The workaround for "Some distros patch Linux" mentioned in
local-derivation-goal.cc will not help in the `--option
sandbox-fallback false` case. To provide the user more helpful
guidance on how to get the sandbox working, let's check to see if the
`/proc` node created by the aforementioned patch is present and
configured in a way that will cause us problems. If so, give the user
a suggestion for how to troubleshoot the problem.
local-derivation-goal.cc contains a comment stating that "Some distros
patch Linux to not allow unprivileged user namespaces." Let's give a
pointer to a common version of this patch for those who want more
details about this failure mode.
This commit causes nix to `warn()` if sandbox setup has failed and
`/proc/self/ns/user` does not exist. This is usually a sign that the
kernel was compiled without `CONFIG_USER_NS=y`, which is required for
sandboxing.
This commit uses `warn()` to notify the user if sandbox setup fails
with errno==EPERM and /proc/sys/user/max_user_namespaces is missing or
zero, since that is at least part of the reason why sandbox setup
failed.
Note that `echo -n 0 > /proc/sys/user/max_user_namespaces` or
equivalent at boot time has been the recommended mitigation for
several Linux LPE vulnerabilities over the past few years. Many users
have applied this mitigation and then forgotten that they have done
so.
The failure modes for nix's sandboxing setup are pretty complicated.
When nix is unable to set up the sandbox, let's provide more detail
about what went wrong. Specifically:
* Make sure the error message includes the word "sandbox" so the user
knows that the failure was related to sandboxing.
* If `--option sandbox-fallback false` was provided, and removing it
would have allowed further attempts to make progress, let the user
know.
With this, Nix will write a copy of the sandbox shell to /bin/sh in
the sandbox rather than bind-mounting it from the host filesystem.
This makes /bin/sh work out of the box with nix-static, i.e. you no
longer get
/nix/store/qa36xhc5gpf42l3z1a8m1lysi40l9p7s-bootstrap-stage4-stdenv-linux/setup: ./configure: /bin/sh: bad interpreter: No such file or directory
A mips64el Linux MIPS kernel can execute userspace code using any of
three ABIs:
mips64el-linux-*abin64
mips64el-linux-*abin32
mipsel-linux-*
The first of these is the native 64-bit ABI, and the only ABI with
64-bit pointers; this is sometimes called "n64". The last of these is
the old legacy 32-bit ABI, whose binaries can execute natively on
32-bit MIPS hardware; this is sometimes called "o32".
The second ABI, "n32" is essentially the 64-bit ABI with 32-bit
pointers and address space. Hardware 64-bit integer/floating
arithmetic is still allowed, as well as the much larger mips64
register set and more-efficient calling convention.
Let's enable seccomp filters for all of these. Likewise for big
endian (mips64-linux-*).
Previously it only logged the builder's path, this changes it to log the
arguments at the same log level, and the environment variables at the
vomit level.
This helped me debug https://github.com/svanderburg/node2nix/issues/75
This was caused by SubstitutionGoal not setting the errorMsg field in
its BuildResult. We now get a more descriptive message than in 2.7.0, e.g.
error: path '/nix/store/13mh...' is required, but there is no substituter that can build it
instead of the misleading (since there was no build)
error: build of '/nix/store/13mh...' failed
Fixes#6295.
Impure derivations are derivations that can produce a different result
every time they're built. Example:
stdenv.mkDerivation {
name = "impure";
__impure = true; # marks this derivation as impure
outputHashAlgo = "sha256";
outputHashMode = "recursive";
buildCommand = "date > $out";
};
Some important characteristics:
* This requires the 'impure-derivations' experimental feature.
* Impure derivations are not "cached". Thus, running "nix-build" on
the example above multiple times will cause a rebuild every time.
* They are implemented similar to CA derivations, i.e. the output is
moved to a content-addressed path in the store. The difference is
that we don't register a realisation in the Nix database.
* Pure derivations are not allowed to depend on impure derivations. In
the future fixed-output derivations will be allowed to depend on
impure derivations, thus forming an "impurity barrier" in the
dependency graph.
* When sandboxing is enabled, impure derivations can access the
network in the same way as fixed-output derivations. In relaxed
sandboxing mode, they can access the local filesystem.
This avoids an infinite loop in the final test in
tests/binary-cache.sh. I think this was only not triggered previously
by accident (because we were clearing wantedOutputs in between).
