diff options
| -rw-r--r-- | kernel/bpf/btf.c | 94 |
1 files changed, 73 insertions, 21 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index b3fddfb5bc84..33bb8ae4a804 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5576,12 +5576,53 @@ static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = { #endif }; +/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */ +static bool __btf_type_is_scalar_struct(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int rec) +{ + const struct btf_type *member_type; + const struct btf_member *member; + u32 i; + + if (!btf_type_is_struct(t)) + return false; + + for_each_member(i, t, member) { + const struct btf_array *array; + + member_type = btf_type_skip_modifiers(btf, member->type, NULL); + if (btf_type_is_struct(member_type)) { + if (rec >= 3) { + bpf_log(log, "max struct nesting depth exceeded\n"); + return false; + } + if (!__btf_type_is_scalar_struct(log, btf, member_type, rec + 1)) + return false; + continue; + } + if (btf_type_is_array(member_type)) { + array = btf_type_array(member_type); + if (!array->nelems) + return false; + member_type = btf_type_skip_modifiers(btf, array->type, NULL); + if (!btf_type_is_scalar(member_type)) + return false; + continue; + } + if (!btf_type_is_scalar(member_type)) + return false; + } + return true; +} + static int btf_check_func_arg_match(struct bpf_verifier_env *env, const struct btf *btf, u32 func_id, struct bpf_reg_state *regs, bool ptr_to_mem_ok) { struct bpf_verifier_log *log = &env->log; + bool is_kfunc = btf_is_kernel(btf); const char *func_name, *ref_tname; const struct btf_type *t, *ref_t; const struct btf_param *args; @@ -5634,7 +5675,20 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id); ref_tname = btf_name_by_offset(btf, ref_t->name_off); - if (btf_is_kernel(btf)) { + if (btf_get_prog_ctx_type(log, btf, t, + env->prog->type, i)) { + /* If function expects ctx type in BTF check that caller + * is passing PTR_TO_CTX. + */ + if (reg->type != PTR_TO_CTX) { + bpf_log(log, + "arg#%d expected pointer to ctx, but got %s\n", + i, btf_type_str(t)); + return -EINVAL; + } + if (check_ctx_reg(env, reg, regno)) + return -EINVAL; + } else if (is_kfunc && (reg->type == PTR_TO_BTF_ID || reg2btf_ids[reg->type])) { const struct btf_type *reg_ref_t; const struct btf *reg_btf; const char *reg_ref_tname; @@ -5650,14 +5704,9 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, if (reg->type == PTR_TO_BTF_ID) { reg_btf = reg->btf; reg_ref_id = reg->btf_id; - } else if (reg2btf_ids[reg->type]) { + } else { reg_btf = btf_vmlinux; reg_ref_id = *reg2btf_ids[reg->type]; - } else { - bpf_log(log, "kernel function %s args#%d expected pointer to %s %s but R%d is not a pointer to btf_id\n", - func_name, i, - btf_type_str(ref_t), ref_tname, regno); - return -EINVAL; } reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, @@ -5673,23 +5722,24 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, reg_ref_tname); return -EINVAL; } - } else if (btf_get_prog_ctx_type(log, btf, t, - env->prog->type, i)) { - /* If function expects ctx type in BTF check that caller - * is passing PTR_TO_CTX. - */ - if (reg->type != PTR_TO_CTX) { - bpf_log(log, - "arg#%d expected pointer to ctx, but got %s\n", - i, btf_type_str(t)); - return -EINVAL; - } - if (check_ctx_reg(env, reg, regno)) - return -EINVAL; } else if (ptr_to_mem_ok) { const struct btf_type *resolve_ret; u32 type_size; + if (is_kfunc) { + /* Permit pointer to mem, but only when argument + * type is pointer to scalar, or struct composed + * (recursively) of scalars. + */ + if (!btf_type_is_scalar(ref_t) && + !__btf_type_is_scalar_struct(log, btf, ref_t, 0)) { + bpf_log(log, + "arg#%d pointer type %s %s must point to scalar or struct with scalar\n", + i, btf_type_str(ref_t), ref_tname); + return -EINVAL; + } + } + resolve_ret = btf_resolve_size(btf, ref_t, &type_size); if (IS_ERR(resolve_ret)) { bpf_log(log, @@ -5702,6 +5752,8 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, if (check_mem_reg(env, reg, regno, type_size)) return -EINVAL; } else { + bpf_log(log, "reg type unsupported for arg#%d %sfunction %s#%d\n", i, + is_kfunc ? "kernel " : "", func_name, func_id); return -EINVAL; } } @@ -5751,7 +5803,7 @@ int btf_check_kfunc_arg_match(struct bpf_verifier_env *env, const struct btf *btf, u32 func_id, struct bpf_reg_state *regs) { - return btf_check_func_arg_match(env, btf, func_id, regs, false); + return btf_check_func_arg_match(env, btf, func_id, regs, true); } /* Convert BTF of a function into bpf_reg_state if possible |