bpf: Refactor and streamline bounds check into helper
Move the bounds check in adjust_ptr_min_max_vals() into a small helper named sanitize_check_bounds() in order to simplify the former a bit. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org>
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@ -6075,6 +6075,37 @@ static int check_stack_access_for_ptr_arithmetic(
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return 0;
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}
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static int sanitize_check_bounds(struct bpf_verifier_env *env,
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const struct bpf_insn *insn,
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const struct bpf_reg_state *dst_reg)
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{
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u32 dst = insn->dst_reg;
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/* For unprivileged we require that resulting offset must be in bounds
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* in order to be able to sanitize access later on.
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*/
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if (env->bypass_spec_v1)
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return 0;
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switch (dst_reg->type) {
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case PTR_TO_STACK:
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if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg,
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dst_reg->off + dst_reg->var_off.value))
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return -EACCES;
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break;
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case PTR_TO_MAP_VALUE:
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if (check_map_access(env, dst, dst_reg->off, 1, false)) {
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verbose(env, "R%d pointer arithmetic of map value goes out of range, "
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"prohibited for !root\n", dst);
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return -EACCES;
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}
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break;
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default:
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break;
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}
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return 0;
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}
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/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
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* Caller should also handle BPF_MOV case separately.
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@ -6300,22 +6331,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
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__reg_deduce_bounds(dst_reg);
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__reg_bound_offset(dst_reg);
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/* For unprivileged we require that resulting offset must be in bounds
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* in order to be able to sanitize access later on.
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*/
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if (!env->bypass_spec_v1) {
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if (dst_reg->type == PTR_TO_MAP_VALUE &&
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check_map_access(env, dst, dst_reg->off, 1, false)) {
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verbose(env, "R%d pointer arithmetic of map value goes out of range, "
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"prohibited for !root\n", dst);
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return -EACCES;
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} else if (dst_reg->type == PTR_TO_STACK &&
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check_stack_access_for_ptr_arithmetic(
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env, dst, dst_reg, dst_reg->off +
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dst_reg->var_off.value)) {
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return -EACCES;
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}
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}
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if (sanitize_check_bounds(env, insn, dst_reg) < 0)
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return -EACCES;
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return 0;
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}
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