Hi,
Just some addition to the below comment.
The man page also has this:
RATIONALE top
In a conforming environment, getegid() will always succeed. It is
possible for implementations to provide an extension where a
process in a non-conforming environment will not be associated
with a user or group ID. It is recommended that such
implementations return (gid_t)-1 and set errno to indicate such
an environment; doing so does not violate this standard, since
such an environment is already an extension.
I'm not sure what kind of a better message users would like to have in case the
(gid_t)-1 is returned.
Current message is pretty good providing this returned value which helps to
identify problem.
Thanks,
Serguei
On 1/7/22, 4:05 AM, "serviceability-dev on behalf of Baesken, Matthias"
<serviceability-dev-r...@openjdk.java.net on behalf of
matthias.baes...@sap.com> wrote:
Hi, the manpage of getegid
https://man7.org/linux/man-pages/man3/getegid.3p.html
says : " The getegid() function shall always be successful and no return
value is reserved to indicate an error."
So I am not sure what kind of additional check or error message you would
expect ?
> In this case, the exception message is clear that the gid is -1 so it
should help with debugging the issue.
Yes , the message gives already some info, that's good (or better than
nothing at least).
Best regards, Matthias
-----Original Message-----
From: jdk-dev <jdk-dev-r...@openjdk.java.net> On Behalf Of Alan Bateman
Sent: Freitag, 7. Januar 2022 12:48
To: stuart nelson <h...@stuartnelson.xyz>; jdk-...@openjdk.java.net
Subject: Re: [libattach] misleading error message when checking gid fails
On 07/01/2022 11:33, stuart nelson wrote:
> Hey,
>
> First, apologies if this should be directed to a different mailing list,
I didn't find one that seemed correct in the mailing lists
(https://mail.openjdk.java.net/mailman/listinfo).
>
> I was building up a syscall filters list for a java process for seccomp,
when I encountered this error stack trace:
>
> (elided)
> Caused by: java.io.IOException: well-known file
/proc/1974261/root/tmp/.java_pid1974261 is not secure: file's group should be
the current group (which is -1) but the group is 1000
> at
jdk.attach/sun.tools.attach.VirtualMachineImpl.checkPermissions(Native Method)
> at
jdk.attach/sun.tools.attach.VirtualMachineImpl.<init>(VirtualMachineImpl.java:112)
> at
jdk.attach/sun.tools.attach.AttachProviderImpl.attachVirtualMachine(AttachProviderImpl.java:58)
> at
jdk.attach/com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:207)
> ... 6 more
>
> The error originates from this line:
>
https://hg.openjdk.java.net/jdk/jdk/file/ee1d592a9f53/src/jdk.attach/linux/native/libattach/VirtualMachineImpl.c#l167
>
> The value for gid is found on this line:
>
https://hg.openjdk.java.net/jdk/jdk/file/ee1d592a9f53/src/jdk.attach/linux/native/libattach/VirtualMachineImpl.c#l150
>
> The reason getegid() returns -1 is because it wasn't in my allowed
syscalls list for seccomp, so EPERM (-1) was returned instead.
>
> My question is: -1 is an invalid gid. Should this be checked in the code,
and a more helpful error message returned? It could definitely save future
developers time.
>
serviceability-dev is the mailing lists for the Attach API. In this
case, the exception message is clear that the gid is -1 so it should
help with debugging the issue.
-Alan
