From: Marc Zyngier <maz@kernel.org> To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: James Morse <james.morse@arm.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Oliver Upton <oliver.upton@linux.dev>, Zenghui Yu <yuzenghui@huawei.com>, Joey Gouly <joey.gouly@arm.com>, Fuad Tabba <tabba@google.com>, Mostafa Saleh <smostafa@google.com>, Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com> Subject: [PATCH v4 01/15] KVM: arm64: Harden __ctxt_sys_reg() against out-of-range values Date: Fri, 19 Apr 2024 11:29:21 +0100 [thread overview] Message-ID: <20240419102935.1935571-2-maz@kernel.org> (raw) In-Reply-To: <20240419102935.1935571-1-maz@kernel.org> The unsuspecting kernel tinkerer can be easily confused into writing something that looks like this: ikey.lo = __vcpu_sys_reg(vcpu, SYS_APIAKEYLO_EL1); which seems vaguely sensible, until you realise that the second parameter is the encoding of a sysreg, and not the index into the vcpu sysreg file... Debugging what happens in this case is an interesting exercise in head<->wall interactions. As they often say: "Any resemblance to actual persons, living or dead, or actual events is purely coincidental". In order to save people's time, add some compile-time hardening that will at least weed out the "stupidly out of range" values. This will *not* catch anything that isn't a compile-time constant. Reviewed-by: Joey Gouly <joey.gouly@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/include/asm/kvm_host.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 9e8a496fb284..e24bd876ec9a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -896,7 +896,7 @@ struct kvm_vcpu_arch { * Don't bother with VNCR-based accesses in the nVHE code, it has no * business dealing with NV. */ -static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) +static inline u64 *___ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) { #if !defined (__KVM_NVHE_HYPERVISOR__) if (unlikely(cpus_have_final_cap(ARM64_HAS_NESTED_VIRT) && @@ -906,6 +906,13 @@ static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) return (u64 *)&ctxt->sys_regs[r]; } +#define __ctxt_sys_reg(c,r) \ + ({ \ + BUILD_BUG_ON(__builtin_constant_p(r) && \ + (r) >= NR_SYS_REGS); \ + ___ctxt_sys_reg(c, r); \ + }) + #define ctxt_sys_reg(c,r) (*__ctxt_sys_reg(c,r)) u64 kvm_vcpu_sanitise_vncr_reg(const struct kvm_vcpu *, enum vcpu_sysreg); -- 2.39.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org> To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: James Morse <james.morse@arm.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Oliver Upton <oliver.upton@linux.dev>, Zenghui Yu <yuzenghui@huawei.com>, Joey Gouly <joey.gouly@arm.com>, Fuad Tabba <tabba@google.com>, Mostafa Saleh <smostafa@google.com>, Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com> Subject: [PATCH v4 01/15] KVM: arm64: Harden __ctxt_sys_reg() against out-of-range values Date: Fri, 19 Apr 2024 11:29:21 +0100 [thread overview] Message-ID: <20240419102935.1935571-2-maz@kernel.org> (raw) In-Reply-To: <20240419102935.1935571-1-maz@kernel.org> The unsuspecting kernel tinkerer can be easily confused into writing something that looks like this: ikey.lo = __vcpu_sys_reg(vcpu, SYS_APIAKEYLO_EL1); which seems vaguely sensible, until you realise that the second parameter is the encoding of a sysreg, and not the index into the vcpu sysreg file... Debugging what happens in this case is an interesting exercise in head<->wall interactions. As they often say: "Any resemblance to actual persons, living or dead, or actual events is purely coincidental". In order to save people's time, add some compile-time hardening that will at least weed out the "stupidly out of range" values. This will *not* catch anything that isn't a compile-time constant. Reviewed-by: Joey Gouly <joey.gouly@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/include/asm/kvm_host.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 9e8a496fb284..e24bd876ec9a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -896,7 +896,7 @@ struct kvm_vcpu_arch { * Don't bother with VNCR-based accesses in the nVHE code, it has no * business dealing with NV. */ -static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) +static inline u64 *___ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) { #if !defined (__KVM_NVHE_HYPERVISOR__) if (unlikely(cpus_have_final_cap(ARM64_HAS_NESTED_VIRT) && @@ -906,6 +906,13 @@ static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) return (u64 *)&ctxt->sys_regs[r]; } +#define __ctxt_sys_reg(c,r) \ + ({ \ + BUILD_BUG_ON(__builtin_constant_p(r) && \ + (r) >= NR_SYS_REGS); \ + ___ctxt_sys_reg(c, r); \ + }) + #define ctxt_sys_reg(c,r) (*__ctxt_sys_reg(c,r)) u64 kvm_vcpu_sanitise_vncr_reg(const struct kvm_vcpu *, enum vcpu_sysreg); -- 2.39.2
next prev parent reply other threads:[~2024-04-19 10:30 UTC|newest] Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-04-19 10:29 [PATCH v4 00/15] KVM/arm64: Add NV support for ERET and PAuth Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier [this message] 2024-04-19 10:29 ` [PATCH v4 01/15] KVM: arm64: Harden __ctxt_sys_reg() against out-of-range values Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 02/15] KVM: arm64: Add helpers for ESR_ELx_ERET_ISS_ERET* Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 03/15] KVM: arm64: Constraint PAuth support to consistent implementations Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 04/15] KVM: arm64: nv: Drop VCPU_HYP_CONTEXT flag Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 05/15] KVM: arm64: nv: Configure HCR_EL2 for FEAT_NV2 Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 06/15] KVM: arm64: nv: Add trap forwarding for ERET and SMC Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 07/15] KVM: arm64: nv: Fast-track 'InHost' exception returns Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 08/15] KVM: arm64: nv: Honor HFGITR_EL2.ERET being set Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 09/15] KVM: arm64: nv: Handle HCR_EL2.{API,APK} independently Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 10/15] KVM: arm64: nv: Reinject PAC exceptions caused by HCR_EL2.API==0 Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 11/15] KVM: arm64: nv: Add kvm_has_pauth() helper Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 12/15] KVM: arm64: nv: Add emulation for ERETAx instructions Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-23 9:22 ` Jon Hunter 2024-04-23 9:22 ` Jon Hunter 2024-04-23 9:40 ` Zenghui Yu 2024-04-23 9:40 ` Zenghui Yu 2024-04-23 11:42 ` Marc Zyngier 2024-04-23 11:42 ` Marc Zyngier 2024-04-23 12:30 ` Jon Hunter 2024-04-23 12:30 ` Jon Hunter 2024-04-23 12:09 ` Jon Hunter 2024-04-23 12:09 ` Jon Hunter 2024-04-19 10:29 ` [PATCH v4 13/15] KVM: arm64: nv: Handle ERETA[AB] instructions Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 14/15] KVM: arm64: nv: Advertise support for PAuth Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 10:29 ` [PATCH v4 15/15] KVM: arm64: Drop trapping of PAuth instructions/keys Marc Zyngier 2024-04-19 10:29 ` Marc Zyngier 2024-04-19 17:59 ` [PATCH v4 00/15] KVM/arm64: Add NV support for ERET and PAuth Oliver Upton 2024-04-19 17:59 ` Oliver Upton 2024-04-20 11:49 ` Marc Zyngier 2024-04-20 11:49 ` Marc Zyngier 2024-04-20 12:18 ` Marc Zyngier 2024-04-20 12:18 ` Marc Zyngier
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