For a group with fanotify_init() flag FAN_REPORT_NAME, we report the
parent fid and name for events possible "on child" (e.g. FAN_MODIFY)
in addition to reporting the child fid.
The flag FAN_REPORT_NAME requires the flag FAN_REPORT_FID and there is
a constant for setting both flags named FAN_REPORT_FID_NAME.
The parent fid and name are reported with an info record of type
FAN_EVENT_INFO_TYPE_DFID_NAME, similar to the way that name info is
reported for FAN_DIR_MODIFY events.
The child fid is reported with another info record of type
FAN_EVENT_INFO_TYPE_FID that follows the first info record, with the
same fid info that is reported to a group with FAN_REPORT_FID flag.
Events with name are reported the same way when reported to sb, mount
or inode marks and when reported to a directory watching children.
Events not possible "on child" (e.g. FAN_DELETE_SELF) are reported
with a single FAN_EVENT_INFO_TYPE_FID record, same as they are reported
to a group with FAN_REPORT_FID flag.
If parent is unknown (dentry is disconnected) or parent is not on the
same filesystem as child (dentry is sb root), event is also reported
with a single FAN_EVENT_INFO_TYPE_FID record.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify.c | 25 +++++++++++++++++++++++--
fs/notify/fanotify/fanotify_user.c | 6 +++++-
include/linux/fanotify.h | 2 +-
include/uapi/linux/fanotify.h | 4 ++++
4 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index b651c18d3a93..43c338a8a2f1 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -302,6 +302,8 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
struct inode *id = fanotify_fid_inode(inode, mask, data, data_type);
const struct path *path = fsnotify_data_path(data, data_type);
struct dentry *dentry = fsnotify_data_dentry(data, data_type);
+ struct dentry *parent = NULL;
+ struct name_snapshot child_name;
struct inode *dir = NULL;
/*
@@ -339,17 +341,32 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
/*
* For FAN_DIR_MODIFY event, we report the fid of the directory and
* the name of the modified entry.
+ * With flag FAN_REPORT_NAME, we report the parent fid and name for
+ * events possible "on child" in addition to reporting the child fid.
+ * If parent is unknown (dentry is disconnected) or parent is not on the
+ * same filesystem as child (dentry is sb root), only "child" fid is
+ * reported. Events are reported the same way when reported to sb, mount
+ * or inode marks and when reported to a directory watching children.
* Allocate an fanotify_name_event struct and copy the name.
*/
if (mask & FAN_DIR_MODIFY && !(WARN_ON_ONCE(!file_name))) {
- char *name = NULL;
-
/*
* Make sure that fanotify_event_has_name() is true and that
* fanotify_event_has_fid() is false for FAN_DIR_MODIFY events.
*/
id = NULL;
dir = inode;
+ } else if (FAN_GROUP_FLAG(group, FAN_REPORT_NAME) &&
+ mask & FS_EVENTS_POSS_ON_CHILD &&
+ likely(dentry && !IS_ROOT(dentry))) {
+ parent = dget_parent(dentry);
+ dir = d_inode(parent);
+ take_dentry_name_snapshot(&child_name, dentry);
+ file_name = &child_name.name;
+ }
+ if (dir) {
+ char *name = NULL;
+
if (file_name->len + 1 > FANOTIFY_INLINE_NAME_LEN) {
name = kmalloc(file_name->len + 1, gfp);
if (!name)
@@ -409,6 +426,10 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
event->path.dentry = NULL;
}
out:
+ if (parent) {
+ dput(parent);
+ release_dentry_name_snapshot(&child_name);
+ }
memalloc_unuse_memcg();
return event;
}
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index a1bafc21ebbb..5d369aa5d1bc 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -875,6 +875,10 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
(flags & FANOTIFY_CLASS_BITS) != FAN_CLASS_NOTIF)
return -EINVAL;
+ /* Child name is reported with partent fid */
+ if ((flags & FAN_REPORT_NAME) && !(flags & FAN_REPORT_FID))
+ return -EINVAL;
+
user = get_current_user();
if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
free_uid(user);
@@ -1210,7 +1214,7 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark,
*/
static int __init fanotify_user_setup(void)
{
- BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 8);
+ BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 9);
BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);
fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index 3049a6c06d9e..5412a25c54c0 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -19,7 +19,7 @@
FAN_CLASS_PRE_CONTENT)
#define FANOTIFY_INIT_FLAGS (FANOTIFY_CLASS_BITS | \
- FAN_REPORT_TID | FAN_REPORT_FID | \
+ FAN_REPORT_TID | FAN_REPORT_FID_NAME | \
FAN_CLOEXEC | FAN_NONBLOCK | \
FAN_UNLIMITED_QUEUE | FAN_UNLIMITED_MARKS)
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index 2b56e194b858..04181769bb50 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -54,6 +54,10 @@
/* Flags to determine fanotify event format */
#define FAN_REPORT_TID 0x00000100 /* event->pid is thread id */
#define FAN_REPORT_FID 0x00000200 /* Report unique file id */
+#define FAN_REPORT_NAME 0x00000400 /* Report events with name */
+
+/* Convenience macro - FAN_REPORT_NAME requires FAN_REPORT_FID */
+#define FAN_REPORT_FID_NAME (FAN_REPORT_FID | FAN_REPORT_NAME)
/* Deprecated - do not use this in programs and do not add new flags here! */
#define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK | \
--
2.17.1
