[PATCH v2 3/8] media: v4l2: move v4l2_ext_controls conversion

Arnd Bergmann
2020-10-30T16:55:50Z

The v4l2_ext_controls ioctl handlers use an indirect pointer to an
incompatible data structure, making the conversion particularly tricky.

Moving the compat implementation to use the new
v4l2_compat_get_user()/v4l2_compat_put_user() helpers makes it
noticeably simpler.

In v4l2_compat_get_array_args()/v4l2_compat_put_array_args(),
the 'file' argument needs to get passed to determine the
exact format, which is a bit unfortunate, as no other conversion
needs these.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 236 +++++++-----------
1 file changed, 90 insertions(+), 146 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
index a76f6ac5b1eb..fa94cdec7df5 100644
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -1124,142 +1124,44 @@ static inline bool ctrl_is_pointer(struct file *file, u32 id)
(qec.flags & V4L2_CTRL_FLAG_HAS_PAYLOAD);
}

-static int bufsize_v4l2_ext_controls(struct v4l2_ext_controls32 __user *p32,
- u32 *size)
-{
- u32 count;
-
- if (!access_ok(p32, sizeof(*p32)) ||
- get_user(count, &p32->count))
- return -EFAULT;
- if (count > V4L2_CID_MAX_CTRLS)
- return -EINVAL;
- *size = count * sizeof(struct v4l2_ext_control);
- return 0;
-}
-
-static int get_v4l2_ext_controls32(struct file *file,
- struct v4l2_ext_controls __user *p64,
- struct v4l2_ext_controls32 __user *p32,
- void __user *aux_buf, u32 aux_space)
+static int get_v4l2_ext_controls32(struct v4l2_ext_controls *p64,
+ struct v4l2_ext_controls32 __user *p32)
{
- struct v4l2_ext_control32 __user *ucontrols;
- struct v4l2_ext_control __user *kcontrols;
- u32 count;
- u32 n;
- compat_caddr_t p;
-
- if (!access_ok(p32, sizeof(*p32)) ||
- assign_in_user(&p64->which, &p32->which) ||
- get_user(count, &p32->count) ||
- put_user(count, &p64->count) ||
- assign_in_user(&p64->error_idx, &p32->error_idx) ||
- assign_in_user(&p64->request_fd, &p32->request_fd) ||
- copy_in_user(p64->reserved, p32->reserved, sizeof(p64->reserved)))
- return -EFAULT;
+ struct v4l2_ext_controls32 ec32;

- if (count == 0)
- return put_user(NULL, &p64->controls);
- if (count > V4L2_CID_MAX_CTRLS)
- return -EINVAL;
- if (get_user(p, &p32->controls))
- return -EFAULT;
- ucontrols = compat_ptr(p);
- if (!access_ok(ucontrols, count * sizeof(*ucontrols)))
- return -EFAULT;
- if (aux_space < count * sizeof(*kcontrols))
+ if (copy_from_user(&ec32, p32, sizeof(ec32)))
return -EFAULT;
- kcontrols = aux_buf;
- if (put_user_force(kcontrols, &p64->controls))
- return -EFAULT;
-
- for (n = 0; n < count; n++) {
- u32 id;
-
- if (copy_in_user(kcontrols, ucontrols, sizeof(*ucontrols)))
- return -EFAULT;
-
- if (get_user(id, &kcontrols->id))
- return -EFAULT;

- if (ctrl_is_pointer(file, id)) {
- void __user *s;
+ *p64 = (struct v4l2_ext_controls) {
+ .which = ec32.which,
+ .count = ec32.count,
+ .error_idx = ec32.error_idx,
+ .request_fd = ec32.request_fd,
+ .reserved[0] = ec32.reserved[0],
+ .controls = (void __force *)compat_ptr(ec32.controls),
+ };

- if (get_user(p, &ucontrols->string))
- return -EFAULT;
- s = compat_ptr(p);
- if (put_user(s, &kcontrols->string))
- return -EFAULT;
- }
- ucontrols++;
- kcontrols++;
- }
return 0;
}

