为啥 Python pyusb usb.core 访问由于权限而被拒绝，为啥 rules.d 不能修复它？

Posted 2023-02-19

【中文标题】为啥 Python pyusb usb.core 访问由于权限而被拒绝，为啥 rules.d 不能修复它？

【英文标题】：Why is Python pyusb usb.core access denied due to permissions and why won't the rules.d fix it?为什么 Python pyusb usb.core 访问由于权限而被拒绝，为什么 rules.d 不能修复它？

【发布时间】：2019-04-07 02:01:50

【问题描述】：

我有一个 USB 设备，我想在 linux 上使用 pyusb 1.0.2 与之交谈（Linux tpad 4.15.0-38-generic #41~16.04.1-Ubuntu SMP Wed Oct 10 20:16:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux）。运行 python 3.5 我得到以下错误（这篇文章底部的完整跟踪）：

usb.core.USBError: [Errno 13] Access denied (insufficient permissions)

安装 USB 并使用 lsusb 然后检查它：

udevadm info -a -p $(udevadm info -q path -n /dev/bus/usb/006/011)

表演

    looking at device '/devices/pci0000:00/0000:00:10.0/usb6/6-1':
        KERNEL=="6-1"
        SUBSYSTEM=="usb"
        DRIVER=="usb"
        ATTRauthorized=="1"
        ATTRavoid_reset_quirk=="0"
        ATTRbConfigurationValue=="1"
        ATTRbDeviceClass=="00"
        ATTRbDeviceProtocol=="00"
        ATTRbDeviceSubClass=="00"
        ATTRbMaxPacketSize0=="8"
        ATTRbMaxPower=="98mA"
        ATTRbNumConfigurations=="1"
        ATTRbNumInterfaces==" 1"
        ATTRbcdDevice=="0111"
        ATTRbmAttributes=="80"
        ATTRbusnum=="6"
        ATTRconfiguration==""
        ATTRdevnum=="11"
        ATTRdevpath=="1"
        ATTRidProduct=="0001"
        ATTRidVendor=="17a4"
        ATTRltm_capable=="no"
        ATTRmanufacturer=="Concept2"
        ATTRmaxchild=="0"
        ATTRproduct=="Concept2 Performance Monitor 3 (PM3)"
        ATTRquirks=="0x0"
        ATTRremovable=="unknown"
        ATTRserial=="300118412"
        ATTRspeed=="12"
        ATTRurbnum=="12"
        ATTRversion==" 1.10"

所以我在 /etc/udev/rules.d/10-local.rules 中写了一条这样的规则（仅供参考——我也试过“user1”，这是用户 python 显示它正在运行，我' ":=" 和 "=") 都试过了：

    SUBSYSTEMS=="usb", ATTRSidVendor=="17a4", ATTRSidProduct=="0001", GROUP:="users", MODE="0777"

然后我运行了 udevadm test /devices/pci0000:00/0000:00:10.0/usb6/6-1

其中显示：

calling: test
version 229
This program is for debugging only, it does not run any program
specified by a RUN key. It may show incorrect results, because
some values may be different, or not available at a simulation run.

