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ipv6: drop fragmented ndisc packets by default (RFC 6980)

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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>
This commit is contained in:
Hannes Frederic Sowa 2013-08-27 01:36:51 +02:00 committed by David S. Miller
parent a3a975b1df
commit b800c3b966
5 changed files with 35 additions and 0 deletions
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6
Documentation/networking/ip-sysctl.txt
View File

@ -1349,6 +1349,12 @@ mldv2_unsolicited_report_interval - INTEGER
MLDv2 report retransmit will take place.
Default: 1000 (1 second)
suppress_frag_ndisc - INTEGER
Control RFC 6980 (Security Implications of IPv6 Fragmentation
with IPv6 Neighbor Discovery) behavior:
1 - (default) discard fragmented neighbor discovery packets
0 - allow fragmented neighbor discovery packets
icmp/*:
ratelimit - INTEGER
Limit the maximal rates for sending ICMPv6 packets.

1
include/linux/ipv6.h
View File

@ -50,6 +50,7 @@ struct ipv6_devconf {
__s32 accept_dad;
__s32 force_tllao;
__s32 ndisc_notify;
__s32 suppress_frag_ndisc;
void *sysctl;
};

1
include/uapi/linux/ipv6.h
View File

@ -162,6 +162,7 @@ enum {
DEVCONF_NDISC_NOTIFY,
DEVCONF_MLDV1_UNSOLICITED_REPORT_INTERVAL,
DEVCONF_MLDV2_UNSOLICITED_REPORT_INTERVAL,
DEVCONF_SUPPRESS_FRAG_NDISC,
DEVCONF_MAX
};

10
net/ipv6/addrconf.c
View File

@ -204,6 +204,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
.accept_source_route = 0, /* we do not accept RH0 by default. */
.disable_ipv6 = 0,
.accept_dad = 1,
.suppress_frag_ndisc = 1,
};
static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
@ -241,6 +242,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
.accept_source_route = 0, /* we do not accept RH0 by default. */
.disable_ipv6 = 0,
.accept_dad = 1,
.suppress_frag_ndisc = 1,
};
/* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
@ -4188,6 +4190,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
array[DEVCONF_ACCEPT_DAD] = cnf->accept_dad;
array[DEVCONF_FORCE_TLLAO] = cnf->force_tllao;
array[DEVCONF_NDISC_NOTIFY] = cnf->ndisc_notify;
array[DEVCONF_SUPPRESS_FRAG_NDISC] = cnf->suppress_frag_ndisc;
}
static inline size_t inet6_ifla6_size(void)
@ -5001,6 +5004,13 @@ static struct addrconf_sysctl_table
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "suppress_frag_ndisc",
.data = &ipv6_devconf.suppress_frag_ndisc,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
/* sentinel */
}

17
net/ipv6/ndisc.c
View File

@ -1519,10 +1519,27 @@ static void pndisc_redo(struct sk_buff *skb)
kfree_skb(skb);
}
static bool ndisc_suppress_frag_ndisc(struct sk_buff *skb)
{
struct inet6_dev *idev = __in6_dev_get(skb->dev);
if (!idev)
return true;
if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED &&
idev->cnf.suppress_frag_ndisc) {
net_warn_ratelimited("Received fragmented ndisc packet. Carefully consider disabling suppress_frag_ndisc.\n");
return true;
}
return false;
}
int ndisc_rcv(struct sk_buff *skb)
{
struct nd_msg *msg;
if (ndisc_suppress_frag_ndisc(skb))
return 0;
if (skb_linearize(skb))
return 0;