1. `DerivationOutput` now as the `std::variant` as a base class. And the
variants are given hierarchical names under `DerivationOutput`.
In 8e0d0689be @matthewbauer and I
didn't know a better idiom, and so we made it a field. But this sort
of "newtype" is anoying for literals downstream.
Since then we leaned the base class, inherit the constructors trick,
e.g. used in `DerivedPath`. Switching to use that makes this more
ergonomic, and consistent.
2. `store-api.hh` and `derivations.hh` are now independent.
In bcde5456cc I swapped the dependency,
but I now know it is better to just keep on using incomplete types as
much as possible for faster compilation and good separation of
concerns.
Continue progress on #5729.
Just as I hoped, this uncovered an issue: the daemon protocol is missing
a way to query build logs. This doesn't effect `unix://`, but does
effect `ssh://`. A FIXME is left for this, so we come back to it later.
This function is like buildPaths(), except that it returns a vector of
BuildResults containing the exact statuses and output paths of each
derivation / substitution. This is convenient for functions like
Installable::build(), because they then don't need to do another
series of calls to get the outputs of CA derivations. It's also a
precondition to impure derivations, where we *can't* query the output
of those derivations since they're not stored in the Nix database.
Note that PathSubstitutionGoal can now also return a BuildStatus.
Starts progress on #5729.
The idea is that we should not have these default methods throwing
"unimplemented". This is a small step in that direction.
I kept `addTempRoot` because it is a no-op, rather than failure. Also,
as a practical matter, it is called all over the place, while doing
other tasks, so the downcasting would be annoying.
Maybe in the future I could move the "real" `addTempRoot` to `GcStore`,
and the existing usecases use a `tryAddTempRoot` wrapper to downcast or
do nothing, but I wasn't sure whether that was a good idea so with a
bias to less churn I didn't do it yet.
To avoid that JSON messages are parsed twice in case of
remote builds with `ssh-ng://`, I split up the original
`handleJSONLogMessage` into three parts:
* `parseJSONMessage(const std::string&)` checks if it's a message in the
form of `@nix {...}` and tries to parse it (and prints an error if the
parsing fails).
* `handleJSONLogMessage(nlohmann::json&, ...)` reads the fields from the
message and passes them to the logger.
* `handleJSONLogMessage(const std::string&, ...)` behaves as before, but
uses the two functions mentioned above as implementation.
In case of `ssh-ng://`-logs the first two methods are invoked manually.
Right now when building a derivation remotely via
$ nix build -j0 -f . hello -L --builders 'ssh://builder'
it's possible later to read through the entire build-log by running
`nix log -f . hello`. This isn't possible however when using `ssh-ng`
rather than `ssh`.
The reason for that is that there are two different ways to transfer
logs in Nix through e.g. an SSH tunnel (that are used by `ssh`/`ssh-ng`
respectively):
* `ssh://` receives its logs from the fd pointing to `builderOut`. This
is directly passed to the "log-sink" (and to the logger on each `\n`),
hence `nix log` works here.
* `ssh-ng://` however expects JSON-like messages (i.e. `@nix {log data
in here}`) and passes it directly to the logger without doing anything
with the `logSink`. However it's certainly possible to extract
log-lines from this format as these have their own message-type in the
JSON payload (i.e. `resBuildLogLine`).
This is basically what I changed in this patch: if the code-path for
`builderOut` is not reached and a `logSink` is initialized, the
message was successfully processed by the JSON logger (i.e. it's in
the expected format) and the line is of the expected type (i.e.
`resBuildLogLine`), the line will be written to the log-sink as well.
Closes#5079
There already existed a smoke test for the link content length,
but it appears that there exists some corruptions pernicious enough
to replace the file content with zeros, and keeping the same length.
--repair-path now goes as far as checking the content of the link,
making it true to its name and actually repairing the path for such
coruption cases.
Add a `_NIX_TRACE_BUILT_OUTPUTS` environment variable that can be set to
a filename in which the result of each build will be logged.
This is intentionally crude and undocumented as it’s only meant to be a
temporary thing to assess the usefulness of CA derivations.
Any other use would need a cleaner re-implementation first.
Make the build of unresolved derivations return the same status as the
resolved one, except in the case of an `AlreadyValid` in which case it
will return `ResolvesToAlreadyValid` to mean that the outputs of the unresolved
derivation weren’t known, but the resolved one is.
I downloaded Nix tonight, and immediately broke it by accidentally removing the default binary caching.