=== trie on-disk ===
tool version:          229
file size:         7049340 bytes
header size             80 bytes
strings            1759644 bytes
nodes              5289616 bytes
Load module index
timestamp of '/etc/systemd/network' changed
timestamp of '/lib/systemd/network' changed
Parsed configuration file /lib/systemd/network/99-default.link
Created link configuration context.
timestamp of '/etc/udev/rules.d' changed
Reading rules file: /etc/udev/rules.d/10-local.rules
Reading rules file: /lib/udev/rules.d/40-crda.rules
[removed long list of rule files...]
Skipping empty file: /etc/udev/rules.d/99-usbftdi.rules
rules contain 393216 bytes tokens (32768 * 12 bytes), 33403 bytes strings
25688 strings (211409 bytes), 22263 de-duplicated (181432 bytes), 3426 trie nodes used
GROUP 100 /etc/udev/rules.d/10-local.rules:1
MODE 0777 /etc/udev/rules.d/10-local.rules:1
value '[dmi/id]sys_vendor' is 'LENOVO'
value '[dmi/id]sys_vendor' is 'LENOVO'
IMPORT builtin 'usb_id' /lib/udev/rules.d/50-udev-default.rules:13
IMPORT builtin 'hwdb' /lib/udev/rules.d/50-udev-default.rules:13
MODE 0664 /lib/udev/rules.d/50-udev-default.rules:41
PROGRAM 'mtp-probe /sys/devices/pci0000:00/0000:00:10.0/usb6/6-1 6 11' /lib/udev/rules.d/69-libmtp.rules:1923
starting 'mtp-probe /sys/devices/pci0000:00/0000:00:10.0/usb6/6-1 6 11'
'mtp-probe /sys/devices/pci0000:00/0000:00:10.0/usb6/6-1 6 11'(out) '0'
Process 'mtp-probe /sys/devices/pci0000:00/0000:00:10.0/usb6/6-1 6 11' succeeded.
handling device node '/dev/bus/usb/006/011', devnum=c189:650, mode=0664, uid=0, gid=100
set permissions /dev/bus/usb/006/011, 020664, uid=0, gid=100
setting mode of /dev/bus/usb/006/011 to 020664 failed: Operation not permitted
setting owner of /dev/bus/usb/006/011 to uid=0, gid=100 failed: Operation not permitted
ACTION=add
BUSNUM=006
DEVNAME=/dev/bus/usb/006/011
DEVNUM=011
DEVPATH=/devices/pci0000:00/0000:00:10.0/usb6/6-1
DEVTYPE=usb_device
DRIVER=usb
ID_BUS=usb
ID_MODEL=Concept2_Performance_Monitor_3__PM3_
ID_MODEL_ENC=Concept2\x20Performance\x20Monitor\x203\x20\x28PM3\x29
ID_MODEL_FROM_DATABASE=Performance Monitor 3
ID_MODEL_ID=0001
ID_REVISION=0111
ID_SERIAL=Concept2_Concept2_Performance_Monitor_3__PM3__300118412
ID_SERIAL_SHORT=300118412
ID_USB_INTERFACES=:030000:
ID_VENDOR=Concept2
ID_VENDOR_ENC=Concept2
ID_VENDOR_FROM_DATABASE=Concept2
ID_VENDOR_ID=17a4
MAJOR=189
MINOR=650
PRODUCT=17a4/1/111
SUBSYSTEM=usb
TYPE=0/0/0
USEC_INITIALIZED=3850171749
Unload module index
Unloaded link configuration context.

但是，在执行此操作后，python 仍然会向 USB 设备报告访问错误。

Traceback (most recent call last):
  File "/home/user1/PycharmProjects/PyRow/statshow.py", line 22, in <module>
    erg = pyrow.pyrow(ergs[0])
  File "/home/user1/PycharmProjects/PyRow/pyrow.py", line 61, in __init__
    usb.util.claim_interface(erg, INTERFACE)
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/util.py", line 205, in claim_interface
    device._ctx.managed_claim_interface(device, interface)
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/core.py", line 102, in wrapper
    return f(self, *args, **kwargs)
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/core.py", line 159, in managed_claim_interface
    self.managed_open()
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/core.py", line 102, in wrapper
    return f(self, *args, **kwargs)
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/core.py", line 120, in managed_open
    self.handle = self.backend.open_device(self.dev)
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/backend/libusb1.py", line 786, in open_device
    return _DeviceHandle(dev)
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/backend/libusb1.py", line 643, in __init__
    _check(_lib.libusb_open(self.devid, byref(self.handle)))
  File "/home/user1/PycharmProjects/camera/venv/lib/python3.5/site-packages/usb/backend/libusb1.py", line 595, in _check
    raise USBError(_strerror(ret), ret, _libusb_errno[ret])
usb.core.USBError: [Errno 13] Access denied (insufficient permissions)

我不知道如何解决这个问题。有什么建议吗？

【参考方案1】：

使用this answer 我发现我可以使用plugdev 组更正权限问题。

所以在我使用的终端中

groups
groups [myuserid]

并且经过验证的 plugdev 在那里，并且该用户是该组的一部分。然后我把下面这行放在 /etc/udev/rules.d/10-local.rules

SUBSYSTEMS=="usb", ENVDEVTYPE=="usb_device", ATTRSidVendor=="17a4", ATTRSidProduct=="0001", GROUP="plugdev", MODE="0777"

我不确定 devtype 以及 0777 或 0666 是否正确，但这是有效的。

进行更改后，我还运行了以下命令来重置系统规则：

sudo udevadm control --reload
sudo udevadm trigger