cregit-Linux how code gets into the kernel

Release 4.11 net/openvswitch/conntrack.c

Directory: net/openvswitch
/*
 * Copyright (c) 2015 Nicira, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */

#include <linux/module.h>
#include <linux/openvswitch.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/sctp.h>
#include <net/ip.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_labels.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>

#ifdef CONFIG_NF_NAT_NEEDED
#include <linux/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_l3proto.h>
#endif

#include "datapath.h"
#include "conntrack.h"
#include "flow.h"
#include "flow_netlink.h"


struct ovs_ct_len_tbl {
	
int maxlen;
	
int minlen;
};

/* Metadata mark for masked write to conntrack mark */

struct md_mark {
	
u32 value;
	
u32 mask;
};

/* Metadata label for masked write to conntrack label. */

struct md_labels {
	
struct ovs_key_ct_labels value;
	
struct ovs_key_ct_labels mask;
};


enum ovs_ct_nat {
	
OVS_CT_NAT = 1 << 0,     /* NAT for committed connections only. */
	
OVS_CT_SRC_NAT = 1 << 1, /* Source NAT for NEW connections. */
	
OVS_CT_DST_NAT = 1 << 2, /* Destination NAT for NEW connections. */
};

/* Conntrack action context for execution. */

struct ovs_conntrack_info {
	
struct nf_conntrack_helper *helper;
	
struct nf_conntrack_zone zone;
	
struct nf_conn *ct;
	
u8 commit : 1;
	
u8 nat : 3;                 /* enum ovs_ct_nat */
	
u8 force : 1;
	
u16 family;
	
struct md_mark mark;
	
struct md_labels labels;
#ifdef CONFIG_NF_NAT_NEEDED
	
struct nf_nat_range range;  /* Only present for SRC NAT and DST NAT. */
#endif
};

static bool labels_nonzero(const struct ovs_key_ct_labels *labels);

static void __ovs_ct_free_action(struct ovs_conntrack_info *ct_info);


static u16 key_to_nfproto(const struct sw_flow_key *key) { switch (ntohs(key->eth.type)) { case ETH_P_IP: return NFPROTO_IPV4; case ETH_P_IPV6: return NFPROTO_IPV6; default: return NFPROTO_UNSPEC; } }

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/* Map SKB connection state into the values used by flow definition. */
static u8 ovs_ct_get_state(enum ip_conntrack_info ctinfo) { u8 ct_state = OVS_CS_F_TRACKED; switch (ctinfo) { case IP_CT_ESTABLISHED_REPLY: case IP_CT_RELATED_REPLY: ct_state |= OVS_CS_F_REPLY_DIR; break; default: break; } switch (ctinfo) { case IP_CT_ESTABLISHED: case IP_CT_ESTABLISHED_REPLY: ct_state |= OVS_CS_F_ESTABLISHED; break; case IP_CT_RELATED: case IP_CT_RELATED_REPLY: ct_state |= OVS_CS_F_RELATED; break; case IP_CT_NEW: ct_state |= OVS_CS_F_NEW; break; default: break; } return ct_state; }

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static u32 ovs_ct_get_mark(const struct nf_conn *ct) { #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) return ct ? ct->mark : 0; #else return 0; #endif }

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/* Guard against conntrack labels max size shrinking below 128 bits. */ #if NF_CT_LABELS_MAX_SIZE < 16 #error NF_CT_LABELS_MAX_SIZE must be at least 16 bytes #endif
static void ovs_ct_get_labels(const struct nf_conn *ct, struct ovs_key_ct_labels *labels) { struct nf_conn_labels *cl = ct ? nf_ct_labels_find(ct) : NULL; if (cl) memcpy(labels, cl->bits, OVS_CT_LABELS_LEN); else memset(labels, 0, OVS_CT_LABELS_LEN); }

