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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d 
 kernel/fs/overlayfs/readdir.c
....@@ -1,10 +1,7 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  *
34  * 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.
85  */
96 
107 #include <linux/fs.h>
....@@ -289,7 +286,7 @@
289286 		}
290287 		inode_unlock(dir->d_inode);
291288 	}
292
-	ovl_revert_creds(old_cred);
289
+	ovl_revert_creds(rdd->dentry->d_sb, old_cred);
293290 
294291 	return err;
295292 }
....@@ -300,7 +297,7 @@
300297 	struct file *realfile;
301298 	int err;
302299 
303
-	realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
300
+	realfile = ovl_path_open(realpath, O_RDONLY | O_LARGEFILE);
304301 	if (IS_ERR(realfile))
305302 		return PTR_ERR(realfile);
306303 
....@@ -320,18 +317,6 @@
320317 	fput(realfile);
321318 
322319 	return err;
323
-}
324
-
325
-/*
326
- * Can we iterate real dir directly?
327
- *
328
- * Non-merge dir may contain whiteouts from a time it was a merge upper, before
329
- * lower dir was removed under it and possibly before it was rotated from upper
330
- * to lower layer.
331
- */
332
-static bool ovl_dir_is_real(struct dentry *dir)
333
-{
334
-	return !ovl_test_flag(OVL_WHITEOUTS, d_inode(dir));
335320 }
336321 
337322 static void ovl_dir_reset(struct file *file)
....@@ -441,15 +426,23 @@
441426 
442427 /* Map inode number to lower fs unique range */
443428 static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
444
-			       const char *name, int namelen)
429
+			       const char *name, int namelen, bool warn)
445430 {
446
-	if (ino >> (64 - xinobits)) {
447
-		pr_warn_ratelimited("overlayfs: d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
448
-				    namelen, name, ino, xinobits);
431
+	unsigned int xinoshift = 64 - xinobits;
432
+
433
+	if (unlikely(ino >> xinoshift)) {
434
+		if (warn) {
435
+			pr_warn_ratelimited("d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
436
+					    namelen, name, ino, xinobits);
437
+		}
449438 		return ino;
450439 	}
451440 
452
-	return ino | ((u64)fsid) << (64 - xinobits);
441
+	/*
442
+	 * The lowest xinobit is reserved for mapping the non-peresistent inode
443
+	 * numbers range, but this range is only exposed via st_ino, not here.
444
+	 */
445
+	return ino | ((u64)fsid) << (xinoshift + 1);
453446 }
454447 
455448 /*
....@@ -472,7 +465,7 @@
472465 	int xinobits = ovl_xino_bits(dir->d_sb);
473466 	int err = 0;
474467 
475
-	if (!ovl_same_sb(dir->d_sb) && !xinobits)
468
+	if (!ovl_same_dev(dir->d_sb))
476469 		goto out;
477470 
478471 	if (p->name[0] == '.') {
....@@ -518,7 +511,8 @@
518511 	} else if (xinobits && !OVL_TYPE_UPPER(type)) {
519512 		ino = ovl_remap_lower_ino(ino, xinobits,
520513 					  ovl_layer_lower(this)->fsid,
521
-					  p->name, p->len);
514
+					  p->name, p->len,
515
+					  ovl_xino_warn(dir->d_sb));
522516 	}
523517 
524518 out:
....@@ -527,7 +521,7 @@
527521 	return err;
528522 
529523 fail:
530
-	pr_warn_ratelimited("overlayfs: failed to look up (%s) for ino (%i)\n",
524
+	pr_warn_ratelimited("failed to look up (%s) for ino (%i)\n",
531525 			    p->name, err);
532526 	goto out;
533527 }
....@@ -600,6 +594,7 @@
600594 {
601595 	int res;
602596 	struct dentry *dentry = path->dentry;
597
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
603598 	struct ovl_dir_cache *cache;
604599 
605600 	cache = ovl_dir_cache(d_inode(dentry));
....@@ -626,7 +621,7 @@
626621 		 * Removing the "impure" xattr is best effort.
