diff options
Diffstat (limited to 'kernel/bpf/btf.c')
-rw-r--r-- | kernel/bpf/btf.c | 640 |
1 files changed, 554 insertions, 86 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 0918a39279f6..7bccaa4646e5 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -202,17 +202,25 @@ enum btf_kfunc_hook { BTF_KFUNC_HOOK_XDP, BTF_KFUNC_HOOK_TC, BTF_KFUNC_HOOK_STRUCT_OPS, + BTF_KFUNC_HOOK_TRACING, + BTF_KFUNC_HOOK_SYSCALL, BTF_KFUNC_HOOK_MAX, }; enum { BTF_KFUNC_SET_MAX_CNT = 32, + BTF_DTOR_KFUNC_MAX_CNT = 256, }; struct btf_kfunc_set_tab { struct btf_id_set *sets[BTF_KFUNC_HOOK_MAX][BTF_KFUNC_TYPE_MAX]; }; +struct btf_id_dtor_kfunc_tab { + u32 cnt; + struct btf_id_dtor_kfunc dtors[]; +}; + struct btf { void *data; struct btf_type **types; @@ -228,6 +236,7 @@ struct btf { u32 id; struct rcu_head rcu; struct btf_kfunc_set_tab *kfunc_set_tab; + struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab; /* split BTF support */ struct btf *base_btf; @@ -1616,8 +1625,19 @@ free_tab: btf->kfunc_set_tab = NULL; } +static void btf_free_dtor_kfunc_tab(struct btf *btf) +{ + struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab; + + if (!tab) + return; + kfree(tab); + btf->dtor_kfunc_tab = NULL; +} + static void btf_free(struct btf *btf) { + btf_free_dtor_kfunc_tab(btf); btf_free_kfunc_set_tab(btf); kvfree(btf->types); kvfree(btf->resolved_sizes); @@ -3163,24 +3183,86 @@ static void btf_struct_log(struct btf_verifier_env *env, btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t)); } +enum btf_field_type { + BTF_FIELD_SPIN_LOCK, + BTF_FIELD_TIMER, + BTF_FIELD_KPTR, +}; + +enum { + BTF_FIELD_IGNORE = 0, + BTF_FIELD_FOUND = 1, +}; + +struct btf_field_info { + u32 type_id; + u32 off; + enum bpf_kptr_type type; +}; + +static int btf_find_struct(const struct btf *btf, const struct btf_type *t, + u32 off, int sz, struct btf_field_info *info) +{ + if (!__btf_type_is_struct(t)) + return BTF_FIELD_IGNORE; + if (t->size != sz) + return BTF_FIELD_IGNORE; + info->off = off; + return BTF_FIELD_FOUND; +} + +static int btf_find_kptr(const struct btf *btf, const struct btf_type *t, + u32 off, int sz, struct btf_field_info *info) +{ + enum bpf_kptr_type type; + u32 res_id; + + /* For PTR, sz is always == 8 */ + if (!btf_type_is_ptr(t)) + return BTF_FIELD_IGNORE; + t = btf_type_by_id(btf, t->type); + + if (!btf_type_is_type_tag(t)) + return BTF_FIELD_IGNORE; + /* Reject extra tags */ + if (btf_type_is_type_tag(btf_type_by_id(btf, t->type))) + return -EINVAL; + if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off))) + type = BPF_KPTR_UNREF; + else if (!strcmp("kptr_ref", __btf_name_by_offset(btf, t->name_off))) + type = BPF_KPTR_REF; + else + return -EINVAL; + + /* Get the base type */ + t = btf_type_skip_modifiers(btf, t->type, &res_id); + /* Only pointer to struct is allowed */ + if (!__btf_type_is_struct(t)) + return -EINVAL; + + info->type_id = res_id; + info->off = off; + info->type = type; + return BTF_FIELD_FOUND; +} + static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t, - const char *name, int sz, int align) + const char *name, int sz, int align, + enum btf_field_type field_type, + struct btf_field_info *info, int info_cnt) { const struct btf_member *member; - u32 i, off = -ENOENT; + struct btf_field_info tmp; + int ret, idx = 0; + u32 i, off; for_each_member(i, t, member) { const struct btf_type *member_type = btf_type_by_id(btf, member->type); - if (!