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Linux/net/netfilter/nfnetlink_log.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * This is a module which is used for logging packets to userspace via
  4  * nfetlink.
  5  *
  6  * (C) 2005 by Harald Welte <laforge@netfilter.org>
  7  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
  8  *
  9  * Based on the old ipv4-only ipt_ULOG.c:
 10  * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
 11  */
 12 
 13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 14 
 15 #include <linux/module.h>
 16 #include <linux/skbuff.h>
 17 #include <linux/if_arp.h>
 18 #include <linux/init.h>
 19 #include <linux/ip.h>
 20 #include <linux/ipv6.h>
 21 #include <linux/netdevice.h>
 22 #include <linux/netfilter.h>
 23 #include <linux/netfilter_bridge.h>
 24 #include <net/netlink.h>
 25 #include <linux/netfilter/nfnetlink.h>
 26 #include <linux/netfilter/nfnetlink_log.h>
 27 #include <linux/netfilter/nf_conntrack_common.h>
 28 #include <linux/spinlock.h>
 29 #include <linux/sysctl.h>
 30 #include <linux/proc_fs.h>
 31 #include <linux/security.h>
 32 #include <linux/list.h>
 33 #include <linux/slab.h>
 34 #include <net/sock.h>
 35 #include <net/netfilter/nf_log.h>
 36 #include <net/netns/generic.h>
 37 
 38 #include <linux/atomic.h>
 39 #include <linux/refcount.h>
 40 
 41 
 42 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 43 #include "../bridge/br_private.h"
 44 #endif
 45 
 46 #define NFULNL_COPY_DISABLED    0xff
 47 #define NFULNL_NLBUFSIZ_DEFAULT NLMSG_GOODSIZE
 48 #define NFULNL_TIMEOUT_DEFAULT  100     /* every second */
 49 #define NFULNL_QTHRESH_DEFAULT  100     /* 100 packets */
 50 /* max packet size is limited by 16-bit struct nfattr nfa_len field */
 51 #define NFULNL_COPY_RANGE_MAX   (0xFFFF - NLA_HDRLEN)
 52 
 53 #define PRINTR(x, args...)      do { if (net_ratelimit()) \
 54                                      printk(x, ## args); } while (0);
 55 
 56 struct nfulnl_instance {
 57         struct hlist_node hlist;        /* global list of instances */
 58         spinlock_t lock;
 59         refcount_t use;                 /* use count */
 60 
 61         unsigned int qlen;              /* number of nlmsgs in skb */
 62         struct sk_buff *skb;            /* pre-allocatd skb */
 63         struct timer_list timer;
 64         struct net *net;
 65         struct user_namespace *peer_user_ns;    /* User namespace of the peer process */
 66         u32 peer_portid;                /* PORTID of the peer process */
 67 
 68         /* configurable parameters */
 69         unsigned int flushtimeout;      /* timeout until queue flush */
 70         unsigned int nlbufsiz;          /* netlink buffer allocation size */
 71         unsigned int qthreshold;        /* threshold of the queue */
 72         u_int32_t copy_range;
 73         u_int32_t seq;                  /* instance-local sequential counter */
 74         u_int16_t group_num;            /* number of this queue */
 75         u_int16_t flags;
 76         u_int8_t copy_mode;
 77         struct rcu_head rcu;
 78 };
 79 
 80 #define INSTANCE_BUCKETS        16
 81 
 82 static unsigned int nfnl_log_net_id __read_mostly;
 83 
 84 struct nfnl_log_net {
 85         spinlock_t instances_lock;
 86         struct hlist_head instance_table[INSTANCE_BUCKETS];
 87         atomic_t global_seq;
 88 };
 89 
 90 static struct nfnl_log_net *nfnl_log_pernet(struct net *net)
 91 {
 92         return net_generic(net, nfnl_log_net_id);
 93 }
 94 
 95 static inline u_int8_t instance_hashfn(u_int16_t group_num)
 96 {
 97         return ((group_num & 0xff) % INSTANCE_BUCKETS);
 98 }
 99 
100 static struct nfulnl_instance *
101 __instance_lookup(struct nfnl_log_net *log, u_int16_t group_num)
102 {
103         struct hlist_head *head;
104         struct nfulnl_instance *inst;
105 
106         head = &log->instance_table[instance_hashfn(group_num)];
107         hlist_for_each_entry_rcu(inst, head, hlist) {
108                 if (inst->group_num == group_num)
109                         return inst;
110         }
111         return NULL;
112 }
113 
114 static inline void
115 instance_get(struct nfulnl_instance *inst)
116 {
117         refcount_inc(&inst->use);
118 }
119 
120 static struct nfulnl_instance *
121 instance_lookup_get(struct nfnl_log_net *log, u_int16_t group_num)
122 {
123         struct nfulnl_instance *inst;
124 
125         rcu_read_lock_bh();
126         inst = __instance_lookup(log, group_num);
127         if (inst && !refcount_inc_not_zero(&inst->use))
128                 inst = NULL;
129         rcu_read_unlock_bh();
130 
131         return inst;
132 }
133 
134 static void nfulnl_instance_free_rcu(struct rcu_head *head)
135 {
136         struct nfulnl_instance *inst =
137                 container_of(head, struct nfulnl_instance, rcu);
138 
139         put_net(inst->net);
140         kfree(inst);
141         module_put(THIS_MODULE);
142 }
143 
144 static void
145 instance_put(struct nfulnl_instance *inst)
146 {
147         if (inst && refcount_dec_and_test(&inst->use))
148                 call_rcu(&inst->rcu, nfulnl_instance_free_rcu);
149 }
150 
151 static void nfulnl_timer(struct timer_list *t);
152 
153 static struct nfulnl_instance *
154 instance_create(struct net *net, u_int16_t group_num,
155                 u32 portid, struct user_namespace *user_ns)
156 {
157         struct nfulnl_instance *inst;
158         struct nfnl_log_net *log = nfnl_log_pernet(net);
159         int err;
160 
161         spin_lock_bh(&log->instances_lock);
162         if (__instance_lookup(log, group_num)) {
163                 err = -EEXIST;
