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    Subject[PATCH 4.19 092/101] vrf: Fix fast path output packet handling with async Netfilter rules
    Date
    From: Martin Willi <martin@strongswan.org>

    [ Upstream commit 9e2b7fa2df4365e99934901da4fb4af52d81e820 ]

    VRF devices use an optimized direct path on output if a default qdisc
    is involved, calling Netfilter hooks directly. This path, however, does
    not consider Netfilter rules completing asynchronously, such as with
    NFQUEUE. The Netfilter okfn() is called for asynchronously accepted
    packets, but the VRF never passes that packet down the stack to send
    it out over the slave device. Using the slower redirect path for this
    seems not feasible, as we do not know beforehand if a Netfilter hook
    has asynchronously completing rules.

    Fix the use of asynchronously completing Netfilter rules in OUTPUT and
    POSTROUTING by using a special completion function that additionally
    calls dst_output() to pass the packet down the stack. Also, slightly
    adjust the use of nf_reset_ct() so that is called in the asynchronous
    case, too.

    Fixes: dcdd43c41e60 ("net: vrf: performance improvements for IPv4")
    Fixes: a9ec54d1b0cd ("net: vrf: performance improvements for IPv6")
    Signed-off-by: Martin Willi <martin@strongswan.org>
    Link: https://lore.kernel.org/r/20201106073030.3974927-1-martin@strongswan.org
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/net/vrf.c | 92 ++++++++++++++++++++++++++++++++++++++++--------------
    1 file changed, 69 insertions(+), 23 deletions(-)

    --- a/drivers/net/vrf.c
    +++ b/drivers/net/vrf.c
    @@ -336,8 +336,7 @@ static netdev_tx_t vrf_xmit(struct sk_bu
    return ret;
    }

    -static int vrf_finish_direct(struct net *net, struct sock *sk,
    - struct sk_buff *skb)
    +static void vrf_finish_direct(struct sk_buff *skb)
    {
    struct net_device *vrf_dev = skb->dev;

    @@ -356,7 +355,8 @@ static int vrf_finish_direct(struct net
    skb_pull(skb, ETH_HLEN);
    }

    - return 1;
    + /* reset skb device */
    + nf_reset(skb);
    }

    #if IS_ENABLED(CONFIG_IPV6)
    @@ -435,15 +435,41 @@ static struct sk_buff *vrf_ip6_out_redir
    return skb;
    }

    +static int vrf_output6_direct_finish(struct net *net, struct sock *sk,
    + struct sk_buff *skb)
    +{
    + vrf_finish_direct(skb);
    +
    + return vrf_ip6_local_out(net, sk, skb);
    +}
    +
    static int vrf_output6_direct(struct net *net, struct sock *sk,
    struct sk_buff *skb)
    {
    + int err = 1;
    +
    skb->protocol = htons(ETH_P_IPV6);

    - return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
    - net, sk, skb, NULL, skb->dev,
    - vrf_finish_direct,
    - !(IPCB(skb)->flags & IPSKB_REROUTED));
    + if (!(IPCB(skb)->flags & IPSKB_REROUTED))
    + err = nf_hook(NFPROTO_IPV6, NF_INET_POST_ROUTING, net, sk, skb,
    + NULL, skb->dev, vrf_output6_direct_finish);
    +
    + if (likely(err == 1))
    + vrf_finish_direct(skb);
    +
    + return err;
    +}
    +
    +static int vrf_ip6_out_direct_finish(struct net *net, struct sock *sk,
    + struct sk_buff *skb)
    +{
    + int err;
    +
    + err = vrf_output6_direct(net, sk, skb);
    + if (likely(err == 1))
    + err = vrf_ip6_local_out(net, sk, skb);
    +
    + return err;
    }

    static struct sk_buff *vrf_ip6_out_direct(struct net_device *vrf_dev,
    @@ -456,18 +482,15 @@ static struct sk_buff *vrf_ip6_out_direc
    skb->dev = vrf_dev;

    err = nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, net, sk,
    - skb, NULL, vrf_dev, vrf_output6_direct);
    + skb, NULL, vrf_dev, vrf_ip6_out_direct_finish);

    if (likely(err == 1))
    err = vrf_output6_direct(net, sk, skb);

    - /* reset skb device */
    if (likely(err == 1))
    - nf_reset(skb);
    - else
    - skb = NULL;
    + return skb;

    - return skb;
    + return NULL;
    }

    static struct sk_buff *vrf_ip6_out(struct net_device *vrf_dev,
    @@ -649,15 +672,41 @@ static struct sk_buff *vrf_ip_out_redire
    return skb;
    }

    +static int vrf_output_direct_finish(struct net *net, struct sock *sk,
    + struct sk_buff *skb)
    +{
    + vrf_finish_direct(skb);
    +
    + return vrf_ip_local_out(net, sk, skb);
    +}
    +
    static int vrf_output_direct(struct net *net, struct sock *sk,
    struct sk_buff *skb)
    {
    + int err = 1;
    +
    skb->protocol = htons(ETH_P_IP);

    - return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
    - net, sk, skb, NULL, skb->dev,
    - vrf_finish_direct,
    - !(IPCB(skb)->flags & IPSKB_REROUTED));
    + if (!(IPCB(skb)->flags & IPSKB_REROUTED))
    + err = nf_hook(NFPROTO_IPV4, NF_INET_POST_ROUTING, net, sk, skb,
    + NULL, skb->dev, vrf_output_direct_finish);
    +
    + if (likely(err == 1))
    + vrf_finish_direct(skb);
    +
    + return err;
    +}
    +
    +static int vrf_ip_out_direct_finish(struct net *net, struct sock *sk,
    + struct sk_buff *skb)
    +{
    + int err;
    +
    + err = vrf_output_direct(net, sk, skb);
    + if (likely(err == 1))
    + err = vrf_ip_local_out(net, sk, skb);
    +
    + return err;
    }

    static struct sk_buff *vrf_ip_out_direct(struct net_device *vrf_dev,
    @@ -670,18 +719,15 @@ static struct sk_buff *vrf_ip_out_direct
    skb->dev = vrf_dev;

    err = nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, net, sk,
    - skb, NULL, vrf_dev, vrf_output_direct);
    + skb, NULL, vrf_dev, vrf_ip_out_direct_finish);

    if (likely(err == 1))
    err = vrf_output_direct(net, sk, skb);

    - /* reset skb device */
    if (likely(err == 1))
    - nf_reset(skb);
    - else
    - skb = NULL;
    + return skb;

    - return skb;
    + return NULL;
    }

    static struct sk_buff *vrf_ip_out(struct net_device *vrf_dev,

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