Commit 0fb1c25a authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

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: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
[mpe: Don't split strings, use pr_crit_ratelimited()]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 69795cab

Documentation/admin-guide/kernel-parameters.txt

+1 −1
Original line number Diff line number Diff line
@@ -2843,7 +2843,7 @@ 
			Disable SMAP (Supervisor Mode Access Prevention)

			even if it is supported by processor.



	nosmep		[X86]

	nosmep		[X86,PPC]

			Disable SMEP (Supervisor Mode Execution Prevention)

			even if it is supported by processor.

arch/powerpc/include/asm/kup.h

+6 −0
Original line number Diff line number Diff line
@@ -6,6 +6,12 @@ 


void setup_kup(void);



#ifdef CONFIG_PPC_KUEP

void setup_kuep(bool disabled);

#else

static inline void setup_kuep(bool disabled) { }

#endif /* CONFIG_PPC_KUEP */



#endif /* !__ASSEMBLY__ */



#endif /* _ASM_POWERPC_KUP_H_ */

arch/powerpc/mm/fault.c

+4 −5
Original line number Diff line number Diff line
@@ -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);

}

arch/powerpc/mm/init-common.c

+11 −0
Original line number Diff line number Diff line
@@ -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) \

arch/powerpc/platforms/Kconfig.cputype

+12 −0
Original line number Diff line number Diff line
@@ -345,6 +345,18 @@ config PPC_RADIX_MMU_DEFAULT 


	  If you're unsure, say Y.



config PPC_HAVE_KUEP

	bool



config PPC_KUEP

	bool "Kernel Userspace Execution Prevention"

	depends on PPC_HAVE_KUEP

	default y

	help

	  Enable support for Kernel Userspace Execution Prevention (KUEP)



	  If you're unsure, say Y.



config ARCH_ENABLE_HUGEPAGE_MIGRATION

	def_bool y

	depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION

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