| Message ID | 1366276617-3553-36-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
On Thu, 2013-04-18 at 10:16 +0100, Luis Henriques wrote: > 3.5.7.11 -stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Andy Honig <ahonig@google.com> > > commit 0b79459b482e85cb7426aa7da683a9f2c97aeae1 upstream. > > There is a potential use after free issue with the handling of > MSR_KVM_SYSTEM_TIME. If the guest specifies a GPA in a movable or removable > memory such as frame buffers then KVM might continue to write to that > address even after it's removed via KVM_SET_USER_MEMORY_REGION. KVM pins > the page in memory so it's unlikely to cause an issue, but if the user > space component re-purposes the memory previously used for the guest, then > the guest will be able to corrupt that memory. > > Tested: Tested against kvmclock unit test > > Signed-off-by: Andrew Honig <ahonig@google.com> > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> > [ luis: backported to 3.5: > - Adjust context > - Removed references to PVCLOCK_GUEST_STOPPED ] > Signed-off-by: Luis Henriques <luis.henriques@canonical.com> This apparently needs to be followed by commit 8f964525a121 'KVM: Allow cross page reads and writes from cached translations.', as some guests don't follow the rules. Ben. > --- > arch/x86/include/asm/kvm_host.h | 4 ++-- > arch/x86/kvm/x86.c | 40 +++++++++++++++------------------------- > 2 files changed, 17 insertions(+), 27 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index db7c1f2..9a50912 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -410,8 +410,8 @@ struct kvm_vcpu_arch { > gpa_t time; > struct pvclock_vcpu_time_info hv_clock; > unsigned int hw_tsc_khz; > - unsigned int time_offset; > - struct page *time_page; > + struct gfn_to_hva_cache pv_time; > + bool pv_time_enabled; > > struct { > u64 msr_val; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index ad5cf4b..5b4ac78 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1118,7 +1118,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > { > unsigned long flags; > struct kvm_vcpu_arch *vcpu = &v->arch; > - void *shared_kaddr; > unsigned long this_tsc_khz; > s64 kernel_ns, max_kernel_ns; > u64 tsc_timestamp; > @@ -1154,7 +1153,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > > local_irq_restore(flags); > > - if (!vcpu->time_page) > + if (!vcpu->pv_time_enabled) > return 0; > > /* > @@ -1212,14 +1211,9 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > */ > vcpu->hv_clock.version += 2; > > - shared_kaddr = kmap_atomic(vcpu->time_page); > - > - memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock, > - sizeof(vcpu->hv_clock)); > - > - kunmap_atomic(shared_kaddr); > - > - mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT); > + kvm_write_guest_cached(v->kvm, &vcpu->pv_time, > + &vcpu->hv_clock, > + sizeof(vcpu->hv_clock)); > return 0; > } > > @@ -1508,10 +1502,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) > > static void kvmclock_reset(struct kvm_vcpu *vcpu) > { > - if (vcpu->arch.time_page) { > - kvm_release_page_dirty(vcpu->arch.time_page); > - vcpu->arch.time_page = NULL; > - } > + vcpu->arch.pv_time_enabled = false; > } > > static void accumulate_steal_time(struct kvm_vcpu *vcpu) > @@ -1606,6 +1597,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) > break; > case MSR_KVM_SYSTEM_TIME_NEW: > case MSR_KVM_SYSTEM_TIME: { > + u64 gpa_offset; > kvmclock_reset(vcpu); > > vcpu->arch.time = data; > @@ -1615,21 +1607,18 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) > if (!(data & 1)) > break; > > - /* ...but clean it before doing the actual write */ > - vcpu->arch.time_offset = data & ~(PAGE_MASK | 1); > + gpa_offset = data & ~(PAGE_MASK | 1); > > /* Check that the address is 32-byte aligned. */ > - if (vcpu->arch.time_offset & > - (sizeof(struct pvclock_vcpu_time_info) - 1)) > + if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1)) > break; > > - vcpu->arch.time_page = > - gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT); > + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, > + &vcpu->arch.pv_time, data & ~1ULL)) > + vcpu->arch.pv_time_enabled = false; > + else > + vcpu->arch.pv_time_enabled = true; > > - if (is_error_page(vcpu->arch.time_page)) { > - kvm_release_page_clean(vcpu->arch.time_page); > - vcpu->arch.time_page = NULL; > - } > break; > } > case MSR_KVM_ASYNC_PF_EN: > @@ -2616,7 +2605,7 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu, > static int kvm_set_guest_paused(struct kvm_vcpu *vcpu) > { > struct pvclock_vcpu_time_info *src = &vcpu->arch.hv_clock; > - if (!vcpu->arch.time_page) > + if (!vcpu->arch.pv_time_enabled) > return -EINVAL; > src->flags |= PVCLOCK_GUEST_STOPPED; > mark_page_dirty(vcpu->kvm, vcpu->arch.time >> PAGE_SHIFT); > @@ -6216,6 +6205,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) > if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask, GFP_KERNEL)) > goto fail_free_mce_banks; > > + vcpu->arch.pv_time_enabled = false; > kvm_async_pf_hash_reset(vcpu); > kvm_pmu_init(vcpu); >
