cad_pid is global, and kill_cad_pid() is only used in the root namespace.
However, due to pid_table_root_permissions(), a non-root user can unshare
pid/user namespaces and modify it from the child namespace. This makes no
sense and is simply wrong.
Move it to kern_reboot_table[] where it logically belongs; this ensures
that only GLOBAL_ROOT_UID can read/modify this sysctl.
Note that this patch doesn't preserve "#ifdef CONFIG_PROC_SYSCTL" around
the "cad_pid"; CONFIG_PROC_SYSCTL selects CONFIG_SYSCTL, so it is always
set when kern_reboot_table[] is compiled.
Cc: stable@vger.kernel.org
Fixes: e054bcbe7e ("sysctl: move cad_pid into kernel/pid.c")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Alexey Gladkov <legion@kernel.org>
Reviewed-by: Bradley Morgan <include@grrlz.net>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
7170ca0162