From: Kristina Martsenko <kristina.martsenko@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Adam Wallis <awallis@codeaurora.org>,
Amit Kachhap <Amit.Kachhap@arm.com>,
Andrew Jones <drjones@redhat.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Arnd Bergmann <arnd@arndb.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Christoffer Dall <christoffer.dall@arm.com>,
Dave P Martin <Dave.Martin@arm.com>,
Jacob Bramley <jacob.bramley@arm.com>,
Kees Cook <keescook@chromium.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
"Suzuki K . Poulose" <suzuki.poulose@arm.com>,
Will Deacon <will.deacon@arm.com>,
kvmarm@lists.cs.columbia.edu, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v5 08/17] arm64: expose user PAC bit positions via ptrace
Date: Fri, 5 Oct 2018 09:47:45 +0100 [thread overview]
Message-ID: <20181005084754.20950-9-kristina.martsenko@arm.com> (raw)
Message-ID: <20181005084745.Kp-INKWJfeXYIXqpVHhQwslwVJUPJX7LDBKqjBTQfiE@z> (raw)
In-Reply-To: <20181005084754.20950-1-kristina.martsenko@arm.com>
From: Mark Rutland <mark.rutland@arm.com>
When pointer authentication is in use, data/instruction pointers have a
number of PAC bits inserted into them. The number and position of these
bits depends on the configured TCR_ELx.TxSZ and whether tagging is
enabled. ARMv8.3 allows tagging to differ for instruction and data
pointers.
For userspace debuggers to unwind the stack and/or to follow pointer
chains, they need to be able to remove the PAC bits before attempting to
use a pointer.
This patch adds a new structure with masks describing the location of
the PAC bits in userspace instruction and data pointers (i.e. those
addressable via TTBR0), which userspace can query via PTRACE_GETREGSET.
By clearing these bits from pointers (and replacing them with the value
of bit 55), userspace can acquire the PAC-less versions.
This new regset is exposed when the kernel is built with (user) pointer
authentication support, and the feature is enabled. Otherwise, it is
hidden.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
[kristina: cpus_have_cap -> cpus_have_const_cap]
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/pointer_auth.h | 8 ++++++++
arch/arm64/include/uapi/asm/ptrace.h | 7 +++++++
arch/arm64/kernel/ptrace.c | 38 +++++++++++++++++++++++++++++++++++
include/uapi/linux/elf.h | 1 +
4 files changed, 54 insertions(+)
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index 2aefedc31d9e..15486079e9ec 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -2,9 +2,11 @@
#ifndef __ASM_POINTER_AUTH_H
#define __ASM_POINTER_AUTH_H
+#include <linux/bitops.h>
#include <linux/random.h>
#include <asm/cpufeature.h>
+#include <asm/memory.h>
#include <asm/sysreg.h>
#ifdef CONFIG_ARM64_PTR_AUTH
@@ -49,6 +51,12 @@ static inline void ptrauth_keys_switch(struct ptrauth_keys *keys)
__ptrauth_key_install(APIA, keys->apia);
}
+/*
+ * The EL0 pointer bits used by a pointer authentication code.
+ * This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
+ */
+#define ptrauth_pac_mask() GENMASK(54, VA_BITS)
+
#define mm_ctx_ptrauth_init(ctx) \
ptrauth_keys_init(&(ctx)->ptrauth_keys)
diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 98c4ce55d9c3..4994d718771a 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -228,6 +228,13 @@ struct user_sve_header {
SVE_PT_SVE_OFFSET + SVE_PT_SVE_SIZE(vq, flags) \
: SVE_PT_FPSIMD_OFFSET + SVE_PT_FPSIMD_SIZE(vq, flags))
+/* pointer authentication masks (NT_ARM_PAC_MASK) */
+
+struct user_pac_mask {
+ __u64 data_mask;
+ __u64 insn_mask;
+};
+
#endif /* __ASSEMBLY__ */
#endif /* _UAPI__ASM_PTRACE_H */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 6219486fa25f..cb8246f8c603 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -46,6 +46,7 @@
#include <asm/debug-monitors.h>
#include <asm/fpsimd.h>
#include <asm/pgtable.h>
+#include <asm/pointer_auth.h>
#include <asm/stacktrace.h>
#include <asm/syscall.h>
#include <asm/traps.h>
@@ -958,6 +959,30 @@ static int sve_set(struct task_struct *target,
#endif /* CONFIG_ARM64_SVE */
+#ifdef CONFIG_ARM64_PTR_AUTH
+static int pac_mask_get(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf)
+{
+ /*
+ * The PAC bits can differ across data and instruction pointers
+ * depending on TCR_EL1.TBID*, which we may make use of in future, so
+ * we expose separate masks.
