verify signature is on the from account

src/system_program.rs

@@ -36,64 +36,80 @@ pub fn id() -> Pubkey {
 pub fn get_balance(account: &Account) -> u64 {
     account.tokens
 }
-pub fn process_instruction(
-    tx: &Transaction,
-    pix: usize,
-    accounts: &mut [&mut Account],
-) -> Result<()> {
+
+fn process_instruction(tx: &Transaction, pix: usize, accounts: &mut [&mut Account]) -> Result<()> {
     if let Ok(syscall) = deserialize(tx.userdata(pix)) {
         trace!("process_instruction: {:?}", syscall);
+        let from = 0;
+
+        // all system instructions require that accounts_keys[0] be a signer
+        if tx.signed_key(pix, from).is_none() {
+            Err(Error::InvalidArgument)?;
+        }
+
         match syscall {
             SystemInstruction::CreateAccount {
                 tokens,
                 space,
                 program_id,
             } => {
-                if !check_id(&accounts[0].owner) {
-                    info!("Invalid account[0] owner");
+                let to = 1;
+
+                if !check_id(&accounts[from].owner) {
+                    info!("CreateAccount: invalid account[from] owner");
                     Err(Error::InvalidArgument)?;
                 }
 
-                if space > 0 && (!accounts[1].userdata.is_empty() || !check_id(&accounts[1].owner))
+                if space > 0
+                    && (!accounts[to].userdata.is_empty() || !check_id(&accounts[to].owner))
                 {
-                    info!("Invalid account[1]");
+                    info!(
+                        "CreateAccount: invalid argument space: {} accounts.userdata.len(): {}",
+                        space,
+                        accounts[to].userdata.len(),
+                    );
                     Err(Error::InvalidArgument)?;
                 }
-                if tokens > accounts[0].tokens {
+                if tokens > accounts[from].tokens {
                     info!(
-                        "Insufficient tokens in account[0] ({} > {})",
-                        tokens, accounts[0].tokens
+                        "CreateAccount: insufficient tokens ({}, need {})",
+                        accounts[from].tokens, tokens
                     );
                     Err(Error::ResultWithNegativeTokens)?;
                 }
-                accounts[0].tokens -= tokens;
-                accounts[1].tokens += tokens;
-                accounts[1].owner = program_id;
-                accounts[1].userdata = vec![0; space as usize];
-                accounts[1].executable = false;
-                accounts[1].loader = Pubkey::default();
+                accounts[from].tokens -= tokens;
+                accounts[to].tokens += tokens;
+                accounts[to].owner = program_id;
+                accounts[to].userdata = vec![0; space as usize];
+                accounts[to].executable = false;
+                accounts[to].loader = Pubkey::default();
             }
             SystemInstruction::Assign { program_id } => {
-                if !check_id(&accounts[0].owner) {
+                if !check_id(&accounts[from].owner) {
                     Err(Error::AssignOfUnownedAccount)?;
                 }
-                accounts[0].owner = program_id;
+                accounts[from].owner = program_id;
             }
             SystemInstruction::Move { tokens } => {
+                let to = 1;
+
                 //bank should be verifying correctness
-                if tokens > accounts[0].tokens {
-                    info!("Insufficient tokens in account[0]");
+                if tokens > accounts[from].tokens {
+                    info!(
+                        "Move: insufficient tokens ({}, need {})",
+                        accounts[from].tokens, tokens
+                    );
                     Err(Error::ResultWithNegativeTokens)?;
                 }
-                accounts[0].tokens -= tokens;
-                accounts[1].tokens += tokens;
+                accounts[from].tokens -= tokens;
+                accounts[to].tokens += tokens;
             }
             SystemInstruction::Spawn => {
-                if !accounts[0].executable || accounts[0].loader != Pubkey::default() {
+                if !accounts[from].executable || accounts[from].loader != Pubkey::default() {
                     Err(Error::AccountNotFinalized)?;
                 }
-                accounts[0].loader = accounts[0].owner;
-                accounts[0].owner = tx.account_keys[0];
+                accounts[from].loader = accounts[from].owner;
+                accounts[from].owner = tx.account_keys[from];
             }
         }
         Ok(())
@@ -124,9 +140,30 @@ mod test {
     use system_transaction::SystemTransaction;
     use transaction::Transaction;
 
+    /// Execute a function with a subset of accounts as writable references.
+    /// Since the subset can point to the same references, in any order there is no way
+    /// for the borrow checker to track them with regards to the original set.
+    fn with_subset<F, A>(accounts: &mut [Account], ixes: &[u8], func: F) -> A
+    where
+        F: FnOnce(&mut [&mut Account]) -> A,
+    {
+        let mut subset: Vec<&mut Account> = ixes
+            .iter()
+            .map(|ix| {
+                let ptr = &mut accounts[*ix as usize] as *mut Account;
+                // lifetime of this unsafe is only within the scope of the closure
+                // there is no way to reorder them without breaking borrow checker rules
+                unsafe { &mut *ptr }
+            }).collect();
+        func(&mut subset)
+    }
     fn process_transaction(tx: &Transaction, accounts: &mut [Account]) -> Result<()> {
-        let mut refs: Vec<&mut Account> = accounts.iter_mut().collect();
-        super::process_instruction(&tx, 0, &mut refs[..])
+        for (instruction_index, instruction) in tx.instructions.iter().enumerate() {
+            with_subset(accounts, &instruction.accounts, |mut program_accounts| {
+                super::process_instruction(tx, instruction_index, &mut program_accounts)
+            })?;
+        }
+        Ok(())
     }
 
     #[test]
@@ -251,7 +288,21 @@ mod test {
         assert_eq!(accounts[0].tokens, 0);
         assert_eq!(accounts[1].tokens, 1);
     }
-    /// Detect binary changes in the serialized program userdata, which could have a downstream
+
+    #[test]
+    fn test_move_many() {
+        let from = Keypair::new();
+        let tos = [(Keypair::new().pubkey(), 2), (Keypair::new().pubkey(), 1)];
+        let mut accounts = vec![Account::default(), Account::default(), Account::default()];
+        accounts[0].tokens = 3;
+        let tx = Transaction::system_move_many(&from, &tos, Hash::default(), 0);
+        process_transaction(&tx, &mut accounts).unwrap();
+        assert_eq!(accounts[0].tokens, 0);
+        assert_eq!(accounts[1].tokens, 2);
+        assert_eq!(accounts[2].tokens, 1);
+    }
+
+    // Detect binary changes in the serialized program userdata, which could have a downstream
     /// affect on SDKs and DApps
     #[test]
     fn test_sdk_serialize() {