also start splitting psd_match into two functions, one
to do initial sanity checking and header retrieval, one
to do the actual work.
---
extensions/xt_psd.c | 96 ++++++++++++++++++++++++++++----------------------
1 files changed, 54 insertions(+), 42 deletions(-)
diff --git a/extensions/xt_psd.c b/extensions/xt_psd.c
index 09251e7..9c52426 100644
--- a/extensions/xt_psd.c
+++ b/extensions/xt_psd.c
@@ -209,52 +209,36 @@ static void remove_oldest(struct host **head, struct host *curr)
ht_unlink(head, last);
}
+static void *
+get_header_pointer4(const struct sk_buff *skb, unsigned int thoff, void *mem)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ int hdrlen;
+
+ switch (iph->protocol) {
+ case IPPROTO_TCP:
+ hdrlen = sizeof(struct tcphdr);
+ break;
+ case IPPROTO_UDP:
+ case IPPROTO_UDPLITE:
+ hdrlen = sizeof(struct udphdr);
+ break;
+ default:
+ return NULL;
+ }
+
+ return skb_header_pointer(skb, thoff, hdrlen, mem);
+}
+
static bool
-xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
+handle_packet4(const struct iphdr *iph, const struct tcphdr *tcph,
+ const struct xt_psd_info *psdinfo)
{
- const struct iphdr *iph;
- const struct tcphdr *tcph = NULL;
- union {
- struct tcphdr tcph;
- struct udphdr udph;
- } _buf;
- u_int8_t proto;
unsigned long now;
struct host *curr, *last = NULL, **head;
struct host4 *curr4;
int count = 0;
unsigned int hash;
- /* Parameters from userspace */
- const struct xt_psd_info *psdinfo = match->matchinfo;
-
- iph = ip_hdr(pskb);
- if (iph->frag_off & htons(IP_OFFSET)) {
- pr_debug("sanity check failed\n");
- return false;
- }
-
- proto = iph->protocol;
- /* We're using IP address 0.0.0.0 for a special purpose here, so don't let
- * them spoof us. [DHCP needs this feature - HW] */
- if (iph->saddr == 0) {
- pr_debug("spoofed source address (0.0.0.0)\n");
- return false;
- }
-
- if (proto == IPPROTO_TCP) {
- tcph = skb_header_pointer(pskb, match->thoff,
- sizeof(_buf.tcph), &_buf.tcph);
- if (tcph == NULL)
- return false;
- } else if (proto == IPPROTO_UDP || proto == IPPROTO_UDPLITE) {
- tcph = skb_header_pointer(pskb, match->thoff,
- sizeof(_buf.udph), &_buf.udph);
- if (tcph == NULL)
- return false;
- } else {
- pr_debug("protocol not supported\n");
- return false;
- }
now = jiffies;
hash = hashfunc(iph->saddr);
@@ -275,7 +259,7 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
if (curr != NULL) {
/* We know this address, and the entry isn't too old. Update it. */
if (entry_is_recent(curr, psdinfo->delay_threshold, now)) {
- if (is_portscan(curr, psdinfo, tcph, proto))
+ if (is_portscan(curr, psdinfo, tcph, iph->protocol))
goto out_match;
goto out_no_match;
}
@@ -289,7 +273,7 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
}
/* We don't need an ACK from a new source address */
- if (proto == IPPROTO_TCP && tcph->ack)
+ if (iph->protocol == IPPROTO_TCP && tcph->ack)
goto out_no_match;
/* Got too many source addresses with the same hash value? Then remove the
@@ -322,7 +306,7 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
curr->count = 1;
curr->weight = get_port_weight(psdinfo, tcph->dest);
curr->ports[0].number = tcph->dest;
- curr->ports[0].proto = proto;
+ curr->ports[0].proto = iph->protocol;
out_no_match:
spin_unlock(&state.lock);
@@ -333,6 +317,34 @@ out_match:
return true;
}
+static bool
+xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
+{
+ struct iphdr *iph = ip_hdr(pskb);
+ struct tcphdr _tcph;
+ struct tcphdr *tcph;
+ /* Parameters from userspace */
+ const struct xt_psd_info *psdinfo = match->matchinfo;
+
+ if (iph->frag_off & htons(IP_OFFSET)) {
+ pr_debug("sanity check failed\n");
+ return false;
+ }
+
+ /* We're using IP address 0.0.0.0 for a special purpose here, so don't let
+ * them spoof us. [DHCP needs this feature - HW] */
+ if (iph->saddr == 0) {
+ pr_debug("spoofed source address (0.0.0.0)\n");
+ return false;
+ }
+
+ tcph = get_header_pointer4(pskb, match->thoff, &_tcph);
+ if (tcph == NULL)
+ return false;
+
+ return handle_packet4(iph, tcph, psdinfo);
+}
+
static int psd_mt_check(const struct xt_mtchk_param *par)
{
const struct xt_psd_info *info = par->matchinfo;
--
1.7.8.6
--
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