mirror of https://github.com/Shizmob/smol
233 lines
7.3 KiB
Python
233 lines
7.3 KiB
Python
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import sys
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from collections import OrderedDict
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from .shared import *
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fetch_width_from_bits = { 8: 'byte', 16: 'word', 32: 'dword', 64: 'qword' }
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def get_min_check_width(libraries, hashfn):
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minv = 8 # can't go lower
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for k, v in libraries.items():
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for sym in v:
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hv = hashfn(sym)
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#eprintf("hash: 0x%08x of %s"%(hv,sym))
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if (hv & 0xffffffff) == 0:
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# this should (hopefully) NEVER happen
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error("E: Aiee, all-zero hash for sym '%s'!" % sym)
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elif (hv & 0xFFFF) == 0:
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#eprintf("32-bit hash")
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minv = max(minv, 32) # need at least 32 bits
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elif (hv & 0xFF) == 0:
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#eprintf("16-bit hash")
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minv = max(minv, 16) # need at least 16 bits
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return minv
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def sort_imports(libraries, hashfn):
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#eprintf("in: " + str(libraries))
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# DON'T DO THIS: weak symbol stuff etc.
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## sort libs by name length, then by name
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#ll = sorted(libraries.items(), key=lambda ls: (len(ls[0]), ls[0]))
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#for i in range(len(ll)):
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# # sort symbols by hash value
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# ll[i] = (ll[i][0], sorted(ll[i][1], key=lambda sr: hashfn(sr[0])))
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#eprintf("out:" + str(dict(ll)))
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# insertion order only works with python >=3.6!
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#if sys.version_info < (3, 6): return OrderedDict(ll)
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#else: return dict(ll)
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for k, v in libraries.items():
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libraries[k] = OrderedDict(sorted(v.items(), key=lambda sr: hashfn(sr[0])))
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return libraries
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def output_x86(libraries, nx, hashid, outf, det):
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outf.write('; vim: set ft=nasm:\n') # be friendly
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defff = define_for_hash[hashid]
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if defff is not None:
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outf.write('%define {} 1\n'.format(defff))
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if nx:
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outf.write('%define USE_NX 1\n')
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hashfn = get_hash_fn(hashid)
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if det: libraries = sort_imports(libraries, hashfn)
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outf.write('%%define HASH_END_TYP %s\n' %
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fetch_width_from_bits[get_min_check_width(libraries, hashfn)])
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usedrelocs = set()
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for library, symrels in libraries.items():
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for sym, reloc in symrels.items():
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usedrelocs.add(reloc)
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if not(nx) and 'R_386_PC32' in usedrelocs and 'R_386_GOT32X' in usedrelocs:
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error("Using a mix of R_386_PC32 and R_386_GOT32X relocations! "+\
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"Please change a few C compiler flags and recompile your code.")
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use_jmp_bytes = not nx and 'R_386_PC32' in usedrelocs
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if use_jmp_bytes:
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outf.write('%define USE_JMP_BYTES 1\n')
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outf.write('bits 32\n')
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shorts = { l: l.split('.', 1)[0].lower().replace('-', '_') for l in libraries }
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outf.write('%include "header32.asm"\n')
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outf.write('dynamic.needed:\n')
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for library in libraries:
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outf.write('dd 1;DT_NEEDED\n')
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outf.write('dd (_symbols.{} - _strtab)\n'.format(shorts[library]))
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outf.write("""\
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dynamic.end:
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%ifndef UNSAFE_DYNAMIC
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dd DT_NULL
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%endif
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""")
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outf.write('[section .rodata.neededlibs]\n')
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outf.write('global _strtab\n')
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outf.write('_strtab:\n')
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for library, symrels in libraries.items():
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outf.write('\t_symbols.{}: db "{}",0\n'.format(shorts[library], library))
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outf.write('[section .data.smolgot]\n')
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if not nx:
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outf.write('[section .text.smolplt]\n')
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outf.write('global _symbols\n')
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outf.write('_symbols:\n')
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for library, symrels in libraries.items():
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for sym, reloc in symrels.items():
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# meh
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if reloc != 'R_386_PC32' and reloc != 'R_386_GOT32X':
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eprintf('Relocation type %s of symbol %s unsupported!' % (reloc, sym))
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sys.exit(1)
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if nx:
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outf.write("\t\t_symbols.{lib}.{name}: dd 0x{hash:x}"\
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.format(lib=shorts[library],name=sym,hash=hashfn(sym)).lstrip('\n'))
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else:
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outf.write(("""\
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\t\tglobal {name}
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\t\t{name}:""" + ("\n\t\t\tdb 0xE9" if use_jmp_bytes else '') + """
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\t\t\tdd 0x{hash:x}
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""").format(name=sym, hash=hashfn(sym)).lstrip('\n'))
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outf.write('db 0\n')
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outf.write('_symbols.end:\n')
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if nx:
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outf.write('global _smolplt\n')
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outf.write('_smolplt:\n')
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for library, symrels in libraries.items():
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for sym, reloc in symrels.items():
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outf.write("""\
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[section .text.smolplt.{name}]
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global {name}
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{name}:
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\tjmp [dword _symbols.{lib}.{name}]
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""".format(lib=shorts[library],name=sym).lstrip('\n'))
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outf.write('_smolplt.end:\n')
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outf.write('%include "loader32.asm"\n')
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# end output_x86
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def output_amd64(libraries, nx, hashid, outf, det):
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if hashid == HASH_BSD2:
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error("--hash16 not supported yet for x86_64 outputs.")