On Mon, Apr 22, 2013 at 04:54:49AM +0100, Ben Hutchings wrote: > On Thu, 2013-04-18 at 10:16 +0100, Luis Henriques wrote: > > 3.5.7.11 -stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Andy Honig <ahonig@google.com> > > > > commit 0b79459b482e85cb7426aa7da683a9f2c97aeae1 upstream. > > > > There is a potential use after free issue with the handling of > > MSR_KVM_SYSTEM_TIME. If the guest specifies a GPA in a movable or removable > > memory such as frame buffers then KVM might continue to write to that > > address even after it's removed via KVM_SET_USER_MEMORY_REGION. KVM pins > > the page in memory so it's unlikely to cause an issue, but if the user > > space component re-purposes the memory previously used for the guest, then > > the guest will be able to corrupt that memory. > > > > Tested: Tested against kvmclock unit test > > > > Signed-off-by: Andrew Honig <ahonig@google.com> > > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> > > [ luis: backported to 3.5: > > - Adjust context > > - Removed references to PVCLOCK_GUEST_STOPPED ] > > Signed-off-by: Luis Henriques <luis.henriques@canonical.com> > > This apparently needs to be followed by commit 8f964525a121 'KVM: Allow > cross page reads and writes from cached translations.', as some guests > don't follow the rules. Thanks Ben, I'll add it to the queue. Cheers, -- Luis > > Ben. > > > --- > > arch/x86/include/asm/kvm_host.h | 4 ++-- > > arch/x86/kvm/x86.c | 40 +++++++++++++++------------------------- > > 2 files changed, 17 insertions(+), 27 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index db7c1f2..9a50912 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -410,8 +410,8 @@ struct kvm_vcpu_arch { > > gpa_t time; > > struct pvclock_vcpu_time_info hv_clock; > > unsigned int hw_tsc_khz; > > - unsigned int time_offset; > > - struct page *time_page; > > + struct gfn_to_hva_cache pv_time; > > + bool pv_time_enabled; > > > > struct { > > u64 msr_val; > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index ad5cf4b..5b4ac78 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -1118,7 +1118,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > > { > > unsigned long flags; > > struct kvm_vcpu_arch *vcpu = &v->arch; > > - void *shared_kaddr; > > unsigned long this_tsc_khz; > > s64 kernel_ns, max_kernel_ns; > > u64 tsc_timestamp; > > @@ -1154,7 +1153,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > > > > local_irq_restore(flags); > > > > - if (!vcpu->time_page) > > + if (!vcpu->pv_time_enabled) > > return 0; > > > > /* > > @@ -1212,14 +1211,9 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > > */ > > vcpu->hv_clock.version += 2; > > > > - shared_kaddr = kmap_atomic(vcpu->time_page); > > - > > - memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock, > > - sizeof(vcpu->hv_clock)); > > - > > - kunmap_atomic(shared_kaddr); > > - > > - mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT); > > + kvm_write_guest_cached(v->kvm, &vcpu->pv_time, > > + &vcpu->hv_clock, > > + sizeof(vcpu->hv_clock)); > > return 0; > > } > > > > @@ -1508,10 +1502,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) > > > > static void kvmclock_reset(struct kvm_vcpu *vcpu) > > { > > - if (vcpu->arch.time_page) { > > - kvm_release_page_dirty(vcpu->arch.time_page); > > - vcpu->arch.time_page = NULL; > > - } > > + vcpu->arch.pv_time_enabled = false; > > } > > > > static void accumulate_steal_time(struct kvm_vcpu *vcpu) > > @@ -1606,6 +1597,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) > > break; > > case MSR_KVM_SYSTEM_TIME_NEW: > > case MSR_KVM_SYSTEM_TIME: { > > + u64 gpa_offset; > > kvmclock_reset(vcpu); > > > > vcpu->arch.time = data; > > @@ -1615,21 +1607,18 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) > > if (!(data & 1)) > > break; > > > > - /* ...but clean it before doing the actual write */ > > - vcpu->arch.time_offset = data & ~(PAGE_MASK | 1); > > + gpa_offset = data & ~(PAGE_MASK | 1); > > > > /* Check that the address is 32-byte aligned. */ > > - if (vcpu->arch.time_offset & > > - (sizeof(struct pvclock_vcpu_time_info) - 1)) > > + if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1)) > > break; > > > > - vcpu->arch.time_page = > > - gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT); > > + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, > > + &vcpu->arch.pv_time, data & ~1ULL)) > > + vcpu->arch.pv_time_enabled = false; > > + else > > + vcpu->arch.pv_time_enabled = true; > > > > - if (is_error_page(vcpu->arch.time_page)) { > > - kvm_release_page_clean(vcpu->arch.time_page); > > - vcpu->arch.time_page = NULL; > > - } > > break; > > } > > case MSR_KVM_ASYNC_PF_EN: > > @@ -2616,7 +2605,7 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu, > > static int kvm_set_guest_paused(struct kvm_vcpu *vcpu) > > { > > struct pvclock_vcpu_time_info *src = &vcpu->arch.hv_clock; > > - if (!vcpu->arch.time_page) > > + if (!vcpu->arch.pv_time_enabled) > > return -EINVAL; > > src->flags |= PVCLOCK_GUEST_STOPPED; > > mark_page_dirty(vcpu->kvm, vcpu->arch.time >> PAGE_SHIFT); > > @@ -6216,6 +6205,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) > > if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask, GFP_KERNEL)) > > goto fail_free_mce_banks; > > > > + vcpu->arch.pv_time_enabled = false; > > kvm_async_pf_hash_reset(vcpu); > > kvm_pmu_init(vcpu); > > > > -- > Ben Hutchings > Klipstein's 4th Law of Prototyping and Production: > A fail-safe circuit will destroy others.
