ANDROID: sync encrypt+casefold support with patches going upstream

The following patches are now queued in f2fs/dev for 5.11, but
android-mainline and android12-5.4 have an old version of them:

	libfs: Add generic function for setting dentry_ops
	fscrypt: Have filesystems handle their d_ops
	f2fs: Handle casefolding with Encryption

Get them up-to-date.

Link: https://lore.kernel.org/linux-f2fs-devel/20201119060904.463807-1-drosen@google.com
Bug: 161184936
Test: kvm-xfstests -c f2fs/default,f2fs/encrypt -g casefold
Change-Id: I359bf4f23631c1b8175de8d5f12d0787fd7f42bd
Signed-off-by: Eric Biggers <ebiggers@google.com>

fs/ext4/ext4.h

@@ -3427,10 +3427,6 @@ static inline void ext4_unlock_group(struct super_block *sb,
 /* dir.c */
 extern const struct file_operations ext4_dir_operations;
 
-#ifdef CONFIG_UNICODE
-extern const struct dentry_operations ext4_dentry_ops;
-#endif
-
 /* file.c */
 extern const struct inode_operations ext4_file_inode_operations;
 extern const struct file_operations ext4_file_operations;

fs/ext4/namei.c

@@ -1697,7 +1697,7 @@ static struct buffer_head *ext4_lookup_entry(struct inode *dir,
 	struct buffer_head *bh;
 
 	err = ext4_fname_prepare_lookup(dir, dentry, &fname);
-	generic_set_encrypted_ci_d_ops(dir, dentry);
+	generic_set_encrypted_ci_d_ops(dentry);
 	if (err == -ENOENT)
 		return NULL;
 	if (err)

fs/f2fs/dir.c

@@ -207,8 +207,10 @@ static struct f2fs_dir_entry *find_in_block(struct inode *dir,
 /*
  * Test whether a case-insensitive directory entry matches the filename
  * being searched for.
+ *
+ * Returns 1 for a match, 0 for no match, and -errno on an error.
  */
-static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name,
+static int f2fs_match_ci_name(const struct inode *dir, const struct qstr *name,
 			       const u8 *de_name, u32 de_name_len)
 {
 	const struct super_block *sb = dir->i_sb;
@@ -222,11 +224,11 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name,
 			FSTR_INIT((u8 *)de_name, de_name_len);
 
 		if (WARN_ON_ONCE(!fscrypt_has_encryption_key(dir)))
-			return false;
+			return -EINVAL;
 
 		decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL);
 		if (!decrypted_name.name)
-			return false;
+			return -ENOMEM;
 		res = fscrypt_fname_disk_to_usr(dir, 0, 0, &encrypted_name,
 						&decrypted_name);
 		if (res < 0)
@@ -236,23 +238,24 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name,
 	}
 
 	res = utf8_strncasecmp_folded(um, name, &entry);
-	if (res < 0) {
-		/*
-		 * In strict mode, ignore invalid names.  In non-strict mode,
-		 * fall back to treating them as opaque byte sequences.
-		 */
-		if (sb_has_strict_encoding(sb) || name->len != entry.len)
-			res = 1;
-		else
-			res = memcmp(name->name, entry.name, name->len);
+	/*
+	 * In strict mode, ignore invalid names.  In non-strict mode,
+	 * fall back to treating them as opaque byte sequences.
+	 */
+	if (res < 0 && !sb_has_strict_encoding(sb)) {
+		res = name->len == entry.len &&
+				memcmp(name->name, entry.name, name->len) == 0;
+	} else {
+		/* utf8_strncasecmp_folded returns 0 on match */
+		res = (res == 0);
 	}
 out:
 	kfree(decrypted_name.name);
-	return res == 0;
+	return res;
 }
 #endif /* CONFIG_UNICODE */
 