-static int put_v4l2_ext_controls32(struct file *file,
- struct v4l2_ext_controls __user *p64,
+static int put_v4l2_ext_controls32(struct v4l2_ext_controls *p64,
struct v4l2_ext_controls32 __user *p32)
{
- struct v4l2_ext_control32 __user *ucontrols;
- struct v4l2_ext_control *kcontrols;
- u32 count;
- u32 n;
- compat_caddr_t p;
-
- /*
- * We need to define kcontrols without __user, even though it does
- * point to data in userspace here. The reason is that v4l2-ioctl.c
- * copies it from userspace to kernelspace, so its definition in
- * videodev2.h doesn't have a __user markup. Defining kcontrols
- * with __user causes smatch warnings, so instead declare it
- * without __user and cast it as a userspace pointer where needed.
- */
- if (!access_ok(p32, sizeof(*p32)) ||
- assign_in_user(&p32->which, &p64->which) ||
- get_user(count, &p64->count) ||
- put_user(count, &p32->count) ||
- assign_in_user(&p32->error_idx, &p64->error_idx) ||
- assign_in_user(&p32->request_fd, &p64->request_fd) ||
- copy_in_user(p32->reserved, p64->reserved, sizeof(p32->reserved)) ||
- get_user(kcontrols, &p64->controls))
- return -EFAULT;
+ struct v4l2_ext_controls32 ec32;
+
+ memset(&ec32, 0, sizeof(ec32));
+ ec32 = (struct v4l2_ext_controls32) {
+ .which = p64->which,
+ .count = p64->count,
+ .error_idx = p64->error_idx,
+ .request_fd = p64->request_fd,
+ .reserved[0] = p64->reserved[0],
+ .controls = (uintptr_t)p64->controls,
+ };

- if (!count || count > (U32_MAX/sizeof(*ucontrols)))
- return 0;
- if (get_user(p, &p32->controls))
- return -EFAULT;
- ucontrols = compat_ptr(p);
- if (!access_ok(ucontrols, count * sizeof(*ucontrols)))
+ if (copy_to_user(p32, &ec32, sizeof(ec32)))
return -EFAULT;

- for (n = 0; n < count; n++) {
- unsigned int size = sizeof(*ucontrols);
- u32 id;
-
- if (get_user_cast(id, &kcontrols->id) ||
- put_user(id, &ucontrols->id) ||
- assign_in_user_cast(&ucontrols->size, &kcontrols->size) ||
- copy_in_user(&ucontrols->reserved2,
- (void __user *)&kcontrols->reserved2,
- sizeof(ucontrols->reserved2)))
- return -EFAULT;
-
- /*
- * Do not modify the pointer when copying a pointer control.
- * The contents of the pointer was changed, not the pointer
- * itself.
- */
- if (ctrl_is_pointer(file, id))
- size -= sizeof(ucontrols->value64);
-
- if (copy_in_user(ucontrols,
- (void __user *)kcontrols, size))
- return -EFAULT;
-
- ucontrols++;
- kcontrols++;
- }
return 0;
}

@@ -1409,6 +1311,12 @@ static int put_v4l2_edid32(struct v4l2_edid __user *p64,
unsigned int v4l2_compat_translate_cmd(unsigned int cmd)
{
switch (cmd) {
+ case VIDIOC_G_EXT_CTRLS32:
+ return VIDIOC_G_EXT_CTRLS;
+ case VIDIOC_S_EXT_CTRLS32:
+ return VIDIOC_S_EXT_CTRLS;
+ case VIDIOC_TRY_EXT_CTRLS32:
+ return VIDIOC_TRY_EXT_CTRLS;
}
return cmd;
}
@@ -1416,6 +1324,10 @@ unsigned int v4l2_compat_translate_cmd(unsigned int cmd)
int v4l2_compat_get_user(void __user *arg, void *parg, unsigned int cmd)
{
switch (cmd) {
+ case VIDIOC_G_EXT_CTRLS32:
+ case VIDIOC_S_EXT_CTRLS32:
+ case VIDIOC_TRY_EXT_CTRLS32:
+ return get_v4l2_ext_controls32(parg, arg);
}
return 0;
}
@@ -1423,6 +1335,10 @@ int v4l2_compat_get_user(void __user *arg, void *parg, unsigned int cmd)
int v4l2_compat_put_user(void __user *arg, void *parg, unsigned int cmd)
{
switch (cmd) {
+ case VIDIOC_G_EXT_CTRLS32:
+ case VIDIOC_S_EXT_CTRLS32:
+ case VIDIOC_TRY_EXT_CTRLS32:
+ return put_v4l2_ext_controls32(parg, arg);
}
return 0;
}
@@ -1434,6 +1350,29 @@ int v4l2_compat_get_array_args(struct file *file, void *mbuf,
int err = 0;

