2021-10-15 01:18:58

by Gabriel Krisman Bertazi

Subject: [PATCH v7 14/28] fanotify: Encode empty file handle when no inode is provided

Instead of failing, encode an invalid file handle in fanotify_encode_fh
if no inode is provided. This bogus file handle will be reported by
FAN_FS_ERROR for non-inode errors.

Signed-off-by: Gabriel Krisman Bertazi <[email protected]>

---
Changes since v6:
- Use FILEID_ROOT as the internal value (jan)
- Create an empty FH (jan)

Changes since v5:
- Preserve flags initialization (jan)
- Add BUILD_BUG_ON (amir)
- Require minimum of FANOTIFY_NULL_FH_LEN for fh_len(amir)
- Improve comment to explain the null FH length (jan)
- Simplify logic
---
fs/notify/fanotify/fanotify.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index ec84fee7ad01..c64d61b673ca 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -370,8 +370,14 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
fh->type = FILEID_ROOT;
fh->len = 0;
fh->flags = 0;
+
+ /*
+ * Invalid FHs are used by FAN_FS_ERROR for errors not
+ * linked to any inode. The f_handle won't be reported
+ * back to userspace.
+ */
if (!inode)
- return 0;
+ goto out;

/*
* !gpf means preallocated variable size fh, but fh_len could
@@ -403,6 +409,7 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
fh->type = type;
fh->len = fh_len;

+out:
/*
* Mix fh into event merge key. Hash might be NULL in case of
* unhashed FID events (i.e. FAN_FS_ERROR).
--
2.33.0

2021-10-15 08:23:52

by Amir Goldstein

Subject: Re: [PATCH v7 14/28] fanotify: Encode empty file handle when no inode is provided

On Fri, Oct 15, 2021 at 12:38 AM Gabriel Krisman Bertazi
<[email protected]> wrote:
>
> Instead of failing, encode an invalid file handle in fanotify_encode_fh
> if no inode is provided. This bogus file handle will be reported by
> FAN_FS_ERROR for non-inode errors.
>
> Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
Reviewed-by: Amir Goldstein <[email protected]>

>
> ---
> Changes since v6:
> - Use FILEID_ROOT as the internal value (jan)
> - Create an empty FH (jan)
>
> Changes since v5:
> - Preserve flags initialization (jan)
> - Add BUILD_BUG_ON (amir)
> - Require minimum of FANOTIFY_NULL_FH_LEN for fh_len(amir)
> - Improve comment to explain the null FH length (jan)
> - Simplify logic
> ---
> fs/notify/fanotify/fanotify.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index ec84fee7ad01..c64d61b673ca 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -370,8 +370,14 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
> fh->type = FILEID_ROOT;
> fh->len = 0;
> fh->flags = 0;
> +
> + /*
> + * Invalid FHs are used by FAN_FS_ERROR for errors not
> + * linked to any inode. The f_handle won't be reported
> + * back to userspace.
> + */
> if (!inode)
> - return 0;
> + goto out;
>
> /*
> * !gpf means preallocated variable size fh, but fh_len could
> @@ -403,6 +409,7 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
> fh->type = type;
> fh->len = fh_len;
>
> +out:
> /*
> * Mix fh into event merge key. Hash might be NULL in case of
> * unhashed FID events (i.e. FAN_FS_ERROR).
> --
> 2.33.0
>

2021-10-15 16:16:56

by Jan Kara

Subject: Re: [PATCH v7 14/28] fanotify: Encode empty file handle when no inode is provided

On Thu 14-10-21 18:36:32, Gabriel Krisman Bertazi wrote:
> Instead of failing, encode an invalid file handle in fanotify_encode_fh
> if no inode is provided. This bogus file handle will be reported by
> FAN_FS_ERROR for non-inode errors.
>
> Signed-off-by: Gabriel Krisman Bertazi <[email protected]>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <[email protected]>

Honza

> ---
> Changes since v6:
> - Use FILEID_ROOT as the internal value (jan)
> - Create an empty FH (jan)
>
> Changes since v5:
> - Preserve flags initialization (jan)
> - Add BUILD_BUG_ON (amir)
> - Require minimum of FANOTIFY_NULL_FH_LEN for fh_len(amir)
> - Improve comment to explain the null FH length (jan)
> - Simplify logic
> ---
> fs/notify/fanotify/fanotify.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index ec84fee7ad01..c64d61b673ca 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -370,8 +370,14 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
> fh->type = FILEID_ROOT;
> fh->len = 0;
> fh->flags = 0;
> +
> + /*
> + * Invalid FHs are used by FAN_FS_ERROR for errors not
> + * linked to any inode. The f_handle won't be reported
> + * back to userspace.
> + */
> if (!inode)
> - return 0;
> + goto out;
>
> /*
> * !gpf means preallocated variable size fh, but fh_len could
> @@ -403,6 +409,7 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
> fh->type = type;
> fh->len = fh_len;
>
> +out:
> /*
> * Mix fh into event merge key. Hash might be NULL in case of
> * unhashed FID events (i.e. FAN_FS_ERROR).
> --
> 2.33.0
>
--
Jan Kara <[email protected]>
SUSE Labs, CR