1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Functions to manage eBPF programs attached to cgroups
4 *
5 * Copyright (c) 2016 Daniel Mack
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/atomic.h>
10 #include <linux/cgroup.h>
11 #include <linux/filter.h>
12 #include <linux/slab.h>
13 #include <linux/sysctl.h>
14 #include <linux/string.h>
15 #include <linux/bpf.h>
16 #include <linux/bpf-cgroup.h>
17 #include <linux/bpf_lsm.h>
18 #include <linux/bpf_verifier.h>
19 #include <net/sock.h>
20 #include <net/bpf_sk_storage.h>
21
22 #include "../cgroup/cgroup-internal.h"
23
24 DEFINE_STATIC_KEY_ARRAY_FALSE(cgroup_bpf_enabled_key, MAX_CGROUP_BPF_ATTACH_TYPE);
25 EXPORT_SYMBOL(cgroup_bpf_enabled_key);
26
27 /*
28 * cgroup bpf destruction makes heavy use of work items and there can be a lot
29 * of concurrent destructions. Use a separate workqueue so that cgroup bpf
30 * destruction work items don't end up filling up max_active of system_wq
31 * which may lead to deadlock.
32 */
33 static struct workqueue_struct *cgroup_bpf_destroy_wq;
34
cgroup_bpf_wq_init(void)35 static int __init cgroup_bpf_wq_init(void)
36 {
37 cgroup_bpf_destroy_wq = alloc_workqueue("cgroup_bpf_destroy", 0, 1);
38 if (!cgroup_bpf_destroy_wq)
39 panic("Failed to alloc workqueue for cgroup bpf destroy.\n");
40 return 0;
41 }
42 core_initcall(cgroup_bpf_wq_init);
43
44 /* __always_inline is necessary to prevent indirect call through run_prog
45 * function pointer.
46 */
47 static __always_inline int
bpf_prog_run_array_cg(const struct cgroup_bpf * cgrp,enum cgroup_bpf_attach_type atype,const void * ctx,bpf_prog_run_fn run_prog,int retval,u32 * ret_flags)48 bpf_prog_run_array_cg(const struct cgroup_bpf *cgrp,
49 enum cgroup_bpf_attach_type atype,
50 const void *ctx, bpf_prog_run_fn run_prog,
51 int retval, u32 *ret_flags)
52 {
53 const struct bpf_prog_array_item *item;
54 const struct bpf_prog *prog;
55 const struct bpf_prog_array *array;
56 struct bpf_run_ctx *old_run_ctx;
57 struct bpf_cg_run_ctx run_ctx;
58 u32 func_ret;
59
60 run_ctx.retval = retval;
61 migrate_disable();
62 rcu_read_lock();
63 array = rcu_dereference(cgrp->effective[atype]);
64 item = &array->items[0];
65 old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
66 while ((prog = READ_ONCE(item->prog))) {
67 run_ctx.prog_item = item;
68 func_ret = run_prog(prog, ctx);
69 if (ret_flags) {
70 *(ret_flags) |= (func_ret >> 1);
71 func_ret &= 1;
72 }
73 if (!func_ret && !IS_ERR_VALUE((long)run_ctx.retval))
74 run_ctx.retval = -EPERM;
75 item++;
76 }
77 bpf_reset_run_ctx(old_run_ctx);
78 rcu_read_unlock();
79 migrate_enable();
80 return run_ctx.retval;
81 }
82
__cgroup_bpf_run_lsm_sock(const void * ctx,const struct bpf_insn * insn)83 unsigned int __cgroup_bpf_run_lsm_sock(const void *ctx,
84 const struct bpf_insn *insn)
85 {
86 const struct bpf_prog *shim_prog;
87 struct sock *sk;
88 struct cgroup *cgrp;
89 int ret = 0;
90 u64 *args;
91
92 args = (u64 *)ctx;
93 sk = (void *)(unsigned long)args[0];
94 /*shim_prog = container_of(insn, struct bpf_prog, insnsi);*/
95 shim_prog = (const struct bpf_prog *)((void *)insn - offsetof(struct bpf_prog, insnsi));
96
97 cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
98 if (likely(cgrp))
99 ret = bpf_prog_run_array_cg(&cgrp->bpf,
100 shim_prog->aux->cgroup_atype,
101 ctx, bpf_prog_run, 0, NULL);
102 return ret;
103 }
104
__cgroup_bpf_run_lsm_socket(const void * ctx,const struct bpf_insn * insn)105 unsigned int __cgroup_bpf_run_lsm_socket(const void *ctx,
106 const struct bpf_insn *insn)
107 {
108 const struct bpf_prog *shim_prog;
109 struct socket *sock;
110 struct cgroup *cgrp;
111 int ret = 0;
112 u64 *args;
113
114 args = (u64 *)ctx;
115 sock = (void *)(unsigned long)args[0];
116 /*shim_prog = container_of(insn, struct bpf_prog, insnsi);*/
117 shim_prog = (const struct bpf_prog *)((void *)insn - offsetof(struct bpf_prog, insnsi));
118
119 cgrp = sock_cgroup_ptr(&sock->sk->sk_cgrp_data);
120 if (likely(cgrp))
121 ret = bpf_prog_run_array_cg(&cgrp->bpf,
122 shim_prog->aux->cgroup_atype,
123 ctx, bpf_prog_run, 0, NULL);
124 return ret;
125 }
126
__cgroup_bpf_run_lsm_current(const void * ctx,const struct bpf_insn * insn)127 unsigned int __cgroup_bpf_run_lsm_current(const void *ctx,
128 const struct bpf_insn *insn)
129 {
130 const struct bpf_prog *shim_prog;
131 struct cgroup *cgrp;
132 int ret = 0;
133
134 /*shim_prog = container_of(insn, struct bpf_prog, insnsi);*/
135 shim_prog = (const struct bpf_prog *)((void *)insn - offsetof(struct bpf_prog, insnsi));
136
137 /* We rely on trampoline's __bpf_prog_enter_lsm_cgroup to grab RCU read lock. */
138 cgrp = task_dfl_cgroup(current);
139 if (likely(cgrp))
140 ret = bpf_prog_run_array_cg(&cgrp->bpf,
141 shim_prog->aux->cgroup_atype,
142 ctx, bpf_prog_run, 0, NULL);
143 return ret;
144 }
145
146 #ifdef CONFIG_BPF_LSM
147 struct cgroup_lsm_atype {
148 u32 attach_btf_id;
149 int refcnt;
150 };
151
152 static struct cgroup_lsm_atype cgroup_lsm_atype[CGROUP_LSM_NUM];
153
154 static enum cgroup_bpf_attach_type
bpf_cgroup_atype_find(enum bpf_attach_type attach_type,u32 attach_btf_id)155 bpf_cgroup_atype_find(enum bpf_attach_type attach_type, u32 attach_btf_id)
156 {
157 int i;
158
159 lockdep_assert_held(&cgroup_mutex);
160
161 if (attach_type != BPF_LSM_CGROUP)
162 return to_cgroup_bpf_attach_type(attach_type);
163
164 for (i = 0; i < ARRAY_SIZE(cgroup_lsm_atype); i++)
165 if (cgroup_lsm_atype[i].attach_btf_id == attach_btf_id)
166 return CGROUP_LSM_START + i;
167
168 for (i = 0; i < ARRAY_SIZE(cgroup_lsm_atype); i++)
169 if (cgroup_lsm_atype[i].attach_btf_id == 0)
170 return CGROUP_LSM_START + i;
171
172 return -E2BIG;
173
174 }
175
bpf_cgroup_atype_get(u32 attach_btf_id,int cgroup_atype)176 void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype)
177 {
178 int i = cgroup_atype - CGROUP_LSM_START;
179
180 lockdep_assert_held(&cgroup_mutex);
181
182 WARN_ON_ONCE(cgroup_lsm_atype[i].attach_btf_id &&
183 cgroup_lsm_atype[i].attach_btf_id != attach_btf_id);
184
185 cgroup_lsm_atype[i].attach_btf_id = attach_btf_id;
186 cgroup_lsm_atype[i].refcnt++;
187 }
188
bpf_cgroup_atype_put(int cgroup_atype)189 void bpf_cgroup_atype_put(int cgroup_atype)
190 {
191 int i = cgroup_atype - CGROUP_LSM_START;
192
193 cgroup_lock();
194 if (--cgroup_lsm_atype[i].refcnt <= 0)
195 cgroup_lsm_atype[i].attach_btf_id = 0;
196 WARN_ON_ONCE(cgroup_lsm_atype[i].refcnt < 0);
197 cgroup_unlock();
198 }
199 #else
200 static enum cgroup_bpf_attach_type
bpf_cgroup_atype_find(enum bpf_attach_type attach_type,u32 attach_btf_id)201 bpf_cgroup_atype_find(enum bpf_attach_type attach_type, u32 attach_btf_id)
202 {
203 if (attach_type != BPF_LSM_CGROUP)
204 return to_cgroup_bpf_attach_type(attach_type);
205 return -EOPNOTSUPP;
206 }
207 #endif /* CONFIG_BPF_LSM */
208
cgroup_bpf_offline(struct cgroup * cgrp)209 void cgroup_bpf_offline(struct cgroup *cgrp)
210 {
211 cgroup_get(cgrp);
212 percpu_ref_kill(&cgrp->bpf.refcnt);
213 }
214
bpf_cgroup_storages_free(struct bpf_cgroup_storage * storages[])215 static void bpf_cgroup_storages_free(struct bpf_cgroup_storage *storages[])
216 {
217 enum bpf_cgroup_storage_type stype;
218
219 for_each_cgroup_storage_type(stype)
220 bpf_cgroup_storage_free(storages[stype]);
221 }
222
bpf_cgroup_storages_alloc(struct bpf_cgroup_storage * storages[],struct bpf_cgroup_storage * new_storages[],enum bpf_attach_type type,struct bpf_prog * prog,struct cgroup * cgrp)223 static int bpf_cgroup_storages_alloc(struct bpf_cgroup_storage *storages[],
224 struct bpf_cgroup_storage *new_storages[],
225 enum bpf_attach_type type,
226 struct bpf_prog *prog,
227 struct cgroup *cgrp)
228 {
229 enum bpf_cgroup_storage_type stype;
230 struct bpf_cgroup_storage_key key;
231 struct bpf_map *map;
232
233 key.cgroup_inode_id = cgroup_id(cgrp);
234 key.attach_type = type;
235
236 for_each_cgroup_storage_type(stype) {
237 map = prog->aux->cgroup_storage[stype];
238 if (!map)
239 continue;
240
241 storages[stype] = cgroup_storage_lookup((void *)map, &key, false);
242 if (storages[stype])
243 continue;
244
245 storages[stype] = bpf_cgroup_storage_alloc(prog, stype);
246 if (IS_ERR(storages[stype])) {
247 bpf_cgroup_storages_free(new_storages);
248 return -ENOMEM;
249 }
250
251 new_storages[stype] = storages[stype];
252 }
253
254 return 0;
255 }
256
bpf_cgroup_storages_assign(struct bpf_cgroup_storage * dst[],struct bpf_cgroup_storage * src[])257 static void bpf_cgroup_storages_assign(struct bpf_cgroup_storage *dst[],
258 struct bpf_cgroup_storage *src[])
259 {
260 enum bpf_cgroup_storage_type stype;
261
262 for_each_cgroup_storage_type(stype)
263 dst[stype] = src[stype];
264 }
265
bpf_cgroup_storages_link(struct bpf_cgroup_storage * storages[],struct cgroup * cgrp,enum bpf_attach_type attach_type)266 static void bpf_cgroup_storages_link(struct bpf_cgroup_storage *storages[],
267 struct cgroup *cgrp,
268 enum bpf_attach_type attach_type)
269 {
270 enum bpf_cgroup_storage_type stype;
271
272 for_each_cgroup_storage_type(stype)
273 bpf_cgroup_storage_link(storages[stype], cgrp, attach_type);
274 }
275
276 /* Called when bpf_cgroup_link is auto-detached from dying cgroup.
277 * It drops cgroup and bpf_prog refcounts, and marks bpf_link as defunct. It
278 * doesn't free link memory, which will eventually be done by bpf_link's
279 * release() callback, when its last FD is closed.
