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Fix arm64 kvm priv escalation (rhbz 1635475 1635476)

This commit is contained in:
Justin M. Forbes 2018-10-03 07:55:07 -05:00
parent 772dbde034
commit d115630b52
2 changed files with 161 additions and 0 deletions
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155
arm64_kvm_security.patch Normal file
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@ -0,0 +1,155 @@
From d26c25a9d19b5976b319af528886f89cf455692d Mon Sep 17 00:00:00 2001
From: Dave Martin <Dave.Martin@arm.com>
Date: Thu, 27 Sep 2018 16:53:21 +0100
Subject: arm64: KVM: Tighten guest core register access from userspace
From: Dave Martin <Dave.Martin@arm.com>
commit d26c25a9d19b5976b319af528886f89cf455692d upstream.
We currently allow userspace to access the core register file
in about any possible way, including straddling multiple
registers and doing unaligned accesses.
This is not the expected use of the ABI, and nobody is actually
using it that way. Let's tighten it by explicitly checking
the size and alignment for each field of the register file.
Cc: <stable@vger.kernel.org>
Fixes: 2f4a07c5f9fe ("arm64: KVM: guest one-reg interface")
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
[maz: rewrote Dave's initial patch to be more easily backported]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kvm/guest.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -57,6 +57,45 @@ static u64 core_reg_offset_from_id(u64 i
return id & ~(KVM_REG_ARCH_MASK | KVM_REG_SIZE_MASK | KVM_REG_ARM_CORE);
}
+static int validate_core_offset(const struct kvm_one_reg *reg)
+{
+ u64 off = core_reg_offset_from_id(reg->id);
+ int size;
+
+ switch (off) {
+ case KVM_REG_ARM_CORE_REG(regs.regs[0]) ...
+ KVM_REG_ARM_CORE_REG(regs.regs[30]):
+ case KVM_REG_ARM_CORE_REG(regs.sp):
+ case KVM_REG_ARM_CORE_REG(regs.pc):
+ case KVM_REG_ARM_CORE_REG(regs.pstate):
+ case KVM_REG_ARM_CORE_REG(sp_el1):
+ case KVM_REG_ARM_CORE_REG(elr_el1):
+ case KVM_REG_ARM_CORE_REG(spsr[0]) ...
+ KVM_REG_ARM_CORE_REG(spsr[KVM_NR_SPSR - 1]):
+ size = sizeof(__u64);
+ break;
+
+ case KVM_REG_ARM_CORE_REG(fp_regs.vregs[0]) ...
+ KVM_REG_ARM_CORE_REG(fp_regs.vregs[31]):
+ size = sizeof(__uint128_t);
+ break;
+
+ case KVM_REG_ARM_CORE_REG(fp_regs.fpsr):
+ case KVM_REG_ARM_CORE_REG(fp_regs.fpcr):
+ size = sizeof(__u32);
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ if (KVM_REG_SIZE(reg->id) == size &&
+ IS_ALIGNED(off, size / sizeof(__u32)))
+ return 0;
+
+ return -EINVAL;
+}
+
static int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
/*
@@ -76,6 +115,9 @@ static int get_core_reg(struct kvm_vcpu
(off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)
return -ENOENT;
+ if (validate_core_offset(reg))
+ return -EINVAL;
+
if (copy_to_user(uaddr, ((u32 *)regs) + off, KVM_REG_SIZE(reg->id)))
return -EFAULT;
@@ -98,6 +140,9 @@ static int set_core_reg(struct kvm_vcpu
(off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)
return -ENOENT;
+ if (validate_core_offset(reg))
+ return -EINVAL;
+
if (KVM_REG_SIZE(reg->id) > sizeof(tmp))
return -EINVAL;
From 2a3f93459d689d990b3ecfbe782fec89b97d3279 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@arm.com>
Date: Thu, 27 Sep 2018 16:53:22 +0100
Subject: arm64: KVM: Sanitize PSTATE.M when being set from userspace
From: Marc Zyngier <marc.zyngier@arm.com>
commit 2a3f93459d689d990b3ecfbe782fec89b97d3279 upstream.
Not all execution modes are valid for a guest, and some of them
depend on what the HW actually supports. Let's verify that what
userspace provides is compatible with both the VM settings and
the HW capabilities.
Cc: <stable@vger.kernel.org>
Fixes: 0d854a60b1d7 ("arm64: KVM: enable initialization of a 32bit vcpu")
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kvm/guest.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -152,17 +152,25 @@ static int set_core_reg(struct kvm_vcpu
}
if (off == KVM_REG_ARM_CORE_REG(regs.pstate)) {
- u32 mode = (*(u32 *)valp) & COMPAT_PSR_MODE_MASK;
+ u64 mode = (*(u64 *)valp) & COMPAT_PSR_MODE_MASK;
switch (mode) {
case COMPAT_PSR_MODE_USR:
+ if (!system_supports_32bit_el0())
+ return -EINVAL;
+ break;
case COMPAT_PSR_MODE_FIQ:
case COMPAT_PSR_MODE_IRQ:
case COMPAT_PSR_MODE_SVC:
case COMPAT_PSR_MODE_ABT:
case COMPAT_PSR_MODE_UND:
+ if (!vcpu_el1_is_32bit(vcpu))
+ return -EINVAL;
+ break;
case PSR_MODE_EL0t:
case PSR_MODE_EL1t:
case PSR_MODE_EL1h:
+ if (vcpu_el1_is_32bit(vcpu))
+ return -EINVAL;
break;
default:
err = -EINVAL;

6
kernel.spec
View File

@ -674,6 +674,9 @@ Patch536: powerpc-ipv6.patch
# rhbz 1634250
Patch537: HID-intel-ish-hid-Enable-Sunrise-Point-H-ish-driver.patch
# rhbz 1635475 1635476
Patch538: arm64_kvm_security.patch
# END OF PATCH DEFINITIONS
%endif
@ -1933,6 +1936,9 @@ fi
#
#
%changelog
* Wed Oct 03 2018 Justin M. Forbes <jforbes@fedoraproject.org>
- Fix arm64 kvm priv escalation (rhbz 1635475 1635476)
* Mon Oct 01 2018 Laura Abbott <labbott@redhat.com>
- Disable CONFIG_CRYPTO_DEV_SP_PSP (rhbz 1608242)