627622 		 */
628623 		if (!ovl_want_write(dentry)) {
629
-			ovl_do_removexattr(ovl_dentry_upper(dentry),
624
+			ovl_do_removexattr(ofs, ovl_dentry_upper(dentry),
630625 					   OVL_XATTR_IMPURE);
631626 			ovl_drop_write(dentry);
632627 		}
....@@ -648,6 +643,7 @@
648643 	u64 parent_ino;
649644 	int fsid;
650645 	int xinobits;
646
+	bool xinowarn;
651647 };
652648 
653649 static int ovl_fill_real(struct dir_context *ctx, const char *name,
....@@ -668,7 +664,7 @@
668664 			ino = p->ino;
669665 	} else if (rdt->xinobits) {
670666 		ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,
671
-					  name, namelen);
667
+					  name, namelen, rdt->xinowarn);
672668 	}
673669 
674670 	return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
....@@ -694,11 +690,12 @@
694690 	int err;
695691 	struct ovl_dir_file *od = file->private_data;
696692 	struct dentry *dir = file->f_path.dentry;
697
-	struct ovl_layer *lower_layer = ovl_layer_lower(dir);
693
+	const struct ovl_layer *lower_layer = ovl_layer_lower(dir);
698694 	struct ovl_readdir_translate rdt = {
699695 		.ctx.actor = ovl_fill_real,
700696 		.orig_ctx = ctx,
701697 		.xinobits = ovl_xino_bits(dir->d_sb),
698
+		.xinowarn = ovl_xino_warn(dir->d_sb),
702699 	};
703700 
704701 	if (rdt.xinobits && lower_layer)
....@@ -735,8 +732,10 @@
735732 	struct ovl_dir_file *od = file->private_data;
736733 	struct dentry *dentry = file->f_path.dentry;
737734 	struct ovl_cache_entry *p;
735
+	const struct cred *old_cred;
738736 	int err;
739737 
738
+	old_cred = ovl_override_creds(dentry->d_sb);
740739 	if (!ctx->pos)
741740 		ovl_dir_reset(file);
742741 
....@@ -747,20 +746,23 @@
747746 		 * entries.
748747 		 */
749748 		if (ovl_xino_bits(dentry->d_sb) ||
750
-		    (ovl_same_sb(dentry->d_sb) &&
749
+		    (ovl_same_fs(dentry->d_sb) &&
751750 		     (ovl_is_impure_dir(file) ||
752751 		      OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
753
-			return ovl_iterate_real(file, ctx);
752
+			err = ovl_iterate_real(file, ctx);
753
+		} else {
754
+			err = iterate_dir(od->realfile, ctx);
754755 		}
755
-		return iterate_dir(od->realfile, ctx);
756
+		goto out;
756757 	}
757758 
758759 	if (!od->cache) {
759760 		struct ovl_dir_cache *cache;
760761 
761762 		cache = ovl_cache_get(dentry);
763
+		err = PTR_ERR(cache);
762764 		if (IS_ERR(cache))
763
-			return PTR_ERR(cache);
765
+			goto out;
764766 
765767 		od->cache = cache;
766768 		ovl_seek_cursor(od, ctx->pos);
....@@ -772,7 +774,7 @@
772774 			if (!p->ino) {
773775 				err = ovl_cache_update_ino(&file->f_path, p);
774776 				if (err)
775
-					return err;
777
+					goto out;
776778 			}
777779 			if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
778780 				break;
....@@ -780,7 +782,10 @@
780782 		od->cursor = p->l_node.next;
781783 		ctx->pos++;
782784 	}
783
-	return 0;
785
+	err = 0;
786
+out:
787
+	ovl_revert_creds(dentry->d_sb, old_cred);
788
+	return err;
784789 }
785790 
786791 static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
....@@ -823,46 +828,76 @@
823828 	return res;
824829 }
825830 
826
-static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
827
-			 int datasync)
831
+static struct file *ovl_dir_open_realfile(const struct file *file,
832
+					  struct path *realpath)
828833 {
834
+	struct file *res;
835
+	const struct cred *old_cred;
836
+
837
+	old_cred = ovl_override_creds(file_inode(file)->i_sb);
838
+	res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));
839
+	ovl_revert_creds(file_inode(file)->i_sb, old_cred);
840
+
841
+	return res;
842
+}
843
+
844
+/*
845
+ * Like ovl_real_fdget(), returns upperfile if dir was copied up since open.
846
+ * Unlike ovl_real_fdget(), this caches upperfile in file->private_data.
847
+ *
848
+ * TODO: use same abstract type for file->private_data of dir and file so
849
+ * upperfile could also be cached for files as well.