280 */
bpf_cgroup_link_auto_detach(struct bpf_cgroup_link * link)281 static void bpf_cgroup_link_auto_detach(struct bpf_cgroup_link *link)
282 {
283 cgroup_put(link->cgroup);
284 link->cgroup = NULL;
285 }
286
287 /**
288 * cgroup_bpf_release() - put references of all bpf programs and
289 * release all cgroup bpf data
290 * @work: work structure embedded into the cgroup to modify
291 */
cgroup_bpf_release(struct work_struct * work)292 static void cgroup_bpf_release(struct work_struct *work)
293 {
294 struct cgroup *p, *cgrp = container_of(work, struct cgroup,
295 bpf.release_work);
296 struct bpf_prog_array *old_array;
297 struct list_head *storages = &cgrp->bpf.storages;
298 struct bpf_cgroup_storage *storage, *stmp;
299
300 unsigned int atype;
301
302 cgroup_lock();
303
304 for (atype = 0; atype < ARRAY_SIZE(cgrp->bpf.progs); atype++) {
305 struct hlist_head *progs = &cgrp->bpf.progs[atype];
306 struct bpf_prog_list *pl;
307 struct hlist_node *pltmp;
308
309 hlist_for_each_entry_safe(pl, pltmp, progs, node) {
310 hlist_del(&pl->node);
311 if (pl->prog) {
312 if (pl->prog->expected_attach_type == BPF_LSM_CGROUP)
313 bpf_trampoline_unlink_cgroup_shim(pl->prog);
314 bpf_prog_put(pl->prog);
315 }
316 if (pl->link) {
317 if (pl->link->link.prog->expected_attach_type == BPF_LSM_CGROUP)
318 bpf_trampoline_unlink_cgroup_shim(pl->link->link.prog);
319 bpf_cgroup_link_auto_detach(pl->link);
320 }
321 kfree(pl);
322 static_branch_dec(&cgroup_bpf_enabled_key[atype]);
323 }
324 old_array = rcu_dereference_protected(
325 cgrp->bpf.effective[atype],
326 lockdep_is_held(&cgroup_mutex));
327 bpf_prog_array_free(old_array);
328 }
329
330 list_for_each_entry_safe(storage, stmp, storages, list_cg) {
331 bpf_cgroup_storage_unlink(storage);
332 bpf_cgroup_storage_free(storage);
333 }
334
335 cgroup_unlock();
336
337 for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
338 cgroup_bpf_put(p);
339
340 percpu_ref_exit(&cgrp->bpf.refcnt);
341 cgroup_put(cgrp);
342 }
343
344 /**
345 * cgroup_bpf_release_fn() - callback used to schedule releasing
346 * of bpf cgroup data
347 * @ref: percpu ref counter structure
348 */
cgroup_bpf_release_fn(struct percpu_ref * ref)349 static void cgroup_bpf_release_fn(struct percpu_ref *ref)
350 {
351 struct cgroup *cgrp = container_of(ref, struct cgroup, bpf.refcnt);
352
353 INIT_WORK(&cgrp->bpf.release_work, cgroup_bpf_release);
354 queue_work(cgroup_bpf_destroy_wq, &cgrp->bpf.release_work);
355 }
356
357 /* Get underlying bpf_prog of bpf_prog_list entry, regardless if it's through
358 * link or direct prog.
359 */
prog_list_prog(struct bpf_prog_list * pl)360 static struct bpf_prog *prog_list_prog(struct bpf_prog_list *pl)
361 {
362 if (pl->prog)
363 return pl->prog;
364 if (pl->link)
365 return pl->link->link.prog;
366 return NULL;
367 }
368
369 /* count number of elements in the list.
370 * it's slow but the list cannot be long
371 */
prog_list_length(struct hlist_head * head,int * preorder_cnt)372 static u32 prog_list_length(struct hlist_head *head, int *preorder_cnt)
373 {
374 struct bpf_prog_list *pl;
375 u32 cnt = 0;
376
377 hlist_for_each_entry(pl, head, node) {
378 if (!prog_list_prog(pl))
379 continue;
380 if (preorder_cnt && (pl->flags & BPF_F_PREORDER))
381 (*preorder_cnt)++;
382 cnt++;
383 }
384 return cnt;
385 }
386
387 /* if parent has non-overridable prog attached,
388 * disallow attaching new programs to the descendent cgroup.
389 * if parent has overridable or multi-prog, allow attaching
390 */
hierarchy_allows_attach(struct cgroup * cgrp,enum cgroup_bpf_attach_type atype)391 static bool hierarchy_allows_attach(struct cgroup *cgrp,
392 enum cgroup_bpf_attach_type atype)
393 {
394 struct cgroup *p;
395
396 p = cgroup_parent(cgrp);
397 if (!p)
398 return true;
399 do {
400 u32 flags = p->bpf.flags[atype];
401 u32 cnt;
402
403 if (flags & BPF_F_ALLOW_MULTI)
404 return true;
405 cnt = prog_list_length(&p->bpf.progs[atype], NULL);
406 WARN_ON_ONCE(cnt > 1);
407 if (cnt == 1)
408 return !!(flags & BPF_F_ALLOW_OVERRIDE);
409 p = cgroup_parent(p);
410 } while (p);
411 return true;
412 }
413
414 /* compute a chain of effective programs for a given cgroup:
415 * start from the list of programs in this cgroup and add
416 * all parent programs.
417 * Note that parent's F_ALLOW_OVERRIDE-type program is yielding
418 * to programs in this cgroup
419 */
compute_effective_progs(struct cgroup * cgrp,enum cgroup_bpf_attach_type atype,struct bpf_prog_array ** array)420 static int compute_effective_progs(struct cgroup *cgrp,
421 enum cgroup_bpf_attach_type atype,
422 struct bpf_prog_array **array)
423 {
424 struct bpf_prog_array_item *item;
425 struct bpf_prog_array *progs;
426 struct bpf_prog_list *pl;
427 struct cgroup *p = cgrp;
428 int i, j, cnt = 0, preorder_cnt = 0, fstart, bstart, init_bstart;
429
430 /* count number of effective programs by walking parents */
431 do {
432 if (cnt == 0 || (p->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
433 cnt += prog_list_length(&p->bpf.progs[atype], &preorder_cnt);
434 p = cgroup_parent(p);
435 } while (p);
436
437 progs = bpf_prog_array_alloc(cnt, GFP_KERNEL);
438 if (!progs)
439 return -ENOMEM;
440
441 /* populate the array with effective progs */
442 cnt = 0;
443 p = cgrp;
444 fstart = preorder_cnt;
445 bstart = preorder_cnt - 1;
446 do {
447 if (cnt > 0 && !(p->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
448 continue;
449
450 init_bstart = bstart;
451 hlist_for_each_entry(pl, &p->bpf.progs[atype], node) {
452 if (!prog_list_prog(pl))
453 continue;
454
455 if (pl->flags & BPF_F_PREORDER) {
456 item = &progs->items[bstart];
457 bstart--;
458 } else {
459 item = &progs->items[fstart];
460 fstart++;
461 }
462 item->prog = prog_list_prog(pl);
463 bpf_cgroup_storages_assign(item->cgroup_storage,
464 pl->storage);
465 cnt++;
466 }
467
468 /* reverse pre-ordering progs at this cgroup level */
469 for (i = bstart + 1, j = init_bstart; i < j; i++, j--)
470 swap(progs->items[i], progs->items[j]);
471
472 } while ((p = cgroup_parent(p)));
473
474 *array = progs;
475 return 0;
476 }
477
activate_effective_progs(struct cgroup * cgrp,enum cgroup_bpf_attach_type atype,struct bpf_prog_array * old_array)478 static void activate_effective_progs(struct cgroup *cgrp,
479 enum cgroup_bpf_attach_type atype,
480 struct bpf_prog_array *old_array)
481 {
482 old_array = rcu_replace_pointer(cgrp->bpf.effective[atype], old_array,
483 lockdep_is_held(&cgroup_mutex));
484 /* free prog array after grace period, since __cgroup_bpf_run_*()
485 * might be still walking the array
486 */
487 bpf_prog_array_free(old_array);
488 }
489
490 /**
491 * cgroup_bpf_inherit() - inherit effective programs from parent
492 * @cgrp: the cgroup to modify
493 */
cgroup_bpf_inherit(struct cgroup * cgrp)494 int cgroup_bpf_inherit(struct cgroup *cgrp)
495 {
496 /* has to use marco instead of const int, since compiler thinks
497 * that array below is variable length
498 */
499 #define NR ARRAY_SIZE(cgrp->bpf.effective)
500 struct bpf_prog_array *arrays[NR] = {};
501 struct cgroup *p;
502 int ret, i;
503
504 ret = percpu_ref_init(&cgrp->bpf.refcnt, cgroup_bpf_release_fn, 0,
505 GFP_KERNEL);
506 if (ret)
507 return ret;
508
509 for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
510 cgroup_bpf_get(p);
511
512 for (i = 0; i < NR; i++)
513 INIT_HLIST_HEAD(&cgrp->bpf.progs[i]);
514
515 INIT_LIST_HEAD(&cgrp->bpf.storages);
516
517 for (i = 0; i < NR; i++)
518 if (compute_effective_progs(cgrp, i, &arrays[i]))
519 goto cleanup;
520
521 for (i = 0; i < NR; i++)
522 activate_effective_progs(cgrp, i, arrays[i]);
523
524 return 0;
525 cleanup:
526 for (i = 0; i < NR; i++)
527 bpf_prog_array_free(arrays[i]);
528
529 for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
530 cgroup_bpf_put(p);
531
532 percpu_ref_exit(&cgrp->bpf.refcnt);
533
534 return -ENOMEM;
535 }
536
update_effective_progs(struct cgroup * cgrp,enum cgroup_bpf_attach_type atype)537 static int update_effective_progs(struct cgroup *cgrp,
538 enum cgroup_bpf_attach_type atype)
539 {
540 struct cgroup_subsys_state *css;
541 int err;
542
543 /* allocate and recompute effective prog arrays */
544 css_for_each_descendant_pre(css, &cgrp->self) {
545 struct cgroup *desc = container_of(css, struct cgroup, self);
546
547 if (percpu_ref_is_zero(&desc->bpf.refcnt))
548 continue;
549
550 err = compute_effective_progs(desc, atype, &desc->bpf.inactive);
551 if (err)
552 goto cleanup;
553 }
554
555 /* all allocations were successful. Activate all prog arrays */
556 css_for_each_descendant_pre(css, &cgrp->self) {
557 struct cgroup *desc = container_of(css, struct cgroup, self);
558
559 if (percpu_ref_is_zero(&desc->bpf.refcnt)) {
560 if (unlikely(desc->bpf.inactive)) {
561 bpf_prog_array_free(desc->bpf.inactive);
562 desc->bpf.inactive = NULL;
563 }
564 continue;
565 }
566
567 activate_effective_progs(desc, atype, desc->bpf.inactive);
568 desc->bpf.inactive = NULL;
569 }
570
571 return 0;
572
573 cleanup:
574 /* oom while computing effective. Free all computed effective arrays
575 * since they were not activated
576 */
577 css_for_each_descendant_pre(css, &cgrp->self) {
578 struct cgroup *desc = container_of(css, struct cgroup, self);
579
580 bpf_prog_array_free(desc->bpf.inactive);
581 desc->bpf.inactive = NULL;
582 }
583
584 return err;
585 }
586
587 #define BPF_CGROUP_MAX_PROGS 64
588
find_attach_entry(struct hlist_head * progs,struct bpf_prog * prog,struct bpf_cgroup_link * link,struct bpf_prog * replace_prog,bool allow_multi)589 static struct bpf_prog_list *find_attach_entry(struct hlist_head *progs,
590 struct bpf_prog *prog,
591 struct bpf_cgroup_link *link,
592 struct bpf_prog *replace_prog,
593 bool allow_multi)
594 {
595 struct bpf_prog_list *pl;
596
597 /* single-attach case */
598 if (!allow_multi) {
599 if (hlist_empty(progs))
600 return NULL;
601 return hlist_entry(progs->first, typeof(*pl), node);
602 }
603
604 hlist_for_each_entry(pl, progs, node) {
605 if (prog && pl->prog == prog && prog != replace_prog)
606 /* disallow attaching the same prog twice */
607 return ERR_PTR(-EINVAL);
608 if (link && pl->link == link)
609 /* disallow attaching the same link twice */
610 return ERR_PTR(-EINVAL);
611 }
612
613 /* direct prog multi-attach w/ replacement case */
614 if (replace_prog) {
615 hlist_for_each_entry(pl, progs, node) {
616 if (pl->prog == replace_prog)
617 /* a match found */
618 return pl;
619 }
620 /* prog to replace not found for cgroup */
621 return ERR_PTR(-ENOENT);
622 }
623
624 return NULL;
625 }
626
627 /**
628 * __cgroup_bpf_attach() - Attach the program or the link to a cgroup, and
629 * propagate the change to descendants
630 * @cgrp: The cgroup which descendants to traverse
631 * @prog: A program to attach
632 * @link: A link to attach
633 * @replace_prog: Previously attached program to replace if BPF_F_REPLACE is set
634 * @type: Type of attach operation
635 * @flags: Option flags
636 *
637 * Exactly one of @prog or @link can be non-null.
638 * Must be called with cgroup_mutex held.