164                 goto out_unlock;
165         }
166 
167         inst = kzalloc(sizeof(*inst), GFP_ATOMIC);
168         if (!inst) {
169                 err = -ENOMEM;
170                 goto out_unlock;
171         }
172 
173         if (!try_module_get(THIS_MODULE)) {
174                 kfree(inst);
175                 err = -EAGAIN;
176                 goto out_unlock;
177         }
178 
179         INIT_HLIST_NODE(&inst->hlist);
180         spin_lock_init(&inst->lock);
181         /* needs to be two, since we _put() after creation */
182         refcount_set(&inst->use, 2);
183 
184         timer_setup(&inst->timer, nfulnl_timer, 0);
185 
186         inst->net = get_net(net);
187         inst->peer_user_ns = user_ns;
188         inst->peer_portid = portid;
189         inst->group_num = group_num;
190 
191         inst->qthreshold        = NFULNL_QTHRESH_DEFAULT;
192         inst->flushtimeout      = NFULNL_TIMEOUT_DEFAULT;
193         inst->nlbufsiz          = NFULNL_NLBUFSIZ_DEFAULT;
194         inst->copy_mode         = NFULNL_COPY_PACKET;
195         inst->copy_range        = NFULNL_COPY_RANGE_MAX;
196 
197         hlist_add_head_rcu(&inst->hlist,
198                        &log->instance_table[instance_hashfn(group_num)]);
199 
200 
201         spin_unlock_bh(&log->instances_lock);
202 
203         return inst;
204 
205 out_unlock:
206         spin_unlock_bh(&log->instances_lock);
207         return ERR_PTR(err);
208 }
209 
210 static void __nfulnl_flush(struct nfulnl_instance *inst);
211 
212 /* called with BH disabled */
213 static void
214 __instance_destroy(struct nfulnl_instance *inst)
215 {
216         /* first pull it out of the global list */
217         hlist_del_rcu(&inst->hlist);
218 
219         /* then flush all pending packets from skb */
220 
221         spin_lock(&inst->lock);
222 
223         /* lockless readers wont be able to use us */
224         inst->copy_mode = NFULNL_COPY_DISABLED;
225 
226         if (inst->skb)
227                 __nfulnl_flush(inst);
228         spin_unlock(&inst->lock);
229 
230         /* and finally put the refcount */
231         instance_put(inst);
232 }
233 
234 static inline void
235 instance_destroy(struct nfnl_log_net *log,
236                  struct nfulnl_instance *inst)
237 {
238         spin_lock_bh(&log->instances_lock);
239         __instance_destroy(inst);
240         spin_unlock_bh(&log->instances_lock);
241 }
242 
243 static int
244 nfulnl_set_mode(struct nfulnl_instance *inst, u_int8_t mode,
245                   unsigned int range)
246 {
247         int status = 0;
248 
249         spin_lock_bh(&inst->lock);
250 
251         switch (mode) {
252         case NFULNL_COPY_NONE:
253         case NFULNL_COPY_META:
254                 inst->copy_mode = mode;
255                 inst->copy_range = 0;
256                 break;
257 
258         case NFULNL_COPY_PACKET:
259                 inst->copy_mode = mode;
260                 if (range == 0)
261                         range = NFULNL_COPY_RANGE_MAX;
262                 inst->copy_range = min_t(unsigned int,
263                                          range, NFULNL_COPY_RANGE_MAX);
264                 break;
265 
266         default:
267                 status = -EINVAL;
268                 break;
269         }
270 
271         spin_unlock_bh(&inst->lock);
272 
273         return status;
274 }
275 
276 static int
277 nfulnl_set_nlbufsiz(struct nfulnl_instance *inst, u_int32_t nlbufsiz)
278 {
279         int status;
280 
281         spin_lock_bh(&inst->lock);
282         if (nlbufsiz < NFULNL_NLBUFSIZ_DEFAULT)
283                 status = -ERANGE;
284         else if (nlbufsiz > 131072)
285                 status = -ERANGE;
286         else {
287                 inst->nlbufsiz = nlbufsiz;
288                 status = 0;
289         }
290         spin_unlock_bh(&inst->lock);
291 
292         return status;
293 }
294 
295 static void
296 nfulnl_set_timeout(struct nfulnl_instance *inst, u_int32_t timeout)
297 {
298         spin_lock_bh(&inst->lock);
299         inst->flushtimeout = timeout;
300         spin_unlock_bh(&inst->lock);
301 }
302 
303 static void
304 nfulnl_set_qthresh(struct nfulnl_instance *inst, u_int32_t qthresh)
305 {
306         spin_lock_bh(&inst->lock);
307         inst->qthreshold = qthresh;
308         spin_unlock_bh(&inst->lock);
309 }
310 
311 static int
312 nfulnl_set_flags(struct nfulnl_instance *inst, u_int16_t flags)
313 {
314         spin_lock_bh(&inst->lock);
315         inst->flags = flags;
316         spin_unlock_bh(&inst->lock);
317 
318         return 0;
319 }
320 
321 static struct sk_buff *
322 nfulnl_alloc_skb(struct net *net, u32 peer_portid, unsigned int inst_size,
323                  unsigned int pkt_size)
324 {
325         struct sk_buff *skb;
326         unsigned int n;
327 
328         /* alloc skb which should be big enough for a whole multipart
329          * message.  WARNING: has to be <= 128k due to slab restrictions */
330 
331         n = max(inst_size, pkt_size);
332         skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN);
333         if (!skb) {
334                 if (n > pkt_size) {
335                         /* try to allocate only as much as we need for current
336                          * packet */
337 
338                         skb = alloc_skb(pkt_size, GFP_ATOMIC);
339                 }
340         }
341 
342         return skb;
343 }
344 
345 static void
346 __nfulnl_send(struct nfulnl_instance *inst)
347 {
348         if (inst->qlen > 1) {
349                 struct nlmsghdr *nlh = nlmsg_put(inst->skb, 0, 0,