-static inline bool f2fs_match_name(const struct inode *dir,
+static inline int f2fs_match_name(const struct inode *dir,
 				   const struct f2fs_filename *fname,
 				   const u8 *de_name, u32 de_name_len)
 {
@@ -279,6 +282,7 @@ struct f2fs_dir_entry *f2fs_find_target_dentry(const struct f2fs_dentry_ptr *d,
 	struct f2fs_dir_entry *de;
 	unsigned long bit_pos = 0;
 	int max_len = 0;
+	int res = 0;
 
 	if (max_slots)
 		*max_slots = 0;
@@ -296,10 +300,15 @@ struct f2fs_dir_entry *f2fs_find_target_dentry(const struct f2fs_dentry_ptr *d,
 			continue;
 		}
 
-		if (de->hash_code == fname->hash &&
-		    f2fs_match_name(d->inode, fname, d->filename[bit_pos],
-				    le16_to_cpu(de->name_len)))
-			goto found;
+		if (de->hash_code == fname->hash) {
+			res = f2fs_match_name(d->inode, fname,
+					      d->filename[bit_pos],
+					      le16_to_cpu(de->name_len));
+			if (res < 0)
+				return ERR_PTR(res);
+			if (res)
+				goto found;
+		}
 
 		if (max_slots && max_len > *max_slots)
 			*max_slots = max_len;
@@ -349,7 +358,11 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir,
 		}
 
 		de = find_in_block(dir, dentry_page, fname, &max_slots);
-		if (de) {
+		if (IS_ERR(de)) {
+			*res_page = ERR_CAST(de);
+			de = NULL;
+			break;
+		} else if (de) {
 			*res_page = dentry_page;
 			break;
 		}

fs/f2fs/inline.c

@@ -350,6 +350,10 @@ struct f2fs_dir_entry *f2fs_find_in_inline_dir(struct inode *dir,
 	make_dentry_ptr_inline(dir, &d, inline_dentry);
 	de = f2fs_find_target_dentry(&d, fname, NULL);
 	unlock_page(ipage);
+	if (IS_ERR(de)) {
+		*res_page = ERR_CAST(de);
+		de = NULL;
+	}
 	if (de)
 		*res_page = ipage;
 	else

fs/f2fs/namei.c

@@ -497,7 +497,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 	}
 
 	err = f2fs_prepare_lookup(dir, dentry, &fname);
-	generic_set_encrypted_ci_d_ops(dir, dentry);
+	generic_set_encrypted_ci_d_ops(dentry);
 	if (err == -ENOENT)
 		goto out_splice;
 	if (err)

fs/libfs.c

@@ -1464,7 +1464,7 @@ static const struct dentry_operations generic_encrypted_dentry_ops = {
 };
 #endif
 
-#if IS_ENABLED(CONFIG_UNICODE) && IS_ENABLED(CONFIG_FS_ENCRYPTION)
+#if defined(CONFIG_FS_ENCRYPTION) && defined(CONFIG_UNICODE)
 static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
 	.d_hash = generic_ci_d_hash,
 	.d_compare = generic_ci_d_compare,
@@ -1474,28 +1474,48 @@ static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
 
