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1e6854e112
Change the default udev rule for /dev/ptp* from 0660 to 0664,
allowing unprivileged users read-only access.
NIC telemetry and hardware logs often use device timestamps that must
be correlated with host time via read-only PTP ioctls (e.g.
cross-timestamp queries). Requiring privileged access makes these
workflows unnecessarily restrictive.
Older kernels lacked proper permission checks in some PTP ioctls.
Kernel commit b4e53b15c04e3852949003752f48f7a14ae39e86 ("ptp: Add PHC
file mode checks. Allow RO adjtime() without FMODE_WRITE.") introduces
the necessary file mode validation, ensuring that read access does not
permit clock modification or configuration changes, which still require
write permissions.
This commit has been backported to all actively maintained stable
kernel branches.
Related to #31034
Files in this directory contain configuration for systemd-udevd.service, a daemon that manages symlinks to device nodes, permissions of devices nodes, emits device events for userspace, and renames network interfaces. See man:udev(7) for an overview of the configuration file format, and man:systemd-udevd.service(8) for a description of service itself. Use 'systemd-analyze cat-config udev/rules.d' to display the effective config.