Commit c252f384 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/kuap: Check KUAP activation in generic functions 



Today, every platform checks that KUAP is not de-activated
before doing the real job.

Move the verification out of platform specific functions.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/894f110397fcd248e125fb855d1e863e4e633a0d.1634627931.git.christophe.leroy@csgroup.eu
parent ba454f9c

arch/powerpc/include/asm/book3s/32/kup.h

+5 −29
Original line number Diff line number Diff line
@@ -13,11 +13,6 @@ 


extern struct static_key_false disable_kuap_key;



static __always_inline bool kuap_is_disabled(void)

{

	return !IS_ENABLED(CONFIG_PPC_KUAP) || static_branch_unlikely(&disable_kuap_key);

}



static __always_inline bool kuep_is_disabled(void)

{

	return !IS_ENABLED(CONFIG_PPC_KUEP);
@@ -30,6 +25,11 @@ static __always_inline bool kuep_is_disabled(void) 
#define KUAP_NONE	(~0UL)

#define KUAP_ALL	(~1UL)



static __always_inline bool kuap_is_disabled(void)

{

	return static_branch_unlikely(&disable_kuap_key);

}



static inline void kuap_lock_one(unsigned long addr)

{

	mtsr(mfsr(addr) | SR_KS, addr);
@@ -81,9 +81,6 @@ static inline void __kuap_save_and_lock(struct pt_regs *regs) 
{

	unsigned long kuap = current->thread.kuap;



	if (kuap_is_disabled())

		return;



	regs->kuap = kuap;

	if (unlikely(kuap == KUAP_NONE))

		return;
@@ -98,9 +95,6 @@ static inline void kuap_user_restore(struct pt_regs *regs) 


static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)

{

	if (kuap_is_disabled())

		return;



	if (unlikely(kuap != KUAP_NONE)) {

		current->thread.kuap = KUAP_NONE;

		kuap_lock(kuap, false);
@@ -118,9 +112,6 @@ static inline unsigned long __kuap_get_and_assert_locked(void) 
{

	unsigned long kuap = current->thread.kuap;



	if (kuap_is_disabled())

		return KUAP_NONE;



	WARN_ON_ONCE(IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && kuap != KUAP_NONE);



	return kuap;
@@ -134,9 +125,6 @@ static inline void __kuap_assert_locked(void) 
static __always_inline void __allow_user_access(void __user *to, const void __user *from,

						u32 size, unsigned long dir)

{

	if (kuap_is_disabled())

		return;



	BUILD_BUG_ON(!__builtin_constant_p(dir));



	if (!(dir & KUAP_WRITE))
@@ -150,9 +138,6 @@ static __always_inline void __prevent_user_access(unsigned long dir) 
{

	u32 kuap = current->thread.kuap;



	if (kuap_is_disabled())

		return;



	BUILD_BUG_ON(!__builtin_constant_p(dir));



	if (!(dir & KUAP_WRITE))
@@ -166,9 +151,6 @@ static inline unsigned long __prevent_user_access_return(void) 
{

	unsigned long flags = current->thread.kuap;



	if (kuap_is_disabled())

		return KUAP_NONE;



	if (flags != KUAP_NONE) {

		current->thread.kuap = KUAP_NONE;

		kuap_lock(flags, true);
@@ -179,9 +161,6 @@ static inline unsigned long __prevent_user_access_return(void) 


static inline void __restore_user_access(unsigned long flags)

{

	if (kuap_is_disabled())

		return;



	if (flags != KUAP_NONE) {

		current->thread.kuap = flags;

		kuap_unlock(flags, true);
@@ -193,9 +172,6 @@ __bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) 
{

	unsigned long kuap = regs->kuap;



	if (kuap_is_disabled())

		return false;



	if (!is_write || kuap == KUAP_ALL)

		return false;

	if (kuap == KUAP_NONE)

arch/powerpc/include/asm/book3s/64/kup.h

+20 −21
Original line number Diff line number Diff line
@@ -229,6 +229,11 @@ static inline u64 current_thread_iamr(void) 


#ifdef CONFIG_PPC_KUAP



static __always_inline bool kuap_is_disabled(void)

{

	return !mmu_has_feature(MMU_FTR_BOOK3S_KUAP);

}



static inline void kuap_user_restore(struct pt_regs *regs)

{

	bool restore_amr = false, restore_iamr = false;
@@ -270,36 +275,32 @@ static inline void kuap_user_restore(struct pt_regs *regs) 


static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)

{

	if (mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) {

		if (unlikely(regs->amr != amr)) {

	if (likely(regs->amr == amr))

		return;



	isync();

	mtspr(SPRN_AMR, regs->amr);

	/*

	 * No isync required here because we are about to rfi

	 * back to previous context before any user accesses

	 * would be made, which is a CSI.

			 */

		}

	}

	/*

	 *

	 * No need to restore IAMR when returning to kernel space.

