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net, bonding: Refactor bond_xmit_hash for use with xdp_buff
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In preparation for adding XDP support to the bonding driver
refactor the packet hashing functions to be able to work with
any linear data buffer without an skb.

Signed-off-by: Jussi Maki <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Cc: Jay Vosburgh <[email protected]>
Cc: Veaceslav Falico <[email protected]>
Cc: Andy Gospodarek <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]
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@joamaki @borkmann
joamaki authored and borkmann committed Aug 9, 2021
1 parent c83ae15 commit a815bde
Showing 1 changed file with 90 additions and 57 deletions.
147 changes: 90 additions & 57 deletions drivers/net/bonding/bond_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3614,55 +3614,80 @@ static struct notifier_block bond_netdev_notifier = {

/*---------------------------- Hashing Policies -----------------------------*/

/* Helper to access data in a packet, with or without a backing skb.
* If skb is given the data is linearized if necessary via pskb_may_pull.
*/
static inline const void *bond_pull_data(struct sk_buff *skb,
const void *data, int hlen, int n)
{
if (likely(n <= hlen))
return data;
else if (skb && likely(pskb_may_pull(skb, n)))
return skb->head;

return NULL;
}

/* L2 hash helper */
static inline u32 bond_eth_hash(struct sk_buff *skb)
static inline u32 bond_eth_hash(struct sk_buff *skb, const void *data, int mhoff, int hlen)
{
struct ethhdr *ep, hdr_tmp;
struct ethhdr *ep;

ep = skb_header_pointer(skb, 0, sizeof(hdr_tmp), &hdr_tmp);
if (ep)
return ep->h_dest[5] ^ ep->h_source[5] ^ ep->h_proto;
return 0;
data = bond_pull_data(skb, data, hlen, mhoff + sizeof(struct ethhdr));
if (!data)
return 0;

ep = (struct ethhdr *)(data + mhoff);
return ep->h_dest[5] ^ ep->h_source[5] ^ ep->h_proto;
}

static bool bond_flow_ip(struct sk_buff *skb, struct flow_keys *fk,
int *noff, int *proto, bool l34)
static bool bond_flow_ip(struct sk_buff *skb, struct flow_keys *fk, const void *data,
int hlen, __be16 l2_proto, int *nhoff, int *ip_proto, bool l34)
{
const struct ipv6hdr *iph6;
const struct iphdr *iph;

if (skb->protocol == htons(ETH_P_IP)) {
if (unlikely(!pskb_may_pull(skb, *noff + sizeof(*iph))))
if (l2_proto == htons(ETH_P_IP)) {
data = bond_pull_data(skb, data, hlen, *nhoff + sizeof(*iph));
if (!data)
return false;
iph = (const struct iphdr *)(skb->data + *noff);

iph = (const struct iphdr *)(data + *nhoff);
iph_to_flow_copy_v4addrs(fk, iph);
*noff += iph->ihl << 2;
*nhoff += iph->ihl << 2;
if (!ip_is_fragment(iph))
*proto = iph->protocol;
} else if (skb->protocol == htons(ETH_P_IPV6)) {
if (unlikely(!pskb_may_pull(skb, *noff + sizeof(*iph6))))
*ip_proto = iph->protocol;
} else if (l2_proto == htons(ETH_P_IPV6)) {
data = bond_pull_data(skb, data, hlen, *nhoff + sizeof(*iph6));
if (!data)
return false;
iph6 = (const struct ipv6hdr *)(skb->data + *noff);

iph6 = (const struct ipv6hdr *)(data + *nhoff);
iph_to_flow_copy_v6addrs(fk, iph6);
*noff += sizeof(*iph6);
*proto = iph6->nexthdr;
*nhoff += sizeof(*iph6);
*ip_proto = iph6->nexthdr;
} else {
return false;
}