639 */
__cgroup_bpf_attach(struct cgroup * cgrp,struct bpf_prog * prog,struct bpf_prog * replace_prog,struct bpf_cgroup_link * link,enum bpf_attach_type type,u32 flags)640 static int __cgroup_bpf_attach(struct cgroup *cgrp,
641 struct bpf_prog *prog, struct bpf_prog *replace_prog,
642 struct bpf_cgroup_link *link,
643 enum bpf_attach_type type, u32 flags)
644 {
645 u32 saved_flags = (flags & (BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI));
646 struct bpf_prog *old_prog = NULL;
647 struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
648 struct bpf_cgroup_storage *new_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
649 struct bpf_prog *new_prog = prog ? : link->link.prog;
650 enum cgroup_bpf_attach_type atype;
651 struct bpf_prog_list *pl;
652 struct hlist_head *progs;
653 int err;
654
655 if (((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI)) ||
656 ((flags & BPF_F_REPLACE) && !(flags & BPF_F_ALLOW_MULTI)))
657 /* invalid combination */
658 return -EINVAL;
659 if (link && (prog || replace_prog))
660 /* only either link or prog/replace_prog can be specified */
661 return -EINVAL;
662 if (!!replace_prog != !!(flags & BPF_F_REPLACE))
663 /* replace_prog implies BPF_F_REPLACE, and vice versa */
664 return -EINVAL;
665
666 atype = bpf_cgroup_atype_find(type, new_prog->aux->attach_btf_id);
667 if (atype < 0)
668 return -EINVAL;
669
670 progs = &cgrp->bpf.progs[atype];
671
672 if (!hierarchy_allows_attach(cgrp, atype))
673 return -EPERM;
674
675 if (!hlist_empty(progs) && cgrp->bpf.flags[atype] != saved_flags)
676 /* Disallow attaching non-overridable on top
677 * of existing overridable in this cgroup.
678 * Disallow attaching multi-prog if overridable or none
679 */
680 return -EPERM;
681
682 if (prog_list_length(progs, NULL) >= BPF_CGROUP_MAX_PROGS)
683 return -E2BIG;
684
685 pl = find_attach_entry(progs, prog, link, replace_prog,
686 flags & BPF_F_ALLOW_MULTI);
687 if (IS_ERR(pl))
688 return PTR_ERR(pl);
689
690 if (bpf_cgroup_storages_alloc(storage, new_storage, type,
691 prog ? : link->link.prog, cgrp))
692 return -ENOMEM;
693
694 if (pl) {
695 old_prog = pl->prog;
696 } else {
697 struct hlist_node *last = NULL;
698
699 pl = kmalloc(sizeof(*pl), GFP_KERNEL);
700 if (!pl) {
701 bpf_cgroup_storages_free(new_storage);
702 return -ENOMEM;
703 }
704 if (hlist_empty(progs))
705 hlist_add_head(&pl->node, progs);
706 else
707 hlist_for_each(last, progs) {
708 if (last->next)
709 continue;
710 hlist_add_behind(&pl->node, last);
711 break;
712 }
713 }
714
715 pl->prog = prog;
716 pl->link = link;
717 pl->flags = flags;
718 bpf_cgroup_storages_assign(pl->storage, storage);
719 cgrp->bpf.flags[atype] = saved_flags;
720
721 if (type == BPF_LSM_CGROUP) {
722 err = bpf_trampoline_link_cgroup_shim(new_prog, atype);
723 if (err)
724 goto cleanup;
725 }
726
727 err = update_effective_progs(cgrp, atype);
728 if (err)
729 goto cleanup_trampoline;
730
731 if (old_prog) {
732 if (type == BPF_LSM_CGROUP)
733 bpf_trampoline_unlink_cgroup_shim(old_prog);
734 bpf_prog_put(old_prog);
735 } else {
736 static_branch_inc(&cgroup_bpf_enabled_key[atype]);
737 }
738 bpf_cgroup_storages_link(new_storage, cgrp, type);
739 return 0;
740
741 cleanup_trampoline:
742 if (type == BPF_LSM_CGROUP)
743 bpf_trampoline_unlink_cgroup_shim(new_prog);
744
745 cleanup:
746 if (old_prog) {
747 pl->prog = old_prog;
748 pl->link = NULL;
749 }
750 bpf_cgroup_storages_free(new_storage);
751 if (!old_prog) {
752 hlist_del(&pl->node);
753 kfree(pl);
754 }
755 return err;
756 }
757
cgroup_bpf_attach(struct cgroup * cgrp,struct bpf_prog * prog,struct bpf_prog * replace_prog,struct bpf_cgroup_link * link,enum bpf_attach_type type,u32 flags)758 static int cgroup_bpf_attach(struct cgroup *cgrp,
759 struct bpf_prog *prog, struct bpf_prog *replace_prog,
760 struct bpf_cgroup_link *link,
761 enum bpf_attach_type type,
762 u32 flags)
763 {
764 int ret;
765
766 cgroup_lock();
767 ret = __cgroup_bpf_attach(cgrp, prog, replace_prog, link, type, flags);
768 cgroup_unlock();
769 return ret;
770 }
771
772 /* Swap updated BPF program for given link in effective program arrays across
773 * all descendant cgroups. This function is guaranteed to succeed.
774 */
replace_effective_prog(struct cgroup * cgrp,enum cgroup_bpf_attach_type atype,struct bpf_cgroup_link * link)775 static void replace_effective_prog(struct cgroup *cgrp,
776 enum cgroup_bpf_attach_type atype,
777 struct bpf_cgroup_link *link)
778 {
779 struct bpf_prog_array_item *item;
780 struct cgroup_subsys_state *css;
781 struct bpf_prog_array *progs;
782 struct bpf_prog_list *pl;
783 struct hlist_head *head;
784 struct cgroup *cg;
785 int pos;
786
787 css_for_each_descendant_pre(css, &cgrp->self) {
788 struct cgroup *desc = container_of(css, struct cgroup, self);
789
790 if (percpu_ref_is_zero(&desc->bpf.refcnt))
791 continue;
792
793 /* find position of link in effective progs array */
794 for (pos = 0, cg = desc; cg; cg = cgroup_parent(cg)) {
795 if (pos && !(cg->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
796 continue;
797
798 head = &cg->bpf.progs[atype];
799 hlist_for_each_entry(pl, head, node) {
800 if (!prog_list_prog(pl))
801 continue;
802 if (pl->link == link)
803 goto found;
804 pos++;
805 }
806 }
807 found:
808 BUG_ON(!cg);
809 progs = rcu_dereference_protected(
810 desc->bpf.effective[atype],
811 lockdep_is_held(&cgroup_mutex));
812 item = &progs->items[pos];
813 WRITE_ONCE(item->prog, link->link.prog);
814 }
815 }
816
817 /**
818 * __cgroup_bpf_replace() - Replace link's program and propagate the change
819 * to descendants
820 * @cgrp: The cgroup which descendants to traverse
821 * @link: A link for which to replace BPF program
822 * @new_prog: &struct bpf_prog for the target BPF program with its refcnt
823 * incremented
824 *
825 * Must be called with cgroup_mutex held.
826 */
__cgroup_bpf_replace(struct cgroup * cgrp,struct bpf_cgroup_link * link,struct bpf_prog * new_prog)827 static int __cgroup_bpf_replace(struct cgroup *cgrp,
828 struct bpf_cgroup_link *link,
829 struct bpf_prog *new_prog)
830 {
831 enum cgroup_bpf_attach_type atype;
832 struct bpf_prog *old_prog;
833 struct bpf_prog_list *pl;
834 struct hlist_head *progs;
835 bool found = false;
836
837 atype = bpf_cgroup_atype_find(link->type, new_prog->aux->attach_btf_id);
838 if (atype < 0)
839 return -EINVAL;
840
841 progs = &cgrp->bpf.progs[atype];
842
843 if (link->link.prog->type != new_prog->type)
844 return -EINVAL;
845
846 hlist_for_each_entry(pl, progs, node) {
847 if (pl->link == link) {
848 found = true;
849 break;
850 }
851 }
852 if (!found)
853 return -ENOENT;
854
855 old_prog = xchg(&link->link.prog, new_prog);
856 replace_effective_prog(cgrp, atype, link);
857 bpf_prog_put(old_prog);
858 return 0;
859 }
860
cgroup_bpf_replace(struct bpf_link * link,struct bpf_prog * new_prog,struct bpf_prog * old_prog)861 static int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *new_prog,
862 struct bpf_prog *old_prog)
863 {
864 struct bpf_cgroup_link *cg_link;
865 int ret;
866
867 cg_link = container_of(link, struct bpf_cgroup_link, link);
868
869 cgroup_lock();
870 /* link might have been auto-released by dying cgroup, so fail */
871 if (!cg_link->cgroup) {
872 ret = -ENOLINK;
873 goto out_unlock;
874 }
875 if (old_prog && link->prog != old_prog) {
876 ret = -EPERM;
877 goto out_unlock;
878 }
879 ret = __cgroup_bpf_replace(cg_link->cgroup, cg_link, new_prog);
880 out_unlock:
881 cgroup_unlock();
882 return ret;
883 }
884
find_detach_entry(struct hlist_head * progs,struct bpf_prog * prog,struct bpf_cgroup_link * link,bool allow_multi)885 static struct bpf_prog_list *find_detach_entry(struct hlist_head *progs,
886 struct bpf_prog *prog,
887 struct bpf_cgroup_link *link,
888 bool allow_multi)
889 {
890 struct bpf_prog_list *pl;
891
892 if (!allow_multi) {
893 if (hlist_empty(progs))
894 /* report error when trying to detach and nothing is attached */
895 return ERR_PTR(-ENOENT);
896
897 /* to maintain backward compatibility NONE and OVERRIDE cgroups
898 * allow detaching with invalid FD (prog==NULL) in legacy mode
899 */
900 return hlist_entry(progs->first, typeof(*pl), node);
901 }
902
903 if (!prog && !link)
904 /* to detach MULTI prog the user has to specify valid FD
905 * of the program or link to be detached
906 */
907 return ERR_PTR(-EINVAL);
908
909 /* find the prog or link and detach it */
910 hlist_for_each_entry(pl, progs, node) {
911 if (pl->prog == prog && pl->link == link)
912 return pl;
913 }
914 return ERR_PTR(-ENOENT);
915 }
916
917 /**
918 * purge_effective_progs() - After compute_effective_progs fails to alloc new
919 * cgrp->bpf.inactive table we can recover by
920 * recomputing the array in place.
921 *
922 * @cgrp: The cgroup which descendants to travers
923 * @prog: A program to detach or NULL
924 * @link: A link to detach or NULL
925 * @atype: Type of detach operation
926 */
purge_effective_progs(struct cgroup * cgrp,struct bpf_prog * prog,struct bpf_cgroup_link * link,enum cgroup_bpf_attach_type atype)927 static void purge_effective_progs(struct cgroup *cgrp, struct bpf_prog *prog,
928 struct bpf_cgroup_link *link,
929 enum cgroup_bpf_attach_type atype)
930 {
931 struct cgroup_subsys_state *css;
932 struct bpf_prog_array *progs;
933 struct bpf_prog_list *pl;
934 struct hlist_head *head;
935 struct cgroup *cg;
936 int pos;
937
938 /* recompute effective prog array in place */
939 css_for_each_descendant_pre(css, &cgrp->self) {
940 struct cgroup *desc = container_of(css, struct cgroup, self);
941
942 if (percpu_ref_is_zero(&desc->bpf.refcnt))
943 continue;
944
945 /* find position of link or prog in effective progs array */
946 for (pos = 0, cg = desc; cg; cg = cgroup_parent(cg)) {
947 if (pos && !(cg->bpf.flags[atype] & BPF_F_ALLOW_MULTI))
948 continue;
949
950 head = &cg->bpf.progs[atype];
951 hlist_for_each_entry(pl, head, node) {
952 if (!prog_list_prog(pl))
953 continue;
954 if (pl->prog == prog && pl->link == link)
955 goto found;
956 pos++;
957 }
958 }
959
960 /* no link or prog match, skip the cgroup of this layer */
961 continue;
962 found:
963 progs = rcu_dereference_protected(
964 desc->bpf.effective[atype],
965 lockdep_is_held(&cgroup_mutex));
966
967 /* Remove the program from the array */
968 WARN_ONCE(bpf_prog_array_delete_safe_at(progs, pos),
969 "Failed to purge a prog from array at index %d", pos);
970 }
971 }
972
973 /**
974 * __cgroup_bpf_detach() - Detach the program or link from a cgroup, and
975 * propagate the change to descendants
976 * @cgrp: The cgroup which descendants to traverse
977 * @prog: A program to detach or NULL
978 * @link: A link to detach or NULL
979 * @type: Type of detach operation
980 *
981 * At most one of @prog or @link can be non-NULL.
982 * Must be called with cgroup_mutex held.