850
+ */
851
+struct file *ovl_dir_real_file(const struct file *file, bool want_upper)
852
+{
853
+
829854 	struct ovl_dir_file *od = file->private_data;
830855 	struct dentry *dentry = file->f_path.dentry;
831
-	struct file *realfile = od->realfile;
856
+	struct file *old, *realfile = od->realfile;
832857 
833
-	/* Nothing to sync for lower */
834858 	if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
835
-		return 0;
859
+		return want_upper ? NULL : realfile;
836860 
837861 	/*
838862 	 * Need to check if we started out being a lower dir, but got copied up
839863 	 */
840864 	if (!od->is_upper) {
841
-		struct inode *inode = file_inode(file);
842
-
843865 		realfile = READ_ONCE(od->upperfile);
844866 		if (!realfile) {
845867 			struct path upperpath;
846868 
847869 			ovl_path_upper(dentry, &upperpath);
848
-			realfile = ovl_path_open(&upperpath, O_RDONLY);
870
+			realfile = ovl_dir_open_realfile(file, &upperpath);
871
+			if (IS_ERR(realfile))
872
+				return realfile;
849873 
850
-			inode_lock(inode);
851
-			if (!od->upperfile) {
852
-				if (IS_ERR(realfile)) {
853
-					inode_unlock(inode);
854
-					return PTR_ERR(realfile);
855
-				}
856
-				smp_store_release(&od->upperfile, realfile);
857
-			} else {
858
-				/* somebody has beaten us to it */
859
-				if (!IS_ERR(realfile))
860
-					fput(realfile);
861
-				realfile = od->upperfile;
874
+			old = cmpxchg_release(&od->upperfile, NULL, realfile);
875
+			if (old) {
876
+				fput(realfile);
877
+				realfile = old;
862878 			}
863
-			inode_unlock(inode);
864879 		}
865880 	}
881
+
882
+	return realfile;
883
+}
884
+
885
+static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
886
+			 int datasync)
887
+{
888
+	struct file *realfile;
889
+	int err;
890
+
891
+	err = ovl_sync_status(OVL_FS(file->f_path.dentry->d_sb));
892
+	if (err <= 0)
893
+		return err;
894
+
895
+	realfile = ovl_dir_real_file(file, true);
896
+	err = PTR_ERR_OR_ZERO(realfile);
897
+
898
+	/* Nothing to sync for lower */
899
+	if (!realfile || err)
900
+		return err;
866901 
867902 	return vfs_fsync_range(realfile, start, end, datasync);
868903 }
....@@ -896,7 +931,7 @@
896931 		return -ENOMEM;
897932 
898933 	type = ovl_path_real(file->f_path.dentry, &realpath);
899
-	realfile = ovl_path_open(&realpath, file->f_flags);
934
+	realfile = ovl_dir_open_realfile(file, &realpath);
900935 	if (IS_ERR(realfile)) {
901936 		kfree(od);
902937 		return PTR_ERR(realfile);
....@@ -916,6 +951,10 @@
916951 	.llseek		= ovl_dir_llseek,
917952 	.fsync		= ovl_dir_fsync,
918953 	.release	= ovl_dir_release,
954
+	.unlocked_ioctl	= ovl_ioctl,
955
+#ifdef CONFIG_COMPAT
956
+	.compat_ioctl	= ovl_compat_ioctl,
957
+#endif
919958 };
920959 
921960 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
....@@ -927,7 +966,7 @@
927966 
928967 	old_cred = ovl_override_creds(dentry->d_sb);
929968 	err = ovl_dir_read_merged(dentry, list, &root);
930
-	ovl_revert_creds(old_cred);
969
+	ovl_revert_creds(dentry->d_sb, old_cred);
931970 	if (err)
932971 		return err;
933972 
....@@ -974,7 +1013,7 @@
9741013 
9751014 		dentry = lookup_one_len(p->name, upper, p->len);
9761015 		if (IS_ERR(dentry)) {
977
-			pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n",
1016
+			pr_err("lookup '%s/%.*s' failed (%i)\n",
9781017 			       upper->d_name.name, p->len, p->name,
9791018 			       (int) PTR_ERR(dentry));
9801019 			continue;
....@@ -1022,7 +1061,9 @@
10221061 	return rdd.d_type_supported;
10231062 }
10241063 
1025
-static void ovl_workdir_cleanup_recurse(struct path *path, int level)
1064
+#define OVL_INCOMPATDIR_NAME "incompat"
1065
+
1066
+static int ovl_workdir_cleanup_recurse(struct path *path, int level)
10261067 {
10271068 	int err;
10281069 	struct inode *dir = path->dentry->d_inode;
....@@ -1036,6 +1077,19 @@
10361077 		.root = &root,
10371078 		.is_lowest = false,
10381079 	};
1080
+	bool incompat = false;
1081
+
1082
+	/*
1083
+	 * The "work/incompat" directory is treated specially - if it is not
1084
+	 * empty, instead of printing a generic error and mounting read-only,
1085
+	 * we will error about incompat features and fail the mount.
