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References: <20210812214010.3197279-1-krisman@collabora.com> <20210812214010.3197279-14-krisman@collabora.com>
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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Fri, 13 Aug 2021 11:28:58 +0300
Message-ID: <CAOQ4uxjQ_pFxzr00woh+eqcY2p-=L6tdBnuepg-=WKYGUWUqDQ@mail.gmail.com>
Subject: Re: [PATCH v6 13/21] fanotify: Require fid_mode for any non-fd event
To:     Gabriel Krisman Bertazi <krisman@collabora.com>
Cc:     Jan Kara <jack@suse.com>, Linux API <linux-api@vger.kernel.org>,
        Ext4 <linux-ext4@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Khazhismel Kumykov <khazhy@google.com>,
        David Howells <dhowells@redhat.com>,
        Dave Chinner <david@fromorbit.com>,
        Theodore Tso <tytso@mit.edu>,
        "Darrick J. Wong" <djwong@kernel.org>,
        Matthew Bobrowski <repnop@google.com>, kernel@collabora.com,
        Jan Kara <jack@suse.cz>
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On Fri, Aug 13, 2021 at 12:41 AM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> Like inode events, FAN_FS_ERROR will require fid mode.  Therefore,
> convert the verification during fanotify_mark(2) to require fid for any
> non-fd event.  This means fid_mode will not only be required for inode
> events, but for any event that doesn't provide a descriptor.
>
> Suggested-by: Amir Goldstein <amir73il@gmail.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

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

>
> ---
> changes since v5:
>   - Fix condition to include FANOTIFY_EVENT_FLAGS. (me)
>   - Fix comment identation  (jan)
> ---
>  fs/notify/fanotify/fanotify_user.c | 12 ++++++------
>  include/linux/fanotify.h           |  3 +++
>  2 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 4cacea5fcaca..54107f1533d5 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -1387,14 +1387,14 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
>                 goto fput_and_out;
>
>         /*
> -        * Events with data type inode do not carry enough information to report
> -        * event->fd, so we do not allow setting a mask for inode events unless
> -        * group supports reporting fid.
> -        * inode events are not supported on a mount mark, because they do not
> -        * carry enough information (i.e. path) to be filtered by mount point.
> +        * Events that do not carry enough information to report
> +        * event->fd require a group that supports reporting fid.  Those
> +        * events are not supported on a mount mark, because they do not
> +        * carry enough information (i.e. path) to be filtered by mount
> +        * point.
>          */
>         fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
> -       if (mask & FANOTIFY_INODE_EVENTS &&
> +       if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_EVENT_FLAGS) &&
>             (!fid_mode || mark_type == FAN_MARK_MOUNT))
>                 goto fput_and_out;
>
> diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
> index a16dbeced152..c05d45bde8b8 100644
> --- a/include/linux/fanotify.h
> +++ b/include/linux/fanotify.h
> @@ -81,6 +81,9 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
>   */
>  #define FANOTIFY_DIRENT_EVENTS (FAN_MOVE | FAN_CREATE | FAN_DELETE)
>
> +/* Events that can be reported with event->fd */
> +#define FANOTIFY_FD_EVENTS (FANOTIFY_PATH_EVENTS | FANOTIFY_PERM_EVENTS)
> +
>  /* Events that can only be reported with data type FSNOTIFY_EVENT_INODE */
>  #define FANOTIFY_INODE_EVENTS  (FANOTIFY_DIRENT_EVENTS | \
>                                  FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
> --
> 2.32.0
>