983 */
__cgroup_bpf_detach(struct cgroup * cgrp,struct bpf_prog * prog,struct bpf_cgroup_link * link,enum bpf_attach_type type)984 static int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
985 struct bpf_cgroup_link *link, enum bpf_attach_type type)
986 {
987 enum cgroup_bpf_attach_type atype;
988 struct bpf_prog *old_prog;
989 struct bpf_prog_list *pl;
990 struct hlist_head *progs;
991 u32 attach_btf_id = 0;
992 u32 flags;
993
994 if (prog)
995 attach_btf_id = prog->aux->attach_btf_id;
996 if (link)
997 attach_btf_id = link->link.prog->aux->attach_btf_id;
998
999 atype = bpf_cgroup_atype_find(type, attach_btf_id);
1000 if (atype < 0)
1001 return -EINVAL;
1002
1003 progs = &cgrp->bpf.progs[atype];
1004 flags = cgrp->bpf.flags[atype];
1005
1006 if (prog && link)
1007 /* only one of prog or link can be specified */
1008 return -EINVAL;
1009
1010 pl = find_detach_entry(progs, prog, link, flags & BPF_F_ALLOW_MULTI);
1011 if (IS_ERR(pl))
1012 return PTR_ERR(pl);
1013
1014 /* mark it deleted, so it's ignored while recomputing effective */
1015 old_prog = pl->prog;
1016 pl->prog = NULL;
1017 pl->link = NULL;
1018
1019 if (update_effective_progs(cgrp, atype)) {
1020 /* if update effective array failed replace the prog with a dummy prog*/
1021 pl->prog = old_prog;
1022 pl->link = link;
1023 purge_effective_progs(cgrp, old_prog, link, atype);
1024 }
1025
1026 /* now can actually delete it from this cgroup list */
1027 hlist_del(&pl->node);
1028
1029 kfree(pl);
1030 if (hlist_empty(progs))
1031 /* last program was detached, reset flags to zero */
1032 cgrp->bpf.flags[atype] = 0;
1033 if (old_prog) {
1034 if (type == BPF_LSM_CGROUP)
1035 bpf_trampoline_unlink_cgroup_shim(old_prog);
1036 bpf_prog_put(old_prog);
1037 }
1038 static_branch_dec(&cgroup_bpf_enabled_key[atype]);
1039 return 0;
1040 }
1041
cgroup_bpf_detach(struct cgroup * cgrp,struct bpf_prog * prog,enum bpf_attach_type type)1042 static int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
1043 enum bpf_attach_type type)
1044 {
1045 int ret;
1046
1047 cgroup_lock();
1048 ret = __cgroup_bpf_detach(cgrp, prog, NULL, type);
1049 cgroup_unlock();
1050 return ret;
1051 }
1052
1053 /* Must be called with cgroup_mutex held to avoid races. */
__cgroup_bpf_query(struct cgroup * cgrp,const union bpf_attr * attr,union bpf_attr __user * uattr)1054 static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
1055 union bpf_attr __user *uattr)
1056 {
1057 __u32 __user *prog_attach_flags = u64_to_user_ptr(attr->query.prog_attach_flags);
1058 bool effective_query = attr->query.query_flags & BPF_F_QUERY_EFFECTIVE;
1059 __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
1060 enum bpf_attach_type type = attr->query.attach_type;
1061 enum cgroup_bpf_attach_type from_atype, to_atype;
1062 enum cgroup_bpf_attach_type atype;
1063 struct bpf_prog_array *effective;
1064 int cnt, ret = 0, i;
1065 int total_cnt = 0;
1066 u32 flags;
1067
1068 if (effective_query && prog_attach_flags)
1069 return -EINVAL;
1070
1071 if (type == BPF_LSM_CGROUP) {
1072 if (!effective_query && attr->query.prog_cnt &&
1073 prog_ids && !prog_attach_flags)
1074 return -EINVAL;
1075
1076 from_atype = CGROUP_LSM_START;
1077 to_atype = CGROUP_LSM_END;
1078 flags = 0;
1079 } else {
1080 from_atype = to_cgroup_bpf_attach_type(type);
1081 if (from_atype < 0)
1082 return -EINVAL;
1083 to_atype = from_atype;
1084 flags = cgrp->bpf.flags[from_atype];
1085 }
1086
1087 for (atype = from_atype; atype <= to_atype; atype++) {
1088 if (effective_query) {
1089 effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
1090 lockdep_is_held(&cgroup_mutex));
1091 total_cnt += bpf_prog_array_length(effective);
1092 } else {
1093 total_cnt += prog_list_length(&cgrp->bpf.progs[atype], NULL);
1094 }
1095 }
1096
1097 /* always output uattr->query.attach_flags as 0 during effective query */
1098 flags = effective_query ? 0 : flags;
1099 if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
1100 return -EFAULT;
1101 if (copy_to_user(&uattr->query.prog_cnt, &total_cnt, sizeof(total_cnt)))
1102 return -EFAULT;
1103 if (attr->query.prog_cnt == 0 || !prog_ids || !total_cnt)
1104 /* return early if user requested only program count + flags */
1105 return 0;
1106
1107 if (attr->query.prog_cnt < total_cnt) {
1108 total_cnt = attr->query.prog_cnt;
1109 ret = -ENOSPC;
1110 }
1111
1112 for (atype = from_atype; atype <= to_atype && total_cnt; atype++) {
1113 if (effective_query) {
1114 effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
1115 lockdep_is_held(&cgroup_mutex));
1116 cnt = min_t(int, bpf_prog_array_length(effective), total_cnt);
1117 ret = bpf_prog_array_copy_to_user(effective, prog_ids, cnt);
1118 } else {
1119 struct hlist_head *progs;
1120 struct bpf_prog_list *pl;
1121 struct bpf_prog *prog;
1122 u32 id;
1123
1124 progs = &cgrp->bpf.progs[atype];
1125 cnt = min_t(int, prog_list_length(progs, NULL), total_cnt);
1126 i = 0;
1127 hlist_for_each_entry(pl, progs, node) {
1128 prog = prog_list_prog(pl);
1129 id = prog->aux->id;
1130 if (copy_to_user(prog_ids + i, &id, sizeof(id)))
1131 return -EFAULT;
1132 if (++i == cnt)
1133 break;
1134 }
1135
1136 if (prog_attach_flags) {
1137 flags = cgrp->bpf.flags[atype];
1138
1139 for (i = 0; i < cnt; i++)
1140 if (copy_to_user(prog_attach_flags + i,
1141 &flags, sizeof(flags)))
1142 return -EFAULT;
1143 prog_attach_flags += cnt;
1144 }
1145 }
1146
1147 prog_ids += cnt;
1148 total_cnt -= cnt;
1149 }
1150 return ret;
1151 }
1152
cgroup_bpf_query(struct cgroup * cgrp,const union bpf_attr * attr,union bpf_attr __user * uattr)1153 static int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
1154 union bpf_attr __user *uattr)
1155 {
1156 int ret;
1157
1158 cgroup_lock();
1159 ret = __cgroup_bpf_query(cgrp, attr, uattr);
1160 cgroup_unlock();
1161 return ret;
1162 }
1163
cgroup_bpf_prog_attach(const union bpf_attr * attr,enum bpf_prog_type ptype,struct bpf_prog * prog)1164 int cgroup_bpf_prog_attach(const union bpf_attr *attr,
1165 enum bpf_prog_type ptype, struct bpf_prog *prog)
1166 {
1167 struct bpf_prog *replace_prog = NULL;
1168 struct cgroup *cgrp;
1169 int ret;
1170
1171 cgrp = cgroup_get_from_fd(attr->target_fd);
1172 if (IS_ERR(cgrp))
1173 return PTR_ERR(cgrp);
1174
1175 if ((attr->attach_flags & BPF_F_ALLOW_MULTI) &&
1176 (attr->attach_flags & BPF_F_REPLACE)) {
1177 replace_prog = bpf_prog_get_type(attr->replace_bpf_fd, ptype);
1178 if (IS_ERR(replace_prog)) {
1179 cgroup_put(cgrp);
1180 return PTR_ERR(replace_prog);
1181 }
1182 }
1183
1184 ret = cgroup_bpf_attach(cgrp, prog, replace_prog, NULL,
1185 attr->attach_type, attr->attach_flags);
1186
1187 if (replace_prog)
1188 bpf_prog_put(replace_prog);
1189 cgroup_put(cgrp);
1190 return ret;
1191 }
1192
cgroup_bpf_prog_detach(const union bpf_attr * attr,enum bpf_prog_type ptype)1193 int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
1194 {
1195 struct bpf_prog *prog;
1196 struct cgroup *cgrp;
1197 int ret;
1198
1199 cgrp = cgroup_get_from_fd(attr->target_fd);
1200 if (IS_ERR(cgrp))
1201 return PTR_ERR(cgrp);
1202
1203 prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
1204 if (IS_ERR(prog))
1205 prog = NULL;
1206
1207 ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type);
1208 if (prog)
1209 bpf_prog_put(prog);
1210
1211 cgroup_put(cgrp);
1212 return ret;
1213 }
1214
bpf_cgroup_link_release(struct bpf_link * link)1215 static void bpf_cgroup_link_release(struct bpf_link *link)
1216 {
1217 struct bpf_cgroup_link *cg_link =
1218 container_of(link, struct bpf_cgroup_link, link);
1219 struct cgroup *cg;
1220
1221 /* link might have been auto-detached by dying cgroup already,
1222 * in that case our work is done here
1223 */
1224 if (!cg_link->cgroup)
1225 return;
1226
1227 cgroup_lock();
1228
1229 /* re-check cgroup under lock again */
1230 if (!cg_link->cgroup) {
1231 cgroup_unlock();
1232 return;
1233 }
1234
1235 WARN_ON(__cgroup_bpf_detach(cg_link->cgroup, NULL, cg_link,
1236 cg_link->type));
1237 if (cg_link->type == BPF_LSM_CGROUP)
1238 bpf_trampoline_unlink_cgroup_shim(cg_link->link.prog);
1239
1240 cg = cg_link->cgroup;
1241 cg_link->cgroup = NULL;
1242
1243 cgroup_unlock();
1244
1245 cgroup_put(cg);
1246 }
1247
bpf_cgroup_link_dealloc(struct bpf_link * link)1248 static void bpf_cgroup_link_dealloc(struct bpf_link *link)
1249 {
1250 struct bpf_cgroup_link *cg_link =
1251 container_of(link, struct bpf_cgroup_link, link);
1252
1253 kfree(cg_link);
1254 }
1255
bpf_cgroup_link_detach(struct bpf_link * link)1256 static int bpf_cgroup_link_detach(struct bpf_link *link)
1257 {
1258 bpf_cgroup_link_release(link);
1259
1260 return 0;
1261 }
1262
bpf_cgroup_link_show_fdinfo(const struct bpf_link * link,struct seq_file * seq)1263 static void bpf_cgroup_link_show_fdinfo(const struct bpf_link *link,
1264 struct seq_file *seq)
1265 {
1266 struct bpf_cgroup_link *cg_link =
1267 container_of(link, struct bpf_cgroup_link, link);
1268 u64 cg_id = 0;
1269
1270 cgroup_lock();
1271 if (cg_link->cgroup)
1272 cg_id = cgroup_id(cg_link->cgroup);
1273 cgroup_unlock();
1274
1275 seq_printf(seq,
1276 "cgroup_id:\t%llu\n"
1277 "attach_type:\t%d\n",
1278 cg_id,
1279 cg_link->type);
1280 }
1281
bpf_cgroup_link_fill_link_info(const struct bpf_link * link,struct bpf_link_info * info)1282 static int bpf_cgroup_link_fill_link_info(const struct bpf_link *link,
1283 struct bpf_link_info *info)
1284 {
1285 struct bpf_cgroup_link *cg_link =
1286 container_of(link, struct bpf_cgroup_link, link);
1287 u64 cg_id = 0;
1288
1289 cgroup_lock();
1290 if (cg_link->cgroup)
1291 cg_id = cgroup_id(cg_link->cgroup);
1292 cgroup_unlock();
1293
1294 info->cgroup.cgroup_id = cg_id;
1295 info->cgroup.attach_type = cg_link->type;
1296 return 0;
1297 }
1298
1299 static const struct bpf_link_ops bpf_cgroup_link_lops = {
1300 .release = bpf_cgroup_link_release,
1301 .dealloc = bpf_cgroup_link_dealloc,
1302 .detach = bpf_cgroup_link_detach,
1303 .update_prog = cgroup_bpf_replace,
1304 .show_fdinfo = bpf_cgroup_link_show_fdinfo,
1305 .fill_link_info = bpf_cgroup_link_fill_link_info,
1306 };
1307
cgroup_bpf_link_attach(const union bpf_attr * attr,struct bpf_prog * prog)1308 int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
1309 {
1310 struct bpf_link_primer link_primer;
1311 struct bpf_cgroup_link *link;
1312 struct cgroup *cgrp;
1313 int err;
1314
1315 if (attr->link_create.flags)
1316 return -EINVAL;
1317
1318 cgrp = cgroup_get_from_fd(attr->link_create.target_fd);
1319 if (IS_ERR(cgrp))
1320 return PTR_ERR(cgrp);
1321
1322 link = kzalloc(sizeof(*link), GFP_USER);
1323 if (!link) {
1324 err = -ENOMEM;
1325 goto out_put_cgroup;
1326 }
1327 bpf_link_init(&link->link, BPF_LINK_TYPE_CGROUP, &bpf_cgroup_link_lops,
1328 prog);
1329 link->cgroup = cgrp;
1330 link->type = attr->link_create.attach_type;
1331
1332 err = bpf_link_prime(&link->link, &link_primer);
1333 if (err) {
1334 kfree(link);
1335 goto out_put_cgroup;
1336 }
1337
1338 err = cgroup_bpf_attach(cgrp, NULL, NULL, link,
1339 link->type, BPF_F_ALLOW_MULTI);
1340 if (err) {
1341 bpf_link_cleanup(&link_primer);
1342 goto out_put_cgroup;
1343 }
1344
1345 return bpf_link_settle(&link_primer);
1346
1347 out_put_cgroup:
1348 cgroup_put(cgrp);
1349 return err;
1350 }
1351
cgroup_bpf_prog_query(const union bpf_attr * attr,union bpf_attr __user * uattr)1352 int cgroup_bpf_prog_query(const union bpf_attr *attr,
1353 union bpf_attr __user *uattr)
1354 {
1355 struct cgroup *cgrp;
1356 int ret;
1357
1358 cgrp = cgroup_get_from_fd(attr->query.target_fd);
1359 if (IS_ERR(cgrp))
1360 return PTR_ERR(cgrp);
1361
1362 ret = cgroup_bpf_query(cgrp, attr, uattr);
1363
1364 cgroup_put(cgrp);
1365 return ret;
1366 }
1367
1368 /**
1369 * __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
1370 * @sk: The socket sending or receiving traffic
1371 * @skb: The skb that is being sent or received
1372 * @atype: The type of program to be executed
1373 *
1374 * If no socket is passed, or the socket is not of type INET or INET6,
1375 * this function does nothing and returns 0.