switch (cmd) {
+ case VIDIOC_G_EXT_CTRLS32:
+ case VIDIOC_S_EXT_CTRLS32:
+ case VIDIOC_TRY_EXT_CTRLS32: {
+ struct v4l2_ext_controls *ecs64 = arg;
+ struct v4l2_ext_control *ec64 = mbuf;
+ struct v4l2_ext_control32 __user *ec32 = user_ptr;
+ int n;
+
+ for (n = 0; n < ecs64->count; n++) {
+ if (copy_from_user(ec64, ec32, sizeof(*ec32)))
+ return -EFAULT;
+
+ if (ctrl_is_pointer(file, ec64->id)) {
+ compat_uptr_t p;
+ if (get_user(p, &ec32->string))
+ return -EFAULT;
+ ec64->string = compat_ptr(p);
+ }
+ ec32++;
+ ec64++;
+ }
+ break;
+ }
default:
if (copy_from_user(mbuf, user_ptr, array_size))
err = -EFAULT;
@@ -1450,6 +1389,33 @@ int v4l2_compat_put_array_args(struct file *file, void __user *user_ptr,
int err = 0;

switch (cmd) {
+ case VIDIOC_G_EXT_CTRLS32:
+ case VIDIOC_S_EXT_CTRLS32:
+ case VIDIOC_TRY_EXT_CTRLS32: {
+ struct v4l2_ext_controls *ecs64 = arg;
+ struct v4l2_ext_control *ec64 = mbuf;
+ struct v4l2_ext_control32 __user *ec32 = user_ptr;
+ int n;
+
+ for (n = 0; n < ecs64->count; n++) {
+ unsigned int size = sizeof(*ec32);
+ /*
+ * Do not modify the pointer when copying a pointer
+ * control. The contents of the pointer was changed,
+ * not the pointer itself.
+ * The structures are otherwise compatible.
+ */
+ if (ctrl_is_pointer(file, ec64->id))
+ size -= sizeof(ec32->value64);
+
+ if (copy_to_user(ec32, ec64, size))
+ return -EFAULT;
+
+ ec32++;
+ ec64++;
+ }
+ break;
+ }
default:
if (copy_to_user(user_ptr, mbuf, array_size))
err = -EFAULT;
@@ -1459,6 +1425,7 @@ int v4l2_compat_put_array_args(struct file *file, void __user *user_ptr,
return err;
}

+
/**
* alloc_userspace() - Allocates a 64-bits userspace pointer compatible
* for calling the native 64-bits version of an ioctl.
@@ -1529,9 +1496,6 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
case VIDIOC_ENUMSTD32: ncmd = VIDIOC_ENUMSTD; break;
case VIDIOC_ENUMINPUT32: ncmd = VIDIOC_ENUMINPUT; break;
case VIDIOC_TRY_FMT32: ncmd = VIDIOC_TRY_FMT; break;
- case VIDIOC_G_EXT_CTRLS32: ncmd = VIDIOC_G_EXT_CTRLS; break;
- case VIDIOC_S_EXT_CTRLS32: ncmd = VIDIOC_S_EXT_CTRLS; break;
- case VIDIOC_TRY_EXT_CTRLS32: ncmd = VIDIOC_TRY_EXT_CTRLS; break;
#ifdef CONFIG_X86_64
case VIDIOC_DQEVENT32: ncmd = VIDIOC_DQEVENT; break;
case VIDIOC_DQEVENT32_TIME32: ncmd = VIDIOC_DQEVENT_TIME32; break;
@@ -1647,20 +1611,6 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
compatible_arg = 0;
break;

- case VIDIOC_G_EXT_CTRLS32:
- case VIDIOC_S_EXT_CTRLS32:
- case VIDIOC_TRY_EXT_CTRLS32:
- err = bufsize_v4l2_ext_controls(p32, &aux_space);
- if (!err)
- err = alloc_userspace(sizeof(struct v4l2_ext_controls),
- aux_space, &new_p64);
- if (!err) {
- aux_buf = new_p64 + sizeof(struct v4l2_ext_controls);
- err = get_v4l2_ext_controls32(file, new_p64, p32,
- aux_buf, aux_space);
- }
- compatible_arg = 0;
- break;
#ifdef CONFIG_X86_64
case VIDIOC_DQEVENT32:
err = alloc_userspace(sizeof(struct v4l2_event), 0, &new_p64);
@@ -1703,12 +1653,6 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
* the blocks to maximum allowed value.
*/
switch (cmd) {
- case VIDIOC_G_EXT_CTRLS32:
- case VIDIOC_S_EXT_CTRLS32:
- case VIDIOC_TRY_EXT_CTRLS32:
- if (put_v4l2_ext_controls32(file, new_p64, p32))
- err = -EFAULT;
- break;
case VIDIOC_S_EDID32:
if (put_v4l2_edid32(new_p64, p32))
err = -EFAULT;
--
2.27.0