debug lk

hc

2024-02-20 e636c8d336489bf3eed5878299e6cc045bbad077

 kernel/fs/overlayfs/dir.c
..
..
@@ -1,10 +1,7 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
1
2
 /*
2
3
  *
3
4
  * Copyright (C) 2011 Novell Inc.
4
- *
5
- * This program is free software; you can redistribute it and/or modify it
6
- * under the terms of the GNU General Public License version 2 as published by
7
- * the Free Software Foundation.
8
5
  */
9
6
 
10
7
 #include <linux/fs.h>
..
..
@@ -21,7 +18,7 @@
21
18
 
22
19
 static unsigned short ovl_redirect_max = 256;
23
20
 module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
24
-MODULE_PARM_DESC(ovl_redirect_max,
21
+MODULE_PARM_DESC(redirect_max,
25
22
 		 "Maximum length of absolute redirect xattr value");
26
23
 
27
24
 static int ovl_set_redirect(struct dentry *dentry, bool samedir);
..
..
@@ -38,14 +35,14 @@
38
35
 	dput(wdentry);
39
36
 
40
37
 	if (err) {
41
-		pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
38
+		pr_err("cleanup of '%pd2' failed (%i)\n",
42
39
 		       wdentry, err);
43
40
 	}
44
41
 
45
42
 	return err;
46
43
 }
47
44
 
48
-static struct dentry *ovl_lookup_temp(struct dentry *workdir)
45
+struct dentry *ovl_lookup_temp(struct dentry *workdir)
49
46
 {
50
47
 	struct dentry *temp;
51
48
 	char name[20];
..
..
@@ -56,7 +53,7 @@
56
53
 
57
54
 	temp = lookup_one_len(name, workdir, strlen(name));
58
55
 	if (!IS_ERR(temp) && temp->d_inode) {
59
-		pr_err("overlayfs: workdir/%s already exists\n", name);
56
+		pr_err("workdir/%s already exists\n", name);
60
57
 		dput(temp);
61
58
 		temp = ERR_PTR(-EIO);
62
59
 	}
..
..
@@ -65,35 +62,59 @@
65
62
 }
66
63
 
67
64
 /* caller holds i_mutex on workdir */
68
-static struct dentry *ovl_whiteout(struct dentry *workdir)
65
+static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
69
66
 {
70
67
 	int err;
71
68
 	struct dentry *whiteout;
69
+	struct dentry *workdir = ofs->workdir;
72
70
 	struct inode *wdir = workdir->d_inode;
73
71
 
74
-	whiteout = ovl_lookup_temp(workdir);
75
-	if (IS_ERR(whiteout))
76
-		return whiteout;
72
+	if (!ofs->whiteout) {
73
+		whiteout = ovl_lookup_temp(workdir);
74
+		if (IS_ERR(whiteout))
75
+			goto out;
77
76
 
78
-	err = ovl_do_whiteout(wdir, whiteout);
79
-	if (err) {
80
-		dput(whiteout);
81
-		whiteout = ERR_PTR(err);
77
+		err = ovl_do_whiteout(wdir, whiteout);
78
+		if (err) {
79
+			dput(whiteout);
80
+			whiteout = ERR_PTR(err);
81
+			goto out;
82
+		}
83
+		ofs->whiteout = whiteout;
82
84
 	}
83
85
 
86
+	if (ofs->share_whiteout) {
87
+		whiteout = ovl_lookup_temp(workdir);
88
+		if (IS_ERR(whiteout))
89
+			goto out;
90
+
91
+		err = ovl_do_link(ofs->whiteout, wdir, whiteout);
92
+		if (!err)
93
+			goto out;
94
+
95
+		if (err != -EMLINK) {
96
+			pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n",
97
+				ofs->whiteout->d_inode->i_nlink, err);
98
+			ofs->share_whiteout = false;
99
+		}
100
+		dput(whiteout);
101
+	}
102
+	whiteout = ofs->whiteout;
103
+	ofs->whiteout = NULL;
104
+out:
84
105
 	return whiteout;
85
106
 }
86
107
 
87
108
 /* Caller must hold i_mutex on both workdir and dir */
88
-int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
109
+int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir,
89
110
 			     struct dentry *dentry)
90
111
 {
91
-	struct inode *wdir = workdir->d_inode;
112
+	struct inode *wdir = ofs->workdir->d_inode;
92
113
 	struct dentry *whiteout;
93
114
 	int err;
94
115
 	int flags = 0;
95
116
 
