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netfilter: xt_mangle: only check verdict part of return value 

These checks assume that the caller only returns NF_DROP without
any errno embedded in the upper bits.

This is fine right now, but followup patches will start to propagate
such errors to allow kfree_skb_drop_reason() in the called functions,
those would then indicate 'errno << 8 | NF_STOLEN'.

To not break things we have to mask those parts out.

Signed-off-by: Florian Westphal <fw@strlen.de>
This commit is contained in:
Florian Westphal 2023-10-11 09:59:34 +02:00
parent a0a8602247
commit e15e502710
2 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
net/ipv4/netfilter/iptable_mangle.c
View File

@ -36,12 +36,12 @@ static const struct xt_table packet_mangler = {
static unsigned int
ipt_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
{
unsigned int ret;
unsigned int ret, verdict;
const struct iphdr *iph;
u_int8_t tos;
__be32 saddr, daddr;
u_int32_t mark;
u32 mark;
int err;
u8 tos;
/* Save things which could affect route */
mark = skb->mark;
@ -51,8 +51,9 @@ ipt_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *stat
tos = iph->tos;
ret = ipt_do_table(priv, skb, state);
verdict = ret & NF_VERDICT_MASK;
/* Reroute for ANY change. */
if (ret != NF_DROP && ret != NF_STOLEN) {
if (verdict != NF_DROP && verdict != NF_STOLEN) {
iph = ip_hdr(skb);
if (iph->saddr != saddr ||

9
net/ipv6/netfilter/ip6table_mangle.c
View File

@ -31,10 +31,10 @@ static const struct xt_table packet_mangler = {
static unsigned int
ip6t_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
{
unsigned int ret;
struct in6_addr saddr, daddr;
u_int8_t hop_limit;
u_int32_t flowlabel, mark;
unsigned int ret, verdict;
u32 flowlabel, mark;
u8 hop_limit;
int err;
/* save source/dest address, mark, hoplimit, flowlabel, priority, */
@ -47,8 +47,9 @@ ip6t_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *sta
flowlabel = *((u_int32_t *)ipv6_hdr(skb));
ret = ip6t_do_table(priv, skb, state);
verdict = ret & NF_VERDICT_MASK;
if (ret != NF_DROP && ret != NF_STOLEN &&
if (verdict != NF_DROP && verdict != NF_STOLEN &&
(!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
!ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
skb->mark != mark ||