Re: [PATCH v8 29/32] fanotify: Allow users to request FAN_FS_ERROR events

From: Jan Kara <jack@suse.cz>
To: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: jack@suse.com, amir73il@gmail.com, djwong@kernel.org,
	tytso@mit.edu, david@fromorbit.com, dhowells@redhat.com,
	khazhy@google.com, linux-fsdevel@vger.kernel.org,
	linux-ext4@vger.kernel.org, linux-api@vger.kernel.org,
	kernel@collabora.com
Subject: Re: [PATCH v8 29/32] fanotify: Allow users to request FAN_FS_ERROR events
Date: Tue, 19 Oct 2021 17:24:09 +0200	[thread overview]
Message-ID: <20211019152409.GQ3255@quack2.suse.cz> (raw)
In-Reply-To: <20211019000015.1666608-30-krisman@collabora.com>

On Mon 18-10-21 21:00:12, Gabriel Krisman Bertazi wrote:
> Wire up the FAN_FS_ERROR event in the fanotify_mark syscall, allowing
> user space to request the monitoring of FAN_FS_ERROR events.
> 
> These events are limited to filesystem marks, so check it is the
> case in the syscall handler.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> 
> ---
> Changes since v7:
>   - Move the verification closer to similar code (Amir)
> ---
>  fs/notify/fanotify/fanotify.c      | 2 +-
>  fs/notify/fanotify/fanotify_user.c | 4 ++++
>  include/linux/fanotify.h           | 6 +++++-
>  3 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 0f6694eadb63..20169b8d5ab7 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -821,7 +821,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
>  	BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
>  	BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);
>  
> -	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
> +	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);
>  
>  	mask = fanotify_group_event_mask(group, iter_info, mask, data,
>  					 data_type, dir);
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index b83c61c934d0..22dca806c7e2 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -1535,6 +1535,10 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
>  	    group->priority == FS_PRIO_0)
>  		goto fput_and_out;
>  
> +	if (mask & FAN_FS_ERROR &&
> +	    mark_type != FAN_MARK_FILESYSTEM)
> +		goto fput_and_out;
> +
>  	/*
>  	 * Events that do not carry enough information to report
>  	 * event->fd require a group that supports reporting fid.  Those
> diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
> index 52d464802d99..616af2ea20f3 100644
> --- a/include/linux/fanotify.h
> +++ b/include/linux/fanotify.h
> @@ -91,9 +91,13 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
>  #define FANOTIFY_INODE_EVENTS	(FANOTIFY_DIRENT_EVENTS | \
>  				 FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
>  
> +/* Events that can only be reported with data type FSNOTIFY_EVENT_ERROR */
> +#define FANOTIFY_ERROR_EVENTS	(FAN_FS_ERROR)
> +
>  /* Events that user can request to be notified on */
>  #define FANOTIFY_EVENTS		(FANOTIFY_PATH_EVENTS | \
> -				 FANOTIFY_INODE_EVENTS)
> +				 FANOTIFY_INODE_EVENTS | \
> +				 FANOTIFY_ERROR_EVENTS)
>  
>  /* Events that require a permission response from user */
>  #define FANOTIFY_PERM_EVENTS	(FAN_OPEN_PERM | FAN_ACCESS_PERM | \
> -- 
> 2.33.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR