Hi,
this is a good improvement to the security, thanks for sharing this!
As the global socket now is at /run/wayland-0 users that belongs to group 'wayland' and want to use weston needs to set its XDG_RUNTIME_DIR accordingly. As probably more applications than weston client is using XDG_RUNTIME_DIR it is probably a bad idea to permanently set XDG_RUNTIME_DIR=/run? (Instead of standard /run/user/<uid>) In my setup I created a file /etc/profile.d/wayland.sh that make a symlink to /run/wayland-0 if the user have write permission on it.
$ cat /etc/profile.d/wayland.sh # A global socket is set up that can be used for users belonging to the wayland # group to connect to weston server. Set up a soft link to that global socket. WAYLAND_SOCKET=/run/wayland-0 [ -S $WAYLAND_SOCKET -a -w $WAYLAND_SOCKET ] && ln -s $WAYLAND_SOCKET $XDG_RUNTIME_DIR
Ya. I think maybe the problem is that will only work for an interactive shell, and wouldn't work for a service?
Also, you should avoid using the WAYLAND_SOCKET environment variable, as wayland clients will interpret that variable as a file descriptor number where a pre-connected wayland client socket is present when they start up (e.g. when weston launches a client with a pre-connected socket). I suspect the only reason this isn't causing you problems right now is because you aren't exporting it :)
If you want to make something compatible with what I've done here, you could probably get the same effect with:
if [ -s /run/wayland-0 -a -w /run/wayland-0 ]; then
export WAYLAND_DISPLAY=/run/wayland-0
fi
This will make the process a bit more automatic just creating a user and add it to the group wayland. Is this a suitable solution? Is this something that we would like upstream in the weston-init package?
Maybe. I tried really hard to make it so that you make
$XDG_RUNTIME_DIR/wayland-0 be populated from /run/wayland-0, but I
was unable to make it work (at least with systemd). The problem I
found was that the systemd units for dealing with XDG_RUNTIME_DIR
only deal with users by their UID, but we only know the user name
at compile time (since OE doesn't use fixed UIDs). As such I was
unable to get systemd to put things in the correct (UID based)
XDG_RUNTIME_DIR.
(Another side note not directly related to openembedded-core but more to HW specific setups (meta-freescale in my case) that I would like to share is that GPU device nodes also need correct permission for the weston user otherwise startup of weston application does not work (if weston using the GPU). In my case on i.Mx8 target I had to change /dev/galcore device node to video group (already prepared in udev-imx-rules package). I hope I can save time for someone else seeing this error message on a i.Mx system:
$ systemctl status weston * weston.service - Weston, a Wayland compositor, as a system service Loaded: loaded (8;;file://imx8mnevk/lib/systemd/system/weston.service/lib/systemd/system/weston.service8;;; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Fri 2020-11-27 10:11:52 UTC; 13s ago TriggeredBy: * weston.socket Docs: 8;;man:weston(1)man:weston(1)8;; 8;;man:weston.ini(5)man:weston.ini(5)8;; 8;;http://wayland.freedesktop.org/http://wayland.freedesktop.org/8;; Process: 276 ExecStart=/usr/bin/weston --modules=systemd-notify.so --log=/home/weston/weston.log (code=exited, status=1/FAILURE) Main PID: 276 (code=exited, status=1/FAILURE) Nov 27 10:11:43 imx8mnevk systemd[1]: Starting Weston, a Wayland compositor, as a system service... Nov 27 10:11:44 imx8mnevk systemd[276]: pam_unix(weston-autologin:session): session opened for user weston by (uid=0) Nov 27 10:11:52 imx8mnevk systemd[1]: weston.service: Main process exited, code=exited, status=1/FAILURE Nov 27 10:11:52 imx8mnevk systemd[1]: weston.service: Failed with result 'exit-code'. Nov 27 10:11:52 imx8mnevk systemd[1]: Failed to start Weston, a Wayland compositor, as a system service.)
That's pretty common. You could send a patch to the BSP layer to
correct the permissions.
