patchlib

Documentation

Overview

Package patchlib provides common functions related to patching binaries.

Index

• func AsmBLX(pc, target uint32) []byte
• func AsmBW(pc, target uint32) []byte
• func IsCSS(r io.Reader) (bool, error)
• type Patcher
  • func NewPatcher(in []byte) *Patcher
  • func (p *Patcher) BaseAddress(offset int32) error
  • func (p *Patcher) ExtractDynsyms(needPLTGOT bool) ([]*dynsym, error)
  • func (p *Patcher) ExtractZlib() ([]ZlibItem, error)
  • func (p *Patcher) FindBaseAddress(find []byte) error
  • func (p *Patcher) FindBaseAddressString(find string) error
  • func (p *Patcher) FindBaseAddressSymbol(find string) error
  • func (p *Patcher) FindZlib(find string) error
  • func (p *Patcher) FindZlibHash(hash string) error
  • func (p *Patcher) GetBytes() []byte
  • func (p *Patcher) GetCur() int32
  • func (p *Patcher) Hook(fn func(offset int32, find, replace []byte) error)
  • func (p *Patcher) ReplaceBLX(offset int32, find, replace uint32) error
  • func (p *Patcher) ReplaceBytes(offset int32, find, replace []byte) error
  • func (p *Patcher) ReplaceBytesNOP(offset int32, find []byte) error
  • func (p *Patcher) ReplaceFloat(offset int32, find, replace float64) error
  • func (p *Patcher) ReplaceInt(offset int32, find, replace uint8) error
  • func (p *Patcher) ReplaceString(offset int32, find, replace string) error
  • func (p *Patcher) ReplaceZlib(offset int32, find, replace string) error
  • func (p *Patcher) ReplaceZlibGroup(offset int32, repl []Replacement) error
  • func (p *Patcher) ResetBaseAddress()
  • func (p *Patcher) ResolveSym(name string) (int32, error)
  • func (p *Patcher) ResolveSymPLT(name string) (int32, error)
  • func (p *Patcher) ResolveSymPLTTail(name string) (int32, error)
• type Replacement
• type ZlibItem

Functions

func AsmBLX

func AsmBLX(pc, target uint32) []byte

AsmBLX assembles a BLX instruction and returns a byte slice which can be patched directly into a binary.

func AsmBW

func AsmBW(pc, target uint32) []byte

AsmBW assembles a B.W instruction and returns a byte slice which can be patched directly into a binary.

func IsCSS

func IsCSS(r io.Reader) (bool, error)

IsCSS uses a heuristic to check if the input is likely to be CSS. There may be false negatives for invalid CSS or for CSS documents with more rules than properties, and false positives for CSS-like languages. An error is returned if and only if the io.Reader returns an error.

Types

type Patcher

type Patcher struct {
	// contains filtered or unexported fields
}

Patcher applies patches to a byte array. All operations are done starting from cur.

func NewPatcher

func NewPatcher(in []byte) *Patcher

NewPatcher creates a new Patcher.

func (*Patcher) BaseAddress

func (p *Patcher) BaseAddress(offset int32) error

BaseAddress moves cur to an offset. The offset starts at 0.

func (*Patcher) ExtractDynsyms

func (p *Patcher) ExtractDynsyms(needPLTGOT bool) ([]*dynsym, error)

func (*Patcher) ExtractZlib

func (p *Patcher) ExtractZlib() ([]ZlibItem, error)

ExtractZlib extracts all CSS zlib streams. It returns it as a map of offsets and strings.

func (*Patcher) FindBaseAddress

func (p *Patcher) FindBaseAddress(find []byte) error

FindBaseAddress moves cur to the offset of a sequence of bytes.

func (*Patcher) FindBaseAddressString

func (p *Patcher) FindBaseAddressString(find string) error

FindBaseAddressString moves cur to the offset of a string.

func (*Patcher) FindBaseAddressSymbol

func (p *Patcher) FindBaseAddressSymbol(find string) error

FindBaseAddressSymbol moves cur to the offset of a symbol by it's demangled c++ name. Warning: All symbols are off by one for historical reasons.

