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Merge pull request #11492 from DeterminateSystems/canon-nars

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Make the NAR parser stricter and add some tests
This commit is contained in:
Eelco Dolstra 2024-09-12 18:14:06 +02:00 committed by GitHub
parent 48477d4a3e 5737d31d4e
commit bb1ce014be
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GPG key ID: B5690EEEBB952194
9 changed files with 115 additions and 103 deletions
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184
src/libutil/archive.cc
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@ -82,7 +82,7 @@ void SourceAccessor::dumpPath(
name.erase(pos);
}
if (!unhacked.emplace(name, i.first).second)
throw Error("file name collision in between '%s' and '%s'",
throw Error("file name collision between '%s' and '%s'",
(path / unhacked[name]),
(path / i.first));
} else
@ -128,9 +128,10 @@ void dumpString(std::string_view s, Sink & sink)
}
static SerialisationError badArchive(const std::string & s)
template<typename... Args>
static SerialisationError badArchive(std::string_view s, const Args & ... args)
{
return SerialisationError("bad archive: " + s);
return SerialisationError("bad archive: " + s, args...);
}
@ -167,120 +168,97 @@ struct CaseInsensitiveCompare
static void parse(FileSystemObjectSink & sink, Source & source, const CanonPath & path)
{
std::string s;
s = readString(source);
if (s != "(") throw badArchive("expected open tag");
std::map<Path, int, CaseInsensitiveCompare> names;
auto getString = [&]() {
checkInterrupt();
return readString(source);
};
// For first iteration
s = getString();
auto expectTag = [&](std::string_view expected) {
auto tag = getString();
if (tag != expected)
throw badArchive("expected tag '%s', got '%s'", expected, tag);
};
while (1) {
expectTag("(");
if (s == ")") {
break;
}
expectTag("type");
else if (s == "type") {
std::string t = getString();
auto type = getString();
if (t == "regular") {
sink.createRegularFile(path, [&](auto & crf) {
while (1) {
s = getString();
if (type == "regular") {
sink.createRegularFile(path, [&](auto & crf) {
auto tag = getString();
if (s == "contents") {
parseContents(crf, source);
}
else if (s == "executable") {
auto s2 = getString();
if (s2 != "") throw badArchive("executable marker has non-empty value");
crf.isExecutable();
}
else break;
}
});
if (tag == "executable") {
auto s2 = getString();
if (s2 != "") throw badArchive("executable marker has non-empty value");
crf.isExecutable();
tag = getString();
}
else if (t == "directory") {
sink.createDirectory(path);
if (tag == "contents")
parseContents(crf, source);
std::string prevName;
while (1) {
s = getString();
if (s == "entry") {
std::string name;
s = getString();
if (s != "(") throw badArchive("expected open tag");
while (1) {
s = getString();
if (s == ")") {
break;
} else if (s == "name") {
name = getString();
if (name.empty() || name == "." || name == ".." || name.find('/') != std::string::npos || name.find((char) 0) != std::string::npos)
throw Error("NAR contains invalid file name '%1%'", name);
if (name <= prevName)
throw Error("NAR directory is not sorted");
prevName = name;
if (archiveSettings.useCaseHack) {
auto i = names.find(name);
if (i != names.end()) {
debug("case collision between '%1%' and '%2%'", i->first, name);
name += caseHackSuffix;
name += std::to_string(++i->second);
auto j = names.find(name);
if (j != names.end())
throw Error("NAR contains file name '%s' that collides with case-hacked file name '%s'", prevName, j->first);
} else
names[name] = 0;
}
} else if (s == "node") {
if (name.empty()) throw badArchive("entry name missing");
parse(sink, source, path / name);
} else
throw badArchive("unknown field " + s);
}
}
else break;
}
}
else if (t == "symlink") {
s = getString();
if (s != "target")
throw badArchive("expected 'target' got " + s);
std::string target = getString();
sink.createSymlink(path, target);
// for the next iteration
s = getString();
}
else throw badArchive("unknown file type " + t);
}
else
throw badArchive("unknown field " + s);
expectTag(")");
});
}
else if (type == "directory") {
sink.createDirectory(path);
std::map<Path, int, CaseInsensitiveCompare> names;
std::string prevName;
while (1) {
auto tag = getString();
if (tag == ")") break;
if (tag != "entry")
throw badArchive("expected tag 'entry' or ')', got '%s'", tag);
expectTag("(");
expectTag("name");
auto name = getString();
if (name.empty() || name == "." || name == ".." || name.find('/') != std::string::npos || name.find((char) 0) != std::string::npos)
throw badArchive("NAR contains invalid file name '%1%'", name);
if (name <= prevName)
throw badArchive("NAR directory is not sorted");
prevName = name;
if (archiveSettings.useCaseHack) {
auto i = names.find(name);
if (i != names.end()) {
debug("case collision between '%1%' and '%2%'", i->first, name);
name += caseHackSuffix;
name += std::to_string(++i->second);
auto j = names.find(name);
if (j != names.end())
throw badArchive("NAR contains file name '%s' that collides with case-hacked file name '%s'", prevName, j->first);
} else
names[name] = 0;
}
expectTag("node");
parse(sink, source, path / name);
expectTag(")");
}
}
else if (type == "symlink") {
expectTag("target");
auto target = getString();
sink.createSymlink(path, target);
expectTag(")");
}
else throw badArchive("unknown file type '%s'", type);
}

