linux-ext4 - [PATCH RFC v2 11/13] fscrypt: Introduce charset-based matching functions

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Message-Id: <20180125025349.31494-12-krisman@collabora.co.uk>
Date:   Thu, 25 Jan 2018 00:53:47 -0200
From:   Gabriel Krisman Bertazi <krisman@...labora.co.uk>
To:     tytso@....edu, david@...morbit.com, olaf@....com,
        viro@...iv.linux.org.uk
Cc:     linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        alvaro.soliverez@...labora.co.uk, kernel@...ts.collabora.co.uk,
        Gabriel Krisman Bertazi <krisman@...labora.co.uk>
Subject: [PATCH RFC v2 11/13] fscrypt: Introduce charset-based matching functions

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@...labora.co.uk>
---
 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 08b4b40c5aa8..8ca010ef2871 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -21,6 +21,7 @@
 #include <linux/dcache.h>
 #include <crypto/skcipher.h>
 #include <uapi/linux/fs.h>
+#include <linux/charsets.h>
 
 #define FS_CRYPTO_BLOCK_SIZE		16
 
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 63e58808519a..d790052b8cbe 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -160,6 +160,22 @@ 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(const struct fscrypt_name *fname,
+					      const struct charset *charset,
+					      const u8 *de_name,
+					      u32 de_name_len, bool ignorecase)
+{
+	if (!ignorecase) {
+		return !charset_strncmp(charset, (char *) de_name, de_name_len,
+					fname->disk_name.name,
+					fname->disk_name.len);
+	}
+
+	return !charset_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 cf9e9fc02f0a..8ef12553a174 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -138,6 +138,33 @@ 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(const struct fscrypt_name *fname,
+					      const struct charset *charset,
+					      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 !charset_strncmp(charset, (char *) de_name, de_name_len,
+					fname->disk_name.name,
+					fname->disk_name.len);
+	}
+
+	return !charset_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);
-- 
2.15.1