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Ryan S
e5ddbe8909
* feat(native): decode Android .note.android.ident ELF notes Decode Android NDK NT_ANDROID_TYPE_IDENT (.note.android.ident, owner Android, type 1) notes in inspect_elf_notes across legacy 4-byte and modern >=132-byte descriptors with bounded TextBudget accounting. * fix(native): isolate Android note scan budget test, scope contract import, and add feature spec * test(native): use domain tool contract in elfNotesMcp boundary test
53 lines
2.7 KiB
Markdown
53 lines
2.7 KiB
Markdown
# Android `.note.android.ident` ELF note decoding
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## Problem and outcome
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Android NDK shared libraries and executables linked with Bionic `crtbegin_so.o`
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or `crtbrand.S` embed an ELF note with `owner === "Android"` and `n_type === 1`
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(`NT_ANDROID_TYPE_IDENT`) inside `.note.android.ident` (`SHT_NOTE` and/or
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`PT_NOTE`). Legacy Android NDK (`< r14`) and unbranded platform builds store a
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4-byte `uint32_t android_api` descriptor, while modern NDK (`r14+`) builds
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store a 132-byte (or extended `>= 132`-byte) descriptor containing
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`uint32_t android_api` (`0..4`), `char ndk_version[64]` (`4..68`), and
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`char ndk_build_number[64]` (`68..132`).
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Previously, `inspect_elf_notes` / `inspect-elf-notes` mapped only `GNU` and
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`CORE` note owners, leaving `Android` type `1` entries as `type_name: "unknown"`
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with `descriptor.hex: null` for 132-byte notes (above the 64-byte inline hex
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preview ceiling). Extend `inspect_elf_notes` to decode `NT_ANDROID_TYPE_IDENT`
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into `type_name: "android_ident"` and a nullable `android` object across
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32-/64-bit and little-/big-endian ELF targets without executing the image.
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## Requirements
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- Map `owner === "Android"` and `type === 1` to `type_name: "android_ident"`;
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other `Android` note types remain `type_name: "unknown"` with `android: null`,
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and non-`Android` owners keep `android: null`.
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- Decode 4-byte `NT_ANDROID_TYPE_IDENT` descriptors in the ELF image's byte
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order as `{ android_api, ndk_version: null, ndk_build_number: null }`.
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- Decode `>= 132`-byte `NT_ANDROID_TYPE_IDENT` descriptors in the ELF image's
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byte order when both 64-byte fixed slots (`4..68` and `68..132`) contain
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printable ASCII (`0x20..0x7e`) terminated by `0x00` and padded solely with
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`0x00` through the end of each 64-byte slot.
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- Degrade truncated (`0..3` or `5..131` bytes), unterminated, control-byte, or
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non-zero-padded `NT_ANDROID_TYPE_IDENT` descriptors to `android: null` while
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preserving raw note header fields, descriptor SHA-256, and `<= 64`-byte hex
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preview.
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- Account for fixed-slot scanning (`128` bytes cached per descriptor slice in
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`TextBudget.scans`) and retained `ndk_version` / `ndk_build_number` text in
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`TextBudget.used` under the shared `max_file_bytes` ceiling.
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## Acceptance
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Domain, parser, MCP boundary, and CLI/stdio-MCP acceptance tests cover
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little-endian ELF64 (`aarch64`, `x86_64`) and big-endian ELF32/ELF64 images
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across 132-byte, 152-byte extended, and legacy 4-byte descriptors, unknown
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`Android` note types, malformed/truncated/non-ASCII descriptors, and shared
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`TextBudget` scan, scan-cache, and retained-string limits.
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## Out of scope
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Decoding other `NT_ANDROID_*` note types (such as `NT_ANDROID_TYPE_MEMTAG` or
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`NT_ANDROID_TYPE_KUSER`), executing target binaries, or invoking external
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disassemblers.
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