Seccomp is a linux kernel feature that allows a process a one-way transition into secure mode, where restrictions are applied to the syscalls the process can make, as well as restrictions on the file descriptors. Specifically, it can exit, sigreturn and read/write already open file descriptors. This way the process can be isolated and restricted on how it interacts with rest of the system on a kernel level.
This crate does not actually implement any particular feature, but provides Rust FFI bindings for seccomp module. These are primarily generated by using rsut-bindgen on seccomp C header file, and then manually fixed where any issues were found. More information about seccomp can be found in its man page.