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fix: harden workspace preprocessing contract

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This commit is contained in:
marcopan
2026-08-11 00:59:15 +02:00
parent 9df7c38069
commit 05a6e8cc2d
11 changed files with 494 additions and 32 deletions
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tools/thothctl/internal/safeio/files_unix.go
+4 -4
View File
@@ -90,7 +90,7 @@ func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) err
if err != nil {
return ErrUnsafeFile
}
defer unix.Close(dir)
defer func() { unix.Close(dir) }()
for _, component := range components[:len(components)-1] {
next, err := unix.Openat(dir, component, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_CLOEXEC|unix.O_NOFOLLOW, 0)
if err != nil {
@@ -147,7 +147,7 @@ func validateCanonicalOutputPath(path string) error {
if err != nil {
return ErrUnsafeFile
}
defer unix.Close(dir)
defer func() { unix.Close(dir) }()
for _, component := range components[:len(components)-1] {
next, err := unix.Openat(dir, component, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_CLOEXEC|unix.O_NOFOLLOW, 0)
if err != nil {
@@ -173,7 +173,7 @@ func recheckUnixParents(components []string, retained []int) bool {
if err != nil {
return false
}
defer unix.Close(dir)
defer func() { unix.Close(dir) }()
for i, component := range components[:len(components)-1] {
next, e := unix.Openat(dir, component, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_CLOEXEC|unix.O_NOFOLLOW, 0)
if e != nil {
@@ -195,7 +195,7 @@ func recheckUnixParentPath(components []string, retained int) bool {
if err != nil {
return false
}
defer unix.Close(dir)
defer func() { unix.Close(dir) }()
for _, component := range components {
next, e := unix.Openat(dir, component, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_CLOEXEC|unix.O_NOFOLLOW, 0)
if e != nil {
tools/thothctl/internal/safeio/files_unix_test.go
+48
View File
@@ -30,3 +30,51 @@ func TestReadCanonicalRegularRejectsNamedPipeWithoutBlocking(t *testing.T) {
t.Fatalf("named pipe error = %v, want ErrUnsafeFile", err)
}
}
func TestCanonicalDescriptorOwnershipDoesNotLeakAcrossNestedOperations(t *testing.T) {
root, err := filepath.EvalSymlinks(t.TempDir())
if err != nil {
t.Fatal(err)
}
nested := filepath.Join(root, "one", "two")
if err := os.MkdirAll(nested, 0o700); err != nil {
t.Fatal(err)
}
input := filepath.Join(nested, "input.sql")
if err := os.WriteFile(input, []byte("select 1"), 0o600); err != nil {
t.Fatal(err)
}
fdCount := func() int {
f, err := os.Open("/dev/fd")
if err != nil {
t.Fatal(err)
}
defer f.Close()
names, err := f.Readdirnames(-1)
if err != nil {
t.Fatal(err)
}
return len(names)
}
baseline := fdCount()
for i := 0; i < 20; i++ {
if _, err := ReadCanonicalRegular(input, 1024); err != nil {
t.Fatal(err)
}
if err := validateCanonicalOutputPath(filepath.Join(nested, "out-"+string(rune('a'+i))+".yaml")); err != nil {
t.Fatal(err)
}
}
if got := fdCount(); got > baseline+2 {
t.Fatalf("descriptor leak after read/validate: baseline=%d got=%d", baseline, got)
}
for i := 0; i < 20; i++ {
path := filepath.Join(nested, "write-"+string(rune('a'+i))+".yaml")
if err := writeCanonicalExclusive(path, []byte("ok"), 0o600); err != nil {
t.Fatal(err)
}
}
if got := fdCount(); got > baseline+2 {
t.Fatalf("descriptor leak after writes: baseline=%d got=%d", baseline, got)
}
}
tools/thothctl/internal/safeio/files_windows.go
+30 -9
View File
@@ -122,7 +122,14 @@ func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) err
if err := ValidateCanonicalPath(path); err != nil || len(contents) > 16<<20 || mode.Perm() == 0 || mode.Perm()&0o077 != 0 {
return ErrUnsafeFile
}
h, err := windows.CreateFile(windows.StringToUTF16Ptr(path), windows.GENERIC_WRITE, 0, nil, windows.CREATE_NEW, windows.FILE_ATTRIBUTE_NORMAL|windows.FILE_FLAG_OPEN_REPARSE_POINT, 0)
parent, retainedParents, err := openWindowsParents(path)
if err != nil {
return ErrUnsafeFile
}
defer closeWindowsHandles(retainedParents)
// Parent handles stay open with delete sharing denied until publication and
// identity recheck complete; this is the Windows equivalent of retained dirfds.
h, err := windows.CreateFile(windows.StringToUTF16Ptr(filepath.Join(parent, filepath.Base(path))), windows.GENERIC_WRITE, 0, nil, windows.CREATE_NEW, windows.FILE_ATTRIBUTE_NORMAL|windows.FILE_FLAG_OPEN_REPARSE_POINT, 0)
if err != nil {
return ErrUnsafeFile
}
@@ -132,6 +139,9 @@ func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) err
return ErrUnsafeFile
}
defer f.Close()
if err := f.Chmod(mode); err != nil {
return ErrUnsafeFile
}
if _, err := f.Write(contents); err != nil {
return ErrUnsafeFile
}
@@ -153,26 +163,37 @@ func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) err
return nil
}
func validateCanonicalOutputPath(path string) error {
if err := ValidateCanonicalPath(path); err != nil {
return err
}
func openWindowsParents(path string) (string, []windows.Handle, error) {
volume := filepath.VolumeName(path)
root := volume + string(filepath.Separator)
components := strings.Split(strings.TrimPrefix(path, root), string(filepath.Separator))
if volume == "" || len(components) < 2 || components[0] == "" {
return ErrUnsafeFile
return "", nil, ErrUnsafeFile
}
current := root
parents := make([]windows.Handle, 0, len(components)-1)
for _, component := range components[:len(components)-1] {
current = filepath.Join(current, component)
h, err := openWindowsComponent(current, true)
if err != nil {
return ErrUnsafeFile
closeWindowsHandles(parents)
return "", nil, ErrUnsafeFile
}
windows.CloseHandle(h)
parents = append(parents, h)
}
if _, err := os.Lstat(filepath.Join(current, components[len(components)-1])); err == nil || !os.IsNotExist(err) {
return current, parents, nil
}
func validateCanonicalOutputPath(path string) error {
if err := ValidateCanonicalPath(path); err != nil {
return err
}
current, parents, err := openWindowsParents(path)
if err != nil {
return ErrUnsafeFile
}
defer closeWindowsHandles(parents)
if _, err := os.Lstat(filepath.Join(current, filepath.Base(path))); err == nil || !os.IsNotExist(err) {
return ErrUnsafeFile
}
return nil
tools/thothctl/internal/safeio/files_windows_test.go
+6
View File
@@ -66,3 +66,9 @@ func TestOpenWindowsComponentBlocksMutationWhileHandleIsRetained(t *testing.T) {
}
})
}
func TestWriteCanonicalExclusiveRequiresRestrictiveMode(t *testing.T) {
if err := writeCanonicalExclusive(`C:\\tmp\\thothctl-output.yaml`, []byte("x"), 0o640); err == nil {
t.Fatal("accepted non-restrictive output mode")
}
}