1376 *
1377 * The program type passed in via @type must be suitable for network
1378 * filtering. No further check is performed to assert that.
1379 *
1380 * For egress packets, this function can return:
1381 * NET_XMIT_SUCCESS (0) - continue with packet output
1382 * NET_XMIT_DROP (1) - drop packet and notify TCP to call cwr
1383 * NET_XMIT_CN (2) - continue with packet output and notify TCP
1384 * to call cwr
1385 * -err - drop packet
1386 *
1387 * For ingress packets, this function will return -EPERM if any
1388 * attached program was found and if it returned != 1 during execution.
1389 * Otherwise 0 is returned.
1390 */
__cgroup_bpf_run_filter_skb(struct sock * sk,struct sk_buff * skb,enum cgroup_bpf_attach_type atype)1391 int __cgroup_bpf_run_filter_skb(struct sock *sk,
1392 struct sk_buff *skb,
1393 enum cgroup_bpf_attach_type atype)
1394 {
1395 unsigned int offset = -skb_network_offset(skb);
1396 struct sock *save_sk;
1397 void *saved_data_end;
1398 struct cgroup *cgrp;
1399 int ret;
1400
1401 if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
1402 return 0;
1403
1404 cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
1405 save_sk = skb->sk;
1406 skb->sk = sk;
1407 __skb_push(skb, offset);
1408
1409 /* compute pointers for the bpf prog */
1410 bpf_compute_and_save_data_end(skb, &saved_data_end);
1411
1412 if (atype == CGROUP_INET_EGRESS) {
1413 u32 flags = 0;
1414 bool cn;
1415
1416 ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, skb,
1417 __bpf_prog_run_save_cb, 0, &flags);
1418
1419 /* Return values of CGROUP EGRESS BPF programs are:
1420 * 0: drop packet
1421 * 1: keep packet
1422 * 2: drop packet and cn
1423 * 3: keep packet and cn
1424 *
1425 * The returned value is then converted to one of the NET_XMIT
1426 * or an error code that is then interpreted as drop packet
1427 * (and no cn):
1428 * 0: NET_XMIT_SUCCESS skb should be transmitted
1429 * 1: NET_XMIT_DROP skb should be dropped and cn
1430 * 2: NET_XMIT_CN skb should be transmitted and cn
1431 * 3: -err skb should be dropped
1432 */
1433
1434 cn = flags & BPF_RET_SET_CN;
1435 if (ret && !IS_ERR_VALUE((long)ret))
1436 ret = -EFAULT;
1437 if (!ret)
1438 ret = (cn ? NET_XMIT_CN : NET_XMIT_SUCCESS);
1439 else
1440 ret = (cn ? NET_XMIT_DROP : ret);
1441 } else {
1442 ret = bpf_prog_run_array_cg(&cgrp->bpf, atype,
1443 skb, __bpf_prog_run_save_cb, 0,
1444 NULL);
1445 if (ret && !IS_ERR_VALUE((long)ret))
1446 ret = -EFAULT;
1447 }
1448 bpf_restore_data_end(skb, saved_data_end);
1449 __skb_pull(skb, offset);
1450 skb->sk = save_sk;
1451
1452 return ret;
1453 }
1454 EXPORT_SYMBOL(__cgroup_bpf_run_filter_skb);
1455
1456 /**
1457 * __cgroup_bpf_run_filter_sk() - Run a program on a sock
1458 * @sk: sock structure to manipulate
1459 * @atype: The type of program to be executed
1460 *
1461 * socket is passed is expected to be of type INET or INET6.
1462 *
1463 * The program type passed in via @type must be suitable for sock
1464 * filtering. No further check is performed to assert that.
1465 *
1466 * This function will return %-EPERM if any if an attached program was found
1467 * and if it returned != 1 during execution. In all other cases, 0 is returned.
1468 */
__cgroup_bpf_run_filter_sk(struct sock * sk,enum cgroup_bpf_attach_type atype)1469 int __cgroup_bpf_run_filter_sk(struct sock *sk,
1470 enum cgroup_bpf_attach_type atype)
1471 {
1472 struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
1473
1474 return bpf_prog_run_array_cg(&cgrp->bpf, atype, sk, bpf_prog_run, 0,
1475 NULL);
1476 }
1477 EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
1478
1479 /**
1480 * __cgroup_bpf_run_filter_sock_addr() - Run a program on a sock and
1481 * provided by user sockaddr
1482 * @sk: sock struct that will use sockaddr
1483 * @uaddr: sockaddr struct provided by user
1484 * @uaddrlen: Pointer to the size of the sockaddr struct provided by user. It is
1485 * read-only for AF_INET[6] uaddr but can be modified for AF_UNIX
1486 * uaddr.
1487 * @atype: The type of program to be executed
1488 * @t_ctx: Pointer to attach type specific context
1489 * @flags: Pointer to u32 which contains higher bits of BPF program
1490 * return value (OR'ed together).
1491 *
1492 * socket is expected to be of type INET, INET6 or UNIX.
1493 *
1494 * This function will return %-EPERM if an attached program is found and
1495 * returned value != 1 during execution. In all other cases, 0 is returned.
1496 */
__cgroup_bpf_run_filter_sock_addr(struct sock * sk,struct sockaddr * uaddr,int * uaddrlen,enum cgroup_bpf_attach_type atype,void * t_ctx,u32 * flags)1497 int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
1498 struct sockaddr *uaddr,
1499 int *uaddrlen,
1500 enum cgroup_bpf_attach_type atype,
1501 void *t_ctx,
1502 u32 *flags)
1503 {
1504 struct bpf_sock_addr_kern ctx = {
1505 .sk = sk,
1506 .uaddr = uaddr,
1507 .t_ctx = t_ctx,
1508 };
1509 struct sockaddr_storage unspec;
1510 struct cgroup *cgrp;
1511 int ret;
1512
1513 /* Check socket family since not all sockets represent network
1514 * endpoint (e.g. AF_UNIX).
1515 */
1516 if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6 &&
1517 sk->sk_family != AF_UNIX)
1518 return 0;
1519
1520 if (!ctx.uaddr) {
1521 memset(&unspec, 0, sizeof(unspec));
1522 ctx.uaddr = (struct sockaddr *)&unspec;
1523 ctx.uaddrlen = 0;
1524 } else {
1525 ctx.uaddrlen = *uaddrlen;
1526 }
1527
1528 cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
1529 ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run,
1530 0, flags);
1531
1532 if (!ret && uaddr)
1533 *uaddrlen = ctx.uaddrlen;
1534
1535 return ret;
1536 }
1537 EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr);
1538
1539 /**
1540 * __cgroup_bpf_run_filter_sock_ops() - Run a program on a sock
1541 * @sk: socket to get cgroup from
1542 * @sock_ops: bpf_sock_ops_kern struct to pass to program. Contains
1543 * sk with connection information (IP addresses, etc.) May not contain
1544 * cgroup info if it is a req sock.
1545 * @atype: The type of program to be executed
1546 *
1547 * socket passed is expected to be of type INET or INET6.
1548 *
1549 * The program type passed in via @type must be suitable for sock_ops
1550 * filtering. No further check is performed to assert that.
1551 *
1552 * This function will return %-EPERM if any if an attached program was found
1553 * and if it returned != 1 during execution. In all other cases, 0 is returned.
1554 */
__cgroup_bpf_run_filter_sock_ops(struct sock * sk,struct bpf_sock_ops_kern * sock_ops,enum cgroup_bpf_attach_type atype)1555 int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
1556 struct bpf_sock_ops_kern *sock_ops,
1557 enum cgroup_bpf_attach_type atype)
1558 {
1559 struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
1560
1561 return bpf_prog_run_array_cg(&cgrp->bpf, atype, sock_ops, bpf_prog_run,
1562 0, NULL);
1563 }
1564 EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);
1565
__cgroup_bpf_check_dev_permission(short dev_type,u32 major,u32 minor,short access,enum cgroup_bpf_attach_type atype)1566 int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
1567 short access, enum cgroup_bpf_attach_type atype)
1568 {
1569 struct cgroup *cgrp;
1570 struct bpf_cgroup_dev_ctx ctx = {
1571 .access_type = (access << 16) | dev_type,
1572 .major = major,
1573 .minor = minor,
1574 };
1575 int ret;
1576
1577 rcu_read_lock();
1578 cgrp = task_dfl_cgroup(current);
1579 ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run, 0,
1580 NULL);
1581 rcu_read_unlock();
1582
1583 return ret;
1584 }
1585
BPF_CALL_2(bpf_get_local_storage,struct bpf_map *,map,u64,flags)1586 BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
1587 {
1588 /* flags argument is not used now,
1589 * but provides an ability to extend the API.
1590 * verifier checks that its value is correct.
1591 */
1592 enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
1593 struct bpf_cgroup_storage *storage;
1594 struct bpf_cg_run_ctx *ctx;
1595 void *ptr;
1596
1597 /* get current cgroup storage from BPF run context */
1598 ctx = container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx);
1599 storage = ctx->prog_item->cgroup_storage[stype];
1600
1601 if (stype == BPF_CGROUP_STORAGE_SHARED)
1602 ptr = &READ_ONCE(storage->buf)->data[0];
1603 else
1604 ptr = this_cpu_ptr(storage->percpu_buf);
1605
1606 return (unsigned long)ptr;
1607 }
1608
1609 const struct bpf_func_proto bpf_get_local_storage_proto = {
1610 .func = bpf_get_local_storage,
1611 .gpl_only = false,
1612 .ret_type = RET_PTR_TO_MAP_VALUE,
1613 .arg1_type = ARG_CONST_MAP_PTR,
1614 .arg2_type = ARG_ANYTHING,
1615 };
1616
BPF_CALL_0(bpf_get_retval)1617 BPF_CALL_0(bpf_get_retval)
1618 {
1619 struct bpf_cg_run_ctx *ctx =
1620 container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx);
1621
1622 return ctx->retval;
1623 }
1624
1625 const struct bpf_func_proto bpf_get_retval_proto = {
1626 .func = bpf_get_retval,
1627 .gpl_only = false,
1628 .ret_type = RET_INTEGER,
1629 };
1630
BPF_CALL_1(bpf_set_retval,int,retval)1631 BPF_CALL_1(bpf_set_retval, int, retval)
1632 {
1633 struct bpf_cg_run_ctx *ctx =
1634 container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx);
1635
1636 ctx->retval = retval;
1637 return 0;
1638 }
1639
1640 const struct bpf_func_proto bpf_set_retval_proto = {
1641 .func = bpf_set_retval,
1642 .gpl_only = false,
1643 .ret_type = RET_INTEGER,
1644 .arg1_type = ARG_ANYTHING,
1645 };
1646
1647 static const struct bpf_func_proto *
cgroup_dev_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)1648 cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
1649 {
1650 const struct bpf_func_proto *func_proto;
1651
1652 func_proto = cgroup_common_func_proto(func_id, prog);
1653 if (func_proto)
1654 return func_proto;
1655
1656 func_proto = cgroup_current_func_proto(func_id, prog);
1657 if (func_proto)
1658 return func_proto;
1659
1660 switch (func_id) {
1661 case BPF_FUNC_perf_event_output:
1662 return &bpf_event_output_data_proto;
1663 default:
1664 return bpf_base_func_proto(func_id, prog);
1665 }
1666 }
1667
cgroup_dev_is_valid_access(int off,int size,enum bpf_access_type type,const struct bpf_prog * prog,struct bpf_insn_access_aux * info)1668 static bool cgroup_dev_is_valid_access(int off, int size,
1669 enum bpf_access_type type,
1670 const struct bpf_prog *prog,
1671 struct bpf_insn_access_aux *info)
1672 {
1673 const int size_default = sizeof(__u32);
1674
1675 if (type == BPF_WRITE)
1676 return false;
1677
1678 if (off < 0 || off + size > sizeof(struct bpf_cgroup_dev_ctx))
1679 return false;
1680 /* The verifier guarantees that size > 0. */
1681 if (off % size != 0)
1682 return false;
1683
1684 switch (off) {
1685 case bpf_ctx_range(struct bpf_cgroup_dev_ctx, access_type):
1686 bpf_ctx_record_field_size(info, size_default);
1687 if (!bpf_ctx_narrow_access_ok(off, size, size_default))
1688 return false;
1689 break;
1690 default:
1691 if (size != size_default)
1692 return false;
1693 }
1694
1695 return true;
1696 }
1697
1698 const struct bpf_prog_ops cg_dev_prog_ops = {
1699 };
1700
1701 const struct bpf_verifier_ops cg_dev_verifier_ops = {
1702 .get_func_proto = cgroup_dev_func_proto,
1703 .is_valid_access = cgroup_dev_is_valid_access,
1704 };
1705
1706 /**
1707 * __cgroup_bpf_run_filter_sysctl - Run a program on sysctl
1708 *
1709 * @head: sysctl table header
1710 * @table: sysctl table
1711 * @write: sysctl is being read (= 0) or written (= 1)
1712 * @buf: pointer to buffer (in and out)
1713 * @pcount: value-result argument: value is size of buffer pointed to by @buf,
1714 * result is size of @new_buf if program set new value, initial value
1715 * otherwise
1716 * @ppos: value-result argument: value is position at which read from or write
1717 * to sysctl is happening, result is new position if program overrode it,
1718 * initial value otherwise
1719 * @atype: type of program to be executed
1720 *
1721 * Program is run when sysctl is being accessed, either read or written, and
1722 * can allow or deny such access.
