Bug 216775

Summary:	fanotify reports parent PPID insted of PID for FAN_MODIFY events
Product:	File System	Reporter:	opcoder0 (saikiran.gummaraj)
Component:	ext4	Assignee:	fs_ext4 (fs_ext4)
Status:	RESOLVED INVALID
Severity:	normal	CC:	saikiran.gummaraj
Priority:	P1
Hardware:	Intel
OS:	Linux
Kernel Version:	5.15.0	Subsystem:
Regression:	No	Bisected commit-id:

Description opcoder0 2022-12-05 04:38:02 UTC

Hello,

While I've been developing a library around fanotify in Go, I noticed that fanotify subsystem reports the parent process ID in fanotify_event_metadata.pid instead of the Process ID when mask is set to FAN_MODIFY. I was able to confirm the error through a test and also manually verifying the PIDs in the audit log. I did not observe this behaviour for FAN_ACCESS bit.

I've been able to reproduce this on -

Ubuntu 20.04.5 - 5.15.0-53-generic
Ubuntu 22.10 - 5.19.0-23-generic

It can be reproduced by -

git clone git@github.com:opcoder0/fanotify.git
cd fanotify
sudo go test -v

The test "TestWithCapSysAdmFanotifyFileModified" fails reporting pid mismatch.

Comment 1 Amir Goldstein 2022-12-05 08:45:00 UTC

On Mon, Dec 5, 2022 at 7:02 AM <bugzilla-daemon@kernel.org> wrote:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=216775
>
>             Bug ID: 216775
>            Summary: fanotify reports parent PPID insted of PID for
>                     FAN_MODIFY events
>            Product: File System
>            Version: 2.5
>     Kernel Version: 5.15.0
>           Hardware: Intel
>                 OS: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: ext4
>           Assignee: fs_ext4@kernel-bugs.osdl.org
>           Reporter: saikiran.gummaraj@icloud.com
>         Regression: No
>
> Hello,
>
> While I've been developing a library around fanotify in Go, I noticed that
> fanotify subsystem reports the parent process ID in
> fanotify_event_metadata.pid
> instead of the Process ID when mask is set to FAN_MODIFY. I was able to
> confirm
> the error through a test and also manually verifying the PIDs in the audit
> log.
> I did not observe this behaviour for FAN_ACCESS bit.
>
> I've been able to reproduce this on -
>
> Ubuntu 20.04.5 - 5.15.0-53-generic
> Ubuntu 22.10 - 5.19.0-23-generic
>
> It can be reproduced by -
>
> git clone git@github.com:opcoder0/fanotify.git
> cd fanotify
> sudo go test -v
>
> The test "TestWithCapSysAdmFanotifyFileModified" fails reporting pid
> mismatch.
>

It's a test bug.
The modify event with self pid is generated by os.WriteFile()
Either change test to expect modify event with self pid or move
test file creation before starting the listener.

Thanks,
Amir.

Comment 2 opcoder0 2022-12-05 09:18:58 UTC

Sorry missed that. Thanks a lot!

Comment 3 opcoder0 2022-12-05 09:19:43 UTC

Test issue.