlock(&dentry->d_lock);
249 		nfs_free_unlinkdata(data);
250 		return;
251 	}
252 	spin_unlock(&dentry->d_lock);
253 }
254 
255 /**
256  * nfs_async_rename_done - Sillyrename post-processing
257  * @task: rpc_task of the sillyrename
258  * @calldata: nfs_renamedata for the sillyrename
259  *
260  * Do the directory attribute updates and the d_move
261  */
nfs_async_rename_done(struct rpc_task * task,void * calldata)262 static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
263 {
264 	struct nfs_renamedata *data = calldata;
265 	struct inode *old_dir = data->old_dir;
266 	struct inode *new_dir = data->new_dir;
267 	struct dentry *old_dentry = data->old_dentry;
268 
269 	trace_nfs_sillyrename_rename(old_dir, old_dentry,
270 			new_dir, data->new_dentry, task->tk_status);
271 	if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
272 		rpc_restart_call_prepare(task);
273 		return;
274 	}
275 
276 	if (data->complete)
277 		data->complete(task, data);
278 }
279 
280 /**
281  * nfs_async_rename_release - Release the sillyrename data.
282  * @calldata: the struct nfs_renamedata to be released
283  */
nfs_async_rename_release(void * calldata)284 static void nfs_async_rename_release(void *calldata)
285 {
286 	struct nfs_renamedata	*data = calldata;
287 	struct super_block *sb = data->old_dir->i_sb;
288 
289 	if (d_really_is_positive(data->old_dentry))
290 		nfs_mark_for_revalidate(d_inode(data->old_dentry));
291 
292 	/* The result of the rename is unknown. Play it safe by
293 	 * forcing a new lookup */
294 	if (data->cancelled) {
295 		spin_lock(&data->old_dir->i_lock);
296 		nfs_force_lookup_revalidate(data->old_dir);
297 		spin_unlock(&data->old_dir->i_lock);
298 		if (data->new_dir != data->old_dir) {
299 			spin_lock(&data->new_dir->i_lock);
300 			nfs_force_lookup_revalidate(data->new_dir);
301 			spin_unlock(&data->new_dir->i_lock);
302 		}
303 	}
304 
305 	dput(data->old_dentry);
306 	dput(data->new_dentry);
307 	iput(data->old_dir);
308 	iput(data->new_dir);
309 	nfs_sb_deactive(sb);
310 	put_rpccred(data->cred);
311 	kfree(data);
312 }
313 
nfs_rename_prepare(struct rpc_task * task,void * calldata)314 static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
315 {
316 	struct nfs_renamedata *data = calldata;
317 	NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
318 }
319 
320 static const struct rpc_call_ops nfs_rename_ops = {
321 	.rpc_call_done = nfs_async_rename_done,
322 	.rpc_release = nfs_async_rename_release,
323 	.rpc_call_prepare = nfs_rename_prepare,
324 };
325 
326 /**
327  * nfs_async_rename - perform an asynchronous rename operation
328  * @old_dir: directory that currently holds the dentry to be renamed
329  * @new_dir: target directory for the rename
330  * @old_dentry: original dentry to be renamed
331  * @new_dentry: dentry to which the old_dentry should be renamed
332  *
333  * It's expected that valid references to the dentries and inodes are held
334  */
335 struct rpc_task *
nfs_async_rename(struct inode * old_dir,struct inode * new_dir,struct dentry * old_dentry,struct dentry * new_dentry,void (* complete)(struct rpc_task *,struct nfs_renamedata *))336 nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
337 		 struct dentry *old_dentry, struct dentry *new_dentry,
338 		 void (*complete)(struct rpc_task *, struct nfs_renamedata *))
339 {
340 	struct nfs_renamedata *data;
341 	struct rpc_message msg = { };
342 	struct rpc_task_setup task_setup_data = {
343 		.rpc_message = &msg,
344 		.callback_ops = &nfs_rename_ops,
345 		.workqueue = nfsiod_workqueue,
346 		.rpc_client = NFS_CLIENT(old_dir),
347 		.flags = RPC_TASK_ASYNC,
348 	};
349 
350 	data = kzalloc(sizeof(*data), GFP_KERNEL);
351 	if (data == NULL)
352 		return ERR_PTR(-ENOMEM);
353 	task_setup_data.callback_data = data;
354 
355 	data->cred = rpc_lookup_cred();
356 	if (IS_ERR(data->cred)) {
357 		struct rpc_task *task = ERR_CAST(data->cred);
358 		kfree(data);
359 		return task;
360 	}
361 
362 	msg.rpc_argp = &data->args;
363 	msg.rpc_resp = &data->res;
364 	msg.rpc_cred = data->cred;
365 
366 	/* set up nfs_renamedata */
367 	data->old_dir = old_dir;
368 	ihold(old_dir);
369 	data->new_dir = new_dir;
370 	ihold(new_dir);
371 	data->old_dentry = dget(old_dentry);
372 	data->new_dentry = dget(new_dentry);
373 	nfs_fattr_init(&data->old_fattr);
374 	nfs_fattr_init(&data->new_fattr);
375 	data->complete = complete;
376 
377 	/* set up nfs_renameargs */
378 	data->args.old_dir = NFS_FH(old_dir);
379 	data->args.old_name = &old_dentry->d_name;
380 	data->args.new_dir = NFS_FH(new_dir);
381 	data->args.new_name = &new_dentry->d_name;
382 
383 	/* set up nfs_renameres */
384 	data->res.old_fattr = &data->old_fattr;
385 	data->res.new_fattr = &data->new_fattr;
386 
387 	nfs_sb_active(old_dir->i_sb);
388 
389 	NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry);
390 
391 	return rpc_run_task(&task_setup_data);
392 }
393 
394 /*
395  * Perform tasks needed when a sillyrename is done such as cancelling the
396  * queued async unlink if it failed.
