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Wed, 29 Jul 2026 05:13:49 -0700 (PDT) Date: Wed, 29 Jul 2026 12:13:07 +0000 In-Reply-To: <20260729121306.1519473-2-sebastianene@google.com> Mime-Version: 1.0 References: <20260729121306.1519473-2-sebastianene@google.com> X-Mailer: git-send-email 2.55.0.487.gaf234c4eb3-goog Message-ID: <20260729121306.1519473-9-sebastianene@google.com> Subject: [PATCH v8 7/7] KVM: arm64: Enforce strict SBZ checks in the FF-A proxy From: Sebastian Ene To: catalin.marinas@arm.com, maz@kernel.org, oupton@kernel.org, fuad.tabba@linux.dev, will@kernel.org Cc: joey.gouly@arm.com, korneld@google.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, mrigendra.chaubey@gmail.com, perlarsen@google.com, sebastianene@google.com, suzuki.poulose@arm.com, vdonnefort@google.com, yuzenghui@huawei.com Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260729_051352_122837_C107CF90 X-CRM114-Status: GOOD ( 15.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Introduce a helper method ffa_check_unused_args_sbz to enforce strict arguments checking when the hypervisor acts as a relayer between the host and Trustzone. Reviewed-by: Vincent Donnefort Acked-by: Will Deacon Signed-off-by: Sebastian Ene --- arch/arm64/kvm/hyp/nvhe/ffa.c | 96 ++++++++++++++++++++++++++++++++++- 1 file changed, 95 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c index 712811e89435..334f8a28d942 100644 --- a/arch/arm64/kvm/hyp/nvhe/ffa.c +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c @@ -74,6 +74,21 @@ static u32 hyp_ffa_version; static bool has_version_negotiated; static hyp_spinlock_t version_lock; +static bool ffa_check_unused_args_sbz(struct kvm_cpu_context *ctxt, int first_reg) +{ + DECLARE_REG(u32, func_id, ctxt, 0); + int reg, end_reg = 7; + + if (hyp_ffa_version >= FFA_VERSION_1_2 && ARM_SMCCC_IS_64(func_id)) + end_reg = 17; + for (reg = first_reg; reg <= end_reg; reg++) { + if (cpu_reg(ctxt, reg)) + return true; + } + + return false; +} + static void ffa_to_smccc_error(struct arm_smccc_1_2_regs *res, u64 ffa_errno) { *res = (struct arm_smccc_1_2_regs) { @@ -242,6 +257,11 @@ static void do_ffa_rxtx_map(struct arm_smccc_1_2_regs *res, int ret = 0; void *rx_virt, *tx_virt; + if (ffa_check_unused_args_sbz(ctxt, 4)) { + ret = FFA_RET_INVALID_PARAMETERS; + goto out; + } + if (npages != (KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) / FFA_PAGE_SIZE) { ret = FFA_RET_INVALID_PARAMETERS; goto out; @@ -318,6 +338,11 @@ static void do_ffa_rxtx_unmap(struct arm_smccc_1_2_regs *res, DECLARE_REG(u32, id, ctxt, 1); int ret = 0; + if (ffa_check_unused_args_sbz(ctxt, 2)) { + ret = FFA_RET_INVALID_PARAMETERS; + goto out; + } + if (id != HOST_FFA_ID) { ret = FFA_RET_INVALID_PARAMETERS; goto out; @@ -424,6 +449,11 @@ static void do_ffa_mem_frag_tx(struct arm_smccc_1_2_regs *res, int ret = FFA_RET_INVALID_PARAMETERS; u32 nr_ranges; + if (ffa_check_unused_args_sbz(ctxt, 5)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + if (fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) goto out; @@ -485,6 +515,11 @@ static void __do_ffa_mem_xfer(const u64 func_id, u32 offset, nr_ranges, checked_offset; int ret = 0; + if (ffa_check_unused_args_sbz(ctxt, 5)) { + ret = FFA_RET_INVALID_PARAMETERS; + goto out; + } + if (addr_mbz || npages_mbz || fraglen > len || fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) { ret = FFA_RET_INVALID_PARAMETERS; @@ -584,6 +619,11 @@ static void do_ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, int ret = 0; u64 handle; + if (ffa_check_unused_args_sbz(ctxt, 4)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + handle = PACK_HANDLE(handle_lo, handle_hi); hyp_spin_lock(&host_buffers.lock); @@ -764,6 +804,11 @@ static void do_ffa_version(struct arm_smccc_1_2_regs *res, { DECLARE_REG(u32, ffa_req_version, ctxt, 1); + if (ffa_check_unused_args_sbz(ctxt, 2)) { + res->a0 = FFA_RET_NOT_SUPPORTED; + return; + } + if (FFA_MAJOR_VERSION(ffa_req_version) != 1) { res->a0 = FFA_RET_NOT_SUPPORTED; return; @@ -813,6 +858,11 @@ static void do_ffa_part_get(struct arm_smccc_1_2_regs *res, DECLARE_REG(u32, flags, ctxt, 5); u32 count, partition_sz, copy_sz; + if (ffa_check_unused_args_sbz(ctxt, 6)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + hyp_spin_lock(&host_buffers.lock); if (!host_buffers.rx) { ffa_to_smccc_res(res, FFA_RET_BUSY); @@ -860,9 +910,15 @@ static void do_ffa_part_get(struct arm_smccc_1_2_regs *res, static void do_ffa_notif_bitmap(struct arm_smccc_1_2_regs *res, struct kvm_cpu_context *ctxt) { + DECLARE_REG(u32, func_id, ctxt, 0); DECLARE_REG(u32, vmid, ctxt, 1); struct arm_smccc_1_2_regs *args; + if (ffa_check_unused_args_sbz(ctxt, func_id == FFA_NOTIFICATION_BITMAP_CREATE ? 3 : 2)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + if (vmid != HOST_FFA_ID) { ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); return; @@ -879,6 +935,11 @@ static void do_ffa_notif_bind(struct arm_smccc_1_2_regs *res, DECLARE_REG(u32, flags, ctxt, 2); struct arm_smccc_1_2_regs *args; + if (ffa_check_unused_args_sbz(ctxt, 5)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + if (FIELD_GET(FFA_NOTIF_RECEIVER_ENDP_MASK, endp_id) != HOST_FFA_ID) { ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); return; @@ -900,7 +961,7 @@ static void do_ffa_notif_unbind(struct arm_smccc_1_2_regs *res, DECLARE_REG(u32, reserved, ctxt, 2); struct arm_smccc_1_2_regs *args; - if (reserved) { + if (ffa_check_unused_args_sbz(ctxt, 5) || reserved) { ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); return; } @@ -926,6 +987,11 @@ static void do_ffa_notif_set(struct arm_smccc_1_2_regs *res, return; } + if (ffa_check_unused_args_sbz(ctxt, 5)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + if (flags & GENMASK(15, 2)) { ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); return; @@ -947,6 +1013,11 @@ static void do_ffa_notif_get(struct arm_smccc_1_2_regs *res, return; } + if (ffa_check_unused_args_sbz(ctxt, 3)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + if (flags & GENMASK(31, 4)) { ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); return; @@ -956,6 +1027,20 @@ static void do_ffa_notif_get(struct arm_smccc_1_2_regs *res, hyp_smccc_1_2_smc(args, res); } +static void do_ffa_notif_info_get(struct arm_smccc_1_2_regs *res, + struct kvm_cpu_context *ctxt) +{ + struct arm_smccc_1_2_regs *args; + + if (ffa_check_unused_args_sbz(ctxt, 1)) { + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); + return; + } + + args = (void *)&ctxt->regs.regs[0]; + hyp_smccc_1_2_smc(args, res); +} + bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id) { struct arm_smccc_1_2_regs res; @@ -984,6 +1069,11 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id) switch (func_id) { case FFA_FEATURES: + if (ffa_check_unused_args_sbz(host_ctxt, 3)) { + ffa_to_smccc_res(&res, FFA_RET_INVALID_PARAMETERS); + goto out_handled; + } + if (!do_ffa_features(&res, host_ctxt)) return false; goto out_handled; @@ -1030,6 +1120,10 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id) case FFA_NOTIFICATION_GET: do_ffa_notif_get(&res, host_ctxt); goto out_handled; + case FFA_NOTIFICATION_INFO_GET: + case FFA_FN64_NOTIFICATION_INFO_GET: + do_ffa_notif_info_get(&res, host_ctxt); + goto out_handled; } if (ffa_call_supported(func_id)) -- 2.55.0.487.gaf234c4eb3-goog