136 lines
4.1 KiB
Diff
136 lines
4.1 KiB
Diff
From: Ben Hutchings <ben@decadent.org.uk>
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Date: Thu, 30 Oct 2014 18:27:17 +0000
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Subject: [2/2] drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO
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packets
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Origin: https://git.kernel.org/cgit/linux/kernel/git/davem/net.git/commit?id=5188cd44c55db3e92cd9e77a40b5baa7ed4340f7
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UFO is now disabled on all drivers that work with virtio net headers,
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but userland may try to send UFO/IPv6 packets anyway. Instead of
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sending with ID=0, we should select identifiers on their behalf (as we
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used to).
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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Fixes: 916e4cf46d02 ("ipv6: reuse ip6_frag_id from ip6_ufo_append_data")
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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drivers/net/macvtap.c | 3 +++
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drivers/net/tun.c | 6 +++++-
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include/net/ipv6.h | 2 ++
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net/ipv6/output_core.c | 34 ++++++++++++++++++++++++++++++++++
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4 files changed, 44 insertions(+), 1 deletion(-)
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--- a/drivers/net/macvtap.c
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+++ b/drivers/net/macvtap.c
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@@ -16,6 +16,7 @@
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#include <linux/idr.h>
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#include <linux/fs.h>
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+#include <net/ipv6.h>
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#include <net/net_namespace.h>
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#include <net/rtnetlink.h>
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#include <net/sock.h>
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@@ -572,6 +573,8 @@ static int macvtap_skb_from_vnet_hdr(str
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pr_warn_once("macvtap: %s: using disabled UFO feature; please fix this program\n",
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current->comm);
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gso_type = SKB_GSO_UDP;
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+ if (skb->protocol == htons(ETH_P_IPV6))
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+ ipv6_proxy_select_ident(skb);
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break;
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default:
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return -EINVAL;
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--- a/drivers/net/tun.c
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+++ b/drivers/net/tun.c
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@@ -65,6 +65,7 @@
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#include <linux/nsproxy.h>
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#include <linux/virtio_net.h>
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#include <linux/rcupdate.h>
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+#include <net/ipv6.h>
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#include <net/net_namespace.h>
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#include <net/netns/generic.h>
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#include <net/rtnetlink.h>
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@@ -1139,6 +1140,8 @@ static ssize_t tun_get_user(struct tun_s
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break;
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}
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+ skb_reset_network_header(skb);
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+
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if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
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pr_debug("GSO!\n");
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switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
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@@ -1159,6 +1162,8 @@ static ssize_t tun_get_user(struct tun_s
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current->comm);
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}
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skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
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+ if (skb->protocol == htons(ETH_P_IPV6))
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+ ipv6_proxy_select_ident(skb);
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break;
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}
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default:
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@@ -1189,7 +1194,6 @@ static ssize_t tun_get_user(struct tun_s
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skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
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}
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- skb_reset_network_header(skb);
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skb_probe_transport_header(skb, 0);
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rxhash = skb_get_hash(skb);
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--- a/include/net/ipv6.h
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+++ b/include/net/ipv6.h
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@@ -668,6 +668,8 @@ static inline int ipv6_addr_diff(const s
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return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));
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}
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+void ipv6_proxy_select_ident(struct sk_buff *skb);
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+
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int ip6_dst_hoplimit(struct dst_entry *dst);
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static inline int ip6_sk_dst_hoplimit(struct ipv6_pinfo *np, struct flowi6 *fl6,
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--- a/net/ipv6/output_core.c
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+++ b/net/ipv6/output_core.c
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@@ -3,11 +3,45 @@
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* not configured or static. These functions are needed by GSO/GRO implementation.
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*/
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#include <linux/export.h>
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+#include <net/ip.h>
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#include <net/ipv6.h>
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#include <net/ip6_fib.h>
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#include <net/addrconf.h>
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#include <net/secure_seq.h>
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+/* This function exists only for tap drivers that must support broken
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+ * clients requesting UFO without specifying an IPv6 fragment ID.
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+ *
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+ * This is similar to ipv6_select_ident() but we use an independent hash
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+ * seed to limit information leakage.
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+ *
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+ * The network header must be set before calling this.
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+ */
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+void ipv6_proxy_select_ident(struct sk_buff *skb)
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+{
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+ static u32 ip6_proxy_idents_hashrnd __read_mostly;
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+ struct in6_addr buf[2];
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+ struct in6_addr *addrs;
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+ u32 hash, id;
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+
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+ addrs = skb_header_pointer(skb,
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+ skb_network_offset(skb) +
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+ offsetof(struct ipv6hdr, saddr),
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+ sizeof(buf), buf);
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+ if (!addrs)
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+ return;
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+
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+ net_get_random_once(&ip6_proxy_idents_hashrnd,
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+ sizeof(ip6_proxy_idents_hashrnd));
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+
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+ hash = __ipv6_addr_jhash(&addrs[1], ip6_proxy_idents_hashrnd);
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+ hash = __ipv6_addr_jhash(&addrs[0], hash);
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+
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+ id = ip_idents_reserve(hash, 1);
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+ skb_shinfo(skb)->ip6_frag_id = htonl(id);
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+}
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+EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
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+
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int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
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{
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u16 offset = sizeof(struct ipv6hdr);
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