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Generalize traversing a Clevis config #3708

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Generalize traversing a Clevis config #3708

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1eb8dee
Generalize traversing a Clevis config
mulkieran Oct 14, 2024
818b9e9
Make the first element of sss a value not a reference
mulkieran Nov 19, 2024
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98 changes: 76 additions & 22 deletions src/engine/strat_engine/crypt/shared.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -204,14 +204,40 @@ pub fn clevis_info_from_metadata(
pin_dispatch(&subjson, CLEVIS_RECURSION_LIMIT).map(Some)
}

/// Returns true if the Tang config has a thumbprint or an advertisement
/// or all Tang configs in the nested sss config have thumbprints or
/// advertisements.
fn all_tang_configs_have_url_trust_info(
/// Generic traversal of a Clevis config.
/// Apply the specified simple functions to tang and tpm2 configs.
/// The sss parameter is the initial value and function for a try_fold
/// action for an sss pin. The sss function is a FnMut in order to be
/// able to update the accumulator.
///
/// fn example(
/// pin: &str,
/// clevis_config: &Value,
/// recursion_limit: u64,
/// ) -> StratisResult<Vec<u32>> {
/// traverse_clevis_config(
/// pin,
/// clevis_config,
/// recursion_limit,
/// &|_obj| Ok(Vec::new()),
/// &|_| Ok(Vec::new()),
/// &mut (Vec::new(), &mut |mut acc, _premise| {
/// acc.push(2);
/// Ok(acc)
/// }),
/// )
/// }
fn traverse_clevis_config<T>(
pin: &str,
clevis_config: &Value,
recursion_limit: u64,
) -> StratisResult<bool> {
tang_func: &dyn Fn(&Map<String, Value>) -> StratisResult<T>,
tpm2_func: &dyn Fn(&Map<String, Value>) -> StratisResult<T>,
sss: &mut (T, &mut dyn FnMut(T, T) -> StratisResult<T>),
) -> StratisResult<T>
where
T: Clone,
{
if recursion_limit == 0 {
return Err(StratisError::Msg(
"Reached the recursion limit for parsing nested SSS tokens".to_string(),
Expand All @@ -220,14 +246,7 @@ fn all_tang_configs_have_url_trust_info(

if pin == "tang" {
if let Some(obj) = clevis_config.as_object() {
Ok(obj
.get("thp")
.map(|val| val.as_str().is_some())
.or_else(|| {
obj.get("adv")
.map(|val| val.as_str().is_some() || val.as_object().is_some())
})
.unwrap_or(false))
tang_func(obj)
} else {
Err(StratisError::Msg(format!(
"configuration for Clevis is is not in JSON object format: {clevis_config}"
Expand All @@ -236,14 +255,16 @@ fn all_tang_configs_have_url_trust_info(
} else if pin == "sss" {
if let Some(obj) = clevis_config.as_object() {
if let Some(obj) = obj.get("pins").and_then(|val| val.as_object()) {
obj.iter().try_fold(true, |b, (pin, config)| {
Ok(
b && all_tang_configs_have_url_trust_info(
pin,
config,
recursion_limit - 1,
)?,
)
obj.iter().try_fold(sss.0.clone(), |acc, (pin, config)| {
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Can you explain why you opted for a reference here? My brief analysis of the ownership here leads me to believe that a move and an owned data type would be okay here.

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I can change sss.0 so that it is not a reference. I've added a commit for that. But you can't move sss into the closure, because it is used after the closure returns. So, AFAICT, if you add a move, you have to be able to clone sss.

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I think this gets back to my other comment: why do all of these need to be references? I feel like ownership may remove the need for cloning.

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sss is recursively passed and then used on the return value. I don't believe that it can be moved into the closure for that reason.

let res = traverse_clevis_config(
pin,
config,
recursion_limit - 1,
tang_func,
tpm2_func,
sss,
)?;
sss.1(acc, res)
})
} else {
Err(StratisError::Msg(
Expand All @@ -256,12 +277,45 @@ fn all_tang_configs_have_url_trust_info(
)))
}
} else if pin == "tpm2" {
Ok(true)
if let Some(obj) = clevis_config.as_object() {
tpm2_func(obj)
} else {
Err(StratisError::Msg(format!(
"configuration for Clevis is is not in JSON object format: {clevis_config}"
)))
}
} else {
Err(StratisError::Msg(format!("Unrecognized pin {pin}")))
}
}

/// Returns true if the Tang config has a thumbprint or an advertisement
/// or all Tang configs in the nested sss config have thumbprints or
/// advertisements.
fn all_tang_configs_have_url_trust_info(
pin: &str,
clevis_config: &Value,
recursion_limit: u64,
) -> StratisResult<bool> {
traverse_clevis_config(
pin,
clevis_config,
recursion_limit,
&|obj| {
Ok(obj
.get("thp")
.map(|val| val.as_str().is_some())
.or_else(|| {
obj.get("adv")
.map(|val| val.as_str().is_some() || val.as_object().is_some())
})
.unwrap_or(false))
},
&|_| Ok(true),
&mut (true, &mut |acc, premise| Ok(acc && premise)),
)
}

/// Interpret non-Clevis keys that may contain additional information about
/// how to configure Clevis when binding. Remove any expected non-Clevis keys
/// from the configuration.
Expand Down