Ubuntu Server 17.04 - regra (s) do udev para o drive Blu-Ray

Question

Estou tentando criar uma regra udev que permitirá que usuários não-raiz montem um disco inserido na unidade Blu-Ray em um ponto de montagem arbitrário.

Como a unidade é permanente, mas os discos não são, não estou usando /etc/fstab - meu entendimento, que pode estar errado, é que /etc/fstab não é apropriado para essa situação.

Eu criei um arquivo chamado 10-bluray.rules na minha página inicial não raiz e criei um link simbólico para /etc/udev/rules.d/10-bluray.rules . A regra que defini é:

ACTION=="change", SUBSYSTEM=="block", KERNEL=="sr[0-9]*", ENV{ID_CDROM_MEDIA_STATE}=="complete", GROUP="users"

Ainda depois de executar sudo udevadm control --reload-rules e ejetar e inserir um disco, meu /dev ainda é assim:

brw-rw---- 1 root cdrom    11,   0 2017-09-09 00:52 sr0
lrwxrwxrwx 1 root root           3 2017-09-09 00:52 dvdrw -> sr0
lrwxrwxrwx 1 root root           3 2017-09-09 00:52 dvd -> sr0
lrwxrwxrwx 1 root root           3 2017-09-09 00:52 cdrw -> sr0
lrwxrwxrwx 1 root root           3 2017-09-09 00:52 cdrom -> sr0

Com o grupo definido como cdrom em vez de users , conforme especificado na regra udev .

Até chequei com sudo udevadm test /dev/sr0 e isso não indica problemas com as regras:

