[PATCH v5 08/18] fanotify: report file range info with pre-content events

Josef Bacik
2024-09-04T20:29:28Z

From: Amir Goldstein <amir73il@gmail.com>

With group class FAN_CLASS_PRE_CONTENT, report offset and length info
along with FAN_PRE_ACCESS and FAN_PRE_MODIFY permission events.

This information is meant to be used by hierarchical storage managers
that want to fill partial content of files on first access to range.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/notify/fanotify/fanotify.h | 8 +++++++
fs/notify/fanotify/fanotify_user.c | 38 ++++++++++++++++++++++++++++++
include/uapi/linux/fanotify.h | 8 +++++++
3 files changed, 54 insertions(+)

diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 93598b7d5952..7f06355afa1f 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -448,6 +448,14 @@ static inline bool fanotify_is_perm_event(u32 mask)
mask & FANOTIFY_PERM_EVENTS;
}

+static inline bool fanotify_event_has_access_range(struct fanotify_event *event)
+{
+ if (!(event->mask & FANOTIFY_PRE_CONTENT_EVENTS))
+ return false;
+
+ return FANOTIFY_PERM(event)->ppos;
+}
+
static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
{
return container_of(fse, struct fanotify_event, fse);
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 5ece186d5c50..ed56fe6f5ec7 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -123,6 +123,8 @@ struct kmem_cache *fanotify_perm_event_cachep __ro_after_init;
sizeof(struct fanotify_event_info_pidfd)
#define FANOTIFY_ERROR_INFO_LEN \
(sizeof(struct fanotify_event_info_error))
+#define FANOTIFY_RANGE_INFO_LEN \
+ (sizeof(struct fanotify_event_info_range))

static int fanotify_fid_info_len(int fh_len, int name_len)
{
@@ -182,6 +184,9 @@ static size_t fanotify_event_len(unsigned int info_mode,
if (info_mode & FAN_REPORT_PIDFD)
event_len += FANOTIFY_PIDFD_INFO_LEN;

+ if (fanotify_event_has_access_range(event))
+ event_len += FANOTIFY_RANGE_INFO_LEN;
+
return event_len;
}

@@ -526,6 +531,30 @@ static int copy_pidfd_info_to_user(int pidfd,
return info_len;
}

+static size_t copy_range_info_to_user(struct fanotify_event *event,
+ char __user *buf, int count)
+{
+ struct fanotify_perm_event *pevent = FANOTIFY_PERM(event);
+ struct fanotify_event_info_range info = { };
+ size_t info_len = FANOTIFY_RANGE_INFO_LEN;
+
+ if (WARN_ON_ONCE(info_len > count))
+ return -EFAULT;
+
+ if (WARN_ON_ONCE(!pevent->ppos))
+ return -EINVAL;
+
+ info.hdr.info_type = FAN_EVENT_INFO_TYPE_RANGE;
+ info.hdr.len = info_len;
+ info.offset = *(pevent->ppos);
+ info.count = pevent->count;
+
+ if (copy_to_user(buf, &info, info_len))
+ return -EFAULT;
+
+ return info_len;
+}
+
static int copy_info_records_to_user(struct fanotify_event *event,
struct fanotify_info *info,
unsigned int info_mode, int pidfd,
@@ -647,6 +676,15 @@ static int copy_info_records_to_user(struct fanotify_event *event,
total_bytes += ret;
}

+ if (fanotify_event_has_access_range(event)) {
+ ret = copy_range_info_to_user(event, buf, count);
+ if (ret < 0)
+ return ret;
+ buf += ret;
+ count -= ret;
+ total_bytes += ret;
+ }
+
return total_bytes;
}

diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index ac00fad66416..6136e8a9f9f3 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -145,6 +145,7 @@ struct fanotify_event_metadata {
#define FAN_EVENT_INFO_TYPE_DFID 3
#define FAN_EVENT_INFO_TYPE_PIDFD 4
#define FAN_EVENT_INFO_TYPE_ERROR 5
+#define FAN_EVENT_INFO_TYPE_RANGE 6

/* Special info types for FAN_RENAME */
#define FAN_EVENT_INFO_TYPE_OLD_DFID_NAME 10
@@ -191,6 +192,13 @@ struct fanotify_event_info_error {
__u32 error_count;
};

+struct fanotify_event_info_range {
+ struct fanotify_event_info_header hdr;
+ __u32 pad;
+ __u64 offset;
+ __u64 count;
+};
+
/*
* User space may need to record additional information about its decision.
* The extra information type records what kind of information is included.
--
2.43.0