Propagate routing errors from ip_route_me_harder() when dropping a packet
using NF_DROP_ERR(). This makes userspace get the proper error instead of
EPERM for everything.
Example:
# ip r a unreachable default table 100
# ip ru add fwmark 0x1 lookup 100
# iptables -t mangle -A OUTPUT -d 8.8.8.8 -j MARK --set-mark 0x1
Current behaviour:
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
New behaviour:
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
net/ipv4/netfilter.c | 8 ++++----
net/ipv4/netfilter/iptable_mangle.c | 9 ++++++---
net/ipv4/netfilter/iptable_nat.c | 6 ++++--
3 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index 4c0cf63..8b201e8 100644
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c
@@ -40,14 +40,14 @@ int ip_route_me_harder(struct sk_buff *skb, unsigned int addr_type)
fl4.flowi4_flags = flags;
rt = ip_route_output_key(net, &fl4);
if (IS_ERR(rt))
- return -1;
+ return PTR_ERR(rt);
/* Drop old route. */
skb_dst_drop(skb);
skb_dst_set(skb, &rt->dst);
if (skb_dst(skb)->error)
- return -1;
+ return skb_dst(skb)->error;
#ifdef CONFIG_XFRM
if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
@@ -56,7 +56,7 @@ int ip_route_me_harder(struct sk_buff *skb, unsigned int addr_type)
skb_dst_set(skb, NULL);
dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
if (IS_ERR(dst))
- return -1;
+ return PTR_ERR(dst);;
skb_dst_set(skb, dst);
}
#endif
@@ -66,7 +66,7 @@ int ip_route_me_harder(struct sk_buff *skb, unsigned int addr_type)
if (skb_headroom(skb) < hh_len &&
pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
0, GFP_ATOMIC))
- return -1;
+ return -ENOMEM;
return 0;
}
diff --git a/net/ipv4/netfilter/iptable_mangle.c b/net/ipv4/netfilter/iptable_mangle.c
index 85d88f2..cba5658 100644
--- a/net/ipv4/netfilter/iptable_mangle.c
+++ b/net/ipv4/netfilter/iptable_mangle.c
@@ -44,6 +44,7 @@ ipt_mangle_out(struct sk_buff *skb, const struct net_device *out)
u_int8_t tos;
__be32 saddr, daddr;
u_int32_t mark;
+ int err;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct iphdr) ||
@@ -66,9 +67,11 @@ ipt_mangle_out(struct sk_buff *skb, const struct net_device *out)
if (iph->saddr != saddr ||
iph->daddr != daddr ||
skb->mark != mark ||
- iph->tos != tos)
- if (ip_route_me_harder(skb, RTN_UNSPEC))
- ret = NF_DROP;
+ iph->tos != tos) {
+ err = ip_route_me_harder(skb, RTN_UNSPEC);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
+ }
}
return ret;
diff --git a/net/ipv4/netfilter/iptable_nat.c b/net/ipv4/netfilter/iptable_nat.c
index eeaff7e..c2937c8 100644
--- a/net/ipv4/netfilter/iptable_nat.c
+++ b/net/ipv4/netfilter/iptable_nat.c
@@ -213,6 +213,7 @@ nf_nat_ipv4_local_fn(unsigned int hooknum,
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
unsigned int ret;
+ int err;
/* root is playing with raw sockets. */
if (skb->len < sizeof(struct iphdr) ||
@@ -226,8 +227,9 @@ nf_nat_ipv4_local_fn(unsigned int hooknum,
if (ct->tuplehash[dir].tuple.dst.u3.ip !=
ct->tuplehash[!dir].tuple.src.u3.ip) {
- if (ip_route_me_harder(skb, RTN_UNSPEC))
- ret = NF_DROP;
+ err = ip_route_me_harder(skb, RTN_UNSPEC);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
}
#ifdef CONFIG_XFRM
else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
--
1.8.1.4
--
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