[arch-general] matrix-synapse "enhanced" security
Dear all, beginning with matrix-synapse 1.44.0-1 in early October a Systemd override file (see below for reference) was included to the package that aims to enhance the security of Synapse. Amongst other things it tells Systemd to restrict access to certain directories that are seen as defaults. Unfortunately this enhancement broke my setup by neglecting that there are various paths inside Synapse's configuration that can be customized, e.g. media_store_path and uploads_path. The error I see in my logs is: 2021-11-18 19:54:30,772 - synapse.rest.media.v1.preview_url_resource - 559 - WARNING - expire_url_cache_data-1281 - Failed to remove media directory: '/srv/matrix/media_store/url_cache/2021-10-08': [Errno 30] Read-only file system: '/srv/matrix/media_store/url_cache/2021-10-08' 2021-11-18 19:54:30,774 - synapse.rest.media.v1.preview_url_resource - 617 - WARNING - expire_url_cache_data-1281 - Failed to remove media: '2021-10-08_cgWYZUYMTRBdzskW': [Errno 30] Read-only file system: '800-450-image-jpeg-scale' It is also impossible to insert pictures into the chat. The client just tells "unable to send message" but no log entry is created on the server. Did I miss any notification about this change? Can anyone help me with customizing the Systemd override file so that Synapse regains access to media_store_path and uploads_path? Any help is appreciated. Thank you, Uwe ### /usr/lib/systemd/system/synapse.service.d/override-hardened.conf ### [Service] # The following directives give the synapse service R/W access to: # - /run/synapse # - /var/lib/synapse # - /var/log/synapse RuntimeDirectory=synapse StateDirectory=synapse LogsDirectory=synapse ###################### ## Security Sandbox ## ###################### # Make sure that the service has its own unshared tmpfs at /tmp and that it # cannot see or change any real devices PrivateTmp=true PrivateDevices=true # We give no capabilities to a service by default CapabilityBoundingSet= AmbientCapabilities= # Protect the following from modification: # - The entire filesystem # - sysctl settings and loaded kernel modules # - No modifications allowed to Control Groups # - Hostname # - System Clock ProtectSystem=strict ProtectKernelTunables=true ProtectKernelModules=true ProtectControlGroups=true ProtectClock=true ProtectHostname=true # Prevent access to the following: # - /home directory # - Kernel logs ProtectHome=tmpfs ProtectKernelLogs=true # Make sure that the process can only see PIDs and process details of itself, # and the second option disables seeing details of things like system load and # I/O etc ProtectProc=invisible ProcSubset=pid # While not needed, we set these options explicitly # - This process has been given access to the host network # - It can also communicate with any IP Address PrivateNetwork=false RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX IPAddressAllow=any # Restrict system calls to a sane bunch SystemCallArchitectures=native SystemCallFilter=@system-service SystemCallFilter=~@privileged @resources @obsolete # Misc restrictions # - Since the process is a python process it needs to be able to write and # execute memory regions, so we set MemoryDenyWriteExecute to false RestrictSUIDSGID=true RemoveIPC=true NoNewPrivileges=true RestrictRealtime=true RestrictNamespaces=true LockPersonality=true PrivateUsers=true MemoryDenyWriteExecute=false ### EOF ###
Hi,
First time responding here, if anything is not as it should please tell me.
I guess you should get it to work by creating a new drop-in file with
ReadWritePaths= set to the list of directories you want synapse to have
access to.
May consult the man page of systemd.exec for more information about that.
Best regards
Patrick
Uwe Sauter via arch-general
Dear all,
beginning with matrix-synapse 1.44.0-1 in early October a Systemd override file (see below for reference) was included to the package that aims to enhance the security of Synapse. Amongst other things it tells Systemd to restrict access to certain directories that are seen as defaults.
Unfortunately this enhancement broke my setup by neglecting that there are various paths inside Synapse's configuration that can be customized, e.g. media_store_path and uploads_path. The error I see in my logs is:
2021-11-18 19:54:30,772 - synapse.rest.media.v1.preview_url_resource - 559 - WARNING - expire_url_cache_data-1281 - Failed to remove media directory: '/srv/matrix/media_store/url_cache/2021-10-08': [Errno 30] Read-only file system: '/srv/matrix/media_store/url_cache/2021-10-08' 2021-11-18 19:54:30,774 - synapse.rest.media.v1.preview_url_resource - 617 - WARNING - expire_url_cache_data-1281 - Failed to remove media: '2021-10-08_cgWYZUYMTRBdzskW': [Errno 30] Read-only file system: '800-450-image-jpeg-scale'
It is also impossible to insert pictures into the chat. The client just tells "unable to send message" but no log entry is created on the server.
Did I miss any notification about this change?
Can anyone help me with customizing the Systemd override file so that Synapse regains access to media_store_path and uploads_path?
Any help is appreciated.