397  */
398 static void
nfs_complete_sillyrename(struct rpc_task * task,struct nfs_renamedata * data)399 nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
400 {
401 	struct dentry *dentry = data->old_dentry;
402 
403 	if (task->tk_status != 0) {
404 		nfs_cancel_async_unlink(dentry);
405 		return;
406 	}
407 
408 	/*
409 	 * vfs_unlink and the like do not issue this when a file is
410 	 * sillyrenamed, so do it here.
411 	 */
412 	fsnotify_nameremove(dentry, 0);
413 }
414 
415 #define SILLYNAME_PREFIX ".nfs"
416 #define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1)
417 #define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1)
418 #define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1)
419 #define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \
420 		SILLYNAME_FILEID_LEN + \
421 		SILLYNAME_COUNTER_LEN)
422 
423 /**
424  * nfs_sillyrename - Perform a silly-rename of a dentry
425  * @dir: inode of directory that contains dentry
426  * @dentry: dentry to be sillyrenamed
427  *
428  * NFSv2/3 is stateless and the server doesn't know when the client is
429  * holding a file open. To prevent application problems when a file is
430  * unlinked while it's still open, the client performs a "silly-rename".
431  * That is, it renames the file to a hidden file in the same directory,
432  * and only performs the unlink once the last reference to it is put.
433  *
434  * The final cleanup is done during dentry_iput.
435  *
436  * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
437  * could take responsibility for keeping open files referenced.  The server
438  * would also need to ensure that opened-but-deleted files were kept over
439  * reboots.  However, we may not assume a server does so.  (RFC 5661
440  * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
441  * use to advertise that it does this; some day we may take advantage of
442  * it.))
443  */
444 int
nfs_sillyrename(struct inode * dir,struct dentry * dentry)445 nfs_sillyrename(struct inode *dir, struct dentry *dentry)
446 {
447 	static unsigned int sillycounter;
448 	unsigned char silly[SILLYNAME_LEN + 1];
449 	unsigned long long fileid;
450 	struct dentry *sdentry;
451 	struct inode *inode = d_inode(dentry);
452 	struct rpc_task *task;
453 	int            error = -EBUSY;
454 
455 	dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n",
456 		dentry, d_count(dentry));
457 	nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
458 
459 	/*
460 	 * We don't allow a dentry to be silly-renamed twice.
461 	 */
462 	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
463 		goto out;
464 
465 	fileid = NFS_FILEID(d_inode(dentry));
466 
467 	sdentry = NULL;
468 	do {
469 		int slen;
470 		dput(sdentry);
471 		sillycounter++;
472 		slen = scnprintf(silly, sizeof(silly),
473 				SILLYNAME_PREFIX "%0*llx%0*x",
474 				SILLYNAME_FILEID_LEN, fileid,
475 				SILLYNAME_COUNTER_LEN, sillycounter);
476 
477 		dfprintk(VFS, "NFS: trying to rename %pd to %s\n",
478 				dentry, silly);
479 
480 		sdentry = lookup_one_len(silly, dentry->d_parent, slen);
481 		/*
482 		 * N.B. Better to return EBUSY here ... it could be
483 		 * dangerous to delete the file while it's in use.
484 		 */
485 		if (IS_ERR(sdentry))
486 			goto out;
487 	} while (d_inode(sdentry) != NULL); /* need negative lookup */
488 
489 	ihold(inode);
490 
491 	/* queue unlink first. Can't do this from rpc_release as it
492 	 * has to allocate memory
493 	 */
494 	error = nfs_async_unlink(dentry, &sdentry->d_name);
495 	if (error)
496 		goto out_dput;
497 
498 	/* run the rename task, undo unlink if it fails */
499 	task = nfs_async_rename(dir, dir, dentry, sdentry,
500 					nfs_complete_sillyrename);
501 	if (IS_ERR(task)) {
502 		error = -EBUSY;
503 		nfs_cancel_async_unlink(dentry);
504 		goto out_dput;
505 	}
506 
507 	/* wait for the RPC task to complete, unless a SIGKILL intervenes */
508 	error = rpc_wait_for_completion_task(task);
509 	if (error == 0)
510 		error = task->tk_status;
511 	switch (error) {
512 	case 0:
513 		/* The rename succeeded */
514 		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
515 		spin_lock(&inode->i_lock);
516 		NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
517 		NFS_I(inode)->cache_validity |= NFS_INO_INVALID_CHANGE
518 			| NFS_INO_INVALID_CTIME
519 			| NFS_INO_REVAL_FORCED;
520 		spin_unlock(&inode->i_lock);
521 		d_move(dentry, sdentry);
522 		break;
523 	case -ERESTARTSYS:
524 		/* The result of the rename is unknown. Play it safe by
525 		 * forcing a new lookup */
526 		d_drop(dentry);
527 		d_drop(sdentry);
528 	}
529 	rpc_put_task(task);
530 out_dput:
531 	iput(inode);
532 	dput(sdentry);
533 out:
534 	return error;
535 }
536