1723 *
1724 * This function will return %-EPERM if an attached program is found and
1725 * returned value != 1 during execution. In all other cases 0 is returned.
1726 */
__cgroup_bpf_run_filter_sysctl(struct ctl_table_header * head,const struct ctl_table * table,int write,char ** buf,size_t * pcount,loff_t * ppos,enum cgroup_bpf_attach_type atype)1727 int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
1728 const struct ctl_table *table, int write,
1729 char **buf, size_t *pcount, loff_t *ppos,
1730 enum cgroup_bpf_attach_type atype)
1731 {
1732 struct bpf_sysctl_kern ctx = {
1733 .head = head,
1734 .table = table,
1735 .write = write,
1736 .ppos = ppos,
1737 .cur_val = NULL,
1738 .cur_len = PAGE_SIZE,
1739 .new_val = NULL,
1740 .new_len = 0,
1741 .new_updated = 0,
1742 };
1743 struct cgroup *cgrp;
1744 loff_t pos = 0;
1745 int ret;
1746
1747 ctx.cur_val = kmalloc_track_caller(ctx.cur_len, GFP_KERNEL);
1748 if (!ctx.cur_val ||
1749 table->proc_handler(table, 0, ctx.cur_val, &ctx.cur_len, &pos)) {
1750 /* Let BPF program decide how to proceed. */
1751 ctx.cur_len = 0;
1752 }
1753
1754 if (write && *buf && *pcount) {
1755 /* BPF program should be able to override new value with a
1756 * buffer bigger than provided by user.
1757 */
1758 ctx.new_val = kmalloc_track_caller(PAGE_SIZE, GFP_KERNEL);
1759 ctx.new_len = min_t(size_t, PAGE_SIZE, *pcount);
1760 if (ctx.new_val) {
1761 memcpy(ctx.new_val, *buf, ctx.new_len);
1762 } else {
1763 /* Let BPF program decide how to proceed. */
1764 ctx.new_len = 0;
1765 }
1766 }
1767
1768 rcu_read_lock();
1769 cgrp = task_dfl_cgroup(current);
1770 ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run, 0,
1771 NULL);
1772 rcu_read_unlock();
1773
1774 kfree(ctx.cur_val);
1775
1776 if (ret == 1 && ctx.new_updated) {
1777 kfree(*buf);
1778 *buf = ctx.new_val;
1779 *pcount = ctx.new_len;
1780 } else {
1781 kfree(ctx.new_val);
1782 }
1783
1784 return ret;
1785 }
1786
1787 #ifdef CONFIG_NET
sockopt_alloc_buf(struct bpf_sockopt_kern * ctx,int max_optlen,struct bpf_sockopt_buf * buf)1788 static int sockopt_alloc_buf(struct bpf_sockopt_kern *ctx, int max_optlen,
1789 struct bpf_sockopt_buf *buf)
1790 {
1791 if (unlikely(max_optlen < 0))
1792 return -EINVAL;
1793
1794 if (unlikely(max_optlen > PAGE_SIZE)) {
1795 /* We don't expose optvals that are greater than PAGE_SIZE
1796 * to the BPF program.
1797 */
1798 max_optlen = PAGE_SIZE;
1799 }
1800
1801 if (max_optlen <= sizeof(buf->data)) {
1802 /* When the optval fits into BPF_SOCKOPT_KERN_BUF_SIZE
1803 * bytes avoid the cost of kzalloc.
1804 */
1805 ctx->optval = buf->data;
1806 ctx->optval_end = ctx->optval + max_optlen;
1807 return max_optlen;
1808 }
1809
1810 ctx->optval = kzalloc(max_optlen, GFP_USER);
1811 if (!ctx->optval)
1812 return -ENOMEM;
1813
1814 ctx->optval_end = ctx->optval + max_optlen;
1815
1816 return max_optlen;
1817 }
1818
sockopt_free_buf(struct bpf_sockopt_kern * ctx,struct bpf_sockopt_buf * buf)1819 static void sockopt_free_buf(struct bpf_sockopt_kern *ctx,
1820 struct bpf_sockopt_buf *buf)
1821 {
1822 if (ctx->optval == buf->data)
1823 return;
1824 kfree(ctx->optval);
1825 }
1826
sockopt_buf_allocated(struct bpf_sockopt_kern * ctx,struct bpf_sockopt_buf * buf)1827 static bool sockopt_buf_allocated(struct bpf_sockopt_kern *ctx,
1828 struct bpf_sockopt_buf *buf)
1829 {
1830 return ctx->optval != buf->data;
1831 }
1832
__cgroup_bpf_run_filter_setsockopt(struct sock * sk,int * level,int * optname,sockptr_t optval,int * optlen,char ** kernel_optval)1833 int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int *level,
1834 int *optname, sockptr_t optval,
1835 int *optlen, char **kernel_optval)
1836 {
1837 struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
1838 struct bpf_sockopt_buf buf = {};
1839 struct bpf_sockopt_kern ctx = {
1840 .sk = sk,
1841 .level = *level,
1842 .optname = *optname,
1843 };
1844 int ret, max_optlen;
1845
1846 /* Allocate a bit more than the initial user buffer for
1847 * BPF program. The canonical use case is overriding
1848 * TCP_CONGESTION(nv) to TCP_CONGESTION(cubic).
1849 */
1850 max_optlen = max_t(int, 16, *optlen);
1851 max_optlen = sockopt_alloc_buf(&ctx, max_optlen, &buf);
1852 if (max_optlen < 0)
1853 return max_optlen;
1854
1855 ctx.optlen = *optlen;
1856
1857 if (copy_from_sockptr(ctx.optval, optval,
1858 min(*optlen, max_optlen))) {
1859 ret = -EFAULT;
1860 goto out;
1861 }
1862
1863 lock_sock(sk);
1864 ret = bpf_prog_run_array_cg(&cgrp->bpf, CGROUP_SETSOCKOPT,
1865 &ctx, bpf_prog_run, 0, NULL);
1866 release_sock(sk);
1867
1868 if (ret)
1869 goto out;
1870
1871 if (ctx.optlen == -1) {
1872 /* optlen set to -1, bypass kernel */
1873 ret = 1;
1874 } else if (ctx.optlen > max_optlen || ctx.optlen < -1) {
1875 /* optlen is out of bounds */
1876 if (*optlen > PAGE_SIZE && ctx.optlen >= 0) {
1877 pr_info_once("bpf setsockopt: ignoring program buffer with optlen=%d (max_optlen=%d)\n",
1878 ctx.optlen, max_optlen);
1879 ret = 0;
1880 goto out;
1881 }
1882 ret = -EFAULT;
1883 } else {
1884 /* optlen within bounds, run kernel handler */
1885 ret = 0;
1886
1887 /* export any potential modifications */
1888 *level = ctx.level;
1889 *optname = ctx.optname;
1890
1891 /* optlen == 0 from BPF indicates that we should
1892 * use original userspace data.
1893 */
1894 if (ctx.optlen != 0) {
1895 *optlen = ctx.optlen;
1896 /* We've used bpf_sockopt_kern->buf as an intermediary
1897 * storage, but the BPF program indicates that we need
1898 * to pass this data to the kernel setsockopt handler.
1899 * No way to export on-stack buf, have to allocate a
1900 * new buffer.
1901 */
1902 if (!sockopt_buf_allocated(&ctx, &buf)) {
1903 void *p = kmalloc(ctx.optlen, GFP_USER);
1904
1905 if (!p) {
1906 ret = -ENOMEM;
1907 goto out;
1908 }
1909 memcpy(p, ctx.optval, ctx.optlen);
1910 *kernel_optval = p;
1911 } else {
1912 *kernel_optval = ctx.optval;
1913 }
1914 /* export and don't free sockopt buf */
1915 return 0;
1916 }
1917 }
1918
1919 out:
1920 sockopt_free_buf(&ctx, &buf);
1921 return ret;
1922 }
1923
__cgroup_bpf_run_filter_getsockopt(struct sock * sk,int level,int optname,sockptr_t optval,sockptr_t optlen,int max_optlen,int retval)1924 int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
1925 int optname, sockptr_t optval,
1926 sockptr_t optlen, int max_optlen,
1927 int retval)
1928 {
1929 struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
1930 struct bpf_sockopt_buf buf = {};
1931 struct bpf_sockopt_kern ctx = {
1932 .sk = sk,
1933 .level = level,
1934 .optname = optname,
1935 .current_task = current,
1936 };
1937 int orig_optlen;
1938 int ret;
1939
1940 orig_optlen = max_optlen;
1941 ctx.optlen = max_optlen;
1942 max_optlen = sockopt_alloc_buf(&ctx, max_optlen, &buf);
1943 if (max_optlen < 0)
1944 return max_optlen;
1945
1946 if (!retval) {
1947 /* If kernel getsockopt finished successfully,
1948 * copy whatever was returned to the user back
1949 * into our temporary buffer. Set optlen to the
1950 * one that kernel returned as well to let
1951 * BPF programs inspect the value.
1952 */
1953 if (copy_from_sockptr(&ctx.optlen, optlen,
1954 sizeof(ctx.optlen))) {
1955 ret = -EFAULT;
1956 goto out;
1957 }
1958
1959 if (ctx.optlen < 0) {
1960 ret = -EFAULT;
1961 goto out;
1962 }
1963 orig_optlen = ctx.optlen;
1964
1965 if (copy_from_sockptr(ctx.optval, optval,
1966 min(ctx.optlen, max_optlen))) {
1967 ret = -EFAULT;
1968 goto out;
1969 }
1970 }
1971
1972 lock_sock(sk);
1973 ret = bpf_prog_run_array_cg(&cgrp->bpf, CGROUP_GETSOCKOPT,
1974 &ctx, bpf_prog_run, retval, NULL);
1975 release_sock(sk);
1976
1977 if (ret < 0)
1978 goto out;
1979
1980 if (!sockptr_is_null(optval) &&
1981 (ctx.optlen > max_optlen || ctx.optlen < 0)) {
1982 if (orig_optlen > PAGE_SIZE && ctx.optlen >= 0) {
1983 pr_info_once("bpf getsockopt: ignoring program buffer with optlen=%d (max_optlen=%d)\n",
1984 ctx.optlen, max_optlen);
1985 ret = retval;
1986 goto out;
1987 }
1988 ret = -EFAULT;
1989 goto out;
1990 }
1991
1992 if (ctx.optlen != 0) {
1993 if (!sockptr_is_null(optval) &&
1994 copy_to_sockptr(optval, ctx.optval, ctx.optlen)) {
1995 ret = -EFAULT;
1996 goto out;
1997 }
1998 if (copy_to_sockptr(optlen, &ctx.optlen, sizeof(ctx.optlen))) {
1999 ret = -EFAULT;
2000 goto out;
2001 }
2002 }
2003
2004 out:
2005 sockopt_free_buf(&ctx, &buf);
2006 return ret;
2007 }
2008
__cgroup_bpf_run_filter_getsockopt_kern(struct sock * sk,int level,int optname,void * optval,int * optlen,int retval)2009 int __cgroup_bpf_run_filter_getsockopt_kern(struct sock *sk, int level,
2010 int optname, void *optval,
2011 int *optlen, int retval)
2012 {
2013 struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
2014 struct bpf_sockopt_kern ctx = {
2015 .sk = sk,
2016 .level = level,
2017 .optname = optname,
2018 .optlen = *optlen,
2019 .optval = optval,
2020 .optval_end = optval + *optlen,
2021 .current_task = current,
2022 };
2023 int ret;
2024
2025 /* Note that __cgroup_bpf_run_filter_getsockopt doesn't copy
2026 * user data back into BPF buffer when reval != 0. This is
2027 * done as an optimization to avoid extra copy, assuming
2028 * kernel won't populate the data in case of an error.