=== trie on-disk ===
tool version:          232
file size:         8775171 bytes
header size             80 bytes
strings            1849483 bytes
nodes              6925608 bytes
Load module index
Found container virtualization none
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-bluray.rules
Reading rules file: /lib/udev/rules.d/40-vm-hotadd.rules
Reading rules file: /lib/udev/rules.d/50-apport.rules
Reading rules file: /lib/udev/rules.d/50-firmware.rules
Reading rules file: /lib/udev/rules.d/50-udev-default.rules
Reading rules file: /etc/udev/rules.d/51-android.rules
Reading rules file: /lib/udev/rules.d/55-dm.rules
Reading rules file: /lib/udev/rules.d/56-lvm.rules
Reading rules file: /lib/udev/rules.d/60-block.rules
Reading rules file: /lib/udev/rules.d/60-bridge-network-interface.rules
Reading rules file: /lib/udev/rules.d/60-cdrom_id.rules
Reading rules file: /lib/udev/rules.d/60-crda.rules
Reading rules file: /lib/udev/rules.d/60-drm.rules
Reading rules file: /lib/udev/rules.d/60-evdev.rules
Reading rules file: /lib/udev/rules.d/60-libgphoto2-6.rules
Reading rules file: /lib/udev/rules.d/60-libsane.rules
Reading rules file: /lib/udev/rules.d/60-open-vm-tools.rules
Reading rules file: /lib/udev/rules.d/60-persistent-alsa.rules
Reading rules file: /lib/udev/rules.d/60-persistent-input.rules
Reading rules file: /lib/udev/rules.d/60-persistent-storage-dm.rules
Reading rules file: /lib/udev/rules.d/60-persistent-storage-tape.rules
Reading rules file: /lib/udev/rules.d/60-persistent-storage.rules
Reading rules file: /lib/udev/rules.d/60-persistent-v4l.rules
Reading rules file: /lib/udev/rules.d/60-qemu-system-common.rules
Reading rules file: /lib/udev/rules.d/60-serial.rules
Reading rules file: /lib/udev/rules.d/60-tvbutler-perms.rules
Reading rules file: /lib/udev/rules.d/60-vlan-network-interface.rules
Reading rules file: /lib/udev/rules.d/61-persistent-storage-android.rules
Reading rules file: /lib/udev/rules.d/63-md-raid-arrays.rules
Reading rules file: /lib/udev/rules.d/64-btrfs-dm.rules
Reading rules file: /lib/udev/rules.d/64-btrfs.rules
Reading rules file: /lib/udev/rules.d/64-md-raid-assembly.rules
Reading rules file: /lib/udev/rules.d/66-snapd-autoimport.rules
Reading rules file: /lib/udev/rules.d/69-bcache.rules
Reading rules file: /lib/udev/rules.d/69-cd-sensors.rules
Reading rules file: /lib/udev/rules.d/69-libmtp.rules
Reading rules file: /lib/udev/rules.d/69-lvm-metad.rules
Reading rules file: /lib/udev/rules.d/70-android-tools-adb.rules
Reading rules file: /lib/udev/rules.d/70-android-tools-fastboot.rules
Reading rules file: /lib/udev/rules.d/70-debian-uaccess.rules
Reading rules file: /lib/udev/rules.d/70-iscsi-network-interface.rules
Reading rules file: /lib/udev/rules.d/70-mouse.rules
Reading rules file: /lib/udev/rules.d/70-power-switch.rules
Reading rules file: /etc/udev/rules.d/70-snap.core.rules
Reading rules file: /lib/udev/rules.d/70-touchpad.rules
Reading rules file: /lib/udev/rules.d/70-uaccess.rules
Reading rules file: /lib/udev/rules.d/71-power-switch-proliant.rules
Reading rules file: /lib/udev/rules.d/71-seat.rules
Reading rules file: /lib/udev/rules.d/71-u-d-c-gpu-detection.rules
Reading rules file: /lib/udev/rules.d/73-seat-late.rules
Reading rules file: /lib/udev/rules.d/73-special-net-names.rules
Reading rules file: /lib/udev/rules.d/73-usb-net-by-mac.rules
Reading rules file: /lib/udev/rules.d/75-net-description.rules
Reading rules file: /lib/udev/rules.d/75-probe_mtd.rules
Reading rules file: /lib/udev/rules.d/78-graphics-card.rules
Reading rules file: /lib/udev/rules.d/78-sound-card.rules
Reading rules file: /lib/udev/rules.d/80-debian-compat.rules
Reading rules file: /lib/udev/rules.d/80-docker.io.rules
Reading rules file: /lib/udev/rules.d/80-drivers.rules
Reading rules file: /lib/udev/rules.d/80-ifupdown.rules
Reading rules file: /lib/udev/rules.d/80-net-setup-link.rules
Reading rules file: /lib/udev/rules.d/80-snappy-assign.rules
Reading rules file: /lib/udev/rules.d/80-udisks2.rules
Reading rules file: /lib/udev/rules.d/85-hdparm.rules
Reading rules file: /lib/udev/rules.d/85-keyboard-configuration.rules
Reading rules file: /lib/udev/rules.d/85-regulatory.rules
Reading rules file: /lib/udev/rules.d/90-alsa-restore.rules
Reading rules file: /lib/udev/rules.d/90-console-setup.rules
Reading rules file: /lib/udev/rules.d/95-cd-devices.rules
Reading rules file: /lib/udev/rules.d/99-systemd.rules
Reading rules file: /lib/udev/rules.d/99-vmware-scsi-udev.rules
rules contain 393216 bytes tokens (32768 * 12 bytes), 31005 bytes strings
21448 strings (173557 bytes), 18376 de-duplicated (145625 bytes), 3073 trie nodes used
unable to open device '/sys/dev/sr0'
Unload module index
Unloaded link configuration context.

Meu entendimento do processamento da regra udev é que as regras em /etc/udev/rules.d/ substituem quaisquer regras definidas em /lib/udev/rules.d/ (que é onde a maioria delas é, aparentemente) - isso não está correto?

Por fim, meu objetivo é permitir que um usuário emita mount /dev/sr0 /<blah>/<blah> sem o uso de sudo - isso é possível?

    

Answer 1

• AFAIK, a maneira correta de fornecer aos usuários regulares acesso ao CDROM é adicioná-los ao grupo cdrom .

  1. Adicionar usuários existentes a cdrom group
  2. Adicione cdrom group aos grupos padrão de useradd em /etc/default/useradd file. Referência: Razões por trás dos grupos e usuários padrão no Linux

• Se você ainda quiser tentar a abordagem udev .

  Sim, as regras em /etc substituem as de /lib , mas apenas as que correspondem ao mesmo nome de arquivo nas duas pastas. Portanto, todos os outros arquivos com nome exclusivo não são omitidos.

  1. Para mim, usar 10- de ordem muito baixa não é bom para regras personalizadas do usuário. Qualquer regra com >10- (ordem alfanumérica) que defina o GROUP também para o mesmo nó substituirá sua regra personalizada. Portanto, tente alterá-lo para 99- ou 90- , pelo menos.

  2. Para ACTION=="change" , verifique se esse evento é acionado quando a unidade de CD é adicionada, se houver opção de hot plug, usando udevadm monitor . Caso contrário, use ACTION=="add" .