fanotify: support secondary dir fh and name in fanotify_info

Allow storing a secondary dir fh and name tupple in fanotify_info.
This will be used to store the new parent and name information in
FAN_RENAME event.

Link: https://lore.kernel.org/r/20211129201537.1932819-8-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

3 files changed, 88 insertions, 14 deletions

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 2b13c79cebc6..5f184b2d6ea7 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -76,8 +76,10 @@ static bool fanotify_info_equal(struct fanotify_info *info1,
 				struct fanotify_info *info2)
 {
 	if (info1->dir_fh_totlen != info2->dir_fh_totlen ||
+	    info1->dir2_fh_totlen != info2->dir2_fh_totlen ||
 	    info1->file_fh_totlen != info2->file_fh_totlen ||
-	    info1->name_len != info2->name_len)
+	    info1->name_len != info2->name_len ||
+	    info1->name2_len != info2->name2_len)
 		return false;
 
 	if (info1->dir_fh_totlen &&
@@ -85,14 +87,24 @@ static bool fanotify_info_equal(struct fanotify_info *info1,
 			       fanotify_info_dir_fh(info2)))
 		return false;
 
+	if (info1->dir2_fh_totlen &&
+	    !fanotify_fh_equal(fanotify_info_dir2_fh(info1),
+			       fanotify_info_dir2_fh(info2)))
+		return false;
+
 	if (info1->file_fh_totlen &&
 	    !fanotify_fh_equal(fanotify_info_file_fh(info1),
 			       fanotify_info_file_fh(info2)))
 		return false;
 
-	return !info1->name_len ||
-		!memcmp(fanotify_info_name(info1), fanotify_info_name(info2),
-			info1->name_len);
+	if (info1->name_len &&
+	    memcmp(fanotify_info_name(info1), fanotify_info_name(info2),
+		   info1->name_len))
+		return false;
+
+	return !info1->name2_len ||
+		!memcmp(fanotify_info_name2(info1), fanotify_info_name2(info2),
+			info1->name2_len);
 }
 
 static bool fanotify_name_event_equal(struct fanotify_name_event *fne1,
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 7ac6f9f1e414..8fa3bc0effd4 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -40,31 +40,45 @@ struct fanotify_fh {
 struct fanotify_info {
 	/* size of dir_fh/file_fh including fanotify_fh hdr size */
 	u8 dir_fh_totlen;
+	u8 dir2_fh_totlen;
 	u8 file_fh_totlen;
 	u8 name_len;
-	u8 pad;
+	u8 name2_len;
+	u8 pad[3];
 	unsigned char buf[];
 	/*
 	 * (struct fanotify_fh) dir_fh starts at buf[0]
-	 * (optional) file_fh starts at buf[dir_fh_totlen]
-	 * name starts at buf[dir_fh_totlen + file_fh_totlen]
+	 * (optional) dir2_fh starts at buf[dir_fh_totlen]
+	 * (optional) file_fh starts at buf[dir_fh_totlen + dir2_fh_totlen]
+	 * name starts at buf[dir_fh_totlen + dir2_fh_totlen + file_fh_totlen]
+	 * ...
 	 */
 #define FANOTIFY_DIR_FH_SIZE(info)	((info)->dir_fh_totlen)
+#define FANOTIFY_DIR2_FH_SIZE(info)	((info)->dir2_fh_totlen)
 #define FANOTIFY_FILE_FH_SIZE(info)	((info)->file_fh_totlen)
 #define FANOTIFY_NAME_SIZE(info)	((info)->name_len + 1)
+#define FANOTIFY_NAME2_SIZE(info)	((info)->name2_len + 1)
 
 #define FANOTIFY_DIR_FH_OFFSET(info)	0
-#define FANOTIFY_FILE_FH_OFFSET(info) \
+#define FANOTIFY_DIR2_FH_OFFSET(info) \
 	(FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info))
+#define FANOTIFY_FILE_FH_OFFSET(info) \
+	(FANOTIFY_DIR2_FH_OFFSET(info) + FANOTIFY_DIR2_FH_SIZE(info))
 #define FANOTIFY_NAME_OFFSET(info) \
 	(FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info))
+#define FANOTIFY_NAME2_OFFSET(info) \
+	(FANOTIFY_NAME_OFFSET(info) + FANOTIFY_NAME_SIZE(info))
 
