[PATCH 1/8] media: v4l2: prepare compat-ioctl rework
From: Arnd Bergmann
Date: Thu Sep 17 2020 - 11:31:16 EST
The v4l2-compat-ioctl32() currently takes an extra round trip through user
space pointers when converting the data structure formats. In particular,
this involves using the compat_alloc_user_space() and copy_in_user()
helpers that often lead to worse compat handlers compared to using
in_compat_syscall() checks when copying the data.
The native implementation already gained a simpler method to deal with
the conversion for the time32 conversion. Hook into the same places to
provide a location for reading and writing user space data from inside
of the generic video_usercopy() helper.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 53 ++++++++++
drivers/media/v4l2-core/v4l2-ioctl.c | 97 ++++++++++++-------
include/media/v4l2-ioctl.h | 11 +++
3 files changed, 125 insertions(+), 36 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
index 593bcf6c3735..8f2cb03be48b 100644
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -1420,6 +1420,59 @@ static int put_v4l2_edid32(struct v4l2_edid __user *p64,
#define VIDIOC_G_OUTPUT32 _IOR ('V', 46, s32)
#define VIDIOC_S_OUTPUT32 _IOWR('V', 47, s32)
+unsigned int v4l2_compat_translate_cmd(unsigned int cmd)
+{
+ switch (cmd) {
+ }
+ return cmd;
+}
+
+int v4l2_compat_get_user(void __user *arg, void *parg, unsigned int cmd)
+{
+ switch (cmd) {
+ }
+ return 0;
+}
+
+int v4l2_compat_put_user(void __user *arg, void *parg, unsigned int cmd)
+{
+ switch (cmd) {
+ }
+ return 0;
+}
+
+int v4l2_compat_get_array_args(struct file *file, void *mbuf,
+ void __user *user_ptr, size_t array_size,
+ unsigned int cmd, void *arg)
+{
+ int err = 0;
+
+ switch (cmd) {
+ default:
+ if (copy_from_user(mbuf, user_ptr, array_size))
+ err = -EFAULT;
+ break;
+ }
+
+ return err;
+}
+
+int v4l2_compat_put_array_args(struct file *file, void __user *user_ptr,
+ void *mbuf, size_t array_size,
+ unsigned int cmd, void *arg)
+{
+ int err = 0;
+
+ switch (cmd) {
+ default:
+ if (copy_to_user(user_ptr, mbuf, array_size))
+ err = -EFAULT;
+ break;
+ }
+
+ return err;
+}
+
/**
* alloc_userspace() - Allocates a 64-bits userspace pointer compatible
* for calling the native 64-bits version of an ioctl.
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index a556880f225a..4e79cdac9a5f 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -8,6 +8,7 @@
* Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> (version 2)
*/
+#include <linux/compat.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
@@ -3103,11 +3104,14 @@ static unsigned int video_translate_cmd(unsigned int cmd)
return VIDIOC_PREPARE_BUF;
#endif
}
+ if (in_compat_syscall())
+ return v4l2_compat_translate_cmd(cmd);
return cmd;
}
-static int video_get_user(void __user *arg, void *parg, unsigned int cmd,
+static int video_get_user(void __user *arg, void *parg,
+ unsigned int real_cmd, unsigned int cmd,
bool *always_copy)
{
unsigned int n = _IOC_SIZE(cmd);
@@ -3118,6 +3122,34 @@ static int video_get_user(void __user *arg, void *parg, unsigned int cmd,
return 0;
}
+ if (cmd == real_cmd) {
+ /*
+ * In some cases, only a few fields are used as input,
+ * i.e. when the app sets "index" and then the driver
+ * fills in the rest of the structure for the thing
+ * with that index. We only need to copy up the first
+ * non-input field.
+ */
+ if (v4l2_is_known_ioctl(cmd)) {
+ u32 flags = v4l2_ioctls[_IOC_NR(cmd)].flags;
+
+ if (flags & INFO_FL_CLEAR_MASK)
+ n = (flags & INFO_FL_CLEAR_MASK) >> 16;
+ *always_copy = flags & INFO_FL_ALWAYS_COPY;
+ }
+
+ if (copy_from_user(parg, (void __user *)arg, n))
+ return -EFAULT;
+
+ /* zero out anything we don't copy from userspace */
+ if (n < _IOC_SIZE(cmd))
+ memset((u8 *)parg + n, 0, _IOC_SIZE(cmd) - n);
+ return 0;
+ }
+
+ if (in_compat_syscall())
+ return v4l2_compat_get_user(arg, parg, cmd);
+
switch (cmd) {
#ifdef CONFIG_COMPAT_32BIT_TIME
case VIDIOC_QUERYBUF_TIME32:
@@ -3152,39 +3184,26 @@ static int video_get_user(void __user *arg, void *parg, unsigned int cmd,
break;
}
#endif
- default:
- /*
- * In some cases, only a few fields are used as input,
- * i.e. when the app sets "index" and then the driver
- * fills in the rest of the structure for the thing
- * with that index. We only need to copy up the first
- * non-input field.
