diff options
Diffstat (limited to 'kernel/bpf/btf.c')
| -rw-r--r-- | kernel/bpf/btf.c | 244 |
1 files changed, 243 insertions, 1 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index f25bca59909d..74037bd65d17 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -198,6 +198,21 @@ DEFINE_IDR(btf_idr); DEFINE_SPINLOCK(btf_idr_lock); +enum btf_kfunc_hook { + BTF_KFUNC_HOOK_XDP, + BTF_KFUNC_HOOK_TC, + BTF_KFUNC_HOOK_STRUCT_OPS, + BTF_KFUNC_HOOK_MAX, +}; + +enum { + BTF_KFUNC_SET_MAX_CNT = 32, +}; + +struct btf_kfunc_set_tab { + struct btf_id_set *sets[BTF_KFUNC_HOOK_MAX][BTF_KFUNC_TYPE_MAX]; +}; + struct btf { void *data; struct btf_type **types; @@ -212,6 +227,7 @@ struct btf { refcount_t refcnt; u32 id; struct rcu_head rcu; + struct btf_kfunc_set_tab *kfunc_set_tab; /* split BTF support */ struct btf *base_btf; @@ -1531,8 +1547,30 @@ static void btf_free_id(struct btf *btf) spin_unlock_irqrestore(&btf_idr_lock, flags); } +static void btf_free_kfunc_set_tab(struct btf *btf) +{ + struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab; + int hook, type; + + if (!tab) + return; + /* For module BTF, we directly assign the sets being registered, so + * there is nothing to free except kfunc_set_tab. + */ + if (btf_is_module(btf)) + goto free_tab; + for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++) { + for (type = 0; type < ARRAY_SIZE(tab->sets[0]); type++) + kfree(tab->sets[hook][type]); + } +free_tab: + kfree(tab); + btf->kfunc_set_tab = NULL; +} + static void btf_free(struct btf *btf) { + btf_free_kfunc_set_tab(btf); kvfree(btf->types); kvfree(btf->resolved_sizes); kvfree(btf->resolved_ids); @@ -6371,6 +6409,36 @@ struct module *btf_try_get_module(const struct btf *btf) return res; } +/* Returns struct btf corresponding to the struct module + * + * This function can return NULL or ERR_PTR. Note that caller must + * release reference for struct btf iff btf_is_module is true. + */ +static struct btf *btf_get_module_btf(const struct module *module) +{ + struct btf *btf = NULL; +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + struct btf_module *btf_mod, *tmp; +#endif + + if (!module) + return bpf_get_btf_vmlinux(); +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + mutex_lock(&btf_module_mutex); + list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) { + if (btf_mod->module != module) + continue; + + btf_get(btf_mod->btf); + btf = btf_mod->btf; + break; + } + mutex_unlock(&btf_module_mutex); +#endif + + return btf; +} + BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags) { struct btf *btf; @@ -6438,7 +6506,181 @@ BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE) BTF_TRACING_TYPE_xxx #undef BTF_TRACING_TYPE -/* BTF ID set registration API for modules */ +/* Kernel Function (kfunc) BTF ID set registration API */ + +static int __btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook, + enum btf_kfunc_type type, + struct btf_id_set *add_set, bool vmlinux_set) +{ + struct btf_kfunc_set_tab *tab; + struct btf_id_set *set; + u32 set_cnt; + int ret; + + if (hook >= BTF_KFUNC_HOOK_MAX || type >= BTF_KFUNC_TYPE_MAX) { + ret = -EINVAL; + goto end; + } + + if (!add_set->cnt) + return 0; + + tab = btf->kfunc_set_tab; + if (!tab) { + tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN); + if (!tab) + return -ENOMEM; + btf->kfunc_set_tab = tab; + } + + set = tab->sets[hook][type]; + /* Warn when register_btf_kfunc_id_set is called twice for the same hook + * for module sets. + */ + if (WARN_ON_ONCE(set && !vmlinux_set)) { + ret = -EINVAL; + goto end; + } + + /* We don't need to allocate, concatenate, and sort module sets, because + * only one is allowed per hook. Hence, we can directly assign the + * pointer and return. + */ + if (!vmlinux_set) { + tab->sets[hook][type] = add_set; + return 0; + } + + /* In case of vmlinux sets, there may be more than one set being + * registered per hook. To create a unified set, we allocate a new set + * and concatenate all individual sets being registered. While each set + * is individually sorted, they may become unsorted when concatenated, + * hence re-sorting the final set again is required to make binary + * searching the set using btf_id_set_contains function work. + */ + set_cnt = set ? set->cnt : 0; + + if (set_cnt > U32_MAX - add_set->cnt) { + ret = -EOVERFLOW; + goto end; + } + + if (set_cnt + add_set->cnt > BTF_KFUNC_SET_MAX_CNT) { + ret = -E2BIG; + goto end; + } + + /* Grow set */ + set = krealloc(tab->sets[hook][type], + offsetof(struct btf_id_set, ids[set_cnt + add_set->cnt]), + GFP_KERNEL | __GFP_NOWARN); + if (!set) { + ret = -ENOMEM; + goto end; + } + + /* For newly allocated set, initialize set->cnt to 0 */ + if (!tab->sets[hook][type]) + set->cnt = 0; + tab->sets[hook][type] = set; + + /* Concatenate the two sets */ + memcpy(set->ids + set->cnt, add_set->ids, add_set->cnt * sizeof(set->ids[0])); + set->cnt += add_set->cnt; + + sort(set->ids, set->cnt, sizeof(set->ids[0]), btf_id_cmp_func, NULL); + + return 0; +end: + btf_free_kfunc_set_tab(btf); + return ret; +} + +static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook, + const struct btf_kfunc_id_set *kset) +{ + bool vmlinux_set = !btf_is_module(btf); + int type, ret; + + for (type = 0; type < ARRAY_SIZE(kset->sets); type++) { + if (!kset->sets[type]) + continue; + + ret = __btf_populate_kfunc_set(btf, hook, type, kset->sets[type], vmlinux_set); + if (ret) + break; + } + return ret; +} + +static bool __btf_kfunc_id_set_contains(const struct btf *btf, + enum btf_kfunc_hook hook, + enum btf_kfunc_type type, + u32 kfunc_btf_id) +{ + struct btf_id_set *set; + + if (hook >= BTF_KFUNC_HOOK_MAX || type >= BTF_KFUNC_TYPE_MAX) + return false; + if (!btf->kfunc_set_tab) + return false; + set = btf->kfunc_set_tab->sets[hook][type]; + if (!set) + return false; + return btf_id_set_contains(set, kfunc_btf_id); +} + +static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type) +{ + switch (prog_type) { + case BPF_PROG_TYPE_XDP: + return BTF_KFUNC_HOOK_XDP; + case BPF_PROG_TYPE_SCHED_CLS: + return BTF_KFUNC_HOOK_TC; + case BPF_PROG_TYPE_STRUCT_OPS: + return BTF_KFUNC_HOOK_STRUCT_OPS; + default: + return BTF_KFUNC_HOOK_MAX; + } +} + +/* Caution: + * Reference to the module (obtained using btf_try_get_module) corresponding to + * the struct btf *MUST* be held when calling this function from verifier + * context. This is usually true as we stash references in prog's kfunc_btf_tab; + * keeping the reference for the duration of the call provides the necessary + * protection for looking up a well-formed btf->kfunc_set_tab. + */ +bool btf_kfunc_id_set_contains(const struct btf *btf, + enum bpf_prog_type prog_type, + enum btf_kfunc_type type, u32 kfunc_btf_id) +{ + enum btf_kfunc_hook hook; + + hook = bpf_prog_type_to_kfunc_hook(prog_type); + return __btf_kfunc_id_set_contains(btf, hook, type, kfunc_btf_id); +} + +/* This function must be invoked only from initcalls/module init functions */ +int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, + const struct btf_kfunc_id_set *kset) +{ + enum btf_kfunc_hook hook; + struct btf *btf; + int ret; + + btf = btf_get_module_btf(kset->owner); + if (IS_ERR_OR_NULL(btf)) + return btf ? PTR_ERR(btf) : -ENOENT; + + hook = bpf_prog_type_to_kfunc_hook(prog_type); + ret = btf_populate_kfunc_set(btf, hook, kset); + /* reference is only taken for module BTF */ + if (btf_is_module(btf)) + btf_put(btf); + return ret; +} +EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set); #ifdef CONFIG_DEBUG_INFO_BTF_MODULES |