{ "variable-offset ctx access", .insns = { /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), /* add it to skb. We now have either &skb->len or * &skb->pkt_type, but we don't know which */ BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_2), /* dereference it */ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, 0), BPF_EXIT_INSN(), }, .errstr = "variable ctx access var_off=(0x0; 0x4)", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "variable-offset stack access", .insns = { /* Fill the top 8 bytes of the stack */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8), /* add it to fp. We now have either fp-4 or fp-8, but * we don't know which */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* dereference it */ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0), BPF_EXIT_INSN(), }, .errstr = "variable stack access var_off=(0xfffffffffffffff8; 0x4)", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "indirect variable-offset stack access", .insns = { /* Fill the top 8 bytes of the stack */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8), /* add it to fp. We now have either fp-4 or fp-8, but * we don't know which */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* dereference it indirectly */ BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 5 }, .errstr = "variable stack read R2", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, },