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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 06/11] fanotify: use helpers to parcel fanotify_info buffer
Date: Mon, 29 Nov 2021 22:15:32 +0200	[thread overview]
Message-ID: <20211129201537.1932819-7-amir73il@gmail.com> (raw)
In-Reply-To: <20211129201537.1932819-1-amir73il@gmail.com>

fanotify_info buffer is parceled into variable sized records, so the
records must be written in order: dir_fh, file_fh, name.

Use helpers to assert that order and make fanotify_alloc_name_event()
a bit more generic to allow empty dir_fh record and to allow expanding
to more records (i.e. name2) soon.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/notify/fanotify/fanotify.c | 35 +++++++++++++++++++----------------
 fs/notify/fanotify/fanotify.h | 20 ++++++++++++++++++++
 2 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index ffad224be014..2b13c79cebc6 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -576,7 +576,7 @@ static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id,
 	return &ffe->fae;
 }
 
-static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
+static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir,
 							__kernel_fsid_t *fsid,
 							const struct qstr *name,
 							struct inode *child,
@@ -586,15 +586,17 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
 	struct fanotify_name_event *fne;
 	struct fanotify_info *info;
 	struct fanotify_fh *dfh, *ffh;
-	unsigned int dir_fh_len = fanotify_encode_fh_len(id);
+	unsigned int dir_fh_len = fanotify_encode_fh_len(dir);
 	unsigned int child_fh_len = fanotify_encode_fh_len(child);
-	unsigned int size;
+	unsigned long name_len = name ? name->len : 0;
+	unsigned int len, size;
 
-	size = sizeof(*fne) + FANOTIFY_FH_HDR_LEN + dir_fh_len;
+	/* Reserve terminating null byte even for empty name */
+	size = sizeof(*fne) + name_len + 1;
+	if (dir_fh_len)
+		size += FANOTIFY_FH_HDR_LEN + dir_fh_len;
 	if (child_fh_len)
 		size += FANOTIFY_FH_HDR_LEN + child_fh_len;
-	if (name)
-		size += name->len + 1;
 	fne = kmalloc(size, gfp);
 	if (!fne)
 		return NULL;
@@ -604,22 +606,23 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
 	*hash ^= fanotify_hash_fsid(fsid);
 	info = &fne->info;
 	fanotify_info_init(info);
-	dfh = fanotify_info_dir_fh(info);
-	info->dir_fh_totlen = fanotify_encode_fh(dfh, id, dir_fh_len, hash, 0);
+	if (dir_fh_len) {
+		dfh = fanotify_info_dir_fh(info);
+		len = fanotify_encode_fh(dfh, dir, dir_fh_len, hash, 0);
+		fanotify_info_set_dir_fh(info, len);
+	}
 	if (child_fh_len) {
 		ffh = fanotify_info_file_fh(info);
-		info->file_fh_totlen = fanotify_encode_fh(ffh, child,
-							child_fh_len, hash, 0);
+		len = fanotify_encode_fh(ffh, child, child_fh_len, hash, 0);
+		fanotify_info_set_file_fh(info, len);
 	}
-	if (name) {
-		long salt = name->len;
-
+	if (name_len) {
 		fanotify_info_copy_name(info, name);
-		*hash ^= full_name_hash((void *)salt, name->name, name->len);
+		*hash ^= full_name_hash((void *)name_len, name->name, name_len);
 	}
 
-	pr_debug("%s: ino=%lu size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n",
-		 __func__, id->i_ino, size, dir_fh_len, child_fh_len,
+	pr_debug("%s: size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n",
+		 __func__, size, dir_fh_len, child_fh_len,
 		 info->name_len, info->name_len, fanotify_info_name(info));
 
 	return &fne->fae;
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index dd23ba659e76..7ac6f9f1e414 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -138,6 +138,26 @@ static inline void fanotify_info_init(struct fanotify_info *info)
 	info->name_len = 0;
 }
 
+/* These set/copy helpers MUST be called by order */
+static inline void fanotify_info_set_dir_fh(struct fanotify_info *info,
+					    unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->file_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->name_len > 0))
+		return;
+
+	info->dir_fh_totlen = totlen;
+}
+
+static inline void fanotify_info_set_file_fh(struct fanotify_info *info,
+					     unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->name_len > 0))
+		return;
+
+	info->file_fh_totlen = totlen;
+}
+
 static inline void fanotify_info_copy_name(struct fanotify_info *info,
 					   const struct qstr *name)
 {
-- 
2.33.1


  parent reply	other threads:[~2021-11-29 22:44 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 ` [PATCH v3 05/11] fanotify: use macros to get the offset to fanotify_info buffer Amir Goldstein
2021-11-29 20:15 ` Amir Goldstein [this message]
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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