Introduced to the Linux kernel nearly six years ago was [1]the Syscall User Dispatch feature to help with Linux gaming . Specifically, Syscall User Dispatch was developed to [2]help Windows games run on Linux more efficiently. While it was [3]upstreamed in Linux 5.11 for more efficiently intercepting system calls from Windows software under Wine, now in the name of security there are patches working their way to the mainline kernel to more easily disable it.

In the name of better security, patches are pending that will likely be mainlined for Linux 7.3 to allow disabling [4]Syscall User Dispatch either at kernel build time or run-time via sysctl.

[5]This patch adds CONFIG_SYSCALL_USER_DISPATCH if wanting to disable Syscall User Dispatch at build time. Up to now it lacked a Kconfig knob but was simply enabled with the generic system call support.

There is [6]a second patch adding the kernel.syscall_user_dispatch to disable Syscall User Dispatch support at run-time.

Syscall User Dispatch is remaining enabled by default but with these methods you can optionally restrict its usage if wanting to further lockdown your system. These patches have been queued into tip/tip.git's core/entry Git branch. With the patches now in a TIP branch they are expected to be submitted for the Linux 7.3 merge window in late August.



[1] https://www.phoronix.com/news/Linux-Syscall-User-Dispatch

[2] https://www.phoronix.com/news/Syscall-User-Dispatch-Queued

[3] https://www.phoronix.com/news/Linux-5.11-Core-Entry

[4] https://www.phoronix.com/search/Syscall+User+Dispatch

[5] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=core/entry&id=ee935e8dc757614006ac29a7d98a15882cdcaeb2

[6] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=core/entry&id=5b6e32ba7b5967a2787fafaa9f4740c590e1e00b