diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 0ef00f7f64c9..db13ee70d94d 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -390,7 +390,7 @@ int bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc, st_ops_desc->value_type = btf_type_by_id(btf, value_id); for_each_member(i, t, member) { - const struct btf_type *func_proto; + const struct btf_type *func_proto, *ret_type; void **stub_func_addr; u32 moff; @@ -427,6 +427,16 @@ int bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc, if (!func_proto || bpf_struct_ops_supported(st_ops, moff)) continue; + if (func_proto->type) { + ret_type = btf_type_resolve_ptr(btf, func_proto->type, NULL); + if (ret_type && !__btf_type_is_struct(ret_type)) { + pr_warn("func ptr %s in struct %s returns non-struct pointer, which is not supported\n", + mname, st_ops->name); + err = -EOPNOTSUPP; + goto errout; + } + } + if (btf_distill_func_proto(log, btf, func_proto, mname, &st_ops->func_models[i])) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c2762b56e604..e7bc74171c99 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10758,6 +10758,8 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exit) { struct bpf_verifier_state *state = env->cur_state; + enum bpf_prog_type type = resolve_prog_type(env->prog); + struct bpf_reg_state *reg = reg_state(env, BPF_REG_0); bool refs_lingering = false; int i; @@ -10767,6 +10769,12 @@ static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exi for (i = 0; i < state->acquired_refs; i++) { if (state->refs[i].type != REF_TYPE_PTR) continue; + /* Allow struct_ops programs to return a referenced kptr back to + * kernel. Type checks are performed later in check_return_code. + */ + if (type == BPF_PROG_TYPE_STRUCT_OPS && !exception_exit && + reg->ref_obj_id == state->refs[i].id) + continue; verbose(env, "Unreleased reference id=%d alloc_insn=%d\n", state->refs[i].id, state->refs[i].insn_idx); refs_lingering = true; @@ -16418,13 +16426,14 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char const char *exit_ctx = "At program exit"; struct tnum enforce_attach_type_range = tnum_unknown; const struct bpf_prog *prog = env->prog; - struct bpf_reg_state *reg; + struct bpf_reg_state *reg = reg_state(env, regno); struct bpf_retval_range range = retval_range(0, 1); enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; struct bpf_func_state *frame = env->cur_state->frame[0]; const bool is_subprog = frame->subprogno; bool return_32bit = false; + const struct btf_type *reg_type, *ret_type = NULL; /* LSM and struct_ops func-ptr's return type could be "void" */ if (!is_subprog || frame->in_exception_callback_fn) { @@ -16433,10 +16442,26 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char if (prog->expected_attach_type == BPF_LSM_CGROUP) /* See below, can be 0 or 0-1 depending on hook. */ break; - fallthrough; + if (!prog->aux->attach_func_proto->type) + return 0; + break; case BPF_PROG_TYPE_STRUCT_OPS: if (!prog->aux->attach_func_proto->type) return 0; + + if (frame->in_exception_callback_fn) + break; + + /* Allow a struct_ops program to return a referenced kptr if it + * matches the operator's return type and is in its unmodified + * form. A scalar zero (i.e., a null pointer) is also allowed. + */ + reg_type = reg->btf ? btf_type_by_id(reg->btf, reg->btf_id) : NULL; + ret_type = btf_type_resolve_ptr(prog->aux->attach_btf, + prog->aux->attach_func_proto->type, + NULL); + if (ret_type && ret_type == reg_type && reg->ref_obj_id) + return __check_ptr_off_reg(env, reg, regno, false); break; default: break; @@ -16458,8 +16483,6 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char return -EACCES; } - reg = cur_regs(env) + regno; - if (frame->in_async_callback_fn) { /* enforce return zero from async callbacks like timer */ exit_ctx = "At async callback return"; @@ -16558,6 +16581,11 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char case BPF_PROG_TYPE_NETFILTER: range = retval_range(NF_DROP, NF_ACCEPT); break; + case BPF_PROG_TYPE_STRUCT_OPS: + if (!ret_type) + return 0; + range = retval_range(0, 0); + break; case BPF_PROG_TYPE_EXT: /* freplace program can return anything as its return value * depends on the to-be-replaced kernel func or bpf program.