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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d 
 kernel/fs/overlayfs/export.c
....@@ -1,13 +1,10 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * Overlayfs NFS export support.
34  *
45  * Amir Goldstein <amir73il@gmail.com>
56  *
67  * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
7
- *
8
- * This program is free software; you can redistribute it and/or modify it
9
- * under the terms of the GNU General Public License version 2 as published by
10
- * the Free Software Foundation.
118  */
129 
1310 #include <linux/fs.h>
....@@ -33,7 +30,7 @@
3330 	}
3431 
3532 	if (err) {
36
-		pr_warn_ratelimited("overlayfs: failed to copy up on encode (%pd2, err=%i)\n",
33
+		pr_warn_ratelimited("failed to copy up on encode (%pd2, err=%i)\n",
3734 				    dentry, err);
3835 	}
3936 
....@@ -207,17 +204,18 @@
207204 	 * ovl_connect_layer() will try to make origin's layer "connected" by
208205 	 * copying up a "connectable" ancestor.
209206 	 */
210
-	if (d_is_dir(dentry) && ofs->upper_mnt)
207
+	if (d_is_dir(dentry) && ovl_upper_mnt(ofs))
211208 		return ovl_connect_layer(dentry);
212209 
213210 	/* Lower file handle for indexed and non-upper dir/non-dir */
214211 	return 1;
215212 }
216213 
217
-static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
214
+static int ovl_dentry_to_fid(struct dentry *dentry, u32 *fid, int buflen)
218215 {
219216 	struct ovl_fh *fh = NULL;
220217 	int err, enc_lower;
218
+	int len;
221219 
222220 	/*
223221 	 * Check if we should encode a lower or upper file handle and maybe
....@@ -233,57 +231,45 @@
233231 	if (IS_ERR(fh))
234232 		return PTR_ERR(fh);
235233 
236
-	err = -EOVERFLOW;
237
-	if (fh->len > buflen)
238
-		goto fail;
239
-
240
-	memcpy(buf, (char *)fh, fh->len);
241
-	err = fh->len;
234
+	len = OVL_FH_LEN(fh);
235
+	if (len <= buflen)
236
+		memcpy(fid, fh, len);
237
+	err = len;
242238 
243239 out:
244240 	kfree(fh);
245241 	return err;
246242 
247243 fail:
248
-	pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
249
-			    dentry, err, buflen, fh ? (int)fh->len : 0,
250
-			    fh ? fh->type : 0);
244
+	pr_warn_ratelimited("failed to encode file handle (%pd2, err=%i)\n",
245
+			    dentry, err);
251246 	goto out;
252
-}
253
-
254
-static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len)
255
-{
256
-	int res, len = *max_len << 2;
257
-
258
-	res = ovl_d_to_fh(dentry, (char *)fid, len);
259
-	if (res <= 0)
260
-		return FILEID_INVALID;
261
-
262
-	len = res;
263
-
264
-	/* Round up to dwords */
265
-	*max_len = (len + 3) >> 2;
266
-	return OVL_FILEID;
267247 }
268248 
269249 static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
270250 			 struct inode *parent)
271251 {
272252 	struct dentry *dentry;
273
-	int type;
253
+	int bytes, buflen = *max_len << 2;
274254 
275255 	/* TODO: encode connectable file handles */
276256 	if (parent)
277257 		return FILEID_INVALID;
278258 
279259 	dentry = d_find_any_alias(inode);
280
-	if (WARN_ON(!dentry))
260
+	if (!dentry)
281261 		return FILEID_INVALID;
282262 
283
-	type = ovl_dentry_to_fh(dentry, fid, max_len);
284
-
263
+	bytes = ovl_dentry_to_fid(dentry, fid, buflen);
285264 	dput(dentry);
286
-	return type;
265
+	if (bytes <= 0)
266
+		return FILEID_INVALID;
267
+
268
+	*max_len = bytes >> 2;
269
+	if (bytes > buflen)
270
+		return FILEID_INVALID;
271
+
272
+	return OVL_FILEID_V1;
287273 }
288274 
289275 /*
....@@ -320,29 +306,35 @@
