From c9e1673a0accf086dfce9b501d8bcb4ec6bbc1e9 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Fri, 5 Apr 2013 06:41:10 +0000 Subject: [PATCH] netfilter: ipv4: propagate routing errors from ip_route_me_harder() 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 Signed-off-by: Pablo Neira Ayuso --- 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 4c0cf63dd92e..8b201e8095cd 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 85d88f206447..cba5658ec82c 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 eeaff7e4acb5..c2937c81bb67 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) && -- 2.20.1