On Fri, Oct 15, 2021 at 12:39 AM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> The error info is a record sent to users on FAN_FS_ERROR events
> documenting the type of error. It also carries an error count,
> documenting how many errors were observed since the last reporting.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
>
> ---
> Changes since v6:
> - Rebase on top of pidfd patches
> Changes since v5:
> - Move error code here
> ---
> fs/notify/fanotify/fanotify.c | 1 +
> fs/notify/fanotify/fanotify.h | 1 +
> fs/notify/fanotify/fanotify_user.c | 35 ++++++++++++++++++++++++++++++
> include/uapi/linux/fanotify.h | 7 ++++++
> 4 files changed, 44 insertions(+)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 8a60c96f5fb2..47e28f418711 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -623,6 +623,7 @@ static struct fanotify_event *fanotify_alloc_error_event(
> return NULL;
>
> fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
> + fee->error = report->error;
> fee->err_count = 1;
> fee->fsid = *fsid;
>
> diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> index b58400926f92..a0897425df07 100644
> --- a/fs/notify/fanotify/fanotify.h
> +++ b/fs/notify/fanotify/fanotify.h
> @@ -199,6 +199,7 @@ FANOTIFY_NE(struct fanotify_event *event)
>
> struct fanotify_error_event {
> struct fanotify_event fae;
> + s32 error; /* Error reported by the Filesystem. */
> u32 err_count; /* Suppressed errors count */
>
> __kernel_fsid_t fsid; /* FSID this error refers to. */
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 39cf8ba4a6ce..8f7c2f4ce674 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -115,6 +115,8 @@ struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
> (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle))
> #define FANOTIFY_PIDFD_INFO_HDR_LEN \
> sizeof(struct fanotify_event_info_pidfd)
> +#define FANOTIFY_ERROR_INFO_LEN \
> + (sizeof(struct fanotify_event_info_error))
>
> static int fanotify_fid_info_len(int fh_len, int name_len)
> {
> @@ -149,6 +151,9 @@ static size_t fanotify_event_len(unsigned int info_mode,
> if (!info_mode)
> return event_len;
>
> + if (fanotify_is_error_event(event->mask))
> + event_len += FANOTIFY_ERROR_INFO_LEN;
> +
> info = fanotify_event_info(event);
> dir_fh_len = fanotify_event_dir_fh_len(event);
> fh_len = fanotify_event_object_fh_len(event);
> @@ -333,6 +338,28 @@ static int process_access_response(struct fsnotify_group *group,
> return -ENOENT;
> }
>
> +static size_t copy_error_info_to_user(struct fanotify_event *event,
> + char __user *buf, int count)
> +{
> + struct fanotify_event_info_error info;
> + struct fanotify_error_event *fee = FANOTIFY_EE(event);
> +
> + info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
> + info.hdr.pad = 0;
> + info.hdr.len = FANOTIFY_ERROR_INFO_LEN;
> +
> + if (WARN_ON(count < info.hdr.len))
> + return -EFAULT;
> +
> + info.error = fee->error;
> + info.error_count = fee->err_count;
> +
> + if (copy_to_user(buf, &info, sizeof(info)))
> + return -EFAULT;
> +
> + return info.hdr.len;
> +}
> +
> static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
> int info_type, const char *name,
> size_t name_len,
> @@ -540,6 +567,14 @@ static int copy_info_records_to_user(struct fanotify_event *event,
> total_bytes += ret;
> }
>
> + if (fanotify_is_error_event(event->mask)) {
> + ret = copy_error_info_to_user(event, buf, count);
> + if (ret < 0)
> + return ret;
> + buf += ret;
> + count -= ret;
> + }
> +
> return total_bytes;
> }
>
> diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
> index 2990731ddc8b..bd1932c2074d 100644
> --- a/include/uapi/linux/fanotify.h
> +++ b/include/uapi/linux/fanotify.h
> @@ -126,6 +126,7 @@ struct fanotify_event_metadata {
> #define FAN_EVENT_INFO_TYPE_DFID_NAME 2
> #define FAN_EVENT_INFO_TYPE_DFID 3
> #define FAN_EVENT_INFO_TYPE_PIDFD 4
> +#define FAN_EVENT_INFO_TYPE_ERROR 5
>
> /* Variable length info record following event metadata */
> struct fanotify_event_info_header {
> @@ -160,6 +161,12 @@ struct fanotify_event_info_pidfd {
> __s32 pidfd;
> };
>
> +struct fanotify_event_info_error {
> + struct fanotify_event_info_header hdr;
> + __s32 error;
> + __u32 error_count;
> +};
> +
> struct fanotify_response {
> __s32 fd;
> __u32 response;
> --
> 2.33.0
>
