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KVM: x86: check CS.DPL against RPL during task switch

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Table 7-1 of the SDM mentions a check that the code segment's
DPL must match the selector's RPL.  This was not done by KVM,
fix it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-05-15 18:09:29 +02:00
parent fb5e336b97
commit 5045b46803
1 changed files with 17 additions and 14 deletions
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31
arch/x86/kvm/emulate.c
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@ -1411,7 +1411,7 @@ static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
/* Does not support long mode */ /* Does not support long mode */
static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
u16 selector, int seg, u8 cpl) u16 selector, int seg, u8 cpl, bool in_task_switch)
{ {
struct desc_struct seg_desc, old_desc; struct desc_struct seg_desc, old_desc;
u8 dpl, rpl; u8 dpl, rpl;
@ -1486,6 +1486,9 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
goto exception; goto exception;
break; break;
case VCPU_SREG_CS: case VCPU_SREG_CS:
if (in_task_switch && rpl != dpl)
goto exception;
if (!(seg_desc.type & 8)) if (!(seg_desc.type & 8))
goto exception; goto exception;
@ -1547,7 +1550,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
u16 selector, int seg) u16 selector, int seg)
{ {
u8 cpl = ctxt->ops->cpl(ctxt); u8 cpl = ctxt->ops->cpl(ctxt);
return __load_segment_descriptor(ctxt, selector, seg, cpl); return __load_segment_descriptor(ctxt, selector, seg, cpl, false);
} }
static void write_register_operand(struct operand *op) static void write_register_operand(struct operand *op)
@ -2440,19 +2443,19 @@ static int load_state_from_tss16(struct x86_emulate_ctxt *ctxt,
* Now load segment descriptors. If fault happens at this stage * Now load segment descriptors. If fault happens at this stage
* it is handled in a context of new task * it is handled in a context of new task
*/ */
ret = __load_segment_descriptor(ctxt, tss->ldt, VCPU_SREG_LDTR, cpl); ret = __load_segment_descriptor(ctxt, tss->ldt, VCPU_SREG_LDTR, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl); ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl); ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl); ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl); ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
@ -2577,25 +2580,25 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt,
* Now load segment descriptors. If fault happenes at this stage * Now load segment descriptors. If fault happenes at this stage
* it is handled in a context of new task * it is handled in a context of new task
*/ */
ret = __load_segment_descriptor(ctxt, tss->ldt_selector, VCPU_SREG_LDTR, cpl); ret = __load_segment_descriptor(ctxt, tss->ldt_selector, VCPU_SREG_LDTR, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl); ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl); ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl); ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl); ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->fs, VCPU_SREG_FS, cpl); ret = __load_segment_descriptor(ctxt, tss->fs, VCPU_SREG_FS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;
ret = __load_segment_descriptor(ctxt, tss->gs, VCPU_SREG_GS, cpl); ret = __load_segment_descriptor(ctxt, tss->gs, VCPU_SREG_GS, cpl, true);
if (ret != X86EMUL_CONTINUE) if (ret != X86EMUL_CONTINUE)
return ret; return ret;