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static void __ovs_ct_update_key_orig_tp(struct sw_flow_key *key, const struct nf_conntrack_tuple *orig, u8 icmp_proto) { key->ct_orig_proto = orig->dst.protonum; if (orig->dst.protonum == icmp_proto) { key->ct.orig_tp.src = htons(orig->dst.u.icmp.type); key->ct.orig_tp.dst = htons(orig->dst.u.icmp.code); } else { key->ct.orig_tp.src = orig->src.u.all; key->ct.orig_tp.dst = orig->dst.u.all; } }

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static void __ovs_ct_update_key(struct sw_flow_key *key, u8 state, const struct nf_conntrack_zone *zone, const struct nf_conn *ct) { key->ct_state = state; key->ct_zone = zone->id; key->ct.mark = ovs_ct_get_mark(ct); ovs_ct_get_labels(ct, &key->ct.labels); if (ct) { const struct nf_conntrack_tuple *orig; /* Use the master if we have one. */ if (ct->master) ct = ct->master; orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; /* IP version must match with the master connection. */ if (key->eth.type == htons(ETH_P_IP) && nf_ct_l3num(ct) == NFPROTO_IPV4) { key->ipv4.ct_orig.src = orig->src.u3.ip; key->ipv4.ct_orig.dst = orig->dst.u3.ip; __ovs_ct_update_key_orig_tp(key, orig, IPPROTO_ICMP); return; } else if (key->eth.type == htons(ETH_P_IPV6) && !sw_flow_key_is_nd(key) && nf_ct_l3num(ct) == NFPROTO_IPV6) { key->ipv6.ct_orig.src = orig->src.u3.in6; key->ipv6.ct_orig.dst = orig->dst.u3.in6; __ovs_ct_update_key_orig_tp(key, orig, NEXTHDR_ICMP); return; } } /* Clear 'ct_orig_proto' to mark the non-existence of conntrack * original direction key fields. */ key->ct_orig_proto = 0; }

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/* Update 'key' based on skb->_nfct. If 'post_ct' is true, then OVS has * previously sent the packet to conntrack via the ct action. If * 'keep_nat_flags' is true, the existing NAT flags retained, else they are * initialized from the connection status. */
static void ovs_ct_update_key(const struct sk_buff *skb, const struct ovs_conntrack_info *info, struct sw_flow_key *key, bool post_ct, bool keep_nat_flags) { const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt; enum ip_conntrack_info ctinfo; struct nf_conn *ct; u8 state = 0; ct = nf_ct_get(skb, &ctinfo); if (ct) { state = ovs_ct_get_state(ctinfo); /* All unconfirmed entries are NEW connections. */ if (!nf_ct_is_confirmed(ct)) state |= OVS_CS_F_NEW; /* OVS persists the related flag for the duration of the * connection. */ if (ct->master) state |= OVS_CS_F_RELATED; if (keep_nat_flags) { state |= key->ct_state & OVS_CS_F_NAT_MASK; } else { if (ct->status & IPS_SRC_NAT) state |= OVS_CS_F_SRC_NAT; if (ct->status & IPS_DST_NAT) state |= OVS_CS_F_DST_NAT; } zone = nf_ct_zone(ct); } else if (post_ct) { state = OVS_CS_F_TRACKED | OVS_CS_F_INVALID; if (info) zone = &info->zone; } __ovs_ct_update_key(key, state, zone, ct); }

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/* This is called to initialize CT key fields possibly coming in from the local * stack. */
void ovs_ct_fill_key(const struct sk_buff *skb, struct sw_flow_key *key) { ovs_ct_update_key(skb, NULL, key, false, false); }

