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Disable Bpf loader V2 program deployment

Summary​

Disable BPF Loader V2 for program deployment.

Motivation​

An account on solana network is defined by the following struct. In the struct, the bool metadata field executable was used to indicate whether the account is executable by program runtime.

pub struct Account {
    pub lamports: u64,
    pub data: Vec<u8>,
    pub owner: Pubkey,
    pub executable: bool,
    pub rent_epoch: Epoch,
}

We want to deprecate the usage of executable metadata on accounts for program runtime. The new variant of Bpf loader (i.e. V3/V4 etc.) no longer requires executable metadata. However, the old Bpf loader (v2) still uses executable metadata during its program deployment. And this is a blocker for deprecating the usage of executable metadata for program runtime. Therefore, as we are migrating from the old Bpf loader V2 to the new Bpf loader (V3/V4), we are going to add a feature to disable old V2 Bpf program deployment so that we can activate the feature and deprecate executable metadata in program runtime for the new kinds of Bpf loaders.

Alternatives Considered​

None

New Terminology​

None

Detailed Design​

When the feature - "disable bpf loader instructions" is activated, no program of bpf loader V2 can be deployed. Any such deployment attempt will result in a "UnsupportedProgramId" error.

The PR for this work is at https://github.com/solana-labs/solana/pull/34194

Impact​

  1. New programs will no longer be deployable with Bpf loader V2. People will have to migrate their program deployment to a new Bpf loader, i.e. V3 or V4.

Security Considerations​

Because when the feature is activated, people should have already migrated their new programs to Bpf loader V3/V4. And existing already-deployed Bpf loader V2 programs will still run correctly. Hence, there should be no security concerns.

Backwards Compatibility​

Incompatible.