auditor

An aarch64 constant-time memory access auditing tool.
git clone git://git.ppad.tech/auditor.git
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IMPL19.md (1502B)

      1 # IMPL19: STG Stack Delta Tracking
      2 
      3 ## Changes
      4 
      5 1. Add `shiftStgStackMap :: Int -> TaintState -> TaintState` in
      6    `lib/Audit/AArch64/Taint.hs`:
      7    - If delta is 0, return input.
      8    - Otherwise rebuild `tsStgStack`, `tsStgStackProv`, `tsStgStackKind`
      9      by shifting keys by `delta`.
     10    - Preserve values; drop any collisions by `IM.insert` semantics
     11      (last wins) or use `IM.fromList` (stable order is fine).
     12 
     13 2. Update transfer for `Add/Sub`:
     14    - In `Add dst r1 op` and `Sub dst r1 op`, if `dst == X20`, `r1 == X20`,
     15      and `op` is `OpImm imm`, use `shiftStgStackMap` instead of
     16      `clearStgStackMap` when updating `x20`.
     17    - Preserve existing taint/prov/kind updates for `x20`.
     18    - For any other `x20` update, keep `clearStgStackMap` behavior.
     19 
     20 3. Update pre/post-index handling in load/store helpers:
     21    - In `storeToStack` and `storePairToStack`, for `PreIndex X20 imm`
     22      and `PostIndex X20 imm`, replace `clearStgStackMap` with
     23      `shiftStgStackMap` using `imm` (post-index applies after access,
     24      so shift after storing).
     25    - In `loadFromStack` and `loadPairFromStack`, do the same for
     26      `PreIndex X20 imm` and `PostIndex X20 imm` after loading.
     27 
     28 ## Tests
     29 
     30 - Add a small fixture and unit test that seeds `stg_secret` at offset 8,
     31   then processes `sub x20, x20, #16` followed by `ldr x1, [x20, #24]` and
     32   asserts the load is tainted.
     33 - Add a symmetric test for `add x20, x20, #16` shifting the other way.
     34 
     35 ## Notes
     36 
     37 - Keep lines under 80 chars.
     38 - Avoid new dependencies.