Fetch sysvars from invoke context for vote program (backport #22444) (#22469)

* Fetch sysvars from invoke context for vote program (#22444)

* resolve conflicts

Co-authored-by: Justin Starry <justin@solana.com>

programs/vote/src/vote_instruction.rs

@@ -16,11 +16,14 @@ use {
         feature_set,
         hash::Hash,
         instruction::{AccountMeta, Instruction, InstructionError},
-        keyed_account::{from_keyed_account, get_signers, keyed_account_at_index, KeyedAccount},
+        keyed_account::{
+            check_sysvar_keyed_account, from_keyed_account, get_signers, keyed_account_at_index,
+            KeyedAccount,
+        },
         program_utils::limited_deserialize,
         pubkey::Pubkey,
         system_instruction,
-        sysvar::{self, clock::Clock, slot_hashes::SlotHashes},
+        sysvar::{self, clock::Clock, rent::Rent, slot_hashes::SlotHashes, Sysvar},
     },
     std::collections::HashSet,
     thiserror::Error,
@@ -330,9 +333,8 @@ pub fn withdraw(
 
 fn verify_rent_exemption(
     keyed_account: &KeyedAccount,
-    rent_sysvar_account: &KeyedAccount,
+    rent: &Rent,
 ) -> Result<(), InstructionError> {
-    let rent: sysvar::rent::Rent = from_keyed_account(rent_sysvar_account)?;
     if !rent.is_exempt(keyed_account.lamports()?, keyed_account.data_len()?) {
         Err(InstructionError::InsufficientFunds)
     } else {
@@ -340,6 +342,19 @@ fn verify_rent_exemption(
     }
 }
 
+/// This method facilitates a transition from fetching sysvars from keyed
+/// accounts to fetching from the sysvar cache without breaking consensus. In
+/// order to keep consistent behavior, it continues to enforce the same checks
+/// as `solana_sdk::keyed_account::from_keyed_account` despite dynamically
+/// loading them instead of deserializing from account data.
+fn get_sysvar_with_keyed_account_check<S: Sysvar>(
+    keyed_account: &KeyedAccount,
+    invoke_context: &InvokeContext,
+) -> Result<S, InstructionError> {
+    check_sysvar_keyed_account::<S>(keyed_account)?;
+    invoke_context.get_sysvar(keyed_account.unsigned_key())
+}
+
 pub fn process_instruction(
     first_instruction_account: usize,
     data: &[u8],
@@ -358,30 +373,24 @@ pub fn process_instruction(
     let signers: HashSet<Pubkey> = get_signers(&keyed_accounts[first_instruction_account..]);
     match limited_deserialize(data)? {
         VoteInstruction::InitializeAccount(vote_init) => {
-            verify_rent_exemption(
+            let rent: Rent = get_sysvar_with_keyed_account_check(
-                me,
                 keyed_account_at_index(keyed_accounts, first_instruction_account + 1)?,
+                invoke_context,
             )?;
-            vote_state::initialize_account(
+            verify_rent_exemption(me, &rent)?;
-                me,
+            let clock: Clock = get_sysvar_with_keyed_account_check(
-                &vote_init,
+                keyed_account_at_index(keyed_accounts, first_instruction_account + 2)?,
-                &signers,
+                invoke_context,
-                &from_keyed_account::<Clock>(keyed_account_at_index(
+            )?;
-                    keyed_accounts,
+            vote_state::initialize_account(me, &vote_init, &signers, &clock)
-                    first_instruction_account + 2,
+        }
-                )?)?,
+        VoteInstruction::Authorize(voter_pubkey, vote_authorize) => {
-            )
+            let clock: Clock = get_sysvar_with_keyed_account_check(
+                keyed_account_at_index(keyed_accounts, first_instruction_account + 1)?,
+                invoke_context,
+            )?;
+            vote_state::authorize(me, &voter_pubkey, vote_authorize, &signers, &clock)
         }
-        VoteInstruction::Authorize(voter_pubkey, vote_authorize) => vote_state::authorize(
-            me,
-            &voter_pubkey,
-            vote_authorize,
-            &signers,
-            &from_keyed_account::<Clock>(keyed_account_at_index(
-                keyed_accounts,
-                first_instruction_account + 1,
-            )?)?,
-        ),
         VoteInstruction::UpdateValidatorIdentity => vote_state::update_validator_identity(
             me,
             keyed_account_at_index(keyed_accounts, first_instruction_account + 1)?.unsigned_key(),
@@ -392,19 +401,15 @@ pub fn process_instruction(
         }
         VoteInstruction::Vote(vote) | VoteInstruction::VoteSwitch(vote, _) => {
             inc_new_counter_info!("vote-native", 1);
-            vote_state::process_vote(
+            let slot_hashes: SlotHashes = get_sysvar_with_keyed_account_check(
-                me,
+                keyed_account_at_index(keyed_accounts, first_instruction_account + 1)?,
-                &from_keyed_account::<SlotHashes>(keyed_account_at_index(
+                invoke_context,
-                    keyed_accounts,
+            )?;
-                    first_instruction_account + 1,
+            let clock: Clock = get_sysvar_with_keyed_account_check(
-                )?)?,
+                keyed_account_at_index(keyed_accounts, first_instruction_account + 2)?,
-                &from_keyed_account::<Clock>(keyed_account_at_index(
+                invoke_context,
-                    keyed_accounts,
+            )?;
-                    first_instruction_account + 2,
+            vote_state::process_vote(me, &slot_hashes, &clock, &vote, &signers)
-                )?)?,
-                &vote,
-                &signers,
-            )
         }
         VoteInstruction::Withdraw(lamports) => {
             let to = keyed_account_at_index(keyed_accounts, first_instruction_account + 1)?;
@@ -512,8 +517,18 @@ mod tests {
             .collect();
 