 /**
  * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
- * @dir:	parent of dentry whose ops to set
- * @dentry:	detnry to set ops on
+ * @dentry:	dentry to set ops on
  *
- * This function sets the dentry ops for the given dentry to handle both
- * casefolding and encryption of the dentry name.
+ * Casefolded directories need d_hash and d_compare set, so that the dentries
+ * contained in them are handled case-insensitively.  Note that these operations
+ * are needed on the parent directory rather than on the dentries in it, and
+ * while the casefolding flag can be toggled on and off on an empty directory,
+ * dentry_operations can't be changed later.  As a result, if the filesystem has
+ * casefolding support enabled at all, we have to give all dentries the
+ * casefolding operations even if their inode doesn't have the casefolding flag
+ * currently (and thus the casefolding ops would be no-ops for now).
+ *
+ * Encryption works differently in that the only dentry operation it needs is
+ * d_revalidate, which it only needs on dentries that have the no-key name flag.
+ * The no-key flag can't be set "later", so we don't have to worry about that.
+ *
+ * Finally, to maximize compatibility with overlayfs (which isn't compatible
+ * with certain dentry operations) and to avoid taking an unnecessary
+ * performance hit, we use custom dentry_operations for each possible
+ * combination rather than always installing all operations.
  */
-void generic_set_encrypted_ci_d_ops(struct inode *dir, struct dentry *dentry)
+void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
 {
 #ifdef CONFIG_FS_ENCRYPTION
-	if (dentry->d_flags & DCACHE_NOKEY_NAME) {
-#ifdef CONFIG_UNICODE
-		if (dir->i_sb->s_encoding) {
-			d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
-			return;
-		}
+	bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
 #endif
+#ifdef CONFIG_UNICODE
+	bool needs_ci_ops = dentry->d_sb->s_encoding;
+#endif
+#if defined(CONFIG_FS_ENCRYPTION) && defined(CONFIG_UNICODE)
+	if (needs_encrypt_ops && needs_ci_ops) {
+		d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
+		return;
+	}
+#endif
+#ifdef CONFIG_FS_ENCRYPTION
+	if (needs_encrypt_ops) {
 		d_set_d_op(dentry, &generic_encrypted_dentry_ops);
 		return;
 	}
 #endif
 #ifdef CONFIG_UNICODE
-	if (dir->i_sb->s_encoding) {
+	if (needs_ci_ops) {
 		d_set_d_op(dentry, &generic_ci_dentry_ops);
 		return;
 	}

fs/ubifs/dir.c

@@ -190,7 +190,6 @@ static int dbg_check_name(const struct ubifs_info *c,
 	return 0;
 }
 
-static void ubifs_set_d_ops(struct inode *dir, struct dentry *dentry);
 static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
 				   unsigned int flags)
 {
@@ -204,7 +203,7 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
 	dbg_gen("'%pd' in dir ino %lu", dentry, dir->i_ino);
 
 	err = fscrypt_prepare_lookup(dir, dentry, &nm);
-	ubifs_set_d_ops(dir, dentry);
+	generic_set_encrypted_ci_d_ops(dentry);
 	if (err == -ENOENT)
 		return d_splice_alias(NULL, dentry);
 	if (err)
@@ -1651,19 +1650,3 @@ const struct file_operations ubifs_dir_operations = {
 	.compat_ioctl   = ubifs_compat_ioctl,
 #endif
 };
-
-#ifdef CONFIG_FS_ENCRYPTION
-static const struct dentry_operations ubifs_encrypted_dentry_ops = {
-	.d_revalidate = fscrypt_d_revalidate,
-};
-#endif
-
-static void ubifs_set_d_ops(struct inode *dir, struct dentry *dentry)
-{
-#ifdef CONFIG_FS_ENCRYPTION
-	if (dentry->d_flags & DCACHE_NOKEY_NAME) {
-		d_set_d_op(dentry, &ubifs_encrypted_dentry_ops);
-		return;
-	}
-#endif
-}

include/linux/fs.h

@@ -3202,8 +3202,7 @@ extern int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str);
 extern int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
 				const char *str, const struct qstr *name);
 #endif
-extern void generic_set_encrypted_ci_d_ops(struct inode *dir,
-					   struct dentry *dentry);
+extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry);
 
 #ifdef CONFIG_MIGRATION
 extern int buffer_migrate_page(struct address_space *,

include/linux/fscrypt.h

@@ -774,9 +774,11 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir,
  * directory's encryption key is available, then the lookup is assumed to be by
  * plaintext name; otherwise, it is assumed to be by no-key name.
  *
- * After calling this function, a filesystem should ensure that its dentry
- * operations contain fscrypt_d_revalidate if DCACHE_NOKEY_NAME was set,
- * so that the dentry can be invalidated if the key is later added.
+ * This will set DCACHE_NOKEY_NAME on the dentry if the lookup is by no-key
+ * name.  In this case the filesystem must assign the dentry a dentry_operations
+ * which contains fscrypt_d_revalidate (or contains a d_revalidate method that
+ * calls fscrypt_d_revalidate), so that the dentry will be invalidated if the
+ * directory's encryption key is later added.
  *
  * Return: 0 on success; -ENOENT if the directory's key is unavailable but the
  * filename isn't a valid no-key name, so a negative dentry should be created;