Deprecated: Use ResolveSym instead.

func (*Patcher) FindZlib

func (p *Patcher) FindZlib(find string) error

FindZlib finds the base address of a zlib css stream based on a substring (not sensitive to whitespace).

func (*Patcher) FindZlibHash

func (p *Patcher) FindZlibHash(hash string) error

FindZlibHash finds the base address of a zlib css stream based on it's SHA1 hash (can be found using the cssextract tool).

func (*Patcher) GetBytes

func (p *Patcher) GetBytes() []byte

GetBytes returns the current content of the Patcher.

func (*Patcher) GetCur

func (p *Patcher) GetCur() int32

GetCur gets the current base address.

func (*Patcher) Hook

func (p *Patcher) Hook(fn func(offset int32, find, replace []byte) error)

Hook sets a hook to be called right before every change. If it returns an error, it will be passed on. If nil (the default), the hook will be removed. The find and replace arguments MUST NOT be modified by the hook.

func (*Patcher) ReplaceBLX

func (p *Patcher) ReplaceBLX(offset int32, find, replace uint32) error

ReplaceBLX replaces a BLX instruction at PC (offset). Find and Replace are the target offsets.

Deprecated: Assemble the instruction with AsmBLX and use ReplaceBytes instead.

func (*Patcher) ReplaceBytes

func (p *Patcher) ReplaceBytes(offset int32, find, replace []byte) error

ReplaceBytes replaces the first occurrence of a sequence of bytes with another of the same length.

func (*Patcher) ReplaceBytesNOP

func (p *Patcher) ReplaceBytesNOP(offset int32, find []byte) error

ReplaceBytesNOP replaces an instruction with 0046 (MOV r0, r0) as many times as needed.

Deprecated: Generate the NOP externally and use ReplaceBytes instead.

func (*Patcher) ReplaceFloat

func (p *Patcher) ReplaceFloat(offset int32, find, replace float64) error

ReplaceFloat replaces the first occurrence of a float.

func (*Patcher) ReplaceInt

func (p *Patcher) ReplaceInt(offset int32, find, replace uint8) error

ReplaceInt replaces the first occurrence of an integer between 0 and 255 inclusively.

func (*Patcher) ReplaceString

func (p *Patcher) ReplaceString(offset int32, find, replace string) error

ReplaceString replaces the first occurrence of a string with another of the same length.

func (*Patcher) ReplaceZlib

func (p *Patcher) ReplaceZlib(offset int32, find, replace string) error

ReplaceZlib replaces a part of a zlib css stream at the current offset.

func (*Patcher) ReplaceZlibGroup

func (p *Patcher) ReplaceZlibGroup(offset int32, repl []Replacement) error

ReplaceZlibGroup is the same as ReplaceZlib, but it replaces all at once.

func (*Patcher) ResetBaseAddress

func (p *Patcher) ResetBaseAddress()

ResetBaseAddress moves cur to 0.

func (*Patcher) ResolveSym

func (p *Patcher) ResolveSym(name string) (int32, error)

ResolveSym resolves a mangled (fallback to unmangled) symbol name and returns its base address (error if not found). The symbol table will be loaded if not already done.

func (*Patcher) ResolveSymPLT

func (p *Patcher) ResolveSymPLT(name string) (int32, error)

ResolveSymPLT resolves a mangled (fallback to unmangled) symbol name and returns its PLT address (error if it doesn't have one). The symbol table will be loaded if not already done.

func (*Patcher) ResolveSymPLTTail

func (p *Patcher) ResolveSymPLTTail(name string) (int32, error)

ResolveSymPLTTail resolves a mangled (fallback to unmangled) symbol name and returns its PLT tail call address (error if it doesn't have one). The symbol table will be loaded if not already done.

type Replacement

type Replacement struct {
	Find, Replace string
}

Replacement is a replacement for ReplaceZlibGroup.

type ZlibItem

type ZlibItem struct {
	Offset int32
	CSS    string
}

ZlibItem is a CSS zlib stream.