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index db7c1f2..9a50912 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -410,8 +410,8 @@ struct kvm_vcpu_arch { gpa_t time; struct pvclock_vcpu_time_info hv_clock; unsigned int hw_tsc_khz; - unsigned int time_offset; - struct page *time_page; + struct gfn_to_hva_cache pv_time; + bool pv_time_enabled; struct { u64 msr_val; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ad5cf4b..5b4ac78 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1118,7 +1118,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) { unsigned long flags; struct kvm_vcpu_arch *vcpu = &v->arch; - void *shared_kaddr; unsigned long this_tsc_khz; s64 kernel_ns, max_kernel_ns; u64 tsc_timestamp; @@ -1154,7 +1153,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) local_irq_restore(flags); - if (!vcpu->time_page) + if (!vcpu->pv_time_enabled) return 0; /* @@ -1212,14 +1211,9 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) */ vcpu->hv_clock.version += 2; - shared_kaddr = kmap_atomic(vcpu->time_page); - - memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock, - sizeof(vcpu->hv_clock)); - - kunmap_atomic(shared_kaddr); - - mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT); + kvm_write_guest_cached(v->kvm, &vcpu->pv_time, + &vcpu->hv_clock, + sizeof(vcpu->hv_clock)); return 0; } @@ -1508,10 +1502,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) static void kvmclock_reset(struct kvm_vcpu *vcpu) { - if (vcpu->arch.time_page) { - kvm_release_page_dirty(vcpu->arch.time_page); - vcpu->arch.time_page = NULL; - } + vcpu->arch.pv_time_enabled = false; } static void accumulate_steal_time(struct kvm_vcpu *vcpu) @@ -1606,6 +1597,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) break; case MSR_KVM_SYSTEM_TIME_NEW: case MSR_KVM_SYSTEM_TIME: { + u64 gpa_offset; kvmclock_reset(vcpu); vcpu->arch.time = data; @@ -1615,21 +1607,18 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) if (!(data & 1)) break; - /* ...but clean it before doing the actual write */ - vcpu->arch.time_offset = data & ~(PAGE_MASK | 1); + gpa_offset = data & ~(PAGE_MASK | 1); /* Check that the address is 32-byte aligned. */ - if (vcpu->arch.time_offset & - (sizeof(struct pvclock_vcpu_time_info) - 1)) + if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1)) break; - vcpu->arch.time_page = - gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT); + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, + &vcpu->arch.pv_time, data & ~1ULL)) + vcpu->arch.pv_time_enabled = false; + else + vcpu->arch.pv_time_enabled = true; - if (is_error_page(vcpu->arch.time_page)) { - kvm_release_page_clean(vcpu->arch.time_page); - vcpu->arch.time_page = NULL; - } break; } case MSR_KVM_ASYNC_PF_EN: @@ -2616,7 +2605,7 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu, static int kvm_set_guest_paused(struct kvm_vcpu *vcpu) { struct pvclock_vcpu_time_info *src = &vcpu->arch.hv_clock; - if (!vcpu->arch.time_page) + if (!vcpu->arch.pv_time_enabled) return -EINVAL; src->flags |= PVCLOCK_GUEST_STOPPED; mark_page_dirty(vcpu->kvm, vcpu->arch.time >> PAGE_SHIFT); @@ -6216,6 +6205,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask, GFP_KERNEL)) goto fail_free_mce_banks; + vcpu->arch.pv_time_enabled = false; kvm_async_pf_hash_reset(vcpu); kvm_pmu_init(vcpu);