1086
+	 *
1087
+	 * When called from ovl_indexdir_cleanup(), path->dentry->d_name.name
1088
+	 * starts with '#'.
1089
+	 */
1090
+	if (level == 2 &&
1091
+	    !strcmp(path->dentry->d_name.name, OVL_INCOMPATDIR_NAME))
1092
+		incompat = true;
10391093 
10401094 	err = ovl_dir_read(path, &rdd);
10411095 	if (err)
....@@ -1050,27 +1104,34 @@
10501104 				continue;
10511105 			if (p->len == 2 && p->name[1] == '.')
10521106 				continue;
1107
+		} else if (incompat) {
1108
+			pr_err("overlay with incompat feature '%s' cannot be mounted\n",
1109
+				p->name);
1110
+			err = -EINVAL;
1111
+			break;
10531112 		}
10541113 		dentry = lookup_one_len(p->name, path->dentry, p->len);
10551114 		if (IS_ERR(dentry))
10561115 			continue;
10571116 		if (dentry->d_inode)
1058
-			ovl_workdir_cleanup(dir, path->mnt, dentry, level);
1117
+			err = ovl_workdir_cleanup(dir, path->mnt, dentry, level);
10591118 		dput(dentry);
1119
+		if (err)
1120
+			break;
10601121 	}
10611122 	inode_unlock(dir);
10621123 out:
10631124 	ovl_cache_free(&list);
1125
+	return err;
10641126 }
10651127 
1066
-void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
1128
+int ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
10671129 			 struct dentry *dentry, int level)
10681130 {
10691131 	int err;
10701132 
10711133 	if (!d_is_dir(dentry) || level > 1) {
1072
-		ovl_cleanup(dir, dentry);
1073
-		return;
1134
+		return ovl_cleanup(dir, dentry);
10741135 	}
10751136 
10761137 	err = ovl_do_rmdir(dir, dentry);
....@@ -1078,10 +1139,13 @@
10781139 		struct path path = { .mnt = mnt, .dentry = dentry };
10791140 
10801141 		inode_unlock(dir);
1081
-		ovl_workdir_cleanup_recurse(&path, level + 1);
1142
+		err = ovl_workdir_cleanup_recurse(&path, level + 1);
10821143 		inode_lock_nested(dir, I_MUTEX_PARENT);
1083
-		ovl_cleanup(dir, dentry);
1144
+		if (!err)
1145
+			err = ovl_cleanup(dir, dentry);
10841146 	}
1147
+
1148
+	return err;
10851149 }
10861150 
10871151 int ovl_indexdir_cleanup(struct ovl_fs *ofs)
....@@ -1090,7 +1154,7 @@
10901154 	struct dentry *indexdir = ofs->indexdir;
10911155 	struct dentry *index = NULL;
10921156 	struct inode *dir = indexdir->d_inode;
1093
-	struct path path = { .mnt = ofs->upper_mnt, .dentry = indexdir };
1157
+	struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = indexdir };
10941158 	LIST_HEAD(list);
10951159 	struct rb_root root = RB_ROOT;
10961160 	struct ovl_cache_entry *p;
....@@ -1120,6 +1184,13 @@
11201184 			index = NULL;
11211185 			break;
11221186 		}
1187
+		/* Cleanup leftover from index create/cleanup attempt */
1188
+		if (index->d_name.name[0] == '#') {
1189
+			err = ovl_workdir_cleanup(dir, path.mnt, index, 1);
1190
+			if (err)
1191
+				break;
1192
+			goto next;
1193
+		}
11231194 		err = ovl_verify_index(ofs, index);
11241195 		if (!err) {
11251196 			goto next;
....@@ -1138,7 +1209,7 @@
11381209 			 * Whiteout orphan index to block future open by
11391210 			 * handle after overlay nlink dropped to zero.
11401211 			 */
1141
-			err = ovl_cleanup_and_whiteout(indexdir, dir, index);
1212
+			err = ovl_cleanup_and_whiteout(ofs, dir, index);
11421213 		} else {
11431214 			/* Cleanup orphan index entries */
11441215 			err = ovl_cleanup(dir, index);
....@@ -1156,6 +1227,6 @@
11561227 out:
11571228 	ovl_cache_free(&list);
11581229 	if (err)
1159
-		pr_err("overlayfs: failed index dir cleanup (%i)\n", err);
1230
+		pr_err("failed index dir cleanup (%i)\n", err);
11601231 	return err;
11611232 }