2029 * Here we always pass the data and memset() should
2030 * be called if that data shouldn't be "exported".
2031 */
2032
2033 ret = bpf_prog_run_array_cg(&cgrp->bpf, CGROUP_GETSOCKOPT,
2034 &ctx, bpf_prog_run, retval, NULL);
2035 if (ret < 0)
2036 return ret;
2037
2038 if (ctx.optlen > *optlen)
2039 return -EFAULT;
2040
2041 /* BPF programs can shrink the buffer, export the modifications.
2042 */
2043 if (ctx.optlen != 0)
2044 *optlen = ctx.optlen;
2045
2046 return ret;
2047 }
2048 #endif
2049
sysctl_cpy_dir(const struct ctl_dir * dir,char ** bufp,size_t * lenp)2050 static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
2051 size_t *lenp)
2052 {
2053 ssize_t tmp_ret = 0, ret;
2054
2055 if (dir->header.parent) {
2056 tmp_ret = sysctl_cpy_dir(dir->header.parent, bufp, lenp);
2057 if (tmp_ret < 0)
2058 return tmp_ret;
2059 }
2060
2061 ret = strscpy(*bufp, dir->header.ctl_table[0].procname, *lenp);
2062 if (ret < 0)
2063 return ret;
2064 *bufp += ret;
2065 *lenp -= ret;
2066 ret += tmp_ret;
2067
2068 /* Avoid leading slash. */
2069 if (!ret)
2070 return ret;
2071
2072 tmp_ret = strscpy(*bufp, "/", *lenp);
2073 if (tmp_ret < 0)
2074 return tmp_ret;
2075 *bufp += tmp_ret;
2076 *lenp -= tmp_ret;
2077
2078 return ret + tmp_ret;
2079 }
2080
BPF_CALL_4(bpf_sysctl_get_name,struct bpf_sysctl_kern *,ctx,char *,buf,size_t,buf_len,u64,flags)2081 BPF_CALL_4(bpf_sysctl_get_name, struct bpf_sysctl_kern *, ctx, char *, buf,
2082 size_t, buf_len, u64, flags)
2083 {
2084 ssize_t tmp_ret = 0, ret;
2085
2086 if (!buf)
2087 return -EINVAL;
2088
2089 if (!(flags & BPF_F_SYSCTL_BASE_NAME)) {
2090 if (!ctx->head)
2091 return -EINVAL;
2092 tmp_ret = sysctl_cpy_dir(ctx->head->parent, &buf, &buf_len);
2093 if (tmp_ret < 0)
2094 return tmp_ret;
2095 }
2096
2097 ret = strscpy(buf, ctx->table->procname, buf_len);
2098
2099 return ret < 0 ? ret : tmp_ret + ret;
2100 }
2101
2102 static const struct bpf_func_proto bpf_sysctl_get_name_proto = {
2103 .func = bpf_sysctl_get_name,
2104 .gpl_only = false,
2105 .ret_type = RET_INTEGER,
2106 .arg1_type = ARG_PTR_TO_CTX,
2107 .arg2_type = ARG_PTR_TO_MEM,
2108 .arg3_type = ARG_CONST_SIZE,
2109 .arg4_type = ARG_ANYTHING,
2110 };
2111
copy_sysctl_value(char * dst,size_t dst_len,char * src,size_t src_len)2112 static int copy_sysctl_value(char *dst, size_t dst_len, char *src,
2113 size_t src_len)
2114 {
2115 if (!dst)
2116 return -EINVAL;
2117
2118 if (!dst_len)
2119 return -E2BIG;
2120
2121 if (!src || !src_len) {
2122 memset(dst, 0, dst_len);
2123 return -EINVAL;
2124 }
2125
2126 memcpy(dst, src, min(dst_len, src_len));
2127
2128 if (dst_len > src_len) {
2129 memset(dst + src_len, '\0', dst_len - src_len);
2130 return src_len;
2131 }
2132
2133 dst[dst_len - 1] = '\0';
2134
2135 return -E2BIG;
2136 }
2137
BPF_CALL_3(bpf_sysctl_get_current_value,struct bpf_sysctl_kern *,ctx,char *,buf,size_t,buf_len)2138 BPF_CALL_3(bpf_sysctl_get_current_value, struct bpf_sysctl_kern *, ctx,
2139 char *, buf, size_t, buf_len)
2140 {
2141 return copy_sysctl_value(buf, buf_len, ctx->cur_val, ctx->cur_len);
2142 }
2143
2144 static const struct bpf_func_proto bpf_sysctl_get_current_value_proto = {
2145 .func = bpf_sysctl_get_current_value,
2146 .gpl_only = false,
2147 .ret_type = RET_INTEGER,
2148 .arg1_type = ARG_PTR_TO_CTX,
2149 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
2150 .arg3_type = ARG_CONST_SIZE,
2151 };
2152
BPF_CALL_3(bpf_sysctl_get_new_value,struct bpf_sysctl_kern *,ctx,char *,buf,size_t,buf_len)2153 BPF_CALL_3(bpf_sysctl_get_new_value, struct bpf_sysctl_kern *, ctx, char *, buf,
2154 size_t, buf_len)
2155 {
2156 if (!ctx->write) {
2157 if (buf && buf_len)
2158 memset(buf, '\0', buf_len);
2159 return -EINVAL;
2160 }
2161 return copy_sysctl_value(buf, buf_len, ctx->new_val, ctx->new_len);
2162 }
2163
2164 static const struct bpf_func_proto bpf_sysctl_get_new_value_proto = {
2165 .func = bpf_sysctl_get_new_value,
2166 .gpl_only = false,
2167 .ret_type = RET_INTEGER,
2168 .arg1_type = ARG_PTR_TO_CTX,
2169 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
2170 .arg3_type = ARG_CONST_SIZE,
2171 };
2172
BPF_CALL_3(bpf_sysctl_set_new_value,struct bpf_sysctl_kern *,ctx,const char *,buf,size_t,buf_len)2173 BPF_CALL_3(bpf_sysctl_set_new_value, struct bpf_sysctl_kern *, ctx,
2174 const char *, buf, size_t, buf_len)
2175 {
2176 if (!ctx->write || !ctx->new_val || !ctx->new_len || !buf || !buf_len)
2177 return -EINVAL;
2178
2179 if (buf_len > PAGE_SIZE - 1)
2180 return -E2BIG;
2181
2182 memcpy(ctx->new_val, buf, buf_len);
2183 ctx->new_len = buf_len;
2184 ctx->new_updated = 1;
2185
2186 return 0;
2187 }
2188
2189 static const struct bpf_func_proto bpf_sysctl_set_new_value_proto = {
2190 .func = bpf_sysctl_set_new_value,
2191 .gpl_only = false,
2192 .ret_type = RET_INTEGER,
2193 .arg1_type = ARG_PTR_TO_CTX,
2194 .arg2_type = ARG_PTR_TO_MEM | MEM_RDONLY,
2195 .arg3_type = ARG_CONST_SIZE,
2196 };
2197
2198 static const struct bpf_func_proto *
sysctl_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)2199 sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
2200 {
2201 const struct bpf_func_proto *func_proto;
2202
2203 func_proto = cgroup_common_func_proto(func_id, prog);
2204 if (func_proto)
2205 return func_proto;
2206
2207 func_proto = cgroup_current_func_proto(func_id, prog);
2208 if (func_proto)
2209 return func_proto;
2210
2211 switch (func_id) {
2212 case BPF_FUNC_sysctl_get_name:
2213 return &bpf_sysctl_get_name_proto;
2214 case BPF_FUNC_sysctl_get_current_value:
2215 return &bpf_sysctl_get_current_value_proto;
2216 case BPF_FUNC_sysctl_get_new_value:
2217 return &bpf_sysctl_get_new_value_proto;
2218 case BPF_FUNC_sysctl_set_new_value:
2219 return &bpf_sysctl_set_new_value_proto;
2220 case BPF_FUNC_ktime_get_coarse_ns:
2221 return &bpf_ktime_get_coarse_ns_proto;
2222 case BPF_FUNC_perf_event_output:
2223 return &bpf_event_output_data_proto;
2224 default:
2225 return bpf_base_func_proto(func_id, prog);
2226 }
2227 }
2228
sysctl_is_valid_access(int off,int size,enum bpf_access_type type,const struct bpf_prog * prog,struct bpf_insn_access_aux * info)2229 static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,
2230 const struct bpf_prog *prog,
2231 struct bpf_insn_access_aux *info)
2232 {
2233 const int size_default = sizeof(__u32);
2234
2235 if (off < 0 || off + size > sizeof(struct bpf_sysctl) || off % size)
2236 return false;
2237
2238 switch (off) {
2239 case bpf_ctx_range(struct bpf_sysctl, write):
2240 if (type != BPF_READ)
2241 return false;
2242 bpf_ctx_record_field_size(info, size_default);
2243 return bpf_ctx_narrow_access_ok(off, size, size_default);
2244 case bpf_ctx_range(struct bpf_sysctl, file_pos):
2245 if (type == BPF_READ) {
2246 bpf_ctx_record_field_size(info, size_default);
2247 return bpf_ctx_narrow_access_ok(off, size, size_default);
2248 } else {
2249 return size == size_default;
2250 }
2251 default:
2252 return false;
2253 }
2254 }
2255
sysctl_convert_ctx_access(enum bpf_access_type type,const struct bpf_insn * si,struct bpf_insn * insn_buf,struct bpf_prog * prog,u32 * target_size)2256 static u32 sysctl_convert_ctx_access(enum bpf_access_type type,
2257 const struct bpf_insn *si,
2258 struct bpf_insn *insn_buf,
2259 struct bpf_prog *prog, u32 *target_size)
2260 {
2261 struct bpf_insn *insn = insn_buf;
2262 u32 read_size;
2263
2264 switch (si->off) {
2265 case offsetof(struct bpf_sysctl, write):
2266 *insn++ = BPF_LDX_MEM(
2267 BPF_SIZE(si->code), si->dst_reg, si->src_reg,
2268 bpf_target_off(struct bpf_sysctl_kern, write,
2269 sizeof_field(struct bpf_sysctl_kern,
2270 write),
2271 target_size));
2272 break;
2273 case offsetof(struct bpf_sysctl, file_pos):
2274 /* ppos is a pointer so it should be accessed via indirect
2275 * loads and stores. Also for stores additional temporary
2276 * register is used since neither src_reg nor dst_reg can be
2277 * overridden.