Best regards,
/Peter
On 2020-11-19 23:58, Joshua Watt wrote:
Running the weston compositor as the root user is an insecure default behavior for OE-core. We can do much better, at least when using systemd. Change the recipe to create a dedicated "weston" user and start weston as this user. The systemd service and socket units are no longer template units, as there were several inconsistencies in the templates. Instead, there is now a global /run/wayland-0 socket that gets created, and systemd will start weston on demand when a client connects to that socket or when attempting to reach graphical.target, whichever comes first. This also allows downstream users to easily change the behavior so that weston *only* starts on demand by adding a drop file. Access to the global socket is controlled by a "wayland" group; any user that is a member of the group can use the socket to talk to the compositor. This also satisfies another use case where another systemd service might start a graphical application that needs to display with weston (e.g. a single function device in kiosk mode). Finally, the udev rules for starting weston with the existance of a DRM device have been removed. Being WantedBy= a graphical target should eliminate the need for this behavior, and having it present makes it difficult for downstream users to start weston on demand (having to override the udev rules). Signed-off-by: Joshua Watt <JPEWhacker@gmail.com> --- meta/recipes-graphics/wayland/weston-init.bb | 33 ++++++++++++------- .../wayland/weston-init/71-weston-drm.rules | 2 -- .../{weston@.service => weston.service} | 14 +++++--- .../wayland/weston-init/weston.socket | 14 ++++++++ .../wayland/weston-init/weston@.socket | 10 ------ 5 files changed, 45 insertions(+), 28 deletions(-) delete mode 100644 meta/recipes-graphics/wayland/weston-init/71-weston-drm.rules rename meta/recipes-graphics/wayland/weston-init/{weston@.service => weston.service} (83%) create mode 100644 meta/recipes-graphics/wayland/weston-init/weston.socket delete mode 100644 meta/recipes-graphics/wayland/weston-init/weston@.socket diff --git a/meta/recipes-graphics/wayland/weston-init.bb b/meta/recipes-graphics/wayland/weston-init.bb index a616c473ec..65d7b81dc5 100644 --- a/meta/recipes-graphics/wayland/weston-init.bb +++ b/meta/recipes-graphics/wayland/weston-init.bb @@ -7,9 +7,8 @@ PACKAGE_ARCH = "${MACHINE_ARCH}" SRC_URI = "file://init \ file://weston.env \ file://weston.ini \ - file://weston@.service \ - file://weston@.socket \ - file://71-weston-drm.rules \ + file://weston.service \ + file://weston.socket \ file://weston-autologin \ file://weston-start" @@ -36,17 +35,15 @@ do_install() { install -Dm644 ${WORKDIR}/weston.env ${D}${sysconfdir}/default/weston # Install Weston systemd service and accompanying udev rule - install -D -p -m0644 ${WORKDIR}/weston@.service ${D}${systemd_system_unitdir}/weston@.service - install -D -p -m0644 ${WORKDIR}/weston@.socket ${D}${systemd_system_unitdir}/weston@.socket + install -D -p -m0644 ${WORKDIR}/weston.service ${D}${systemd_system_unitdir}/weston.service + install -D -p -m0644 ${WORKDIR}/weston.socket ${D}${systemd_system_unitdir}/weston.socket if [ "${@bb.utils.filter('DISTRO_FEATURES', 'pam', d)}" ]; then install -D -p -m0644 ${WORKDIR}/weston-autologin ${D}${sysconfdir}/pam.d/weston-autologin fi sed -i -e s:/etc:${sysconfdir}:g \ -e s:/usr/bin:${bindir}:g \ -e s:/var:${localstatedir}:g \ - ${D}${systemd_unitdir}/system/weston@.service - install -D -p -m0644 ${WORKDIR}/71-weston-drm.rules \ - ${D}${sysconfdir}/udev/rules.d/71-weston-drm.rules + ${D}${systemd_unitdir}/system/weston.service # Install weston-start script install -Dm755 ${WORKDIR}/weston-start ${D}${bindir}/weston-start sed -i 's,@DATADIR@,${datadir},g' ${D}${bindir}/weston-start @@ -58,11 +55,15 @@ do_install() { if [ "${@bb.utils.contains('PACKAGECONFIG', 'no-idle-timeout', 'yes', 'no', d)}" = "yes" ]; then sed -i -e "/^\[core\]/a idle-time=0" ${D}${sysconfdir}/xdg/weston/weston.ini fi + + install -dm 755 -o weston -g weston ${D}/home/weston } INHIBIT_UPDATERCD_BBCLASS = "${@oe.utils.conditional('VIRTUAL-RUNTIME_init_manager', 'systemd', '1', '', d)}" -inherit