Linux 6.16 Merge Window

29 May 2025 tags: audit lsm selinux

Linux v6.15 was released on Sunday, May 25th, with the Linux v6.16 merge window opening immediately afterwards. Below are the highlights of the LSM, SELinux, and audit pull requests which have been merged into Linus’ tree.

LSM

• Move the security_netlink_send() LSM hook under the Kconfig CONFIG_SECURITY_NETWORK tunable.

SELinux

• Reduce the SELinux impact on path walks through the addition of a small directory access cache to the per-task SELinux state. This cache allows SELinux to cache the most recently used directory access decisions in order to avoid repeatedly querying the Access Vector Cache (AVC) on path walks where the majority of the directories have similar security contexts/labels. Crude performance measurements taken prior to this patch indicated that time spent in the SELinux code on a make allmodconfig run was 103% that of __d_lookup_rcu(), and with this patch the time spent in the SELinux code dropped to 63% of __d_lookup_rcu(), a ~40% improvement.

• Add support for wildcards in genfscon policy statements as opposed to the current prefix matching approach. Adding wilcard support allows for more expressive and efficient path matching in the policy which is especially helpful for filesystems such as sysfs. Early work has shown a ~15% boot time reduction on Android. SELinux policies can opt into wilcard matching by enabling the genfs_seclabel_wildcard policy capability.

• Unify the out of memory error handling of the SELinux network and InfiniBand object caches to ensure that cache allocation failures still return the object label and do not fail the operation. While the object label may not be cached in this case, future object lookups will continue to attempt to cache the object’s label.

• Minor improvements around constification, ‘likely’ annotations, and removal of bogus code comments.

Audit

• Always record AUDIT_ANOM events when auditing is enabled. Prior to this change AUDIT_ANOM events were only recorded if auditing was enabled and the admin/distro had explicitly configured audit beyond the defaults.

• Annotate the audit_log_vformat() function with the __printf() attribute to quiet warnings on modern GCC compilers.