v2.0: adds feature-gate code to enforce retransmitter signature verification (backport of #1840) (#2415)

* adds feature-gate code to enforce retransmitter signature verification (#1840)

(cherry picked from commit 79cb077)

# Conflicts:
#	sdk/src/feature_set.rs

* resolves merge conflicts

---------

Co-authored-by: behzad nouri <[email protected]>

Author: mergify[bot]

sdk/src/feature_set.rs

@@ -837,6 +837,10 @@ pub mod ed25519_precompile_verify_strict {
     solana_sdk::declare_id!("ed9tNscbWLYBooxWA7FE2B5KHWs8A6sxfY8EzezEcoo");
 }
 
+pub mod verify_retransmitter_signature {
+    solana_sdk::declare_id!("BZ5g4hRbu5hLQQBdPyo2z9icGyJ8Khiyj3QS6dhWijTb");
+}
+
 lazy_static! {
     /// Map of feature identifiers to user-visible description
     pub static ref FEATURE_NAMES: HashMap<Pubkey, &'static str> = [
@@ -1041,6 +1045,7 @@ lazy_static! {
         (zk_elgamal_proof_program_enabled::id(), "Enable ZkElGamalProof program SIMD-0153"),
         (move_stake_and_move_lamports_ixs::id(), "Enable MoveStake and MoveLamports stake program instructions #1610"),
         (ed25519_precompile_verify_strict::id(), "Use strict verification in ed25519 precompile SIMD-0152"),
+        (verify_retransmitter_signature::id(), "Verify retransmitter signature #1840"),
         /*************** ADD NEW FEATURES HERE ***************/
     ]
     .iter()

turbine/src/sigverify_shreds.rs

@@ -1,6 +1,6 @@
 use {
     crate::{
-        cluster_nodes::{self, ClusterNodesCache},
+        cluster_nodes::{self, check_feature_activation, ClusterNodesCache},
         retransmit_stage::RetransmitStage,
     },
     crossbeam_channel::{Receiver, RecvTimeoutError, SendError, Sender},
@@ -19,6 +19,7 @@ use {
     },
     solana_sdk::{
         clock::Slot,
+        feature_set,
         pubkey::Pubkey,
         signature::{Keypair, Signer},
     },
@@ -201,6 +202,19 @@ fn run_shred_sigverify<const K: usize>(
                     stats
                         .num_invalid_retransmitter
                         .fetch_add(1, Ordering::Relaxed);
+                    if shred::layout::get_slot(shred)
+                        .map(|slot| {
+                            check_feature_activation(
+                                &feature_set::verify_retransmitter_signature::id(),
+                                slot,
+                                &root_bank,
+                            )
+                        })
+                        .unwrap_or_default()
+                    {
+                        packet.meta_mut().set_discard(true);
+                        return;
+                    }
                 }
                 // We can ignore Error::InvalidShredVariant because that
                 // basically means that the shred is of a variant which