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34
tests/functional/nars.sh
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@ -67,6 +67,12 @@ expectStderr 1 nix-store --restore "$TEST_ROOT/out" < "$TEST_ROOT/tmp.nar" | gre
rm -rf "$TEST_ROOT/case"
opts=("--option" "use-case-hack" "true")
nix-store "${opts[@]}" --restore "$TEST_ROOT/case" < case.nar
[[ -e "$TEST_ROOT/case/xt_CONNMARK.h" ]]
[[ -e "$TEST_ROOT/case/xt_CONNmark.h~nix~case~hack~1" ]]
[[ -e "$TEST_ROOT/case/xt_connmark.h~nix~case~hack~2" ]]
[[ -e "$TEST_ROOT/case/x/FOO" ]]
[[ -d "$TEST_ROOT/case/x/Foo~nix~case~hack~1" ]]
[[ -e "$TEST_ROOT/case/x/foo~nix~case~hack~2/a~nix~case~hack~1/foo" ]]
nix-store "${opts[@]}" --dump "$TEST_ROOT/case" > "$TEST_ROOT/case.nar"
cmp case.nar "$TEST_ROOT/case.nar"
[ "$(nix-hash "${opts[@]}" --type sha256 "$TEST_ROOT/case")" = "$(nix-hash --flat --type sha256 case.nar)" ]
@ -92,3 +98,31 @@ else
[[ -e $TEST_ROOT/out/â ]]
[[ -e $TEST_ROOT/out/â ]]
fi
# Unpacking a NAR with a NUL character in a file name should fail.
rm -rf "$TEST_ROOT/out"
expectStderr 1 nix-store --restore "$TEST_ROOT/out" < nul.nar | grepQuiet "NAR contains invalid file name 'f"
# Likewise for a '.' filename.
rm -rf "$TEST_ROOT/out"
expectStderr 1 nix-store --restore "$TEST_ROOT/out" < dot.nar | grepQuiet "NAR contains invalid file name '.'"
# Likewise for a '..' filename.
rm -rf "$TEST_ROOT/out"
expectStderr 1 nix-store --restore "$TEST_ROOT/out" < dotdot.nar | grepQuiet "NAR contains invalid file name '..'"
# Likewise for a filename containing a slash.
rm -rf "$TEST_ROOT/out"
expectStderr 1 nix-store --restore "$TEST_ROOT/out" < slash.nar | grepQuiet "NAR contains invalid file name 'x/y'"
# Likewise for an empty filename.
rm -rf "$TEST_ROOT/out"
expectStderr 1 nix-store --restore "$TEST_ROOT/out" < empty.nar | grepQuiet "NAR contains invalid file name ''"
# Test that the 'executable' field cannot come before the 'contents' field.
rm -rf "$TEST_ROOT/out"
expectStderr 1 nix-store --restore "$TEST_ROOT/out" < executable-after-contents.nar | grepQuiet "expected tag ')', got 'executable'"
# Test that the 'name' field cannot come before the 'node' field in a directory entry.
rm -rf "$TEST_ROOT/out"
expectStderr 1 nix-store --restore "$TEST_ROOT/out" < name-after-node.nar | grepQuiet "expected tag 'name'"

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