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tcp/dccp: fix potential NULL deref in __inet_inherit_port()
[karo-tx-linux.git] / net / ipv4 / inet_hashtables.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              Generic INET transport hashtables
7  *
8  * Authors:     Lotsa people, from code originally in tcp
9  *
10  *      This program is free software; you can redistribute it and/or
11  *      modify it under the terms of the GNU General Public License
12  *      as published by the Free Software Foundation; either version
13  *      2 of the License, or (at your option) any later version.
14  */
15
16 #include <linux/module.h>
17 #include <linux/random.h>
18 #include <linux/sched.h>
19 #include <linux/slab.h>
20 #include <linux/wait.h>
21 #include <linux/vmalloc.h>
22
23 #include <net/inet_connection_sock.h>
24 #include <net/inet_hashtables.h>
25 #include <net/secure_seq.h>
26 #include <net/ip.h>
27
28 static u32 inet_ehashfn(const struct net *net, const __be32 laddr,
29                         const __u16 lport, const __be32 faddr,
30                         const __be16 fport)
31 {
32         static u32 inet_ehash_secret __read_mostly;
33
34         net_get_random_once(&inet_ehash_secret, sizeof(inet_ehash_secret));
35
36         return __inet_ehashfn(laddr, lport, faddr, fport,
37                               inet_ehash_secret + net_hash_mix(net));
38 }
39
40 /* This function handles inet_sock, but also timewait and request sockets
41  * for IPv4/IPv6.
42  */
43 u32 sk_ehashfn(const struct sock *sk)
44 {
45 #if IS_ENABLED(CONFIG_IPV6)
46         if (sk->sk_family == AF_INET6 &&
47             !ipv6_addr_v4mapped(&sk->sk_v6_daddr))
48                 return inet6_ehashfn(sock_net(sk),
49                                      &sk->sk_v6_rcv_saddr, sk->sk_num,
50                                      &sk->sk_v6_daddr, sk->sk_dport);
51 #endif
52         return inet_ehashfn(sock_net(sk),
53                             sk->sk_rcv_saddr, sk->sk_num,
54                             sk->sk_daddr, sk->sk_dport);
55 }
56
57 /*
58  * Allocate and initialize a new local port bind bucket.
59  * The bindhash mutex for snum's hash chain must be held here.
60  */
61 struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
62                                                  struct net *net,
63                                                  struct inet_bind_hashbucket *head,
64                                                  const unsigned short snum)
65 {
66         struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
67
68         if (tb) {
69                 write_pnet(&tb->ib_net, net);
70                 tb->port      = snum;
71                 tb->fastreuse = 0;
72                 tb->fastreuseport = 0;
73                 tb->num_owners = 0;
74                 INIT_HLIST_HEAD(&tb->owners);
75                 hlist_add_head(&tb->node, &head->chain);
76         }
77         return tb;
78 }
79
80 /*
81  * Caller must hold hashbucket lock for this tb with local BH disabled
82  */
83 void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
84 {
85         if (hlist_empty(&tb->owners)) {
86                 __hlist_del(&tb->node);
87                 kmem_cache_free(cachep, tb);
88         }
89 }
90
91 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
92                     const unsigned short snum)
93 {
94         inet_sk(sk)->inet_num = snum;
95         sk_add_bind_node(sk, &tb->owners);
96         tb->num_owners++;
97         inet_csk(sk)->icsk_bind_hash = tb;
98 }
99
100 /*
101  * Get rid of any references to a local port held by the given sock.