2278 */
2279 if (type == BPF_WRITE) {
2280 int treg = BPF_REG_9;
2281
2282 if (si->src_reg == treg || si->dst_reg == treg)
2283 --treg;
2284 if (si->src_reg == treg || si->dst_reg == treg)
2285 --treg;
2286 *insn++ = BPF_STX_MEM(
2287 BPF_DW, si->dst_reg, treg,
2288 offsetof(struct bpf_sysctl_kern, tmp_reg));
2289 *insn++ = BPF_LDX_MEM(
2290 BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
2291 treg, si->dst_reg,
2292 offsetof(struct bpf_sysctl_kern, ppos));
2293 *insn++ = BPF_RAW_INSN(
2294 BPF_CLASS(si->code) | BPF_MEM | BPF_SIZEOF(u32),
2295 treg, si->src_reg,
2296 bpf_ctx_narrow_access_offset(
2297 0, sizeof(u32), sizeof(loff_t)),
2298 si->imm);
2299 *insn++ = BPF_LDX_MEM(
2300 BPF_DW, treg, si->dst_reg,
2301 offsetof(struct bpf_sysctl_kern, tmp_reg));
2302 } else {
2303 *insn++ = BPF_LDX_MEM(
2304 BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
2305 si->dst_reg, si->src_reg,
2306 offsetof(struct bpf_sysctl_kern, ppos));
2307 read_size = bpf_size_to_bytes(BPF_SIZE(si->code));
2308 *insn++ = BPF_LDX_MEM(
2309 BPF_SIZE(si->code), si->dst_reg, si->dst_reg,
2310 bpf_ctx_narrow_access_offset(
2311 0, read_size, sizeof(loff_t)));
2312 }
2313 *target_size = sizeof(u32);
2314 break;
2315 }
2316
2317 return insn - insn_buf;
2318 }
2319
2320 const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
2321 .get_func_proto = sysctl_func_proto,
2322 .is_valid_access = sysctl_is_valid_access,
2323 .convert_ctx_access = sysctl_convert_ctx_access,
2324 };
2325
2326 const struct bpf_prog_ops cg_sysctl_prog_ops = {
2327 };
2328
2329 #ifdef CONFIG_NET
BPF_CALL_1(bpf_get_netns_cookie_sockopt,struct bpf_sockopt_kern *,ctx)2330 BPF_CALL_1(bpf_get_netns_cookie_sockopt, struct bpf_sockopt_kern *, ctx)
2331 {
2332 const struct net *net = ctx ? sock_net(ctx->sk) : &init_net;
2333
2334 return net->net_cookie;
2335 }
2336
2337 static const struct bpf_func_proto bpf_get_netns_cookie_sockopt_proto = {
2338 .func = bpf_get_netns_cookie_sockopt,
2339 .gpl_only = false,
2340 .ret_type = RET_INTEGER,
2341 .arg1_type = ARG_PTR_TO_CTX_OR_NULL,
2342 };
2343 #endif
2344
2345 static const struct bpf_func_proto *
cg_sockopt_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)2346 cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
2347 {
2348 const struct bpf_func_proto *func_proto;
2349
2350 func_proto = cgroup_common_func_proto(func_id, prog);
2351 if (func_proto)
2352 return func_proto;
2353
2354 func_proto = cgroup_current_func_proto(func_id, prog);
2355 if (func_proto)
2356 return func_proto;
2357
2358 switch (func_id) {
2359 #ifdef CONFIG_NET
2360 case BPF_FUNC_get_netns_cookie:
2361 return &bpf_get_netns_cookie_sockopt_proto;
2362 case BPF_FUNC_sk_storage_get:
2363 return &bpf_sk_storage_get_proto;
2364 case BPF_FUNC_sk_storage_delete:
2365 return &bpf_sk_storage_delete_proto;
2366 case BPF_FUNC_setsockopt:
2367 if (prog->expected_attach_type == BPF_CGROUP_SETSOCKOPT)
2368 return &bpf_sk_setsockopt_proto;
2369 return NULL;
2370 case BPF_FUNC_getsockopt:
2371 if (prog->expected_attach_type == BPF_CGROUP_SETSOCKOPT)
2372 return &bpf_sk_getsockopt_proto;
2373 return NULL;
2374 #endif
2375 #ifdef CONFIG_INET
2376 case BPF_FUNC_tcp_sock:
2377 return &bpf_tcp_sock_proto;
2378 #endif
2379 case BPF_FUNC_perf_event_output:
2380 return &bpf_event_output_data_proto;
2381 default:
2382 return bpf_base_func_proto(func_id, prog);
2383 }
2384 }
2385
cg_sockopt_is_valid_access(int off,int size,enum bpf_access_type type,const struct bpf_prog * prog,struct bpf_insn_access_aux * info)2386 static bool cg_sockopt_is_valid_access(int off, int size,
2387 enum bpf_access_type type,
2388 const struct bpf_prog *prog,
2389 struct bpf_insn_access_aux *info)
2390 {
2391 const int size_default = sizeof(__u32);
2392
2393 if (off < 0 || off >= sizeof(struct bpf_sockopt))
2394 return false;
2395
2396 if (off % size != 0)
2397 return false;
2398
2399 if (type == BPF_WRITE) {
2400 switch (off) {
2401 case offsetof(struct bpf_sockopt, retval):
2402 if (size != size_default)
2403 return false;
2404 return prog->expected_attach_type ==
2405 BPF_CGROUP_GETSOCKOPT;
2406 case offsetof(struct bpf_sockopt, optname):
2407 fallthrough;
2408 case offsetof(struct bpf_sockopt, level):
2409 if (size != size_default)
2410 return false;
2411 return prog->expected_attach_type ==
2412 BPF_CGROUP_SETSOCKOPT;
2413 case offsetof(struct bpf_sockopt, optlen):
2414 return size == size_default;
2415 default:
2416 return false;
2417 }
2418 }
2419
2420 switch (off) {
2421 case offsetof(struct bpf_sockopt, sk):
2422 if (size != sizeof(__u64))
2423 return false;
2424 info->reg_type = PTR_TO_SOCKET;
2425 break;
2426 case offsetof(struct bpf_sockopt, optval):
2427 if (size != sizeof(__u64))
2428 return false;
2429 info->reg_type = PTR_TO_PACKET;
2430 break;
2431 case offsetof(struct bpf_sockopt, optval_end):
2432 if (size != sizeof(__u64))
2433 return false;
2434 info->reg_type = PTR_TO_PACKET_END;
2435 break;
2436 case offsetof(struct bpf_sockopt, retval):
2437 if (size != size_default)
2438 return false;
2439 return prog->expected_attach_type == BPF_CGROUP_GETSOCKOPT;
2440 default:
2441 if (size != size_default)
2442 return false;
2443 break;
2444 }
2445 return true;
2446 }
2447
2448 #define CG_SOCKOPT_READ_FIELD(F) \
2449 BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, F), \
2450 si->dst_reg, si->src_reg, \
2451 offsetof(struct bpf_sockopt_kern, F))
2452
2453 #define CG_SOCKOPT_WRITE_FIELD(F) \
2454 BPF_RAW_INSN((BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, F) | \
2455 BPF_MEM | BPF_CLASS(si->code)), \
2456 si->dst_reg, si->src_reg, \
2457 offsetof(struct bpf_sockopt_kern, F), \
2458 si->imm)
2459
cg_sockopt_convert_ctx_access(enum bpf_access_type type,const struct bpf_insn * si,struct bpf_insn * insn_buf,struct bpf_prog * prog,u32 * target_size)2460 static u32 cg_sockopt_convert_ctx_access(enum bpf_access_type type,
2461 const struct bpf_insn *si,
2462 struct bpf_insn *insn_buf,
2463 struct bpf_prog *prog,
2464 u32 *target_size)
2465 {
2466 struct bpf_insn *insn = insn_buf;
2467
2468 switch (si->off) {
2469 case offsetof(struct bpf_sockopt, sk):
2470 *insn++ = CG_SOCKOPT_READ_FIELD(sk);
2471 break;
2472 case offsetof(struct bpf_sockopt, level):
2473 if (type == BPF_WRITE)
2474 *insn++ = CG_SOCKOPT_WRITE_FIELD(level);
2475 else
2476 *insn++ = CG_SOCKOPT_READ_FIELD(level);
2477 break;
2478 case offsetof(struct bpf_sockopt, optname):
2479 if (type == BPF_WRITE)
2480 *insn++ = CG_SOCKOPT_WRITE_FIELD(optname);
2481 else
2482 *insn++ = CG_SOCKOPT_READ_FIELD(optname);
2483 break;
2484 case offsetof(struct bpf_sockopt, optlen):
2485 if (type == BPF_WRITE)
2486 *insn++ = CG_SOCKOPT_WRITE_FIELD(optlen);
2487 else
2488 *insn++ = CG_SOCKOPT_READ_FIELD(optlen);
2489 break;
2490 case offsetof(struct bpf_sockopt, retval):
2491 BUILD_BUG_ON(offsetof(struct bpf_cg_run_ctx, run_ctx) != 0);
2492
2493 if (type == BPF_WRITE) {
2494 int treg = BPF_REG_9;
2495
2496 if (si->src_reg == treg || si->dst_reg == treg)
2497 --treg;
2498 if (si->src_reg == treg || si->dst_reg == treg)
2499 --treg;
2500 *insn++ = BPF_STX_MEM(BPF_DW, si->dst_reg, treg,
2501 offsetof(struct bpf_sockopt_kern, tmp_reg));
2502 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, current_task),
2503 treg, si->dst_reg,
2504 offsetof(struct bpf_sockopt_kern, current_task));
2505 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct task_struct, bpf_ctx),
2506 treg, treg,
2507 offsetof(struct task_struct, bpf_ctx));
2508 *insn++ = BPF_RAW_INSN(BPF_CLASS(si->code) | BPF_MEM |
2509 BPF_FIELD_SIZEOF(struct bpf_cg_run_ctx, retval),
2510 treg, si->src_reg,
2511 offsetof(struct bpf_cg_run_ctx, retval),
2512 si->imm);
2513 *insn++ = BPF_LDX_MEM(BPF_DW, treg, si->dst_reg,
2514 offsetof(struct bpf_sockopt_kern, tmp_reg));
2515 } else {
2516 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, current_task),
2517 si->dst_reg, si->src_reg,
2518 offsetof(struct bpf_sockopt_kern, current_task));
2519 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct task_struct, bpf_ctx),
2520 si->dst_reg, si->dst_reg,
2521 offsetof(struct task_struct, bpf_ctx));
2522 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_cg_run_ctx, retval),
2523 si->dst_reg, si->dst_reg,
2524 offsetof(struct bpf_cg_run_ctx, retval));
2525 }
2526 break;
2527 case offsetof(struct bpf_sockopt, optval):
2528 *insn++ = CG_SOCKOPT_READ_FIELD(optval);
2529 break;
2530 case offsetof(struct bpf_sockopt, optval_end):
2531 *insn++ = CG_SOCKOPT_READ_FIELD(optval_end);
2532 break;
2533 }
2534
2535 return insn - insn_buf;
2536 }
2537
cg_sockopt_get_prologue(struct bpf_insn * insn_buf,bool direct_write,const struct bpf_prog * prog)2538 static int cg_sockopt_get_prologue(struct bpf_insn *insn_buf,
2539 bool direct_write,
2540 const struct bpf_prog *prog)
2541 {
2542 /* Nothing to do for sockopt argument. The data is kzalloc'ated.
2543 */
2544 return 0;
2545 }
2546
2547 const struct bpf_verifier_ops cg_sockopt_verifier_ops = {
2548 .get_func_proto = cg_sockopt_func_proto,
2549 .is_valid_access = cg_sockopt_is_valid_access,
2550 .convert_ctx_access = cg_sockopt_convert_ctx_access,
2551 .gen_prologue = cg_sockopt_get_prologue,
2552 };
2553
2554 const struct bpf_prog_ops cg_sockopt_prog_ops = {
2555 };
2556
2557 /* Common helpers for cgroup hooks. */
2558 const struct bpf_func_proto *
cgroup_common_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)2559 cgroup_common_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
2560 {
2561 switch (func_id) {
2562 case BPF_FUNC_get_local_storage:
2563 return &bpf_get_local_storage_proto;
2564 case BPF_FUNC_get_retval:
2565 switch (prog->expected_attach_type) {
2566 case BPF_CGROUP_INET_INGRESS:
2567 case BPF_CGROUP_INET_EGRESS:
2568 case BPF_CGROUP_SOCK_OPS:
2569 case BPF_CGROUP_UDP4_RECVMSG:
2570 case BPF_CGROUP_UDP6_RECVMSG:
2571 case BPF_CGROUP_UNIX_RECVMSG:
2572 case BPF_CGROUP_INET4_GETPEERNAME:
2573 case BPF_CGROUP_INET6_GETPEERNAME:
2574 case BPF_CGROUP_UNIX_GETPEERNAME:
2575 case BPF_CGROUP_INET4_GETSOCKNAME:
2576 case BPF_CGROUP_INET6_GETSOCKNAME:
2577 case BPF_CGROUP_UNIX_GETSOCKNAME:
2578 return NULL;
2579 default:
2580 return &bpf_get_retval_proto;
2581 }
2582 case BPF_FUNC_set_retval:
2583 switch (prog->expected_attach_type) {
2584 case BPF_CGROUP_INET_INGRESS:
2585 case BPF_CGROUP_INET_EGRESS:
2586 case BPF_CGROUP_SOCK_OPS:
2587 case BPF_CGROUP_UDP4_RECVMSG:
2588 case BPF_CGROUP_UDP6_RECVMSG:
2589 case BPF_CGROUP_UNIX_RECVMSG:
2590 case BPF_CGROUP_INET4_GETPEERNAME:
2591 case BPF_CGROUP_INET6_GETPEERNAME:
2592 case BPF_CGROUP_UNIX_GETPEERNAME:
2593 case BPF_CGROUP_INET4_GETSOCKNAME:
2594 case BPF_CGROUP_INET6_GETSOCKNAME:
2595 case BPF_CGROUP_UNIX_GETSOCKNAME:
2596 return NULL;
2597 default:
2598 return &bpf_set_retval_proto;
2599 }
2600 default:
2601 return NULL;
2602 }
2603 }
2604
2605 /* Common helpers for cgroup hooks with valid process context. */
2606 const struct bpf_func_proto *
cgroup_current_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)2607 cgroup_current_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
2608 {
2609 switch (func_id) {
2610 case BPF_FUNC_get_current_uid_gid:
2611 return &bpf_get_current_uid_gid_proto;
2612 case BPF_FUNC_get_current_comm:
2613 return &bpf_get_current_comm_proto;
2614 #ifdef CONFIG_CGROUP_NET_CLASSID
2615 case BPF_FUNC_get_cgroup_classid:
2616 return &bpf_get_cgroup_classid_curr_proto;
2617 #endif
2618 case BPF_FUNC_current_task_under_cgroup:
2619 return &bpf_current_task_under_cgroup_proto;
2620 default:
2621 return NULL;
2622 }
2623 }
2624