bpf: Move sanitize_val_alu out of op switch

Add a small sanitize_needed() helper function and move sanitize_val_alu()
out of the main opcode switch. In upcoming work, we'll move sanitize_ptr_alu()
as well out of its opcode switch so this helps to streamline both.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index db77e2c..e41b632 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5945,6 +5945,11 @@ static int sanitize_val_alu(struct bpf_verifier_env *env,
        return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
 }
 
+static bool sanitize_needed(u8 opcode)
+{
+       return opcode == BPF_ADD || opcode == BPF_SUB;
+}
+
 static int sanitize_ptr_alu(struct bpf_verifier_env *env,
                            struct bpf_insn *insn,
                            const struct bpf_reg_state *ptr_reg,
@@ -6968,6 +6973,12 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
                return 0;
        }
 
+       if (sanitize_needed(opcode)) {
+               ret = sanitize_val_alu(env, insn);
+               if (ret < 0)
+                       return sanitize_err(env, insn, ret, NULL, NULL);
+       }
+
        /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
         * There are two classes of instructions: The first class we track both
         * alu32 and alu64 sign/unsigned bounds independently this provides the
@@ -6984,17 +6995,11 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
         */
        switch (opcode) {
        case BPF_ADD:
-               ret = sanitize_val_alu(env, insn);
-               if (ret < 0)
-                       return sanitize_err(env, insn, ret, NULL, NULL);
                scalar32_min_max_add(dst_reg, &src_reg);
                scalar_min_max_add(dst_reg, &src_reg);
                dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
                break;
        case BPF_SUB:
-               ret = sanitize_val_alu(env, insn);
-               if (ret < 0)
-                       return sanitize_err(env, insn, ret, NULL, NULL);
                scalar32_min_max_sub(dst_reg, &src_reg);
                scalar_min_max_sub(dst_reg, &src_reg);
                dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);