102  */
103 static void __inet_put_port(struct sock *sk)
104 {
105         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
106         const int bhash = inet_bhashfn(sock_net(sk), inet_sk(sk)->inet_num,
107                         hashinfo->bhash_size);
108         struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
109         struct inet_bind_bucket *tb;
110
111         spin_lock(&head->lock);
112         tb = inet_csk(sk)->icsk_bind_hash;
113         __sk_del_bind_node(sk);
114         tb->num_owners--;
115         inet_csk(sk)->icsk_bind_hash = NULL;
116         inet_sk(sk)->inet_num = 0;
117         inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
118         spin_unlock(&head->lock);
119 }
120
121 void inet_put_port(struct sock *sk)
122 {
123         local_bh_disable();
124         __inet_put_port(sk);
125         local_bh_enable();
126 }
127 EXPORT_SYMBOL(inet_put_port);
128
129 int __inet_inherit_port(const struct sock *sk, struct sock *child)
130 {
131         struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
132         unsigned short port = inet_sk(child)->inet_num;
133         const int bhash = inet_bhashfn(sock_net(sk), port,
134                         table->bhash_size);
135         struct inet_bind_hashbucket *head = &table->bhash[bhash];
136         struct inet_bind_bucket *tb;
137
138         spin_lock(&head->lock);
139         tb = inet_csk(sk)->icsk_bind_hash;
140         if (unlikely(!tb)) {
141                 spin_unlock(&head->lock);
142                 return -ENOENT;
143         }
144         if (tb->port != port) {
145                 /* NOTE: using tproxy and redirecting skbs to a proxy
146                  * on a different listener port breaks the assumption
147                  * that the listener socket's icsk_bind_hash is the same
148                  * as that of the child socket. We have to look up or
149                  * create a new bind bucket for the child here. */
150                 inet_bind_bucket_for_each(tb, &head->chain) {
151                         if (net_eq(ib_net(tb), sock_net(sk)) &&
152                             tb->port == port)
153                                 break;
154                 }
155                 if (!tb) {
156                         tb = inet_bind_bucket_create(table->bind_bucket_cachep,
157                                                      sock_net(sk), head, port);
158                         if (!tb) {
159                                 spin_unlock(&head->lock);
160                                 return -ENOMEM;
161                         }
162                 }
163         }
164         inet_bind_hash(child, tb, port);
165         spin_unlock(&head->lock);
166
167         return 0;
168 }
169 EXPORT_SYMBOL_GPL(__inet_inherit_port);
170
171 static inline int compute_score(struct sock *sk, struct net *net,
172                                 const unsigned short hnum, const __be32 daddr,
173                                 const int dif)
174 {
175         int score = -1;
176         struct inet_sock *inet = inet_sk(sk);
177
178         if (net_eq(sock_net(sk), net) && inet->inet_num == hnum &&
179                         !ipv6_only_sock(sk)) {
180                 __be32 rcv_saddr = inet->inet_rcv_saddr;
181                 score = sk->sk_family == PF_INET ? 2 : 1;
182                 if (rcv_saddr) {
183                         if (rcv_saddr != daddr)
184                                 return -1;
185                         score += 4;
186                 }
187                 if (sk->sk_bound_dev_if) {
188                         if (sk->sk_bound_dev_if != dif)
189                                 return -1;
190                         score += 4;
191                 }
192                 if (sk->sk_incoming_cpu == raw_smp_processor_id())
193                         score++;
194         }
195         return score;
196 }
197
198 /*
199  * Don't inline this cruft. Here are some nice properties to exploit here. The
200  * BSD API does not allow a listening sock to specify the remote port nor the
201  * remote address for the connection. So always assume those are both
202  * wildcarded during the search since they can never be otherwise.
203  */
204
205
206 struct sock *__inet_lookup_listener(struct net *net,
207                                     struct inet_hashinfo *hashinfo,
208                                     const __be32 saddr, __be16 sport,
209                                     const __be32 daddr, const unsigned short hnum,
210                                     const int dif)
211 {
212         struct sock *sk, *result;
213         struct hlist_nulls_node *node;
214         unsigned int hash = inet_lhashfn(net, hnum);
215         struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
216         int score, hiscore, matches = 0, reuseport = 0;
217         u32 phash = 0;
218
219         rcu_read_lock();
220 begin:
221         result = NULL;
222         hiscore = 0;
223         sk_nulls_for_each_rcu(sk, node, &ilb->head) {
224                 score = compute_score(sk, net, hnum, daddr, dif);
225                 if (score > hiscore) {
226                         result = sk;
227                         hiscore = score;
228                         reuseport = sk->sk_reuseport;
229                         if (reuseport) {
230                                 phash = inet_ehashfn(net, daddr, hnum,
231                                                      saddr, sport);
232                                 matches = 1;
233                         }
234                 } else if (score == hiscore && reuseport) {
235                         matches++;
236                         if (reciprocal_scale(phash, matches) == 0)
237                                 result = sk;
238                         phash = next_pseudo_random32(phash);
239                 }
240         }
241         /*
242          * if the nulls value we got at the end of this lookup is
243          * not the expected one, we must restart lookup.
244          * We probably met an item that was moved to another chain.
