[PATCH v4 3/5] media: Refactor copying IOCTL arguments from and to user space

Sakari Ailus
2016-08-11T20:30:38Z

Refactor copying the IOCTL argument structs from the user space and back,
in order to reduce code copied around and make the implementation more
robust.

As a result, the copying is done while not holding the graph mutex.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
---
drivers/media/media-device.c | 190 ++++++++++++++++++++-----------------------
1 file changed, 90 insertions(+), 100 deletions(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index cc6c566..d1b47a4 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -59,27 +59,24 @@ static int media_device_close(struct file *filp)
}

static int media_device_get_info(struct media_device *dev,
- struct media_device_info __user *__info)
+ struct media_device_info *info)
{
- struct media_device_info info;
-
- memset(&info, 0, sizeof(info));
+ memset(info, 0, sizeof(*info));

if (dev->driver_name[0])
- strlcpy(info.driver, dev->driver_name, sizeof(info.driver));
+ strlcpy(info->driver, dev->driver_name, sizeof(info->driver));
else
- strlcpy(info.driver, dev->dev->driver->name, sizeof(info.driver));
+ strlcpy(info->driver, dev->dev->driver->name,
+ sizeof(info->driver));

- strlcpy(info.model, dev->model, sizeof(info.model));
- strlcpy(info.serial, dev->serial, sizeof(info.serial));
- strlcpy(info.bus_info, dev->bus_info, sizeof(info.bus_info));
+ strlcpy(info->model, dev->model, sizeof(info->model));
+ strlcpy(info->serial, dev->serial, sizeof(info->serial));
+ strlcpy(info->bus_info, dev->bus_info, sizeof(info->bus_info));

- info.media_version = MEDIA_API_VERSION;
- info.hw_revision = dev->hw_revision;
- info.driver_version = dev->driver_version;
+ info->media_version = MEDIA_API_VERSION;
+ info->hw_revision = dev->hw_revision;
+ info->driver_version = dev->driver_version;

- if (copy_to_user(__info, &info, sizeof(*__info)))
- return -EFAULT;
return 0;
}

@@ -101,29 +98,25 @@ static struct media_entity *find_entity(struct media_device *mdev, u32 id)
}

static long media_device_enum_entities(struct media_device *mdev,
- struct media_entity_desc __user *uent)
+ struct media_entity_desc *entd)
{
struct media_entity *ent;
- struct media_entity_desc u_ent;
-
- memset(&u_ent, 0, sizeof(u_ent));
- if (copy_from_user(&u_ent.id, &uent->id, sizeof(u_ent.id)))
- return -EFAULT;
-
- ent = find_entity(mdev, u_ent.id);

+ ent = find_entity(mdev, entd->id);
if (ent == NULL)
return -EINVAL;

- u_ent.id = media_entity_id(ent);
+ memset(entd, 0, sizeof(*entd));
+
+ entd->id = media_entity_id(ent);
if (ent->name)
- strlcpy(u_ent.name, ent->name, sizeof(u_ent.name));
- u_ent.type = ent->function;
- u_ent.revision = 0; /* Unused */
- u_ent.flags = ent->flags;
- u_ent.group_id = 0; /* Unused */
- u_ent.pads = ent->num_pads;
- u_ent.links = ent->num_links - ent->num_backlinks;
+ strlcpy(entd->name, ent->name, sizeof(entd->name));
+ entd->type = ent->function;
+ entd->revision = 0; /* Unused */
+ entd->flags = ent->flags;
+ entd->group_id = 0; /* Unused */
+ entd->pads = ent->num_pads;
+ entd->links = ent->num_links - ent->num_backlinks;

/*
* Workaround for a bug at media-ctl <= v1.10 that makes it to
@@ -139,14 +132,13 @@ static long media_device_enum_entities(struct media_device *mdev,
if (ent->function < MEDIA_ENT_F_OLD_BASE ||
ent->function > MEDIA_ENT_T_DEVNODE_UNKNOWN) {
if (is_media_entity_v4l2_subdev(ent))
- u_ent.type = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
+ entd->type = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
else if (ent->function != MEDIA_ENT_F_IO_V4L)
- u_ent.type = MEDIA_ENT_T_DEVNODE_UNKNOWN;
+ entd->type = MEDIA_ENT_T_DEVNODE_UNKNOWN;
}

