use rbpf::ebpf; // This “verifier” performs simple checks when the eBPF program is loaded into the VM (before it is // interpreted or JIT-compiled). fn verify_prog_len(prog: &[u8]) { if prog.len() % ebpf::INSN_SIZE != 0 { panic!( "[Verifier] Error: eBPF program length must be a multiple of {:?} octets", ebpf::INSN_SIZE ); } if prog.len() > ebpf::PROG_MAX_SIZE { panic!( "[Verifier] Error: eBPF program length limited to {:?}, here {:?}", ebpf::PROG_MAX_INSNS, prog.len() / ebpf::INSN_SIZE ); } if prog.is_empty() { panic!("[Verifier] Error: program is empty"); } // TODO BPF program may deterministically exit even if the last // instruction in the block is not an exit (might be earlier and jumped to) // TODO need to validate more intelligently // let last_insn = ebpf::get_insn(prog, (prog.len() / ebpf::INSN_SIZE) - 1); // if last_insn.opc != ebpf::EXIT { // panic!("[Verifier] Error: program does not end with “EXIT” instruction"); // } } fn verify_imm_nonzero(insn: &ebpf::Insn, insn_ptr: usize) { if insn.imm == 0 { panic!("[Verifier] Error: division by 0 (insn #{:?})", insn_ptr); } } fn verify_imm_endian(insn: &ebpf::Insn, insn_ptr: usize) { match insn.imm { 16 | 32 | 64 => return, _ => panic!( "[Verifier] Error: unsupported argument for LE/BE (insn #{:?})", insn_ptr ), } } fn verify_load_dw(prog: &[u8], insn_ptr: usize) { // We know we can reach next insn since we enforce an EXIT insn at the end of program, while // this function should be called only for LD_DW insn, that cannot be last in program. let next_insn = ebpf::get_insn(prog, insn_ptr + 1); if next_insn.opc != 0 { panic!( "[Verifier] Error: incomplete LD_DW instruction (insn #{:?})", insn_ptr ); } } fn verify_jmp_offset(prog: &[u8], insn_ptr: usize) { let insn = ebpf::get_insn(prog, insn_ptr); if insn.off == -1 { panic!("[Verifier] Error: infinite loop (insn #{:?})", insn_ptr); } let dst_insn_ptr = insn_ptr as isize + 1 + insn.off as isize; if dst_insn_ptr < 0 || dst_insn_ptr as usize >= (prog.len() / ebpf::INSN_SIZE) { panic!( "[Verifier] Error: jump out of code to #{:?} (insn #{:?})", dst_insn_ptr, insn_ptr ); } let dst_insn = ebpf::get_insn(prog, dst_insn_ptr as usize); if dst_insn.opc == 0 { panic!( "[Verifier] Error: jump to middle of LD_DW at #{:?} (insn #{:?})", dst_insn_ptr, insn_ptr ); } } fn verify_registers(insn: &ebpf::Insn, store: bool, insn_ptr: usize) { if insn.src > 10 { panic!( "[Verifier] Error: invalid source register (insn #{:?})", insn_ptr ); } match (insn.dst, store) { (0...9, _) | (10, true) => {} (10, false) => panic!( "[Verifier] Error: cannot write into register r10 (insn #{:?})", insn_ptr ), (_, _) => panic!( "[Verifier] Error: invalid destination register (insn #{:?})", insn_ptr ), } } pub fn verifier(prog: &[u8]) -> bool { verify_prog_len(prog); let mut insn_ptr: usize = 0; while insn_ptr * ebpf::INSN_SIZE < prog.len() { let insn = ebpf::get_insn(prog, insn_ptr); let mut store = false; match insn.opc { // BPF_LD class ebpf::LD_ABS_B => {} ebpf::LD_ABS_H => {} ebpf::LD_ABS_W => {} ebpf::LD_ABS_DW => {} ebpf::LD_IND_B => {} ebpf::LD_IND_H => {} ebpf::LD_IND_W => {} ebpf::LD_IND_DW => {} ebpf::LD_DW_IMM => { store = true; verify_load_dw(prog, insn_ptr); insn_ptr += 1; } // BPF_LDX class ebpf::LD_B_REG => {} ebpf::LD_H_REG => {} ebpf::LD_W_REG => {} ebpf::LD_DW_REG => {} // BPF_ST class ebpf::ST_B_IMM => store = true, ebpf::ST_H_IMM => store = true, ebpf::ST_W_IMM => store = true, ebpf::ST_DW_IMM => store = true, // BPF_STX class ebpf::ST_B_REG => store = true, ebpf::ST_H_REG => store = true, ebpf::ST_W_REG => store = true, ebpf::ST_DW_REG => store = true, ebpf::ST_W_XADD => { unimplemented!