summaryrefslogtreecommitdiff
path: root/net/ipv4
diff options
context:
space:
mode:
authorGuillaume Nault <gnault@redhat.com>2022-03-17 13:45:09 +0100
committerJakub Kicinski <kuba@kernel.org>2022-03-18 14:06:45 -0700
commit544b4dd568e3b09c1ab38a759d3187e7abda11a0 (patch)
tree2537d6ff122d9842f4f467db07ebb4451bb9fc1b /net/ipv4
parent6bd0c76bd70447aedfeafa9e1fcc249991d6c678 (diff)
ipv4: Fix route lookups when handling ICMP redirects and PMTU updates
The PMTU update and ICMP redirect helper functions initialise their fl4 variable with either __build_flow_key() or build_sk_flow_key(). These initialisation functions always set ->flowi4_scope with RT_SCOPE_UNIVERSE and might set the ECN bits of ->flowi4_tos. This is not a problem when the route lookup is later done via ip_route_output_key_hash(), which properly clears the ECN bits from ->flowi4_tos and initialises ->flowi4_scope based on the RTO_ONLINK flag. However, some helpers call fib_lookup() directly, without sanitising the tos and scope fields, so the route lookup can fail and, as a result, the ICMP redirect or PMTU update aren't taken into account. Fix this by extracting the ->flowi4_tos and ->flowi4_scope sanitisation code into ip_rt_fix_tos(), then use this function in handlers that call fib_lookup() directly. Note 1: We can't sanitise ->flowi4_tos and ->flowi4_scope in a central place (like __build_flow_key() or flowi4_init_output()), because ip_route_output_key_hash() expects non-sanitised values. When called with sanitised values, it can erroneously overwrite RT_SCOPE_LINK with RT_SCOPE_UNIVERSE in ->flowi4_scope. Therefore we have to be careful to sanitise the values only for those paths that don't call ip_route_output_key_hash(). Note 2: The problem is mostly about sanitising ->flowi4_tos. Having ->flowi4_scope initialised with RT_SCOPE_UNIVERSE instead of RT_SCOPE_LINK probably wasn't really a problem: sockets with the SOCK_LOCALROUTE flag set (those that'd result in RTO_ONLINK being set) normally shouldn't receive ICMP redirects or PMTU updates. Fixes: 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions.") Signed-off-by: Guillaume Nault <gnault@redhat.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/route.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f33ad1f383b6..d5d058de3664 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -499,6 +499,15 @@ void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
}
EXPORT_SYMBOL(__ip_select_ident);
+static void ip_rt_fix_tos(struct flowi4 *fl4)
+{
+ __u8 tos = RT_FL_TOS(fl4);
+
+ fl4->flowi4_tos = tos & IPTOS_RT_MASK;
+ fl4->flowi4_scope = tos & RTO_ONLINK ?
+ RT_SCOPE_LINK : RT_SCOPE_UNIVERSE;
+}
+
static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
const struct sock *sk,
const struct iphdr *iph,
@@ -824,6 +833,7 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf
rt = (struct rtable *) dst;
__build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
+ ip_rt_fix_tos(&fl4);
__ip_do_redirect(rt, skb, &fl4, true);
}
@@ -1048,6 +1058,7 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
struct flowi4 fl4;
ip_rt_build_flow_key(&fl4, sk, skb);
+ ip_rt_fix_tos(&fl4);
/* Don't make lookup fail for bridged encapsulations */
if (skb && netif_is_any_bridge_port(skb->dev))
@@ -1122,6 +1133,8 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
goto out;
new = true;
+ } else {
+ ip_rt_fix_tos(&fl4);
}
__ip_rt_update_pmtu((struct rtable *)xfrm_dst_path(&rt->dst), &fl4, mtu);
@@ -2603,7 +2616,6 @@ add:
struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
const struct sk_buff *skb)
{
- __u8 tos = RT_FL_TOS(fl4);
struct fib_result res = {
.type = RTN_UNSPEC,
.fi = NULL,
@@ -2613,9 +2625,7 @@ struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
struct rtable *rth;
fl4->flowi4_iif = LOOPBACK_IFINDEX;
- fl4->flowi4_tos = tos & IPTOS_RT_MASK;
- fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
- RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
+ ip_rt_fix_tos(fl4);
rcu_read_lock();
rth = ip_route_output_key_hash_rcu(net, fl4, &res, skb);