syscall_user_dispatch: Add kernel.syscall_user_dispatch sysctl

Add a matching sysctl to go with CONFIG_SYSCALL_USER_DISPATCH.

kernel.syscall_user_dispatch (default 1 - allow) controls whether
userspace may arm syscall user dispatch (both via prctl and ptrace).

Disarming is always permitted - same semantics as comparable knobs.

Disabling while a task has armed syscall user dispatch does not
cause it to become inactive - instead it remains active until the
user attempts to disable/re-enable via prctl or ptrace.  On the
next attempt to re-enable, the prctl/ptrace call fails gracefully.

The alternative would cause programs translating non-linux syscalls
to interpret those syscalls as linux syscalls, resulting in undefined
userland behavior.

Signed-off-by: Gregory Price <gourry@gourry.net>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260706140020.873735-3-gourry@gourry.net

0 files changed, 0 insertions, 0 deletions