__btf_type_is_struct(member_type)) - continue; - if (member_type->size != sz) - continue; - if (strcmp(__btf_name_by_offset(btf, member_type->name_off), name)) + + if (name && strcmp(__btf_name_by_offset(btf, member_type->name_off), name)) continue; - if (off != -ENOENT) - /* only one such field is allowed */ - return -E2BIG; + off = __btf_member_bit_offset(t, member); if (off % 8) /* valid C code cannot generate such BTF */ @@ -3188,46 +3270,115 @@ static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t off /= 8; if (off % align) return -EINVAL; + + switch (field_type) { + case BTF_FIELD_SPIN_LOCK: + case BTF_FIELD_TIMER: + ret = btf_find_struct(btf, member_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + case BTF_FIELD_KPTR: + ret = btf_find_kptr(btf, member_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + default: + return -EFAULT; + } + + if (ret == BTF_FIELD_IGNORE) + continue; + if (idx >= info_cnt) + return -E2BIG; + ++idx; } - return off; + return idx; } static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t, - const char *name, int sz, int align) + const char *name, int sz, int align, + enum btf_field_type field_type, + struct btf_field_info *info, int info_cnt) { const struct btf_var_secinfo *vsi; - u32 i, off = -ENOENT; + struct btf_field_info tmp; + int ret, idx = 0; + u32 i, off; for_each_vsi(i, t, vsi) { const struct btf_type *var = btf_type_by_id(btf, vsi->type); const struct btf_type *var_type = btf_type_by_id(btf, var->type); - if (!__btf_type_is_struct(var_type)) - continue; - if (var_type->size != sz) + off = vsi->offset; + + if (name && strcmp(__btf_name_by_offset(btf, var_type->name_off), name)) continue; if (vsi->size != sz) continue; - if (strcmp(__btf_name_by_offset(btf, var_type->name_off), name)) - continue; - if (off != -ENOENT) - /* only one such field is allowed */ - return -E2BIG; - off = vsi->offset; if (off % align) return -EINVAL; + + switch (field_type) { + case BTF_FIELD_SPIN_LOCK: + case BTF_FIELD_TIMER: + ret = btf_find_struct(btf, var_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + case BTF_FIELD_KPTR: + ret = btf_find_kptr(btf, var_type, off, sz, + idx < info_cnt ? &info[idx] : &tmp); + if (ret < 0) + return ret; + break; + default: + return -EFAULT; + } + + if (ret == BTF_FIELD_IGNORE) + continue; + if (idx >= info_cnt) + return -E2BIG; + ++idx; } - return off; + return idx; } static int btf_find_field(const struct btf *btf, const struct btf_type *t, - const char *name, int sz, int align) + enum btf_field_type field_type, + struct btf_field_info *info, int info_cnt) { + const char *name; + int sz, align; + + switch (field_type) { + case BTF_FIELD_SPIN_LOCK: + name = "bpf_spin_lock"; + sz = sizeof(struct bpf_spin_lock); + align = __alignof__(struct bpf_spin_lock); + break; + case BTF_FIELD_TIMER: + name = "bpf_timer"; + sz = sizeof(struct bpf_timer); + align = __alignof__(struct bpf_timer); + break; + case BTF_FIELD_KPTR: + name = NULL; + sz = sizeof(u64); + align = 8; + break; + default: + return -EFAULT; + } if (__btf_type_is_struct(t)) - return btf_find_struct_field(btf, t, name, sz, align); + return btf_find_struct_field(btf, t, name, sz, align, field_type, info, info_cnt); else if (btf_type_is_datasec(t)) - return btf_find_datasec_var(btf, t, name, sz, align); + return btf_find_datasec_var(btf, t, name, sz, align, field_type, info, info_cnt); return -EINVAL; } @@ -3237,16 +3388,130 @@ static int btf_find_field(const struct btf *btf, const struct btf_type *t, */ int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t) { - return btf_find_field(btf, t, "bpf_spin_lock", - sizeof(struct bpf_spin_lock), - __alignof__(struct bpf_spin_lock)); + struct btf_field_info info; + int ret; + + ret = btf_find_field(btf, t, BTF_FIELD_SPIN_LOCK, &info, 1); + if (ret < 0) + return ret; + if (!ret) + return -ENOENT; + return info.off; } int btf_find_timer(const struct btf *btf, const struct btf_type *t) { - return btf_find_field(btf, t, "bpf_timer", - sizeof(struct bpf_timer), - __alignof__(struct bpf_timer)); + struct