350                                                  NLMSG_DONE,
351                                                  sizeof(struct nfgenmsg),
352                                                  0);
353                 if (WARN_ONCE(!nlh, "bad nlskb size: %u, tailroom %d\n",
354                               inst->skb->len, skb_tailroom(inst->skb))) {
355                         kfree_skb(inst->skb);
356                         goto out;
357                 }
358         }
359         nfnetlink_unicast(inst->skb, inst->net, inst->peer_portid,
360                           MSG_DONTWAIT);
361 out:
362         inst->qlen = 0;
363         inst->skb = NULL;
364 }
365 
366 static void
367 __nfulnl_flush(struct nfulnl_instance *inst)
368 {
369         /* timer holds a reference */
370         if (del_timer(&inst->timer))
371                 instance_put(inst);
372         if (inst->skb)
373                 __nfulnl_send(inst);
374 }
375 
376 static void
377 nfulnl_timer(struct timer_list *t)
378 {
379         struct nfulnl_instance *inst = from_timer(inst, t, timer);
380 
381         spin_lock_bh(&inst->lock);
382         if (inst->skb)
383                 __nfulnl_send(inst);
384         spin_unlock_bh(&inst->lock);
385         instance_put(inst);
386 }
387 
388 static u32 nfulnl_get_bridge_size(const struct sk_buff *skb)
389 {
390         u32 size = 0;
391 
392         if (!skb_mac_header_was_set(skb))
393                 return 0;
394 
395         if (skb_vlan_tag_present(skb)) {
396                 size += nla_total_size(0); /* nested */
397                 size += nla_total_size(sizeof(u16)); /* id */
398                 size += nla_total_size(sizeof(u16)); /* tag */
399         }
400 
401         if (skb->network_header > skb->mac_header)
402                 size += nla_total_size(skb->network_header - skb->mac_header);
403 
404         return size;
405 }
406 
407 static int nfulnl_put_bridge(struct nfulnl_instance *inst, const struct sk_buff *skb)
408 {
409         if (!skb_mac_header_was_set(skb))
410                 return 0;
411 
412         if (skb_vlan_tag_present(skb)) {
413                 struct nlattr *nest;
414 
415                 nest = nla_nest_start(inst->skb, NFULA_VLAN);
416                 if (!nest)
417                         goto nla_put_failure;
418 
419                 if (nla_put_be16(inst->skb, NFULA_VLAN_TCI, htons(skb->vlan_tci)) ||
420                     nla_put_be16(inst->skb, NFULA_VLAN_PROTO, skb->vlan_proto))
421                         goto nla_put_failure;
422 
423                 nla_nest_end(inst->skb, nest);
424         }
425 
426         if (skb->mac_header < skb->network_header) {
427                 int len = (int)(skb->network_header - skb->mac_header);
428 
429                 if (nla_put(inst->skb, NFULA_L2HDR, len, skb_mac_header(skb)))
430                         goto nla_put_failure;
431         }
432 
433         return 0;
434 
435 nla_put_failure:
436         return -1;
437 }
438 
439 /* This is an inline function, we don't really care about a long
440  * list of arguments */
441 static inline int
442 __build_packet_message(struct nfnl_log_net *log,
443                         struct nfulnl_instance *inst,
444                         const struct sk_buff *skb,
445                         unsigned int data_len,
446                         u_int8_t pf,
447                         unsigned int hooknum,
448                         const struct net_device *indev,
449                         const struct net_device *outdev,
450                         const char *prefix, unsigned int plen,
451                         const struct nfnl_ct_hook *nfnl_ct,
452                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
453 {
454         struct nfulnl_msg_packet_hdr pmsg;
455         struct nlmsghdr *nlh;
456         struct nfgenmsg *nfmsg;
457         sk_buff_data_t old_tail = inst->skb->tail;
458         struct sock *sk;
459         const unsigned char *hwhdrp;
460 
461         nlh = nlmsg_put(inst->skb, 0, 0,
462                         nfnl_msg_type(NFNL_SUBSYS_ULOG, NFULNL_MSG_PACKET),
463                         sizeof(struct nfgenmsg), 0);
464         if (!nlh)
465                 return -1;
466         nfmsg = nlmsg_data(nlh);
467         nfmsg->nfgen_family = pf;
468         nfmsg->version = NFNETLINK_V0;
469         nfmsg->res_id = htons(inst->group_num);
470 
471         memset(&pmsg, 0, sizeof(pmsg));
472         pmsg.hw_protocol        = skb->protocol;
473         pmsg.hook               = hooknum;
474 
475         if (nla_put(inst->skb, NFULA_PACKET_HDR, sizeof(pmsg), &pmsg))
476                 goto nla_put_failure;
477 
478         if (prefix &&
479             nla_put(inst->skb, NFULA_PREFIX, plen, prefix))
480                 goto nla_put_failure;
481 
482         if (indev) {
483 #if !IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
484                 if (nla_put_be32(inst->skb, NFULA_IFINDEX_INDEV,
485                                  htonl(indev->ifindex)))
486                         goto nla_put_failure;
487 #else
488                 if (pf == PF_BRIDGE) {
489                         /* Case 1: outdev is physical input device, we need to
490                          * look for bridge group (when called from
491                          * netfilter_bridge) */
492                         if (nla_put_be32(inst->skb, NFULA_IFINDEX_PHYSINDEV,
493                                          htonl(indev->ifindex)) ||
494                         /* this is the bridge group "brX" */
495                         /* rcu_read_lock()ed by nf_hook_thresh or
496                          * nf_log_packet.