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#define IN6_ADDR_INITIALIZER(ADDR) \ { (ADDR).s6_addr32[0], (ADDR).s6_addr32[1], \ (ADDR).s6_addr32[2], (ADDR).s6_addr32[3] }
int ovs_ct_put_key(const struct sw_flow_key *swkey, const struct sw_flow_key *output, struct sk_buff *skb) { if (nla_put_u32(skb, OVS_KEY_ATTR_CT_STATE, output->ct_state)) return -EMSGSIZE; if (IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) && nla_put_u16(skb, OVS_KEY_ATTR_CT_ZONE, output->ct_zone)) return -EMSGSIZE; if (IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) && nla_put_u32(skb, OVS_KEY_ATTR_CT_MARK, output->ct.mark)) return -EMSGSIZE; if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) && nla_put(skb, OVS_KEY_ATTR_CT_LABELS, sizeof(output->ct.labels), &output->ct.labels)) return -EMSGSIZE; if (swkey->ct_orig_proto) { if (swkey->eth.type == htons(ETH_P_IP)) { struct ovs_key_ct_tuple_ipv4 orig = { output->ipv4.ct_orig.src, output->ipv4.ct_orig.dst, output->ct.orig_tp.src, output->ct.orig_tp.dst, output->ct_orig_proto, }; if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV4, sizeof(orig), &orig)) return -EMSGSIZE; } else if (swkey->eth.type == htons(ETH_P_IPV6)) { struct ovs_key_ct_tuple_ipv6 orig = { IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.src), IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.dst), output->ct.orig_tp.src, output->ct.orig_tp.dst, output->ct_orig_proto, }; if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV6, sizeof(orig), &orig)) return -EMSGSIZE; } } return 0; }

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static int ovs_ct_set_mark(struct nf_conn *ct, struct sw_flow_key *key, u32 ct_mark, u32 mask) { #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) u32 new_mark; new_mark = ct_mark | (ct->mark & ~(mask)); if (ct->mark != new_mark) { ct->mark = new_mark; if (nf_ct_is_confirmed(ct)) nf_conntrack_event_cache(IPCT_MARK, ct); key->ct.mark = new_mark; } return 0; #else return -ENOTSUPP; #endif }

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static struct nf_conn_labels *ovs_ct_get_conn_labels(struct nf_conn *ct) { struct nf_conn_labels *cl; cl = nf_ct_labels_find(ct); if (!cl) { nf_ct_labels_ext_add(ct); cl = nf_ct_labels_find(ct); } return cl; }

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/* Initialize labels for a new, yet to be committed conntrack entry. Note that * since the new connection is not yet confirmed, and thus no-one else has * access to it's labels, we simply write them over. */
static int ovs_ct_init_labels(struct nf_conn *ct, struct sw_flow_key *key, const struct ovs_key_ct_labels *labels, const struct ovs_key_ct_labels *mask) { struct nf_conn_labels *cl, *master_cl; bool have_mask = labels_nonzero(mask); /* Inherit master's labels to the related connection? */ master_cl = ct->master ? nf_ct_labels_find(ct->master) : NULL; if (!master_cl && !have_mask) return 0; /* Nothing to do. */ cl = ovs_ct_get_conn_labels(ct); if (!cl) return -ENOSPC; /* Inherit the master's labels, if any. */ if (master_cl) *cl = *master_cl; if (have_mask) { u32 *dst = (u32 *)cl->bits; int i; for (i = 0; i < OVS_CT_LABELS_LEN_32; i++) dst[i] = (dst[i] & ~mask->ct_labels_32[i]) | (labels->ct_labels_32[i] & mask->ct_labels_32[i]); } /* Labels are included in the IPCTNL_MSG_CT_NEW event only if the * IPCT_LABEL bit it set in the event cache. */ nf_conntrack_event_cache(IPCT_LABEL, ct); memcpy(&key->ct.labels, cl->bits, OVS_CT_LABELS_LEN); return 0; }

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static int ovs_ct_set_labels(struct nf_conn *ct, struct sw_flow_key *key, const struct ovs_key_ct_labels *labels, const struct ovs_key_ct_labels *mask) { struct nf_conn_labels *cl; int err; cl = ovs_ct_get_conn_labels(ct); if (!cl) return -ENOSPC; err = nf_connlabels_replace(ct, labels->ct_labels_32, mask->ct_labels_32, OVS_CT_LABELS_LEN_32); if (err) return err; memcpy(&key->ct.labels, cl->bits, OVS_CT_LABELS_LEN); return 0; }

