On Tue, Jul 27, 2021 at 11:16:33AM +0300, Amir Goldstein wrote:

On Wed, Jul 21, 2021 at 9:35 AM Amir Goldstein [off-list ref] wrote:

quoted

On Wed, Jul 21, 2021 at 9:18 AM Matthew Bobrowski [off-list ref] wrote:

quoted

The copy_info_records_to_user() helper allows for the separation of
info record copying routines/conditionals from copy_event_to_user(),
which reduces the overall clutter within this function. This becomes
especially true as we start introducing additional info records in the
future i.e. struct fanotify_event_info_pidfd. On success, this helper
returns the total amount of bytes that have been copied into the user
supplied buffer and on error, a negative value is returned to the
caller.

The newly defined macro FANOTIFY_INFO_MODES can be used to obtain info
record types that have been enabled for a specific notification
group. This macro becomes useful in the subsequent patch when the
FAN_REPORT_PIDFD initialization flag is introduced.

Signed-off-by: Matthew Bobrowski <repnop@google.com>

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

quoted

---
 fs/notify/fanotify/fanotify_user.c | 155 ++++++++++++++++-------------
 include/linux/fanotify.h           |   2 +
 2 files changed, 90 insertions(+), 67 deletions(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 182fea255376..d19f70b2c24c 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c

@@ -173,7 +173,7 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
        size_t event_size = FAN_EVENT_METADATA_LEN;
        struct fanotify_event *event = NULL;
        struct fsnotify_event *fsn_event;
-       unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
+       unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);

        pr_debug("%s: group=%p count=%zd\n", __func__, group, count);

@@ -183,8 +183,8 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
                goto out;

        event = FANOTIFY_E(fsn_event);
-       if (fid_mode)
-               event_size += fanotify_event_info_len(fid_mode, event);
+       if (info_mode)
+               event_size += fanotify_event_info_len(info_mode, event);

        if (event_size > count) {
                event = ERR_PTR(-EINVAL);

@@ -401,6 +401,86 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
        return info_len;
 }

+static int copy_info_records_to_user(struct fanotify_event *event,
+                                    struct fanotify_info *info,
+                                    unsigned int info_mode,
+                                    char __user *buf, size_t count)
+{
+       int ret, total_bytes = 0, info_type = 0;
+       unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS;
+
+       /*
+        * Event info records order is as follows: dir fid + name, child fid.
+        */
+       if (fanotify_event_dir_fh_len(event)) {
+               info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
+                                            FAN_EVENT_INFO_TYPE_DFID;
+               ret = copy_fid_info_to_user(fanotify_event_fsid(event),
+                                           fanotify_info_dir_fh(info),
+                                           info_type,
+                                           fanotify_info_name(info),
+                                           info->name_len, buf, count);
+               if (ret < 0)
+                       return ret;
+
+               buf += ret;
+               count -= ret;
+               total_bytes += ret;
+       }
+
+       if (fanotify_event_object_fh_len(event)) {
+               const char *dot = NULL;
+               int dot_len = 0;
+
+               if (fid_mode == FAN_REPORT_FID || info_type) {
+                       /*
+                        * With only group flag FAN_REPORT_FID only type FID is
+                        * reported. Second info record type is always FID.
+                        */
+                       info_type = FAN_EVENT_INFO_TYPE_FID;
+               } else if ((fid_mode & FAN_REPORT_NAME) &&
+                          (event->mask & FAN_ONDIR)) {
+                       /*
+                        * With group flag FAN_REPORT_NAME, if name was not
+                        * recorded in an event on a directory, report the name
+                        * "." with info type DFID_NAME.
+                        */
+                       info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
+                       dot = ".";
+                       dot_len = 1;
+               } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
+                          (event->mask & FAN_ONDIR)) {
+                       /*
+                        * With group flag FAN_REPORT_DIR_FID, a single info
+                        * record has type DFID for directory entry
+                        * modificatio\ n event and for event on a directory.

Just notices this typo in the copied comment:
modificatio\ n

And for the next posting, please remove the mention of fanotify_user.c from
the commit title - it adds no information and clutters the git oneline log.
This concerns patch 3/5 as well. It does NOT concern the kernel/pid.c patches.

Noted.

/M