245          */
246         if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
247                 goto begin;
248         if (result) {
249                 if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
250                         result = NULL;
251                 else if (unlikely(compute_score(result, net, hnum, daddr,
252                                   dif) < hiscore)) {
253                         sock_put(result);
254                         goto begin;
255                 }
256         }
257         rcu_read_unlock();
258         return result;
259 }
260 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
261
262 /* All sockets share common refcount, but have different destructors */
263 void sock_gen_put(struct sock *sk)
264 {
265         if (!atomic_dec_and_test(&sk->sk_refcnt))
266                 return;
267
268         if (sk->sk_state == TCP_TIME_WAIT)
269                 inet_twsk_free(inet_twsk(sk));
270         else if (sk->sk_state == TCP_NEW_SYN_RECV)
271                 reqsk_free(inet_reqsk(sk));
272         else
273                 sk_free(sk);
274 }
275 EXPORT_SYMBOL_GPL(sock_gen_put);
276
277 void sock_edemux(struct sk_buff *skb)
278 {
279         sock_gen_put(skb->sk);
280 }
281 EXPORT_SYMBOL(sock_edemux);
282
283 struct sock *__inet_lookup_established(struct net *net,
284                                   struct inet_hashinfo *hashinfo,
285                                   const __be32 saddr, const __be16 sport,
286                                   const __be32 daddr, const u16 hnum,
287                                   const int dif)
288 {
289         INET_ADDR_COOKIE(acookie, saddr, daddr);
290         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
291         struct sock *sk;
292         const struct hlist_nulls_node *node;
293         /* Optimize here for direct hit, only listening connections can
294          * have wildcards anyways.
295          */
296         unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
297         unsigned int slot = hash & hashinfo->ehash_mask;
298         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
299
300         rcu_read_lock();
301 begin:
302         sk_nulls_for_each_rcu(sk, node, &head->chain) {
303                 if (sk->sk_hash != hash)
304                         continue;
305                 if (likely(INET_MATCH(sk, net, acookie,
306                                       saddr, daddr, ports, dif))) {
307                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
308                                 goto out;
309                         if (unlikely(!INET_MATCH(sk, net, acookie,
310                                                  saddr, daddr, ports, dif))) {
311                                 sock_gen_put(sk);
312                                 goto begin;
313                         }
314                         goto found;
315                 }
316         }
317         /*
318          * if the nulls value we got at the end of this lookup is
319          * not the expected one, we must restart lookup.
320          * We probably met an item that was moved to another chain.
321          */
322         if (get_nulls_value(node) != slot)
323                 goto begin;
324 out:
325         sk = NULL;
326 found:
327         rcu_read_unlock();
328         return sk;
329 }
330 EXPORT_SYMBOL_GPL(__inet_lookup_established);
331
332 /* called with local bh disabled */
333 static int __inet_check_established(struct inet_timewait_death_row *death_row,
334                                     struct sock *sk, __u16 lport,
335                                     struct inet_timewait_sock **twp)
336 {
337         struct inet_hashinfo *hinfo = death_row->hashinfo;
338         struct inet_sock *inet = inet_sk(sk);
339         __be32 daddr = inet->inet_rcv_saddr;
340         __be32 saddr = inet->inet_daddr;
341         int dif = sk->sk_bound_dev_if;
342         INET_ADDR_COOKIE(acookie, saddr, daddr);
343         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
344         struct net *net = sock_net(sk);
345         unsigned int hash = inet_ehashfn(net, daddr, lport,
346                                          saddr, inet->inet_dport);
347         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
348         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
349         struct sock *sk2;
350         const struct hlist_nulls_node *node;
351         struct inet_timewait_sock *tw = NULL;
352
353         spin_lock(lock);
354
355         sk_nulls_for_each(sk2, node, &head->chain) {
356                 if (sk2->sk_hash != hash)
357                         continue;
358
359                 if (likely(INET_MATCH(sk2, net, acookie,
360                                          saddr, daddr, ports, dif))) {
361                         if (sk2->sk_state == TCP_TIME_WAIT) {
362                                 tw = inet_twsk(sk2);
363                                 if (twsk_unique(sk, sk2, twp))
364                                         break;
365                         }
366                         goto not_unique;
367                 }
368         }
369
370         /* Must record num and sport now. Otherwise we will see
371          * in hash table socket with a funny identity.
