With group flag FAN_REPORT_FID, we do not store event->path.
Instead, we will store the file handle and fsid in event->info.fid.
Because event->info and event->path share the same union space, set
bit 0 of event->info.flags, so we know how to free and compare the
event objects.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify.c | 35 ++++++++++++++++++++++++------
fs/notify/fanotify/fanotify.h | 27 +++++++++++++++++++++++
fs/notify/fanotify/fanotify_user.c | 3 +++
3 files changed, 58 insertions(+), 7 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 59d093923c97..8192d4b1db21 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -25,11 +25,16 @@ static bool should_merge(struct fsnotify_event *old_fsn,
old = FANOTIFY_E(old_fsn);
new = FANOTIFY_E(new_fsn);
- if (old_fsn->inode == new_fsn->inode && old->pid == new->pid &&
- old->path.mnt == new->path.mnt &&
- old->path.dentry == new->path.dentry)
- return true;
- return false;
+ if (old_fsn->inode != new_fsn->inode || old->pid != new->pid)
+ return false;
+
+ if (FANOTIFY_HAS_FID(new)) {
+ return FANOTIFY_HAS_FID(old) &&
+ fanotify_fid_equal(old->info.fid, new->info.fid);
+ } else {
+ return old->path.mnt == new->path.mnt &&
+ old->path.dentry == new->path.dentry;
+ }
}
/* and the list better be locked by something too! */
@@ -178,7 +183,10 @@ init: __maybe_unused
event->pid = get_pid(task_pid(current));
else
event->pid = get_pid(task_tgid(current));
- if (path && !FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
+ if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
+ /* TODO: allocate buffer and encode file handle */
+ fanotify_set_fid(event, NULL);
+ } else if (path) {
event->path = *path;
path_get(&event->path);
} else {
@@ -277,8 +285,21 @@ static void fanotify_free_event(struct fsnotify_event *fsn_event)
{
struct fanotify_event *event;
+ /*
+ * event->path and event->info are a union. Make sure that
+ * event->info.flags overlaps with path.dentry pointer, so it is safe
+ * to use bit 0 to classify the event info type (FANOTIFY_HAS_FID).
+ */
+ BUILD_BUG_ON(offsetof(struct fanotify_event, path.dentry) !=
+ offsetof(struct fanotify_event, info.flags));
+ BUILD_BUG_ON(!__builtin_types_compatible_p(typeof(event->info.flags),
+ unsigned long));
+
event = FANOTIFY_E(fsn_event);
- path_put(&event->path);
+ if (FANOTIFY_HAS_FID(event))
+ kfree(event->info.fid);
+ else
+ path_put(&event->path);
put_pid(event->pid);
if (fanotify_is_perm_event(fsn_event->mask)) {
kmem_cache_free(fanotify_perm_event_cachep,
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 2e4fca30afda..d6ed31134321 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -13,8 +13,20 @@ extern struct kmem_cache *fanotify_perm_event_cachep;
struct fanotify_info {
struct fanotify_event_fid *fid;
+ unsigned long flags;
};
+static inline bool fanotify_fid_equal(const struct fanotify_event_fid *fid1,
+ const struct fanotify_event_fid *fid2)
+{
+ if (fid1 == fid2)
+ return true;
+
+ return fid1 && fid2 && fid1->handle_bytes == fid2->handle_bytes &&
+ !memcmp((void *)fid1, (void *)fid2,
+ FANOTIFY_FID_LEN(fid1->handle_bytes));
+}
+
/*
* Structure for normal fanotify events. It gets allocated in
* fanotify_handle_event() and freed when the information is retrieved by
@@ -38,6 +50,21 @@ struct fanotify_event {
struct pid *pid;
};
+/*
+ * Bit 0 of info.flags is set when event has fid information.
+ * event->info shares the same union address with event->path, so this helps
+ * us tell if event has fid or path.
+ */
+#define __FANOTIFY_FID 1UL
+#define FANOTIFY_HAS_FID(event) ((event)->info.flags & __FANOTIFY_FID)
+
+static inline void fanotify_set_fid(struct fanotify_event *event,
+ struct fanotify_event_fid *fid)
+{
+ event->info.fid = fid;
+ event->info.flags = fid ? __FANOTIFY_FID : 0;
+}
+
/*
* Structure for permission fanotify events. It gets allocated and freed in
* fanotify_handle_event() since we wait there for user response. When the
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 93e1aa2a389f..29f61060af66 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -81,6 +81,9 @@ static int create_fd(struct fsnotify_group *group,
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+ if (WARN_ON_ONCE(FANOTIFY_HAS_FID(event)))
+ return -EBADF;
+
client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
if (client_fd < 0)
return client_fd;
--
2.17.1
