[PATCH NOMERGE 08/13] fscrypt: Introduce charset-based matching functions

[Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxxxx>]

Changes since RFC v1:
  - Send length of both strings to comparison functions.
  - Change length type to size_t.

Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxxxx>
---
 include/linux/fscrypt.h         |  1 +
 include/linux/fscrypt_notsupp.h | 16 ++++++++++++++++
 include/linux/fscrypt_supp.h    | 27 +++++++++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 952ab97af325..96559f7bfc63 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -15,6 +15,7 @@
 #define _LINUX_FSCRYPT_H
 
 #include <linux/fs.h>
+#include <linux/nls.h>
 
 #define FS_CRYPTO_BLOCK_SIZE		16
 
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 44b50c04bae9..f38824aa3250 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -159,6 +159,22 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
 	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
 }
 
+static inline bool fscrypt_charset_match_name(struct nls_table *charset,
+					      const struct fscrypt_name *fname,
+					      const u8 *de_name,
+					      u32 de_name_len, bool ignorecase)
+{
+	if (!ignorecase) {
+		return !nls_strncmp(charset, (char *) de_name, de_name_len,
+				    fname->disk_name.name,
+				    fname->disk_name.len);
+	}
+
+	return !nls_strncasecmp(charset, (char *) de_name,
+				(size_t) de_name_len, fname->disk_name.name,
+				(size_t) fname->disk_name.len);
+}
+
 /* bio.c */
 static inline void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx,
 					     struct bio *bio)
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index 477a7a6504d2..8c55678ce9ce 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -187,6 +187,33 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
 	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
 }
 
+static inline bool fscrypt_charset_match_name(struct nls_table *charset,
+					      const struct fscrypt_name *fname,
+					      const u8 *de_name,
+					      u32 de_name_len, bool ignorecase)
+{
+	if (unlikely(!fname->disk_name.name)) {
+		const struct fscrypt_digested_name *n =
+			(const void *)fname->crypto_buf.name;
+		if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
+			return false;
+		if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
+			return false;
+		return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len),
+			       n->digest, FSCRYPT_FNAME_DIGEST_SIZE);
+	}
+
+	if (!ignorecase) {
+		return !nls_strncmp(charset, (char *) de_name, de_name_len,
+				    fname->disk_name.name,
+				    fname->disk_name.len);
+	}
+
+	return !nls_strncasecmp(charset, (char *) de_name, de_name_len,
+				fname->disk_name.name,
+				fname->disk_name.len);
+}
+
 /* bio.c */
 extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
 extern void fscrypt_pullback_bio_page(struct page **, bool);
-- 
2.17.0