96
-	whiteout = ovl_whiteout(workdir);
117
+	whiteout = ovl_whiteout(ofs);
97
118
 	err = PTR_ERR(whiteout);
98
119
 	if (IS_ERR(whiteout))
99
120
 		return err;
..
..
@@ -136,7 +157,7 @@
136
157
 	d = lookup_one_len(dentry->d_name.name, dentry->d_parent,
137
158
 			   dentry->d_name.len);
138
159
 	if (IS_ERR(d)) {
139
-		pr_warn("overlayfs: failed lookup after mkdir (%pd2, err=%i).\n",
160
+		pr_warn("failed lookup after mkdir (%pd2, err=%i).\n",
140
161
 			dentry, err);
141
162
 		return PTR_ERR(d);
142
163
 	}
..
..
@@ -245,6 +266,8 @@
245
266
 
246
267
 	ovl_dir_modified(dentry->d_parent, false);
247
268
 	ovl_dentry_set_upper_alias(dentry);
269
+	ovl_dentry_init_reval(dentry, newdentry);
270
+
248
271
 	if (!hardlink) {
249
272
 		/*
250
273
 		 * ovl_obtain_alias() can be called after ovl_create_real()
..
..
@@ -261,6 +284,8 @@
261
284
 		inode = ovl_get_inode(dentry->d_sb, &oip);
262
285
 		if (IS_ERR(inode))
263
286
 			return PTR_ERR(inode);
287
+		if (inode == oip.newinode)
288
+			ovl_set_flag(OVL_UPPERDATA, inode);
264
289
 	} else {
265
290
 		WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
266
291
 		dput(newdentry);
..
..
@@ -269,7 +294,7 @@
269
294
 
270
295
 	d_instantiate(dentry, inode);
271
296
 	if (inode != oip.newinode) {
272
-		pr_warn_ratelimited("overlayfs: newly created inode found in cache (%pd2)\n",
297
+		pr_warn_ratelimited("newly created inode found in cache (%pd2)\n",
273
298
 				    dentry);
274
299
 	}
275
300
 
..
..
@@ -367,7 +392,7 @@
367
392
 	if (IS_ERR(opaquedir))
368
393
 		goto out_unlock;
369
394
 
370
-	err = ovl_copy_xattr(upper, opaquedir);
395
+	err = ovl_copy_xattr(dentry->d_sb, upper, opaquedir);
371
396
 	if (err)
372
397
 		goto out_cleanup;
373
398
 
..
..
@@ -413,13 +438,12 @@
413
438
 	if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
414
439
 		return 0;
415
440
 
416
-	size = posix_acl_to_xattr(NULL, acl, NULL, 0);
441
+	size = posix_acl_xattr_size(acl->a_count);
417
442
 	buffer = kmalloc(size, GFP_KERNEL);
418
443
 	if (!buffer)
419
444
 		return -ENOMEM;
420
445
 
421
-	size = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
422
-	err = size;
446
+	err = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
423
447
 	if (err < 0)
424
448
 		goto out_free;
425
449
 
..
..
@@ -561,31 +585,45 @@
561
585
 			goto out_revert_creds;
562
586
 	}
563
587
 
