Implements TPM vendor check function #113
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This change implements a means to check the vendor of the TPM. The main use for this function is to establish if we are using a software based TPM and in turn warn that no hardware root of trust is available
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Still learning the idioms of rust, if you feel anything can be improved / optimised let me know of follow up with a commit
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src/tpm.rs
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| use tss_esapi::tss2_esys::{ESYS_TR, ESYS_TR_NONE, ESYS_TR_RH_OWNER}; | ||
| use tss_esapi::Context; | ||
| use tss_esapi::Tcti; | ||
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| fn int_to_str(num: u32) -> String { |
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Function name
This is really moving to a String rather than str
| fn int_to_str(num: u32) -> String { | |
| fn int_to_string(num: u32) -> String { |
Possibly simpler implementation
fn int_to_string(num: u32) -> String {
num.to_string()
}
Or directly using to_string() 😄
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Well, it's not really a standard integer-to-string operation. It's basically parsing every byte in a u32 (i.e. up to 4 bytes) as a different ascii character. Because that's how TPM does strings.
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(Renaming to int_to_string is reasonable though)
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| } | ||
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| let mut vend_strs: String = [ |
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nit: My brain turns to mush when I see many map/filter/etc.. statements on something. Consider adding a comment explaining what's going on here for folks like me 😆.
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Yeah, sorry. Let me explain what's going on, so Luke can add comments.
This basically first uses a set of constants (TPM2_PT_VENDOR_STRING_{1,2,3,4}) as lookup indexes into allprops, to get all the values from there where they're set. After that, it removes the values that don't exist (is_some), removes the Option<_> wrappers (unwrap()), removes the items that are actually a value (i.e. != && 0), then puts the individual parts to a different through int_to_str to get a Vec<String> with the parts, and then makes a single string from them (.join("")).
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I added comments. in time we can move this into a helper function (if they all need the some manipulation)
src/tpm.rs
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| * software TPM as opposed to hardware TPM. | ||
| */ | ||
| pub fn get_tpm_vendor() -> Result<String, tss_esapi::Error> { | ||
| let mut ctx = get_tpm2_ctx()?; |
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I think you want to get the context in main() and pass that one through to here as &mut Context.
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After speaking with @puiterwijk , I will close this and he will follow up with a patch implementing the same, but using his new error code contained within PR #121 |
This change implements a means to check the vendor of the TPM.
The main use for this function is to establish if we are using
a software based TPM and in turn warn that no hardware root of
trust is available