[PATCH v2 06/16] fanotify: pass optional file access range in pre-content event

Josef Bacik
2024-08-08T19:28:26Z

From: Amir Goldstein <amir73il@gmail.com>

We would like to add file range information to pre-content events.

Pass a struct file_range with optional offset and length to event handler
along with pre-content permission event.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/notify/fanotify/fanotify.c | 10 ++++++++--
fs/notify/fanotify/fanotify.h | 2 ++
include/linux/fsnotify.h | 17 ++++++++++++++++-
include/linux/fsnotify_backend.h | 32 ++++++++++++++++++++++++++++++++
4 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index b163594843f5..4e8dce39fa8f 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -549,9 +549,13 @@ static struct fanotify_event *fanotify_alloc_path_event(const struct path *path,
return &pevent->fae;
}

-static struct fanotify_event *fanotify_alloc_perm_event(const struct path *path,
+static struct fanotify_event *fanotify_alloc_perm_event(const void *data,
+ int data_type,
gfp_t gfp)
{
+ const struct path *path = fsnotify_data_path(data, data_type);
+ const struct file_range *range =
+ fsnotify_data_file_range(data, data_type);
struct fanotify_perm_event *pevent;

pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
@@ -565,6 +569,8 @@ static struct fanotify_event *fanotify_alloc_perm_event(const struct path *path,
pevent->hdr.len = 0;
pevent->state = FAN_EVENT_INIT;
pevent->path = *path;
+ pevent->ppos = range ? range->ppos : NULL;
+ pevent->count = range ? range->count : 0;
path_get(path);

return &pevent->fae;
@@ -802,7 +808,7 @@ static struct fanotify_event *fanotify_alloc_event(
old_memcg = set_active_memcg(group->memcg);

if (fanotify_is_perm_event(mask)) {
- event = fanotify_alloc_perm_event(path, gfp);
+ event = fanotify_alloc_perm_event(data, data_type, gfp);
} else if (fanotify_is_error_event(mask)) {
event = fanotify_alloc_error_event(group, fsid, data,
data_type, &hash);
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index e5ab33cae6a7..93598b7d5952 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -425,6 +425,8 @@ FANOTIFY_PE(struct fanotify_event *event)
struct fanotify_perm_event {
struct fanotify_event fae;
struct path path;
+ const loff_t *ppos; /* optional file range info */
+ size_t count;
u32 response; /* userspace answer to the event */
unsigned short state; /* state of the event */
int fd; /* fd we passed to userspace for this event */
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index a28daf136fea..4609d9b6b087 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -132,6 +132,21 @@ static inline int fsnotify_file(struct file *file, __u32 mask)
}

#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+static inline int fsnotify_file_range(struct file *file, __u32 mask,
+ const loff_t *ppos, size_t count)
+{
+ struct file_range range;
+
+ if (file->f_mode & FMODE_NONOTIFY)
+ return 0;
+
+ range.path = &file->f_path;
+ range.ppos = ppos;
+ range.count = count;
+ return fsnotify_parent(range.path->dentry, mask, &range,
+ FSNOTIFY_EVENT_FILE_RANGE);
+}
+
/*
* fsnotify_file_area_perm - permission hook before access/modify of file range
*/
@@ -175,7 +190,7 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask,
else
return 0;

- return fsnotify_file(file, fsnotify_mask);
+ return fsnotify_file_range(file, fsnotify_mask, ppos, count);
}

/*
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 200a5e3b1cd4..276320846bfd 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -298,6 +298,7 @@ static inline void fsnotify_group_assert_locked(struct fsnotify_group *group)
/* When calling fsnotify tell it if the data is a path or inode */
enum fsnotify_data_type {
FSNOTIFY_EVENT_NONE,
+ FSNOTIFY_EVENT_FILE_RANGE,
FSNOTIFY_EVENT_PATH,
FSNOTIFY_EVENT_INODE,
FSNOTIFY_EVENT_DENTRY,
@@ -310,6 +311,17 @@ struct fs_error_report {
struct super_block *sb;
};

+struct file_range {
+ const struct path *path;
+ const loff_t *ppos;
+ size_t count;
+};
+
+static inline const struct path *file_range_path(const struct file_range *range)
+{
+ return range->path;
+}
+
static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
{
switch (data_type) {
@@ -319,6 +331,8 @@ static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
return d_inode(data);
case FSNOTIFY_EVENT_PATH:
return d_inode(((const struct path *)data)->dentry);
+ case FSNOTIFY_EVENT_FILE_RANGE:
+ return d_inode(file_range_path(data)->dentry);
case FSNOTIFY_EVENT_ERROR:
return ((struct fs_error_report *)data)->inode;
default:
@@ -334,6 +348,8 @@ static inline struct dentry *fsnotify_data_dentry(const void *data, int data_typ
return (struct dentry *)data;
case FSNOTIFY_EVENT_PATH:
return ((const struct path *)data)->dentry;
+ case FSNOTIFY_EVENT_FILE_RANGE:
+ return file_range_path(data)->dentry;
default:
return NULL;
}
@@ -345,6 +361,8 @@ static inline const struct path *fsnotify_data_path(const void *data,
switch (data_type) {
case FSNOTIFY_EVENT_PATH:
return data;
+ case FSNOTIFY_EVENT_FILE_RANGE:
+ return file_range_path(data);
default:
return NULL;
}
@@ -360,6 +378,8 @@ static inline struct super_block *fsnotify_data_sb(const void *data,
return ((struct dentry *)data)->d_sb;
case FSNOTIFY_EVENT_PATH:
return ((const struct path *)data)->dentry->d_sb;
+ case FSNOTIFY_EVENT_FILE_RANGE:
+ return file_range_path(data)->dentry->d_sb;
case FSNOTIFY_EVENT_ERROR:
return ((struct fs_error_report *) data)->sb;
default:
@@ -379,6 +399,18 @@ static inline struct fs_error_report *fsnotify_data_error_report(
}
}

+static inline const struct file_range *fsnotify_data_file_range(
+ const void *data,
+ int data_type)
+{
+ switch (data_type) {
+ case FSNOTIFY_EVENT_FILE_RANGE:
+ return (struct file_range *)data;
+ default:
+ return NULL;
+ }
+}
+
/*
* Index to merged marks iterator array that correlates to a type of watch.
* The type of watched object can be deduced from the iterator type, but not
--
2.43.0