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Ensure PcrSelectionList retains order #236

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102 changes: 10 additions & 92 deletions tss-esapi/src/structures/lists/pcr_selection.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ use std::convert::TryFrom;
/// corresponds to the TSS TPML_PCR_SELECTION.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PcrSelectionList {
items: HashMap<HashingAlgorithm, PcrSelection>,
items: Vec<PcrSelection>,
}

impl PcrSelectionList {
Expand All @@ -26,94 +26,23 @@ impl PcrSelectionList {
self.items.is_empty()
}

/// Gets the selections
pub fn get_selections(&self) -> &[PcrSelection] {
&self.items
}

/// Function for retrieving the PcrSelectionList from Option<PcrSelectionList>
///
/// This returns an empty list if None is passed
pub fn list_from_option(pcr_list: Option<PcrSelectionList>) -> PcrSelectionList {
pcr_list.unwrap_or_else(|| PcrSelectionListBuilder::new().build())
}

/// Removes items in `other` from `self.
///
/// # Arguments
///
/// * `other` - A PcrSelectionList containing items
/// that will be removed from `self`.
///
///
/// # Constraints
///
/// * Cannot be called with `other` that contains items that
/// are not present in `self`.
///
/// * Cannot be called with `other` that contains pcr selection
/// associated with a hashing algorithm that cannot be subtracted
/// from the pcr selection associated with the same hashing algorithm
/// in `self`.
///
/// # Errors
///
/// * Calling the method with `other` that contains items
/// not present in `self` will result in an InvalidParam error.
///
///
/// # Examples
/// ```
/// use tss_esapi::structures::{PcrSelectionListBuilder, PcrSlot};
/// use tss_esapi::interface_types::algorithm::HashingAlgorithm;
/// // pcr selections
/// let mut pcr_selection_list = PcrSelectionListBuilder::new()
/// .with_size_of_select(Default::default())
/// .with_selection(HashingAlgorithm::Sha256, &[PcrSlot::Slot0, PcrSlot::Slot8])
/// .build();
///
/// // Another pcr selections
/// let other = PcrSelectionListBuilder::new()
/// .with_size_of_select(Default::default())
/// .with_selection(
/// HashingAlgorithm::Sha256, &[PcrSlot::Slot0],
/// )
/// .build();
/// pcr_selection_list.subtract(&other).unwrap();
/// assert_eq!(pcr_selection_list.len(), 1);
/// ```
pub fn subtract(&mut self, other: &Self) -> Result<()> {
if self == other {
self.items.clear();
return Ok(());
}

if self.is_empty() {
error!("Error: Trying to remove item that did not exist");
return Err(Error::local_error(WrapperErrorKind::InvalidParam));
}

for hashing_algorithm in other.items.keys() {
// Lookup selection in self.
let pcr_selection = match self.items.get_mut(&hashing_algorithm) {
Some(val) => val,
None => {
error!("Error: Trying to remove item that did not exist");
return Err(Error::local_error(WrapperErrorKind::InvalidParam));
}
};
// Check if value exists in other and if not then nothing needs to be done
if let Some(val) = other.items.get(&hashing_algorithm) {
pcr_selection.subtract(val)?;

if pcr_selection.is_empty() {
let _ = self.items.remove(&hashing_algorithm);
}
}
}
Ok(())
}
}

impl From<PcrSelectionList> for TPML_PCR_SELECTION {
fn from(pcr_selections: PcrSelectionList) -> TPML_PCR_SELECTION {
let mut tss_pcr_selection_list: TPML_PCR_SELECTION = Default::default();
for (_, pcr_selection) in pcr_selections.items {
for pcr_selection in pcr_selections.items {
tss_pcr_selection_list.pcrSelections[tss_pcr_selection_list.count as usize] =
pcr_selection.into();
tss_pcr_selection_list.count += 1;
Expand All @@ -137,23 +66,12 @@ impl TryFrom<TPML_PCR_SELECTION> for PcrSelectionList {
return Err(Error::local_error(WrapperErrorKind::InvalidParam));
}

let mut items = HashMap::<HashingAlgorithm, PcrSelection>::new();
let mut items = Vec::<PcrSelection>::with_capacity(size);
// Loop over available selections
for tpms_pcr_selection in tpml_pcr_selection.pcrSelections[..size].iter() {
// Parse pcr selection.
let parsed_pcr_selection = PcrSelection::try_from(*tpms_pcr_selection)?;
// Insert the selection into the storage. Or merge with an existing.
match items.get_mut(&parsed_pcr_selection.hashing_algorithm()) {
Some(previously_parsed_pcr_selection) => {
previously_parsed_pcr_selection.merge(&parsed_pcr_selection)?;
}
None => {
let _ = items.insert(
parsed_pcr_selection.hashing_algorithm(),
parsed_pcr_selection,
);
}
}
items.push(parsed_pcr_selection);
}
Ok(PcrSelectionList { items })
}
Expand Down Expand Up @@ -222,7 +140,7 @@ impl PcrSelectionListBuilder {
items: self
.items
.iter()
.map(|(k, v)| (*k, PcrSelection::new(*k, size_of_select, v.as_slice())))
.map(|(k, v)| PcrSelection::new(*k, size_of_select, v.as_slice()))
.collect(),
}
}
Expand Down
4 changes: 4 additions & 0 deletions tss-esapi/src/structures/pcr/selection.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,10 @@ impl PcrSelection {
self.hashing_algorithm
}

pub fn selected_pcrs(&self) -> &BitFlags<PcrSlot> {
&self.selected_pcrs
}

pub fn merge(&mut self, other: &Self) -> Result<()> {
// Check that the hashing algorithm match
if self.hashing_algorithm != other.hashing_algorithm {
Expand Down
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