if (l34 && *proto >= 0)
fk->ports.ports = skb_flow_get_ports(skb, *noff, *proto);
if (l34 && *ip_proto >= 0)
fk->ports.ports = __skb_flow_get_ports(skb, *nhoff, *ip_proto, data, hlen);

return true;
}

static u32 bond_vlan_srcmac_hash(struct sk_buff *skb)
static u32 bond_vlan_srcmac_hash(struct sk_buff *skb, const void *data, int mhoff, int hlen)
{
struct ethhdr *mac_hdr = (struct ethhdr *)skb_mac_header(skb);
struct ethhdr *mac_hdr;
u32 srcmac_vendor = 0, srcmac_dev = 0;
u16 vlan;
int i;

data = bond_pull_data(skb, data, hlen, mhoff + sizeof(struct ethhdr));
if (!data)
return 0;
mac_hdr = (struct ethhdr *)(data + mhoff);

for (i = 0; i < 3; i++)
srcmac_vendor = (srcmac_vendor << 8) | mac_hdr->h_source[i];

Expand All @@ -3678,49 +3703,46 @@ static u32 bond_vlan_srcmac_hash(struct sk_buff *skb)
}

/* Extract the appropriate headers based on bond's xmit policy */
static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb,
struct flow_keys *fk)
static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb, const void *data,
__be16 l2_proto, int nhoff, int hlen, struct flow_keys *fk)
{
bool l34 = bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER34;
int noff, proto = -1;
int ip_proto = -1;

switch (bond->params.xmit_policy) {
case BOND_XMIT_POLICY_ENCAP23:
case BOND_XMIT_POLICY_ENCAP34:
memset(fk, 0, sizeof(*fk));
return __skb_flow_dissect(NULL, skb, &flow_keys_bonding,
fk, NULL, 0, 0, 0, 0);
fk, data, l2_proto, nhoff, hlen, 0);
default:
break;
}

fk->ports.ports = 0;
memset(&fk->icmp, 0, sizeof(fk->icmp));
noff = skb_network_offset(skb);
if (!bond_flow_ip(skb, fk, &noff, &proto, l34))
if (!bond_flow_ip(skb, fk, data, hlen, l2_proto, &nhoff, &ip_proto, l34))
return false;

/* ICMP error packets contains at least 8 bytes of the header
* of the packet which generated the error. Use this information
* to correlate ICMP error packets within the same flow which
* generated the error.
*/
if (proto == IPPROTO_ICMP || proto == IPPROTO_ICMPV6) {
skb_flow_get_icmp_tci(skb, &fk->icmp, skb->data,
skb_transport_offset(skb),
skb_headlen(skb));
if (proto == IPPROTO_ICMP) {
if (ip_proto == IPPROTO_ICMP || ip_proto == IPPROTO_ICMPV6) {
skb_flow_get_icmp_tci(skb, &fk->icmp, data, nhoff, hlen);
if (ip_proto == IPPROTO_ICMP) {
if (!icmp_is_err(fk->icmp.type))
return true;

noff += sizeof(struct icmphdr);
} else if (proto == IPPROTO_ICMPV6) {
nhoff += sizeof(struct icmphdr);
} else if (ip_proto == IPPROTO_ICMPV6) {
if (!icmpv6_is_err(fk->icmp.type))
return true;

noff += sizeof(struct icmp6hdr);
nhoff += sizeof(struct icmp6hdr);
}
return bond_flow_ip(skb, fk, &noff, &proto, l34);
return bond_flow_ip(skb, fk, data, hlen, l2_proto, &nhoff, &ip_proto, l34);
}

return true;
Expand All @@ -3736,33 +3758,26 @@ static u32 bond_ip_hash(u32 hash, struct flow_keys *flow)
return hash >> 1;
}

