https://github.com/tpm2-software/tpm2-send-tbs
Tool to bridge from WSL to TBS
https://github.com/tpm2-software/tpm2-send-tbs
Last synced: 3 months ago
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Tool to bridge from WSL to TBS
- Host: GitHub
- URL: https://github.com/tpm2-software/tpm2-send-tbs
- Owner: tpm2-software
- License: bsd-2-clause
- Created: 2023-06-16T07:01:36.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2023-11-08T08:15:18.000Z (over 1 year ago)
- Last Synced: 2024-12-23T08:43:38.104Z (4 months ago)
- Language: C
- Size: 11.7 KB
- Stars: 2
- Watchers: 4
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
Awesome Lists containing this project
README
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> [!WARNING]
> This project is in an alpha state with [known
> limitations](#limitation-some-tpm-commands-fail). Use with caution!
# tpm2-send-tbs
tpm2-send-tbs is a zero-dependency utility for sending raw bytes to the TPM.
Want to access the TPM 2.0 from within WSL2? Just compile `tpm2-send-tbs.exe`
and then call it from your WSL2 shell.
# Usage
tpm2-send-tbs takes an input stream (by default `stdin`) and an output stream
(by default `stdout`).
```cmd
tpm2-send-tbs [--debug] [--bin] [-in ] [-out ]
```
## Examples
By default, tpm2-send-tbs reads a hex stream from `stdin` and writes to
`stdout`. Here, a TPM2_GetRandom command is sent as an example:
```cmd
REM cmd.exe:
echo 80010000000c0000017b0004 | build/tpm2-send-tbs.exe
```
```bash
# bash:
printf "80010000000c0000017b0004" | build/tpm2-send-tbs.exe
```
You can use `--bin` to switch to binary format.
```bash
# bash:
printf "80010000000c0000017b0004" | xxd -r -p | build/tpm2-send-tbs.exe --bin | xxd -p
```
> [!NOTE]
> `xxd` buffers until its input pipe is closed. If a process wants to
> send multiple TPM commands, the commands/responses are a back and forth. E.g.
> tcti-cmd waits for a TPM response before sending the next command. Thus, `xxd`
> would block indefinitely, here.
>
> As an alternative, you can use the non-blocking `build/hex` and `build/unhex`.
>
> ```bash
> # bash:
> tpm2_getrandom -T "cmd: build/hex | build/tpm2-send-tbs.exe | build/unhex" --hex 4
> ```
For usage with [tpm2-tools](https://github.com/tpm2-software/tpm2-tools):
```bash
tpm2_getrandom -T "cmd: build/hex | build/tpm2-send-tbs.exe | build/unhex" --hex 4
```
> [!NOTE]
> The WSL2 pipe is broken. It turns LF into CR+LF, even if opened in
> bytewise mode. As a result, `tpm2_getrandom -T "cmd: build/tpm2-send-tbs.exe
> --bin" --hex 4` will not work.
>
> To work around this, use hex format instead of binary for input and output pipes.
# Build
In your WSL2 (or Linux), run make. This will use mingw if installed. Otherwise,
msvc will be used (requires [Build Tools for Visual Studio
2022](https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2022)).
```bash
make
```
## Compile Manually
Using mingw:
```bash
x86_64-w64-mingw32-gcc -Wall -Wextra -D_WIN32_WINNT=0x0600 src/tpm2-send-tbs.c -o tpm2-send-tbs.exe -L /mnt/c/Program\ Files\ \(x86\)/Windows\ Kits/10/Lib/*/um/x64 -l:tbs.lib
```
Alternatively, in a windows-only context:
```cmd
REM setup environment
"C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Auxiliary\Build\vcvars32.bat"
REM compile
cd build
cl /W4 src/tpm2-send-tbs.c /link tbs.lib
```
# Test
Install the [tpm2-tools](https://github.com/tpm2-software/tpm2-tools). In your
WSL2, run the smoke tests:
```
make check
```
### Limitation: Some TPM Commands Fail
At the moment, some TPM commands will fail. The root cause of this is unclear.
It could be a limitation of the TBS, insufficient priviledges or something
entirely different. Hints and patches welcome!
Example:
```bash
tpm2_nvread 0x01C00002 -T "cmd: build/hex | build/tpm2-send-tbs.exe --debug | build/unhex"
WARN: Reading full size of the NV index
read cmd[59]: 80 01 00 00 00 3b 00 00 01 76 40 00 00 07 40 00 00 07 00 20 4f 83 b6 b9 fa 2d d2 e2 30 c8 a5 ce 6d 62 ee 9b 94 45 5e 69 47 a4 52 7f 79 39 15 2c 2f e7 b5 7b 00 00 00 00 10 00 0b
send rsp[48]: 80 01 00 00 00 30 00 00 00 00 02 00 00 00 00 20 c5 db 0b a8 b1 c7 03 45 76 d2 37 1b fd dd f1 ef f9 fc 1d b8 ea 5f 57 46 90 f1 6e e6 25 16 f7 38
read cmd[14]: 80 01 00 00 00 0e 00 00 01 69 01 c0 00 02
Failed when attempting to submit TBS context: 80284001
```