feat(multisig): make sure no members have unknown permissions

programs/multisig/src/errors.rs

@@ -60,4 +60,6 @@ pub enum MultisigError {
     SpendingLimitExceeded,
     #[msg("Decimals don't match the mint")]
     DecimalsMismatch,
+    #[msg("Member has unknown permission")]
+    UnknownPermission,
 }

programs/multisig/src/state/multisig.rs

@@ -136,6 +136,12 @@ impl Multisig {
         let has_duplicates = members.windows(2).any(|win| win[0].key == win[1].key);
         require!(!has_duplicates, MultisigError::DuplicateMember);
 
+        // Members must not have unknown permissions.
+        require!(
+            members.iter().all(|m| m.permissions.mask < 8), // 8 = Initiate | Vote | Execute
+            MultisigError::UnknownPermission
+        );
+
         // There must be at least one member with Initiate permission.
         let num_proposers = Self::num_proposers(members);
         require!(num_proposers > 0, MultisigError::NoProposers);

sdk/multisig/idl/multisig.json

@@ -2181,6 +2181,11 @@
       "code": 6028,
       "name": "DecimalsMismatch",
       "msg": "Decimals don't match the mint"
+    },
+    {
+      "code": 6029,
+      "name": "UnknownPermission",
+      "msg": "Member has unknown permission"
     }
   ],
   "metadata": {

tests/suites/multisig-sdk.ts

@@ -128,6 +128,39 @@ describe("Multisig SDK", () => {
       );
     });
 
+    it("error: member has unknown permission", async () => {
+      const creator = await generateFundedKeypair(connection);
+      const member = Keypair.generate();
+
+      const createKey = Keypair.generate();
+      const [multisigPda] = multisig.getMultisigPda({
+        createKey: createKey.publicKey,
+      });
+
+      await assert.rejects(
+        () =>
+          multisig.rpc.multisigCreate({
+            connection,
+            createKey,
+            creator,
+            multisigPda,
+            configAuthority: null,
+            timeLock: 0,
+            threshold: 1,
+            members: [
+              {
+                key: member.publicKey,
+                permissions: {
+                  mask: 1 | 2 | 4 | 8,
+                },
+              },
+            ],
+            sendOptions: { skipPreflight: true },
+          }),
+        /Member has unknown permission/
+      );
+    });
+
     // We cannot really test it because we can't pass u16::MAX members to the instruction.
     it("error: too many members");