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Commit 7506329c authored by PoroCYon's avatar PoroCYon
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hackyelf: update

parent dcac53cf
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contrib/hackyelf.py
View file @ 7506329c
......@@ -17,17 +17,43 @@ PT_LOAD = 1
PT_DYNAMIC = 2
PT_INTERP = 3
DT_NULL = 0
DT_NEEDED = 1
DT_STRTAB = 5
DT_SYMTAB = 6
DT_NULL = 0
DT_NEEDED = 1
DT_PLTGOT = 3
DT_STRTAB = 5
DT_SYMTAB = 6
DT_RELA = 7
DT_RELASZ = 8
DT_RELAENT = 9
DT_STRSZ = 10
DT_SYMENT = 11
DT_SONAME = 14
DT_REL = 17
DT_RELSZ = 18
DT_RELENT = 19
DT_PLTREL = 20
DT_DEBUG = 21
DT_TEXTREL = 22
DT_JMPREL = 23
DT_BIND_NOW= 24
SHT_NULL = 0
SHT_PROGBITS = 1
SHT_SYMTAB = 2
SHT_STRTAB = 3
SHT_RELA = 4
SHT_DYNAMIC = 6
SHT_NOBITS = 8
SHT_REL = 9
SHT_DYNSYM = 11
SHF_WRITE = 1<<0
SHF_ALLOC = 1<<1
SHF_EXECINSTR = 1<<2
SHF_MERGE = 1<<4
SHF_STRINGS = 1<<5
SHF_INFO_LINK = 1<<6
STB_LOCAL = 0
STB_GLOBAL = 1
STB_WEAK = 2
......@@ -81,6 +107,17 @@ class Sym(NamedTuple):
visibility: int
shndx: int
class Rel(NamedTuple):
offset: int
symbol: Sym
type: int
class Rela(NamedTuple):
offset: int
symbol: Sym
type: int
addend: int
Reloc = Union[Rel, Rela]
class ELF(NamedTuple):
data : bytes
ident : bytes
......@@ -92,6 +129,7 @@ class ELF(NamedTuple):
shdrs : Sequence[Shdr]
symtab: Sequence[Sym]
dynsym: Sequence[Sym]
relocs: Sequence[Reloc]
is32bit: bool
def readstr(data: bytes, off: int) -> str:
......@@ -127,6 +165,19 @@ def parse_dyn32(data: bytes, dynp: Phdr) -> Dyn:
return ds
def parse_reloc32(data: bytes, reloff: int, nrel: int, entsz: int, syms: Sequence[Sym], rela: bool) -> Reloc:
rr=[]
for off in range(reloff, reloff+entsz*nrel, entsz):
off, inf, add = unpack('<IIi', data[off:(off+12)]) if rela \
else (*unpack('<Ii', data[off:(off+8)]),0)
sym = syms[inf >> 8]
type = inf & 0xff
rr.append(Rela(off, sym, type, add) if rela else Rel(off, sym, type))
return rr
def parse_shdr32(data: bytes, shoff: int, shentsz: int, shnum: int,
shstrndx: int) -> Sequence[Shdr]:
if shnum*shentsz+shoff > len(data) or shentsz==0 or shnum==0 or shoff==0:
......@@ -165,7 +216,7 @@ def parse_sym32(data: bytes, sym: Shdr, strt: Shdr) -> Sequence[Sym]:
if noff < strt.size else None
s = Sym(sn, val, sz, (info & 15), (info >> 4), other, shndx)
ss.append(s)
return sorted(ss, key=lambda x:x.value)
return ss#sorted(ss, key=lambda x:x.value)
def parse_32(data: bytes) -> ELF:
ident = data[:16]
......@@ -181,7 +232,7 @@ def parse_32(data: bytes) -> ELF:
shnum = unpack('<H', data[48:48+2])[0]
shstrndx= unpack('<H', data[50:50+2])[0]
phdrs = parse_phdr32(data, phoff, phentsz, phnum)
phdrs = [] if phentsz == 0 else parse_phdr32(data, phoff, phentsz, phnum)
dyn = None
for p in phdrs:
......@@ -196,6 +247,8 @@ def parse_32(data: bytes) -> ELF:
strtabsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".strtab"]
dynsymsh = [s for s in shdrs if s.type == SHT_SYMTAB and s.name == ".dynsym"]
dynstrsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".dynstr"]
relash = [s for s in shdrs if s.type == SHT_RELA]
relsh = [s for s in shdrs if s.type == SHT_REL]
#print("symtab",symtabsh)
#print("strtab",strtabsh)
......@@ -213,8 +266,19 @@ def parse_32(data: bytes) -> ELF:
dynsym = parse_sym32(data, symtabsh[0], strtabsh[0]) \
if len(shdrs) > 0 else []
relocs = []
# TODO: use sh.link to use the correct symbol table
for sh in relash:
relocs += parse_reloc32(data, sh.offset, sh.size//sh.entsize,
sh.entsize, symtab, True)
for sh in relsh:
relocs += parse_reloc32(data, sh.offset, sh.size//sh.entsize,
sh.entsize, symtab, False)
# TODO: relocs from DT_RELA, DT_REL
return ELF(data, ident, eclass, mach, entry, phdrs, dyn, shdrs,
symtab, dynsym, True)
symtab, dynsym, relocs, True)
def parse_phdr64(data: bytes, phoff:int, phentsz:int, phnum:int) -> Sequence[Phdr]:
ps = []
......@@ -240,9 +304,23 @@ def parse_dyn64(data: bytes, dynp: Phdr) -> Dyn:
return ds
def parse_reloc64(data: bytes, reloff: int, nrel: int, entsz: int, syms: Sequence[Sym], rela: bool) -> Reloc:
rr=[]
for off in range(reloff, reloff+entsz*nrel, entsz):
off, inf, add = unpack('<QQq', data[off:(off+24)]) if rela \
else (*unpack('<Qq', data[off:(off+16)]),0)
sym = syms[inf >> 32]
type = inf & 0xffffffff
rr.append(Rela(off, sym, type, add) if rela else Rel(off, sym, type))
return rr
def parse_shdr64(data: bytes, shoff: int, shentsz: int, shnum: int,
shstrndx: int) -> Sequence[Shdr]:
if shnum*shentsz+shoff >= len(data) or shentsz==0 or shnum==0 or shoff==0:
if shnum*shentsz+shoff > len(data) or shentsz==0 or shnum==0 or shoff==0:
return []
ss = []
......@@ -271,9 +349,9 @@ def parse_sym64(data: bytes, sym: Shdr, strt: Shdr) -> Sequence[Sym]:
sn = readstr(data, strt.offset + noff) \
if noff < strt.size else None
s = Sym(sn, val, sz, (info & 15), (info >> 4), other, shndx)
s = Sym(sn, value, sz, (info & 15), (info >> 4), other, shndx)
ss.append(s)
return sorted(ss, key=lambda x:x.value)
return ss#sorted(ss, key=lambda x:x.value)
def parse_64(data: bytes) -> ELF:
ident = data[:16]
......@@ -289,7 +367,7 @@ def parse_64(data: bytes) -> ELF:
shnum = unpack('<H', data[60:60+2])[0]
shstrndx= unpack('<H', data[62:62+2])[0]
phdrs = parse_phdr64(data, phoff, phentsz, phnum)
phdrs = [] if phentsz == 0 else parse_phdr64(data, phoff, phentsz, phnum)
dyn = None
for p in phdrs:
......@@ -297,12 +375,14 @@ def parse_64(data: bytes) -> ELF:
dyn = parse_dyn64(data, p)
break
shdrs = parse_shdr64(data, shoff, shentsz, shnum, shstrndx)
shdrs = [] if shentsz == 0 else parse_shdr64(data, shoff, shentsz, shnum, shstrndx)
symtabsh = [s for s in shdrs if s.type == SHT_SYMTAB and s.name == ".symtab"]
strtabsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".strtab"]
dynsymsh = [s for s in shdrs if s.type == SHT_SYMTAB and s.name == ".dynsym"]
dynstrsh = [s for s in shdrs if s.type == SHT_STRTAB and s.name == ".dynstr"]
relash = [s for s in shdrs if s.type == SHT_RELA]
relsh = [s for s in shdrs if s.type == SHT_REL]
assert len(symtabsh) < 2
assert len(strtabsh) < 2
......@@ -317,8 +397,19 @@ def parse_64(data: bytes) -> ELF:
dynsym = parse_sym64(data, symtabsh[0], strtabsh[0]) \
if len(shdrs) > 0 else []
relocs = []
# TODO: use sh.link to use the correct symbol table
for sh in relash:
relocs += parse_reloc32(data, sh.offset, sh.size//sh.entsize,
sh.entsize, symtab, True)
for sh in relsh:
relocs += parse_reloc32(data, sh.offset, sh.size//sh.entsize,
sh.entsize, symtab, False)
# TODO: relocs from DT_RELA, DT_REL
return ELF(data, ident, eclass, mach, entry, phdrs, dyn, shdrs,
symtab, dynsym, False)
symtab, dynsym, relocs, False)
def parse(data: bytes) -> ELF:
assert data[:4] == b'\x7FELF', "Not a valid ELF file" # good enough
......
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