497                          */
498                             nla_put_be32(inst->skb, NFULA_IFINDEX_INDEV,
499                                          htonl(br_port_get_rcu(indev)->br->dev->ifindex)))
500                                 goto nla_put_failure;
501                 } else {
502                         struct net_device *physindev;
503 
504                         /* Case 2: indev is bridge group, we need to look for
505                          * physical device (when called from ipv4) */
506                         if (nla_put_be32(inst->skb, NFULA_IFINDEX_INDEV,
507                                          htonl(indev->ifindex)))
508                                 goto nla_put_failure;
509 
510                         physindev = nf_bridge_get_physindev(skb);
511                         if (physindev &&
512                             nla_put_be32(inst->skb, NFULA_IFINDEX_PHYSINDEV,
513                                          htonl(physindev->ifindex)))
514                                 goto nla_put_failure;
515                 }
516 #endif
517         }
518 
519         if (outdev) {
520 #if !IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
521                 if (nla_put_be32(inst->skb, NFULA_IFINDEX_OUTDEV,
522                                  htonl(outdev->ifindex)))
523                         goto nla_put_failure;
524 #else
525                 if (pf == PF_BRIDGE) {
526                         /* Case 1: outdev is physical output device, we need to
527                          * look for bridge group (when called from
528                          * netfilter_bridge) */
529                         if (nla_put_be32(inst->skb, NFULA_IFINDEX_PHYSOUTDEV,
530                                          htonl(outdev->ifindex)) ||
531                         /* this is the bridge group "brX" */
532                         /* rcu_read_lock()ed by nf_hook_thresh or
533                          * nf_log_packet.
534                          */
535                             nla_put_be32(inst->skb, NFULA_IFINDEX_OUTDEV,
536                                          htonl(br_port_get_rcu(outdev)->br->dev->ifindex)))
537                                 goto nla_put_failure;
538                 } else {
539                         struct net_device *physoutdev;
540 
541                         /* Case 2: indev is a bridge group, we need to look
542                          * for physical device (when called from ipv4) */
543                         if (nla_put_be32(inst->skb, NFULA_IFINDEX_OUTDEV,
544                                          htonl(outdev->ifindex)))
545                                 goto nla_put_failure;
546 
547                         physoutdev = nf_bridge_get_physoutdev(skb);
548                         if (physoutdev &&
549                             nla_put_be32(inst->skb, NFULA_IFINDEX_PHYSOUTDEV,
550                                          htonl(physoutdev->ifindex)))
551                                 goto nla_put_failure;
552                 }
553 #endif
554         }
555 
556         if (skb->mark &&
557             nla_put_be32(inst->skb, NFULA_MARK, htonl(skb->mark)))
558                 goto nla_put_failure;
559 
560         if (indev && skb->dev &&
561             skb->mac_header != skb->network_header) {
562                 struct nfulnl_msg_packet_hw phw;
563                 int len;
564 
565                 memset(&phw, 0, sizeof(phw));
566                 len = dev_parse_header(skb, phw.hw_addr);
567                 if (len > 0) {
568                         phw.hw_addrlen = htons(len);
569                         if (nla_put(inst->skb, NFULA_HWADDR, sizeof(phw), &phw))
570                                 goto nla_put_failure;
571                 }
572         }
573 
574         if (indev && skb_mac_header_was_set(skb)) {
575                 if (nla_put_be16(inst->skb, NFULA_HWTYPE, htons(skb->dev->type)) ||
576                     nla_put_be16(inst->skb, NFULA_HWLEN,
577                                  htons(skb->dev->hard_header_len)))
578                         goto nla_put_failure;
579 
580                 hwhdrp = skb_mac_header(skb);
581 
582                 if (skb->dev->type == ARPHRD_SIT)
583                         hwhdrp -= ETH_HLEN;
584 
585                 if (hwhdrp >= skb->head &&
586                     nla_put(inst->skb, NFULA_HWHEADER,
587                             skb->dev->hard_header_len, hwhdrp))
588                         goto nla_put_failure;
589         }
590 
591         if (hooknum <= NF_INET_FORWARD && skb->tstamp) {
592                 struct nfulnl_msg_packet_timestamp ts;
593                 struct timespec64 kts = ktime_to_timespec64(skb->tstamp);
594                 ts.sec = cpu_to_be64(kts.tv_sec);
595                 ts.usec = cpu_to_be64(kts.tv_nsec / NSEC_PER_USEC);
596 
597                 if (nla_put(inst->skb, NFULA_TIMESTAMP, sizeof(ts), &ts))
598                         goto nla_put_failure;
599         }
600 
601         /* UID */
602         sk = skb->sk;
603         if (sk && sk_fullsock(sk)) {
604                 read_lock_bh(&sk->sk_callback_lock);
605                 if (sk->sk_socket && sk->sk_socket->file) {
606                         struct file *file = sk->sk_socket->file;
607                         const struct cred *cred = file->f_cred;
608                         struct user_namespace *user_ns = inst->peer_user_ns;
609                         __be32 uid = htonl(from_kuid_munged(user_ns, cred->fsuid));
610                         __be32 gid = htonl(from_kgid_munged(user_ns, cred->fsgid));
611                         read_unlock_bh(&sk->sk_callback_lock);
612                         if (nla_put_be32(inst->skb, NFULA_UID, uid) ||
613                             nla_put_be32(inst->skb, NFULA_GID, gid))
614                                 goto nla_put_failure;
615                 } else
