diff options
Diffstat (limited to 'kernel/bpf/btf.c')
| -rw-r--r-- | kernel/bpf/btf.c | 98 |
1 files changed, 97 insertions, 1 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index a0b1665a4a48..1f2012fd89fb 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3416,6 +3416,7 @@ struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf, struct btf_field_info info_arr[BPF_MAP_VALUE_OFF_MAX]; struct bpf_map_value_off *tab; struct btf *kernel_btf = NULL; + struct module *mod = NULL; int ret, i, nr_off; ret = btf_find_field(btf, t, BTF_FIELD_KPTR, info_arr, ARRAY_SIZE(info_arr)); @@ -3444,16 +3445,69 @@ struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf, goto end; } + /* Find and stash the function pointer for the destruction function that + * needs to be eventually invoked from the map free path. + */ + if (info_arr[i].type == BPF_KPTR_REF) { + const struct btf_type *dtor_func; + const char *dtor_func_name; + unsigned long addr; + s32 dtor_btf_id; + + /* This call also serves as a whitelist of allowed objects that + * can be used as a referenced pointer and be stored in a map at + * the same time. + */ + dtor_btf_id = btf_find_dtor_kfunc(kernel_btf, id); + if (dtor_btf_id < 0) { + ret = dtor_btf_id; + goto end_btf; + } + + dtor_func = btf_type_by_id(kernel_btf, dtor_btf_id); + if (!dtor_func) { + ret = -ENOENT; + goto end_btf; + } + + if (btf_is_module(kernel_btf)) { + mod = btf_try_get_module(kernel_btf); + if (!mod) { + ret = -ENXIO; + goto end_btf; + } + } + + /* We already verified dtor_func to be btf_type_is_func + * in register_btf_id_dtor_kfuncs. + */ + dtor_func_name = __btf_name_by_offset(kernel_btf, dtor_func->name_off); + addr = kallsyms_lookup_name(dtor_func_name); + if (!addr) { + ret = -EINVAL; + goto end_mod; + } + tab->off[i].kptr.dtor = (void *)addr; + } + tab->off[i].offset = info_arr[i].off; tab->off[i].type = info_arr[i].type; tab->off[i].kptr.btf_id = id; tab->off[i].kptr.btf = kernel_btf; + tab->off[i].kptr.module = mod; } tab->nr_off = nr_off; return tab; +end_mod: + module_put(mod); +end_btf: + btf_put(kernel_btf); end: - while (i--) + while (i--) { btf_put(tab->off[i].kptr.btf); + if (tab->off[i].kptr.module) + module_put(tab->off[i].kptr.module); + } kfree(tab); return ERR_PTR(ret); } @@ -7111,6 +7165,43 @@ s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id) return dtor->kfunc_btf_id; } +static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc *dtors, u32 cnt) +{ + const struct btf_type *dtor_func, *dtor_func_proto, *t; + const struct btf_param *args; + s32 dtor_btf_id; + u32 nr_args, i; + + for (i = 0; i < cnt; i++) { + dtor_btf_id = dtors[i].kfunc_btf_id; + + dtor_func = btf_type_by_id(btf, dtor_btf_id); + if (!dtor_func || !btf_type_is_func(dtor_func)) + return -EINVAL; + + dtor_func_proto = btf_type_by_id(btf, dtor_func->type); + if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto)) + return -EINVAL; + + /* Make sure the prototype of the destructor kfunc is 'void func(type *)' */ + t = btf_type_by_id(btf, dtor_func_proto->type); + if (!t || !btf_type_is_void(t)) + return -EINVAL; + + nr_args = btf_type_vlen(dtor_func_proto); + if (nr_args != 1) + return -EINVAL; + args = btf_params(dtor_func_proto); + t = btf_type_by_id(btf, args[0].type); + /* Allow any pointer type, as width on targets Linux supports + * will be same for all pointer types (i.e. sizeof(void *)) + */ + if (!t || !btf_type_is_ptr(t)) + return -EINVAL; + } + return 0; +} + /* This function must be invoked only from initcalls/module init functions */ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt, struct module *owner) @@ -7141,6 +7232,11 @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c goto end; } + /* Ensure that the prototype of dtor kfuncs being registered is sane */ + ret = btf_check_dtor_kfuncs(btf, dtors, add_cnt); + if (ret < 0) + goto end; + tab = btf->dtor_kfunc_tab; /* Only one call allowed for modules */ if (WARN_ON_ONCE(tab && btf_is_module(btf))) { |