On Wed, Jul 21, 2021 at 9:18 AM Matthew Bobrowski <repnop@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> 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.
> + */
> + 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 (ret < 0)
> - goto out_close_fd;
> -
> - 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 (info_mode) {
> + ret = copy_info_records_to_user(event, info, info_mode,
> + buf, count);
> if (ret < 0)
> goto out_close_fd;
> -
> - 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.
> --
> 2.32.0.432.gabb21c7263-goog
>
> /M
