mirror of
https://github.com/vivisect/vivisect
synced 2026-06-08 18:04:23 +00:00
atlas
134 lines
3.6 KiB
Python
134 lines
3.6 KiB
Python
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"""
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A function analysis module that will find code blocks in
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functions by flow and xrefs. This is basically a mandatory
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module which should be snapped in *very* early by parsers.
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"""
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#FIXME this belongs in the core disassembler loop!
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import sys
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import envi
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import vivisect
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import collections
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from vivisect.const import *
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def analyzeFunction(vw, funcva):
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blocks = {}
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done = {}
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mnem = collections.defaultdict(int)
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todo = [ funcva, ]
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brefs = []
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size = 0
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opcount = 0
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while len(todo):
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start = todo.pop()
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# If we've hit code we've already done, keep going.
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if done.get(start):
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continue
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done[start] = True
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blocks[start] = 0
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brefs.append( (start, True) )
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va = start
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# Walk forward through instructions until a branch edge
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while True:
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loc = vw.getLocation(va)
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# If it's not a location, terminate
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if loc is None:
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blocks[start] = va - start
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brefs.append((va, False))
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break
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lva,lsize,ltype,linfo = loc
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if ltype == LOC_POINTER:
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# pointer analysis mis-identified a pointer,
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# so clear and re-analyze instructions.
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vw.delLocation(lva)
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# assume we're adding a valid instruction, which is most likely.
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vw.makeCode(va)
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loc = vw.getLocation(va)
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if loc is None:
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blocks[start] = va - start
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brefs.append( (va, False) )
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break
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lva,lsize,ltype,linfo = loc
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# If it's not an op, terminate
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if ltype != LOC_OP:
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blocks[start] = va - start
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brefs.append((va, False))
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break
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op = vw.parseOpcode(va)
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mnem[op.mnem] += 1
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size += lsize
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opcount += 1
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nextva = va+lsize
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# For each of our code xrefs, create a new target.
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branch = False
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xrefs = vw.getXrefsFrom(va, REF_CODE)
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for fromva, tova, rtype, rflags in xrefs:
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# We don't handle procedural branches here...
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if rflags & envi.BR_PROC:
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continue
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# For now, we'll skip jmp [import] thunks...
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if rflags & envi.BR_DEREF:
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continue
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branch = True
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todo.append(tova )
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# If it doesn't fall through, terminate (at nextva)
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if linfo & envi.IF_NOFALL:
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blocks[start] = nextva - start
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brefs.append( (nextva, False) )
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break
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# If we hit a branch, we are the end of a block...
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if branch:
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blocks[start] = nextva - start
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todo.append(nextva)
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break
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if vw.getXrefsTo(nextva, REF_CODE):
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blocks[start] = nextva - start
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todo.append(nextva)
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break
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va = nextva
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# we now have an ordered list of block references!
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brefs.sort()
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brefs.reverse()
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bcnt = 0
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while len(brefs):
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bva, isbegin = brefs.pop()
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if not isbegin:
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continue
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if len(brefs) == 0:
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break
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bsize = blocks[bva]
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vw.addCodeBlock(bva, bsize, funcva)
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bcnt += 1
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vw.setFunctionMeta(funcva, 'Size', size)
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vw.setFunctionMeta(funcva, 'BlockCount', bcnt)
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vw.setFunctionMeta(funcva, "InstructionCount", opcount)
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vw.setFunctionMeta(funcva, "MnemDist", mnem)
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