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Message-ID: <9AAE0902D5BC7E449B7C8E4E778ABCD0204A79@AMSPEX01CL01.citrite.net>
Date: Mon, 13 Jan 2014 11:26:39 +0000
From: Paul Durrant <Paul.Durrant@...rix.com>
To: Paul Durrant <Paul.Durrant@...rix.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"xen-devel@...ts.xen.org" <xen-devel@...ts.xen.org>
CC: David Miller <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Veaceslav Falico <vfalico@...hat.com>,
Alexander Duyck <alexander.h.duyck@...el.com>,
Nicolas Dichtel <nicolas.dichtel@...nd.com>
Subject: RE: [PATCH net-next v2 1/3] net: add skb_checksum_setup
> -----Original Message-----
> From: Paul Durrant [mailto:paul.durrant@...rix.com]
> Sent: 09 January 2014 10:03
> To: netdev@...r.kernel.org; xen-devel@...ts.xen.org
> Cc: Paul Durrant; David Miller; Eric Dumazet; Veaceslav Falico; Alexander
> Duyck; Nicolas Dichtel
> Subject: [PATCH net-next v2 1/3] net: add skb_checksum_setup
>
> This patch adds a function to set up the partial checksum offset for IP
> packets (and optionally re-calculate the pseudo-header checksum) into the
> core network code.
> The implementation was previously private and duplicated between xen-
> netback
> and xen-netfront, however it is not xen-specific and is potentially useful
> to any network driver.
>
> Signed-off-by: Paul Durrant <paul.durrant@...rix.com>
> Cc: David Miller <davem@...emloft.net>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Veaceslav Falico <vfalico@...hat.com>
> Cc: Alexander Duyck <alexander.h.duyck@...el.com>
> Cc: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Ping?
Paul
> ---
> include/linux/skbuff.h | 2 +
> net/core/skbuff.c | 273
> ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 275 insertions(+)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index d97f2d0..48b7605 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2893,6 +2893,8 @@ static inline void skb_checksum_none_assert(const
> struct sk_buff *skb)
>
> bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
>
> +int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
> +
> u32 __skb_get_poff(const struct sk_buff *skb);
>
> /**
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 1d641e7..15057d2 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -65,6 +65,7 @@
> #include <net/dst.h>
> #include <net/sock.h>
> #include <net/checksum.h>
> +#include <net/ip6_checksum.h>
> #include <net/xfrm.h>
>
> #include <asm/uaccess.h>
> @@ -3549,6 +3550,278 @@ bool skb_partial_csum_set(struct sk_buff *skb,
> u16 start, u16 off)
> }
> EXPORT_SYMBOL_GPL(skb_partial_csum_set);
>
> +static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
> + unsigned int max)
> +{
> + if (skb_headlen(skb) >= len)
> + return 0;
> +
> + /* If we need to pullup then pullup to the max, so we
> + * won't need to do it again.
> + */
> + if (max > skb->len)
> + max = skb->len;
> +
> + if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
> + return -ENOMEM;
> +
> + if (skb_headlen(skb) < len)
> + return -EPROTO;
> +
> + return 0;
> +}
> +
> +/* This value should be large enough to cover a tagged ethernet header
> plus
> + * maximally sized IP and TCP or UDP headers.
> + */
> +#define MAX_IP_HDR_LEN 128
> +
> +static int skb_checksum_setup_ip(struct sk_buff *skb, bool recalculate)
> +{
> + unsigned int off;
> + bool fragment;
> + int err;
> +
> + fragment = false;
> +
> + err = skb_maybe_pull_tail(skb,
> + sizeof(struct iphdr),
> + MAX_IP_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
> + fragment = true;
> +
> + off = ip_hdrlen(skb);
> +
> + err = -EPROTO;
> +
> + if (fragment)
> + goto out;
> +
> + switch (ip_hdr(skb)->protocol) {
> + case IPPROTO_TCP:
> + err = skb_maybe_pull_tail(skb,
> + off + sizeof(struct tcphdr),
> + MAX_IP_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + if (!skb_partial_csum_set(skb, off,
> + offsetof(struct tcphdr, check))) {
> + err = -EPROTO;
> + goto out;
> + }
> +
> + if (recalculate)
> + tcp_hdr(skb)->check =
> + ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
> + ip_hdr(skb)->daddr,
> + skb->len - off,
> + IPPROTO_TCP, 0);
> + break;
> + case IPPROTO_UDP:
> + err = skb_maybe_pull_tail(skb,
> + off + sizeof(struct udphdr),
> + MAX_IP_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + if (!skb_partial_csum_set(skb, off,
> + offsetof(struct udphdr, check))) {
> + err = -EPROTO;
> + goto out;
> + }
> +
> + if (recalculate)
> + udp_hdr(skb)->check =
> + ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
> + ip_hdr(skb)->daddr,
> + skb->len - off,
> + IPPROTO_UDP, 0);
> + break;
> + default:
> + goto out;
> + }
> +
> + err = 0;
> +
> +out:
> + return err;
> +}
> +
> +/* This value should be large enough to cover a tagged ethernet header
> plus
> + * an IPv6 header, all options, and a maximal TCP or UDP header.
