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Message-Id: <20bdff208e64d1c6830c47e0e8a5506f07ce8fa7.1633707305.git.christophe.leroy@csgroup.eu>
Date: Fri, 8 Oct 2021 17:40:32 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 04/16] 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: Christophe Leroy <christophe.leroy@...roup.eu>
---
v2: Added missing check in bad_kuap_fault()
---
arch/powerpc/include/asm/book3s/32/kup.h | 34 +++-------------
arch/powerpc/include/asm/book3s/64/kup.h | 41 ++++++++++----------
arch/powerpc/include/asm/kup.h | 29 ++++++++++++++
arch/powerpc/include/asm/nohash/32/kup-8xx.h | 28 +------------
4 files changed, 56 insertions(+), 76 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 8f04602dffff..f1617ba85068 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -16,11 +16,6 @@ extern struct static_key_false disable_kuep_key;
extern s32 patch__kuep_lock, patch__kuep_unlock;
-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) || static_branch_unlikely(&disable_kuep_key);
@@ -33,6 +28,11 @@ 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);
@@ -84,9 +84,6 @@ 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;
@@ -101,9 +98,6 @@ 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);
@@ -121,9 +115,6 @@ 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;
@@ -137,9 +128,6 @@ 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))
@@ -153,9 +141,6 @@ 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))
@@ -169,9 +154,6 @@ 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);
@@ -182,9 +164,6 @@ 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);
@@ -196,9 +175,6 @@ __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)
diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index 03d61c5205a4..9f2099790658 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -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)) {
- 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.
- */
- }
- }
+ 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;
+ 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;
}
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)
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 3dbd3f77b413..ea70e6f1df1e 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -43,6 +43,8 @@ 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)
{
@@ -76,28 +78,43 @@ 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();
}
@@ -105,21 +122,33 @@ 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 */
diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
index a5db84164afd..74f15c386476 100644
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -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);
}
--
2.31.1
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