From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amit Daniel Kachhap Subject: [PATCH v5 5/5] arm64/kvm: control accessibility of ptrauth key registers Date: Mon, 28 Jan 2019 12:28:46 +0530 Message-ID: <1548658727-14271-6-git-send-email-amit.kachhap@arm.com> References: <1548658727-14271-1-git-send-email-amit.kachhap@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A4AAE4A3C7 for ; Mon, 28 Jan 2019 01:59:36 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id VB3SEHg0qEtm for ; Mon, 28 Jan 2019 01:59:35 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3F1C14A422 for ; Mon, 28 Jan 2019 01:59:35 -0500 (EST) In-Reply-To: <1548658727-14271-1-git-send-email-amit.kachhap@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: linux-arm-kernel@lists.infradead.org Cc: Marc Zyngier , Catalin Marinas , Will Deacon , Kristina Martsenko , kvmarm@lists.cs.columbia.edu, Ramana Radhakrishnan , Amit Daniel Kachhap , Dave Martin , linux-kernel@vger.kernel.org List-Id: kvmarm@lists.cs.columbia.edu According to userspace settings, ptrauth key registers are conditionally present in guest system register list based on user specified flag KVM_ARM_VCPU_PTRAUTH. Signed-off-by: Amit Daniel Kachhap Cc: Mark Rutland Cc: Christoffer Dall Cc: Marc Zyngier Cc: Kristina Martsenko Cc: kvmarm@lists.cs.columbia.edu Cc: Ramana Radhakrishnan Cc: Will Deacon --- Documentation/arm64/pointer-authentication.txt | 3 ++ arch/arm64/kvm/sys_regs.c | 42 +++++++++++++++++++------- 2 files changed, 34 insertions(+), 11 deletions(-) diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt index 0529a7d..3be4ee1 100644 --- a/Documentation/arm64/pointer-authentication.txt +++ b/Documentation/arm64/pointer-authentication.txt @@ -87,3 +87,6 @@ created by passing a flag (KVM_ARM_VCPU_PTRAUTH) requesting this feature to be enabled. Without this flag, pointer authentication is not enabled in KVM guests and attempted use of the feature will result in an UNDEFINED exception being injected into the guest. + +Additionally, when KVM_ARM_VCPU_PTRAUTH is not set then KVM will filter +out the authentication key registers from userspace. diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 2546a65..b46a78e 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1334,12 +1334,6 @@ static const struct sys_reg_desc sys_reg_descs[] = { { SYS_DESC(SYS_TTBR1_EL1), access_vm_reg, reset_unknown, TTBR1_EL1 }, { SYS_DESC(SYS_TCR_EL1), access_vm_reg, reset_val, TCR_EL1, 0 }, - PTRAUTH_KEY(APIA), - PTRAUTH_KEY(APIB), - PTRAUTH_KEY(APDA), - PTRAUTH_KEY(APDB), - PTRAUTH_KEY(APGA), - { SYS_DESC(SYS_AFSR0_EL1), access_vm_reg, reset_unknown, AFSR0_EL1 }, { SYS_DESC(SYS_AFSR1_EL1), access_vm_reg, reset_unknown, AFSR1_EL1 }, { SYS_DESC(SYS_ESR_EL1), access_vm_reg, reset_unknown, ESR_EL1 }, @@ -1491,6 +1485,14 @@ static const struct sys_reg_desc sys_reg_descs[] = { { SYS_DESC(SYS_FPEXC32_EL2), NULL, reset_val, FPEXC32_EL2, 0x70 }, }; +static const struct sys_reg_desc ptrauth_reg_descs[] = { + PTRAUTH_KEY(APIA), + PTRAUTH_KEY(APIB), + PTRAUTH_KEY(APDA), + PTRAUTH_KEY(APDB), + PTRAUTH_KEY(APGA), +}; + static bool trap_dbgidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p, const struct sys_reg_desc *r) @@ -2093,6 +2095,8 @@ static int emulate_sys_reg(struct