func StackInit(u models.Usercorn, args, env []string, auxv []byte) error {
// push argv and envp strings
envp, err := pushStrings(u, env...)
if err != nil {
return err
}
argv, err := pushStrings(u, args...)
if err != nil {
return err
}
// align stack pointer
sp, _ := u.RegRead(u.Arch().SP)
u.RegWrite(u.Arch().SP, (sp & ^uint64(15)))
// end marker
if _, err := u.Push(0); err != nil {
return err
}
// auxv
if len(auxv) > 0 {
if _, err := u.PushBytes(auxv); err != nil {
return err
}
}
// envp
if err := pushAddrs(u, envp); err != nil {
return err
}
// argv
if err := pushAddrs(u, argv); err != nil {
return err
}
// argc
_, err = u.Push(uint64(len(args)))
return err
}
func pushStrings(u models.Usercorn, args ...string) ([]uint64, error) {
addrs := make([]uint64, 0, len(args)+1)
for _, arg := range args {
if addr, err := u.PushBytes([]byte(arg + "\x00")); err != nil {
return nil, err
} else {
addrs = append(addrs, addr)
}
}
return addrs, nil
}
func setupElfAuxv(u models.Usercorn) ([]Elf64Auxv, error) {
// set up AT_RANDOM
var tmp [16]byte
if _, err := rand.Read(tmp[:]); err != nil {
return nil, err
}
randAddr, err := u.PushBytes(tmp[:])
if err != nil {
return nil, err
}
// insert platform string
platformAddr, err := u.PushBytes([]byte(u.Loader().Arch() + "\x00"))
if err != nil {
return nil, err
}
// main auxv table
auxv := []Elf64Auxv{
// TODO: set/track a page size somewhere - on Arch.OS?
{ELF_AT_PAGESZ, 4096},
{ELF_AT_BASE, u.InterpBase()},
{ELF_AT_FLAGS, 0},
{ELF_AT_ENTRY, uint64(u.BinEntry())},
{ELF_AT_UID, uint64(os.Getuid())},
{ELF_AT_EUID, uint64(os.Geteuid())},
{ELF_AT_GID, uint64(os.Getgid())},
{ELF_AT_EGID, uint64(os.Getegid())},
{ELF_AT_PLATFORM, platformAddr},
{ELF_AT_CLKTCK, 100}, // 100hz, totally fake
{ELF_AT_RANDOM, randAddr},
{ELF_AT_NULL, 0},
}
// add phdr information if present in binary
phdrOff, _, phdrCount := u.Loader().Header()
segments, _ := u.Loader().Segments()
for _, s := range segments {
if s.ContainsPhys(phdrOff) {
phdrOff += s.Addr
break
}
}
phdrEnt := 56
if u.Bits() == 32 {
phdrEnt = 56 // FIXME
}
if phdrOff > 0 {
auxv = append(auxv, []Elf64Auxv{
{ELF_AT_PHDR, phdrOff},
{ELF_AT_PHENT, uint64(phdrEnt)},
{ELF_AT_PHNUM, uint64(phdrCount)},
}...)
}
return auxv, nil
}
func StackInit(u models.Usercorn, args, env []string) error {
exe := u.Exe()
addr, err := u.PushBytes([]byte(exe + "\x00"))
if err != nil {
return err
}
var tmp [8]byte
auxv, err := u.PackAddr(tmp[:], addr)
if err != nil {
return err
}
err = posix.StackInit(u, args, env, auxv)
if err != nil {
return err
}
// offset to mach_header at exe[0:] in guest memory
textOffset, _, _ := u.Loader().Header()
offset := u.Base() + textOffset
_, err = u.Push(offset)
return err
}
func StackInit(u models.Usercorn, args, env []string, auxv []byte) error {
if _, err := u.Push(0); err != nil {
return err
}
if len(args) > 0 {
if _, err := u.PushBytes([]byte(args[0] + "\x00")); err != nil {
return err
}
}
// push argv and envp strings
envp, err := pushStrings(u, env...)
if err != nil {
return err
}
argv, err := pushStrings(u, args...)
if err != nil {
return err
}
// precalc envp -> argc for stack alignment
envpb, err := packAddrs(u, envp)
if err != nil {
return err
}
argvb, err := packAddrs(u, argv)
if err != nil {
return err
}
var tmp [8]byte
argcb, err := u.PackAddr(tmp[:], uint64(len(argv)))
init := append(argcb, argvb...)
init = append(init, envpb...)
// align stack pointer
sp, _ := u.RegRead(u.Arch().SP)
sp &= ^uint64(15)
off := len(init) & 15
if off > 0 {
sp -= uint64(16 - off)
}
u.RegWrite(u.Arch().SP, sp)
// auxv
if len(auxv) > 0 {
if _, err := u.PushBytes(auxv); err != nil {
return err
}
}
// write envp -> argc
u.PushBytes(init)
return err
}
