[zk-token-sdk] Restrict Edwards and Ristretto multiscalar multiplication vector length to at most 512 (#34763)

* restrict curve25519 multiscalar multiplication vector length to 512

* add syscall tests for msm vector length

* add new feature gate `curve25519_restrict_msm_length`

* update tests for feature new gate

* Update programs/bpf_loader/src/syscalls/mod.rs

Co-authored-by: Trent Nelson <[email protected]>

* remove length guard on the multisicalar mult lib function

---------

Co-authored-by: Trent Nelson <[email protected]>

Author: samkim-crypto

programs/bpf_loader/src/syscalls/mod.rs

@@ -1139,6 +1139,17 @@ declare_builtin_function!(
         use solana_zk_token_sdk::curve25519::{
             curve_syscall_traits::*, edwards, ristretto, scalar,
         };
+
+        let restrict_msm_length = invoke_context
+            .feature_set
+            .is_active(&feature_set::curve25519_restrict_msm_length::id());
+        #[allow(clippy::collapsible_if)]
+        if restrict_msm_length {
+            if points_len > 512 {
+                return Err(Box::new(SyscallError::InvalidLength));
+            }
+        }
+
         match curve_id {
             CURVE25519_EDWARDS => {
                 let cost = invoke_context
@@ -3146,6 +3157,122 @@ mod tests {
         assert_eq!(expected_product, result_point);
     }
 