- */
- if (v4l2_is_known_ioctl(cmd)) {
- u32 flags = v4l2_ioctls[_IOC_NR(cmd)].flags;
-
- if (flags & INFO_FL_CLEAR_MASK)
- n = (flags & INFO_FL_CLEAR_MASK) >> 16;
- *always_copy = flags & INFO_FL_ALWAYS_COPY;
- }
-
- if (copy_from_user(parg, (void __user *)arg, n))
- return -EFAULT;
-
- /* zero out anything we don't copy from userspace */
- if (n < _IOC_SIZE(cmd))
- memset((u8 *)parg + n, 0, _IOC_SIZE(cmd) - n);
- break;
}
-
return 0;
}
-static int video_put_user(void __user *arg, void *parg, unsigned int cmd)
+static int video_put_user(void __user *arg, void *parg,
+ unsigned int real_cmd, unsigned int cmd)
{
if (!(_IOC_DIR(cmd) & _IOC_READ))
return 0;
+ if (cmd == real_cmd) {
+ /* Copy results into user buffer */
+ if (copy_to_user(arg, parg, _IOC_SIZE(cmd)))
+ return -EFAULT;
+ return 0;
+ }
+
+ if (in_compat_syscall())
+ return v4l2_compat_put_user(arg, parg, cmd);
+
switch (cmd) {
#ifdef CONFIG_COMPAT_32BIT_TIME
case VIDIOC_DQEVENT_TIME32: {
@@ -3231,11 +3250,6 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd)
break;
}
#endif
- default:
- /* Copy results into user buffer */
- if (copy_to_user(arg, parg, _IOC_SIZE(cmd)))
- return -EFAULT;
- break;
}
return 0;
@@ -3269,8 +3283,8 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
parg = mbuf;
}
- err = video_get_user((void __user *)arg, parg, orig_cmd,
- &always_copy);
+ err = video_get_user((void __user *)arg, parg, cmd,
+ orig_cmd, &always_copy);
if (err)
goto out;
}
@@ -3292,7 +3306,14 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
if (NULL == mbuf)
goto out_array_args;
err = -EFAULT;
- if (copy_from_user(mbuf, user_ptr, array_size))
+ if (in_compat_syscall())
+ err = v4l2_compat_get_array_args(file, mbuf, user_ptr,
+ array_size, orig_cmd,
+ parg);
+ else
+ err = copy_from_user(mbuf, user_ptr, array_size) ?
+ -EFAULT : 0;
+ if (err)
goto out_array_args;
*kernel_ptr = mbuf;
}
@@ -3313,7 +3334,11 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
if (has_array_args) {
*kernel_ptr = (void __force *)user_ptr;
- if (copy_to_user(user_ptr, mbuf, array_size))
+ if (in_compat_syscall())
+ err = v4l2_compat_put_array_args(file, user_ptr, mbuf,
+ array_size, orig_cmd,
+ parg);
+ else if (copy_to_user(user_ptr, mbuf, array_size))
err = -EFAULT;
goto out_array_args;
}
@@ -3325,7 +3350,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
goto out;
out_array_args:
- if (video_put_user((void __user *)arg, parg, orig_cmd))
+ if (video_put_user((void __user *)arg, parg, cmd, orig_cmd))
err = -EFAULT;
out:
kvfree(mbuf);
diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index 86878fba332b..0db79f36c496 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -686,6 +686,17 @@ long int v4l2_compat_ioctl32(struct file *file, unsigned int cmd,
unsigned long arg);
#endif
+unsigned int v4l2_compat_translate_cmd(unsigned int cmd);
+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);
+int v4l2_compat_get_array_args(struct file *file, void *mbuf,
+ void __user *user_ptr, size_t array_size,
+ unsigned int cmd, void *arg);
+int v4l2_compat_put_array_args(struct file *file, void __user *user_ptr,
+ void *mbuf, size_t array_size,
+ unsigned int cmd, void *arg);
+
+
/**
* typedef v4l2_kioctl - Typedef used to pass an ioctl handler.
*
--
2.27.0