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Message-Id: <20200828131606.7946-3-boyan.karatotev@arm.com>
Date: Fri, 28 Aug 2020 14:16:04 +0100
From: Boyan Karatotev <boyan.karatotev@....com>
To: linux-arm-kernel@...ts.infradead.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: vincenzo.frascino@....com, amit.kachhap@....com,
boian4o1@...il.com, Boyan Karatotev <boyan.karatotev@....com>,
Shuah Khan <shuah@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>
Subject: [PATCH 2/4] kselftests/arm64: add nop checks for PAuth tests
PAuth adds sign/verify controls to enable and disable groups of
instructions in hardware for compatibility with libraries that do not
implement PAuth. The kernel always enables them if it detects PAuth.
Add a test that checks that each group of instructions is enabled, if the
kernel reports PAuth as detected.
Note: For groups, for the purpose of this patch, we intend instructions
that use a certain key.
Cc: Shuah Khan <shuah@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Signed-off-by: Boyan Karatotev <boyan.karatotev@....com>
---
.../testing/selftests/arm64/pauth/.gitignore | 1 +
tools/testing/selftests/arm64/pauth/Makefile | 7 ++-
tools/testing/selftests/arm64/pauth/helper.c | 41 +++++++++++++++
tools/testing/selftests/arm64/pauth/helper.h | 10 ++++
tools/testing/selftests/arm64/pauth/pac.c | 51 +++++++++++++++++++
5 files changed, 108 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/arm64/pauth/helper.c
diff --git a/tools/testing/selftests/arm64/pauth/.gitignore b/tools/testing/selftests/arm64/pauth/.gitignore
index b557c916720a..155137d92722 100644
--- a/tools/testing/selftests/arm64/pauth/.gitignore
+++ b/tools/testing/selftests/arm64/pauth/.gitignore
@@ -1 +1,2 @@
+exec_target
pac
diff --git a/tools/testing/selftests/arm64/pauth/Makefile b/tools/testing/selftests/arm64/pauth/Makefile
index 785c775e5e41..a017d1c8dd58 100644
--- a/tools/testing/selftests/arm64/pauth/Makefile
+++ b/tools/testing/selftests/arm64/pauth/Makefile
@@ -4,7 +4,7 @@
CFLAGS += -mbranch-protection=pac-ret
TEST_GEN_PROGS := pac
-TEST_GEN_FILES := pac_corruptor.o
+TEST_GEN_FILES := pac_corruptor.o helper.o
include ../../lib.mk
@@ -13,10 +13,13 @@ include ../../lib.mk
$(OUTPUT)/pac_corruptor.o: pac_corruptor.S
$(CC) -c $^ -o $@ $(CFLAGS) -march=armv8.3-a
+$(OUTPUT)/helper.o: helper.c
+ $(CC) -c $^ -o $@ $(CFLAGS) -march=armv8.3-a
+
# when -mbranch-protection is enabled and the target architecture is ARMv8.3 or
# greater, gcc emits pac* instructions which are not in HINT NOP space,
# preventing the tests from occurring at all. Compile for ARMv8.2 so tests can
# run on earlier targets and print a meaningful error messages
-$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o
+$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o $(OUTPUT)/helper.o
$(CC) $^ -o $@ $(CFLAGS) -march=armv8.2-a
diff --git a/tools/testing/selftests/arm64/pauth/helper.c b/tools/testing/selftests/arm64/pauth/helper.c
new file mode 100644
index 000000000000..8619afb16124
--- /dev/null
+++ b/tools/testing/selftests/arm64/pauth/helper.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 ARM Limited
+
+#include "helper.h"
+
+
+size_t keyia_sign(size_t ptr)
+{
+ asm volatile("paciza %0" : "+r" (ptr));
+ return ptr;
+}
+
+size_t keyib_sign(size_t ptr)