+ */
+ unsigned long mask = ptrauth_pac_mask();
+ struct user_pac_mask uregs = {
+ .data_mask = mask,
+ .insn_mask = mask,
+ };
+
+ if (!cpus_have_const_cap(ARM64_HAS_ADDRESS_AUTH))
+ return -EINVAL;
+
+ return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &uregs, 0, -1);
+}
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
enum aarch64_regset {
REGSET_GPR,
REGSET_FPR,
@@ -970,6 +995,9 @@ enum aarch64_regset {
#ifdef CONFIG_ARM64_SVE
REGSET_SVE,
#endif
+#ifdef CONFIG_ARM64_PTR_AUTH
+ REGSET_PAC_MASK,
+#endif
};
static const struct user_regset aarch64_regsets[] = {
@@ -1039,6 +1067,16 @@ static const struct user_regset aarch64_regsets[] = {
.get_size = sve_get_size,
},
#endif
+#ifdef CONFIG_ARM64_PTR_AUTH
+ [REGSET_PAC_MASK] = {
+ .core_note_type = NT_ARM_PAC_MASK,
+ .n = sizeof(struct user_pac_mask) / sizeof(u64),
+ .size = sizeof(u64),
+ .align = sizeof(u64),
+ .get = pac_mask_get,
+ /* this cannot be set dynamically */
+ },
+#endif
};
static const struct user_regset_view user_aarch64_view = {
diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index c5358e0ae7c5..3f23273d690c 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -420,6 +420,7 @@ typedef struct elf64_shdr {
#define NT_ARM_HW_WATCH 0x403 /* ARM hardware watchpoint registers */
#define NT_ARM_SYSTEM_CALL 0x404 /* ARM system call number */
#define NT_ARM_SVE 0x405 /* ARM Scalable Vector Extension registers */
+#define NT_ARM_PAC_MASK 0x406 /* ARM pointer authentication code masks */
#define NT_ARC_V2 0x600 /* ARCv2 accumulator/extra registers */
#define NT_VMCOREDD 0x700 /* Vmcore Device Dump Note */
#define NT_MIPS_DSP 0x800 /* MIPS DSP ASE registers */
--
2.11.0
next prev parent reply other threads:[~2018-10-05 15:48 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-05 8:47 [PATCH 00/17] ARMv8.3 pointer authentication support Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 01/17] arm64: add pointer authentication register bits Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-11 16:28 ` Will Deacon
2018-10-11 16:28 ` Will Deacon
2018-10-12 8:53 ` Mark Rutland
2018-10-12 8:53 ` Mark Rutland
2018-10-12 8:56 ` Will Deacon
2018-10-12 8:56 ` Will Deacon
2018-10-12 9:50 ` Mark Rutland
2018-10-12 9:50 ` Mark Rutland
2018-10-05 8:47 ` [PATCH v5 02/17] arm64/kvm: consistently handle host HCR_EL2 flags Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 03/17] arm64/kvm: hide ptrauth from guests Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 04/17] arm64: Don't trap host pointer auth use to EL2 Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 05/17] arm64/cpufeature: detect pointer authentication Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 06/17] asm-generic: mm_hooks: allow hooks to be overridden individually Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 07/17] arm64: add basic pointer authentication support Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-11 16:00 ` Suzuki K Poulose
2018-10-11 16:00 ` Suzuki K Poulose
2018-10-19 11:15 ` Catalin Marinas
2018-10-19 11:15 ` Catalin Marinas
2018-10-19 11:24 ` Will Deacon
2018-10-19 11:24 ` Will Deacon
2018-10-19 15:36 ` Kees Cook
2018-10-19 15:36 ` Kees Cook
2018-10-19 15:49 ` Will Deacon
2018-10-19 15:49 ` Will Deacon
2018-10-19 16:05 ` Kees Cook
2018-10-19 16:05 ` Kees Cook
2018-10-19 16:16 ` Will Deacon
2018-10-19 16:16 ` Will Deacon
2018-10-19 15:54 ` Mark Rutland
2018-10-19 15:54 ` Mark Rutland
2018-10-19 16:49 ` Cyrill Gorcunov
