/* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
static bool tcp_error(const struct tcphdr *th,
struct sk_buff *skb,
unsigned int dataoff,
const struct nf_hook_state *state)
{
unsigned int tcplen = skb->len - dataoff;
u8 tcpflags;
/* Not whole TCP header or malformed packet */
if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
tcp_error_log(skb, state, "truncated packet");
return true;
}
/* Checksum invalid? Ignore.
* We skip checking packets on the outgoing path
* because the checksum is assumed to be correct.
*/
/* FIXME: Source route IP option packets --RR */
if (state->net->ct.sysctl_checksum &&
state->hook == NF_INET_PRE_ROUTING &&
nf_checksum(skb, state->hook, dataoff, IPPROTO_TCP, state->pf)) {
tcp_error_log(skb, state, "bad checksum");
return true;
}
/* Check TCP flags. */
tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
if (!tcp_valid_flags[tcpflags]) {
tcp_error_log(skb, state, "invalid tcp flag combination");
return true;
}
return false;
}
/* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
static int tcp_error(struct net *net,
struct sk_buff *skb,
unsigned int dataoff,
enum ip_conntrack_info *ctinfo,
u_int8_t pf,
unsigned int hooknum)
{
const struct tcphdr *th;
struct tcphdr _tcph;
unsigned int tcplen = skb->len - dataoff;
u_int8_t tcpflags;
/* Smaller that minimal TCP header? */
th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
if (th == NULL) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: short packet ");
return -NF_ACCEPT;
}
/* Not whole TCP header or malformed packet */
if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: truncated/malformed packet ");
return -NF_ACCEPT;
}
/* Checksum invalid? Ignore.
* We skip checking packets on the outgoing path
* because the checksum is assumed to be correct.
*/
/* FIXME: Source route IP option packets --RR */
if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: bad TCP checksum ");
return -NF_ACCEPT;
}
/* Check TCP flags. */
tcpflags = (((u_int8_t *)th)[13] & ~(TH_ECE|TH_CWR|TH_PUSH));
if (!tcp_valid_flags[tcpflags]) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: invalid TCP flag combination ");
return -NF_ACCEPT;
}
return NF_ACCEPT;
}
static int udp_error(struct sk_buff *skb, unsigned int dataoff,
enum ip_conntrack_info *ctinfo,
int pf,
unsigned int hooknum)
{
unsigned int udplen = skb->len - dataoff;
const struct udphdr *hdr;
struct udphdr _hdr;
/* Header is too small? */
hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
if (hdr == NULL) {
if (LOG_INVALID(IPPROTO_UDP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: short packet ");
return -NF_ACCEPT;
}
/* Truncated/malformed packets */
if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
if (LOG_INVALID(IPPROTO_UDP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: truncated/malformed packet ");
return -NF_ACCEPT;
}
#if defined(CONFIG_BCM_NAT) || defined(CONFIG_BCM_NAT_MODULE)
if (nf_conntrack_fastnat)
return NF_ACCEPT;
#endif
/* Packet with no checksum */
if (!hdr->check)
return NF_ACCEPT;
/* Checksum invalid? Ignore.
* We skip checking packets on the outgoing path
* because the checksum is assumed to be correct.
* FIXME: Source route IP option packets --RR */
if (nf_conntrack_checksum &&
((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
(pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) &&
nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
if (LOG_INVALID(IPPROTO_UDP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: bad UDP checksum ");
return -NF_ACCEPT;
}
return NF_ACCEPT;
}
static int tcp_error(struct net *net, struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
enum ip_conntrack_info *ctinfo,
u_int8_t pf,
unsigned int hooknum)
{
const struct tcphdr *th;
struct tcphdr _tcph;
unsigned int tcplen = skb->len - dataoff;
u_int8_t tcpflags;
th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
if (th == NULL) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: short packet ");
return -NF_ACCEPT;
}
if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: truncated/malformed packet ");
return -NF_ACCEPT;
}
if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: bad TCP checksum ");
return -NF_ACCEPT;
}
tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
if (!tcp_valid_flags[tcpflags]) {
if (LOG_INVALID(net, IPPROTO_TCP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_tcp: invalid TCP flag combination ");
return -NF_ACCEPT;
}
return NF_ACCEPT;
}
static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
unsigned int dataoff,
u_int8_t pf,
unsigned int hooknum)
{
unsigned int udplen = skb->len - dataoff;
const struct udphdr *hdr;
struct udphdr _hdr;
/* Header is too small? */
hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
if (hdr == NULL) {
if (LOG_INVALID(net, IPPROTO_UDP))
nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: short packet ");
return -NF_ACCEPT;
}
/* Truncated/malformed packets */
if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
if (LOG_INVALID(net, IPPROTO_UDP))
nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: truncated/malformed packet ");
return -NF_ACCEPT;
}
/* Packet with no checksum */
if (!hdr->check)
return NF_ACCEPT;
/* Checksum invalid? Ignore.