+    #[test]
+    fn test_syscall_multiscalar_multiplication_maximum_length_exceeded() {
+        use solana_zk_token_sdk::curve25519::curve_syscall_traits::{
+            CURVE25519_EDWARDS, CURVE25519_RISTRETTO,
+        };
+
+        let config = Config::default();
+        prepare_mockup!(invoke_context, program_id, bpf_loader::id());
+
+        let scalar: [u8; 32] = [
+            254, 198, 23, 138, 67, 243, 184, 110, 236, 115, 236, 205, 205, 215, 79, 114, 45, 250,
+            78, 137, 3, 107, 136, 237, 49, 126, 117, 223, 37, 191, 88, 6,
+        ];
+        let scalars = [scalar; 513];
+        let scalars_va = 0x100000000;
+
+        let edwards_point: [u8; 32] = [
+            252, 31, 230, 46, 173, 95, 144, 148, 158, 157, 63, 10, 8, 68, 58, 176, 142, 192, 168,
+            53, 61, 105, 194, 166, 43, 56, 246, 236, 28, 146, 114, 133,
+        ];
+        let edwards_points = [edwards_point; 513];
+        let edwards_points_va = 0x200000000;
+
+        let ristretto_point: [u8; 32] = [
+            130, 35, 97, 25, 18, 199, 33, 239, 85, 143, 119, 111, 49, 51, 224, 40, 167, 185, 240,
+            179, 25, 194, 213, 41, 14, 155, 104, 18, 181, 197, 15, 112,
+        ];
+        let ristretto_points = [ristretto_point; 513];
+        let ristretto_points_va = 0x300000000;
+
+        let mut result_point: [u8; 32] = [0; 32];
+        let result_point_va = 0x400000000;
+
+        let mut memory_mapping = MemoryMapping::new(
+            vec![
+                MemoryRegion::new_readonly(bytes_of_slice(&scalars), scalars_va),
+                MemoryRegion::new_readonly(bytes_of_slice(&edwards_points), edwards_points_va),
+                MemoryRegion::new_readonly(bytes_of_slice(&ristretto_points), ristretto_points_va),
+                MemoryRegion::new_writable(bytes_of_slice_mut(&mut result_point), result_point_va),
+            ],
+            &config,
+            &SBPFVersion::V2,
+        )
+        .unwrap();
+
+        // test Edwards
+        invoke_context.mock_set_remaining(500_000);
+        let result = SyscallCurveMultiscalarMultiplication::rust(
+            &mut invoke_context,
+            CURVE25519_EDWARDS,
+            scalars_va,
+            edwards_points_va,
+            512, // below maximum vector length
+            result_point_va,
+            &mut memory_mapping,
+        );
+
+        assert_eq!(0, result.unwrap());
+        let expected_product = [
+            20, 146, 226, 37, 22, 61, 86, 249, 208, 40, 38, 11, 126, 101, 10, 82, 81, 77, 88, 209,
+            15, 76, 82, 251, 180, 133, 84, 243, 162, 0, 11, 145,
+        ];
+        assert_eq!(expected_product, result_point);
+
+        invoke_context.mock_set_remaining(500_000);
+        let result = SyscallCurveMultiscalarMultiplication::rust(
+            &mut invoke_context,
+            CURVE25519_EDWARDS,
+            scalars_va,
+            edwards_points_va,
+            513, // above maximum vector length
+            result_point_va,
+            &mut memory_mapping,
+        )
+        .unwrap_err()
+        .downcast::<SyscallError>()
+        .unwrap();
+
+        assert_eq!(*result, SyscallError::InvalidLength);
+
+        // test Ristretto
+        invoke_context.mock_set_remaining(500_000);
+        let result = SyscallCurveMultiscalarMultiplication::rust(
+            &mut invoke_context,
+            CURVE25519_RISTRETTO,
+            scalars_va,
+            ristretto_points_va,
+            512, // below maximum vector length
+            result_point_va,
+            &mut memory_mapping,
+        );
+
+        assert_eq!(0, result.unwrap());
+        let expected_product = [
+            146, 224, 127, 193, 252, 64, 196, 181, 246, 104, 27, 116, 183, 52, 200, 239, 2, 108,
+            21, 27, 97, 44, 95, 65, 26, 218, 223, 39, 197, 132, 51, 49,
+        ];
+        assert_eq!(expected_product, result_point);
+
+        invoke_context.mock_set_remaining(500_000);
+        let result = SyscallCurveMultiscalarMultiplication::rust(
+            &mut invoke_context,
+            CURVE25519_RISTRETTO,
+            scalars_va,
+            ristretto_points_va,
+            513, // above maximum vector length
+            result_point_va,
+            &mut memory_mapping,
+        )
+        .unwrap_err()
+        .downcast::<SyscallError>()
+        .unwrap();
+
+        assert_eq!(*result, SyscallError::InvalidLength);
+    }
+
     fn create_filled_type<T: Default>(zero_init: bool) -> T {
         let mut val = T::default();
         let p = &mut val as *mut _ as *mut u8;

sdk/src/feature_set.rs

@@ -146,6 +146,10 @@ pub mod curve25519_syscall_enabled {
     solana_sdk::declare_id!("7rcw5UtqgDTBBv2EcynNfYckgdAaH1MAsCjKgXMkN7Ri");
 }
 
+pub mod curve25519_restrict_msm_length {
+    solana_sdk::declare_id!("eca6zf6JJRjQsYYPkBHF3N32MTzur4n2WL4QiiacPCL");
+}
+
 pub mod versioned_tx_message_enabled {
     solana_sdk::declare_id!("3KZZ6Ks1885aGBQ45fwRcPXVBCtzUvxhUTkwKMR41Tca");
 }
@@ -950,6 +954,7 @@ lazy_static! {
         (disable_bpf_loader_instructions::id(), "disable bpf loader management instructions #34194"),
         (deprecate_executable_meta_update_in_bpf_loader::id(), "deprecate executable meta flag update in bpf loader #34194"),
         (enable_zk_proof_from_account::id(), "Enable zk token proof program to read proof from accounts instead of instruction data #34750"),
+        (curve25519_restrict_msm_length::id(), "restrict curve25519 multiscalar multiplication vector lengths #34763"),
         /*************** ADD NEW FEATURES HERE ***************/
     ]
     .iter()