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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org
Cc: akpm@linux-foundation.org, dave.hansen@intel.com,
	sean.j.christopherson@intel.com, nhorman@redhat.com,
	npmccallum@redhat.com, serge.ayoun@intel.com,
	shay.katz-zamir@intel.com, haitao.huang@intel.com,
	andriy.shevchenko@linux.intel.com, tglx@linutronix.de,
	kai.svahn@intel.com, bp@alien8.de, josh@joshtriplett.org,
	luto@kernel.org, kai.huang@intel.com, rientjes@google.com,
	cedric.xing@intel.com
Subject: [PATCH v22 17/24] x86/fault: Add helper function to sanitize error code
Date: Tue,  3 Sep 2019 17:26:48 +0300
Message-ID: <20190903142655.21943-18-jarkko.sakkinen@linux.intel.com> (raw)
In-Reply-To: <20190903142655.21943-1-jarkko.sakkinen@linux.intel.com>

From: Sean Christopherson <sean.j.christopherson@intel.com>

...to prepare for vDSO exception fixup, which will expose the error code
to userspace and runs before set_signal_archinfo(), i.e. suppresses the
signal when fixup is successful.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/mm/fault.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index c2dea3f9e263..7efaf0269951 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -681,6 +681,18 @@ pgtable_bad(struct pt_regs *regs, unsigned long error_code,
 	oops_end(flags, regs, sig);
 }
 
+static void sanitize_error_code(unsigned long address,
+				unsigned long *error_code)
+{
+	/*
+	 * To avoid leaking information about the kernel page
+	 * table layout, pretend that user-mode accesses to
+	 * kernel addresses are always protection faults.
+	 */
+	if (address >= TASK_SIZE_MAX)
+		*error_code |= X86_PF_PROT;
+}
+
 static void set_signal_archinfo(unsigned long address,
 				unsigned long error_code)
 {
@@ -737,6 +749,8 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 		 * faulting through the emulate_vsyscall() logic.
 		 */
 		if (current->thread.sig_on_uaccess_err && signal) {
+			sanitize_error_code(address, &error_code);
+
 			set_signal_archinfo(address, error_code);
 
 			/* XXX: hwpoison faults will set the wrong code. */
@@ -885,13 +899,7 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
 		if (is_errata100(regs, address))
 			return;
 
-		/*
-		 * To avoid leaking information about the kernel page table
-		 * layout, pretend that user-mode accesses to kernel addresses
-		 * are always protection faults.
-		 */
-		if (address >= TASK_SIZE_MAX)
-			error_code |= X86_PF_PROT;
+		sanitize_error_code(address, &error_code);
 
 		if (likely(show_unhandled_signals))
 			show_signal_msg(regs, error_code, address, tsk);
@@ -1008,6 +1016,8 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
 	if (is_prefetch(regs, error_code, address))
 		return;
 
+	sanitize_error_code(address, &error_code);
+
 	set_signal_archinfo(address, error_code);
 
 #ifdef CONFIG_MEMORY_FAILURE
-- 
2.20.1


  parent reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-03 14:26 [PATCH v22 00/24] Intel SGX foundations Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 02/24] x86/cpufeatures: x86/msr: Intel SGX Launch Control " Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 04/24] x86/cpu/intel: Detect SGX supprt Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 05/24] x86/sgx: Add ENCLS architectural error codes Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 06/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 07/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 08/24] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 09/24] x86/sgx: Add functions to allocate and free EPC pages Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 10/24] x86/sgx: Add sgx_einit() for wrapping ENCLS[EINIT] Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 11/24] mm: Introduce vm_ops->may_mprotect() Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 12/24] x86/sgx: Linux Enclave Driver Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 13/24] x86/sgx: Add provisioning Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 14/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 15/24] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 16/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2019-09-03 14:26 ` Jarkko Sakkinen [this message]
2019-09-03 14:26 ` [PATCH v22 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 19/24] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 20/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 21/24] selftests/x86: Recurse into subdirectories Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 22/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 23/24] docs: x86/sgx: Document microarchitecture Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 24/24] docs: x86/sgx: Document kernel internals Jarkko Sakkinen
2019-09-13 20:38 ` [PATCH v22 00/24] Intel SGX foundations Dave Hansen
2019-09-14 13:41   ` Jarkko Sakkinen
2019-09-14 15:32     ` Dave Hansen
2019-09-16  5:23       ` Jarkko Sakkinen

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