diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ba09795e0bfd..adf53f7edf28 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3146,7 +3146,7 @@ int btf_struct_access(struct bpf_verifier_log *log, bool btf_struct_ids_match(struct bpf_verifier_log *log, const struct btf *btf, u32 id, int off, const struct btf *need_btf, u32 need_type_id, - bool strict); + bool strict, bool walk_flex_arrays); int btf_distill_func_proto(struct bpf_verifier_log *log, struct btf *btf, diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 64572f85edc8..dff5c0d91641 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7108,7 +7108,7 @@ enum bpf_struct_walk_result { static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf, const struct btf_type *t, int off, int size, u32 *next_btf_id, enum bpf_type_flag *flag, - const char **field_name) + const char **field_name, bool walk_flex_arrays) { u32 i, moff, mtrue_end, msize = 0, total_nelems = 0; const struct btf_type *mtype, *elem_type = NULL; @@ -7135,11 +7135,14 @@ static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf, *flag |= PTR_UNTRUSTED; if (off + size > t->size) { + struct btf_array *array_elem; + + if (!walk_flex_arrays) + goto error; + /* If the last element is a variable size array, we may * need to relax the rule. */ - struct btf_array *array_elem; - if (vlen == 0) goto error; @@ -7404,7 +7407,8 @@ int btf_struct_access(struct bpf_verifier_log *log, t = btf_type_by_id(btf, id); do { - err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag, field_name); + err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag, + field_name, !type_is_alloc(reg->type)); switch (err) { case WALK_PTR: @@ -7463,7 +7467,7 @@ bool btf_types_are_same(const struct btf *btf1, u32 id1, bool btf_struct_ids_match(struct bpf_verifier_log *log, const struct btf *btf, u32 id, int off, const struct btf *need_btf, u32 need_type_id, - bool strict) + bool strict, bool walk_flex_arrays) { const struct btf_type *type; enum bpf_type_flag flag = 0; @@ -7482,7 +7486,8 @@ bool btf_struct_ids_match(struct bpf_verifier_log *log, type = btf_type_by_id(btf, id); if (!type) return false; - err = btf_struct_walk(log, btf, type, off, 1, &id, &flag, NULL); + err = btf_struct_walk(log, btf, type, off, 1, &id, &flag, NULL, + walk_flex_arrays); if (err != WALK_STRUCT) return false; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d46f7db20d8f..a0f292635c59 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4379,7 +4379,8 @@ static int map_kptr_match_type(struct bpf_verifier_env *env, */ if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->var_off.value, kptr_field->kptr.btf, kptr_field->kptr.btf_id, - kptr_field->type != BPF_KPTR_UNREF)) + kptr_field->type != BPF_KPTR_UNREF, + !type_is_alloc(reg->type))) goto bad_type; return 0; bad_type: @@ -7970,7 +7971,7 @@ static int check_reg_type(struct bpf_verifier_env *env, struct bpf_reg_state *re if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->var_off.value, btf_vmlinux, *arg_btf_id, - strict_type_match)) { + strict_type_match, !type_is_alloc(reg->type))) { verbose(env, "%s is of type %s but %s is expected\n", reg_arg_name(env, argno), btf_type_name(reg->btf, reg->btf_id), @@ -11436,7 +11437,8 @@ static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env, reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, ®_ref_id); reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off); struct_same = btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->var_off.value, - meta->btf, ref_id, strict_type_match); + meta->btf, ref_id, strict_type_match, + !type_is_alloc(reg->type)); /* If kfunc is accepting a projection type (ie. __sk_buff), it cannot * actually use it -- it must cast to the underlying type. So we allow * caller to pass in the underlying type. @@ -11883,7 +11885,8 @@ __process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env, et = btf_type_by_id(field->graph_root.btf, field->graph_root.value_btf_id); t = btf_type_by_id(reg->btf, reg->btf_id); if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, 0, field->graph_root.btf, - field->graph_root.value_btf_id, true)) { + field->graph_root.value_btf_id, true, + !type_is_alloc(reg->type))) { verbose(env, "operation on %s expects arg#1 %s at offset=%d " "in struct %s, but arg is at offset=%d in struct %s\n", btf_field_type_name(head_field_type), diff --git a/tools/testing/selftests/bpf/prog_tests/linked_list.c b/tools/testing/selftests/bpf/prog_tests/linked_list.c index 8defea0253ed..c3d133c6a00d 100644 --- a/tools/testing/selftests/bpf/prog_tests/linked_list.c +++ b/tools/testing/selftests/bpf/prog_tests/linked_list.c @@ -68,6 +68,7 @@ static struct { { "obj_type_id_oor", "local type ID argument must be in range [0, U32_MAX]" }, { "obj_new_no_composite", "bpf_obj_new/bpf_percpu_obj_new type ID argument must be of a struct" }, { "obj_new_no_struct", "bpf_obj_new/bpf_percpu_obj_new type ID argument must be of a struct" }, + { "obj_new_flex_array", "access beyond struct obj_new_flex" }, { "obj_drop_non_zero_off", "R1 must have zero offset when passed to release func" }, { "new_null_ret", "R0 invalid mem access 'ptr_or_null_'" }, { "obj_new_acq", "Unreleased reference id=" }, diff --git a/tools/testing/selftests/bpf/progs/linked_list_fail.c b/tools/testing/selftests/bpf/progs/linked_list_fail.c index ddd26d1a083f..031e77a288ee 100644 --- a/tools/testing/selftests/bpf/progs/linked_list_fail.c +++ b/tools/testing/selftests/bpf/progs/linked_list_fail.c @@ -167,6 +167,16 @@ CHECK_OP(push_back); #undef CHECK_OP #undef INIT +struct obj_new_flex_elem { + int lo; + int hi; +}; + +struct obj_new_flex { + int hdr; + struct obj_new_flex_elem cells[]; +}; + SEC("?kprobe/xyz") int map_compat_kprobe(void *ctx) { @@ -230,6 +240,19 @@ int obj_new_no_struct(void *ctx) return 0; } +SEC("?tc") +int obj_new_flex_array(void *ctx) +{ + struct obj_new_flex *p; + + p = bpf_obj_new_impl(bpf_core_type_id_local(struct obj_new_flex), NULL); + if (!p) + return 0; + p->cells[0].hi = 42; + bpf_obj_drop_impl(p, NULL); + return 0; +} + SEC("?tc") int obj_drop_non_zero_off(void *ctx) {