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Systemd unit is unsafe #210
Description
The Systemd unit at https://github.com/cjdelisle/cjdns/blob/master/contrib/systemd/cjdns.service seems to be quite insecure. Is it possible to improve this?
NAME DESCRIPTION EXPOSURE
✗ PrivateNetwork= Service has access to the host's network 0.5
✗ User=/DynamicUser= Service runs as root user 0.4
✗ CapabilityBoundingSet=~CAP_SET(UID|GID|PCAP) Service may change UID/GID identities/capabilities 0.3
✗ CapabilityBoundingSet=~CAP_SYS_ADMIN Service has administrator privileges 0.3
✗ CapabilityBoundingSet=~CAP_SYS_PTRACE Service has ptrace() debugging abilities 0.3
✗ RestrictAddressFamilies=~AF_(INET|INET6) Service may allocate Internet sockets 0.3
✗ RestrictNamespaces=~CLONE_NEWUSER Service may create user namespaces 0.3
✗ RestrictAddressFamilies=~… Service may allocate exotic sockets 0.3
✗ CapabilityBoundingSet=~CAP_(CHOWN|FSETID|SETFCAP) Service may change file ownership/access mode/capabilities unrestricted 0.2
✗ CapabilityBoundingSet=~CAP_(DAC_*|FOWNER|IPC_OWNER) Service may override UNIX file/IPC permission checks 0.2
✗ CapabilityBoundingSet=~CAP_NET_ADMIN Service has network configuration privileges 0.2
✗ CapabilityBoundingSet=~CAP_SYS_MODULE Service may load kernel modules 0.2
✗ CapabilityBoundingSet=~CAP_SYS_RAWIO Service has raw I/O access 0.2
✗ CapabilityBoundingSet=~CAP_SYS_TIME Service processes may change the system clock 0.2
✗ DeviceAllow= Service has no device ACL 0.2
✗ IPAddressDeny= Service does not define an IP address allow list 0.2
✓ KeyringMode= Service doesn't share key material with other services
✗ NoNewPrivileges= Service processes may acquire new privileges 0.2
✓ NotifyAccess= Service child processes cannot alter service state
✗ PrivateDevices= Service potentially has access to hardware devices 0.2
✓ PrivateMounts= Service cannot install system mounts
✗ PrivateTmp= Service has access to other software's temporary files 0.2
✗ PrivateUsers= Service has access to other users 0.2
✗ ProtectClock= Service may write to the hardware clock or system clock 0.2
✗ ProtectControlGroups= Service may modify the control group file system 0.2
✓ ProtectHome= Service has no access to home directories
✗ ProtectKernelLogs= Service may read from or write to the kernel log ring buffer 0.2
✗ ProtectKernelModules= Service may load or read kernel modules 0.2
✗ ProtectKernelTunables= Service may alter kernel tunables 0.2
✗ ProtectProc= Service has full access to process tree (/proc hidepid=) 0.2
✗ ProtectSystem= Service has limited write access to the OS file hierarchy 0.1
✗ RestrictAddressFamilies=~AF_PACKET Service may allocate packet sockets 0.2
✗ RestrictSUIDSGID= Service may create SUID/SGID files 0.2
✗ SystemCallArchitectures= Service may execute system calls with all ABIs 0.2
✗ SystemCallFilter=~@clock Service does not filter system calls 0.2
✗ SystemCallFilter=~@debug Service does not filter system calls 0.2
✗ SystemCallFilter=~@module Service does not filter system calls 0.2
✗ SystemCallFilter=~@mount Service does not filter system calls 0.2
✗ SystemCallFilter=~@raw-io Service does not filter system calls 0.2
✗ SystemCallFilter=~@reboot Service does not filter system calls 0.2
✗ SystemCallFilter=~@swap Service does not filter system calls 0.2
✗ SystemCallFilter=~@privileged Service does not filter system calls 0.2
✗ SystemCallFilter=~@resources Service does not filter system calls 0.2
✓ AmbientCapabilities= Service process does not receive ambient capabilities
✗ CapabilityBoundingSet=~CAP_AUDIT_* Service has audit subsystem access 0.1
✗ CapabilityBoundingSet=~CAP_KILL Service may send UNIX signals to arbitrary processes 0.1
✗ CapabilityBoundingSet=~CAP_MKNOD Service may create device nodes 0.1