kvm_vcpu *vcpu, r = find_reg(params, table, num); if (!r) r = find_reg(params, sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); + if (!r && kvm_arm_vcpu_ptrauth_allowed(vcpu)) + r = find_reg(params, ptrauth_reg_descs, ARRAY_SIZE(ptrauth_reg_descs)); if (likely(r)) { perform_access(vcpu, params, r); @@ -2206,6 +2210,8 @@ static const struct sys_reg_desc *index_to_sys_reg_desc(struct kvm_vcpu *vcpu, r = find_reg_by_id(id, ¶ms, table, num); if (!r) r = find_reg(¶ms, sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); + if (!r && kvm_arm_vcpu_ptrauth_allowed(vcpu)) + r = find_reg(¶ms, ptrauth_reg_descs, ARRAY_SIZE(ptrauth_reg_descs)); /* Not saved in the sys_reg array and not otherwise accessible? */ if (r && !(r->reg || r->get_user)) @@ -2487,18 +2493,22 @@ static int walk_one_sys_reg(const struct sys_reg_desc *rd, } /* Assumed ordered tables, see kvm_sys_reg_table_init. */ -static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind) +static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind, + const struct sys_reg_desc *desc, unsigned int len) { const struct sys_reg_desc *i1, *i2, *end1, *end2; unsigned int total = 0; size_t num; int err; + if (desc == ptrauth_reg_descs && !kvm_arm_vcpu_ptrauth_allowed(vcpu)) + return total; + /* We check for duplicates here, to allow arch-specific overrides. */ i1 = get_target_table(vcpu->arch.target, true, &num); end1 = i1 + num; - i2 = sys_reg_descs; - end2 = sys_reg_descs + ARRAY_SIZE(sys_reg_descs); + i2 = desc; + end2 = desc + len; BUG_ON(i1 == end1 || i2 == end2); @@ -2526,7 +2536,10 @@ unsigned long kvm_arm_num_sys_reg_descs(struct kvm_vcpu *vcpu) { return ARRAY_SIZE(invariant_sys_regs) + num_demux_regs() - + walk_sys_regs(vcpu, (u64 __user *)NULL); + + walk_sys_regs(vcpu, (u64 __user *)NULL, sys_reg_descs, + ARRAY_SIZE(sys_reg_descs)) + + walk_sys_regs(vcpu, (u64 __user *)NULL, ptrauth_reg_descs, + ARRAY_SIZE(ptrauth_reg_descs)); } int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) @@ -2541,7 +2554,12 @@ int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) uindices++; } - err = walk_sys_regs(vcpu, uindices); + err = walk_sys_regs(vcpu, uindices, sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); + if (err < 0) + return err; + uindices += err; + + err = walk_sys_regs(vcpu, uindices, ptrauth_reg_descs, ARRAY_SIZE(ptrauth_reg_descs)); if (err < 0) return err; uindices += err; @@ -2575,6 +2593,7 @@ void kvm_sys_reg_table_init(void) BUG_ON(check_sysreg_table(cp15_regs, ARRAY_SIZE(cp15_regs))); BUG_ON(check_sysreg_table(cp15_64_regs, ARRAY_SIZE(cp15_64_regs))); BUG_ON(check_sysreg_table(invariant_sys_regs, ARRAY_SIZE(invariant_sys_regs))); + BUG_ON(check_sysreg_table(ptrauth_reg_descs, ARRAY_SIZE(ptrauth_reg_descs))); /* We abuse the reset function to overwrite the table itself. */ for (i = 0; i < ARRAY_SIZE(invariant_sys_regs); i++) @@ -2616,6 +2635,7 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu) /* Generic chip reset first (so target could override). */ reset_sys_reg_descs(vcpu, sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); + reset_sys_reg_descs(vcpu, ptrauth_reg_descs, ARRAY_SIZE(ptrauth_reg_descs)); table = get_target_table(vcpu->arch.target, true, &num); reset_sys_reg_descs(vcpu, table, num); -- 2.7.4