	 */

}



static inline unsigned long __kuap_get_and_assert_locked(void)

{

	if (mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) {

	unsigned long amr = mfspr(SPRN_AMR);



	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG)) /* kuap_check_amr() */

		WARN_ON_ONCE(amr != AMR_KUAP_BLOCKED);

	return amr;

}

	return 0;

}



static inline void __kuap_assert_locked(void)

{

	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && mmu_has_feature(MMU_FTR_BOOK3S_KUAP))

	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))

		WARN_ON_ONCE(mfspr(SPRN_AMR) != AMR_KUAP_BLOCKED);

}
@@ -340,8 +341,6 @@ static inline void set_kuap(unsigned long value) 


static inline bool __bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)

{

	if (!mmu_has_feature(MMU_FTR_BOOK3S_KUAP))

		return false;

	/*

	 * For radix this will be a storage protection fault (DSISR_PROTFAULT).

	 * For hash this will be a key fault (DSISR_KEYFAULT)

arch/powerpc/include/asm/kup.h

+29 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ void setup_kuap(bool disabled); 
#else

static inline void setup_kuap(bool disabled) { }



static __always_inline bool kuap_is_disabled(void) { return true; }



static inline bool

__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)

{
@@ -73,28 +75,43 @@ static inline void __restore_user_access(unsigned long flags) { } 
static __always_inline bool

bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)

{

	if (kuap_is_disabled())

		return false;



	return __bad_kuap_fault(regs, address, is_write);

}



static __always_inline void kuap_assert_locked(void)

{

	if (kuap_is_disabled())

		return;



	__kuap_assert_locked();

}



#ifdef CONFIG_PPC32

static __always_inline void kuap_save_and_lock(struct pt_regs *regs)

{

	if (kuap_is_disabled())

		return;



	__kuap_save_and_lock(regs);

}

#endif



static __always_inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)

{

	if (kuap_is_disabled())

		return;



	__kuap_kernel_restore(regs, amr);

}



static __always_inline unsigned long kuap_get_and_assert_locked(void)

{

	if (kuap_is_disabled())

		return 0;



	return __kuap_get_and_assert_locked();

}
@@ -102,21 +119,33 @@ static __always_inline unsigned long kuap_get_and_assert_locked(void) 
static __always_inline void allow_user_access(void __user *to, const void __user *from,

				     unsigned long size, unsigned long dir)

{

	if (kuap_is_disabled())

		return;



	__allow_user_access(to, from, size, dir);

}



static __always_inline void prevent_user_access(unsigned long dir)

{

	if (kuap_is_disabled())

		return;



	__prevent_user_access(dir);

}



static __always_inline unsigned long prevent_user_access_return(void)

{

	if (kuap_is_disabled())

		return 0;



	return __prevent_user_access_return();

}



static __always_inline void restore_user_access(unsigned long flags)

{

	if (kuap_is_disabled())

		return;



	__restore_user_access(flags);

}

#endif /* CONFIG_PPC_BOOK3S_64 */

arch/powerpc/include/asm/nohash/32/kup-8xx.h

+2 −26
Original line number Diff line number Diff line
@@ -22,9 +22,6 @@ static __always_inline bool kuap_is_disabled(void) 


static inline void __kuap_save_and_lock(struct pt_regs *regs)

{

	if (kuap_is_disabled())

		return;



	regs->kuap = mfspr(SPRN_MD_AP);

	mtspr(SPRN_MD_AP, MD_APG_KUAP);

}
@@ -35,9 +32,6 @@ static inline void kuap_user_restore(struct pt_regs *regs) 


static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)

{

	if (kuap_is_disabled())

		return;



	mtspr(SPRN_MD_AP, regs->kuap);

}
@@ -45,9 +39,6 @@ static inline unsigned long __kuap_get_and_assert_locked(void) 
{

	unsigned long kuap;



	if (kuap_is_disabled())

		return MD_APG_INIT;



	kuap = mfspr(SPRN_MD_AP);



	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
@@ -58,24 +49,18 @@ static inline unsigned long __kuap_get_and_assert_locked(void) 


static inline void __kuap_assert_locked(void)

{

	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && !kuap_is_disabled())

		kuap_get_and_assert_locked();

	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))

		__kuap_get_and_assert_locked();

}



static inline void __allow_user_access(void __user *to, const void __user *from,

				       unsigned long size, unsigned long dir)

{

	if (kuap_is_disabled())

		return;



	mtspr(SPRN_MD_AP, MD_APG_INIT);

}



static inline void __prevent_user_access(unsigned long dir)

{

	if (kuap_is_disabled())

		return;



	mtspr(SPRN_MD_AP, MD_APG_KUAP);

}
@@ -83,9 +68,6 @@ static inline unsigned long __prevent_user_access_return(void) 
{

	unsigned long flags;



	if (kuap_is_disabled())

		return MD_APG_INIT;



	flags = mfspr(SPRN_MD_AP);



	mtspr(SPRN_MD_AP, MD_APG_KUAP);
@@ -95,18 +77,12 @@ static inline unsigned long __prevent_user_access_return(void) 


static inline void __restore_user_access(unsigned long flags)

{

	if (kuap_is_disabled())

		return;



	mtspr(SPRN_MD_AP, flags);

}



static inline bool

__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)

{

	if (kuap_is_disabled())

		return false;



	return !((regs->kuap ^ MD_APG_KUAP) & 0xff000000);

}