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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>,
	linuxram@us.ibm.com, bauerman@linux.ibm.com
Subject: [PATCH v4 31/41] powerpc/book3s64/kuap: Improve error reporting with KUAP
Date: Mon, 15 Jun 2020 11:44:20 +0530	[thread overview]
Message-ID: <20200615061430.770174-32-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200615061430.770174-1-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     | 28 ++++++++++++++++----
 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, 30 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 fcb1d5eb54dc..0fcdd63d0de8 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -340,14 +340,32 @@ 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 */
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_BOOK3S_64_KUP_H */
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 015f51b02741..a29f69bbf6ec 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -59,8 +59,8 @@ 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 2393ed9d84bb..785c3e32c4e7 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -260,7 +260,7 @@ 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:[~2020-06-15  7:18 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-15  6:13 [PATCH v4 00/41] Kernel userspace access/execution prevention with hash translation Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 01/41] powerpc/book3s64/pkeys: Fixup bit numbering Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 02/41] powerpc/book3s64/pkeys: pkeys are supported only on hash on book3s Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 03/41] powerpc/book3s64/pkeys: Move pkey related bits in the linux page table Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 04/41] powerpc/book3s64/pkeys: Explain key 1 reservation details Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 05/41] powerpc/book3s64/pkeys: Simplify the key initialization Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 06/41] powerpc/book3s64/pkeys: Prevent key 1 modification from userspace Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 07/41] powerpc/book3s64/pkeys: kill cpu feature key CPU_FTR_PKEY Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 08/41] powerpc/book3s64/pkeys: Convert execute key support to static key Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 09/41] powerpc/book3s64/pkeys: Simplify pkey disable branch Aneesh Kumar K.V
2020-06-15  6:13 ` [PATCH v4 10/41] powerpc/book3s64/pkeys: Convert pkey_total to max_pkey Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 11/41] powerpc/book3s64/pkeys: Make initial_allocation_mask static Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 12/41] powerpc/book3s64/pkeys: Mark all the pkeys above max pkey as reserved Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 13/41] powerpc/book3s64/pkeys: Enable MMU_FTR_PKEY Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 14/41] powerpc/book3s64/kuep: Add MMU_FTR_KUEP Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 15/41] powerpc/book3s64/pkeys: Use execute_pkey_disable static key Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 16/41] powerpc/book3s64/pkeys: Use MMU_FTR_PKEY instead of pkey_disabled " Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 17/41] powerpc/book3s64/kuap: Move KUAP related function outside radix Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 18/41] powerpc/book3s64/kuep: Move KUEP " Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 19/41] powerpc/book3s64/kuap: Rename MMU_FTR_RADIX_KUAP to MMU_FTR_KUAP Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 20/41] powerpc/book3s64/kuap/kuep: Make KUAP and KUEP a subfeature of PPC_MEM_KEYS Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 21/41] powerpc/book3s64/kuap: Move UAMOR setup to key init function Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 22/41] powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 23/41] powerpc/exec: Set thread.regs early during exec Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 24/41] powerpc/book3s64/pkeys: Store/restore userspace AMR correctly on entry and exit from kernel Aneesh Kumar K.V
2020-07-03  9:18   ` Nicholas Piggin
2020-07-03  9:30     ` Aneesh Kumar K.V
2020-07-07  6:23       ` Nicholas Piggin
2020-06-15  6:14 ` [PATCH v4 25/41] powerpc/book3s64/kuep: Store/restore userspace IAMR " Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 26/41] powerpc/book3s64/pkeys: Inherit correctly on fork Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 27/41] powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 28/41] powerpc/ptrace-view: Use pt_regs values instead of thread_struct based one Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 29/41] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 30/41] powerpc/book3s64/kuap: Restrict access to userspace based on userspace AMR Aneesh Kumar K.V
2020-06-15  6:14 ` Aneesh Kumar K.V [this message]
2020-06-15  6:14 ` [PATCH v4 32/41] powerpc/book3s64/kuap: Use Key 3 to implement KUAP with hash translation Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 33/41] powerpc/book3s64/kuep: Use Key 3 to implement KUEP " Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 34/41] powerpc/book3s64/hash/kuap: Enable kuap on hash Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 35/41] powerpc/book3s64/hash/kuep: Enable KUEP " Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 36/41] powerpc/book3s64/keys: Print information during boot Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 37/41] powerpc/selftest/ptrave-pkey: Rename variables to make it easier to follow code Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 38/41] powerpc/selftest/ptrace-pkey: Update the test to mark an invalid pkey correctly Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 39/41] powerpc/selftest/ptrace-pkey: IAMR and uamor cannot be updated by ptrace Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 40/41] powerpc/book3s64/keys/kuap: Reset AMR/IAMR values on kexec Aneesh Kumar K.V
2020-06-15  6:14 ` [PATCH v4 41/41] powerpc/book3s64/hash/kup: Don't hardcode kup key Aneesh Kumar K.V

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