/**
* bond_xmit_hash - generate a hash value based on the xmit policy
* @bond: bonding device
* @skb: buffer to use for headers
*
* This function will extract the necessary headers from the skb buffer and use
* them to generate a hash based on the xmit_policy set in the bonding device
/* Generate hash based on xmit policy. If @skb is given it is used to linearize
* the data as required, but this function can be used without it if the data is
* known to be linear (e.g. with xdp_buff).
*/
u32 bond_xmit_hash(struct bonding *bond, struct sk_buff *skb)
static u32 __bond_xmit_hash(struct bonding *bond, struct sk_buff *skb, const void *data,
__be16 l2_proto, int mhoff, int nhoff, int hlen)
{
struct flow_keys flow;
u32 hash;

if (bond->params.xmit_policy == BOND_XMIT_POLICY_ENCAP34 &&
skb->l4_hash)
return skb->hash;

if (bond->params.xmit_policy == BOND_XMIT_POLICY_VLAN_SRCMAC)
return bond_vlan_srcmac_hash(skb);
return bond_vlan_srcmac_hash(skb, data, mhoff, hlen);

if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER2 ||
!bond_flow_dissect(bond, skb, &flow))
return bond_eth_hash(skb);
!bond_flow_dissect(bond, skb, data, l2_proto, nhoff, hlen, &flow))
return bond_eth_hash(skb, data, mhoff, hlen);

if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER23 ||
bond->params.xmit_policy == BOND_XMIT_POLICY_ENCAP23) {
hash = bond_eth_hash(skb);
hash = bond_eth_hash(skb, data, mhoff, hlen);
} else {
if (flow.icmp.id)
memcpy(&hash, &flow.icmp, sizeof(hash));
Expand All @@ -3773,6 +3788,25 @@ u32 bond_xmit_hash(struct bonding *bond, struct sk_buff *skb)
return bond_ip_hash(hash, &flow);
}

/**
* bond_xmit_hash - generate a hash value based on the xmit policy
* @bond: bonding device
* @skb: buffer to use for headers
*
* This function will extract the necessary headers from the skb buffer and use
* them to generate a hash based on the xmit_policy set in the bonding device
*/
u32 bond_xmit_hash(struct bonding *bond, struct sk_buff *skb)
{
if (bond->params.xmit_policy == BOND_XMIT_POLICY_ENCAP34 &&
skb->l4_hash)
return skb->hash;

return __bond_xmit_hash(bond, skb, skb->head, skb->protocol,
skb->mac_header, skb->network_header,
skb_headlen(skb));
}

/*-------------------------- Device entry points ----------------------------*/

void bond_work_init_all(struct bonding *bond)
Expand Down Expand Up @@ -4434,8 +4468,7 @@ static netdev_tx_t bond_xmit_roundrobin(struct sk_buff *skb,
return bond_tx_drop(bond_dev, skb);
}

static struct slave *bond_xmit_activebackup_slave_get(struct bonding *bond,
struct sk_buff *skb)
static struct slave *bond_xmit_activebackup_slave_get(struct bonding *bond)
{
return rcu_dereference(bond->curr_active_slave);
}
Expand All @@ -4449,7 +4482,7 @@ static netdev_tx_t bond_xmit_activebackup(struct sk_buff *skb,
struct bonding *bond = netdev_priv(bond_dev);
struct slave *slave;

slave = bond_xmit_activebackup_slave_get(bond, skb);
slave = bond_xmit_activebackup_slave_get(bond);
if (slave)
return bond_dev_queue_xmit(bond, skb, slave->dev);

Expand Down Expand Up @@ -4747,7 +4780,7 @@ static struct net_device *bond_xmit_get_slave(struct net_device *master_dev,
slave = bond_xmit_roundrobin_slave_get(bond, skb);
break;
case BOND_MODE_ACTIVEBACKUP:
slave = bond_xmit_activebackup_slave_get(bond, skb);
slave = bond_xmit_activebackup_slave_get(bond);
break;
case BOND_MODE_8023AD:
case BOND_MODE_XOR:
Expand Down

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