564
-	err = -ENOMEM;
565
-	override_cred = prepare_creds();
566
-	if (override_cred) {
588
+	if (!attr->hardlink) {
589
+		err = -ENOMEM;
590
+		override_cred = prepare_creds();
591
+		if (!override_cred)
592
+			goto out_revert_creds;
593
+		/*
594
+		 * In the creation cases(create, mkdir, mknod, symlink),
595
+		 * ovl should transfer current's fs{u,g}id to underlying
596
+		 * fs. Because underlying fs want to initialize its new
597
+		 * inode owner using current's fs{u,g}id. And in this
598
+		 * case, the @inode is a new inode that is initialized
599
+		 * in inode_init_owner() to current's fs{u,g}id. So use
600
+		 * the inode's i_{u,g}id to override the cred's fs{u,g}id.
601
+		 *
602
+		 * But in the other hardlink case, ovl_link() does not
603
+		 * create a new inode, so just use the ovl mounter's
604
+		 * fs{u,g}id.
605
+		 */
567
606
 		override_cred->fsuid = inode->i_uid;
568
607
 		override_cred->fsgid = inode->i_gid;
569
-		if (!attr->hardlink) {
570
-			err = security_dentry_create_files_as(dentry,
571
-					attr->mode, &dentry->d_name,
572
-					old_cred ? old_cred : current_cred(),
573
-					override_cred);
574
-			if (err) {
575
-				put_cred(override_cred);
576
-				goto out_revert_creds;
577
-			}
608
+		err = security_dentry_create_files_as(dentry,
609
+				attr->mode, &dentry->d_name,
610
+				old_cred ? old_cred : current_cred(),
611
+				override_cred);
612
+		if (err) {
613
+			put_cred(override_cred);
614
+			goto out_revert_creds;
578
615
 		}
579
616
 		hold_cred = override_creds(override_cred);
580
617
 		put_cred(override_cred);
581
-
582
-		if (!ovl_dentry_is_whiteout(dentry))
583
-			err = ovl_create_upper(dentry, inode, attr);
584
-		else
585
-			err = ovl_create_over_whiteout(dentry, inode, attr);
586
618
 	}
619
+
620
+	if (!ovl_dentry_is_whiteout(dentry))
621
+		err = ovl_create_upper(dentry, inode, attr);
622
+	else
623
+		err = ovl_create_over_whiteout(dentry, inode, attr);
624
+
587
625
 out_revert_creds:
588
-	ovl_revert_creds(old_cred ?: hold_cred);
626
+	ovl_revert_creds(dentry->d_sb, old_cred ?: hold_cred);
589
627
 	if (old_cred && hold_cred)
590
628
 		put_cred(hold_cred);
591
629
 	return err;
..
..
@@ -663,7 +701,7 @@
663
701
 
664
702
 	old_cred = ovl_override_creds(dentry->d_sb);
665
703
 	err = ovl_set_redirect(dentry, false);
666
-	ovl_revert_creds(old_cred);
704
+	ovl_revert_creds(dentry->d_sb, old_cred);
667
705
 
668
706
 	return err;
669
707
 }
..
..
@@ -672,7 +710,6 @@
672
710
 		    struct dentry *new)
673
711
 {
674
712
 	int err;
675
-	bool locked = false;
676
713
 	struct inode *inode;
677
714
 
678
715
 	err = ovl_want_write(old);
..
..
@@ -693,7 +730,7 @@
693
730
 			goto out_drop_write;
694
731
 	}
695
732
 
696
-	err = ovl_nlink_start(old, &locked);
733
+	err = ovl_nlink_start(old);
697
734
 	if (err)
698
735
 		goto out_drop_write;
699
736
 
..
..
@@ -706,7 +743,7 @@
706
743
 	if (err)
707
744
 		iput(inode);
708
745
 
709
-	ovl_nlink_end(old, locked);
746
+	ovl_nlink_end(old);
710
747
 out_drop_write:
711
748
 	ovl_drop_write(old);
712
749
 out:
..
..
@@ -721,6 +758,7 @@
721
758
 static int ovl_remove_and_whiteout(struct dentry *dentry,
722
759
 				   struct list_head *list)
723
760
 {
761
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
724
762
 	struct dentry *workdir = ovl_workdir(dentry);
725
763
 	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
726
764
 	struct dentry *upper;
..
..
@@ -754,7 +792,7 @@
754
792
 		goto out_dput_upper;
755
793
 	}
756
794
 
757
-	err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);
795
+	err = ovl_cleanup_and_whiteout(ofs, d_inode(upperdir), upper);
758
796
 	if (err)
759
797
 		goto out_d_drop;
760
798
 
..
..
@@ -828,10 +866,31 @@
828
866
 	       !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry));
829
867
 }
830
868
 
869
+static void ovl_drop_nlink(struct dentry *dentry)
870
+{
871
+	struct inode *inode = d_inode(dentry);
872
+	struct dentry *alias;
873
+
874
+	/* Try to find another, hashed alias */
875
+	spin_lock(&inode->i_lock);
876
+	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
877
+		if (alias != dentry && !d_unhashed(alias))
878
+			break;
879
+	}
880
+	spin_unlock(&inode->i_lock);
881
+
882
+	/*
883
+	 * Changes to underlying layers may cause i_nlink to lose sync with
884
+	 * reality.  In this case prevent the link count from going to zero
885
+	 * prematurely.
886
+	 */
887
+	if (inode->i_nlink > !!alias)
888
+		drop_nlink(inode);
889
+}
890
+
831
891
 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
832
892
 {
833
893
 	int err;
834
-	bool locked = false;
835
894
 	const struct cred *old_cred;
836
895
 	struct dentry *upperdentry;
837
896
 	bool lower_positive = ovl_lower_positive(dentry);
..
..
@@ -852,7 +911,7 @@
852
911
 	if (err)
853
912
 		goto out_drop_write;
854
913
 