update-rc.d features_check systemd +inherit update-rc.d features_check systemd useradd + +USERADD_PACKAGES = "${PN}" # rdepends on weston which depends on virtual/egl # requires pam enabled if started via systemd @@ -73,10 +74,18 @@ RDEPENDS_${PN} = "weston kbd" INITSCRIPT_NAME = "weston" INITSCRIPT_PARAMS = "start 9 5 2 . stop 20 0 1 6 ." -FILES_${PN} += "${sysconfdir}/xdg/weston/weston.ini ${systemd_system_unitdir}/weston@.service ${systemd_system_unitdir}/weston@.socket ${sysconfdir}/default/weston ${sysconfdir}/pam.d/" +FILES_${PN} += "\ + ${sysconfdir}/xdg/weston/weston.ini \ + ${systemd_system_unitdir}/weston.service \ + ${systemd_system_unitdir}/weston.socket \ + ${sysconfdir}/default/weston \ + ${sysconfdir}/pam.d/ \ + /home/weston \ + " CONFFILES_${PN} += "${sysconfdir}/xdg/weston/weston.ini ${sysconfdir}/default/weston" -SYSTEMD_SERVICE_${PN} = "weston@%i.service" -SYSTEMD_AUTO_ENABLE = "disable" +SYSTEMD_SERVICE_${PN} = "weston.service weston.socket" +USERADD_PARAM_${PN} = "--home /home/weston --shell /bin/sh --user-group -G video,input weston" +GROUPADD_PARAM_${PN} = "-r wayland" diff --git a/meta/recipes-graphics/wayland/weston-init/71-weston-drm.rules b/meta/recipes-graphics/wayland/weston-init/71-weston-drm.rules deleted file mode 100644 index 1a1b8bbda4..0000000000 --- a/meta/recipes-graphics/wayland/weston-init/71-weston-drm.rules +++ /dev/null @@ -1,2 +0,0 @@ -ACTION=="add", SUBSYSTEM=="graphics", KERNEL=="fb0", TAG+="systemd", ENV{SYSTEMD_WANTS}+="weston@root.service" -ACTION=="add", SUBSYSTEM=="drm", KERNEL=="card0", TAG+="systemd", ENV{SYSTEMD_WANTS}+="weston@root.service" diff --git a/meta/recipes-graphics/wayland/weston-init/weston@.service b/meta/recipes-graphics/wayland/weston-init/weston.service similarity index 83% rename from meta/recipes-graphics/wayland/weston-init/weston@.service rename to meta/recipes-graphics/wayland/weston-init/weston.service index ce8f4fb71a..e09625b31c 100644 --- a/meta/recipes-graphics/wayland/weston-init/weston@.service +++ b/meta/recipes-graphics/wayland/weston-init/weston.service @@ -9,6 +9,7 @@ Documentation=man:weston(1) man:weston.ini(5) Documentation=http://wayland.freedesktop.org/ # Make sure we are started after logins are permitted. +Requires=systemd-user-sessions.service After=systemd-user-sessions.service # If Plymouth is used, we want to start when it is on its way out. @@ -18,6 +19,9 @@ After=plymouth-quit-wait.service Wants=dbus.socket After=dbus.socket +# Ensure the socket is present +Requires=weston.socket + # Since we are part of the graphical session, make sure we are started before # it is complete. Before=graphical.target @@ -37,10 +41,11 @@ TimeoutStartSec=60 WatchdogSec=20 # The user to run Weston as. -User=%I +User=weston +Group=weston -# Make sure working directory is users home directory -WorkingDirectory=/home/%i +# Make sure the working directory is the users home directory +WorkingDirectory=/home/weston # Set up a full user session for the user, required by Weston. PAMName=weston-autologin @@ -61,5 +66,6 @@ UtmpIdentifier=tty7 UtmpMode=user [Install] +# Note: If you only want weston to start on-demand, remove this line with a +# service drop file WantedBy=graphical.target -DefaultInstance=tty7 diff --git a/meta/recipes-graphics/wayland/weston-init/weston.socket b/meta/recipes-graphics/wayland/weston-init/weston.socket new file mode 100644 index 0000000000..c1bdc83c05 --- /dev/null +++ b/meta/recipes-graphics/wayland/weston-init/weston.socket @@ -0,0 +1,14 @@ +[Unit] +Description=Weston socket +RequiresMountsFor=/run + +[Socket] +ListenStream=/run/wayland-0 +SocketMode=0775 +SocketUser=weston +SocketGroup=wayland +RemoveOnStop=yes + +[Install] +WantedBy=sockets.target + diff --git a/meta/recipes-graphics/wayland/weston-init/weston@.socket b/meta/recipes-graphics/wayland/weston-init/weston@.socket deleted file mode 100644 index f1790d74a8..0000000000 --- a/meta/recipes-graphics/wayland/weston-init/weston@.socket +++ /dev/null @@ -1,10 +0,0 @@ -[Unit] -Description=Weston Wayland socket -After=user-runtime-dir@1000.service - -[Socket] -ListenStream=/run/user/1000/wayland-%I - -[Install] -WantedBy=sockets.target -