320306 		ovl_set_flag(OVL_UPPERDATA, inode);
321307 
322308 	dentry = d_find_any_alias(inode);
323
-	if (!dentry) {
324
-		dentry = d_alloc_anon(inode->i_sb);
325
-		if (!dentry)
326
-			goto nomem;
327
-		oe = ovl_alloc_entry(lower ? 1 : 0);
328
-		if (!oe)
329
-			goto nomem;
309
+	if (dentry)
310
+		goto out_iput;
330311 
331
-		if (lower) {
332
-			oe->lowerstack->dentry = dget(lower);
333
-			oe->lowerstack->layer = lowerpath->layer;
334
-		}
335
-		dentry->d_fsdata = oe;
336
-		if (upper_alias)
337
-			ovl_dentry_set_upper_alias(dentry);
312
+	dentry = d_alloc_anon(inode->i_sb);
313
+	if (unlikely(!dentry))
314
+		goto nomem;
315
+	oe = ovl_alloc_entry(lower ? 1 : 0);
316
+	if (!oe)
317
+		goto nomem;
318
+
319
+	if (lower) {
320
+		oe->lowerstack->dentry = dget(lower);
321
+		oe->lowerstack->layer = lowerpath->layer;
338322 	}
323
+	dentry->d_fsdata = oe;
324
+	if (upper_alias)
325
+		ovl_dentry_set_upper_alias(dentry);
326
+
327
+	ovl_dentry_update_reval(dentry, upper,
328
+			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
339329 
340330 	return d_instantiate_anon(dentry, inode);
341331 
342332 nomem:
343
-	iput(inode);
344333 	dput(dentry);
345
-	return ERR_PTR(-ENOMEM);
334
+	dentry = ERR_PTR(-ENOMEM);
335
+out_iput:
336
+	iput(inode);
337
+	return dentry;
346338 }
347339 
348340 /* Get the upper or lower dentry in stach whose on layer @idx */
....@@ -370,7 +362,7 @@
370362  */
371363 static struct dentry *ovl_lookup_real_one(struct dentry *connected,
372364 					  struct dentry *real,
373
-					  struct ovl_layer *layer)
365
+					  const struct ovl_layer *layer)
374366 {
375367 	struct inode *dir = d_inode(connected);
376368 	struct dentry *this, *parent = NULL;
....@@ -397,7 +389,8 @@
397389 	 * pointer because we hold no lock on the real dentry.
398390 	 */
399391 	take_dentry_name_snapshot(&name, real);
400
-	this = lookup_one_len(name.name, connected, strlen(name.name));
392
+	this = lookup_one_len(name.name.name, connected, name.name.len);
393
+	release_dentry_name_snapshot(&name);
401394 	err = PTR_ERR(this);
402395 	if (IS_ERR(this)) {
403396 		goto fail;
....@@ -412,13 +405,12 @@
412405 	}
413406 
414407 out:
415
-	release_dentry_name_snapshot(&name);
416408 	dput(parent);
417409 	inode_unlock(dir);
418410 	return this;
419411 
420412 fail:
421
-	pr_warn_ratelimited("overlayfs: failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
413
+	pr_warn_ratelimited("failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
422414 			    real, layer->idx, connected, err);
423415 	this = ERR_PTR(err);
424416 	goto out;
....@@ -426,17 +418,16 @@
426418 
427419 static struct dentry *ovl_lookup_real(struct super_block *sb,
428420 				      struct dentry *real,
429
-				      struct ovl_layer *layer);
421
+				      const struct ovl_layer *layer);
430422 
431423 /*
432424  * Lookup an indexed or hashed overlay dentry by real inode.
433425  */
434426 static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
435427 					    struct dentry *real,
436
-					    struct ovl_layer *layer)
428
+					    const struct ovl_layer *layer)
437429 {
438430 	struct ovl_fs *ofs = sb->s_fs_info;
439
-	struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
440431 	struct dentry *index = NULL;
441432 	struct dentry *this = NULL;
442433 	struct inode *inode;
....@@ -478,7 +469,7 @@
478469 		 * recursive call walks back from indexed upper to the topmost
479470 		 * connected/hashed upper parent (or up to root).