372          */
373         inet->inet_num = lport;
374         inet->inet_sport = htons(lport);
375         sk->sk_hash = hash;
376         WARN_ON(!sk_unhashed(sk));
377         __sk_nulls_add_node_rcu(sk, &head->chain);
378         if (tw) {
379                 sk_nulls_del_node_init_rcu((struct sock *)tw);
380                 NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
381         }
382         spin_unlock(lock);
383         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
384
385         if (twp) {
386                 *twp = tw;
387         } else if (tw) {
388                 /* Silly. Should hash-dance instead... */
389                 inet_twsk_deschedule_put(tw);
390         }
391         return 0;
392
393 not_unique:
394         spin_unlock(lock);
395         return -EADDRNOTAVAIL;
396 }
397
398 static u32 inet_sk_port_offset(const struct sock *sk)
399 {
400         const struct inet_sock *inet = inet_sk(sk);
401
402         return secure_ipv4_port_ephemeral(inet->inet_rcv_saddr,
403                                           inet->inet_daddr,
404                                           inet->inet_dport);
405 }
406
407 /* insert a socket into ehash, and eventually remove another one
408  * (The another one can be a SYN_RECV or TIMEWAIT
409  */
410 int inet_ehash_insert(struct sock *sk, struct sock *osk)
411 {
412         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
413         struct hlist_nulls_head *list;
414         struct inet_ehash_bucket *head;
415         spinlock_t *lock;
416         int ret = 0;
417
418         WARN_ON_ONCE(!sk_unhashed(sk));
419
420         sk->sk_hash = sk_ehashfn(sk);
421         head = inet_ehash_bucket(hashinfo, sk->sk_hash);
422         list = &head->chain;
423         lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
424
425         spin_lock(lock);
426         __sk_nulls_add_node_rcu(sk, list);
427         if (osk) {
428                 WARN_ON(sk->sk_hash != osk->sk_hash);
429                 sk_nulls_del_node_init_rcu(osk);
430         }
431         spin_unlock(lock);
432         return ret;
433 }
434
435 void __inet_hash_nolisten(struct sock *sk, struct sock *osk)
436 {
437         inet_ehash_insert(sk, osk);
438         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
439 }
440 EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
441
442 void __inet_hash(struct sock *sk, struct sock *osk)
443 {
444         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
445         struct inet_listen_hashbucket *ilb;
446
447         if (sk->sk_state != TCP_LISTEN)
448                 return __inet_hash_nolisten(sk, osk);
449
450         WARN_ON(!sk_unhashed(sk));
451         ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
452
453         spin_lock(&ilb->lock);
454         __sk_nulls_add_node_rcu(sk, &ilb->head);
455         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
456         spin_unlock(&ilb->lock);
457 }
458 EXPORT_SYMBOL(__inet_hash);
459
460 void inet_hash(struct sock *sk)
461 {
462         if (sk->sk_state != TCP_CLOSE) {
463                 local_bh_disable();
464                 __inet_hash(sk, NULL);
465                 local_bh_enable();
466         }
467 }
468 EXPORT_SYMBOL_GPL(inet_hash);
469
470 void inet_unhash(struct sock *sk)
471 {
472         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
473         spinlock_t *lock;
474         int done;
475
476         if (sk_unhashed(sk))
477                 return;
478
479         if (sk->sk_state == TCP_LISTEN)
480                 lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
481         else
482                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
483
484         spin_lock_bh(lock);
485         done = __sk_nulls_del_node_init_rcu(sk);
486         if (done)
487                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
488         spin_unlock_bh(lock);
489 }
490 EXPORT_SYMBOL_GPL(inet_unhash);
491
492 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
493                 struct sock *sk, u32 port_offset,
494                 int (*check_established)(struct inet_timewait_death_row *,
495                         struct sock *, __u16, struct inet_timewait_sock **))
496 {
497         struct inet_hashinfo *hinfo = death_row->hashinfo;
498         const unsigned short snum = inet_sk(sk)->inet_num;
499         struct inet_bind_hashbucket *head;
500         struct inet_bind_bucket *tb;
501         int ret;
502         struct net *net = sock_net(sk);
503
504         if (!snum) {
505                 int i, remaining, low, high, port;
506                 static u32 hint;
507                 u32 offset = hint + port_offset;
508                 struct inet_timewait_sock *tw = NULL;
509
510                 inet_get_local_port_range(net, &low, &high);
511                 remaining = (high - low) + 1;
512
513                 /* By starting with offset being an even number,
514                  * we tend to leave about 50% of ports for other uses,
515                  * like bind(0).
516                  */
517                 offset &= ~1;
518
519                 local_bh_disable();
520                 for (i = 0; i < remaining; i++) {
521                         port = low + (i + offset) % remaining;
522                         if (inet_is_local_reserved_port(net, port))
523                                 continue;
524                         head = &hinfo->bhash[inet_bhashfn(net, port,
525                                         hinfo->bhash_size)];
526                         spin_lock(&head->lock);
527
528                         /* Does not bother with rcv_saddr checks,
529                          * because the established check is already
530                          * unique enough.