- memcpy(&u_ent.raw, &ent->info, sizeof(ent->info));
- if (copy_to_user(uent, &u_ent, sizeof(u_ent)))
- return -EFAULT;
+ memcpy(&entd->raw, &ent->info, sizeof(ent->info));
+
return 0;
}

@@ -158,8 +150,8 @@ static void media_device_kpad_to_upad(const struct media_pad *kpad,
upad->flags = kpad->flags;
}

-static long __media_device_enum_links(struct media_device *mdev,
- struct media_links_enum *links)
+static long media_device_enum_links(struct media_device *mdev,
+ struct media_links_enum *links)
{
struct media_entity *entity;

@@ -206,64 +198,35 @@ static long __media_device_enum_links(struct media_device *mdev,
return 0;
}

-static long media_device_enum_links(struct media_device *mdev,
- struct media_links_enum __user *ulinks)
-{
- struct media_links_enum links;
- int rval;
-
- if (copy_from_user(&links, ulinks, sizeof(links)))
- return -EFAULT;
-
- rval = __media_device_enum_links(mdev, &links);
- if (rval < 0)
- return rval;
-
- if (copy_to_user(ulinks, &links, sizeof(*ulinks)))
- return -EFAULT;
-
- return 0;
-}
-
static long media_device_setup_link(struct media_device *mdev,
- struct media_link_desc __user *_ulink)
+ struct media_link_desc *linkd)
{
struct media_link *link = NULL;
- struct media_link_desc ulink;
struct media_entity *source;
struct media_entity *sink;
- int ret;
-
- if (copy_from_user(&ulink, _ulink, sizeof(ulink)))
- return -EFAULT;

/* Find the source and sink entities and link.
*/
- source = find_entity(mdev, ulink.source.entity);
- sink = find_entity(mdev, ulink.sink.entity);
+ source = find_entity(mdev, linkd->source.entity);
+ sink = find_entity(mdev, linkd->sink.entity);

if (source == NULL || sink == NULL)
return -EINVAL;

- if (ulink.source.index >= source->num_pads ||
- ulink.sink.index >= sink->num_pads)
+ if (linkd->source.index >= source->num_pads ||
+ linkd->sink.index >= sink->num_pads)
return -EINVAL;

- link = media_entity_find_link(&source->pads[ulink.source.index],
- &sink->pads[ulink.sink.index]);
+ link = media_entity_find_link(&source->pads[linkd->source.index],
+ &sink->pads[linkd->sink.index]);
if (link == NULL)
return -EINVAL;

/* Setup the link on both entities. */
- ret = __media_entity_setup_link(link, ulink.flags);
-
- if (copy_to_user(_ulink, &ulink, sizeof(ulink)))
- return -EFAULT;
-
- return ret;
+ return __media_entity_setup_link(link, linkd->flags);
}

-static long __media_device_get_topology(struct media_device *mdev,
+static long media_device_get_topology(struct media_device *mdev,
struct media_v2_topology *topo)
{
struct media_entity *entity;
@@ -400,35 +363,41 @@ static long __media_device_get_topology(struct media_device *mdev,
return ret;
}

-static long media_device_get_topology(struct media_device *mdev,
- struct media_v2_topology __user *utopo)
+static long copy_arg_from_user(void *karg, void __user *uarg, unsigned int cmd)
{
- struct media_v2_topology ktopo;
- int ret;
-
- if (copy_from_user(&ktopo, utopo, sizeof(ktopo)))
+ /* All media IOCTLs are _IOWR() */
+ if (copy_from_user(karg, uarg, _IOC_SIZE(cmd)))
return -EFAULT;

- ret = __media_device_get_topology(mdev, &ktopo);
- if (ret < 0)
- return ret;
+ return 0;
+}