* We skip checking packets on the outgoing path
* because the checksum is assumed to be correct.
* FIXME: Source route IP option packets --RR */
if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
if (LOG_INVALID(net, IPPROTO_UDP))
nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: bad UDP checksum ");
return -NF_ACCEPT;
}
return NF_ACCEPT;
}
/* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */
static int tcp_error(struct net *net, struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
u_int8_t pf,
unsigned int hooknum)
{
const struct tcphdr *th;
struct tcphdr _tcph;
unsigned int tcplen = skb->len - dataoff;
u_int8_t tcpflags;
/* Smaller that minimal TCP header? */
th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
if (th == NULL) {
tcp_error_log(skb, net, pf, "short packet");
return -NF_ACCEPT;
}
/* Not whole TCP header or malformed packet */
if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) {
tcp_error_log(skb, net, pf, "truncated packet");
return -NF_ACCEPT;
}
/* Checksum invalid? Ignore.
* We skip checking packets on the outgoing path
* because the checksum is assumed to be correct.
*/
/* FIXME: Source route IP option packets --RR */
if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
nf_checksum(skb, hooknum, dataoff, IPPROTO_TCP, pf)) {
tcp_error_log(skb, net, pf, "bad checksum");
return -NF_ACCEPT;
}
/* Check TCP flags. */
tcpflags = (tcp_flag_byte(th) & ~(TCPHDR_ECE|TCPHDR_CWR|TCPHDR_PSH));
if (!tcp_valid_flags[tcpflags]) {
tcp_error_log(skb, net, pf, "invalid tcp flag combination");
return -NF_ACCEPT;
}
return NF_ACCEPT;
}
static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
unsigned int dataoff, enum ip_conntrack_info *ctinfo,
u_int8_t pf,
unsigned int hooknum)
{
unsigned int udplen = skb->len - dataoff;
const struct udphdr *hdr;
struct udphdr _hdr;
/* */
hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
if (hdr == NULL) {
if (LOG_INVALID(net, IPPROTO_UDP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: short packet ");
return -NF_ACCEPT;
}
/* */
if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
if (LOG_INVALID(net, IPPROTO_UDP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: truncated/malformed packet ");
return -NF_ACCEPT;
}
/* */
if (!hdr->check)
return NF_ACCEPT;
/*
*/
if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
if (LOG_INVALID(net, IPPROTO_UDP))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udp: bad UDP checksum ");
return -NF_ACCEPT;
}
return NF_ACCEPT;
}
static bool udp_error(struct sk_buff *skb,
unsigned int dataoff,
const struct nf_hook_state *state)
{
unsigned int udplen = skb->len - dataoff;
const struct udphdr *hdr;
struct udphdr _hdr;
/* Header is too small? */
hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
if (!hdr) {
udp_error_log(skb, state, "short packet");
return true;
}
/* Truncated/malformed packets */
if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
udp_error_log(skb, state, "truncated/malformed packet");
return true;
}
/* Packet with no checksum */
if (!hdr->check)
return false;
/* Checksum invalid? Ignore.
* We skip checking packets on the outgoing path
* because the checksum is assumed to be correct.
* FIXME: Source route IP option packets --RR */
if (state->hook == NF_INET_PRE_ROUTING &&
state->net->ct.sysctl_checksum &&
nf_checksum(skb, state->hook, dataoff, IPPROTO_UDP, state->pf)) {
udp_error_log(skb, state, "bad checksum");
return true;
}
return false;
}