+{
+ asm volatile("pacizb %0" : "+r" (ptr));
+ return ptr;
+}
+
+size_t keyda_sign(size_t ptr)
+{
+ asm volatile("pacdza %0" : "+r" (ptr));
+ return ptr;
+}
+
+size_t keydb_sign(size_t ptr)
+{
+ asm volatile("pacdzb %0" : "+r" (ptr));
+ return ptr;
+}
+
+size_t keyg_sign(size_t ptr)
+{
+ /* output is encoded in the upper 32 bits */
+ size_t dest = 0;
+ size_t modifier = 0;
+
+ asm volatile("pacga %0, %1, %2" : "=r" (dest) : "r" (ptr), "r" (modifier));
+
+ return dest;
+}
+
diff --git a/tools/testing/selftests/arm64/pauth/helper.h b/tools/testing/selftests/arm64/pauth/helper.h
index f777f88acf0a..b3cf709e249d 100644
--- a/tools/testing/selftests/arm64/pauth/helper.h
+++ b/tools/testing/selftests/arm64/pauth/helper.h
@@ -4,7 +4,17 @@
#ifndef _HELPER_H_
#define _HELPER_H_
+#include <stdlib.h>
+
+
void pac_corruptor(void);
+/* PAuth sign a value with key ia and modifier value 0 */
+size_t keyia_sign(size_t val);
+size_t keyib_sign(size_t val);
+size_t keyda_sign(size_t val);
+size_t keydb_sign(size_t val);
+size_t keyg_sign(size_t val);
+
#endif
diff --git a/tools/testing/selftests/arm64/pauth/pac.c b/tools/testing/selftests/arm64/pauth/pac.c
index ed445050f621..cdbffa8bf61e 100644
--- a/tools/testing/selftests/arm64/pauth/pac.c
+++ b/tools/testing/selftests/arm64/pauth/pac.c
@@ -12,12 +12,25 @@
* future version of the arm architecture
*/
+#define PAC_COLLISION_ATTEMPTS 10
+/*
+ * The kernel sets TBID by default. So bits 55 and above should remain
+ * untouched no matter what.
+ * The VA space size is 48 bits. Bigger is opt-in.
+ */
+#define PAC_MASK (~0xff80ffffffffffff)
#define ASSERT_PAUTH_ENABLED() \
do { \
unsigned long hwcaps = getauxval(AT_HWCAP); \
/* data key instructions are not in NOP space. This prevents a SIGILL */ \
ASSERT_NE(0, hwcaps & HWCAP_PACA) TH_LOG("PAUTH not enabled"); \
} while (0)
+#define ASSERT_GENERIC_PAUTH_ENABLED() \
+do { \
+ unsigned long hwcaps = getauxval(AT_HWCAP); \
+ /* generic key instructions are not in NOP space. This prevents a SIGILL */ \
+ ASSERT_NE(0, hwcaps & HWCAP_PACG) TH_LOG("Generic PAUTH not enabled"); \
+} while (0)
/* check that a corrupted PAC results in SIGSEGV */
@@ -28,5 +41,43 @@ TEST_SIGNAL(corrupt_pac, SIGSEGV)
pac_corruptor();
}
+/*
+ * There are no separate pac* and aut* controls so checking only the pac*
+ * instructions is sufficient
+ */
+TEST(pac_instructions_not_nop)
+{
+ size_t keyia = 0;
+ size_t keyib = 0;
+ size_t keyda = 0;
+ size_t keydb = 0;
+
+ ASSERT_PAUTH_ENABLED();
+
+ for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) {
+ keyia |= keyia_sign(i) & PAC_MASK;
+ keyib |= keyib_sign(i) & PAC_MASK;
+ keyda |= keyda_sign(i) & PAC_MASK;
+ keydb |= keydb_sign(i) & PAC_MASK;
+ }
+
+ ASSERT_NE(0, keyia) TH_LOG("keyia instructions did nothing");
+ ASSERT_NE(0, keyib) TH_LOG("keyib instructions did nothing");
+ ASSERT_NE(0, keyda) TH_LOG("keyda instructions did nothing");
+ ASSERT_NE(0, keydb) TH_LOG("keydb instructions did nothing");
+}
+
+TEST(pac_instructions_not_nop_generic)
+{
+ size_t keyg = 0;
+
+ ASSERT_GENERIC_PAUTH_ENABLED();
+
+ for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++)
+ keyg |= keyg_sign(i) & PAC_MASK;
+
+ ASSERT_NE(0, keyg) TH_LOG("keyg instructions did nothing");
+}
+
TEST_HARNESS_MAIN
--
2.17.1
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