✗ CapabilityBoundingSet=~CAP_NET_(BIND_SERVICE|BROADCAST|RAW) Service has elevated networking privileges 0.1
✗ CapabilityBoundingSet=~CAP_SYSLOG Service has access to kernel logging 0.1
✗ CapabilityBoundingSet=~CAP_SYS_(NICE|RESOURCE) Service has privileges to change resource use parameters 0.1
✗ RestrictNamespaces=~CLONE_NEWCGROUP Service may create cgroup namespaces 0.1
✗ RestrictNamespaces=~CLONE_NEWIPC Service may create IPC namespaces 0.1
✗ RestrictNamespaces=~CLONE_NEWNET Service may create network namespaces 0.1
✗ RestrictNamespaces=~CLONE_NEWNS Service may create file system namespaces 0.1
✗ RestrictNamespaces=~CLONE_NEWPID Service may create process namespaces 0.1
✗ RestrictRealtime= Service may acquire realtime scheduling 0.1
✗ SystemCallFilter=~@cpu-emulation Service does not filter system calls 0.1
✗ SystemCallFilter=~@obsolete Service does not filter system calls 0.1
✗ RestrictAddressFamilies=~AF_NETLINK Service may allocate netlink sockets 0.1
✗ RootDirectory=/RootImage= Service runs within the host's root directory 0.1
SupplementaryGroups= Service runs as root, option does not matter
✗ CapabilityBoundingSet=~CAP_MAC_* Service may adjust SMACK MAC 0.1
✗ CapabilityBoundingSet=~CAP_SYS_BOOT Service may issue reboot() 0.1
✓ Delegate= Service does not maintain its own delegated control group subtree
✗ LockPersonality= Service may change ABI personality 0.1
✗ MemoryDenyWriteExecute= Service may create writable executable memory mappings 0.1
RemoveIPC= Service runs as root, option does not apply
✗ RestrictNamespaces=~CLONE_NEWUTS Service may create hostname namespaces 0.1
✗ UMask= Files created by service are world-readable by default 0.1
✗ CapabilityBoundingSet=~CAP_LINUX_IMMUTABLE Service may mark files immutable 0.1
✗ CapabilityBoundingSet=~CAP_IPC_LOCK Service may lock memory into RAM 0.1
✗ CapabilityBoundingSet=~CAP_SYS_CHROOT Service may issue chroot() 0.1
✗ ProtectHostname= Service may change system host/domainname 0.1
✗ CapabilityBoundingSet=~CAP_BLOCK_SUSPEND Service may establish wake locks 0.1
✗ CapabilityBoundingSet=~CAP_LEASE Service may create file leases 0.1
✗ CapabilityBoundingSet=~CAP_SYS_PACCT Service may use acct() 0.1
✗ CapabilityBoundingSet=~CAP_SYS_TTY_CONFIG Service may issue vhangup() 0.1
✗ CapabilityBoundingSet=~CAP_WAKE_ALARM Service may program timers that wake up the system 0.1
✗ RestrictAddressFamilies=~AF_UNIX Service may allocate local sockets 0.1
✗ ProcSubset= Service has full access to non-process /proc files (/proc subset=) 0.1
→ Overall exposure level for cjdns.service: 9.1 UNSAFE 😨
Activity
marek22k commentedon Oct 22, 2023
Ping on maintainer: @kpcyrd @cjdelisle
progval commentedon Oct 23, 2023
Most of this is unnecessary because cjdns uses SECCOMP to drop privileges after startup; don't rely blindly on what systemd-analyze tells you.
Regardless, have you tried sending a PR to add these restrictions to the systemd unit?
marek22k commentedon Nov 18, 2025
https://github.com/cjdelisle/cjdns/blob/master/CHANGELOG.md
seems seccomp is gone
cjdelisle commentedon Dec 5, 2025
Yes, internal seccomp is gone, because it became a big hassle to maintain. It was a whitelist and it had to consider different architectures and libc implementations which use different syscalls - then to top it off, Rust can surprise you with what syscalls it ends up using. This systemd script is not part of cjdns proper, but if you want to improve it, I would recommend removing some items which are obviously not needed (like reboot) and testing. It needs CAP_NET_ADMIN for setting IP addresses and routes, it needs setuid and chroot for self-sandboxing, and it (unfortunately) needs to spawn processes - but it doesn't need FS access (except beware some Rust library code might create a temp file from time to time)