Thank you,
Uwe
### /usr/lib/systemd/system/synapse.service.d/override-hardened.conf ### [Service] # The following directives give the synapse service R/W access to: # - /run/synapse # - /var/lib/synapse # - /var/log/synapse
RuntimeDirectory=synapse StateDirectory=synapse LogsDirectory=synapse
###################### ## Security Sandbox ## ######################
# Make sure that the service has its own unshared tmpfs at /tmp and that it # cannot see or change any real devices PrivateTmp=true PrivateDevices=true
# We give no capabilities to a service by default CapabilityBoundingSet= AmbientCapabilities=
# Protect the following from modification: # - The entire filesystem # - sysctl settings and loaded kernel modules # - No modifications allowed to Control Groups # - Hostname # - System Clock ProtectSystem=strict ProtectKernelTunables=true ProtectKernelModules=true ProtectControlGroups=true ProtectClock=true ProtectHostname=true
# Prevent access to the following: # - /home directory # - Kernel logs ProtectHome=tmpfs ProtectKernelLogs=true
# Make sure that the process can only see PIDs and process details of itself, # and the second option disables seeing details of things like system load and # I/O etc ProtectProc=invisible ProcSubset=pid
# While not needed, we set these options explicitly # - This process has been given access to the host network # - It can also communicate with any IP Address PrivateNetwork=false RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX IPAddressAllow=any
# Restrict system calls to a sane bunch SystemCallArchitectures=native SystemCallFilter=@system-service SystemCallFilter=~@privileged @resources @obsolete
# Misc restrictions # - Since the process is a python process it needs to be able to write and # execute memory regions, so we set MemoryDenyWriteExecute to false RestrictSUIDSGID=true RemoveIPC=true NoNewPrivileges=true RestrictRealtime=true RestrictNamespaces=true LockPersonality=true PrivateUsers=true MemoryDenyWriteExecute=false ### EOF ###
On Thu, Nov 18, 2021 at 08:02:23PM +0100, Uwe Sauter via arch-general wrote:
Dear all,
hello Uwe.
beginning with matrix-synapse 1.44.0-1 in early October a Systemd override file (see below for reference) was included to the package that aims to enhance the security of Synapse. Amongst other things it tells Systemd to restrict access to certain directories that are seen as defaults.
yep. I did this.
Unfortunately this enhancement broke my setup by neglecting that there are various paths inside Synapse's configuration that can be customized, e.g. media_store_path and uploads_path. The error I see in my logs is:
sorry for that.
It is also impossible to insert pictures into the chat. The client just tells "unable to send message" but no log entry is created on the server.
Did I miss any notification about this change?
there are no notification about that. and I am sorry for that too.
Can anyone help me with customizing the Systemd override file so that Synapse regains access to media_store_path and uploads_path?
Certainly. you can edit the synapse.service unit with the systemctl edit command and write ReadWritePaths=/srv/matrix in the [Service] section you can read about systemd unit editing on the arch wiki[1] and consult systemd.exec man[2] for more information about unit restrictions.
Any help is appreciated.
Thank you,
Uwe
[1]: https://wiki.archlinux.org/title/Systemd#Editing_provided_units [2]: https://man.archlinux.org/man/systemd.exec.5#SANDBOXING -- Sincerely, Alexander | Trusted User
Hello Alexander, hello Patrick, thanks for your suggestions, they seem to work. @Alexander: Would you mind adding this customization to the wiki article about Matrix/Synapse [1]? There is already a section regarding the read-only error but no work-around/solution yet. Also, please accept my gratitude for your work maintaining the matrix-synapse package. Thank you both, Uwe [1] https://wiki.archlinux.org/title/Matrix Am 18.11.21 um 23:53 schrieb Alexander Epaneshnikov:
On Thu, Nov 18, 2021 at 08:02:23PM +0100, Uwe Sauter via arch-general wrote:
Dear all,
hello Uwe.
beginning with matrix-synapse 1.44.0-1 in early October a Systemd override file (see below for reference) was included to the package that aims to enhance the security of Synapse. Amongst other things it tells Systemd to restrict access to certain directories that are seen as defaults.
yep. I did this.
Unfortunately this enhancement broke my setup by neglecting that there are various paths inside Synapse's configuration that can be customized, e.g. media_store_path and uploads_path. The error I see in my logs is:
sorry for that.
It is also impossible to insert pictures into the chat. The client just tells "unable to send message" but no log entry is created on the server.
Did I miss any notification about this change?
there are no notification about that. and I am sorry for that too.
Can anyone help me with customizing the Systemd override file so that Synapse regains access to media_store_path and uploads_path?
Certainly. you can edit the synapse.service unit with the systemctl edit command and write ReadWritePaths=/srv/matrix in the [Service] section
you can read about systemd unit editing on the arch wiki[1] and consult systemd.exec man[2] for more information about unit restrictions.
Any help is appreciated.
Thank you,
Uwe
[1]: https://wiki.archlinux.org/title/Systemd#Editing_provided_units [2]: https://man.archlinux.org/man/systemd.exec.5#SANDBOXING
-- Sincerely, Alexander | Trusted User
On Fri, Nov 19, 2021 at 12:00:09AM +0100, Uwe Sauter wrote:
Hello Alexander, hello Patrick,
thanks for your suggestions, they seem to work.
glad to hear that.
@Alexander: Would you mind adding this customization to the wiki article about Matrix/Synapse [1]? There is already a section regarding the read-only error but no work-around/solution yet. Also, please accept my gratitude for your work maintaining the matrix-synapse package.
done.
Thank you both,
Uwe
-- Sincerely, Alexander | Trusted User
participants (3)
-
Alexander Epaneshnikov
-
Patrick Pacher
-
Uwe Sauter