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vhost: return bool from *_access_ok() functions
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Currently vhost *_access_ok() functions return int.  This is error-prone
because there are two popular conventions:

1. 0 means failure, 1 means success
2. -errno means failure, 0 means success

Although vhost mostly uses #1, it does not do so consistently.
umem_access_ok() uses #2.

This patch changes the return type from int to bool so that false means
failure and true means success.  This eliminates a potential source of
errors.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@stefanhaRH @davem330
stefanhaRH authored and davem330 committed Apr 11, 2018
1 parent d14d2b7 commit ddd3d40
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Showing 2 changed files with 35 additions and 35 deletions.
66 changes: 33 additions & 33 deletions drivers/vhost/vhost.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -641,14 +641,14 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
}
EXPORT_SYMBOL_GPL(vhost_dev_cleanup);

static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
{
u64 a = addr / VHOST_PAGE_SIZE / 8;

/* Make sure 64 bit math will not overflow. */
if (a > ULONG_MAX - (unsigned long)log_base ||
a + (unsigned long)log_base > ULONG_MAX)
return 0;
return false;

return access_ok(VERIFY_WRITE, log_base + a,
(sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
Expand All @@ -661,30 +661,30 @@ static bool vhost_overflow(u64 uaddr, u64 size)
}

/* Caller should have vq mutex and device mutex. */
static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
int log_all)
static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
int log_all)
{
struct vhost_umem_node *node;

if (!umem)
return 0;
return false;

list_for_each_entry(node, &umem->umem_list, link) {
unsigned long a = node->userspace_addr;

if (vhost_overflow(node->userspace_addr, node->size))
return 0;
return false;


if (!access_ok(VERIFY_WRITE, (void __user *)a,
node->size))
return 0;
return false;
else if (log_all && !log_access_ok(log_base,
node->start,
node->size))
return 0;
return false;
}
return 1;
return true;
}

static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
Expand All @@ -701,13 +701,13 @@ static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,

/* Can we switch to this memory table? */
/* Caller should have device mutex but not vq mutex */
static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
int log_all)
static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
int log_all)
{
int i;

for (i = 0; i < d->nvqs; ++i) {
int ok;
bool ok;
bool log;

mutex_lock(&d->vqs[i]->mutex);
Expand All @@ -717,12 +717,12 @@ static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
ok = vq_memory_access_ok(d->vqs[i]->log_base,
umem, log);
else
ok = 1;
ok = true;
mutex_unlock(&d->vqs[i]->mutex);
if (!ok)
return 0;
return false;
}
return 1;
return true;
}

static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
Expand Down Expand Up @@ -959,21 +959,21 @@ static void vhost_iotlb_notify_vq(struct vhost_dev *d,
spin_unlock(&d->iotlb_lock);
}

static int umem_access_ok(u64 uaddr, u64 size, int access)
static bool umem_access_ok(u64 uaddr, u64 size, int access)
{
unsigned long a = uaddr;

/* Make sure 64 bit math will not overflow. */
if (vhost_overflow(uaddr, size))
return -EFAULT;
return false;

if ((access & VHOST_ACCESS_RO) &&
!access_ok(VERIFY_READ, (void __user *)a, size))
return -EFAULT;
return false;
if ((access & VHOST_ACCESS_WO) &&
!access_ok(VERIFY_WRITE, (void __user *)a, size))
return -EFAULT;
return 0;
return false;
return true;
}

static int vhost_process_iotlb_msg(struct vhost_dev *dev,
Expand All @@ -988,7 +988,7 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
ret = -EFAULT;
break;
}
if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
ret = -EFAULT;
break;
}
Expand Down Expand Up @@ -1135,10 +1135,10 @@ static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
return 0;
}

static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
struct vring_desc __user *desc,
struct vring_avail __user *avail,
struct vring_used __user *used)
static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
struct vring_desc __user *desc,
struct vring_avail __user *avail,
struct vring_used __user *used)

{
size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
Expand All @@ -1161,8 +1161,8 @@ static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
vq->meta_iotlb[type] = node;
}

static int iotlb_access_ok(struct vhost_virtqueue *vq,
int access, u64 addr, u64 len, int type)
static bool iotlb_access_ok(struct vhost_virtqueue *vq,
int access, u64 addr, u64 len, int type)
{
const struct vhost_umem_node *node;
struct vhost_umem *umem = vq->iotlb;
Expand Down Expand Up @@ -1220,16 +1220,16 @@ EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);

/* Can we log writes? */
/* Caller should have device mutex but not vq mutex */
int vhost_log_access_ok(struct vhost_dev *dev)
bool vhost_log_access_ok(struct vhost_dev *dev)
{
return memory_access_ok(dev, dev->umem, 1);
}
EXPORT_SYMBOL_GPL(vhost_log_access_ok);

/* Verify access for write logging. */
/* Caller should have vq mutex and device mutex */
static int vq_log_access_ok(struct vhost_virtqueue *vq,
void __user *log_base)
static bool vq_log_access_ok(struct vhost_virtqueue *vq,
void __user *log_base)
{
size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;

Expand All @@ -1242,14 +1242,14 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq,

/* Can we start vq? */
/* Caller should have vq mutex and device mutex */
int vhost_vq_access_ok(struct vhost_virtqueue *vq)
bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
{
if (!vq_log_access_ok(vq, vq->log_base))
return 0;
return false;

/* Access validation occurs at prefetch time with IOTLB */
if (vq->iotlb)
return 1;
return true;

return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
}
Expand Down
4 changes: 2 additions & 2 deletions drivers/vhost/vhost.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -178,8 +178,8 @@ void vhost_dev_cleanup(struct vhost_dev *);
void vhost_dev_stop(struct vhost_dev *);
long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp);
int vhost_vq_access_ok(struct vhost_virtqueue *vq);
int vhost_log_access_ok(struct vhost_dev *);
bool vhost_vq_access_ok(struct vhost_virtqueue *vq);
bool vhost_log_access_ok(struct vhost_dev *);

int vhost_get_vq_desc(struct vhost_virtqueue *,
struct iovec iov[], unsigned int iov_count,
Expand Down

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