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linux-sg2042
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KVM: Disallow fork() and similar games when using a VM 

We don't want the meaning of guest userspace changing under our feet.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-11-21 16:41:05 +02:00
parent 76c35c6e99
commit 6d4e4c4fca
3 changed files with 11 additions and 0 deletions
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1
drivers/kvm/kvm.h
View File

@ -305,6 +305,7 @@ struct kvm_vm_stat {
struct kvm { struct kvm {
struct mutex lock; /* protects everything except vcpus */ struct mutex lock; /* protects everything except vcpus */
struct mm_struct *mm; /* userspace tied to this vm */
int naliases; int naliases;
struct kvm_mem_alias aliases[KVM_ALIAS_SLOTS]; struct kvm_mem_alias aliases[KVM_ALIAS_SLOTS];
int nmemslots; int nmemslots;

9
drivers/kvm/kvm_main.c
View File

@ -165,6 +165,8 @@ static struct kvm *kvm_create_vm(void)
if (IS_ERR(kvm)) if (IS_ERR(kvm))
goto out; goto out;
kvm->mm = current->mm;
atomic_inc(&kvm->mm->mm_count);
kvm_io_bus_init(&kvm->pio_bus); kvm_io_bus_init(&kvm->pio_bus);
mutex_init(&kvm->lock); mutex_init(&kvm->lock);
kvm_io_bus_init(&kvm->mmio_bus); kvm_io_bus_init(&kvm->mmio_bus);
@ -202,12 +204,15 @@ void kvm_free_physmem(struct kvm *kvm)
static void kvm_destroy_vm(struct kvm *kvm) static void kvm_destroy_vm(struct kvm *kvm)
{ {
struct mm_struct *mm = kvm->mm;
spin_lock(&kvm_lock); spin_lock(&kvm_lock);
list_del(&kvm->vm_list); list_del(&kvm->vm_list);
spin_unlock(&kvm_lock); spin_unlock(&kvm_lock);
kvm_io_bus_destroy(&kvm->pio_bus); kvm_io_bus_destroy(&kvm->pio_bus);
kvm_io_bus_destroy(&kvm->mmio_bus); kvm_io_bus_destroy(&kvm->mmio_bus);
kvm_arch_destroy_vm(kvm); kvm_arch_destroy_vm(kvm);
mmdrop(mm);
} }
static int kvm_vm_release(struct inode *inode, struct file *filp) static int kvm_vm_release(struct inode *inode, struct file *filp)
@ -818,6 +823,8 @@ static long kvm_vcpu_ioctl(struct file *filp,
void __user *argp = (void __user *)arg; void __user *argp = (void __user *)arg;
int r; int r;
if (vcpu->kvm->mm != current->mm)
return -EIO;
switch (ioctl) { switch (ioctl) {
case KVM_RUN: case KVM_RUN:
r = -EINVAL; r = -EINVAL;
@ -976,6 +983,8 @@ static long kvm_vm_ioctl(struct file *filp,
void __user *argp = (void __user *)arg; void __user *argp = (void __user *)arg;
int r; int r;
if (kvm->mm != current->mm)
return -EIO;
switch (ioctl) { switch (ioctl) {
case KVM_CREATE_VCPU: case KVM_CREATE_VCPU:
r = kvm_vm_ioctl_create_vcpu(kvm, arg); r = kvm_vm_ioctl_create_vcpu(kvm, arg);

1
kernel/fork.c
View File

@ -393,6 +393,7 @@ void fastcall __mmdrop(struct mm_struct *mm)
destroy_context(mm); destroy_context(mm);
free_mm(mm); free_mm(mm);
} }
EXPORT_SYMBOL_GPL(__mmdrop);
/* /*
* Decrement the use count and release all resources for an mm. * Decrement the use count and release all resources for an mm.