> + */
> +#define MAX_IPV6_HDR_LEN 256
> +
> +#define OPT_HDR(type, skb, off) \
> + (type *)(skb_network_header(skb) + (off))
> +
> +static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
> +{
> + int err;
> + u8 nexthdr;
> + unsigned int off;
> + unsigned int len;
> + bool fragment;
> + bool done;
> +
> + fragment = false;
> + done = false;
> +
> + off = sizeof(struct ipv6hdr);
> +
> + err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + nexthdr = ipv6_hdr(skb)->nexthdr;
> +
> + len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
> + while (off <= len && !done) {
> + switch (nexthdr) {
> + case IPPROTO_DSTOPTS:
> + case IPPROTO_HOPOPTS:
> + case IPPROTO_ROUTING: {
> + struct ipv6_opt_hdr *hp;
> +
> + err = skb_maybe_pull_tail(skb,
> + off +
> + sizeof(struct ipv6_opt_hdr),
> + MAX_IPV6_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
> + nexthdr = hp->nexthdr;
> + off += ipv6_optlen(hp);
> + break;
> + }
> + case IPPROTO_AH: {
> + struct ip_auth_hdr *hp;
> +
> + err = skb_maybe_pull_tail(skb,
> + off +
> + sizeof(struct ip_auth_hdr),
> + MAX_IPV6_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + hp = OPT_HDR(struct ip_auth_hdr, skb, off);
> + nexthdr = hp->nexthdr;
> + off += ipv6_authlen(hp);
> + break;
> + }
> + case IPPROTO_FRAGMENT: {
> + struct frag_hdr *hp;
> +
> + err = skb_maybe_pull_tail(skb,
> + off +
> + sizeof(struct frag_hdr),
> + MAX_IPV6_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + hp = OPT_HDR(struct frag_hdr, skb, off);
> +
> + if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
> + fragment = true;
> +
> + nexthdr = hp->nexthdr;
> + off += sizeof(struct frag_hdr);
> + break;
> + }
> + default:
> + done = true;
> + break;
> + }
> + }
> +
> + err = -EPROTO;
> +
> + if (!done || fragment)
> + goto out;
> +
> + switch (nexthdr) {
> + case IPPROTO_TCP:
> + err = skb_maybe_pull_tail(skb,
> + off + sizeof(struct tcphdr),
> + MAX_IPV6_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + if (!skb_partial_csum_set(skb, off,
> + offsetof(struct tcphdr, check))) {
> + err = -EPROTO;
> + goto out;
> + }
> +
> + if (recalculate)
> + tcp_hdr(skb)->check =
> + ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
> + &ipv6_hdr(skb)->daddr,
> + skb->len - off,
> + IPPROTO_TCP, 0);
> + break;
> + case IPPROTO_UDP:
> + err = skb_maybe_pull_tail(skb,
> + off + sizeof(struct udphdr),
> + MAX_IPV6_HDR_LEN);
> + if (err < 0)
> + goto out;
> +
> + if (!skb_partial_csum_set(skb, off,
> + offsetof(struct udphdr, check))) {
> + err = -EPROTO;
> + goto out;
> + }
> +
> + if (recalculate)
> + udp_hdr(skb)->check =
> + ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
> + &ipv6_hdr(skb)->daddr,
> + skb->len - off,
> + IPPROTO_UDP, 0);
> + break;
> + default:
> + goto out;
> + }
> +
> + err = 0;
> +
> +out:
> + return err;
> +}
> +
> +/**
> + * skb_checksum_setup - set up partial checksum offset
> + * @skb: the skb to set up
> + * @recalculate: if true the pseudo-header checksum will be recalculated
> + */
> +int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
> +{
> + int err;
> +
> + switch (skb->protocol) {
> + case htons(ETH_P_IP):
> + err = skb_checksum_setup_ip(skb, recalculate);
> + break;
> +
> + case htons(ETH_P_IPV6):
> + err = skb_checksum_setup_ipv6(skb, recalculate);
> + break;
> +
> + default:
> + err = -EPROTO;
> + break;
> + }
> +
> + return err;
> +}
> +EXPORT_SYMBOL(skb_checksum_setup);
> +
> void __skb_warn_lro_forwarding(const struct sk_buff *skb)
> {
> net_warn_ratelimited("%s: received packets cannot be forwarded
> while LRO is enabled\n",
> --
> 1.7.10.4
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