This patch replaces the old grsecurity kernels with a single NixOS
specific grsecurity kernel. This kernel is intended as a general
purpose kernel, tuned for casual desktop use.
Providing only a single kernel may seem like a regression compared to
offering a multitude of flavors. It is impossible, however, to
effectively test and support that many options. This is amplified by
the reality that very few seem to actually use grsecurity on NixOS,
meaning that bugs go unnoticed for long periods of time, simply because
those code paths end up never being exercised. More generally, it is
hopeless to anticipate imagined needs. It is better to start from a
solid foundation and possibly add more flavours on demand.
While the generic kernel is intended to cover a wide range of use cases,
it cannot cover everything. For some, the configuration will be either
too restrictive or too lenient. In those cases, the recommended
solution is to build a custom kernel --- this is *strongly* recommended
for security sensitive deployments.
Building a custom grsec kernel should be as simple as
```nix
linux_grsec_nixos.override {
extraConfig = ''
GRKERNSEC y
PAX y
# and so on ...
'';
}
```
The generic kernel should be usable both as a KVM guest and host. When
running as a host, the kernel assumes hardware virtualisation support.
Virtualisation systems other than KVM are *unsupported*: users of
non-KVM systems are better served by compiling a custom kernel.
Unlike previous Grsecurity kernels, this configuration disables `/proc`
restrictions in favor of `security.hideProcessInformation`.
Known incompatibilities:
- ZFS: can't load spl and zfs kernel modules; claims incompatibility
with KERNEXEC method `or` and RAP; changing to `bts` does not fix the
problem, which implies we'd have to disable RAP as well for ZFS to
work
- `kexec()`: likely incompatible with KERNEXEC (unverified)
- Xen: likely incompatible with KERNEXEC and UDEREF (unverified)
- Virtualbox: likely incompatible with UDEREF (unverified)
This takes another approach at binding FHS directory structure. We
now bind-mount all the root filesystem to directory "/host" in the target tree.
From that we symlink all the directories into the tree if they do not already
exist in FHS structure.
This probably makes `CHROOTENV_EXTRA_BINDS` unnecessary -- its main usecase was
to add bound directories from the host to the sandbox, and we not just symlink
all of them. I plan to get some feedback on its usage and maybe deprecate it.
This also drops old `buildFHSChrootEnv` infrastructure. The main problem with it
is it's very difficult to unmount a recursive-bound directory when mount is not
sandboxed. This problem is a bug even without these changes -- if
you have for example `/home/alice` mounted to somewhere, you wouldn't see
it in `buildFHSChrootEnv` now. With the new directory structure, it's
impossible to use regular bind at all. After some tackling with this I realized
that the fix would be brittle and dangerous (if you don't unmount everything
clearly and proceed to removing the temporary directory, bye-bye fs!). It also
probably doesn't worth it because I haven't heard that someone actually uses it
for a long time, and `buildFHSUserEnv` should cover most cases while being much
more maintainable and safe for the end-user.
1. When multiple versions of the same package are required
$revs is an array.
2. When cargo fetch is run it usually doesn't need a network
connection. But when it does SSL_CERT_FILE isn't set.
find fails when called with an inexistent search path.
That situation may arise when the output is created after by a postFixup hook.
vcunat amended the PR by clarifying one more `return` to `return 0`.
Checkinstall had two problems:
1. when it was called without a version (e.g. with a derivation created
by fetchFromGitHub) it would use `src` as debian version, which caused
dpkg to fail
2. when dpkg failed, it would invoke the pager with the log, which hangs
the build
So now
1. the default version is the dummy `0.0.0`
2. the used pager is `cat`
Source of this change goes back to 2009 and original version of
fetchgit at 205fb0c87e.
The nondeterminism is really caused by changing .git so leave other
files alone as they might be interesting.
Note: this causes a hash mismatch with Hydra's version of Git Plugin
which we should fix to comply.
Move all the dependencies to their own derivation, so that we don't publish all
of them if the wrapper is installed in a profile.
The previous solution just moved them to a custom directory to avoid conflicts,
this refactors that and completely hides them, while preserving the desired
improvement of adding only one directory to each of the emacs search paths
The chroot caps restriction disallows chroot'ed processes from running
any command that requires `CAP_SYS_ADMIN`, breaking `nixos-rebuild`. See
e.g., https://github.com/NixOS/nixpkgs/issues/15293
This significantly weakens chroot protections, but to break
nixos-rebuild out of the box is too severe.
