From f850e2e603bf5a05b0aee7901857cf85715aa694 Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Wed, 10 Feb 2010 14:21:33 +0200 Subject: KVM: x86 emulator: Check IOPL level during io instruction emulation Make emulator check that vcpu is allowed to execute IN, INS, OUT, OUTS, CLI, STI. Signed-off-by: Gleb Natapov Cc: stable@kernel.org Signed-off-by: Avi Kivity diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index c07c16f..f9a2f66 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -678,6 +678,7 @@ void kvm_disable_tdp(void); int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3); int complete_pio(struct kvm_vcpu *vcpu); +bool kvm_check_iopl(struct kvm_vcpu *vcpu); struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn); diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index c44b460..296e851 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1698,6 +1698,57 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt) return 0; } +static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt) +{ + int iopl; + if (ctxt->mode == X86EMUL_MODE_REAL) + return false; + if (ctxt->mode == X86EMUL_MODE_VM86) + return true; + iopl = (ctxt->eflags & X86_EFLAGS_IOPL) >> IOPL_SHIFT; + return kvm_x86_ops->get_cpl(ctxt->vcpu) > iopl; +} + +static bool emulator_io_port_access_allowed(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops *ops, + u16 port, u16 len) +{ + struct kvm_segment tr_seg; + int r; + u16 io_bitmap_ptr; + u8 perm, bit_idx = port & 0x7; + unsigned mask = (1 << len) - 1; + + kvm_get_segment(ctxt->vcpu, &tr_seg, VCPU_SREG_TR); + if (tr_seg.unusable) + return false; + if (tr_seg.limit < 103) + return false; + r = ops->read_std(tr_seg.base + 102, &io_bitmap_ptr, 2, ctxt->vcpu, + NULL); + if (r != X86EMUL_CONTINUE) + return false; + if (io_bitmap_ptr + port/8 > tr_seg.limit) + return false; + r = ops->read_std(tr_seg.base + io_bitmap_ptr + port/8, &perm, 1, + ctxt->vcpu, NULL); + if (r != X86EMUL_CONTINUE) + return false; + if ((perm >> bit_idx) & mask) + return false; + return true; +} + +static bool emulator_io_permited(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops *ops, + u16 port, u16 len) +{ + if (emulator_bad_iopl(ctxt)) + if (!emulator_io_port_access_allowed(ctxt, ops, port, len)) + return false; + return true; +} + int x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) { @@ -1889,7 +1940,12 @@ special_insn: break; case 0x6c: /* insb */ case 0x6d: /* insw/insd */ - if (kvm_emulate_pio_string(ctxt->vcpu, + if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX], + (c->d & ByteOp) ? 1 : c->op_bytes)) { + kvm_inject_gp(ctxt->vcpu, 0); + goto done; + } + if (kvm_emulate_pio_string(ctxt->vcpu, 1, (c->d & ByteOp) ? 1 : c->op_bytes, c->rep_prefix ? @@ -1905,6 +1961,11 @@ special_insn: return 0; case 0x6e: /* outsb */ case 0x6f: /* outsw/outsd */ + if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX], + (c->d & ByteOp) ? 1 : c->op_bytes)) { + kvm_inject_gp(ctxt->vcpu, 0); + goto done; + } if (kvm_emulate_pio_string(ctxt->vcpu, 0, (c->d & ByteOp) ? 1 : c->op_bytes, @@ -2202,7 +2263,13 @@ special_insn: case 0xef: /* out (e/r)ax,dx */ port = c->regs[VCPU_REGS_RDX]; io_dir_in = 0; - do_io: if (kvm_emulate_pio(ctxt->vcpu, io_dir_in, + do_io: + if (!emulator_io_permited(ctxt, ops, port, + (c->d & ByteOp) ? 1 : c->op_bytes)) { + kvm_inject_gp(ctxt->vcpu, 0); + goto done; + } + if (kvm_emulate_pio(ctxt->vcpu, io_dir_in, (c->d & ByteOp) ? 1 : c->op_bytes, port) != 0) { c->eip = saved_eip; @@ -2227,13 +2294,21 @@ special_insn: c->dst.type = OP_NONE; /* Disable writeback. */ break; case 0xfa: /* cli */ - ctxt->eflags &= ~X86_EFLAGS_IF; - c->dst.type = OP_NONE; /* Disable writeback. */ + if (emulator_bad_iopl(ctxt)) + kvm_inject_gp(ctxt->vcpu, 0); + else { + ctxt->eflags &= ~X86_EFLAGS_IF; + c->dst.type = OP_NONE; /* Disable writeback. */ + } break; case 0xfb: /* sti */ - toggle_interruptibility(ctxt, X86_SHADOW_INT_STI); - ctxt->eflags |= X86_EFLAGS_IF; - c->dst.type = OP_NONE; /* Disable writeback. */ + if (emulator_bad_iopl(ctxt)) + kvm_inject_gp(ctxt->vcpu, 0); + else { + toggle_interruptibility(ctxt, X86_SHADOW_INT_STI); + ctxt->eflags |= X86_EFLAGS_IF; + c->dst.type = OP_NONE; /* Disable writeback. */ + } break; case 0xfc: /* cld */ ctxt->eflags &= ~EFLG_DF; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ea3a8af..86b739f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3599,6 +3599,8 @@ int kvm_emulate_pio(struct kvm_vcpu *vcpu, int in, int size, unsigned port) { unsigned long val; + trace_kvm_pio(!in, port, size, 1); + vcpu->run->exit_reason = KVM_EXIT_IO; vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT; vcpu->run->io.size = vcpu->arch.pio.size = size; @@ -3610,9 +3612,6 @@ int kvm_emulate_pio(struct kvm_vcpu *vcpu, int in, int size, unsigned port) vcpu->arch.pio.down = 0; vcpu->arch.pio.rep = 0; - trace_kvm_pio(vcpu->run->io.direction == KVM_EXIT_IO_OUT, port, - size, 1); - if (!vcpu->arch.pio.in) { val = kvm_register_read(vcpu, VCPU_REGS_RAX); memcpy(vcpu->arch.pio_data, &val, 4); @@ -3633,6 +3632,8 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, int in, unsigned now, in_page; int ret = 0; + trace_kvm_pio(!in, port, size, count); + vcpu->run->exit_reason = KVM_EXIT_IO; vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT; vcpu->run->io.size = vcpu->arch.pio.size = size; @@ -3644,9 +3645,6 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, int in, vcpu->arch.pio.down = down; vcpu->arch.pio.rep = rep; - trace_kvm_pio(vcpu->run->io.direction == KVM_EXIT_IO_OUT, port, - size, count); - if (!count) { kvm_x86_ops->skip_emulated_instruction(vcpu); return 1; -- cgit v0.10.2