(); } ebpf::ST_DW_XADD => { unimplemented!(); } // BPF_ALU class ebpf::ADD32_IMM => {} ebpf::ADD32_REG => {} ebpf::SUB32_IMM => {} ebpf::SUB32_REG => {} ebpf::MUL32_IMM => {} ebpf::MUL32_REG => {} ebpf::DIV32_IMM => { verify_imm_nonzero(&insn, insn_ptr); } ebpf::DIV32_REG => {} ebpf::OR32_IMM => {} ebpf::OR32_REG => {} ebpf::AND32_IMM => {} ebpf::AND32_REG => {} ebpf::LSH32_IMM => {} ebpf::LSH32_REG => {} ebpf::RSH32_IMM => {} ebpf::RSH32_REG => {} ebpf::NEG32 => {} ebpf::MOD32_IMM => { verify_imm_nonzero(&insn, insn_ptr); } ebpf::MOD32_REG => {} ebpf::XOR32_IMM => {} ebpf::XOR32_REG => {} ebpf::MOV32_IMM => {} ebpf::MOV32_REG => {} ebpf::ARSH32_IMM => {} ebpf::ARSH32_REG => {} ebpf::LE => { verify_imm_endian(&insn, insn_ptr); } ebpf::BE => { verify_imm_endian(&insn, insn_ptr); } // BPF_ALU64 class ebpf::ADD64_IMM => {} ebpf::ADD64_REG => {} ebpf::SUB64_IMM => {} ebpf::SUB64_REG => {} ebpf::MUL64_IMM => { verify_imm_nonzero(&insn, insn_ptr); } ebpf::MUL64_REG => {} ebpf::DIV64_IMM => { verify_imm_nonzero(&insn, insn_ptr); } ebpf::DIV64_REG => {} ebpf::OR64_IMM => {} ebpf::OR64_REG => {} ebpf::AND64_IMM => {} ebpf::AND64_REG => {} ebpf::LSH64_IMM => {} ebpf::LSH64_REG => {} ebpf::RSH64_IMM => {} ebpf::RSH64_REG => {} ebpf::NEG64 => {} ebpf::MOD64_IMM => {} ebpf::MOD64_REG => {} ebpf::XOR64_IMM => {} ebpf::XOR64_REG => {} ebpf::MOV64_IMM => {} ebpf::MOV64_REG => {} ebpf::ARSH64_IMM => {} ebpf::ARSH64_REG => {} // BPF_JMP class ebpf::JA => { verify_jmp_offset(prog, insn_ptr); } ebpf::JEQ_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JEQ_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JGT_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JGT_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JGE_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JGE_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JLT_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JLT_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JLE_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JLE_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSET_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSET_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JNE_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JNE_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSGT_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSGT_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSGE_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSGE_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSLT_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSLT_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSLE_IMM => { verify_jmp_offset(prog, insn_ptr); } ebpf::JSLE_REG => { verify_jmp_offset(prog, insn_ptr); } ebpf::CALL => {} ebpf::TAIL_CALL => unimplemented!(), ebpf::EXIT => {} _ => { panic!( "[Verifier] Error: unknown eBPF opcode {:#2x} (insn #{:?})", insn.opc, insn_ptr ); } } verify_registers(&insn, store, insn_ptr); insn_ptr += 1; } // insn_ptr should now be equal to number of instructions. if insn_ptr != prog.len() / ebpf::INSN_SIZE { panic!("[Verifier] Error: jumped out of code to #{:?}", insn_ptr); } true }