From 6d4e4c4fca5be806b888d606894d914847e82d78 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 21 Nov 2007 16:41:05 +0200 Subject: [PATCH] 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 --- drivers/kvm/kvm.h | 1 + drivers/kvm/kvm_main.c | 9 +++++++++ kernel/fork.c | 1 + 3 files changed, 11 insertions(+) diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h index 1fd8158ced..be18620bd6 100644 --- a/drivers/kvm/kvm.h +++ b/drivers/kvm/kvm.h @@ -305,6 +305,7 @@ struct kvm_vm_stat { struct kvm { struct mutex lock; /* protects everything except vcpus */ + struct mm_struct *mm; /* userspace tied to this vm */ int naliases; struct kvm_mem_alias aliases[KVM_ALIAS_SLOTS]; int nmemslots; diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c index aec6b67cfe..0efd759e58 100644 --- a/drivers/kvm/kvm_main.c +++ b/drivers/kvm/kvm_main.c @@ -165,6 +165,8 @@ static struct kvm *kvm_create_vm(void) if (IS_ERR(kvm)) goto out; + kvm->mm = current->mm; + atomic_inc(&kvm->mm->mm_count); kvm_io_bus_init(&kvm->pio_bus); mutex_init(&kvm->lock); 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) { + struct mm_struct *mm = kvm->mm; + spin_lock(&kvm_lock); list_del(&kvm->vm_list); spin_unlock(&kvm_lock); kvm_io_bus_destroy(&kvm->pio_bus); kvm_io_bus_destroy(&kvm->mmio_bus); kvm_arch_destroy_vm(kvm); + mmdrop(mm); } 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; int r; + if (vcpu->kvm->mm != current->mm) + return -EIO; switch (ioctl) { case KVM_RUN: r = -EINVAL; @@ -976,6 +983,8 @@ static long kvm_vm_ioctl(struct file *filp, void __user *argp = (void __user *)arg; int r; + if (kvm->mm != current->mm) + return -EIO; switch (ioctl) { case KVM_CREATE_VCPU: r = kvm_vm_ioctl_create_vcpu(kvm, arg); diff --git a/kernel/fork.c b/kernel/fork.c index 314f5101d2..05e0b6f436 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -393,6 +393,7 @@ void fastcall __mmdrop(struct mm_struct *mm) destroy_context(mm); free_mm(mm); } +EXPORT_SYMBOL_GPL(__mmdrop); /* * Decrement the use count and release all resources for an mm. -- 2.39.5