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/* 'skb' should already be pulled to nh_ofs. */
static int ovs_ct_helper(struct sk_buff *skb, u16 proto) { const struct nf_conntrack_helper *helper; const struct nf_conn_help *help; enum ip_conntrack_info ctinfo; unsigned int protoff; struct nf_conn *ct; int err; ct = nf_ct_get(skb, &ctinfo); if (!ct || ctinfo == IP_CT_RELATED_REPLY) return NF_ACCEPT; help = nfct_help(ct); if (!help) return NF_ACCEPT; helper = rcu_dereference(help->helper); if (!helper) return NF_ACCEPT; switch (proto) { case NFPROTO_IPV4: protoff = ip_hdrlen(skb); break; case NFPROTO_IPV6: { u8 nexthdr = ipv6_hdr(skb)->nexthdr; __be16 frag_off; int ofs; ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off); if (ofs < 0 || (frag_off & htons(~0x7)) != 0) { pr_debug("proto header not found\n"); return NF_ACCEPT; } protoff = ofs; break; } default: WARN_ONCE(1, "helper invoked on non-IP family!"); return NF_DROP; } err = helper->help(skb, protoff, ct, ctinfo); if (err != NF_ACCEPT) return err; /* Adjust seqs after helper. This is needed due to some helpers (e.g., * FTP with NAT) adusting the TCP payload size when mangling IP * addresses and/or port numbers in the text-based control connection. */ if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) && !nf_ct_seq_adjust(skb, ct, ctinfo, protoff)) return NF_DROP; return NF_ACCEPT; }

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/* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero * value if 'skb' is freed. */
static int handle_fragments(struct net *net, struct sw_flow_key *key, u16 zone, struct sk_buff *skb) { struct ovs_skb_cb ovs_cb = *OVS_CB(skb); int err; if (key->eth.type == htons(ETH_P_IP)) { enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone; memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); err = ip_defrag(net, skb, user); if (err) return err; ovs_cb.mru = IPCB(skb)->frag_max_size; #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) } else if (key->eth.type == htons(ETH_P_IPV6)) { enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone; memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); err = nf_ct_frag6_gather(net, skb, user); if (err) { if (err != -EINPROGRESS) kfree_skb(skb); return err; } key->ip.proto = ipv6_hdr(skb)->nexthdr; ovs_cb.mru = IP6CB(skb)->frag_max_size; #endif } else { kfree_skb(skb); return -EPFNOSUPPORT; } key->ip.frag = OVS_FRAG_TYPE_NONE; skb_clear_hash(skb); skb->ignore_df = 1; *OVS_CB(skb) = ovs_cb; return 0; }

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static struct nf_conntrack_expect * ovs_ct_expect_find(struct net *net, const struct nf_conntrack_zone *zone, u16 proto, const struct sk_buff *skb) { struct nf_conntrack_tuple tuple; if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), proto, net, &tuple)) return NULL; return __nf_ct_expect_find(net, zone, &tuple); }

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/* This replicates logic from nf_conntrack_core.c that is not exported. */
static enum ip_conntrack_info ovs_ct_get_info(const struct nf_conntrack_tuple_hash *h) { const struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h); if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) return IP_CT_ESTABLISHED_REPLY; /* Once we've had two way comms, always ESTABLISHED. */ if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) return IP_CT_ESTABLISHED; if (test_bit(IPS_EXPECTED_BIT, &ct->status)) return IP_CT_RELATED; return IP_CT_NEW; }

