The recent fix for CVE-2024-38531 broke the sandbox on macOS
completely. As it’s not practical to use `chroot(2)` on
macOS, the build takes place in the main filesystem tree, and the
world‐unreadable wrapper directory prevents the build from accessing
its `$TMPDIR` at all.
The macOS sandbox probably shouldn’t be treated as any kind of a
security boundary in its current state, but this specific vulnerability
wasn’t possible to exploit on macOS anyway, as creating `set{u,g}id`
binaries is blocked by sandbox policy.
Locking down the build sandbox further may be a good idea in future,
but it already has significant compatibility issues. For now, restore
the previous status quo on macOS.
Thanks to @alois31 for helping me come to a better understanding of
the vulnerability.
Fixes: 1d3696f0fbCloses: #11002
(cherry picked from commit af2e1142b1)
(cherry picked from commit 9feee13952)
After the fix for CVE-2024-38531, this was only removing the nested
build directory, rather than the top‐level temporary directory.
Fixes: 1d3696f0fb
(cherry picked from commit 76e4adfaac)
(cherry picked from commit 0d68b40dda)
When sandboxing is disabled, we cannot put $TMPDIR underneath an
inaccessible directory.
(cherry picked from commit 86ca2d6d94c0581fda0c666c5e022784952f3542)
(cherry picked from commit 8f58b98770)
Previously, the .chroot directory had permission 750 or 755 (depending
on the uid-range system feature) and was owned by root/nixbld. This
makes it possible for any nixbld user (if uid-range is disabled) or
any user (if uid-range is enabled) to inspect the contents of the
chroot of an active build and maybe interfere with it (e.g. via /tmp
in the chroot, which has 1777 permission).
To prevent this, the root is now a subdirectory of .chroot, which has
permission 700 and is owned by root/root.
(cherry picked from commit af280e72fa0e62e1c2eaccfb992c0dbb6f27f895)
With Nix 2.3, it was possible to pass a subpath of a store path to
exportReferencesGraph:
with import <nixpkgs> {};
let
hello = writeShellScriptBin "hello" ''
echo ${toString builtins.currentTime}
'';
in
writeClosure [ "${hello}/bin/hello" ]
This regressed with Nix 2.4, with a very confusing error message, that
presumably indicates it was unintentional:
error: path '/nix/store/3gl7kgjr4pwf03f0x70dgx9ln3bhl7zc-hello/bin/hello' is not in the Nix store
(cherry picked from commit 0774e8ba33)
Previously, the "file:./" prefix was not correctly recognized in
fixGitURL; instead, it was mistaken as a file path, which resulted in a
parsed url of the form "file://file:./".
This commit fixes the issue by properly detecting the "file:" prefix.
Note, however, that unlike "file://", the "file:./" URI is _not_
standardized, but has been widely used to referred to relative file
paths. In particular, the "git+file:./" did work for nix<=2.18, and was
broken since nix 2.19.0.
Finally, this commit fixes the issue completely for the 2.19 series, but
is still inadequate for the 2.20 series due to new behaviors from the
switch to libgit2. However, it does improve the correctness of parsing
even though it is not yet a complete solution.
(cherry picked from commit 8594f3cd5a)
fix old anchor redirects to point to the correct location
(cherry picked from commit 45697ba502)
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Instead of running the builds under
`$TMPDIR/{unique-build-directory-owned-by-the-build-user}`, run them
under `$TMPDIR/{unique-build-directory-owned-by-the-daemon}/{subdir-owned-by-the-build-user}`
where the build directory is only readable and traversable by the daemon user.
This achieves two things:
1. It prevents builders from making their build directory world-readable
(or even writeable), which would allow the outside world to interact
with them.
2. It prevents external processes running as the build user (either
because that somehow leaked, maybe as a consequence of 1., or because
`build-users` isn't in use) from gaining access to the build
directory.
Bind-mounting symlinks is apparently not possible, which is why the
thing was failing.
Fortunately, symlinks are small, so we can fallback to copy them at no cost.
Fix https://github.com/NixOS/nix/issues/9579
Co-authored-by: Artturin <Artturin@artturin.com>
(cherry picked from commit 913db9f738)
This requires `--substitute-on-destination` if you want the remote side
to substitute instead of copying if possible.
For completeness sake, document it here.
Also, the stable Nix from nixpkgs is still 2.18, so more folks may
stumble upon this when this is bumped, so I'd expect this to be actually
useful.
Closes#10182
(cherry picked from commit f34b8de5b2)
When querying all paths in a binary cache store, the path's representation
is `<hash>-x` (where `x` is the value of `MissingName`) because the .narinfo
filenames only contain the hash.
Before cc46ea1630 this worked correctly,
because the entire path info was read and the path from this
representation was printed, i.e. in the form `<hash>-<name>`. Since then
however, the direct result from `queryAllValidPaths()` was used as `path`.
Added a regression test to make sure the behavior remains correct.
(cherry picked from commit c80cd6bb06)
It is possible to exfiltrate a file descriptor out of the build sandbox
of FODs, and use it to modify the store path after it has been
registered.
To avoid that issue, don't register the output of the build, but a copy
of it (that will be free of any leaked file descriptor).
According to N4950 20.3.1.3.5 [unique.ptr.single.observers]/1,
the behavior is undefined if get() == nullptr. Use get() instead of
operator*() on a possibly-null unique_ptr.
Fixes#10123.
