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Message-ID: <20150131171121.GB31871@redhat.com>
Date: Sat, 31 Jan 2015 19:11:21 +0200
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Vladislav Yasevich <vyasevich@...il.com>
Cc: netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org,
ben@...adent.org.uk, eric.dumazet@...il.com,
hannes@...essinduktion.org,
Vladislav Yasevich <vyasevic@...hat.com>
Subject: Re: [PATCH v2 1/3] ipv6: Select fragment id during UFO segmentation
if not set.
On Fri, Jan 30, 2015 at 02:27:25PM -0500, Vladislav Yasevich wrote:
> If the IPv6 fragment id has not been set and we perform
> fragmentation due to UFO, select a new fragment id.
> We now consider a fragment id of 0 as unset and if id selection
> process returns 0 (after all the pertrubations), we set it to
> 0x80000000, thus giving us ample space not to create collisions
> with the next packet we may have to fragment.
>
> When doing UFO integrity checking, we also select the
> fragment id if it has not be set yet. This is stored into
s/be/been/
> the skb_shinfo() thus allowing UFO to function correclty.
>
> This patch also removes duplicate fragment id generation code
> and moves ipv6_select_ident() into the header as it may be
> used during GSO.
>
> Signed-off-by: Vladislav Yasevich <vyasevic@...hat.com>
Acked-by: Michael S. Tsirkin <mst@...hat.com>
> ---
> include/net/ipv6.h | 3 +++
> net/ipv6/ip6_output.c | 10 ++++------
> net/ipv6/output_core.c | 28 ++++++++++++++++++++++------
> net/ipv6/udp_offload.c | 10 +++++++++-
> 4 files changed, 38 insertions(+), 13 deletions(-)
>
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> index 4292929..9bf85d3 100644
> --- a/include/net/ipv6.h
> +++ b/include/net/ipv6.h
> @@ -671,6 +671,9 @@ static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_add
> return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));
> }
>
> +u32 __ipv6_select_ident(u32 hashrnd, struct in6_addr *dst,
> + struct in6_addr *src);
> +void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt);
> void ipv6_proxy_select_ident(struct sk_buff *skb);
>
> int ip6_dst_hoplimit(struct dst_entry *dst);
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index ce69a12..5dc91fe 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -537,17 +537,15 @@ static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
> skb_copy_secmark(to, from);
> }
>
> -static void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
> +void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
> {
> static u32 ip6_idents_hashrnd __read_mostly;
> - u32 hash, id;
> + u32 id;
>
> net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
>
> - hash = __ipv6_addr_jhash(&rt->rt6i_dst.addr, ip6_idents_hashrnd);
> - hash = __ipv6_addr_jhash(&rt->rt6i_src.addr, hash);
> -
> - id = ip_idents_reserve(hash, 1);
> + id = __ipv6_select_ident(ip6_idents_hashrnd, &rt->rt6i_dst.addr,
> + &rt->rt6i_src.addr);
> fhdr->identification = htonl(id);
> }
>
> diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
> index 97f41a3..ceb857d 100644
> --- a/net/ipv6/output_core.c
> +++ b/net/ipv6/output_core.c
> @@ -9,6 +9,24 @@
> #include <net/addrconf.h>
> #include <net/secure_seq.h>
>
> +u32 __ipv6_select_ident(u32 hashrnd, struct in6_addr *dst, struct in6_addr *src)
> +{
> + u32 hash, id;
> +
> + hash = __ipv6_addr_jhash(dst, hashrnd);
> + hash = __ipv6_addr_jhash(src, hash);
> +
> + /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
> + * set the hight order instead thus minimizing possible future
> + * collisions.
> + */
> + id = ip_idents_reserve(hash, 1);
> + if (unlikely(!id))
> + id = 1 << 31;
> +
> + return id;
> +}
> +
> /* This function exists only for tap drivers that must support broken
> * clients requesting UFO without specifying an IPv6 fragment ID.
> *
> @@ -22,7 +40,7 @@ void ipv6_proxy_select_ident(struct sk_buff *skb)
> static u32 ip6_proxy_idents_hashrnd __read_mostly;
> struct in6_addr buf[2];
> struct in6_addr *addrs;
> - u32 hash, id;
> + u32 id;
>
> addrs = skb_header_pointer(skb,
> skb_network_offset(skb) +
> @@ -34,11 +52,9 @@ void ipv6_proxy_select_ident(struct sk_buff *skb)
> net_get_random_once(&ip6_proxy_idents_hashrnd,
> sizeof(ip6_proxy_idents_hashrnd));
>
> - hash = __ipv6_addr_jhash(&addrs[1], ip6_proxy_idents_hashrnd);
> - hash = __ipv6_addr_jhash(&addrs[0], hash);
> -
> - id = ip_idents_reserve(hash, 1);
> - skb_shinfo(skb)->ip6_frag_id = htonl(id);
> + id = __ipv6_select_ident(ip6_proxy_idents_hashrnd,
> + &addrs[1], &addrs[0]);
> + skb_shinfo(skb)->ip6_frag_id = id;
> }
> EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
>
> diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
> index b6aa8ed..a562769 100644
> --- a/net/ipv6/udp_offload.c
> +++ b/net/ipv6/udp_offload.c
> @@ -52,6 +52,10 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
>
> skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
>
> + /* Set the IPv6 fragment id if not set yet */
> + if (!skb_shinfo(skb)->ip6_frag_id)
> + ipv6_proxy_select_ident(skb);
> +
> segs = NULL;
> goto out;
> }
> @@ -108,7 +112,11 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
> fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
> fptr->nexthdr = nexthdr;
> fptr->reserved = 0;
> - fptr->identification = skb_shinfo(skb)->ip6_frag_id;
> + if (skb_shinfo(skb)->ip6_frag_id)
> + fptr->identification = skb_shinfo(skb)->ip6_frag_id;
> + else
> + ipv6_select_ident(fptr,
> + (struct rt6_info *)skb_dst(skb));
>
> /* Fragment the skb. ipv6 header and the remaining fields of the
> * fragment header are updated in ipv6_gso_segment()
> --
> 1.9.3
--
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