1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2019 Facebook */
5 #include <linux/bpf_verifier.h>
7 #include <linux/filter.h>
8 #include <linux/slab.h>
9 #include <linux/numa.h>
10 #include <linux/seq_file.h>
11 #include <linux/refcount.h>
12 #include <linux/mutex.h>
14 enum bpf_struct_ops_state {
15 BPF_STRUCT_OPS_STATE_INIT,
16 BPF_STRUCT_OPS_STATE_INUSE,
17 BPF_STRUCT_OPS_STATE_TOBEFREE,
20 #define BPF_STRUCT_OPS_COMMON_VALUE \
22 enum bpf_struct_ops_state state
24 struct bpf_struct_ops_value {
25 BPF_STRUCT_OPS_COMMON_VALUE;
26 char data[0] ____cacheline_aligned_in_smp;
29 struct bpf_struct_ops_map {
31 const struct bpf_struct_ops *st_ops;
32 /* protect map_update */
34 /* progs has all the bpf_prog that is populated
35 * to the func ptr of the kernel's struct
38 struct bpf_prog **progs;
39 /* image is a page that has all the trampolines
40 * that stores the func args before calling the bpf_prog.
41 * A PAGE_SIZE "image" is enough to store all trampoline for
45 /* uvalue->data stores the kernel struct
46 * (e.g. tcp_congestion_ops) that is more useful
47 * to userspace than the kvalue. For example,
48 * the bpf_prog's id is stored instead of the kernel
49 * address of a func ptr.
51 struct bpf_struct_ops_value *uvalue;
52 /* kvalue.data stores the actual kernel's struct
53 * (e.g. tcp_congestion_ops) that will be
54 * registered to the kernel subsystem.
56 struct bpf_struct_ops_value kvalue;
59 #define VALUE_PREFIX "bpf_struct_ops_"
60 #define VALUE_PREFIX_LEN (sizeof(VALUE_PREFIX) - 1)
62 /* bpf_struct_ops_##_name (e.g. bpf_struct_ops_tcp_congestion_ops) is
63 * the map's value exposed to the userspace and its btf-type-id is
64 * stored at the map->btf_vmlinux_value_type_id.
67 #define BPF_STRUCT_OPS_TYPE(_name) \
68 extern struct bpf_struct_ops bpf_##_name; \
70 struct bpf_struct_ops_##_name { \
71 BPF_STRUCT_OPS_COMMON_VALUE; \
72 struct _name data ____cacheline_aligned_in_smp; \
74 #include "bpf_struct_ops_types.h"
75 #undef BPF_STRUCT_OPS_TYPE
78 #define BPF_STRUCT_OPS_TYPE(_name) BPF_STRUCT_OPS_TYPE_##_name,
79 #include "bpf_struct_ops_types.h"
80 #undef BPF_STRUCT_OPS_TYPE
81 __NR_BPF_STRUCT_OPS_TYPE,
84 static struct bpf_struct_ops * const bpf_struct_ops[] = {
85 #define BPF_STRUCT_OPS_TYPE(_name) \
86 [BPF_STRUCT_OPS_TYPE_##_name] = &bpf_##_name,
87 #include "bpf_struct_ops_types.h"
88 #undef BPF_STRUCT_OPS_TYPE
91 const struct bpf_verifier_ops bpf_struct_ops_verifier_ops = {
94 const struct bpf_prog_ops bpf_struct_ops_prog_ops = {
97 static const struct btf_type *module_type;
99 void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
101 s32 type_id, value_id, module_id;
102 const struct btf_member *member;
103 struct bpf_struct_ops *st_ops;
104 const struct btf_type *t;
105 char value_name[128];
109 /* Ensure BTF type is emitted for "struct bpf_struct_ops_##_name" */
110 #define BPF_STRUCT_OPS_TYPE(_name) BTF_TYPE_EMIT(struct bpf_struct_ops_##_name);
111 #include "bpf_struct_ops_types.h"
112 #undef BPF_STRUCT_OPS_TYPE
114 module_id = btf_find_by_name_kind(btf, "module", BTF_KIND_STRUCT);
116 pr_warn("Cannot find struct module in btf_vmlinux\n");
119 module_type = btf_type_by_id(btf, module_id);
121 for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
122 st_ops = bpf_struct_ops[i];
124 if (strlen(st_ops->name) + VALUE_PREFIX_LEN >=
125 sizeof(value_name)) {
126 pr_warn("struct_ops name %s is too long\n",