480471 		 */
481
-		this = ovl_lookup_real(sb, upper, &upper_layer);
472
+		this = ovl_lookup_real(sb, upper, &ofs->layers[0]);
482473 		dput(upper);
483474 	}
484475 
....@@ -499,7 +490,7 @@
499490  */
500491 static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
501492 					       struct dentry *real,
502
-					       struct ovl_layer *layer)
493
+					       const struct ovl_layer *layer)
503494 {
504495 	struct dentry *next, *parent = NULL;
505496 	struct dentry *ancestor = ERR_PTR(-EIO);
....@@ -552,7 +543,7 @@
552543  */
553544 static struct dentry *ovl_lookup_real(struct super_block *sb,
554545 				      struct dentry *real,
555
-				      struct ovl_layer *layer)
546
+				      const struct ovl_layer *layer)
556547 {
557548 	struct dentry *connected;
558549 	int err = 0;
....@@ -643,7 +634,7 @@
643634 	return connected;
644635 
645636 fail:
646
-	pr_warn_ratelimited("overlayfs: failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
637
+	pr_warn_ratelimited("failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
647638 			    real, layer->idx, connected, err);
648639 	dput(connected);
649640 	return ERR_PTR(err);
....@@ -658,8 +649,7 @@
658649 				     struct dentry *index)
659650 {
660651 	struct ovl_fs *ofs = sb->s_fs_info;
661
-	struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
662
-	struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer;
652
+	const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;
663653 	struct dentry *real = upper ?: (index ?: lowerpath->dentry);
664654 
665655 	/*
....@@ -687,10 +677,10 @@
687677 	struct dentry *dentry;
688678 	struct dentry *upper;
689679 
690
-	if (!ofs->upper_mnt)
680
+	if (!ovl_upper_mnt(ofs))
691681 		return ERR_PTR(-EACCES);
692682 
693
-	upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
683
+	upper = ovl_decode_real_fh(fh, ovl_upper_mnt(ofs), true);
694684 	if (IS_ERR_OR_NULL(upper))
695685 		return upper;
696686 
....@@ -762,7 +752,7 @@
762752 			goto out_err;
763753 	}
764754 	if (index) {
765
-		err = ovl_verify_origin(index, origin.dentry, false);
755
+		err = ovl_verify_origin(ofs, index, origin.dentry, false);
766756 		if (err)
767757 			goto out_err;
768758 	}
....@@ -780,24 +770,48 @@
780770 	goto out;
781771 }
782772 
773
+static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type)
774
+{
775
+	struct ovl_fh *fh;
776
+
777
+	/* If on-wire inner fid is aligned - nothing to do */
778
+	if (fh_type == OVL_FILEID_V1)
779
+		return (struct ovl_fh *)fid;
780
+
781
+	if (fh_type != OVL_FILEID_V0)
782
+		return ERR_PTR(-EINVAL);
783
+
784
+	if (buflen <= OVL_FH_WIRE_OFFSET)
785
+		return ERR_PTR(-EINVAL);
786
+
787
+	fh = kzalloc(buflen, GFP_KERNEL);
788
+	if (!fh)
789
+		return ERR_PTR(-ENOMEM);
790
+
791
+	/* Copy unaligned inner fh into aligned buffer */
792
+	memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET);
793
+	return fh;
794
+}
795
+
783796 static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
784797 				       int fh_len, int fh_type)
785798 {
786799 	struct dentry *dentry = NULL;
787
-	struct ovl_fh *fh = (struct ovl_fh *) fid;
800
+	struct ovl_fh *fh = NULL;
788801 	int len = fh_len << 2;
789802 	unsigned int flags = 0;
790803 	int err;
791804 
792
-	err = -EINVAL;
793
-	if (fh_type != OVL_FILEID)
805
+	fh = ovl_fid_to_fh(fid, len, fh_type);
806
+	err = PTR_ERR(fh);
807
+	if (IS_ERR(fh))
794808 		goto out_err;
795809 
796810 	err = ovl_check_fh_len(fh, len);
797811 	if (err)
798812 		goto out_err;
799813 
800
-	flags = fh->flags;
814
+	flags = fh->fb.flags;
801815 	dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ?
802816 		 ovl_upper_fh_to_d(sb, fh) :
803817 		 ovl_lower_fh_to_d(sb, fh);
....@@ -805,18 +819,24 @@
805819 	if (IS_ERR(dentry) && err != -ESTALE)
806820 		goto out_err;
807821 
822
+out:
823
+	/* We may have needed to re-align OVL_FILEID_V0 */
824
+	if (!IS_ERR_OR_NULL(fh) && fh != (void *)fid)
825
+		kfree(fh);
826
+
808827 	return dentry;
809828 
810829 out_err:
811
-	pr_warn_ratelimited("overlayfs: failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
812
-			    len, fh_type, flags, err);
813
-	return ERR_PTR(err);
830
+	pr_warn_ratelimited("failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
831
+			    fh_len, fh_type, flags, err);
832
+	dentry = ERR_PTR(err);
833
+	goto out;
814834 }
815835 
816836 static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,
817837 				       int fh_len, int fh_type)
818838 {
819
-	pr_warn_ratelimited("overlayfs: connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
839
+	pr_warn_ratelimited("connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
820840 	return ERR_PTR(-EACCES);
821841 }
822842