static unsigned int ipv4_conntrack_defrag(const struct nf_hook_ops *ops, struct sk_buff *skb, const struct nf_hook_state *state) { struct sock *sk = skb->sk; struct inet_sock *inet = inet_sk(skb->sk); if (sk && (sk->sk_family == PF_INET) && inet->nodefrag) return NF_ACCEPT; #if IS_ENABLED(CONFIG_NF_CONNTRACK) #if !IS_ENABLED(CONFIG_NF_NAT) /* Previously seen (loopback)? Ignore. Do this before fragment check. */ if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct)) return NF_ACCEPT; #endif #endif /* Gather fragments. */ if (ip_is_fragment(ip_hdr(skb))) { enum ip_defrag_users user = nf_ct_defrag_user(ops->hooknum, skb); if (nf_ct_ipv4_gather_frags(skb, user)) return NF_STOLEN; } return NF_ACCEPT; }
static unsigned int ipv6_defrag(unsigned int hooknum, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *reasm; #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) /* Previously seen (loopback)? */ if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct)) return NF_ACCEPT; #endif reasm = nf_ct_frag6_gather(skb, nf_ct6_defrag_user(hooknum, skb)); /* queued */ if (reasm == NULL) return NF_STOLEN; /* error occurred or not fragmented */ if (reasm == skb) return NF_ACCEPT; nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in, (struct net_device *)out, okfn); return NF_STOLEN; }
static unsigned int ipv4_conntrack_defrag(unsigned int hooknum, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sock *sk = skb->sk; struct inet_sock *inet = inet_sk(skb->sk); if (sk && (sk->sk_family == PF_INET) && inet->nodefrag) return NF_ACCEPT; #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) #if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE) /* Previously seen (loopback)? Ignore. Do this before fragment check. */ if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct)) return NF_ACCEPT; #endif #endif /* Gather fragments. */ if (ip_is_fragment(ip_hdr(skb))) { enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb); if (nf_ct_ipv4_gather_frags(skb, user)) return NF_STOLEN; } return NF_ACCEPT; }
static unsigned int ipv6_defrag(const struct nf_hook_ops *ops, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *reasm; #if IS_ENABLED(CONFIG_NF_CONNTRACK) /* Previously seen (loopback)? */ if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct)) return NF_ACCEPT; #endif reasm = nf_ct_frag6_gather(skb, nf_ct6_defrag_user(ops->hooknum, skb)); /* queued */ if (reasm == NULL) return NF_STOLEN; /* error occurred or not fragmented */ if (reasm == skb) return NF_ACCEPT; nf_ct_frag6_consume_orig(reasm); NF_HOOK_THRESH(NFPROTO_IPV6, ops->hooknum, reasm, (struct net_device *) in, (struct net_device *) out, okfn, NF_IP6_PRI_CONNTRACK_DEFRAG + 1); return NF_STOLEN; }
//只有当IP分片重组成功时,nf_ct_ipv4_gather_frags才会返回为0。也就是说,当IP分片重组不成功,即IP分片被kernel分片模块缓存时,该函数返回为NF_STOLEN。 unsigned int ipv4_conntrack_defrag2(unsigned int hooknum, struct sk_buff *skb) { #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) #if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE) /* Previously seen (loopback)? Ignore. Do this before fragment check. */ if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct)) return NF_ACCEPT; #endif #endif /* Gather fragments. */ if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) { enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb); if (nf_ct_ipv4_gather_frags(skb, user)) return NF_STOLEN; } return NF_ACCEPT; }
static unsigned int ipv6_defrag(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { int err; #if IS_ENABLED(CONFIG_NF_CONNTRACK) /* Previously seen (loopback)? */ if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct)) return NF_ACCEPT; #endif err = nf_ct_frag6_gather(state->net, skb, nf_ct6_defrag_user(state->hook, skb)); /* queued */ if (err == -EINPROGRESS) return NF_STOLEN; return err == 0 ? NF_ACCEPT : NF_DROP; }
static unsigned int ipv4_conntrack_local(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { if (ip_is_fragment(ip_hdr(skb))) { /* IP_NODEFRAG setsockopt set */ enum ip_conntrack_info ctinfo; struct nf_conn *tmpl; tmpl = nf_ct_get(skb, &ctinfo); if (tmpl && nf_ct_is_template(tmpl)) { /* when skipping ct, clear templates to avoid fooling * later targets/matches */ skb->_nfct = 0; nf_ct_put(tmpl); } return NF_ACCEPT; } return nf_conntrack_in(state->net, PF_INET, state->hook, skb); }