- if (copy_to_user(utopo, &ktopo, sizeof(*utopo)))
+static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
+{
+ /* All media IOCTLs are _IOWR() */
+ if (copy_to_user(uarg, karg, _IOC_SIZE(cmd)))
return -EFAULT;

return 0;
}

-#define MEDIA_IOC(__cmd, func) \
- [_IOC_NR(MEDIA_IOC_##__cmd)] = { \
- .cmd = MEDIA_IOC_##__cmd, \
- .fn = (long (*)(struct media_device *, void __user *))func, \
+#define MEDIA_IOC_ARG(__cmd, func, from_user, to_user) \
+ [_IOC_NR(MEDIA_IOC_##__cmd)] = { \
+ .cmd = MEDIA_IOC_##__cmd, \
+ .fn = (long (*)(struct media_device *, void *))func, \
+ .arg_from_user = from_user, \
+ .arg_to_user = to_user, \
}

+#define MEDIA_IOC(__cmd, func) \
+ MEDIA_IOC_ARG(__cmd, func, copy_arg_from_user, copy_arg_to_user)
+
/* the table is indexed by _IOC_NR(cmd) */
struct media_ioctl_info {
unsigned int cmd;
- long (*fn)(struct media_device *dev, void __user *arg);
+ long (*fn)(struct media_device *dev, void *arg);
+ long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
+ long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
};

static const struct media_ioctl_info ioctl_info[] = {
@@ -453,6 +422,7 @@ static long __media_device_ioctl(
struct media_devnode *devnode = media_devnode_data(filp);
struct media_device *dev = devnode->media_dev;
const struct media_ioctl_info *info;
+ char __karg[256], *karg = __karg;
long ret;

ret = is_valid_ioctl(info_array, cmd);
@@ -461,10 +431,29 @@ static long __media_device_ioctl(

info = &info_array[_IOC_NR(cmd)];

+ if (_IOC_SIZE(info->cmd) > sizeof(__karg)) {
+ karg = kmalloc(_IOC_SIZE(info->cmd), GFP_KERNEL);
+ if (!karg)
+ return -ENOMEM;
+ }
+
+ if (info->arg_from_user) {
+ ret = info->arg_from_user(karg, arg, cmd);
+ if (ret)
+ goto out_free;
+ }
+
mutex_lock(&dev->graph_mutex);
- ret = info->fn(dev, arg);
+ ret = info->fn(dev, karg);
mutex_unlock(&dev->graph_mutex);

+ if (!ret && info->arg_to_user)
+ ret = info->arg_to_user(arg, karg, cmd);
+
+out_free:
+ if (karg != __karg)
+ kfree(karg);
+
return ret;
}

@@ -484,23 +473,24 @@ struct media_links_enum32 {
__u32 reserved[4];
};

-static long media_device_enum_links32(struct media_device *mdev,
- struct media_links_enum32 __user *ulinks)
+static long from_user_enum_links32(void *karg, void __user *uarg,
+ unsigned int cmd)
{
- struct media_links_enum links;
+ struct media_links_enum *links = karg;
+ struct media_links_enum32 __user *ulinks = uarg;
compat_uptr_t pads_ptr, links_ptr;

- memset(&links, 0, sizeof(links));
+ memset(links, 0, sizeof(*links));

- if (get_user(links.entity, &ulinks->entity)
+ if (get_user(links->entity, &ulinks->entity)
|| get_user(pads_ptr, &ulinks->pads)
|| get_user(links_ptr, &ulinks->links))
return -EFAULT;

- links.pads = compat_ptr(pads_ptr);
- links.links = compat_ptr(links_ptr);
+ links->pads = compat_ptr(pads_ptr);
+ links->links = compat_ptr(links_ptr);

- return __media_device_enum_links(mdev, &links);
+ return 0;
}

#define MEDIA_IOC_ENUM_LINKS32 _IOWR('|', 0x02, struct media_links_enum32)
@@ -508,7 +498,7 @@ static long media_device_enum_links32(struct media_device *mdev,
static const struct media_ioctl_info compat_ioctl_info[] = {
MEDIA_IOC(DEVICE_INFO, media_device_get_info),
MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
- MEDIA_IOC(ENUM_LINKS32, media_device_enum_links32),
+ MEDIA_IOC_ARG(ENUM_LINKS32, media_device_enum_links, from_user_enum_links32, NULL),
MEDIA_IOC(SETUP_LINK, media_device_setup_link),
MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
};
--
2.7.4