616                         read_unlock_bh(&sk->sk_callback_lock);
617         }
618 
619         /* local sequence number */
620         if ((inst->flags & NFULNL_CFG_F_SEQ) &&
621             nla_put_be32(inst->skb, NFULA_SEQ, htonl(inst->seq++)))
622                 goto nla_put_failure;
623 
624         /* global sequence number */
625         if ((inst->flags & NFULNL_CFG_F_SEQ_GLOBAL) &&
626             nla_put_be32(inst->skb, NFULA_SEQ_GLOBAL,
627                          htonl(atomic_inc_return(&log->global_seq))))
628                 goto nla_put_failure;
629 
630         if (ct && nfnl_ct->build(inst->skb, ct, ctinfo,
631                                  NFULA_CT, NFULA_CT_INFO) < 0)
632                 goto nla_put_failure;
633 
634         if ((pf == NFPROTO_NETDEV || pf == NFPROTO_BRIDGE) &&
635             nfulnl_put_bridge(inst, skb) < 0)
636                 goto nla_put_failure;
637 
638         if (data_len) {
639                 struct nlattr *nla;
640                 int size = nla_attr_size(data_len);
641 
642                 if (skb_tailroom(inst->skb) < nla_total_size(data_len))
643                         goto nla_put_failure;
644 
645                 nla = skb_put(inst->skb, nla_total_size(data_len));
646                 nla->nla_type = NFULA_PAYLOAD;
647                 nla->nla_len = size;
648 
649                 if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
650                         BUG();
651         }
652 
653         nlh->nlmsg_len = inst->skb->tail - old_tail;
654         return 0;
655 
656 nla_put_failure:
657         PRINTR(KERN_ERR "nfnetlink_log: error creating log nlmsg\n");
658         return -1;
659 }
660 
661 static const struct nf_loginfo default_loginfo = {
662         .type =         NF_LOG_TYPE_ULOG,
663         .u = {
664                 .ulog = {
665                         .copy_len       = 0xffff,
666                         .group          = 0,
667                         .qthreshold     = 1,
668                 },
669         },
670 };
671 
672 /* log handler for internal netfilter logging api */
673 static void
674 nfulnl_log_packet(struct net *net,
675                   u_int8_t pf,
676                   unsigned int hooknum,
677                   const struct sk_buff *skb,
678                   const struct net_device *in,
679                   const struct net_device *out,
680                   const struct nf_loginfo *li_user,
681                   const char *prefix)
682 {
683         size_t size;
684         unsigned int data_len;
685         struct nfulnl_instance *inst;
686         const struct nf_loginfo *li;
687         unsigned int qthreshold;
688         unsigned int plen = 0;
689         struct nfnl_log_net *log = nfnl_log_pernet(net);
690         const struct nfnl_ct_hook *nfnl_ct = NULL;
691         struct nf_conn *ct = NULL;
692         enum ip_conntrack_info uninitialized_var(ctinfo);
693 
694         if (li_user && li_user->type == NF_LOG_TYPE_ULOG)
695                 li = li_user;
696         else
697                 li = &default_loginfo;
698 
699         inst = instance_lookup_get(log, li->u.ulog.group);
700         if (!inst)
701                 return;
702 
703         if (prefix)
704                 plen = strlen(prefix) + 1;
705 
706         /* FIXME: do we want to make the size calculation conditional based on
707          * what is actually present?  way more branches and checks, but more
708          * memory efficient... */
709         size = nlmsg_total_size(sizeof(struct nfgenmsg))
710                 + nla_total_size(sizeof(struct nfulnl_msg_packet_hdr))
711                 + nla_total_size(sizeof(u_int32_t))     /* ifindex */
712                 + nla_total_size(sizeof(u_int32_t))     /* ifindex */
713 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
714                 + nla_total_size(sizeof(u_int32_t))     /* ifindex */
715                 + nla_total_size(sizeof(u_int32_t))     /* ifindex */
716 #endif
717                 + nla_total_size(sizeof(u_int32_t))     /* mark */
718                 + nla_total_size(sizeof(u_int32_t))     /* uid */
719                 + nla_total_size(sizeof(u_int32_t))     /* gid */
720                 + nla_total_size(plen)                  /* prefix */
721                 + nla_total_size(sizeof(struct nfulnl_msg_packet_hw))
722                 + nla_total_size(sizeof(struct nfulnl_msg_packet_timestamp))
723                 + nla_total_size(sizeof(struct nfgenmsg));      /* NLMSG_DONE */
724 
725         if (in && skb_mac_header_was_set(skb)) {
726                 size += nla_total_size(skb->dev->hard_header_len)
727                         + nla_total_size(sizeof(u_int16_t))     /* hwtype */
728                         + nla_total_size(sizeof(u_int16_t));    /* hwlen */
729         }
730 
731         spin_lock_bh(&inst->lock);
732 
733         if (inst->flags & NFULNL_CFG_F_SEQ)
734                 size += nla_total_size(sizeof(u_int32_t));
735         if (inst->flags & NFULNL_CFG_F_SEQ_GLOBAL)
736                 size += nla_total_size(sizeof(u_int32_t));
737         if (inst->flags & NFULNL_CFG_F_CONNTRACK) {
738                 nfnl_ct = rcu_dereference(nfnl_ct_hook);
739                 if (nfnl_ct != NULL) {
740                         ct = nfnl_ct->get_ct(skb, &ctinfo);
741                         if (ct != NULL)
742                                 size += nfnl_ct->build_size(ct);
743                 }
744         }
745         if (pf == NFPROTO_NETDEV || pf == NFPROTO_BRIDGE)
746                 size += nfulnl_get_bridge_size(skb);
747 
748         qthreshold = inst->qthreshold;
749         /* per-rule qthreshold overrides per-instance */
750         if (li->u.ulog.qthreshold)
751                 if (qthreshold > li->u.ulog.qthreshold)
752                         qthreshold = li->u.ulog.qthreshold;
753 
754 
755         switch (inst->copy_mode) {
756         case NFULNL_COPY_META:
757         case NFULNL_COPY_NONE:
758                 data_len = 0;
759                 break;
760 
761         case NFULNL_COPY_PACKET:
762                 data_len = inst->copy_range;
763                 if ((li->u.ulog.flags & NF_LOG_F_COPY_LEN) &&
764                     (li->u.ulog.copy_len < data_len))
765                         data_len = li->u.ulog.copy_len;
766 
767                 if (data_len > skb->len)
768                         data_len = skb->len;
769 
770                 size += nla_total_size(data_len);
771                 break;
772 
773         case NFULNL_COPY_DISABLED:
774         default:
775                 goto unlock_and_release;
776         }
777 
778         if (inst->skb && size > skb_tailroom(inst->skb)) {
779                 /* either the queue len is too high or we don't have
780                  * enough room in the skb left. flush to userspace. */
781                 __nfulnl_flush(inst);
782         }
783 
784         if (!inst->skb) {
785                 inst->skb = nfulnl_alloc_skb(net, inst->peer_portid,
786                                              inst->nlbufsiz, size);
787                 if (!inst->skb)
788                         goto alloc_failure;
789         }
790 
791         inst->qlen++;
792 
793         __build_packet_message(log, inst, skb, data_len, pf,
794                                 hooknum, in, out, prefix, plen,
795                                 nfnl_ct, ct, ctinfo);
796 
797         if (inst->qlen >= qthreshold)
798                 __nfulnl_flush(inst);
799         /* timer_pending always called within inst->lock, so there
800          * is no chance of a race here */
801         else if (!timer_pending(&inst->timer)) {
802                 instance_get(inst);
803                 inst->timer.expires = jiffies + (inst->flushtimeout*HZ/100);
804                 add_timer(&inst->timer);
805         }
806 
807 unlock_and_release:
808         spin_unlock_bh(&inst->lock);
809         instance_put(inst);
810         return;
811 
812 alloc_failure:
813         /* FIXME: statistics */
814         goto unlock_and_release;
815 }
816 
817 static int
818 nfulnl_rcv_nl_event(struct notifier_block *this,
819                    unsigned long event, void *ptr)
820 {
821         struct netlink_notify *n = ptr;
822         struct nfnl_log_net *log = nfnl_log_pernet(n->net);
823 
824         if (event == NETLINK_URELEASE && n->protocol == NETLINK_NETFILTER) {
825                 int i;
826 
827                 /* destroy all instances for this portid */
828                 spin_lock_bh(&log->instances_lock);
829                 for  (i = 0; i < INSTANCE_BUCKETS; i++) {
830                         struct hlist_node *t2;
831                         struct nfulnl_instance *inst;
832                         struct hlist_head *head = &log->instance_table[i];
833 
834                         hlist_for_each_entry_safe(inst, t2, head, hlist) {
835                                 if (n->portid == inst->peer_portid)
836                                         __instance_destroy(inst);
837                         }
838                 }
839                 spin_unlock_bh(&log->instances_lock);
840         }
841         return NOTIFY_DONE;
842 }
843 
844 static struct notifier_block nfulnl_rtnl_notifier = {
845         .notifier_call  = nfulnl_rcv_nl_event,
846 };
847 
848 static int nfulnl_recv_unsupp(struct net *net, struct sock *ctnl,
849                               struct sk_buff *skb, const struct nlmsghdr *nlh,
850                               const struct nlattr * const nfqa[],
851                               struct netlink_ext_ack *extack)
852 {
853         return -ENOTSUPP;
854 }
855 
856 static struct nf_logger nfulnl_logger __read_mostly = {
857         .name   = "nfnetlink_log",
858         .type   = NF_LOG_TYPE_ULOG,
859         .logfn  = nfulnl_log_packet,
860         .me     = THIS_MODULE,
861 };
862 
863 static const struct nla_policy nfula_cfg_policy[NFULA_CFG_MAX+1] = {
864         [NFULA_CFG_CMD]         = { .len = sizeof(struct nfulnl_msg_config_cmd) },
865         [NFULA_CFG_MODE]        = { .len = sizeof(struct nfulnl_msg_config_mode) },
866         [NFULA_CFG_TIMEOUT]     = { .type = NLA_U32 },
867         [NFULA_CFG_QTHRESH]     = { .type = NLA_U32 },
868         [NFULA_CFG_NLBUFSIZ]    = { .type = NLA_U32 },
869         [NFULA_CFG_FLAGS]       = { .type = NLA_U16 },
870 };
871 
872 static int nfulnl_recv_config(struct net *net, struct sock *ctnl,
873                               struct sk_buff *skb, const struct nlmsghdr *nlh,
874                               const struct nlattr * const nfula[],
875                               struct netlink_ext_ack *extack)
876 {
877         struct nfgenmsg *nfmsg = nlmsg_data(nlh);
878         u_int16_t group_num = ntohs(nfmsg->res_id);
879         struct nfulnl_instance *inst;
880         struct nfulnl_msg_config_cmd *cmd = NULL;
881         struct nfnl_log_net *log = nfnl_log_pernet(net);
882         int ret = 0;
883         u16 flags = 0;
884 
885         if (nfula[NFULA_CFG_CMD]) {
886                 u_int8_t pf = nfmsg->nfgen_family;
887                 cmd = nla_data(nfula[NFULA_CFG_CMD]);
888 
889                 /* Commands without queue context */
890                 switch (cmd->command) {
891                 case NFULNL_CFG_CMD_PF_BIND:
892                         return nf_log_bind_pf(net, pf, &nfulnl_logger);
893                 case NFULNL_CFG_CMD_PF_UNBIND:
894                         nf_log_unbind_pf(net, pf);
895                         return 0;
896                 }
897         }
898 
899         inst = instance_lookup_get(log, group_num);
900         if (inst && inst->peer_portid != NETLINK_CB(skb).portid) {
901                 ret = -EPERM;
902                 goto out_put;
903         }
904 
905         /* Check if we support these flags in first place, dependencies should
906          * be there too not to break atomicity.
907          */
908         if (nfula[NFULA_CFG_FLAGS]) {
909                 flags = ntohs(nla_get_be16(nfula[NFULA_CFG_FLAGS]));
910 
911                 if ((flags & NFULNL_CFG_F_CONNTRACK) &&
912                     !rcu_access_pointer(nfnl_ct_hook)) {
913 #ifdef CONFIG_MODULES
914                         nfnl_unlock(NFNL_SUBSYS_ULOG);
915                         request_module("ip_conntrack_netlink");
916                         nfnl_lock(NFNL_SUBSYS_ULOG);
917                         if (rcu_access_pointer(nfnl_ct_hook)) {
918                                 ret = -EAGAIN;
919                                 goto out_put;
920                         }
921 #endif
922                         ret = -EOPNOTSUPP;
923                         goto out_put;
924                 }
925         }
926 
927         if (cmd != NULL) {
928                 switch (cmd->command) {
929                 case NFULNL_CFG_CMD_BIND:
930                         if (inst) {
931                                 ret = -EBUSY;
932                                 goto out_put;
933                         }
934 
935                         inst = instance_create(net, group_num,
936                                                NETLINK_CB(skb).portid,
937                                                sk_user_ns(NETLINK_CB(skb).sk));
938                         if (IS_ERR(inst)) {
939                                 ret = PTR_ERR(inst);
940                                 goto out;
941                         }
942                         break;
943                 case NFULNL_CFG_CMD_UNBIND:
944                         if (!inst) {
945                                 ret = -ENODEV;
946                                 goto out;
947                         }
948 
949                         instance_destroy(log, inst);
950                         goto out_put;
951                 default:
952                         ret = -ENOTSUPP;
953                         goto out_put;
954                 }
955         } else if (!inst) {
956                 ret = -ENODEV;
957                 goto out;
958         }
959 
960         if (nfula[NFULA_CFG_MODE]) {
961                 struct nfulnl_msg_config_mode *params =
962                         nla_data(nfula[NFULA_CFG_MODE]);
963 
964                 nfulnl_set_mode(inst, params->copy_mode,
965                                 ntohl(params->copy_range));
966         }
967 
968         if (nfula[NFULA_CFG_TIMEOUT]) {
969                 __be32 timeout = nla_get_be32(nfula[NFULA_CFG_TIMEOUT]);
970 
971                 nfulnl_set_timeout(inst, ntohl(timeout));
972         }
973 
974         if (nfula[NFULA_CFG_NLBUFSIZ]) {
975                 __be32 nlbufsiz = nla_get_be32(nfula[NFULA_CFG_NLBUFSIZ]);
976 
977                 nfulnl_set_nlbufsiz(inst, ntohl(nlbufsiz));
978         }
979 
980         if (nfula[NFULA_CFG_QTHRESH]) {
981                 __be32 qthresh = nla_get_be32(nfula[NFULA_CFG_QTHRESH]);
982 
983                 nfulnl_set_qthresh(inst, ntohl(qthresh));
984         }
985 
986         if (nfula[NFULA_CFG_FLAGS])
987                 nfulnl_set_flags(inst, flags);
988 
989 out_put:
990         instance_put(inst);
991 out:
992         return ret;
993 }
994 
995 static const struct nfnl_callback nfulnl_cb[NFULNL_MSG_MAX] = {
996         [NFULNL_MSG_PACKET]     = { .call = nfulnl_recv_unsupp,
997                                     .attr_count = NFULA_MAX, },
998         [NFULNL_MSG_CONFIG]     = { .call = nfulnl_recv_config,
999                                     .attr_count = NFULA_CFG_MAX,
1000                                     .policy = nfula_cfg_policy },
1001 };
1002 
1003 static const struct nfnetlink_subsystem nfulnl_subsys = {
1004         .name           = "log",
1005         .subsys_id      = NFNL_SUBSYS_ULOG,
1006         .cb_count       = NFULNL_MSG_MAX,
1007         .cb             = nfulnl_cb,
1008 };
1009 
1010 #ifdef CONFIG_PROC_FS
1011 struct iter_state {
1012         struct seq_net_private p;
1013         unsigned int bucket;
1014 };
1015 
1016 static struct hlist_node *get_first(struct net *net, struct iter_state *st)
1017 {
1018         struct nfnl_log_net *log;
1019         if (!st)
1020                 return NULL;
1021 
1022         log = nfnl_log_pernet(net);
1023 
1024         for (st->bucket = 0; st->bucket < INSTANCE_BUCKETS; st->bucket++) {
1025                 struct hlist_head *head = &log->instance_table[st->bucket];
1026 
1027                 if (!hlist_empty(head))
1028                         return rcu_dereference_bh(hlist_first_rcu(head));
1029         }
1030         return NULL;
1031 }
1032 
1033 static struct hlist_node *get_next(struct net *net, struct iter_state *st,
1034                                    struct hlist_node *h)
1035 {
1036         h = rcu_dereference_bh(hlist_next_rcu(h));
1037         while (!h) {
1038                 struct nfnl_log_net *log;
1039                 struct hlist_head *head;
1040 
1041                 if (++st->bucket >= INSTANCE_BUCKETS)
1042                         return NULL;
1043 
1044                 log = nfnl_log_pernet(net);
1045                 head = &log->instance_table[st->bucket];
1046                 h = rcu_dereference_bh(hlist_first_rcu(head));
1047         }
1048         return h;
1049 }
1050 
1051 static struct hlist_node *get_idx(struct net *net, struct iter_state *st,
1052                                   loff_t pos)
1053 {
1054         struct hlist_node *head;
1055         head = get_first(net, st);
1056 
1057         if (head)
1058                 while (pos && (head = get_next(net, st, head)))
1059                         pos--;
1060         return pos ? NULL : head;
1061 }
1062 
1063 static void *seq_start(struct seq_file *s, loff_t *pos)
1064         __acquires(rcu_bh)
1065 {
1066         rcu_read_lock_bh();
1067         return get_idx(seq_file_net(s), s->private, *pos);
1068 }
1069 
1070 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
1071 {
1072         (*pos)++;
1073         return get_next(seq_file_net(s), s->private, v);
1074 }
1075 
1076 static void seq_stop(struct seq_file *s, void *v)
1077         __releases(rcu_bh)
1078 {
1079         rcu_read_unlock_bh();
1080 }
1081 
1082 static int seq_show(struct seq_file *s, void *v)
1083 {
1084         const struct nfulnl_instance *inst = v;
1085 
1086         seq_printf(s, "%5u %6u %5u %1u %5u %6u %2u\n",
1087                    inst->group_num,
1088                    inst->peer_portid, inst->qlen,
1089                    inst->copy_mode, inst->copy_range,
1090                    inst->flushtimeout, refcount_read(&inst->use));
1091 
1092         return 0;
1093 }
1094 
1095 static const struct seq_operations nful_seq_ops = {
1096         .start  = seq_start,
1097         .next   = seq_next,
1098         .stop   = seq_stop,
1099         .show   = seq_show,
1100 };
1101 #endif /* PROC_FS */
1102 
1103 static int __net_init nfnl_log_net_init(struct net *net)
1104 {
1105         unsigned int i;
1106         struct nfnl_log_net *log = nfnl_log_pernet(net);
1107 #ifdef CONFIG_PROC_FS
1108         struct proc_dir_entry *proc;
1109         kuid_t root_uid;
1110         kgid_t root_gid;
1111 #endif
1112 
1113         for (i = 0; i < INSTANCE_BUCKETS; i++)
1114                 INIT_HLIST_HEAD(&log->instance_table[i]);
1115         spin_lock_init(&log->instances_lock);
1116 
1117 #ifdef CONFIG_PROC_FS
1118         proc = proc_create_net("nfnetlink_log", 0440, net->nf.proc_netfilter,
1119                         &nful_seq_ops, sizeof(struct iter_state));
1120         if (!proc)
1121                 return -ENOMEM;
1122 
1123         root_uid = make_kuid(net->user_ns, 0);
1124         root_gid = make_kgid(net->user_ns, 0);
1125         if (uid_valid(root_uid) && gid_valid(root_gid))
1126                 proc_set_user(proc, root_uid, root_gid);
1127 #endif
1128         return 0;
1129 }
1130 
1131 static void __net_exit nfnl_log_net_exit(struct net *net)
1132 {
1133         struct nfnl_log_net *log = nfnl_log_pernet(net);
1134         unsigned int i;
1135 
1136 #ifdef CONFIG_PROC_FS
1137         remove_proc_entry("nfnetlink_log", net->nf.proc_netfilter);
1138 #endif
1139         nf_log_unset(net, &nfulnl_logger);
1140         for (i = 0; i < INSTANCE_BUCKETS; i++)
1141                 WARN_ON_ONCE(!hlist_empty(&log->instance_table[i]));
1142 }
1143 
1144 static struct pernet_operations nfnl_log_net_ops = {
1145         .init   = nfnl_log_net_init,
1146         .exit   = nfnl_log_net_exit,
1147         .id     = &nfnl_log_net_id,
1148         .size   = sizeof(struct nfnl_log_net),
1149 };
1150 
1151 static int __init nfnetlink_log_init(void)
1152 {
1153         int status;
1154 
1155         status = register_pernet_subsys(&nfnl_log_net_ops);
1156         if (status < 0) {
1157                 pr_err("failed to register pernet ops\n");
1158                 goto out;
1159         }
1160 
1161         netlink_register_notifier(&nfulnl_rtnl_notifier);
1162         status = nfnetlink_subsys_register(&nfulnl_subsys);
1163         if (status < 0) {
1164                 pr_err("failed to create netlink socket\n");
1165                 goto cleanup_netlink_notifier;
1166         }
1167 
1168         status = nf_log_register(NFPROTO_UNSPEC, &nfulnl_logger);
1169         if (status < 0) {
1170                 pr_err("failed to register logger\n");
1171                 goto cleanup_subsys;
1172         }
1173 
1174         return status;
1175 
1176 cleanup_subsys:
1177         nfnetlink_subsys_unregister(&nfulnl_subsys);
1178 cleanup_netlink_notifier:
1179         netlink_unregister_notifier(&nfulnl_rtnl_notifier);
1180         unregister_pernet_subsys(&nfnl_log_net_ops);
1181 out:
1182         return status;
1183 }
1184 
1185 static void __exit nfnetlink_log_fini(void)
1186 {
1187         nfnetlink_subsys_unregister(&nfulnl_subsys);
1188         netlink_unregister_notifier(&nfulnl_rtnl_notifier);
1189         unregister_pernet_subsys(&nfnl_log_net_ops);
1190         nf_log_unregister(&nfulnl_logger);
1191 }
1192 
1193 MODULE_DESCRIPTION("netfilter userspace logging");
1194 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
1195 MODULE_LICENSE("GPL");
1196 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ULOG);
1197 MODULE_ALIAS_NF_LOGGER(AF_INET, 1);
1198 MODULE_ALIAS_NF_LOGGER(AF_INET6, 1);
1199 MODULE_ALIAS_NF_LOGGER(AF_BRIDGE, 1);
1200 MODULE_ALIAS_NF_LOGGER(3, 1); /* NFPROTO_ARP */
1201 MODULE_ALIAS_NF_LOGGER(5, 1); /* NFPROTO_NETDEV */
1202 
1203 module_init(nfnetlink_log_init);
1204 module_exit(nfnetlink_log_fini);
1205 

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