ipv6: drop fragmented ndisc packets by default (RFC 6980)
This patch implements RFC6980: Drop fragmented ndisc packets by default. If a fragmented ndisc packet is received the user is informed that it is possible to disable the check. Cc: Fernando Gont <fernando@gont.com.ar> Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -1349,6 +1349,12 @@ mldv2_unsolicited_report_interval - INTEGER
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MLDv2 report retransmit will take place.
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Default: 1000 (1 second)
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suppress_frag_ndisc - INTEGER
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Control RFC 6980 (Security Implications of IPv6 Fragmentation
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with IPv6 Neighbor Discovery) behavior:
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1 - (default) discard fragmented neighbor discovery packets
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0 - allow fragmented neighbor discovery packets
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icmp/*:
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ratelimit - INTEGER
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Limit the maximal rates for sending ICMPv6 packets.
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@ -50,6 +50,7 @@ struct ipv6_devconf {
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__s32 accept_dad;
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__s32 force_tllao;
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__s32 ndisc_notify;
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__s32 suppress_frag_ndisc;
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void *sysctl;
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};
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@ -162,6 +162,7 @@ enum {
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DEVCONF_NDISC_NOTIFY,
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DEVCONF_MLDV1_UNSOLICITED_REPORT_INTERVAL,
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DEVCONF_MLDV2_UNSOLICITED_REPORT_INTERVAL,
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DEVCONF_SUPPRESS_FRAG_NDISC,
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DEVCONF_MAX
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};
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@ -204,6 +204,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
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.accept_source_route = 0, /* we do not accept RH0 by default. */
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.disable_ipv6 = 0,
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.accept_dad = 1,
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.suppress_frag_ndisc = 1,
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};
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static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
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@ -241,6 +242,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
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.accept_source_route = 0, /* we do not accept RH0 by default. */
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.disable_ipv6 = 0,
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.accept_dad = 1,
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.suppress_frag_ndisc = 1,
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};
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/* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
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@ -4188,6 +4190,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
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array[DEVCONF_ACCEPT_DAD] = cnf->accept_dad;
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array[DEVCONF_FORCE_TLLAO] = cnf->force_tllao;
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array[DEVCONF_NDISC_NOTIFY] = cnf->ndisc_notify;
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array[DEVCONF_SUPPRESS_FRAG_NDISC] = cnf->suppress_frag_ndisc;
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}
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static inline size_t inet6_ifla6_size(void)
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@ -5001,6 +5004,13 @@ static struct addrconf_sysctl_table
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{
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.procname = "suppress_frag_ndisc",
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.data = &ipv6_devconf.suppress_frag_ndisc,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{
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/* sentinel */
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}
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@ -1519,10 +1519,27 @@ static void pndisc_redo(struct sk_buff *skb)
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kfree_skb(skb);
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}
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static bool ndisc_suppress_frag_ndisc(struct sk_buff *skb)
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{
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struct inet6_dev *idev = __in6_dev_get(skb->dev);
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if (!idev)
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return true;
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if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED &&
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idev->cnf.suppress_frag_ndisc) {
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net_warn_ratelimited("Received fragmented ndisc packet. Carefully consider disabling suppress_frag_ndisc.\n");
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return true;
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}
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return false;
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}
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int ndisc_rcv(struct sk_buff *skb)
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{
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struct nd_msg *msg;
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if (ndisc_suppress_frag_ndisc(skb))
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return 0;
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if (skb_linearize(skb))
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return 0;
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