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