lkml.org 
[lkml]   [2001]   [Nov]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRe: Fw: Networking: repeatable oops in 2.4.15-pre2
Date
In message <200111101857.VAA17220@ms2.inr.ac.ru> you write:
> A. Paul, look into your own code doing the same thing which you wrote before.
> Seems, you have lost the skill of copying skbs owned by sockets.

Argh... that explains the crashes, of course. You have a good memory!

> Actually, skbs owned by sockets should not be copied at all, if
> mangle does not involve change of data.

The NAT code is special: it will always mangle packet the same way, so
it doesn't *REALLY* matter if we mangle the original packet for local
output (if we change IP headers in different ways for retransmission
of the same packet, we would have much bigger problems).

> B. It is very strange that a copy happened in local output path.
> The problem which was supposed to be cured by this was at input.

My solution was too generic: *any* cloned skb was copied. Repairing
is simple.

Does this work for everyone? Particularly while running tcpdump?
Rusty.
--
Premature optmztion is rt of all evl. --DK

diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.4.14-official/net/ipv4/netfilter/ip_fw_compat.c working-2.4.13-uml-proc/net/ipv4/netfilter/ip_fw_compat.c
--- linux-2.4.14-official/net/ipv4/netfilter/ip_fw_compat.c Sun Apr 29 06:17:11 2001
+++ working-2.4.13-uml-proc/net/ipv4/netfilter/ip_fw_compat.c Tue Nov 13 20:58:33 2001
@@ -78,11 +78,21 @@
{
int ret = FW_BLOCK;
u_int16_t redirpt;
+ struct sk_buff *nskb;

/* Assume worse case: any hook could change packet */
(*pskb)->nfcache |= NFC_UNKNOWN | NFC_ALTERED;
if ((*pskb)->ip_summed == CHECKSUM_HW)
(*pskb)->ip_summed = CHECKSUM_NONE;
+
+ /* Firewall rules can alter TOS: raw socket (tcpdump) may have
+ clone of incoming skb: don't disturb it --RR */
+ if (skb_cloned(*pskb) && !(*pskb)->sk) {
+ struct sk_buff *nskb = skb_copy(*pskb, GFP_ATOMIC);
+ if (!nskb)
+ return NF_DROP;
+ *pskb = nskb;
+ }

switch (hooknum) {
case NF_IP_PRE_ROUTING:
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.4.14-official/net/ipv4/netfilter/ip_nat_core.c working-2.4.13-uml-proc/net/ipv4/netfilter/ip_nat_core.c
--- linux-2.4.14-official/net/ipv4/netfilter/ip_nat_core.c Mon May 28 12:43:00 2001
+++ working-2.4.13-uml-proc/net/ipv4/netfilter/ip_nat_core.c Tue Nov 13 20:57:56 2001
@@ -734,6 +734,17 @@
synchronize_bh()) can vanish. */
READ_LOCK(&ip_nat_lock);
for (i = 0; i < info->num_manips; i++) {
+ /* raw socket (tcpdump) may have clone of incoming
+ skb: don't disturb it --RR */
+ if (skb_cloned(*pskb) && !(*pskb)->sk) {
+ struct sk_buff *nskb = skb_copy(*pskb, GFP_ATOMIC);
+ if (!nskb) {
+ READ_UNLOCK(&ip_nat_lock);
+ return NF_DROP;
+ }
+ *pskb = nskb;
+ }
+
if (info->manips[i].direction == dir
&& info->manips[i].hooknum == hooknum) {
DEBUGP("Mangling %p: %s to %u.%u.%u.%u %u\n",
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.4.14-official/net/ipv4/netfilter/ipt_TCPMSS.c working-2.4.13-uml-proc/net/ipv4/netfilter/ipt_TCPMSS.c
--- linux-2.4.14-official/net/ipv4/netfilter/ipt_TCPMSS.c Thu Oct 25 11:29:50 2001
+++ working-2.4.13-uml-proc/net/ipv4/netfilter/ipt_TCPMSS.c Tue Nov 13 20:59:42 2001
@@ -44,11 +44,22 @@
{
const struct ipt_tcpmss_info *tcpmssinfo = targinfo;
struct tcphdr *tcph;
- struct iphdr *iph = (*pskb)->nh.iph;
+ struct iphdr *iph;
u_int16_t tcplen, newtotlen, oldval, newmss;
unsigned int i;
u_int8_t *opt;
+ struct sk_buff *nskb;

+ /* raw socket (tcpdump) may have clone of incoming skb: don't
+ disturb it --RR */
+ if (skb_cloned(*pskb) && !(*pskb)->sk) {
+ struct sk_buff *nskb = skb_copy(*pskb, GFP_ATOMIC);
+ if (!nskb)
+ return NF_DROP;
+ *pskb = nskb;
+ }
+
+ iph = (*pskb)->nh.iph;
tcplen = (*pskb)->len - iph->ihl*4;

tcph = (void *)iph + iph->ihl*4;
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.4.14-official/net/ipv4/netfilter/ipt_TOS.c working-2.4.13-uml-proc/net/ipv4/netfilter/ipt_TOS.c
--- linux-2.4.14-official/net/ipv4/netfilter/ipt_TOS.c Thu Oct 25 11:29:50 2001
+++ working-2.4.13-uml-proc/net/ipv4/netfilter/ipt_TOS.c Tue Nov 13 21:02:20 2001
@@ -19,7 +19,18 @@
const struct ipt_tos_target_info *tosinfo = targinfo;

if ((iph->tos & IPTOS_TOS_MASK) != tosinfo->tos) {
+ struct sk_buff *nskb;
u_int16_t diffs[2];
+
+ /* raw socket (tcpdump) may have clone of incoming
+ skb: don't disturb it --RR */
+ if (skb_cloned(*pskb) && !(*pskb)->sk) {
+ struct sk_buff *nskb = skb_copy(*pskb, GFP_ATOMIC);
+ if (!nskb)
+ return NF_DROP;
+ *pskb = nskb;
+ iph = (*pskb)->nh.iph;
+ }

diffs[0] = htons(iph->tos) ^ 0xFFFF;
iph->tos = (iph->tos & IPTOS_PREC_MASK) | tosinfo->tos;
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 13:13    [W:0.050 / U:4.456 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site