         let mut sysvar_cache = SysvarCache::default();
-        let rent = Rent::default();
+        sysvar_cache.push_entry(
-        sysvar_cache.push_entry(sysvar::rent::id(), bincode::serialize(&rent).unwrap());
+            sysvar::rent::id(),
+            bincode::serialize(&Rent::free()).unwrap(),
+        );
+        sysvar_cache.push_entry(
+            sysvar::clock::id(),
+            bincode::serialize(&Clock::default()).unwrap(),
+        );
+        sysvar_cache.push_entry(
+            sysvar::slot_hashes::id(),
+            bincode::serialize(&SlotHashes::default()).unwrap(),
+        );
         solana_program_runtime::invoke_context::mock_process_instruction_with_sysvars(
             &id(),
             Vec::new(),
@@ -709,7 +724,7 @@ mod tests {
 
     #[test]
     fn test_minimum_balance() {
-        let rent = solana_sdk::rent::Rent::default();
+        let rent = Rent::default();
         let minimum_balance = rent.minimum_balance(VoteState::size_of());
         // golden, may need updating when vote_state grows
         assert!(minimum_balance as f64 / 10f64.powf(9.0) < 0.04)

sdk/src/keyed_account.rs

@@ -7,6 +7,7 @@ use {
     std::{
         cell::{Ref, RefCell, RefMut},
         iter::FromIterator,
+        ops::Deref,
         rc::Rc,
     },
 };
@@ -248,14 +249,20 @@ where
     }
 }
 
-pub fn from_keyed_account<S: Sysvar>(
+pub fn check_sysvar_keyed_account<'a, S: Sysvar>(
-    keyed_account: &crate::keyed_account::KeyedAccount,
+    keyed_account: &'a crate::keyed_account::KeyedAccount<'_>,
-) -> Result<S, InstructionError> {
+) -> Result<impl Deref<Target = AccountSharedData> + 'a, InstructionError> {
     if !S::check_id(keyed_account.unsigned_key()) {
         return Err(InstructionError::InvalidArgument);
     }
-    from_account::<S, AccountSharedData>(&*keyed_account.try_account_ref()?)
+    keyed_account.try_account_ref()
-        .ok_or(InstructionError::InvalidArgument)
+}
+
+pub fn from_keyed_account<S: Sysvar>(
+    keyed_account: &crate::keyed_account::KeyedAccount,
+) -> Result<S, InstructionError> {
+    let sysvar_account = check_sysvar_keyed_account::<S>(keyed_account)?;
+    from_account::<S, AccountSharedData>(&*sysvar_account).ok_or(InstructionError::InvalidArgument)
 }
 
 #[cfg(test)]