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fix: parsing objc binds from DSC dylibs
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@blacktop
blacktop committed Apr 19, 2024
1 parent 9391308 commit e671c95
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Showing 2 changed files with 54 additions and 39 deletions.
3 changes: 2 additions & 1 deletion file.go
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,7 @@ type File struct {

var ErrMachOSectionNotFound = errors.New("MachO missing required section")
var ErrMachODyldInfoNotFound = errors.New("LC_DYLD_INFO(_ONLY) not found")
var ErrMachONoBindInfo = errors.New("MachO does not contain bind information (fixups)")

// FormatError is returned by some operations if the data does
// not have the correct format for an object file.
Expand Down Expand Up @@ -1565,7 +1566,7 @@ func (f *File) GetBindName(pointer uint64) (string, error) {
return "", fmt.Errorf("pointer %#x is not a bind", pointer)
}
}
return "", fmt.Errorf("macho does not contain fixups")
return "", ErrMachONoBindInfo
}

// GetCString returns a c-string at a given virtual address in the MachO
Expand Down
90 changes: 52 additions & 38 deletions objc.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -467,14 +467,17 @@ func (f *File) GetObjCClass(vmaddr uint64) (*objc.Class, error) {
} else {
bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.SuperclassVMAddr)))
if err != nil {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
if info.Flags.IsRoot() {
superClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
if !errors.Is(err, ErrMachONoBindInfo) {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
} else {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
if info.Flags.IsRoot() {
superClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
} else {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
}
}
}

Expand Down Expand Up @@ -509,14 +512,17 @@ func (f *File) GetObjCClass(vmaddr uint64) (*objc.Class, error) {
} else {
bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.IsaVMAddr)))
if err != nil {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
if info.Flags.IsRoot() {
isaClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
if !errors.Is(err, ErrMachONoBindInfo) {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
} else {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
if info.Flags.IsRoot() {
isaClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
} else {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
}
}
}

Expand Down Expand Up @@ -650,14 +656,17 @@ func (f *File) GetObjCClass2(vmaddr uint64) (*objc.Class, error) {
} else {
bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.SuperclassVMAddr)))
if err != nil {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
if info.Flags.IsRoot() {
superClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
if !errors.Is(err, ErrMachONoBindInfo) {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
} else {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
if info.Flags.IsRoot() {
superClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
} else {
superClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
}
}
}

Expand Down Expand Up @@ -692,14 +701,17 @@ func (f *File) GetObjCClass2(vmaddr uint64) (*objc.Class, error) {
} else {
bind, err := f.GetBindName(vmaddr + uint64(unsafe.Offsetof(classPtr.IsaVMAddr)))
if err != nil {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
if info.Flags.IsRoot() {
isaClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
if !errors.Is(err, ErrMachONoBindInfo) {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", vmaddr, err)
}
} else {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
if info.Flags.IsRoot() {
isaClass = &objc.Class{Name: bind}
} else if info.Flags.IsMeta() {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_METACLASS_$_")}
} else {
isaClass = &objc.Class{Name: strings.TrimPrefix(bind, "_OBJC_CLASS_$_")}
}
}
}

Expand Down Expand Up @@ -758,7 +770,7 @@ func (f *File) GetObjCCategories() ([]objc.Category, error) {
return nil, fmt.Errorf("failed to read %T: %v", categoryPtr, err)
}

category := objc.Category{VMAddr: f.rebasePtr(ptr)}
category := objc.Category{VMAddr: f.rebasePtr(ptr), Class: &objc.Class{}}

categoryPtr.NameVMAddr = f.vma.Convert(categoryPtr.NameVMAddr)
category.Name, err = f.GetCString(categoryPtr.NameVMAddr)
Expand All @@ -774,13 +786,13 @@ func (f *File) GetObjCCategories() ([]objc.Category, error) {
if err != nil {
if f.HasFixups() {
bindName, err := f.GetBindName(categoryPtr.ClsVMAddr)
if err == nil {
category.Class = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
if err != nil {
if !errors.Is(err, ErrMachONoBindInfo) {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", categoryPtr.ClsVMAddr, err)
}
} else {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", categoryPtr.ClsVMAddr, err)
category.Class = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
}
} else {
category.Class = &objc.Class{}
}
}
f.PutObjC(categoryPtr.ClsVMAddr, category.Class)
Expand All @@ -791,12 +803,14 @@ func (f *File) GetObjCCategories() ([]objc.Category, error) {
} else {
category.Class = &objc.Class{}
bindName, err := f.GetBindName(ptr + uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)))
if err == nil {
category.Class = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
if err != nil {
if !errors.Is(err, ErrMachONoBindInfo) {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", ptr+uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)), err)
}
} else {
return nil, fmt.Errorf("failed to read super class objc_class_t at vmaddr: %#x; %v", ptr+uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)), err)
category.Class = &objc.Class{Name: strings.TrimPrefix(bindName, "_OBJC_CLASS_$_")}
f.PutObjC(ptr+uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)), category.Class)
}
f.PutObjC(ptr+uint64(unsafe.Offsetof(categoryPtr.ClsVMAddr)), category.Class)
}
}
if categoryPtr.InstanceMethodsVMAddr > 0 {
Expand Down

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