130 sprintf(value_name, "%s%s", VALUE_PREFIX, st_ops->name);
132 value_id = btf_find_by_name_kind(btf, value_name,
135 pr_warn("Cannot find struct %s in btf_vmlinux\n",
140 type_id = btf_find_by_name_kind(btf, st_ops->name,
143 pr_warn("Cannot find struct %s in btf_vmlinux\n",
147 t = btf_type_by_id(btf, type_id);
148 if (btf_type_vlen(t) > BPF_STRUCT_OPS_MAX_NR_MEMBERS) {
149 pr_warn("Cannot support #%u members in struct %s\n",
150 btf_type_vlen(t), st_ops->name);
154 for_each_member(j, t, member) {
155 const struct btf_type *func_proto;
157 mname = btf_name_by_offset(btf, member->name_off);
159 pr_warn("anon member in struct %s is not supported\n",
164 if (btf_member_bitfield_size(t, member)) {
165 pr_warn("bit field member %s in struct %s is not supported\n",
166 mname, st_ops->name);
170 func_proto = btf_type_resolve_func_ptr(btf,
174 btf_distill_func_proto(log, btf,
176 &st_ops->func_models[j])) {
177 pr_warn("Error in parsing func ptr %s in struct %s\n",
178 mname, st_ops->name);
183 if (j == btf_type_vlen(t)) {
184 if (st_ops->init(btf)) {
185 pr_warn("Error in init bpf_struct_ops %s\n",
188 st_ops->type_id = type_id;
190 st_ops->value_id = value_id;
191 st_ops->value_type = btf_type_by_id(btf,
198 extern struct btf *btf_vmlinux;
200 static const struct bpf_struct_ops *
201 bpf_struct_ops_find_value(u32 value_id)
205 if (!value_id || !btf_vmlinux)
208 for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
209 if (bpf_struct_ops[i]->value_id == value_id)
210 return bpf_struct_ops[i];
216 const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id)
220 if (!type_id || !btf_vmlinux)
223 for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
224 if (bpf_struct_ops[i]->type_id == type_id)
225 return bpf_struct_ops[i];
231 static int bpf_struct_ops_map_get_next_key(struct bpf_map *map, void *key,
234 if (key && *(u32 *)key == 0)
237 *(u32 *)next_key = 0;
241 int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map, void *key,
244 struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;
245 struct bpf_struct_ops_value *uvalue, *kvalue;
246 enum bpf_struct_ops_state state;
248 if (unlikely(*(u32 *)key != 0))
251 kvalue = &st_map->kvalue;
252 /* Pair with smp_store_release() during map_update */
253 state = smp_load_acquire(&kvalue->state);
254 if (state == BPF_STRUCT_OPS_STATE_INIT) {
255 memset(value, 0, map->value_size);
259 /* No lock is needed. state and refcnt do not need
260 * to be updated together under atomic context.
262 uvalue = (struct bpf_struct_ops_value *)value;
263 memcpy(uvalue, st_map->uvalue, map->value_size);
264 uvalue->state = state;
265 refcount_set(&uvalue->refcnt, refcount_read(&kvalue->refcnt));
270 static void *bpf_struct_ops_map_lookup_elem(struct bpf_map *map, void *key)
272 return ERR_PTR(-EINVAL);
275 static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map)
277 const struct btf_type *t = st_map->st_ops->type;
280 for (i = 0; i < btf_type_vlen(t); i++) {
281 if (st_map->progs[i]) {
282 bpf_prog_put(st_map->progs[i]);
283 st_map->progs[i] = NULL;
288 static int check_zero_holes(const struct btf_type *t, void *data)
290 const struct btf_member *member;
291 u32 i, moff, msize, prev_mend = 0;
292 const struct btf_type *mtype;
294 for_each_member(i, t, member) {
295 moff = btf_member_bit_offset(t, member) / 8;
296 if (moff > prev_mend &&