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outf.write('; vim: set ft=nasm:\n')
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outf.write('bits 64\n')
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defff = define_for_hash[hashid]
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if defff is not None:
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outf.write('%define {} 1\n'.format(defff))
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if nx:
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outf.write('%define USE_NX 1\n')
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hashfn = get_hash_fn(hashid)
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if det: libraries = sort_imports(libraries, hashfn)
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outf.write('%%define HASH_END_TYP %s\n' %
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fetch_width_from_bits[get_min_check_width(libraries, hashfn)])
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shorts = { l: l.split('.', 1)[0].lower().replace('-', '_') for l in libraries }
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outf.write('%include "header64.asm"\n')
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outf.write('dynamic.needed:\n')
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for library in libraries:
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outf.write(' dq 1;DT_NEEDED\n')
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outf.write(' dq (_symbols.{} - _strtab)\n'.format(shorts[library]))
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outf.write("""\
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dynamic.symtab:
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dq DT_SYMTAB ; d_tag
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dq 0 ; d_un.d_ptr
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dynamic.end:
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%ifndef UNSAFE_DYNAMIC
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dq DT_NULL
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%endif
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""")
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outf.write('[section .rodata.neededlibs]\n')
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outf.write('global _strtab\n')
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outf.write('_strtab:\n')
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for library, symrels in libraries.items():
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outf.write('\t_symbols.{}: db "{}",0\n'.format(shorts[library], library))
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outf.write('[section .data.smolgot]\n')
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outf.write('global _symbols\n')
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outf.write('_symbols:\n')
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for library, symrels in libraries.items():
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for sym, reloc in symrels.items():
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if reloc not in ['R_X86_64_PLT32', 'R_X86_64_GOTPCRELX', \
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'R_X86_64_REX_GOTPCRELX', 'R_X86_64_GOTPCREL']:
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error('Relocation type %s of symbol %s unsupported!' % (reloc, sym))
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if reloc in ['R_X86_64_GOTPCRELX', 'R_X86_64_REX_GOTPCRELX', \
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'R_X86_64_GOTPCREL']:
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outf.write("""
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global {name}
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{name}:
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""".format(name=sym).lstrip('\n'))
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outf.write('\t\t_symbols.{lib}.{name}: dq 0x{hash:x}\n'\
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.format(lib=shorts[library],name=sym,hash=hashfn(sym)))
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outf.write('db 0\n')
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outf.write('_symbols.end:\n')
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outf.write('global _smolplt\n')
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outf.write('_smolplt:\n')
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for library, symrels in libraries.items():
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for sym, reloc in symrels.items():
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if reloc == 'R_X86_64_PLT32':
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outf.write("""\
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[section .text.smolplt.{name}]
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global {name}
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{name}:
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\tjmp [rel _symbols.{lib}.{name}]
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""".format(lib=shorts[library],name=sym).lstrip('\n'))
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outf.write('_smolplt.end:\n')
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outf.write('%include "loader64.asm"\n')
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# end output_amd64
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def output(arch, libraries, nx, hashid, outf, det):
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if arch == 'i386': output_x86(libraries, nx, hashid, outf, det)
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elif arch == 'x86_64': output_amd64(libraries, nx, hashid, outf, det)
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else:
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error("E: cannot emit for arch '%s'" % str(arch))
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