This eliminates a theoretical risk of ASLR bypass due to the fixed address
mapping used by the legacy vsyscall mechanism. Modern glibc use vdso(7)
instead so there is no loss of functionality, but some programs may fail
to run in this configuration. Programs that fail to run because vsyscall
has been disabled will be logged to dmesg.
For background on virtual syscalls see https://lwn.net/Articles/446528/
Closes https://github.com/NixOS/nixpkgs/pull/25289
The idea is to provide a convenient way to enable most vanilla hardening
features in one go. The hardened profile, then, will serve as a place for
features that enhance security but cannot be enabled for all deployments
because they interfere with legitimate use cases (e.g., using ptrace to
debug problems in an already running process).
Closes https://github.com/NixOS/nixpkgs/pull/24680