297 memchr_inv(data + prev_mend, 0, moff - prev_mend))
300 mtype = btf_type_by_id(btf_vmlinux, member->type);
301 mtype = btf_resolve_size(btf_vmlinux, mtype, &msize,
304 return PTR_ERR(mtype);
305 prev_mend = moff + msize;
308 if (t->size > prev_mend &&
309 memchr_inv(data + prev_mend, 0, t->size - prev_mend))
315 static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
316 void *value, u64 flags)
318 struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;
319 const struct bpf_struct_ops *st_ops = st_map->st_ops;
320 struct bpf_struct_ops_value *uvalue, *kvalue;
321 const struct btf_member *member;
322 const struct btf_type *t = st_ops->type;
324 int prog_fd, err = 0;
331 if (*(u32 *)key != 0)
334 err = check_zero_holes(st_ops->value_type, value);
338 uvalue = (struct bpf_struct_ops_value *)value;
339 err = check_zero_holes(t, uvalue->data);
343 if (uvalue->state || refcount_read(&uvalue->refcnt))
346 uvalue = (struct bpf_struct_ops_value *)st_map->uvalue;
347 kvalue = (struct bpf_struct_ops_value *)&st_map->kvalue;
349 mutex_lock(&st_map->lock);
351 if (kvalue->state != BPF_STRUCT_OPS_STATE_INIT) {
356 memcpy(uvalue, value, map->value_size);
358 udata = &uvalue->data;
359 kdata = &kvalue->data;
360 image = st_map->image;
362 for_each_member(i, t, member) {
363 const struct btf_type *mtype, *ptype;
364 struct bpf_prog *prog;
367 moff = btf_member_bit_offset(t, member) / 8;
368 ptype = btf_type_resolve_ptr(btf_vmlinux, member->type, NULL);
369 if (ptype == module_type) {
370 if (*(void **)(udata + moff))
372 *(void **)(kdata + moff) = BPF_MODULE_OWNER;
376 err = st_ops->init_member(t, member, kdata, udata);
380 /* The ->init_member() has handled this member */
384 /* If st_ops->init_member does not handle it,
385 * we will only handle func ptrs and zero-ed members
386 * here. Reject everything else.
389 /* All non func ptr member must be 0 */
390 if (!ptype || !btf_type_is_func_proto(ptype)) {
393 mtype = btf_type_by_id(btf_vmlinux, member->type);
394 mtype = btf_resolve_size(btf_vmlinux, mtype, &msize,
397 err = PTR_ERR(mtype);
401 if (memchr_inv(udata + moff, 0, msize)) {
409 prog_fd = (int)(*(unsigned long *)(udata + moff));
410 /* Similar check as the attr->attach_prog_fd */
414 prog = bpf_prog_get(prog_fd);
419 st_map->progs[i] = prog;
421 if (prog->type != BPF_PROG_TYPE_STRUCT_OPS ||
422 prog->aux->attach_btf_id != st_ops->type_id ||
423 prog->expected_attach_type != i) {
428 err = arch_prepare_bpf_trampoline(image,
429 st_map->image + PAGE_SIZE,
430 &st_ops->func_models[i], 0,
431 &prog, 1, NULL, 0, NULL);
435 *(void **)(kdata + moff) = image;
438 /* put prog_id to udata */
439 *(unsigned long *)(udata + moff) = prog->aux->id;
442 refcount_set(&kvalue->refcnt, 1);
445 set_memory_ro((long)st_map->image, 1);
446 set_memory_x((long)st_map->image, 1);
447 err = st_ops->reg(kdata);
449 /* Pair with smp_load_acquire() during lookup_elem().
450 * It ensures the above udata updates (e.g. prog->aux->id)
451 * can be seen once BPF_STRUCT_OPS_STATE_INUSE is set.
453 smp_store_release(&kvalue->state, BPF_STRUCT_OPS_STATE_INUSE);
457 /* Error during st_ops->reg(). It is very unlikely since
458 * the above init_member() should have caught it earlier
459 * before reg(). The only possibility is if there was a race
460 * in registering the struct_ops (under the same name) to
461 * a sub-system through different struct_ops's maps.
