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netfilter: introduce nft_set_pktinfo_{ipv4, ipv6}_validate()

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These functions are extracted from the netdev family, they initialize
the pktinfo structure and validate that the IPv4 and IPv6 headers are
well-formed given that these functions are called from a path where
layer 3 sanitization did not happen yet.

These functions are placed in include/net/netfilter/nf_tables_ipv{4,6}.h
so they can be reused by a follow up patch to use them from the bridge
family too.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2016-09-09 12:42:51 +02:00
parent 8df9e32e7e
commit ddc8b6027a
3 changed files with 93 additions and 77 deletions
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42
include/net/netfilter/nf_tables_ipv4.h
View File

@ -20,6 +20,48 @@ nft_set_pktinfo_ipv4(struct nft_pktinfo *pkt,
pkt->xt.fragoff = ntohs(ip->frag_off) & IP_OFFSET;
}
static inline int
__nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
struct iphdr *iph, _iph;
u32 len, thoff;
iph = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*iph),
&_iph);
if (!iph)
return -1;
iph = ip_hdr(skb);
if (iph->ihl < 5 || iph->version != 4)
return -1;
len = ntohs(iph->tot_len);
thoff = iph->ihl * 4;
if (skb->len < len)
return -1;
else if (len < thoff)
return -1;
pkt->tprot_set = true;
pkt->tprot = iph->protocol;
pkt->xt.thoff = thoff;
pkt->xt.fragoff = ntohs(iph->frag_off) & IP_OFFSET;
return 0;
}
static inline void
nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
nft_set_pktinfo(pkt, skb, state);
if (__nft_set_pktinfo_ipv4_validate(pkt, skb, state) < 0)
nft_set_pktinfo_proto_unspec(pkt, skb);
}
extern struct nft_af_info nft_af_ipv4;
#endif

49
include/net/netfilter/nf_tables_ipv6.h
View File

@ -28,6 +28,55 @@ nft_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
return 0;
}
static inline int
__nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
#if IS_ENABLED(CONFIG_IPV6)
struct ipv6hdr *ip6h, _ip6h;
unsigned int thoff = 0;
unsigned short frag_off;
int protohdr;
u32 pkt_len;
ip6h = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*ip6h),
&_ip6h);
if (!ip6h)
return -1;
if (ip6h->version != 6)
return -1;
pkt_len = ntohs(ip6h->payload_len);
if (pkt_len + sizeof(*ip6h) > skb->len)
return -1;
protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, NULL);
if (protohdr < 0)
return -1;
pkt->tprot_set = true;
pkt->tprot = protohdr;
pkt->xt.thoff = thoff;
pkt->xt.fragoff = frag_off;
return 0;
#else
return -1;
#endif
}
static inline void
nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
nft_set_pktinfo(pkt, skb, state);
if (__nft_set_pktinfo_ipv6_validate(pkt, skb, state) < 0)
nft_set_pktinfo_proto_unspec(pkt, skb);
}
extern struct nft_af_info nft_af_ipv6;
#endif

79
net/netfilter/nf_tables_netdev.c
View File

@ -15,81 +15,6 @@
#include <net/netfilter/nf_tables_ipv4.h>
#include <net/netfilter/nf_tables_ipv6.h>
static inline void
nft_netdev_set_pktinfo_ipv4(struct nft_pktinfo *pkt,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
struct iphdr *iph, _iph;
u32 len, thoff;
nft_set_pktinfo(pkt, skb, state);
iph = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*iph),
&_iph);
if (!iph)
return;
iph = ip_hdr(skb);
if (iph->ihl < 5 || iph->version != 4)
return;
len = ntohs(iph->tot_len);
thoff = iph->ihl * 4;
if (skb->len < len)
return;
else if (len < thoff)
return;
pkt->tprot_set = true;
pkt->tprot = iph->protocol;
pkt->xt.thoff = thoff;
pkt->xt.fragoff = ntohs(iph->frag_off) & IP_OFFSET;
}
static inline void
__nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
#if IS_ENABLED(CONFIG_IPV6)
struct ipv6hdr *ip6h, _ip6h;
unsigned int thoff = 0;
unsigned short frag_off;
int protohdr;
u32 pkt_len;
ip6h = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*ip6h),
&_ip6h);
if (!ip6h)
return;
if (ip6h->version != 6)
return;
pkt_len = ntohs(ip6h->payload_len);
if (pkt_len + sizeof(*ip6h) > skb->len)
return;
protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, NULL);
if (protohdr < 0)
return;
pkt->tprot_set = true;
pkt->tprot = protohdr;
pkt->xt.thoff = thoff;
pkt->xt.fragoff = frag_off;
#endif
}
static inline void nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
nft_set_pktinfo(pkt, skb, state);
__nft_netdev_set_pktinfo_ipv6(pkt, skb, state);
}
static unsigned int
nft_do_chain_netdev(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state)
@ -98,10 +23,10 @@ nft_do_chain_netdev(void *priv, struct sk_buff *skb,
switch (skb->protocol) {
case htons(ETH_P_IP):
nft_netdev_set_pktinfo_ipv4(&pkt, skb, state);
nft_set_pktinfo_ipv4_validate(&pkt, skb, state);
break;
case htons(ETH_P_IPV6):
nft_netdev_set_pktinfo_ipv6(&pkt, skb, state);
nft_set_pktinfo_ipv6_validate(&pkt, skb, state);
break;
default:
nft_set_pktinfo_unspec(&pkt, skb, state);