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 initialisation flag is introduced.
Signed-off-by: Matthew Bobrowski <repnop@xxxxxxxxxx>
---
Changes since v1:
* Renamed the new helper from copy_info_to_user() to
copy_info_records_to_user().
* From the copy_info_records_to_user() helper, the total number of
bytes that were copied to the user supplied buffer are returned,
rather than only returning the number of bytes copied in the last
call to copy_to_user().
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 6223ffd0e4db..85d6eea8d45d 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.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_DFID;
+ } else {
+ /*
+ * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
+ * a single info record has type FID for event on a
+ * non-directory, when there is no directory to report.
+ * For example, on FAN_DELETE_SELF event.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_FID;
+ }
+
+ ret = copy_fid_info_to_user(fanotify_event_fsid(event),
+ fanotify_event_object_fh(event),
+ info_type, dot, dot_len,
+ buf, count);
+ if (ret < 0)
+ return ret;
+
+ buf += ret;
+ count -= ret;
+ total_bytes += ret;
+ }
+
+ return total_bytes;
+}
+
static ssize_t copy_event_to_user(struct fsnotify_group *group,
struct fanotify_event *event,
char __user *buf, size_t count)
@@ -408,15 +488,14 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
struct fanotify_event_metadata metadata;
struct path *path = fanotify_event_path(event);
struct fanotify_info *info = fanotify_event_info(event);
- unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
+ unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
struct file *f = NULL;
int ret, fd = FAN_NOFD;
- int info_type = 0;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
metadata.event_len = FAN_EVENT_METADATA_LEN +
- fanotify_event_info_len(fid_mode, event);
+ fanotify_event_info_len(info_mode, event);
metadata.metadata_len = FAN_EVENT_METADATA_LEN;
metadata.vers = FANOTIFY_METADATA_VERSION;
metadata.reserved = 0;
@@ -465,69 +544,11 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
if (f)
fd_install(fd, f);
- /* Event info records order is: 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 (info_mode) {
+ ret = copy_info_records_to_user(event, info, info_mode,
+ buf, count);
if (ret < 0)
return ret;
-
- buf += ret;
- count -= 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 modification
- * event and for event on a directory.
- */
- info_type = FAN_EVENT_INFO_TYPE_DFID;
- } else {
- /*
- * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
- * a single info record has type FID for event on a
- * non-directory, when there is no directory to report.
- * For example, on FAN_DELETE_SELF event.
- */
- info_type = FAN_EVENT_INFO_TYPE_FID;
- }
-
- ret = copy_fid_info_to_user(fanotify_event_fsid(event),
- fanotify_event_object_fh(event),
- info_type, dot, dot_len,
- buf, count);
- if (ret < 0)
- return ret;
-
- buf += ret;
- count -= ret;
}
return metadata.event_len;
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index a16dbeced152..10a7e26ddba6 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -27,6 +27,8 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
#define FANOTIFY_FID_BITS (FAN_REPORT_FID | FAN_REPORT_DFID_NAME)
+#define FANOTIFY_INFO_MODES (FANOTIFY_FID_BITS)
+
/*
* fanotify_init() flags that require CAP_SYS_ADMIN.
* We do not allow unprivileged groups to request permission events.
--
2.30.2
/M