531                          */
532                         inet_bind_bucket_for_each(tb, &head->chain) {
533                                 if (net_eq(ib_net(tb), net) &&
534                                     tb->port == port) {
535                                         if (tb->fastreuse >= 0 ||
536                                             tb->fastreuseport >= 0)
537                                                 goto next_port;
538                                         WARN_ON(hlist_empty(&tb->owners));
539                                         if (!check_established(death_row, sk,
540                                                                 port, &tw))
541                                                 goto ok;
542                                         goto next_port;
543                                 }
544                         }
545
546                         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
547                                         net, head, port);
548                         if (!tb) {
549                                 spin_unlock(&head->lock);
550                                 break;
551                         }
552                         tb->fastreuse = -1;
553                         tb->fastreuseport = -1;
554                         goto ok;
555
556                 next_port:
557                         spin_unlock(&head->lock);
558                 }
559                 local_bh_enable();
560
561                 return -EADDRNOTAVAIL;
562
563 ok:
564                 hint += (i + 2) & ~1;
565
566                 /* Head lock still held and bh's disabled */
567                 inet_bind_hash(sk, tb, port);
568                 if (sk_unhashed(sk)) {
569                         inet_sk(sk)->inet_sport = htons(port);
570                         __inet_hash_nolisten(sk, (struct sock *)tw);
571                 }
572                 if (tw)
573                         inet_twsk_bind_unhash(tw, hinfo);
574                 spin_unlock(&head->lock);
575
576                 if (tw)
577                         inet_twsk_deschedule_put(tw);
578
579                 ret = 0;
580                 goto out;
581         }
582
583         head = &hinfo->bhash[inet_bhashfn(net, snum, hinfo->bhash_size)];
584         tb  = inet_csk(sk)->icsk_bind_hash;
585         spin_lock_bh(&head->lock);
586         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
587                 __inet_hash_nolisten(sk, NULL);
588                 spin_unlock_bh(&head->lock);
589                 return 0;
590         } else {
591                 spin_unlock(&head->lock);
592                 /* No definite answer... Walk to established hash table */
593                 ret = check_established(death_row, sk, snum, NULL);
594 out:
595                 local_bh_enable();
596                 return ret;
597         }
598 }
599
600 /*
601  * Bind a port for a connect operation and hash it.
602  */
603 int inet_hash_connect(struct inet_timewait_death_row *death_row,
604                       struct sock *sk)
605 {
606         u32 port_offset = 0;
607
608         if (!inet_sk(sk)->inet_num)
609                 port_offset = inet_sk_port_offset(sk);
610         return __inet_hash_connect(death_row, sk, port_offset,
611                                    __inet_check_established);
612 }
613 EXPORT_SYMBOL_GPL(inet_hash_connect);
614
615 void inet_hashinfo_init(struct inet_hashinfo *h)
616 {
617         int i;
618
619         for (i = 0; i < INET_LHTABLE_SIZE; i++) {
620                 spin_lock_init(&h->listening_hash[i].lock);
621                 INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].head,
622                                       i + LISTENING_NULLS_BASE);
623                 }
624 }
625 EXPORT_SYMBOL_GPL(inet_hashinfo_init);
626
627 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
628 {
629         unsigned int locksz = sizeof(spinlock_t);
630         unsigned int i, nblocks = 1;
631
632         if (locksz != 0) {
633                 /* allocate 2 cache lines or at least one spinlock per cpu */
634                 nblocks = max(2U * L1_CACHE_BYTES / locksz, 1U);
635                 nblocks = roundup_pow_of_two(nblocks * num_possible_cpus());
636
637                 /* no more locks than number of hash buckets */
638                 nblocks = min(nblocks, hashinfo->ehash_mask + 1);
639
640                 hashinfo->ehash_locks = kmalloc_array(nblocks, locksz,
641                                                       GFP_KERNEL | __GFP_NOWARN);
642                 if (!hashinfo->ehash_locks)
643                         hashinfo->ehash_locks = vmalloc(nblocks * locksz);
644
645                 if (!hashinfo->ehash_locks)
646                         return -ENOMEM;
647
648                 for (i = 0; i < nblocks; i++)
649                         spin_lock_init(&hashinfo->ehash_locks[i]);
650         }
651         hashinfo->ehash_locks_mask = nblocks - 1;
652         return 0;
653 }
654 EXPORT_SYMBOL_GPL(inet_ehash_locks_alloc);