Commit 61130e20 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Michael Ellerman
Browse files

powerpc/book3s64/kup: Check max key supported before enabling kup 



Don't enable KUEP/KUAP if we support less than or equal to 3 keys.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201202043854.76406-1-aneesh.kumar@linux.ibm.com
parent c91435d9

arch/powerpc/include/asm/kup.h

+3 −0
Original line number Diff line number Diff line
@@ -44,6 +44,9 @@ 


#else /* !__ASSEMBLY__ */



extern bool disable_kuep;

extern bool disable_kuap;



#include <linux/pgtable.h>



void setup_kup(void);

arch/powerpc/mm/book3s64/pkeys.c

+21 −12
Original line number Diff line number Diff line
@@ -185,6 +185,27 @@ void __init pkey_early_init_devtree(void) 
		default_uamor &= ~(0x3ul << pkeyshift(execute_only_key));

	}



	if (unlikely(num_pkey <= 3)) {

		/*

		 * Insufficient number of keys to support

		 * KUAP/KUEP feature.

		 */

		disable_kuep = true;

		disable_kuap = true;

		WARN(1, "Disabling kernel user protection due to low (%d) max supported keys\n", num_pkey);

	} else {

		/*  handle key which is used by kernel for KAUP */

		reserved_allocation_mask |= (0x1 << 3);

		/*

		 * Mark access for kup_key in default amr so that

		 * we continue to operate with that AMR in

		 * copy_to/from_user().

		 */

		default_amr   &= ~(0x3ul << pkeyshift(3));

		default_iamr  &= ~(0x1ul << pkeyshift(3));

		default_uamor &= ~(0x3ul << pkeyshift(3));

	}



	/*

	 * Allow access for only key 0. And prevent any other modification.

	 */
@@ -205,18 +226,6 @@ void __init pkey_early_init_devtree(void) 
	reserved_allocation_mask |= (0x1 << 1);

	default_uamor &= ~(0x3ul << pkeyshift(1));



	/*  handle key which is used by kernel for KAUP */

	reserved_allocation_mask |= (0x1 << 3);

	/*

	 * Mark access for KUAP key in default amr so that

	 * we continue to operate with that AMR in

	 * copy_to/from_user().

	 */

	default_amr   &= ~(0x3ul << pkeyshift(3));

	default_iamr  &= ~(0x1ul << pkeyshift(3));

	default_uamor &= ~(0x3ul << pkeyshift(3));





	/*

	 * Prevent the usage of OS reserved keys. Update UAMOR

	 * for those keys. Also mark the rest of the bits in the

arch/powerpc/mm/init-common.c

+2 −2
Original line number Diff line number Diff line
@@ -28,8 +28,8 @@ EXPORT_SYMBOL_GPL(kernstart_addr); 
unsigned long kernstart_virt_addr __ro_after_init = KERNELBASE;

EXPORT_SYMBOL_GPL(kernstart_virt_addr);



static bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);

static bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);

bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);

bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);



static int __init parse_nosmep(char *p)

{