After figuring this out, I also failed to fix it properly, due to using the wrong key for Nix's default binary cache
If the diagnostic message would have been clearer about what/where a "signature" for a "substituter" is + comes from, it probably would have saved me a few hours.
Maybe we can save other noobs the same pain?
Rather than having them plain strings scattered through the whole
codebase, create an enum containing all the known experimental features.
This means that
- Nix can now `warn` when an unkwown experimental feature is passed
(making it much nicer to spot typos and spot deprecated features)
- It’s now easy to remove a feature altogether (once the feature isn’t
experimental anymore or is dropped) by just removing the field for the
enum and letting the compiler point us to all the now invalid usages
of it.
Currently machine specification (`/etc/nix/machine`) parser fails
with a vague exception if the file had incorrect format.
This commit adds verbose exceptions and unit-tests for the parser.
The garbage collector no longer blocks other processes from
adding/building store paths or adding GC roots. To prevent the
collector from deleting store paths just added by another process,
processes need to connect to the garbage collector via a Unix domain
socket to register new temporary roots.
This reverts some parts of commit
8430a8f086 which was trying to rethrow
some exceptions while we weren’t in the context of a `catch` block,
causing some weird “terminate called without an active exception”
errors.
Fix#5368
9c766a40cb broke logging from the
daemon, because commonChildInit is called when starting the build hook
in a vfork, so it ends up resetting the parent's logger. So don't
vfork.
It might be best to get rid of vfork altogether, but that may cause
problems, e.g. when we call an external program like git from the
evaluator.
Before the changes when building the whole system with
`contentAddressedByDefault = true;` we get many noninformative messages:
$ nix build -f nixos system --keep-going
...
warning: rewriting hashes in '/nix/store/...-clang-11.1.0.drv.chroot/nix/store/...-11.1.0'; cross fingers
warning: rewriting hashes in '/nix/store/...-clang-11.1.0.drv.chroot/nix/store/...-11.1.0-dev'; cross fingers
warning: rewriting hashes in '/nix/store/...-clang-11.1.0.drv.chroot/nix/store/...-11.1.0-python'; cross fingers
error: 2 dependencies of derivation '/nix/store/...-hub-2.14.2.drv' failed to build
warning: rewriting hashes in '/nix/store/...-subversion-1.14.1.drv.chroot/nix/store/...-subversion-1.14.1-dev'; cross fingers
warning: rewriting hashes in '/nix/store/...-subversion-1.14.1.drv.chroot/nix/store/...-subversion-1.14.1-man'; cross fingers
...
Let's downgrade these messages down to debug().
I had started the trend of doing `std::visit` by value (because a type
error once mislead me into thinking that was the only form that
existed). While the optomizer in principle should be able to deal with
extra coppying or extra indirection once the lambdas inlined, sticking
with by reference is the conventional default. I hope this might even
improve performance.
This actually bit me quite recently in `nixpkgs` because I assumed that
`nix-build --check` would also error out if hashes don't match anymore[1]
and so I wrongly assumed that I couldn't reproduce the mismatch error.
The fix is rather simple, during the output registration a so-called
`delayedException` is instantiated e.g. if a FOD hash-mismatch occurs.
However, in case of `nix-build --check` (or `--rebuild` in case of `nix
build`), the code-path where this exception is thrown will never be
reached.
By adding that check to the if-clause that causes an early exit in case
of `bmCheck`, the issue is gone. Also added a (previously failing)
test-case to demonstrate the problem.
[1] https://github.com/NixOS/nixpkgs/pull/139238, the underlying issue
was that `nix-prefetch-git` returns different hashes than `fetchgit`
because the latter one fetches submodules by default.
Before this commit, the dns lookup in preloadNSS would still go through
nscd. This did not have the effect of loading the nss_dns.so as expected
(nss_dns.so being out of reach from within the sandbox).
Should LOCALDOMAIN environment variable be defined, nss will completely
avoid nscd and will do its dns resolution on its own.
By temporarly setting LOCALDOMAIN variable before calling in NSS, we can
force NSS to load the shared libraries as expected.
Fixes#5089
Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
Store paths are only allowed to contain a limited subset of the
alphabet, which doesn’t include `!`. So don’t create lockfiles that
contain this `!` character as that would otherwise confuse (and break)
the gc.
Fix#5176
Maximilian Bosch
Las Safin
Sergei Trofimovich