@@ -42,6 +42,9 @@ static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count,
int ret = 0, len;
DECLARE_WAITQUEUE(wait, current);
+ if (list->revoked)
+ return -ENODEV;
+
mutex_lock(&list->read_mutex);
while (ret == 0) {
@@ -159,9 +162,13 @@ static ssize_t hidraw_send_report(struct file *file, const char __user *buffer,
static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
{
+ struct hidraw_list *list = file->private_data;
ssize_t ret;
down_read(&minors_rwsem);
- ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT);
+ if (list->revoked)
+ ret = -ENODEV;
+ else
+ ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT);
up_read(&minors_rwsem);
return ret;
}
@@ -254,7 +261,7 @@ static __poll_t hidraw_poll(struct file *file, poll_table *wait)
poll_wait(file, &list->hidraw->wait, wait);
if (list->head != list->tail)
mask |= EPOLLIN | EPOLLRDNORM;
- if (!list->hidraw->exist)
+ if (!list->hidraw->exist || list->revoked)
mask |= EPOLLERR | EPOLLHUP;
return mask;
}
@@ -313,6 +320,9 @@ static int hidraw_fasync(int fd, struct file *file, int on)
{
struct hidraw_list *list = file->private_data;
+ if (list->revoked)
+ return -ENODEV;
+
return fasync_helper(fd, file, on, &list->fasync);
}
@@ -360,6 +370,13 @@ static int hidraw_release(struct inode * inode, struct file * file)
return 0;
}
+static int hidraw_revoke(struct hidraw_list *list, struct file *file)
+{
+ list->revoked = true;
+
+ return 0;
+}
+
static long hidraw_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
@@ -367,11 +384,12 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
unsigned int minor = iminor(inode);
long ret = 0;
struct hidraw *dev;
+ struct hidraw_list *list = file->private_data;
void __user *user_arg = (void __user*) arg;
down_read(&minors_rwsem);
dev = hidraw_table[minor];
- if (!dev || !dev->exist) {
+ if (!dev || !dev->exist || list->revoked) {
ret = -ENODEV;
goto out;
}
@@ -409,6 +427,14 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
ret = -EFAULT;
break;
}
+ case HIDIOCREVOKE:
+ {
+ if (user_arg)
+ ret = -EINVAL;
+ else
+ ret = hidraw_revoke(list, file);
+ break;
+ }
default:
{
struct hid_device *hid = dev->hid;
@@ -515,7 +541,7 @@ int hidraw_report_event(struct hid_device *hid, u8 *data, int len)
list_for_each_entry(list, &dev->list, node) {
int new_head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);
- if (new_head == list->tail)
+ if (list->revoked || new_head == list->tail)
continue;
if (!(list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC))) {
@@ -32,6 +32,7 @@ struct hidraw_list {
struct hidraw *hidraw;
struct list_head node;
struct mutex read_mutex;
+ bool revoked;
};
#ifdef CONFIG_HIDRAW
@@ -46,6 +46,7 @@ struct hidraw_devinfo {
/* The first byte of SOUTPUT and GOUTPUT is the report number */
#define HIDIOCSOUTPUT(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x0B, len)
#define HIDIOCGOUTPUT(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x0C, len)
+#define HIDIOCREVOKE _IOW('H', 0x0D, int) /* Revoke device access */
#define HIDRAW_FIRST_MINOR 0
#define HIDRAW_MAX_DEVICES 64
There is a need for userspace applications to open HID devices directly. Use-cases include configuration of gaming mice or direct access to joystick devices. The latter is currently handled by the uaccess tag in systemd, other devices include more custom/local configurations or just sudo. A better approach is what we already have for evdev devices: give the application a file descriptor and revoke it when it may no longer access that device. This patch is the hidraw equivalent to the EVIOCREVOKE ioctl, see commit c7dc65737c9a607d3e6f8478659876074ad129b8 for full details. A draft MR for systemd-logind has been filed here: https://github.com/systemd/systemd/pull/23140 Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net> --- Maybe noteworthy: even with logind support this is only the first step of many. logind only hands the fd to whoever controls the session and the fd will then have to be passed forward through portals to the application. drivers/hid/hidraw.c | 34 ++++++++++++++++++++++++++++++---- include/linux/hidraw.h | 1 + include/uapi/linux/hidraw.h | 1 + 3 files changed, 32 insertions(+), 4 deletions(-)