From 6816d931cab009024b68c11c4cf752f8bf9a1e32 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 29 Jun 2018 07:46:47 +0200 Subject: netfilter: conntrack: remove get_l4proto indirection from l3 protocol trackers Handle it in the core instead. ipv6_skip_exthdr() is built-in even if ipv6 is a module, i.e. this doesn't create an ipv6 dependency. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_core.c | 108 +++++++++++++++++++++++++++++++------- 1 file changed, 88 insertions(+), 20 deletions(-) (limited to 'net/netfilter/nf_conntrack_core.c') diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 14c040805b32..0674c6e5bfed 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -37,7 +37,6 @@ #include #include -#include #include #include #include @@ -55,6 +54,7 @@ #include #include #include +#include #include "nf_internals.h" @@ -273,21 +273,94 @@ nf_ct_get_tuple(const struct sk_buff *skb, return l4proto->pkt_to_tuple(skb, dataoff, net, tuple); } +static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, + u_int8_t *protonum) +{ + int dataoff = -1; +#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV4) + const struct iphdr *iph; + struct iphdr _iph; + + iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph); + if (!iph) + return -1; + + /* Conntrack defragments packets, we might still see fragments + * inside ICMP packets though. + */ + if (iph->frag_off & htons(IP_OFFSET)) + return -1; + + dataoff = nhoff + (iph->ihl << 2); + *protonum = iph->protocol; + + /* Check bogus IP headers */ + if (dataoff > skb->len) { + pr_debug("bogus IPv4 packet: nhoff %u, ihl %u, skblen %u\n", + nhoff, iph->ihl << 2, skb->len); + return -1; + } +#endif + return dataoff; +} + +static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, + u8 *protonum) +{ + int protoff = -1; +#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6) + unsigned int extoff = nhoff + sizeof(struct ipv6hdr); + __be16 frag_off; + u8 nexthdr; + + if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr), + &nexthdr, sizeof(nexthdr)) != 0) { + pr_debug("can't get nexthdr\n"); + return -1; + } + protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off); + /* + * (protoff == skb->len) means the packet has not data, just + * IPv6 and possibly extensions headers, but it is tracked anyway + */ + if (protoff < 0 || (frag_off & htons(~0x7)) != 0) { + pr_debug("can't find proto in pkt\n"); + return -1; + } + + *protonum = nexthdr; +#endif + return protoff; +} + +static int get_l4proto(const struct sk_buff *skb, + unsigned int nhoff, u8 pf, u8 *l4num) +{ + switch (pf) { + case NFPROTO_IPV4: + return ipv4_get_l4proto(skb, nhoff, l4num); + case NFPROTO_IPV6: + return ipv6_get_l4proto(skb, nhoff, l4num); + default: + *l4num = 0; + break; + } + return -1; +} + bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff, u_int16_t l3num, struct net *net, struct nf_conntrack_tuple *tuple) { - const struct nf_conntrack_l3proto *l3proto; const struct nf_conntrack_l4proto *l4proto; - unsigned int protoff; - u_int8_t protonum; + u8 protonum; + int protoff; int ret; rcu_read_lock(); - l3proto = __nf_ct_l3proto_find(l3num); - ret = l3proto->get_l4proto(skb, nhoff, &protoff, &protonum); - if (ret != NF_ACCEPT) { + protoff = get_l4proto(skb, nhoff, l3num, &protonum); + if (protoff <= 0) { rcu_read_unlock(); return false; } @@ -1397,14 +1470,12 @@ unsigned int nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, struct sk_buff *skb) { - const struct nf_conntrack_l3proto *l3proto; const struct nf_conntrack_l4proto *l4proto; struct nf_conn *ct, *tmpl; enum ip_conntrack_info ctinfo; unsigned int *timeouts; - unsigned int dataoff; u_int8_t protonum; - int ret; + int dataoff, ret; tmpl = nf_ct_get(skb, &ctinfo); if (tmpl || ctinfo == IP_CT_UNTRACKED) { @@ -1418,14 +1489,12 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, } /* rcu_read_lock()ed by nf_hook_thresh */ - l3proto = __nf_ct_l3proto_find(pf); - ret = l3proto->get_l4proto(skb, skb_network_offset(skb), - &dataoff, &protonum); - if (ret <= 0) { + dataoff = get_l4proto(skb, skb_network_offset(skb), pf, &protonum); + if (dataoff <= 0) { pr_debug("not prepared to track yet or error occurred\n"); NF_CT_STAT_INC_ATOMIC(net, error); NF_CT_STAT_INC_ATOMIC(net, invalid); - ret = -ret; + ret = NF_ACCEPT; goto out; } @@ -1641,14 +1710,14 @@ static void nf_conntrack_attach(struct sk_buff *nskb, const struct sk_buff *skb) static int nf_conntrack_update(struct net *net, struct sk_buff *skb) { - const struct nf_conntrack_l3proto *l3proto; const struct nf_conntrack_l4proto *l4proto; struct nf_conntrack_tuple_hash *h; struct nf_conntrack_tuple tuple; enum ip_conntrack_info ctinfo; struct nf_nat_hook *nat_hook; - unsigned int dataoff, status; + unsigned int status; struct nf_conn *ct; + int dataoff; u16 l3num; u8 l4num; @@ -1657,10 +1726,9 @@ static int nf_conntrack_update(struct net *net, struct sk_buff *skb) return 0; l3num = nf_ct_l3num(ct); - l3proto = nf_ct_l3proto_find_get(l3num); - if (l3proto->get_l4proto(skb, skb_network_offset(skb), &dataoff, - &l4num) <= 0) + dataoff = get_l4proto(skb, skb_network_offset(skb), l3num, &l4num); + if (dataoff <= 0) return -1; l4proto = nf_ct_l4proto_find_get(l3num, l4num); -- cgit v1.2.3-55-g7522