Merge pull request #11044 from NixOS/backport-11031-to-2.22-maintenance

[Backport 2.22-maintenance] libstore: fix sandboxed builds on macOS
NixOS · Jul 5, 2024 · fcaa72b · fcaa72b
2 parents 5911f66 + a500c90
commit fcaa72b
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Showing 2 changed files with 23 additions and 6 deletions.
diff --git a/src/libstore/unix/build/local-derivation-goal.cc b/src/libstore/unix/build/local-derivation-goal.cc
@@ -501,13 +501,23 @@ void LocalDerivationGoal::startBuilder()
 
     /* Create a temporary directory where the build will take
        place. */
-    tmpDir = createTempDir(settings.buildDir.get().value_or(""), "nix-build-" + std::string(drvPath.name()), false, false, 0700);
+    topTmpDir = createTempDir(settings.buildDir.get().value_or(""), "nix-build-" + std::string(drvPath.name()), false, false, 0700);
+#if __APPLE__
+    if (false) {
+#else
     if (useChroot) {
+#endif
         /* If sandboxing is enabled, put the actual TMPDIR underneath
            an inaccessible root-owned directory, to prevent outside
-           access. */
-        tmpDir = tmpDir + "/build";
+           access.
+
+           On macOS, we don't use an actual chroot, so this isn't
+           possible. Any mitigation along these lines would have to be
+           done directly in the sandbox profile. */
+        tmpDir = topTmpDir + "/build";
         createDir(tmpDir, 0700);
+    } else {
+        tmpDir = topTmpDir;
     }
     chownToBuilder(tmpDir);
 
@@ -2961,15 +2971,16 @@ void LocalDerivationGoal::checkOutputs(const std::map<std::string, ValidPathInfo
 
 void LocalDerivationGoal::deleteTmpDir(bool force)
 {
-    if (tmpDir != "") {
+    if (topTmpDir != "") {
         /* Don't keep temporary directories for builtins because they
            might have privileged stuff (like a copy of netrc). */
         if (settings.keepFailed && !force && !drv->isBuiltin()) {
             printError("note: keeping build directory '%s'", tmpDir);
             chmod(tmpDir.c_str(), 0755);
         }
         else
-            deletePath(tmpDir);
+            deletePath(topTmpDir);
+        topTmpDir = "";
         tmpDir = "";
     }
 }

diff --git a/src/libstore/unix/build/local-derivation-goal.hh b/src/libstore/unix/build/local-derivation-goal.hh
@@ -27,10 +27,16 @@ struct LocalDerivationGoal : public DerivationGoal
     std::optional<Path> cgroup;
 
     /**
-     * The temporary directory.
+     * The temporary directory used for the build.
      */
     Path tmpDir;
 
+    /**
+     * The top-level temporary directory. `tmpDir` is either equal to
+     * or a child of this directory.
+     */
+    Path topTmpDir;
+
     /**
      * The path of the temporary directory in the sandbox.
      */