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 03/17] arm64/kvm: hide ptrauth from guests
Date: Fri, 5 Oct 2018 09:47:40 +0100 [thread overview]
Message-ID: <20181005084754.20950-4-kristina.martsenko@arm.com> (raw)
Message-ID: <20181005084740.p00ACeWXUsDrzcc5qOXS3PhsgftjDpZlpgQ_68J95dg@z> (raw)
In-Reply-To: <20181005084754.20950-1-kristina.martsenko@arm.com>
From: Mark Rutland <mark.rutland@arm.com>
In subsequent patches we're going to expose ptrauth to the host kernel
and userspace, but things are a bit trickier for guest kernels. For the
time being, let's hide ptrauth from KVM guests.
Regardless of how well-behaved the guest kernel is, guest userspace
could attempt to use ptrauth instructions, triggering a trap to EL2,
resulting in noise from kvm_handle_unknown_ec(). So let's write up a
handler for the PAC trap, which silently injects an UNDEF into the
guest, as if the feature were really missing.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
[kristina: fix comment]
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
---
arch/arm64/kvm/handle_exit.c | 18 ++++++++++++++++++
arch/arm64/kvm/sys_regs.c | 8 ++++++++
2 files changed, 26 insertions(+)
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index e5e741bfffe1..53759b3c165d 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -173,6 +173,23 @@ static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run)
return 1;
}
+/*
+ * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into
+ * a NOP).
+ */
+static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+ /*
+ * We don't currently support ptrauth in a guest, and we mask the ID
+ * registers to prevent well-behaved guests from trying to make use of
+ * it.
+ *
+ * Inject an UNDEF, as if the feature really isn't present.
+ */
+ kvm_inject_undefined(vcpu);
+ return 1;
+}
+
static exit_handle_fn arm_exit_handlers[] = {
[0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
[ESR_ELx_EC_WFx] = kvm_handle_wfx,
@@ -195,6 +212,7 @@ static exit_handle_fn arm_exit_handlers[] = {
[ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug,
[ESR_ELx_EC_BRK64] = kvm_handle_guest_debug,
[ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd,
+ [ESR_ELx_EC_PAC] = kvm_handle_ptrauth,
};
static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 22fbbdbece3c..1ca592d38c3c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1040,6 +1040,14 @@ static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
kvm_debug("SVE unsupported for guests, suppressing\n");
val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT);
+ } else if (id == SYS_ID_AA64ISAR1_EL1) {
+ const u64 ptrauth_mask = (0xfUL << ID_AA64ISAR1_APA_SHIFT) |
+ (0xfUL << ID_AA64ISAR1_API_SHIFT) |
+ (0xfUL << ID_AA64ISAR1_GPA_SHIFT) |
+ (0xfUL << ID_AA64ISAR1_GPI_SHIFT);
+ if (val & ptrauth_mask)
+ kvm_debug("ptrauth unsupported for guests, suppressing\n");
+ val &= ~ptrauth_mask;
} else if (id == SYS_ID_AA64MMFR1_EL1) {
if (val & (0xfUL << ID_AA64MMFR1_LOR_SHIFT))
kvm_debug("LORegions unsupported for guests, suppressing\n");
--
2.11.0
next prev parent reply other threads:[~2018-10-05 15:47 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 ` Kristina Martsenko [this message]
2018-10-05 8:47 ` [PATCH v5 03/17] arm64/kvm: hide ptrauth from guests 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 ` [PATCH v5 08/17] arm64: expose user PAC bit positions via ptrace Kristina Martsenko
2018-10-05 8:47 ` 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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181005084754.20950-4-kristina.martsenko@arm.com \
--to=kristina.martsenko@arm.com \
--cc=Amit.Kachhap@arm.com \
--cc=Dave.Martin@arm.com \
--cc=ard.biesheuvel@linaro.org \
--cc=arnd@arndb.de \
--cc=awallis@codeaurora.org \
--cc=catalin.marinas@arm.com \
--cc=christoffer.dall@arm.com \
--cc=drjones@redhat.com \
--cc=jacob.bramley@arm.com \
--cc=keescook@chromium.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=mark.rutland@arm.com \
--cc=ramana.radhakrishnan@arm.com \
--cc=suzuki.poulose@arm.com \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).