In unprivileged podman containers, /proc is not fully visible (there
are other filesystems mounted on subdirectories of /proc). Therefore
we can't mount a new /proc in the sandbox that matches the PID
namespace of the sandbox. So this commit automatically disables
sandboxing if /proc is not fully visible.
This didn't work because sandboxing doesn't work in Docker. However,
the sandboxing check is done lazily - after clone(CLONE_NEWNS) fails,
we retry with sandboxing disabled. But at that point, we've already
done UID allocation under the assumption that user namespaces are
enabled.
So let's get rid of the "goto fallback" logic and just detect early
whether user / mount namespaces are enabled.
This commit also gets rid of a compatibility hack for some ancient
Linux kernels (<2.13).
Previously we would completely refetch the submodules from the
network, even though the repo might already have them. Now we copy the
.git/modules directory from the repo as an optimisation. This speeds
up evaluating
builtins.fetchTree { type = "git"; url = "/path/to/blender"; submodules = true; }
(where /path/to/blender already has the needed submodules) from 121s
to 57s.
This is still pretty inefficient and a hack, but a better solution is
best done on the lazy-trees branch.
This change also help in the case where the repo already has the
submodules but the origin is unfetchable for whatever reason
(e.g. there have been cases where Nix in a GitHub action doesn't have
the right authentication set up).
We cannot use 'actualUrl', because for file:// repos that's not the
original URL that the repo was fetched from. This is a problem since
submodules may be relative to the original URL.
Fixes e.g.
nix eval --impure --json --expr 'builtins.fetchTree { type = "git"; url = "/path/to/blender"; submodules = true; }'
where /path/to/blender is a clone of
https://github.com/blender/blender.git (which has several relative
submodules like '../blender-addons.git').
`clang11StdenvPackages` does not exist
```
│ └───x86_64-linux
│ ├───ccacheStdenv: development environment 'nix'
│ ├───clang11Stdenv: development environment 'nix'
│ ├───clangStdenv: development environment 'nix'
│ ├───default: development environment 'nix'
│ ├───gccStdenv: development environment 'nix'
│ ├───libcxxStdenv: development environment 'nix'
│ └───stdenv: development environment 'nix'
```
Per the old FIXME, this flag was on too many commands, and mostly
ignored. Now it is just on the commands where it actually has an effect.
Per https://github.com/NixOS/nix/issues/7261, I would still like to get
rid of it entirely, but that is a separate project. This change should
be good with or without doing that.
tl;dr: With this 1 line change I was able to get a speedup of 1.5x on 1Gbit/s
wan connections by enabling zstd compression in nginx.
Also nix already supported all common compression format for http
transfer, webservers usually only enable them if they are advertised
through the Accept-Encoding header.
This pull requests makes nix advertises content compression support for
zstd, br, gzip and deflate.
It's particular useful to add transparent compression for binary caches
that serve packages from the host nix store in particular nix-serve,
nix-serve-ng and harmonia.
I tried so far gzip, brotli and zstd, whereas only zstd was able to bring
me performance improvements for 1Gbit/s WAN connections.
The following nginx configuration was used in combination with the
[zstd module](https://github.com/tokers/zstd-nginx-module) and
[harmonia](https://github.com/nix-community/harmonia/)
```nix
{
services.nginx.virtualHosts."cache.yourhost.com" = {
locations."/".extraConfig = ''
proxy_pass http://127.0.0.1:5000;
proxy_set_header Host $host;
proxy_redirect http:// https://;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;
zstd on;
zstd_types application/x-nix-archive;
'';
};
}
```
For testing I unpacked a linux kernel tarball to the nix store using
this command `nix-prefetch-url --unpack https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.1.8.tar.gz`.
Before:
```console
$ nix build && rm -rf /tmp/hello && time ./result/bin/nix copy --no-check-sigs --from https://cache.thalheim.io --to 'file:///tmp/hello?compression=none' '/nix/store/j42mahch5f0jvfmayhzwbb88sw36fvah-linux-6.1.8.tar.gz'
warning: Git tree '/scratch/joerg/nix' is dirty
real 0m18,375s
user 0m2,889s
sys 0m1,558s
```
After:
```console
$ nix build && rm -rf /tmp/hello && time ./result/bin/nix copy --no-check-sigs --from https://cache.thalheim.io --to 'file:///tmp/hello?compression=none' '/nix/store/j42mahch5f0jvfmayhzwb
b88sw36fvah-linux-6.1.8.tar.gz'
real 0m11,884s
user 0m4,130s
sys 0m1,439s
```
Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
Update src/libstore/filetransfer.cc
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
These settings are not needed for libstore at all, they are just used by
the nix daemon *command* for authorization on unix domain sockets. My
moving them to a new configuration struct just in that file, we avoid
them leaking anywhere else.
Also, it is good to break up the mammoth `Settings` struct in general.
Issue #5638 tracks this.
The message is not changed because I do not want to regress in
convenience to the user. Just saying "this connection is not trusted"
doesn't tell them out to fix the issue. The ideal thing to do would be
to somehow parameterize `processCommand` on how the error should be
displayed, so different sorts of connections can display different
information to the user based on how authentication is performed for the
connection in question. This, however, is a good bit more work, so it is
left for the future.
This came up with me thinking about the tcp:// store (#5265). The larger
project is not TCP *per se*, but the idea that it should be possible for
something else to manage access control to services like the Nix Daemon,
and those services simply trust or trust the incoming connection as they
are told. This is a more capability-oriented way of thinking about trust
than "every server implements its own auth separately" as we are used to today.
Its very great that libstore itself already implements just this model,
and so via this refactor I basically want to "enshrine" that so it
continues to be the case.
Robert Hensing
Jörg Thalheim