cregit-Linux how code gets into the kernel

Release 4.8 net/netfilter/nfnetlink_queue.c

Directory: net/netfilter
/*
 * This is a module which is used for queueing packets and communicating with
 * userspace via nfnetlink.
 *
 * (C) 2005 by Harald Welte <laforge@netfilter.org>
 * (C) 2007 by Patrick McHardy <kaber@trash.net>
 *
 * Based on the old ipv4-only ip_queue.c:
 * (C) 2000-2002 James Morris <jmorris@intercode.com.au>
 * (C) 2003-2005 Netfilter Core Team <coreteam@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/proc_fs.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_queue.h>
#include <linux/netfilter/nf_conntrack_common.h>
#include <linux/list.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/netfilter/nf_queue.h>
#include <net/netns/generic.h>

#include <linux/atomic.h>

#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
#include "../bridge/br_private.h"
#endif


#define NFQNL_QMAX_DEFAULT 1024

/* We're using struct nlattr which has 16bit nla_len. Note that nla_len
 * includes the header length. Thus, the maximum packet length that we
 * support is 65531 bytes. We send truncated packets if the specified length
 * is larger than that.  Userspace can check for presence of NFQA_CAP_LEN
 * attribute to detect truncation.
 */

#define NFQNL_MAX_COPY_RANGE (0xffff - NLA_HDRLEN)


struct nfqnl_instance {
	
struct hlist_node hlist;		/* global list of queues */
	
struct rcu_head rcu;

	
u32 peer_portid;
	
unsigned int queue_maxlen;
	
unsigned int copy_range;
	
unsigned int queue_dropped;
	
unsigned int queue_user_dropped;


	
u_int16_t queue_num;			/* number of this queue */
	
u_int8_t copy_mode;
	
u_int32_t flags;			/* Set using NFQA_CFG_FLAGS */
/*
 * Following fields are dirtied for each queued packet,
 * keep them in same cache line if possible.
 */
	
spinlock_t	lock;
	
unsigned int	queue_total;
	
unsigned int	id_sequence;		/* 'sequence' of pkt ids */
	
struct list_head queue_list;		/* packets in queue */
};


typedef int (*nfqnl_cmpfn)(struct nf_queue_entry *, unsigned long);


static int nfnl_queue_net_id __read_mostly;


#define INSTANCE_BUCKETS	16

struct nfnl_queue_net {
	
spinlock_t instances_lock;
	
struct hlist_head instance_table[INSTANCE_BUCKETS];
};


static struct nfnl_queue_net *nfnl_queue_pernet(struct net *net) { return net_generic(net, nfnl_queue_net_id); }

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static inline u_int8_t instance_hashfn(u_int16_t queue_num) { return ((queue_num >> 8) ^ queue_num) % INSTANCE_BUCKETS; }

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static struct nfqnl_instance * instance_lookup(struct nfnl_queue_net *q, u_int16_t queue_num) { struct hlist_head *head; struct nfqnl_instance *inst; head = &q->instance_table[instance_hashfn(queue_num)]; hlist_for_each_entry_rcu(inst, head, hlist) { if (inst->queue_num == queue_num) return inst; } return NULL; }

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static struct nfqnl_instance * instance_create(struct nfnl_queue_net *q, u_int16_t queue_num, u32 portid) { struct nfqnl_instance *inst; unsigned int h; int err; spin_lock(&q->instances_lock); if (instance_lookup(q, queue_num)) { err = -EEXIST; goto out_unlock; } inst = kzalloc(sizeof(*inst), GFP_ATOMIC); if (!inst) { err = -ENOMEM; goto out_unlock; } inst->queue_num = queue_num; inst->peer_portid = portid; inst->queue_maxlen = NFQNL_QMAX_DEFAULT; inst->copy_range = NFQNL_MAX_COPY_RANGE; inst->copy_mode = NFQNL_COPY_NONE; spin_lock_init(&inst->lock); INIT_LIST_HEAD(&inst->queue_list); if (!try_module_get(THIS_MODULE)) { err = -EAGAIN; goto out_free; } h = instance_hashfn(queue_num); hlist_add_head_rcu(&inst->hlist, &q->instance_table[h]); spin_unlock(&q->instances_lock); return inst; out_free: kfree(inst); out_unlock: spin_unlock(&q->instances_lock); return ERR_PTR(err); }

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static void nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, unsigned long data);
static void instance_destroy_rcu(struct rcu_head *head) { struct nfqnl_instance *inst = container_of(head, struct nfqnl_instance, rcu); nfqnl_flush(inst, NULL, 0); kfree(inst); module_put(THIS_MODULE); }

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static void __instance_destroy(struct nfqnl_instance *inst) { hlist_del_rcu(&inst->hlist); call_rcu(&inst->rcu, instance_destroy_rcu); }

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static void instance_destroy(struct nfnl_queue_net *q, struct nfqnl_instance *inst) { spin_lock(&q->instances_lock); __instance_destroy(inst); spin_unlock(&q->instances_lock); }

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static inline void __enqueue_entry(struct nfqnl_instance *queue, struct nf_queue_entry *entry) { list_add_tail(&entry->list, &queue->queue_list); queue->queue_total++; }

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static void __dequeue_entry(struct nfqnl_instance *queue, struct nf_queue_entry *entry) { list_del(&entry->list); queue->queue_total--; }

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static struct nf_queue_entry * find_dequeue_entry(struct nfqnl_instance *queue, unsigned int id) { struct nf_queue_entry *entry = NULL, *i; spin_lock_bh(&queue->lock); list_for_each_entry(i, &queue->queue_list, list) { if (i->id == id) { entry = i; break; } } if (entry) __dequeue_entry(queue, entry); spin_unlock_bh(&queue->lock); return entry; }

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static void nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, unsigned long data) { struct nf_queue_entry *entry, *next; spin_lock_bh(&queue->lock); list_for_each_entry_safe(entry, next, &queue->queue_list, list) { if (!cmpfn || cmpfn(entry, data)) { list_del(&entry->list); queue->queue_total--; nf_reinject(entry, NF_DROP); } } spin_unlock_bh(&queue->lock); }

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static int nfqnl_put_packet_info(struct sk_buff *nlskb, struct sk_buff *packet, bool csum_verify) { __u32 flags = 0; if (packet->ip_summed == CHECKSUM_PARTIAL) flags = NFQA_SKB_CSUMNOTREADY; else if (csum_verify) flags = NFQA_SKB_CSUM_NOTVERIFIED; if (skb_is_gso(packet)) flags |= NFQA_SKB_GSO; return flags ? nla_put_be32(nlskb, NFQA_SKB_INFO, htonl(flags)) : 0; }

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static int nfqnl_put_sk_uidgid(struct sk_buff *skb, struct sock *sk) { const struct cred *cred; if (!sk_fullsock(sk)) return 0; read_lock_bh(&sk->sk_callback_lock); if (sk->sk_socket && sk->sk_socket->file) { cred = sk->sk_socket->file->f_cred; if (nla_put_be32(skb, NFQA_UID, htonl(from_kuid_munged(&init_user_ns, cred->fsuid)))) goto nla_put_failure; if (nla_put_be32(skb, NFQA_GID, htonl(from_kgid_munged(&init_user_ns, cred->fsgid)))) goto nla_put_failure; } read_unlock_bh(&sk->sk_callback_lock); return 0; nla_put_failure: read_unlock_bh(&sk->sk_callback_lock); return -1; }

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static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata) { u32 seclen = 0; #if IS_ENABLED(CONFIG_NETWORK_SECMARK) if (!skb || !sk_fullsock(skb->sk)) return 0; read_lock_bh(&skb->sk->sk_callback_lock); if (skb->secmark) security_secid_to_secctx(skb->secmark, secdata, &seclen); read_unlock_bh(&skb->sk->sk_callback_lock); #endif return seclen; }

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static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry) { struct sk_buff *entskb = entry->skb; u32 nlalen = 0; if (entry->state.pf != PF_BRIDGE || !skb_mac_header_was_set(entskb)) return 0; if (skb_vlan_tag_present(entskb)) nlalen += nla_total_size(nla_total_size(sizeof(__be16)) + nla_total_size(sizeof(__be16))); if (entskb->network_header > entskb->mac_header) nlalen += nla_total_size((entskb->network_header - entskb->mac_header)); return nlalen; }

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static int nfqnl_put_bridge(struct nf_queue_entry *entry, struct sk_buff *skb) { struct sk_buff *entskb = entry->skb; if (entry->state.pf != PF_BRIDGE || !skb_mac_header_was_set(entskb)) return 0; if (skb_vlan_tag_present(entskb)) { struct nlattr *nest; nest = nla_nest_start(skb, NFQA_VLAN | NLA_F_NESTED); if (!nest) goto nla_put_failure; if (nla_put_be16(skb, NFQA_VLAN_TCI, htons(entskb->vlan_tci)) || nla_put_be16(skb, NFQA_VLAN_PROTO, entskb->vlan_proto)) goto nla_put_failure; nla_nest_end(skb, nest); } if (entskb->mac_header < entskb->network_header) { int len = (int)(entskb->network_header - entskb->mac_header); if (nla_put(skb, NFQA_L2HDR, len, skb_mac_header(entskb))) goto nla_put_failure; } return 0; nla_put_failure: return -1; }

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static struct sk_buff * nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, struct nf_queue_entry *entry, __be32 **packet_id_ptr) { size_t size; size_t data_len = 0, cap_len = 0; unsigned int hlen = 0; struct sk_buff *skb; struct nlattr *nla; struct nfqnl_msg_packet_hdr *pmsg; struct nlmsghdr *nlh; struct nfgenmsg *nfmsg; struct sk_buff *entskb = entry->skb; struct net_device *indev; struct net_device *outdev; struct nf_conn *ct = NULL; enum ip_conntrack_info uninitialized_var(ctinfo); struct nfnl_ct_hook *nfnl_ct; bool csum_verify; char *secdata = NULL; u32 seclen = 0; size = nlmsg_total_size(sizeof(struct nfgenmsg)) + nla_total_size(sizeof(struct nfqnl_msg_packet_hdr)) + nla_total_size(sizeof(u_int32_t)) /* ifindex */ + nla_total_size(sizeof(u_int32_t)) /* ifindex */ #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + nla_total_size(sizeof(u_int32_t)) /* ifindex */ + nla_total_size(sizeof(u_int32_t)) /* ifindex */ #endif + nla_total_size(sizeof(u_int32_t)) /* mark */ + nla_total_size(sizeof(struct nfqnl_msg_packet_hw)) + nla_total_size(sizeof(u_int32_t)) /* skbinfo */ + nla_total_size(sizeof(u_int32_t)); /* cap_len */ if (entskb->tstamp.tv64) size += nla_total_size(sizeof(struct nfqnl_msg_packet_timestamp)); size += nfqnl_get_bridge_size(entry); if (entry->state.hook <= NF_INET_FORWARD || (entry->state.hook == NF_INET_POST_ROUTING && entskb->sk == NULL)) csum_verify = !skb_csum_unnecessary(entskb); else csum_verify = false; outdev = entry->state.out; switch ((enum nfqnl_config_mode)ACCESS_ONCE(queue->copy_mode)) { case NFQNL_COPY_META: case NFQNL_COPY_NONE: break; case NFQNL_COPY_PACKET: if (!(queue->flags & NFQA_CFG_F_GSO) && entskb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(entskb)) return NULL; data_len = ACCESS_ONCE(queue->copy_range); if (data_len > entskb->len) data_len = entskb->len; hlen = skb_zerocopy_headlen(entskb); hlen = min_t(unsigned int, hlen, data_len); size += sizeof(struct nlattr) + hlen; cap_len = entskb->len; break; } nfnl_ct = rcu_dereference(nfnl_ct_hook); if (queue->flags & NFQA_CFG_F_CONNTRACK) { if (nfnl_ct != NULL) { ct = nfnl_ct->get_ct(entskb, &ctinfo); if (ct != NULL) size += nfnl_ct->build_size(ct); } } if (queue->flags & NFQA_CFG_F_UID_GID) { size += (nla_total_size(sizeof(u_int32_t)) /* uid */ + nla_total_size(sizeof(u_int32_t))); /* gid */ } if ((queue->flags & NFQA_CFG_F_SECCTX) && entskb->sk) { seclen = nfqnl_get_sk_secctx(entskb, &secdata); if (seclen) size += nla_total_size(seclen); } skb = alloc_skb(size, GFP_ATOMIC); if (!skb) { skb_tx_error(entskb); return NULL; } nlh = nlmsg_put(skb, 0, 0, NFNL_SUBSYS_QUEUE << 8 | NFQNL_MSG_PACKET, sizeof(struct nfgenmsg), 0); if (!nlh) { skb_tx_error(entskb); kfree_skb(skb); return NULL; } nfmsg = nlmsg_data(nlh); nfmsg->nfgen_family = entry->state.pf; nfmsg->version = NFNETLINK_V0; nfmsg->res_id = htons(queue->queue_num); nla = __nla_reserve(skb, NFQA_PACKET_HDR, sizeof(*pmsg)); pmsg = nla_data(nla); pmsg->hw_protocol = entskb->protocol; pmsg->hook = entry->state.hook; *packet_id_ptr = &pmsg->packet_id; indev = entry->state.in; if (indev) { #if !IS_ENABLED(CONFIG_BRIDGE_NETFILTER) if (nla_put_be32(skb, NFQA_IFINDEX_INDEV, htonl(indev->ifindex))) goto nla_put_failure; #else if (entry->state.pf == PF_BRIDGE) { /* Case 1: indev is physical input device, we need to * look for bridge group (when called from * netfilter_bridge) */ if (nla_put_be32(skb, NFQA_IFINDEX_PHYSINDEV, htonl(indev->ifindex)) || /* this is the bridge group "brX" */ /* rcu_read_lock()ed by __nf_queue */ nla_put_be32(skb, NFQA_IFINDEX_INDEV, htonl(br_port_get_rcu(indev)->br->dev->ifindex))) goto nla_put_failure; } else { int physinif; /* Case 2: indev is bridge group, we need to look for * physical device (when called from ipv4) */ if (nla_put_be32(skb, NFQA_IFINDEX_INDEV, htonl(indev->ifindex))) goto nla_put_failure; physinif = nf_bridge_get_physinif(entskb); if (physinif && nla_put_be32(skb, NFQA_IFINDEX_PHYSINDEV, htonl(physinif))) goto nla_put_failure; } #endif } if (outdev) { #if !IS_ENABLED(CONFIG_BRIDGE_NETFILTER) if (nla_put_be32(skb, NFQA_IFINDEX_OUTDEV, htonl(outdev->ifindex))) goto nla_put_failure; #else if (entry->state.pf == PF_BRIDGE) { /* Case 1: outdev is physical output device, we need to * look for bridge group (when called from * netfilter_bridge) */ if (nla_put_be32(skb, NFQA_IFINDEX_PHYSOUTDEV, htonl(outdev->ifindex)) || /* this is the bridge group "brX" */ /* rcu_read_lock()ed by __nf_queue */ nla_put_be32(skb, NFQA_IFINDEX_OUTDEV, htonl(br_port_get_rcu(outdev)->br->dev->ifindex))) goto nla_put_failure; } else { int physoutif; /* Case 2: outdev is bridge group, we need to look for * physical output device (when called from ipv4) */ if (nla_put_be32(skb, NFQA_IFINDEX_OUTDEV, htonl(outdev->ifindex))) goto nla_put_failure; physoutif = nf_bridge_get_physoutif(entskb); if (physoutif && nla_put_be32(skb, NFQA_IFINDEX_PHYSOUTDEV, htonl(physoutif))) goto nla_put_failure; } #endif } if (entskb->mark && nla_put_be32(skb, NFQA_MARK, htonl(entskb->mark))) goto nla_put_failure; if (indev && entskb->dev && entskb->mac_header != entskb->network_header) { struct nfqnl_msg_packet_hw phw; int len; memset(&phw, 0, sizeof(phw)); len = dev_parse_header(entskb, phw.hw_addr); if (len) { phw.hw_addrlen = htons(len); if (nla_put(skb, NFQA_HWADDR, sizeof(phw), &phw)) goto nla_put_failure; } } if (nfqnl_put_bridge(entry, skb) < 0) goto nla_put_failure; if (entskb->tstamp.tv64) { struct nfqnl_msg_packet_timestamp ts; struct timespec64 kts = ktime_to_timespec64(entskb->tstamp); ts.sec = cpu_to_be64(kts.tv_sec); ts.usec = cpu_to_be64(kts.tv_nsec / NSEC_PER_USEC); if (nla_put(skb, NFQA_TIMESTAMP, sizeof(ts), &ts)) goto nla_put_failure; } if ((queue->flags & NFQA_CFG_F_UID_GID) && entskb->sk && nfqnl_put_sk_uidgid(skb, entskb->sk) < 0) goto nla_put_failure; if (seclen && nla_put(skb, NFQA_SECCTX, seclen, secdata)) goto nla_put_failure; if (ct && nfnl_ct->build(skb, ct, ctinfo, NFQA_CT, NFQA_CT_INFO) < 0) goto nla_put_failure; if (cap_len > data_len && nla_put_be32(skb, NFQA_CAP_LEN, htonl(cap_len))) goto nla_put_failure; if (nfqnl_put_packet_info(skb, entskb, csum_verify)) goto nla_put_failure; if (data_len) { struct nlattr *nla; if (skb_tailroom(skb) < sizeof(*nla) + hlen) goto nla_put_failure; nla = (struct nlattr *)skb_put(skb, sizeof(*nla))