[PATCH net] ipv4: Initialize flowi4_multipath_hash in data path

[PATCH net] ipv4: Initialize flowi4_multipath_hash in data path

[David Ahern]

From: David Ahern <dsahern@gmail.com>

flowi4_multipath_hash was added by the commit referenced below for
tunnels. Unfortunately, the patch did not initialize the new field
for several fast path lookups that do not initialize the entire flow
struct to 0. Fix those locations. Currently, flowi4_multipath_hash
is random garbage and affects the hash value computed by
fib_multipath_hash for multipath selection.

Fixes: 24ba14406c5c ("route: Add multipath_hash in flowi_common to make user-define hash")
Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: wenxu <wenxu@ucloud.cn>
---
 include/net/flow.h      | 1 +
 net/core/filter.c       | 1 +
 net/ipv4/fib_frontend.c | 1 +
 net/ipv4/route.c        | 1 +
 4 files changed, 4 insertions(+)

diff --git a/include/net/flow.h b/include/net/flow.h
index 929d3ca614d0..b2531df3f65f 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -116,6 +116,7 @@ static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
 	fl4->saddr = saddr;
 	fl4->fl4_dport = dport;
 	fl4->fl4_sport = sport;
+	fl4->flowi4_multipath_hash = 0;
 }
 
 /* Reset some input parameters after previous lookup */
diff --git a/net/core/filter.c b/net/core/filter.c
index 1f647ab986b6..1b168371ba96 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4838,6 +4838,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
 	fl4.saddr = params->ipv4_src;
 	fl4.fl4_sport = params->sport;
 	fl4.fl4_dport = params->dport;
+	fl4.flowi4_multipath_hash = 0;
 
 	if (flags & BPF_FIB_LOOKUP_DIRECT) {
 		u32 tbid = l3mdev_fib_table_rcu(dev) ? : RT_TABLE_MAIN;
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 41079490a118..86a23e4a6a50 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -362,6 +362,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 	fl4.flowi4_tun_key.tun_id = 0;
 	fl4.flowi4_flags = 0;
 	fl4.flowi4_uid = sock_net_uid(net, NULL);
+	fl4.flowi4_multipath_hash = 0;
 
 	no_addr = idev->ifa_list == NULL;
 
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 8ca6bcab7b03..e5f210d00851 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2147,6 +2147,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	fl4.daddr = daddr;
 	fl4.saddr = saddr;
 	fl4.flowi4_uid = sock_net_uid(net, NULL);
+	fl4.flowi4_multipath_hash = 0;
 
 	if (fib4_rules_early_flow_dissect(net, skb, &fl4, &_flkeys)) {
 		flkeys = &_flkeys;
-- 
2.24.3 (Apple Git-128)

Re: [PATCH net] ipv4: Initialize flowi4_multipath_hash in data path

[David Miller]

From: David Ahern <dsahern@kernel.org>
Date: Sun, 13 Sep 2020 12:43:39 -0600

> From: David Ahern <dsahern@gmail.com>
> 
> flowi4_multipath_hash was added by the commit referenced below for
> tunnels. Unfortunately, the patch did not initialize the new field
> for several fast path lookups that do not initialize the entire flow
> struct to 0. Fix those locations. Currently, flowi4_multipath_hash
> is random garbage and affects the hash value computed by
> fib_multipath_hash for multipath selection.
> 
> Fixes: 24ba14406c5c ("route: Add multipath_hash in flowi_common to make user-define hash")
> Signed-off-by: David Ahern <dsahern@gmail.com>
> Cc: wenxu <wenxu@ucloud.cn>

Applied and queued up for -stable, thanks David.