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>
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 887f11b..3384354 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);
}
diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
index 36d28e8..83f95a5 100644
--- a/arch/powerpc/mm/init-common.c
+++ b/arch/powerpc/mm/init-common.c
@@ -26,8 +26,19 @@
#include <asm/pgtable.h>
#include <asm/kup.h>
+static bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
+
+static int __init parse_nosmep(char *p)
+{
+ disable_kuep = true;
+ pr_warn("Disabling Kernel Userspace Execution Prevention\n");
+ return 0;
+}
+early_param("nosmep", parse_nosmep);
+
void __init setup_kup(void)
{
+ setup_kuep(disable_kuep);
}
#define CTOR(shift) static void ctor_##shift(void *addr) \
