From b31c9d9dc343146b9f4ce67b4eee748c49296e99 Mon Sep 17 00:00:00 2001 From: Peter Hutterer Date: Tue, 27 Aug 2024 17:19:29 +0900 Subject: [PATCH] HID: hidraw: add HIDIOCREVOKE ioctl 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 c7dc65737c9a ("Input: evdev - add EVIOCREVOKE ioctl") for full details. An MR for systemd-logind has been filed here: https://github.com/systemd/systemd/pull/33970 Signed-off-by: Peter Hutterer Link: https://patch.msgid.link/20240827-hidraw-revoke-v5-1-d004a7451aea@kernel.org Signed-off-by: Benjamin Tissoires --- drivers/hid/hidraw.c | 39 +++++++++++++++++++++++++++++++++---- include/linux/hidraw.h | 1 + include/uapi/linux/hidraw.h | 1 + 3 files changed, 37 insertions(+), 4 deletions(-) diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c index 716294e40e8a..c887f48756f4 100644 --- a/drivers/hid/hidraw.c +++ b/drivers/hid/hidraw.c @@ -38,12 +38,20 @@ static const struct class hidraw_class = { static struct hidraw *hidraw_table[HIDRAW_MAX_DEVICES]; static DECLARE_RWSEM(minors_rwsem); +static inline bool hidraw_is_revoked(struct hidraw_list *list) +{ + return list->revoked; +} + static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct hidraw_list *list = file->private_data; int ret = 0, len; DECLARE_WAITQUEUE(wait, current); + if (hidraw_is_revoked(list)) + return -ENODEV; + mutex_lock(&list->read_mutex); while (ret == 0) { @@ -161,9 +169,13 @@ out: 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 (hidraw_is_revoked(list)) + ret = -ENODEV; + else + ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT); up_read(&minors_rwsem); return ret; } @@ -256,7 +268,7 @@ 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 || hidraw_is_revoked(list)) mask |= EPOLLERR | EPOLLHUP; return mask; } @@ -320,6 +332,9 @@ static int hidraw_fasync(int fd, struct file *file, int on) { struct hidraw_list *list = file->private_data; + if (hidraw_is_revoked(list)) + return -ENODEV; + return fasync_helper(fd, file, on, &list->fasync); } @@ -372,6 +387,13 @@ static int hidraw_release(struct inode * inode, struct file * file) return 0; } +static int hidraw_revoke(struct hidraw_list *list) +{ + list->revoked = true; + + return 0; +} + static long hidraw_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { @@ -379,11 +401,12 @@ 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 || hidraw_is_revoked(list)) { ret = -ENODEV; goto out; } @@ -421,6 +444,14 @@ 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); + break; + } default: { struct hid_device *hid = dev->hid; @@ -527,7 +558,7 @@ 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 (hidraw_is_revoked(list) || new_head == list->tail) continue; if (!(list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC))) { diff --git a/include/linux/hidraw.h b/include/linux/hidraw.h index cd67f4ca5599..18fd30a288de 100644 --- a/include/linux/hidraw.h +++ b/include/linux/hidraw.h @@ -32,6 +32,7 @@ struct hidraw_list { struct hidraw *hidraw; struct list_head node; struct mutex read_mutex; + bool revoked; }; #ifdef CONFIG_HIDRAW diff --git a/include/uapi/linux/hidraw.h b/include/uapi/linux/hidraw.h index 33ebad81720a..d5ee269864e0 100644 --- a/include/uapi/linux/hidraw.h +++ b/include/uapi/linux/hidraw.h @@ -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