powerpc: Add skeleton for Kernel Userspace Execution Prevention

This patch adds a skeleton for Kernel Userspace Execution Prevention.

Then subarches implementing it have to define CONFIG_PPC_HAVE_KUEP
and provide setup_kuep() function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Don't split strings, use pr_crit_ratelimited()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 4 insertions, 5 deletions

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 887f11bcf330..3384354abc1d 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -229,11 +229,10 @@ static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
         /* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
         if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
                                       DSISR_PROTFAULT))) {
-                printk_ratelimited(KERN_CRIT "kernel tried to execute"
-                                   " exec-protected page (%lx) -"
-                                   "exploit attempt? (uid: %d)\n",
-                                   address, from_kuid(&init_user_ns,
-                                                      current_uid()));
+                pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n",
+                                    address >= TASK_SIZE ? "exec-protected" : "user",
+                                    address,
+                                    from_kuid(&init_user_ns, current_uid()));
         }
         return is_exec || (address >= TASK_SIZE);
 }