855
-	err = ovl_nlink_start(dentry, &locked);
914
+	err = ovl_nlink_start(dentry);
856
915
 	if (err)
857
916
 		goto out_drop_write;
858
917
 
..
..
@@ -861,14 +920,14 @@
861
920
 		err = ovl_remove_upper(dentry, is_dir, &list);
862
921
 	else
863
922
 		err = ovl_remove_and_whiteout(dentry, &list);
864
-	ovl_revert_creds(old_cred);
923
+	ovl_revert_creds(dentry->d_sb, old_cred);
865
924
 	if (!err) {
866
925
 		if (is_dir)
867
926
 			clear_nlink(dentry->d_inode);
868
927
 		else
869
-			drop_nlink(dentry->d_inode);
928
+			ovl_drop_nlink(dentry);
870
929
 	}
871
-	ovl_nlink_end(dentry, locked);
930
+	ovl_nlink_end(dentry);
872
931
 
873
932
 	/*
874
933
 	 * Copy ctime
..
..
@@ -1019,7 +1078,7 @@
1019
1078
 		spin_unlock(&dentry->d_lock);
1020
1079
 	} else {
1021
1080
 		kfree(redirect);
1022
-		pr_warn_ratelimited("overlayfs: failed to set redirect (%i)\n",
1081
+		pr_warn_ratelimited("failed to set redirect (%i)\n",
1023
1082
 				    err);
1024
1083
 		/* Fall back to userspace copy-up */
1025
1084
 		err = -EXDEV;
..
..
@@ -1032,7 +1091,6 @@
1032
1091
 		      unsigned int flags)
1033
1092
 {
1034
1093
 	int err;
1035
-	bool locked = false;
1036
1094
 	struct dentry *old_upperdir;
1037
1095
 	struct dentry *new_upperdir;
1038
1096
 	struct dentry *olddentry;
..
..
@@ -1041,6 +1099,7 @@
1041
1099
 	bool old_opaque;
1042
1100
 	bool new_opaque;
1043
1101
 	bool cleanup_whiteout = false;
1102
+	bool update_nlink = false;
1044
1103
 	bool overwrite = !(flags & RENAME_EXCHANGE);
1045
1104
 	bool is_dir = d_is_dir(old);
1046
1105
 	bool new_is_dir = d_is_dir(new);
..
..
@@ -1098,10 +1157,12 @@
1098
1157
 		err = ovl_copy_up(new);
1099
1158
 		if (err)
1100
1159
 			goto out_drop_write;
1101
-	} else {
1102
-		err = ovl_nlink_start(new, &locked);
1160
+	} else if (d_inode(new)) {
1161
+		err = ovl_nlink_start(new);
1103
1162
 		if (err)
1104
1163
 			goto out_drop_write;
1164
+
1165
+		update_nlink = true;
1105
1166
 	}
1106
1167
 
1107
1168
 	old_cred = ovl_override_creds(old->d_sb);
..
..
@@ -1213,7 +1274,7 @@
1213
1274
 		if (new_is_dir)
1214
1275
 			clear_nlink(d_inode(new));
1215
1276
 		else
1216
-			drop_nlink(d_inode(new));
1277
+			ovl_drop_nlink(new);
1217
1278
 	}
1218
1279
 
1219
1280
 	ovl_dir_modified(old->d_parent, ovl_type_origin(old) ||
..
..
@@ -1233,8 +1294,9 @@
1233
1294
 out_unlock:
1234
1295
 	unlock_rename(new_upperdir, old_upperdir);
1235
1296
 out_revert_creds:
1236
-	ovl_revert_creds(old_cred);
1237
-	ovl_nlink_end(new, locked);
1297
+	ovl_revert_creds(old->d_sb, old_cred);
1298
+	if (update_nlink)
1299
+		ovl_nlink_end(new);
1238
1300
 out_drop_write:
1239
1301
 	ovl_drop_write(old);
1240
1302
 out: