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71d8c47fc6
This patch introduces nf_ct_resolve_clash() to resolve race condition on conntrack insertions. This is particularly a problem for connection-less protocols such as UDP, with no initial handshake. Two or more packets may race to insert the entry resulting in packet drops. Another problematic scenario are packets enqueued to userspace via NFQUEUE after the raw table, that make it easier to trigger this race. To resolve this, the idea is to reset the conntrack entry to the one that won race. Packet and bytes counters are also merged. The 'insert_failed' stats still accounts for this situation, after this patch, the drop counter is bumped whenever we drop packets, so we can watch for unresolved clashes. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
161 lines
5.1 KiB
C
161 lines
5.1 KiB
C
/*
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* Header for use in defining a given L4 protocol for connection tracking.
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*
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* 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
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* - generalized L3 protocol dependent part.
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*
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* Derived from include/linux/netfiter_ipv4/ip_conntrack_protcol.h
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*/
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#ifndef _NF_CONNTRACK_L4PROTO_H
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#define _NF_CONNTRACK_L4PROTO_H
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#include <linux/netlink.h>
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#include <net/netlink.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netns/generic.h>
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struct seq_file;
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struct nf_conntrack_l4proto {
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/* L3 Protocol number. */
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u_int16_t l3proto;
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/* L4 Protocol number. */
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u_int8_t l4proto;
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/* Resolve clashes on insertion races. */
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bool allow_clash;
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/* Try to fill in the third arg: dataoff is offset past network protocol
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hdr. Return true if possible. */
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bool (*pkt_to_tuple)(const struct sk_buff *skb, unsigned int dataoff,
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struct net *net, struct nf_conntrack_tuple *tuple);
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/* Invert the per-proto part of the tuple: ie. turn xmit into reply.
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* Some packets can't be inverted: return 0 in that case.
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*/
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bool (*invert_tuple)(struct nf_conntrack_tuple *inverse,
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const struct nf_conntrack_tuple *orig);
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/* Returns verdict for packet, or -1 for invalid. */
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int (*packet)(struct nf_conn *ct,
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const struct sk_buff *skb,
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unsigned int dataoff,
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enum ip_conntrack_info ctinfo,
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u_int8_t pf,
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unsigned int hooknum,
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unsigned int *timeouts);
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/* Called when a new connection for this protocol found;
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* returns TRUE if it's OK. If so, packet() called next. */
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bool (*new)(struct nf_conn *ct, const struct sk_buff *skb,
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unsigned int dataoff, unsigned int *timeouts);
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/* Called when a conntrack entry is destroyed */
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void (*destroy)(struct nf_conn *ct);
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int (*error)(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
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unsigned int dataoff, enum ip_conntrack_info *ctinfo,
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u_int8_t pf, unsigned int hooknum);
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/* Print out the per-protocol part of the tuple. Return like seq_* */
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void (*print_tuple)(struct seq_file *s,
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const struct nf_conntrack_tuple *);
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/* Print out the private part of the conntrack. */
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void (*print_conntrack)(struct seq_file *s, struct nf_conn *);
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/* Return the array of timeouts for this protocol. */
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unsigned int *(*get_timeouts)(struct net *net);
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/* convert protoinfo to nfnetink attributes */
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int (*to_nlattr)(struct sk_buff *skb, struct nlattr *nla,
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struct nf_conn *ct);
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/* Calculate protoinfo nlattr size */
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int (*nlattr_size)(void);
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/* convert nfnetlink attributes to protoinfo */
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int (*from_nlattr)(struct nlattr *tb[], struct nf_conn *ct);
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int (*tuple_to_nlattr)(struct sk_buff *skb,
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const struct nf_conntrack_tuple *t);
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/* Calculate tuple nlattr size */
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int (*nlattr_tuple_size)(void);
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int (*nlattr_to_tuple)(struct nlattr *tb[],
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struct nf_conntrack_tuple *t);
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const struct nla_policy *nla_policy;
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size_t nla_size;
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#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
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struct {
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size_t obj_size;
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int (*nlattr_to_obj)(struct nlattr *tb[],
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struct net *net, void *data);
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int (*obj_to_nlattr)(struct sk_buff *skb, const void *data);
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unsigned int nlattr_max;
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const struct nla_policy *nla_policy;
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} ctnl_timeout;
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#endif
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int *net_id;
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/* Init l4proto pernet data */
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int (*init_net)(struct net *net, u_int16_t proto);
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/* Return the per-net protocol part. */
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struct nf_proto_net *(*get_net_proto)(struct net *net);
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/* Protocol name */
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const char *name;
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/* Module (if any) which this is connected to. */
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struct module *me;
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};
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/* Existing built-in generic protocol */
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extern struct nf_conntrack_l4proto nf_conntrack_l4proto_generic;
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#define MAX_NF_CT_PROTO 256
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struct nf_conntrack_l4proto *__nf_ct_l4proto_find(u_int16_t l3proto,
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u_int8_t l4proto);
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struct nf_conntrack_l4proto *nf_ct_l4proto_find_get(u_int16_t l3proto,
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u_int8_t l4proto);
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void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p);
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/* Protocol pernet registration. */
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int nf_ct_l4proto_pernet_register(struct net *net,
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struct nf_conntrack_l4proto *proto);
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void nf_ct_l4proto_pernet_unregister(struct net *net,
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struct nf_conntrack_l4proto *proto);
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/* Protocol global registration. */
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int nf_ct_l4proto_register(struct nf_conntrack_l4proto *proto);
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void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *proto);
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static inline void nf_ct_kfree_compat_sysctl_table(struct nf_proto_net *pn)
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{
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#if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
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kfree(pn->ctl_compat_table);
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pn->ctl_compat_table = NULL;
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#endif
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}
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/* Generic netlink helpers */
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int nf_ct_port_tuple_to_nlattr(struct sk_buff *skb,
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const struct nf_conntrack_tuple *tuple);
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int nf_ct_port_nlattr_to_tuple(struct nlattr *tb[],
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struct nf_conntrack_tuple *t);
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int nf_ct_port_nlattr_tuple_size(void);
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extern const struct nla_policy nf_ct_port_nla_policy[];
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#ifdef CONFIG_SYSCTL
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#define LOG_INVALID(net, proto) \
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((net)->ct.sysctl_log_invalid == (proto) || \
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(net)->ct.sysctl_log_invalid == IPPROTO_RAW)
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#else
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static inline int LOG_INVALID(struct net *net, int proto) { return 0; }
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#endif /* CONFIG_SYSCTL */
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#endif /*_NF_CONNTRACK_PROTOCOL_H*/
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