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KVM: arm64: vgic-v3: Consolidate userspace access for MMIO registers 

For userspace accesses to GICv3 MMIO registers (and related data),
vgic_v3_{get,set}_attr are littered with {get,put}_user() calls,
making it hard to audit and reason about.

Consolidate all userspace accesses in vgic_v3_attr_regs_access(),
making the code far simpler to audit.

Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2022-07-05 10:26:07 +01:00
parent 38cf0bb762
commit e1246f3f2d
1 changed files with 37 additions and 66 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

103
arch/arm64/kvm/vgic/vgic-kvm-device.c
View File

@ -512,18 +512,18 @@ int vgic_v3_parse_attr(struct kvm_device *dev, struct kvm_device_attr *attr,
*
* @dev: kvm device handle
* @attr: kvm device attribute
* @reg: address the value is read or written, NULL for sysregs
* @is_write: true if userspace is writing a register
*/
static int vgic_v3_attr_regs_access(struct kvm_device *dev,
struct kvm_device_attr *attr,
u64 *reg, bool is_write)
bool is_write)
{
struct vgic_reg_attr reg_attr;
gpa_t addr;
struct kvm_vcpu *vcpu;
bool uaccess;
u32 val;
int ret;
u32 tmp32;
ret = vgic_v3_parse_attr(dev, attr, &reg_attr);
if (ret)
@ -532,6 +532,21 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
vcpu = reg_attr.vcpu;
addr = reg_attr.addr;
switch (attr->group) {
case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
/* Sysregs uaccess is performed by the sysreg handling code */
uaccess = false;
break;
default:
uaccess = true;
}
if (uaccess && is_write) {
u32 __user *uaddr = (u32 __user *)(unsigned long)attr->addr;
if (get_user(val, uaddr))
return -EFAULT;
}
mutex_lock(&dev->kvm->lock);
if (unlikely(!vgic_initialized(dev->kvm))) {
@ -546,20 +561,10 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
switch (attr->group) {
case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
if (is_write)
tmp32 = *reg;
ret = vgic_v3_dist_uaccess(vcpu, is_write, addr, &tmp32);
if (!is_write)
*reg = tmp32;
ret = vgic_v3_dist_uaccess(vcpu, is_write, addr, &val);
break;
case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:
if (is_write)
tmp32 = *reg;
ret = vgic_v3_redist_uaccess(vcpu, is_write, addr, &tmp32);
if (!is_write)
*reg = tmp32;
ret = vgic_v3_redist_uaccess(vcpu, is_write, addr, &val);
break;
case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
ret = vgic_v3_cpu_sysregs_uaccess(vcpu, attr, is_write);
@ -570,14 +575,10 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
info = (attr->attr & KVM_DEV_ARM_VGIC_LINE_LEVEL_INFO_MASK) >>
KVM_DEV_ARM_VGIC_LINE_LEVEL_INFO_SHIFT;
if (info == VGIC_LEVEL_INFO_LINE_LEVEL) {
if (is_write)
tmp32 = *reg;
intid = attr->attr &
KVM_DEV_ARM_VGIC_LINE_LEVEL_INTID_MASK;
ret = vgic_v3_line_level_info_uaccess(vcpu, is_write,
intid, &tmp32);
if (!is_write)
*reg = tmp32;
intid, &val);
} else {
ret = -EINVAL;
}
@ -591,6 +592,12 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
unlock_all_vcpus(dev->kvm);
out:
mutex_unlock(&dev->kvm->lock);
if (!ret && uaccess && !is_write) {
u32 __user *uaddr = (u32 __user *)(unsigned long)attr->addr;
ret = put_user(val, uaddr);
}
return ret;
}
@ -605,30 +612,12 @@ static int vgic_v3_set_attr(struct kvm_device *dev,
switch (attr->group) {
case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS: {
u32 __user *uaddr = (u32 __user *)(long)attr->addr;
u32 tmp32;
u64 reg;
if (get_user(tmp32, uaddr))
return -EFAULT;
reg = tmp32;
return vgic_v3_attr_regs_access(dev, attr, &reg, true);
}
case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:
return vgic_v3_attr_regs_access(dev, attr, true);
case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
return vgic_v3_attr_regs_access(dev, attr, NULL, true);
case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO: {
u32 __user *uaddr = (u32 __user *)(long)attr->addr;
u64 reg;
u32 tmp32;
if (get_user(tmp32, uaddr))
return -EFAULT;
reg = tmp32;
return vgic_v3_attr_regs_access(dev, attr, &reg, true);
}
return vgic_v3_attr_regs_access(dev, attr, true);
case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO:
return vgic_v3_attr_regs_access(dev, attr, true);
case KVM_DEV_ARM_VGIC_GRP_CTRL: {
int ret;
@ -662,30 +651,12 @@ static int vgic_v3_get_attr(struct kvm_device *dev,
switch (attr->group) {
case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS: {
u32 __user *uaddr = (u32 __user *)(long)attr->addr;
u64 reg;
u32 tmp32;
ret = vgic_v3_attr_regs_access(dev, attr, &reg, false);
if (ret)
return ret;
tmp32 = reg;
return put_user(tmp32, uaddr);
}
case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:
return vgic_v3_attr_regs_access(dev, attr, false);
case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
return vgic_v3_attr_regs_access(dev, attr, NULL, false);
case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO: {
u32 __user *uaddr = (u32 __user *)(long)attr->addr;
u64 reg;
u32 tmp32;
ret = vgic_v3_attr_regs_access(dev, attr, &reg, false);
if (ret)
return ret;
tmp32 = reg;
return put_user(tmp32, uaddr);
}
return vgic_v3_attr_regs_access(dev, attr, false);
case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO:
return vgic_v3_attr_regs_access(dev, attr, false);
}
return -ENXIO;
}