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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: [PATCH v5 17/23] powerpc/book3s64/kuap: Improve error reporting with KUAP
Date: Thu, 27 Aug 2020 09:39:25 +0530	[thread overview]
Message-ID: <20200827040931.297759-18-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200827040931.297759-1-aneesh.kumar@linux.ibm.com>

With hash translation use DSISR_KEYFAULT to identify a wrong access.
With Radix we look at the AMR value and type of fault.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/include/asm/book3s/32/kup.h     |  4 +--
 arch/powerpc/include/asm/book3s/64/kup.h     | 27 ++++++++++++++++----
 arch/powerpc/include/asm/kup.h               |  4 +--
 arch/powerpc/include/asm/nohash/32/kup-8xx.h |  4 +--
 arch/powerpc/mm/fault.c                      |  2 +-
 5 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 32fd4452e960..b18cd931e325 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -177,8 +177,8 @@ static inline void restore_user_access(unsigned long flags)
 		allow_user_access(to, to, end - addr, KUAP_READ_WRITE);
 }
 
-static inline bool
-bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
+static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
+				  bool is_write, unsigned long error_code)
 {
 	unsigned long begin = regs->kuap & 0xf0000000;
 	unsigned long end = regs->kuap << 28;
diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index 878cd84922d8..9c85e4397b2d 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -330,12 +330,29 @@ static inline void restore_user_access(unsigned long flags)
 	set_kuap(flags);
 }
 
-static inline bool
-bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
+#define RADIX_KUAP_BLOCK_READ	UL(0x4000000000000000)
+#define RADIX_KUAP_BLOCK_WRITE	UL(0x8000000000000000)
+
+static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
+				  bool is_write, unsigned long error_code)
 {
-	return WARN(mmu_has_feature(MMU_FTR_KUAP) &&
-		    (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)),
-		    "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
+	if (!mmu_has_feature(MMU_FTR_KUAP))
+		return false;
+
+	if (radix_enabled()) {
+		/*
+		 * Will be a storage protection fault.
+		 * Only check the details of AMR[0]
+		 */
+		return WARN((regs->kuap & (is_write ? RADIX_KUAP_BLOCK_WRITE : RADIX_KUAP_BLOCK_READ)),
+			    "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
+	}
+	/*
+	 * We don't want to WARN here because userspace can setup
+	 * keys such that a kernel access to user address can cause
+	 * fault
+	 */
+	return !!(error_code & DSISR_KEYFAULT);
 }
 #endif /* CONFIG_PPC_KUAP */
 
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 6c3ee976ee15..8f5e2d820723 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -67,8 +67,8 @@ static inline void prevent_user_access(void __user *to, const void __user *from,
 				       unsigned long size, unsigned long dir) { }
 static inline unsigned long prevent_user_access_return(void) { return 0UL; }
 static inline void restore_user_access(unsigned long flags) { }
-static inline bool
-bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
+static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
+				  bool is_write, unsigned long error_code)
 {
 	return false;
 }
diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
index 85ed2390fb99..c401e4e404d4 100644
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -60,8 +60,8 @@ static inline void restore_user_access(unsigned long flags)
 	mtspr(SPRN_MD_AP, flags);
 }
 
-static inline bool
-bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
+static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
+				  bool is_write, unsigned long error_code)
 {
 	return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xf0000000),
 		    "Bug: fault blocked by AP register !");
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 0add963a849b..c91621df0c61 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -227,7 +227,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
 
 	// Read/write fault in a valid region (the exception table search passed
 	// above), but blocked by KUAP is bad, it can never succeed.
-	if (bad_kuap_fault(regs, address, is_write))
+	if (bad_kuap_fault(regs, address, is_write, error_code))
 		return true;
 
 	// What's left? Kernel fault on user in well defined regions (extable
-- 
2.26.2


  parent reply	other threads:[~2020-08-27  4:40 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-27  4:09 [PATCH v5 00/23] Kernel userspace access/execution prevention with hash translation Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 01/23] powerpc: Add new macro to handle NESTED_IFCLR Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 02/23] KVM: PPC: BOOK3S: PR: Ignore UAMOR SPR Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 03/23] powerpc/book3s64/kuap/kuep: Make KUAP and KUEP a subfeature of PPC_MEM_KEYS Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 04/23] powerpc/book3s64/kuap/kuep: Move uamor setup to pkey init Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 05/23] powerpc/book3s64/kuap: Move KUAP related function outside radix Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 06/23] powerpc/book3s64/kup: Use the correct #ifdef when including headers Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 07/23] powerpc/book3s64/kuep: Move KUEP related function outside radix Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 08/23] powerpc/book3s64/kuap: Rename MMU_FTR_RADIX_KUAP to MMU_FTR_KUAP Aneesh Kumar K.V
2020-08-27  4:57   ` Christophe Leroy
2020-08-27  4:09 ` [PATCH v5 09/23] powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation Aneesh Kumar K.V
2020-10-18  3:46   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 10/23] powerpc/exec: Set thread.regs early during exec Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 11/23] powerpc/book3s64/pkeys: Store/restore userspace AMR/IAMR correctly on entry and exit from kernel Aneesh Kumar K.V
2020-10-18  3:49   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 12/23] powerpc/book3s64/pkeys: Inherit correctly on fork Aneesh Kumar K.V
2020-10-18  3:50   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 13/23] powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec Aneesh Kumar K.V
2020-10-18  3:50   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 14/23] powerpc/ptrace-view: Use pt_regs values instead of thread_struct based one Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 15/23] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode Aneesh Kumar K.V
2020-10-18  3:52   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 16/23] powerpc/book3s64/kuap: Restrict access to userspace based on userspace AMR Aneesh Kumar K.V
2020-10-18  4:00   ` Sandipan Das
2020-08-27  4:09 ` Aneesh Kumar K.V [this message]
2020-08-27  4:09 ` [PATCH v5 18/23] powerpc/book3s64/kuap: Use Key 3 to implement KUAP with hash translation Aneesh Kumar K.V
2020-10-18  4:00   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 19/23] powerpc/book3s64/kuep: Use Key 3 to implement KUEP " Aneesh Kumar K.V
2020-10-18  4:01   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 20/23] powerpc/book3s64/hash/kuap: Enable kuap on hash Aneesh Kumar K.V
2020-09-12 11:54   ` Michael Ellerman
2020-10-18  4:02   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 21/23] powerpc/book3s64/hash/kuep: Enable KUEP " Aneesh Kumar K.V
2020-10-18  4:03   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 22/23] powerpc/book3s64/hash/kup: Don't hardcode kup key Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 23/23] powerpc/book3s64/pkeys: Optimize FTR_KUAP and FTR_KUEP disabled case Aneesh Kumar K.V

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