 #define FANOTIFY_DIR_FH_BUF(info) \
 	((info)->buf + FANOTIFY_DIR_FH_OFFSET(info))
+#define FANOTIFY_DIR2_FH_BUF(info) \
+	((info)->buf + FANOTIFY_DIR2_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))
+#define FANOTIFY_NAME2_BUF(info) \
+	((info)->buf + FANOTIFY_NAME2_OFFSET(info))
 } __aligned(4);
 
 static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
@@ -106,6 +120,20 @@ static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *inf
 	return (struct fanotify_fh *)FANOTIFY_DIR_FH_BUF(info);
 }
 
+static inline int fanotify_info_dir2_fh_len(struct fanotify_info *info)
+{
+	if (!info->dir2_fh_totlen ||
+	    WARN_ON_ONCE(info->dir2_fh_totlen < FANOTIFY_FH_HDR_LEN))
+		return 0;
+
+	return info->dir2_fh_totlen - FANOTIFY_FH_HDR_LEN;
+}
+
+static inline struct fanotify_fh *fanotify_info_dir2_fh(struct fanotify_info *info)
+{
+	return (struct fanotify_fh *)FANOTIFY_DIR2_FH_BUF(info);
+}
+
 static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
 {
 	if (!info->file_fh_totlen ||
@@ -128,31 +156,55 @@ static inline char *fanotify_info_name(struct fanotify_info *info)
 	return FANOTIFY_NAME_BUF(info);
 }
 
+static inline char *fanotify_info_name2(struct fanotify_info *info)
+{
+	if (!info->name2_len)
+		return NULL;
+
+	return FANOTIFY_NAME2_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->dir2_fh_totlen = 0;
 	info->file_fh_totlen = 0;
 	info->name_len = 0;
+	info->name2_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))
+	if (WARN_ON_ONCE(info->dir2_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->file_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
 		return;
 
 	info->dir_fh_totlen = totlen;
 }
 
+static inline void fanotify_info_set_dir2_fh(struct fanotify_info *info,
+					     unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->file_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->dir2_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))
+	if (WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
 		return;
 
 	info->file_fh_totlen = totlen;
@@ -161,13 +213,24 @@ static inline void fanotify_info_set_file_fh(struct fanotify_info *info,
 static inline void fanotify_info_copy_name(struct fanotify_info *info,
 					   const struct qstr *name)
 {
-	if (WARN_ON_ONCE(name->len > NAME_MAX))
+	if (WARN_ON_ONCE(name->len > NAME_MAX) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
 		return;
 
 	info->name_len = name->len;
 	strcpy(fanotify_info_name(info), name->name);
 }
 
+static inline void fanotify_info_copy_name2(struct fanotify_info *info,
+					    const struct qstr *name)
+{
+	if (WARN_ON_ONCE(name->len > NAME_MAX))
+		return;
+
+	info->name2_len = name->len;
+	strcpy(fanotify_info_name2(info), name->name);
+}
+
 /*
  * Common structure for fanotify events. Concrete structs are allocated in
  * fanotify_handle_event() and freed when the information is retrieved by
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 00bbc29712bb..e4a11f56782d 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -332,11 +332,10 @@ static int process_access_response(struct fsnotify_group *group,
 static size_t copy_error_info_to_user(struct fanotify_event *event,
 				      char __user *buf, int count)
 {
-	struct fanotify_event_info_error info;
+	struct fanotify_event_info_error info = { };
 	struct fanotify_error_event *fee = FANOTIFY_EE(event);
 
 	info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
-	info.hdr.pad = 0;
 	info.hdr.len = FANOTIFY_ERROR_INFO_LEN;
 
 	if (WARN_ON(count < info.hdr.len))