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From: Amir Goldstein <amir73il@gmail.com>
To: Jan Kara <jack@suse.cz>
Cc: Matthew Bobrowski <mbobrowski@mbobrowski.org>,
	linux-fsdevel@vger.kernel.org
Subject: [PATCH v3 05/11] fanotify: use macros to get the offset to fanotify_info buffer
Date: Mon, 29 Nov 2021 22:15:31 +0200	[thread overview]
Message-ID: <20211129201537.1932819-6-amir73il@gmail.com> (raw)
In-Reply-To: <20211129201537.1932819-1-amir73il@gmail.com>

The fanotify_info buffer contains up to two file handles and a name.
Use macros to simplify the code that access the different items within
the buffer.

Add assertions to verify that stored fh len and name len do not overflow
the u8 stored value in fanotify_info header.

Remove the unused fanotify_info_len() helper.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/notify/fanotify/fanotify.c |  2 +-
 fs/notify/fanotify/fanotify.h | 41 +++++++++++++++++++++++++----------
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 85e542b164c8..ffad224be014 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -411,7 +411,7 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
 	 * be zero in that case if encoding fh len failed.
 	 */
 	err = -ENOENT;
-	if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4))
+	if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4) || fh_len > MAX_HANDLE_SZ)
 		goto out_err;
 
 	/* No external buffer in a variable size allocated fh */
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index d25f500bf7e7..dd23ba659e76 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -49,6 +49,22 @@ struct fanotify_info {
 	 * (optional) file_fh starts at buf[dir_fh_totlen]
 	 * name starts at buf[dir_fh_totlen + file_fh_totlen]
 	 */
+#define FANOTIFY_DIR_FH_SIZE(info)	((info)->dir_fh_totlen)
+#define FANOTIFY_FILE_FH_SIZE(info)	((info)->file_fh_totlen)
+#define FANOTIFY_NAME_SIZE(info)	((info)->name_len + 1)
+
+#define FANOTIFY_DIR_FH_OFFSET(info)	0
+#define FANOTIFY_FILE_FH_OFFSET(info) \
+	(FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info))
+#define FANOTIFY_NAME_OFFSET(info) \
+	(FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info))
+
+#define FANOTIFY_DIR_FH_BUF(info) \
+	((info)->buf + FANOTIFY_DIR_FH_OFFSET(info))
+#define FANOTIFY_FILE_FH_BUF(info) \
+	((info)->buf + FANOTIFY_FILE_FH_OFFSET(info))
+#define FANOTIFY_NAME_BUF(info) \
+	((info)->buf + FANOTIFY_NAME_OFFSET(info))
 } __aligned(4);
 
 static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
@@ -87,7 +103,7 @@ static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *inf
 {
 	BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4);
 
-	return (struct fanotify_fh *)info->buf;
+	return (struct fanotify_fh *)FANOTIFY_DIR_FH_BUF(info);
 }
 
 static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
@@ -101,32 +117,35 @@ static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
 
 static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info)
 {
-	return (struct fanotify_fh *)(info->buf + info->dir_fh_totlen);
+	return (struct fanotify_fh *)FANOTIFY_FILE_FH_BUF(info);
 }
 
-static inline const char *fanotify_info_name(struct fanotify_info *info)
+static inline char *fanotify_info_name(struct fanotify_info *info)
 {
-	return info->buf + info->dir_fh_totlen + info->file_fh_totlen;
+	if (!info->name_len)
+		return NULL;
+
+	return FANOTIFY_NAME_BUF(info);
 }
 
 static inline void fanotify_info_init(struct fanotify_info *info)
 {
+	BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN + MAX_HANDLE_SZ > U8_MAX);
+	BUILD_BUG_ON(NAME_MAX > U8_MAX);
+
 	info->dir_fh_totlen = 0;
 	info->file_fh_totlen = 0;
 	info->name_len = 0;
 }
 
-static inline unsigned int fanotify_info_len(struct fanotify_info *info)
-{
-	return info->dir_fh_totlen + info->file_fh_totlen + info->name_len;
-}
-
 static inline void fanotify_info_copy_name(struct fanotify_info *info,
 					   const struct qstr *name)
 {
+	if (WARN_ON_ONCE(name->len > NAME_MAX))
+		return;
+
 	info->name_len = name->len;
-	strcpy(info->buf + info->dir_fh_totlen + info->file_fh_totlen,
-	       name->name);
+	strcpy(fanotify_info_name(info), name->name);
 }
 
 /*
-- 
2.33.1


  parent reply	other threads:[~2021-11-29 22:52 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-29 20:15 [PATCH v3 00/11] Extend fanotify dirent events Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 01/11] fsnotify: clarify object type argument Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 02/11] fsnotify: separate mark iterator type from object type enum Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 03/11] fanotify: introduce group flag FAN_REPORT_TARGET_FID Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 04/11] fsnotify: generate FS_RENAME event with rich information Amir Goldstein
2021-11-29 20:15 ` Amir Goldstein [this message]
2021-11-29 20:15 ` [PATCH v3 06/11] fanotify: use helpers to parcel fanotify_info buffer Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 07/11] fanotify: support secondary dir fh and name in fanotify_info Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 08/11] fanotify: record old and new parent and name in FAN_RENAME event Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 09/11] fanotify: record either old name new name or both for FAN_RENAME Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 10/11] fanotify: report old and/or new parent+name in FAN_RENAME event Amir Goldstein
2021-11-29 20:15 ` [PATCH v3 11/11] fanotify: wire up " Amir Goldstein
2021-12-15 17:45 ` [PATCH v3 00/11] Extend fanotify dirent events Jan Kara
2021-12-15 18:49   ` Amir Goldstein

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