btf_field_info info; + int ret; + + ret = btf_find_field(btf, t, BTF_FIELD_TIMER, &info, 1); + if (ret < 0) + return ret; + if (!ret) + return -ENOENT; + return info.off; +} + +struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf, + const struct btf_type *t) +{ + 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)); + if (ret < 0) + return ERR_PTR(ret); + if (!ret) + return NULL; + + nr_off = ret; + tab = kzalloc(offsetof(struct bpf_map_value_off, off[nr_off]), GFP_KERNEL | __GFP_NOWARN); + if (!tab) + return ERR_PTR(-ENOMEM); + + for (i = 0; i < nr_off; i++) { + const struct btf_type *t; + s32 id; + + /* Find type in map BTF, and use it to look up the matching type + * in vmlinux or module BTFs, by name and kind. + */ + t = btf_type_by_id(btf, info_arr[i].type_id); + id = bpf_find_btf_id(__btf_name_by_offset(btf, t->name_off), BTF_INFO_KIND(t->info), + &kernel_btf); + if (id < 0) { + ret = id; + 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--) { + 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); } static void __btf_struct_show(const struct btf *btf, const struct btf_type *t, @@ -4541,6 +4806,48 @@ static int btf_parse_hdr(struct btf_verifier_env *env) return 0; } +static int btf_check_type_tags(struct btf_verifier_env *env, + struct btf *btf, int start_id) +{ + int i, n, good_id = start_id - 1; + bool in_tags; + + n = btf_nr_types(btf); + for (i = start_id; i < n; i++) { + const struct btf_type *t; + u32 cur_id = i; + + t = btf_type_by_id(btf, i); + if (!t) + return -EINVAL; + if (!btf_type_is_modifier(t)) + continue; + + cond_resched(); + + in_tags = btf_type_is_type_tag(t); + while (btf_type_is_modifier(t)) { + if (btf_type_is_type_tag(t)) { + if (!in_tags) { + btf_verifier_log(env, "Type tags don't precede modifiers"); + return -EINVAL; + } + } else if (in_tags) { + in_tags = false; + } + if (cur_id <= good_id) + break; + /* Move to next type */ + cur_id = t->type; + t = btf_type_by_id(btf, cur_id); + if (!t) + return -EINVAL; + } + good_id = i; + } + return 0; +} + static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size, u32 log_level, char __user *log_ubuf, u32 log_size) { @@ -4608,6 +4915,10 @@ static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size, if (err) goto errout; + err = btf_check_type_tags(env, btf, 1); + if (err) + goto errout; + if (log->level && bpf_verifier_log_full(log)) { err = -ENOSPC; goto errout; @@ -4716,41 +5027,6 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, return ctx_type; } -static const struct bpf_map_ops * const btf_vmlinux_map_ops[] = { -#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) -#define BPF_LINK_TYPE(_id, _name) -#define BPF_MAP_TYPE(_id, _ops) \ - [_id] = &_ops, -#include <linux/bpf_types.h> -#undef BPF_PROG_TYPE -#undef BPF_LINK_TYPE -#undef BPF_MAP_TYPE -}; - -static int btf_vmlinux_map_ids_init(const struct btf *btf, - struct bpf_verifier_log *log) -{ - const struct bpf_map_ops *ops; - int i, btf_id; - - for (i = 0; i < ARRAY_SIZE(btf_vmlinux_map_ops); ++i) { - ops = btf_vmlinux_map_ops[i]; - if (!ops || (!ops->map_btf_name && !ops->map_btf_id)) - continue; - if (!ops->map_btf_name || !ops->map_btf_id) { - bpf_log(log, "map type %d is misconfigured\n", i); - return -EINVAL; - } - btf_id = btf_find_by_name_kind(btf, ops->map_btf_name, - BTF_KIND_STRUCT); - if (btf_id < 0) - return btf_id; - *ops->map_btf_id = btf_id; - } - - return 0; -} - static int btf_translate_to_vmlinux(struct bpf_verifier_log *log, struct btf *btf, const struct btf_type *t, @@ -4809,14 +5085,13 @@ struct btf *btf_parse_vmlinux(void) if (err) goto errout; + err = btf_check_type_tags(env, btf, 1); + if (err) + goto errout; + /* btf_parse_vmlinux() runs under bpf_verifier_lock */ bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]); - /* find bpf map structs for map_ptr access checking */ - err = btf_vmlinux_map_ids_init(btf, log); - if (err < 0) - goto errout; - bpf_struct_ops_init(btf, log); refcount_set(&btf->refcnt, 1); @@ -4894,6 +5169,10 @@ static struct btf *btf_parse_module(const char *module_name, const void *data, u if (err) goto errout; + err = btf_check_type_tags(env, btf, btf_nr_types(base_btf)); + if (err) + goto errout; + btf_verifier_env_free(env); refcount_set(&btf->refcnt, 1); return btf; @@ -5429,7 +5708,8 @@ static 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) + const struct btf *need_btf, u32 need_type_id, + bool strict) { const struct btf_type *type; enum bpf_type_flag flag; @@ -5438,7 +5718,12 @@ bool btf_struct_ids_match(struct bpf_verifier_log *log, /* Are we already done? */ if (off == 0 && btf_types_are_same(btf, id, need_btf, need_type_id)) return true; - + /* In case of strict type match, we do not walk struct, the top level + * type match must succeed. When strict is true, off should have already + * been 0. + */ + if (strict) + return false; again: type = btf_type_by_id(btf, id); if (!type) @@ -5772,11 +6057,11 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, struct bpf_verifier_log *log = &env->log; u32 i, nargs, ref_id, ref_obj_id = 0; bool is_kfunc = btf_is_kernel(btf); + bool rel = false, kptr_get = false; const char *func_name, *ref_tname; const struct btf_type *t, *ref_t; const struct btf_param *args; int ref_regno = 0, ret; - bool rel = false; t = btf_type_by_id(btf, func_id); if (!t || !btf_type_is_func(t)) { @@ -5802,14 +6087,19 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, return -EINVAL; } - /* Only kfunc can be release func */ - if (is_kfunc) + if (is_kfunc) { + /* Only kfunc can be release func */ rel = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog), BTF_KFUNC_TYPE_RELEASE, func_id); + kptr_get = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog), + BTF_KFUNC_TYPE_KPTR_ACQUIRE, func_id); + } + /* check that BTF function arguments match actual types that the * verifier sees. */ for (i = 0; i < nargs; i++) { + enum bpf_arg_type arg_type = ARG_DONTCARE; u32 regno = i + 1; struct bpf_reg_state *reg = ®s[regno]; @@ -5830,12 +6120,58 @@ 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); - ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE, rel); + if (rel && reg->ref_obj_id) + arg_type |= OBJ_RELEASE; + ret = check_func_arg_reg_off(env, reg, regno, arg_type); if (ret < 0) return ret; - if (btf_get_prog_ctx_type(log, btf, t, - env->prog->type, i)) { + /* kptr_get is only true for kfunc */ + if (i == 0 && kptr_get) { + struct bpf_map_value_off_desc *off_desc; + + if (reg->type != PTR_TO_MAP_VALUE) { + bpf_log(log, "arg#0 expected pointer to map value\n"); + return -EINVAL; + } + + /* check_func_arg_reg_off allows var_off for + * PTR_TO_MAP_VALUE, but we need fixed offset to find + * off_desc. + */ + if (!tnum_is_const(reg->var_off)) { + bpf_log(log, "arg#0 must have constant offset\n"); + return -EINVAL; + } + + off_desc = bpf_map_kptr_off_contains(reg->map_ptr, reg->off + reg->var_off.value); + if (!off_desc || off_desc->type != BPF_KPTR_REF) { + bpf_log(log, "arg#0 no referenced kptr at map value offset=%llu\n", + reg->off + reg->var_off.value); + return -EINVAL; + } + + if (!btf_type_is_ptr(ref_t)) { + bpf_log(log, "arg#0 BTF type must be a double pointer\n"); + return -EINVAL; + } + + ref_t = btf_type_skip_modifiers(btf, ref_t->type, &ref_id); + ref_tname = btf_name_by_offset(btf, ref_t->name_off); + + if (!btf_type_is_struct(ref_t)) { + bpf_log(log, "kernel function %s args#%d pointer type %s %s is not supported\n", + func_name, i, btf_type_str(ref_t), ref_tname); + return -EINVAL; + } + if (!btf_struct_ids_match(log, btf, ref_id, 0, off_desc->kptr.btf, + off_desc->kptr.btf_id, true)) { + bpf_log(log, "kernel function %s args#%d expected pointer to %s %s\n", + func_name, i, btf_type_str(ref_t), ref_tname); + return -EINVAL; + } + /* rest of the arguments can be anything, like normal kfunc */ + } 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. */ @@ -5862,11 +6198,7 @@ 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; - /* Ensure only one argument is referenced - * PTR_TO_BTF_ID, check_func_arg_reg_off relies - * on only one referenced register being allowed - * for kfuncs. - */ + /* Ensure only one argument is referenced PTR_TO_BTF_ID */ if (reg->ref_obj_id) { if (ref_obj_id) { bpf_log(log, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", @@ -5886,7 +6218,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off); if (!btf_struct_ids_match(log, reg_btf, reg_ref_id, - reg->off, btf, ref_id)) { + reg->off, btf, ref_id, rel && reg->ref_obj_id)) { bpf_log(log, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n", func_name, i, btf_type_str(ref_t), ref_tname, @@ -6780,6 +7112,10 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type) return BTF_KFUNC_HOOK_TC; case BPF_PROG_TYPE_STRUCT_OPS: return BTF_KFUNC_HOOK_STRUCT_OPS; + case BPF_PROG_TYPE_TRACING: + return BTF_KFUNC_HOOK_TRACING; + case BPF_PROG_TYPE_SYSCALL: + return BTF_KFUNC_HOOK_SYSCALL; default: return BTF_KFUNC_HOOK_MAX; } @@ -6832,6 +7168,138 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, } EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set); +s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id) +{ + struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab; + struct btf_id_dtor_kfunc *dtor; + + if (!tab) + return -ENOENT; + /* Even though the size of tab->dtors[0] is > sizeof(u32), we only need + * to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func. + */ + BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0); + dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func); + if (!dtor) + return -ENOENT; + 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) +{ + struct btf_id_dtor_kfunc_tab *tab; + struct btf *btf; + u32 tab_cnt; + int ret; + + btf = btf_get_module_btf(owner); + if (!btf) { + if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { + pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n"); + return -ENOENT; + } + if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) { + pr_err("missing module BTF, cannot register dtor kfuncs\n"); + return -ENOENT; + } + return 0; + } + if (IS_ERR(btf)) + return PTR_ERR(btf); + + if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) { + pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT); + ret = -E2BIG; + 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))) { + ret = -EINVAL; + goto end; + } + + tab_cnt = tab ? tab->cnt : 0; + if (tab_cnt > U32_MAX - add_cnt) { + ret = -EOVERFLOW; + goto end; + } + if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) { + pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT); + ret = -E2BIG; + goto end; + } + + tab = krealloc(btf->dtor_kfunc_tab, + offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]), + GFP_KERNEL | __GFP_NOWARN); + if (!tab) { + ret = -ENOMEM; + goto end; + } + + if (!btf->dtor_kfunc_tab) + tab->cnt = 0; + btf->dtor_kfunc_tab = tab; + + memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0])); + tab->cnt += add_cnt; + + sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL); + + return 0; +end: + btf_free_dtor_kfunc_tab(btf); + btf_put(btf); + return ret; +} +EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs); + #define MAX_TYPES_ARE_COMPAT_DEPTH 2 static |