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/* Find an existing connection which this packet belongs to without * re-attributing statistics or modifying the connection state. This allows an * skb->_nfct lost due to an upcall to be recovered during actions execution. * * Must be called with rcu_read_lock. * * On success, populates skb->_nfct and returns the connection. Returns NULL * if there is no existing entry. */
static struct nf_conn * ovs_ct_find_existing(struct net *net, const struct nf_conntrack_zone *zone, u8 l3num, struct sk_buff *skb, bool natted) { struct nf_conntrack_l3proto *l3proto; struct nf_conntrack_l4proto *l4proto; struct nf_conntrack_tuple tuple; struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; unsigned int dataoff; u8 protonum; l3proto = __nf_ct_l3proto_find(l3num); if (l3proto->get_l4proto(skb, skb_network_offset(skb), &dataoff, &protonum) <= 0) { pr_debug("ovs_ct_find_existing: Can't get protonum\n"); return NULL; } l4proto = __nf_ct_l4proto_find(l3num, protonum); if (!nf_ct_get_tuple(skb, skb_network_offset(skb), dataoff, l3num, protonum, net, &tuple, l3proto, l4proto)) { pr_debug("ovs_ct_find_existing: Can't get tuple\n"); return NULL; } /* Must invert the tuple if skb has been transformed by NAT. */ if (natted) { struct nf_conntrack_tuple inverse; if (!nf_ct_invert_tuple(&inverse, &tuple, l3proto, l4proto)) { pr_debug("ovs_ct_find_existing: Inversion failed!\n"); return NULL; } tuple = inverse; } /* look for tuple match */ h = nf_conntrack_find_get(net, zone, &tuple); if (!h) return NULL; /* Not found. */ ct = nf_ct_tuplehash_to_ctrack(h); /* Inverted packet tuple matches the reverse direction conntrack tuple, * select the other tuplehash to get the right 'ctinfo' bits for this * packet. */ if (natted) h = &ct->tuplehash[!h->tuple.dst.dir]; nf_ct_set(skb, ct, ovs_ct_get_info(h)); return ct; }

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/* Determine whether skb->_nfct is equal to the result of conntrack lookup. */
static bool skb_nfct_cached(struct net *net, const struct sw_flow_key *key, const struct ovs_conntrack_info *info, struct sk_buff *skb) { enum ip_conntrack_info ctinfo; struct nf_conn *ct; ct = nf_ct_get(skb, &ctinfo); /* If no ct, check if we have evidence that an existing conntrack entry * might be found for this skb. This happens when we lose a skb->_nfct * due to an upcall. If the connection was not confirmed, it is not * cached and needs to be run through conntrack again. */ if (!ct && key->ct_state & OVS_CS_F_TRACKED && !(key->ct_state & OVS_CS_F_INVALID) && key->ct_zone == info->zone.id) { ct = ovs_ct_find_existing(net, &info->zone, info->family, skb, !!(key->ct_state & OVS_CS_F_NAT_MASK)); if (ct) nf_ct_get(skb, &ctinfo); } if (!ct) return false; if (!net_eq(net, read_pnet(&ct->ct_net))) return false; if (!nf_ct_zone_equal_any(info->ct, nf_ct_zone(ct))) return false; if (info->helper) { struct nf_conn_help *help; help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER); if (help && rcu_access_pointer(help->helper) != info->helper) return false; } /* Force conntrack entry direction to the current packet? */ if (info->force && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) { /* Delete the conntrack entry if confirmed, else just release * the reference. */ if (nf_ct_is_confirmed(ct)) nf_ct_delete(ct, 0, 0); nf_conntrack_put(&ct->ct_general); nf_ct_set(skb, NULL, 0); return false; } return true; }

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#ifdef CONFIG_NF_NAT_NEEDED /* Modelled after nf_nat_ipv[46]_fn(). * range is only used for new, uninitialized NAT state. * Returns either NF_ACCEPT or NF_DROP. */
static int ovs_ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info ctinfo, const struct nf_nat_range *range, enum nf_nat_manip_type maniptype) { int hooknum, nh_off, err = NF_ACCEPT; nh_off = skb_network_offset(skb); skb_pull_rcsum(skb, nh_off); /* See HOOK2MANIP(). */ if (maniptype == NF_NAT_MANIP_SRC) hooknum = NF_INET_LOCAL_IN; /* Source NAT */ else hooknum = NF_INET_LOCAL_OUT; /* Destination NAT */ switch (ctinfo) { case IP_CT_RELATED: case IP_CT_RELATED_REPLY: if (IS_ENABLED(CONFIG_NF_NAT_IPV4) && skb->protocol == htons(ETH_P_IP) && ip_hdr(skb)->protocol == IPPROTO_ICMP) { if (!nf_nat_icmp_reply_translation