Ubuntu 25.10 - access denied to /tmp even in 777 mode without protected mode

[Tusenka]

Ubuntu 25.10 - access denied to /tmp even in 777 mode without protected mode

Description:

Java returns access denied to /tmp despite:

1777 mode for permissions
Without sticky bit on /tmp
Without protected folder mode

Steps to reproduce:

Run and app with access required to /tmp, i.e., pyspark from non-root user.

Error:

26/03/28 14:15:17 WARN Utils: Set SPARK_LOCAL_IP if you need to bind to another address
Using Spark's default log4j profile: org/apache/spark/log4j2-defaults.properties
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
Exception in thread "main" java.nio.file.AccessDeniedException: /tmp/tmppqkak67g/connection12539062633467823222.info

Environment:

Ubuntu 25.10
Python 3.13

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 25.10
Release: 25.10
Codename: questing

(.venv) cas12@cas12-System-Product-Name:~/vscode/data-algorithms-with-spark$ df -h /tmp
Filesystem      Size  Used Avail Use% Mounted on
/dev/nvme0n1p5  9.1G  358M  8.3G   5% /tmp

(.venv) cas12@cas12-System-Product-Name:~/vscode/data-algorithms-with-spark$ ls -ld /tmp
drwxrwxrwt 349 root root 974848 Mar 28 14:10 /tmp

(.venv) cas12@cas12-System-Product-Name:~/vscode/data-algorithms-with-spark$ sudo sysctl fs.protected_regular=0
fs.protected_regular = 0

copy of issue for ubuntu 25.10 https://unix.stackexchange.com/questions/805192/ubuntu-25-10-access-denied-to-tmp-even-in-777-mode-without-protected-mode
From the answer it looks like the system create dir without permissions.

[azmatsiddique]

Hey @Tusenka
This doesn’t look like a /tmp permission issue (/tmp is correctly 1777, and fs.protected_regular=0).
suggests the parent dir is created with restrictive permissions (likely 0700, e.g. via Python tempfile), and then accessed by the JVM, causing java.nio.file.AccessDeniedException.
So this appears to be a cross-runtime temp dir permission mismatch (Python → JVM), not a /tmp mount issue.
Workaround:
set a shared temp dir with open perms:
export TMPDIR=/tmp/spark-tmp
mkdir -p /tmp/spark-tmp && chmod 1777 /tmp/spark-tmp