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Date: Wed, 8 Apr 2015 15:03:29 +0100
From: Robert Shearman <rshearma@...cade.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
CC: "davem@...emloft.net" <davem@...emloft.net>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v3 4/4] mpls: Allow payload type to be associated
with label routes
On 07/04/15 18:19, Eric W. Biederman wrote:
> Robert Shearman <rshearma@...cade.com> writes:
>
>> RFC 4182 s2 states that if an IPv4 Explicit NULL label is the only
>> label on the stack, then after popping the resulting packet must be
>> treated as a IPv4 packet and forwarded based on the IPv4 header. The
>> same is true for IPv6 Explicit NULL with an IPv6 packet following.
>>
>> Therefore, when installing the IPv4/IPv6 Explicit NULL label routes,
>> add an attribute that specifies the expected payload type for use at
>> forwarding time for determining the type of the encapsulated packet
>> instead of inspecting the first nibble of the packet.
>
> This looks pretty reasonable.
>
> I suspect the multiple returns instead of using a single variable
> might generate slightly worse machine but whatever.
That's a good point - the way the changes are structured now means that
the removal of the local variable doesn't add anything, so if it's OK
with you I'll change that.
>
> Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
Thanks for the review Eric.
Rob
>
>
>> Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
>> Signed-off-by: Robert Shearman <rshearma@...cade.com>
>> ---
>> net/mpls/af_mpls.c | 72 ++++++++++++++++++++++++++++++++----------------------
>> 1 file changed, 43 insertions(+), 29 deletions(-)
>>
>> diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
>> index 0b0420bf110d..e9ce5799449d 100644
>> --- a/net/mpls/af_mpls.c
>> +++ b/net/mpls/af_mpls.c
>> @@ -23,13 +23,25 @@
>> /* This maximum ha length copied from the definition of struct neighbour */
>> #define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, sizeof(unsigned long)))
>>
>> +enum mpls_payload_type {
>> + MPT_UNSPEC, /* IPv4 or IPv6 */
>> + MPT_IPV4 = 4,
>> + MPT_IPV6 = 6,
>> +
>> + /* Other types not implemented:
>> + * - Pseudo-wire with or without control word (RFC4385)
>> + * - GAL (RFC5586)
>> + */
>> +};
>> +
>> struct mpls_route { /* next hop label forwarding entry */
>> struct net_device __rcu *rt_dev;
>> struct rcu_head rt_rcu;
>> u32 rt_label[MAX_NEW_LABELS];
>> u8 rt_protocol; /* routing protocol that set this entry */
>> u8 rt_unlabeled : 1;
>> - u8 rt_labels : 7;
>> + u8 rt_payload_type : 3;
>> + u8 rt_labels : 4;
>> u8 rt_via_alen;
>> u8 rt_via_table;
>> u8 rt_via[0];
>> @@ -90,16 +102,7 @@ static bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
>> static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
>> struct mpls_entry_decoded dec)
>> {
>> - /* RFC4385 and RFC5586 encode other packets in mpls such that
>> - * they don't conflict with the ip version number, making
>> - * decoding by examining the ip version correct in everything
>> - * except for the strangest cases.
>> - *
>> - * The strange cases if we choose to support them will require
>> - * manual configuration.
>> - */
>> - struct iphdr *hdr4;
>> - bool success = true;
>> + enum mpls_payload_type payload_type;
>>
>> /* The IPv4 code below accesses through the IPv4 header
>> * checksum, which is 12 bytes into the packet.
>> @@ -114,24 +117,31 @@ static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
>> if (!pskb_may_pull(skb, 12))
>> return false;
>>
>> - /* Use ip_hdr to find the ip protocol version */
>> - hdr4 = ip_hdr(skb);
>> - if (hdr4->version == 4) {
>> + payload_type = rt->rt_payload_type;
>> + if (payload_type == MPT_UNSPEC)
>> + payload_type = ip_hdr(skb)->version;
>> +
>> + switch (payload_type) {
>> + case MPT_IPV4: {
>> + struct iphdr *hdr4 = ip_hdr(skb);
>> skb->protocol = htons(ETH_P_IP);
>> csum_replace2(&hdr4->check,
>> htons(hdr4->ttl << 8),
>> htons(dec.ttl << 8));
>> hdr4->ttl = dec.ttl;
>> + return true;
>> }
>> - else if (hdr4->version == 6) {
>> + case MPT_IPV6: {
>> struct ipv6hdr *hdr6 = ipv6_hdr(skb);
>> skb->protocol = htons(ETH_P_IPV6);
>> hdr6->hop_limit = dec.ttl;
>> + return true;
>> + }
>> + case MPT_UNSPEC:
>> + break;
>> }
>> - else
>> - /* version 0 and version 1 are used by pseudo wires */
>> - success = false;
>> - return success;
>> +
>> + return false;
>> }
>>
>> static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
>> @@ -254,16 +264,17 @@ static const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {
>> };
>>
>> struct mpls_route_config {
>> - u32 rc_protocol;
>> - u32 rc_ifindex;
>> - u16 rc_via_table;
>> - u16 rc_via_alen;
>> - u8 rc_via[MAX_VIA_ALEN];
>> - u32 rc_label;
>> - u32 rc_output_labels;
>> - u32 rc_output_label[MAX_NEW_LABELS];
>> - u32 rc_nlflags;
>> - struct nl_info rc_nlinfo;
>> + u32 rc_protocol;
>> + u32 rc_ifindex;
>> + u16 rc_via_table;
>> + u16 rc_via_alen;
>> + u8 rc_via[MAX_VIA_ALEN];
>> + u32 rc_label;
>> + u32 rc_output_labels;
>> + u32 rc_output_label[MAX_NEW_LABELS];
>> + u32 rc_nlflags;
>> + enum mpls_payload_type rc_payload_type;
>> + struct nl_info rc_nlinfo;
>> };
>>
>> static struct mpls_route *mpls_rt_alloc(size_t alen)
>> @@ -414,6 +425,7 @@ static int mpls_route_add(struct mpls_route_config *cfg)
>> }
>> rt->rt_protocol = cfg->rc_protocol;
>> RCU_INIT_POINTER(rt->rt_dev, dev);
>> + rt->rt_payload_type = cfg->rc_payload_type;
>> rt->rt_via_table = cfg->rc_via_table;
>> memcpy(rt->rt_via, cfg->rc_via, cfg->rc_via_alen);
>>
>> @@ -949,6 +961,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
>> goto nort0;
>> RCU_INIT_POINTER(rt0->rt_dev, lo);
>> rt0->rt_protocol = RTPROT_KERNEL;
>> + rt0->rt_payload_type = MPT_IPV4;
>> rt0->rt_via_table = NEIGH_LINK_TABLE;
>> memcpy(rt0->rt_via, lo->dev_addr, lo->addr_len);
>> }
>> @@ -959,6 +972,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
>> goto nort2;
>> RCU_INIT_POINTER(rt2->rt_dev, lo);
>> rt2->rt_protocol = RTPROT_KERNEL;
>> + rt2->rt_payload_type = MPT_IPV6;
>> rt2->rt_via_table = NEIGH_LINK_TABLE;
>> memcpy(rt2->rt_via, lo->dev_addr, lo->addr_len);
>> }
--
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