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This change introduces the nointernet() function which may be called to prevent a process and its descendants from communicating with publicly routable Internet addresses. GNU Make has been modified to always call this function. In the future Landlock Make will have a way to whitelist subnets to override this behavior, or disable it entirely. Support is available for Linux only. Our firewall does not require root access. Calling nointernet() will return control to the caller inside a new process that has a SECCOMP BPF filter installed, which traps network related system calls. Your original process then becomes a permanent ptrace() supervisor that monitors all processes and threads descending from the returned child. Whenever a networking system call happens the kernel will stop the process and wakes up the monitor, which then peeks into the child memory to read the sockaddr_in to determine if it's ok. The downside to doing this is that there can be only one supervisor at a time using ptrace() on a process. So this firewall won't be enabled if you run make under strace or inside gdb. It also makes testing tricky. |
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| .. | ||
| dsp | ||
| libc | ||
| net | ||
| tool | ||
| test.mk | ||