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, npiggin@gmail.com
Subject: [PATCH v2 19/28] powerpc/book3s64/kuap: Improve error reporting with KUAP
Date: Sat, 2 May 2020 16:52:20 +0530 [thread overview]
Message-ID: <20200502112229.545331-20-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200502112229.545331-1-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 3c0ba22dc360..213d3ab40d2d 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -176,8 +176,8 @@ 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 f097d69ec2c8..66c97d9d2ed8 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -317,13 +317,31 @@ 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);
}
+
#else /* CONFIG_PPC_MEM_KEYS */
static inline void kuap_restore_user_amr(struct pt_regs *regs)
{
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 248438dff74a..249eed77a06b 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -57,8 +57,8 @@ 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 84af6c8eecf7..4e6e7e0fea21 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -233,7 +233,7 @@ 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
next prev parent reply other threads:[~2020-05-02 12:39 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-02 11:22 [PATCH v2 00/28] Kernel userspace access/execution prevention with hash translation Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 01/28] powerpc/book3s64/pkeys: Enable MMU_FTR_PKEY Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 02/28] powerpc/book3s64/kuep: Add MMU_FTR_KUEP Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 03/28] powerpc/book3s64/pkeys: Use execute_pkey_disable static key Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 04/28] powerpc/book3s64/pkeys: Use MMU_FTR_PKEY instead of pkey_disabled " Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 05/28] powerpc/book3s64/kuap: Move KUAP related function outside radix Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 06/28] powerpc/book3s64/kuep: Move KUEP " Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 07/28] powerpc/book3s64/kuap: Rename MMU_FTR_RADIX_KUAP to MMU_FTR_KUAP Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 08/28] powerpc/book3s64/kuap/kuep: Make KUAP and KUEP a subfeature of PPC_MEM_KEYS Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 09/28] powerpc/book3s64/kuap: Move UAMOR setup to key init function Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 10/28] powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 11/28] powerpc/exec: Set thread.regs early during exec Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 12/28] powerpc/book3s64/pkeys: Store/restore userspace AMR correctly on entry and exit from kernel Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 13/28] powerpc/book3s64/kuep: Store/restore userspace IAMR " Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 14/28] powerpc/book3s64/pkeys: Inherit correctly on fork Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 15/28] powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec Aneesh Kumar K.V
2020-05-07 14:25 ` Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 16/28] powerpc/ptrace-view: Use pt_regs values instead of thread_struct based one Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 17/28] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 18/28] powerpc/book3s64/kuap: Restrict access to userspace based on userspace AMR Aneesh Kumar K.V
2020-05-02 11:22 ` Aneesh Kumar K.V [this message]
2020-05-02 11:22 ` [PATCH v2 20/28] powerpc/book3s64/kuap: Use Key 3 to implement KUAP with hash translation Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 21/28] powerpc/book3s64/kuep: Use Key 3 to implement KUEP " Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 22/28] powerpc/book3s64/hash/kuap: Enable kuap on hash Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 23/28] powerpc/book3s64/hash/kuep: Enable KUEP " Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 24/28] powerpc/book3s64/keys: Print information during boot Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 25/28] powerpc/selftest/ptrave-pkey: Rename variables to make it easier to follow code Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 26/28] powerpc/selftest/ptrace-pkey: Update the test to mark an invalid pkey correctly Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 27/28] powerpc/selftest/ptrace-pkey: IAMR and uamor cannot be updated by ptrace Aneesh Kumar K.V
2020-05-02 11:22 ` [PATCH v2 28/28] powerpc/book3s64/keys/kuap: Reset AMR/IAMR values on kexec Aneesh Kumar K.V
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