463 set_memory_nx((long)st_map->image, 1);
464 set_memory_rw((long)st_map->image, 1);
468 bpf_struct_ops_map_put_progs(st_map);
469 memset(uvalue, 0, map->value_size);
470 memset(kvalue, 0, map->value_size);
472 mutex_unlock(&st_map->lock);
476 static int bpf_struct_ops_map_delete_elem(struct bpf_map *map, void *key)
478 enum bpf_struct_ops_state prev_state;
479 struct bpf_struct_ops_map *st_map;
481 st_map = (struct bpf_struct_ops_map *)map;
482 prev_state = cmpxchg(&st_map->kvalue.state,
483 BPF_STRUCT_OPS_STATE_INUSE,
484 BPF_STRUCT_OPS_STATE_TOBEFREE);
485 if (prev_state == BPF_STRUCT_OPS_STATE_INUSE) {
486 st_map->st_ops->unreg(&st_map->kvalue.data);
487 if (refcount_dec_and_test(&st_map->kvalue.refcnt))
494 static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key,
500 value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN);
504 err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);
506 btf_type_seq_show(btf_vmlinux, map->btf_vmlinux_value_type_id,
514 static void bpf_struct_ops_map_free(struct bpf_map *map)
516 struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;
519 bpf_struct_ops_map_put_progs(st_map);
520 bpf_map_area_free(st_map->progs);
521 bpf_jit_free_exec(st_map->image);
522 bpf_map_area_free(st_map->uvalue);
523 bpf_map_area_free(st_map);
526 static int bpf_struct_ops_map_alloc_check(union bpf_attr *attr)
528 if (attr->key_size != sizeof(unsigned int) || attr->max_entries != 1 ||
529 attr->map_flags || !attr->btf_vmlinux_value_type_id)
534 static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
536 const struct bpf_struct_ops *st_ops;
537 size_t map_total_size, st_map_size;
538 struct bpf_struct_ops_map *st_map;
539 const struct btf_type *t, *vt;
540 struct bpf_map_memory mem;
544 if (!capable(CAP_SYS_ADMIN))
545 return ERR_PTR(-EPERM);
547 st_ops = bpf_struct_ops_find_value(attr->btf_vmlinux_value_type_id);
549 return ERR_PTR(-ENOTSUPP);
551 vt = st_ops->value_type;
552 if (attr->value_size != vt->size)
553 return ERR_PTR(-EINVAL);
557 st_map_size = sizeof(*st_map) +
559 * struct bpf_struct_ops_tcp_congestions_ops
561 (vt->size - sizeof(struct bpf_struct_ops_value));
562 map_total_size = st_map_size +
565 /* struct bpf_progs **progs */
566 btf_type_vlen(t) * sizeof(struct bpf_prog *);
567 err = bpf_map_charge_init(&mem, map_total_size);
571 st_map = bpf_map_area_alloc(st_map_size, NUMA_NO_NODE);
573 bpf_map_charge_finish(&mem);
574 return ERR_PTR(-ENOMEM);
576 st_map->st_ops = st_ops;
579 st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE);
581 bpf_map_area_alloc(btf_type_vlen(t) * sizeof(struct bpf_prog *),
583 st_map->image = bpf_jit_alloc_exec(PAGE_SIZE);
584 if (!st_map->uvalue || !st_map->progs || !st_map->image) {
585 bpf_struct_ops_map_free(map);
586 bpf_map_charge_finish(&mem);
587 return ERR_PTR(-ENOMEM);
590 mutex_init(&st_map->lock);
591 set_vm_flush_reset_perms(st_map->image);
592 bpf_map_init_from_attr(map, attr);
593 bpf_map_charge_move(&map->memory, &mem);
598 const struct bpf_map_ops bpf_struct_ops_map_ops = {
599 .map_alloc_check = bpf_struct_ops_map_alloc_check,
600 .map_alloc = bpf_struct_ops_map_alloc,
601 .map_free = bpf_struct_ops_map_free,
602 .map_get_next_key = bpf_struct_ops_map_get_next_key,
603 .map_lookup_elem = bpf_struct_ops_map_lookup_elem,
604 .map_delete_elem = bpf_struct_ops_map_delete_elem,
605 .map_update_elem = bpf_struct_ops_map_update_elem,
606 .map_seq_show_elem = bpf_struct_ops_map_seq_show_elem,
609 /* "const void *" because some subsystem is
610 * passing a const (e.g. const struct tcp_congestion_ops *)
612 bool bpf_struct_ops_get(const void *kdata)
614 struct bpf_struct_ops_value *kvalue;
616 kvalue = container_of(kdata, struct bpf_struct_ops_value, data);
618 return refcount_inc_not_zero(&kvalue->refcnt);
621 void bpf_struct_ops_put(const void *kdata)
623 struct bpf_struct_ops_value *kvalue;
625 kvalue = container_of(kdata, struct bpf_struct_ops_value, data);
626 if (refcount_dec_and_test(&kvalue->refcnt)) {
627 struct bpf_struct_ops_map *st_map;
629 st_map = container_of(kvalue, struct bpf_struct_ops_map,
631 bpf_map_put(&st_map->map);