From: Amir Goldstein <amir73il@xxxxxxxxx>
Generate pre-content event on open in addition to FS_OPEN_PERM,
but without sb_writers held and after file was truncated
in case file was opened with O_CREAT and/or O_TRUNC.
The event will have a range info of [0..0] to provide an opportunity
to fill entire file content on open.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/namei.c | 10 +++++++++-
include/linux/fsnotify.h | 4 +++-
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 4a4a22a08ac2..b49fb1f80c0c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3782,7 +3782,15 @@ static int do_open(struct nameidata *nd,
}
if (do_truncate)
mnt_drop_write(nd->path.mnt);
- return error;
+ if (error)
+ return error;
+
+ /*
+ * This permission hook is different than fsnotify_open_perm() hook.
+ * This is a pre-content hook that is called without sb_writers held
+ * and after the file was truncated.
+ */
+ return fsnotify_file_area_perm(file, MAY_OPEN, &file->f_pos, 0);
}
/**
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 22150e5797c5..1e87a54b88b6 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -171,6 +171,8 @@ static inline int fsnotify_pre_content(const struct file *file,
/*
* fsnotify_file_area_perm - permission hook before access of file range
+ *
+ * Called post open with access range [0..0].
*/
static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
const loff_t *ppos, size_t count)
@@ -185,7 +187,7 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
/*
* read()/write and other types of access generate pre-content events.
*/
- if (perm_mask & (MAY_READ | MAY_WRITE | MAY_ACCESS)) {
+ if (perm_mask & (MAY_READ | MAY_WRITE | MAY_ACCESS | MAY_OPEN)) {
int ret = fsnotify_pre_content(file, ppos, count);
if (ret)
--
2.43.0