2018-10-19 16:49 ` Cyrill Gorcunov
2018-11-14 18:11 ` Will Deacon
2018-11-14 18:11 ` Will Deacon
2018-11-15 10:25 ` Dave Martin
2018-11-15 10:25 ` Dave Martin
2018-10-23 8:36 ` Ramana Radhakrishnan
2018-10-23 8:36 ` Ramana Radhakrishnan
2018-10-23 10:20 ` Will Deacon
2018-10-23 10:20 ` Will Deacon
2018-10-05 8:47 ` Kristina Martsenko [this message]
2018-10-05 8:47 ` [PATCH v5 08/17] arm64: expose user PAC bit positions via ptrace Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 09/17] arm64: perf: strip PAC when unwinding userspace Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 10/17] arm64: enable pointer authentication Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [PATCH v5 11/17] arm64: docs: document " Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 9:04 ` Ramana Radhakrishnan
2018-10-05 9:04 ` Ramana Radhakrishnan
2018-10-16 16:14 ` Kristina Martsenko
2018-10-16 16:14 ` Kristina Martsenko
2018-10-19 11:35 ` Catalin Marinas
2018-10-19 11:35 ` Catalin Marinas
2018-10-19 11:47 ` Marc Zyngier
2018-10-19 11:47 ` Marc Zyngier
2018-10-19 12:22 ` Will Deacon
2018-10-19 12:22 ` Will Deacon
2018-10-19 14:42 ` Kristina Martsenko
2018-10-19 14:42 ` Kristina Martsenko
2018-10-19 15:10 ` Catalin Marinas
2018-10-19 15:10 ` Catalin Marinas
2018-10-19 17:45 ` Will Deacon
2018-10-19 17:45 ` Will Deacon
2018-11-02 6:02 ` Jon Masters
2018-11-02 6:02 ` Jon Masters
2018-10-24 10:56 ` Ramana Radhakrishnan
2018-10-24 10:56 ` Ramana Radhakrishnan
2018-10-15 22:35 ` Kees Cook
2018-10-15 22:35 ` Kees Cook
2018-11-02 9:46 ` Ramana Radhakrishnan
2018-11-02 9:46 ` Ramana Radhakrishnan
2018-10-05 8:47 ` [RFC 12/17] arm64: move ptrauth keys to thread_info Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-19 11:38 ` Catalin Marinas
2018-10-19 11:38 ` Catalin Marinas
2018-10-05 8:47 ` [RFC 13/17] arm64: install user ptrauth keys at kernel exit time Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [RFC 14/17] arm64: unwind: strip PAC from kernel addresses Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 8:47 ` [RFC 15/17] arm64: enable ptrauth earlier Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-06 12:51 ` Amit Kachhap
2018-10-06 12:51 ` Amit Kachhap
2018-10-05 8:47 ` [RFC 16/17] arm64: initialize and switch ptrauth kernel keys Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-06 12:56 ` Amit Kachhap
2018-10-06 12:56 ` Amit Kachhap
2018-10-05 8:47 ` [RFC 17/17] arm64: compile the kernel with ptrauth -msign-return-address Kristina Martsenko
2018-10-05 8:47 ` Kristina Martsenko
2018-10-05 9:01 ` Ramana Radhakrishnan
2018-10-05 9:01 ` Ramana Radhakrishnan
2018-10-11 14:00 ` Kristina Martsenko
2018-10-11 14:00 ` Kristina Martsenko
2018-10-11 14:23 ` Vladimir Murzin
2018-10-11 14:23 ` Vladimir Murzin
2018-10-15 22:38 ` Kees Cook
2018-10-15 22:38 ` Kees Cook
2018-10-15 22:42 ` [PATCH 00/17] ARMv8.3 pointer authentication support Kees Cook
2018-10-15 22:42 ` Kees Cook
2018-11-13 16:17 ` Kristina Martsenko
2018-11-13 16:17 ` Kristina Martsenko
2018-11-13 23:09 ` Kees Cook
2018-11-13 23:09 ` Kees Cook
2018-11-14 15:54 ` Kristina Martsenko
2018-11-14 15:54 ` Kristina Martsenko
2018-11-14 21:47 ` Mark Rutland
2018-11-14 21:47 ` Mark Rutland
2018-11-14 22:48 ` Kees Cook
2018-11-14 22:48 ` Kees Cook
2018-10-19 12:36 ` Will Deacon
2018-10-19 12:36 ` Will Deacon
2018-10-23 8:39 ` Ramana Radhakrishnan
2018-10-23 8:39 ` Ramana Radhakrishnan
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