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ipv6: ICMPV6: add response to ICMPV6 RFC 8335 PROBE messages 

This patch builds off of commit 2b246b2569
and adds functionality to respond to ICMPV6 PROBE requests.

Add icmp_build_probe function to construct PROBE requests for both
ICMPV4 and ICMPV6.

Modify icmpv6_rcv to detect ICMPV6 PROBE messages and call the
icmpv6_echo_reply handler.

Modify icmpv6_echo_reply to build a PROBE response message based on the
queried interface.

This patch has been tested using a branch of the iputils git repo which can
be found here: https://github.com/Juniper-Clinic-2020/iputils/tree/probe-request

Signed-off-by: Andreas Roeseler <andreas.a.roeseler@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Andreas Roeseler 2021-06-26 09:07:46 -05:00 committed by David S. Miller
parent 83300c69e7
commit 1fd07f33c3
3 changed files with 60 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/icmp.h
View File

@ -57,5 +57,6 @@ int icmp_rcv(struct sk_buff *skb);
int icmp_err(struct sk_buff *skb, u32 info);
int icmp_init(void);
void icmp_out_count(struct net *net, unsigned char type);
bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr);
#endif /* _ICMP_H */

63
net/ipv4/icmp.c
View File

@ -993,14 +993,8 @@ static bool icmp_redirect(struct sk_buff *skb)
static bool icmp_echo(struct sk_buff *skb)
{
struct icmp_ext_hdr *ext_hdr, _ext_hdr;
struct icmp_ext_echo_iio *iio, _iio;
struct icmp_bxm icmp_param;
struct net_device *dev;
char buff[IFNAMSIZ];
struct net *net;
u16 ident_len;
u8 status;
net = dev_net(skb_dst(skb)->dev);
/* should there be an ICMP stat for ignored echos? */
@ -1013,20 +1007,46 @@ static bool icmp_echo(struct sk_buff *skb)
icmp_param.data_len = skb->len;
icmp_param.head_len = sizeof(struct icmphdr);
if (icmp_param.data.icmph.type == ICMP_ECHO) {
if (icmp_param.data.icmph.type == ICMP_ECHO)
icmp_param.data.icmph.type = ICMP_ECHOREPLY;
goto send_reply;
}
if (!net->ipv4.sysctl_icmp_echo_enable_probe)
else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
return true;
icmp_reply(&icmp_param, skb);
return true;
}
/* Helper for icmp_echo and icmpv6_echo_reply.
* Searches for net_device that matches PROBE interface identifier
* and builds PROBE reply message in icmphdr.
*
* Returns false if PROBE responses are disabled via sysctl
*/
bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
{
struct icmp_ext_hdr *ext_hdr, _ext_hdr;
struct icmp_ext_echo_iio *iio, _iio;
struct net *net = dev_net(skb->dev);
struct net_device *dev;
char buff[IFNAMSIZ];
u16 ident_len;
u8 status;
if (!net->ipv4.sysctl_icmp_echo_enable_probe)
return false;
/* We currently only support probing interfaces on the proxy node
* Check to ensure L-bit is set
*/
if (!(ntohs(icmp_param.data.icmph.un.echo.sequence) & 1))
return true;
if (!(ntohs(icmphdr->un.echo.sequence) & 1))
return false;
/* Clear status bits in reply message */
icmp_param.data.icmph.un.echo.sequence &= htons(0xFF00);
icmp_param.data.icmph.type = ICMP_EXT_ECHOREPLY;
icmphdr->un.echo.sequence &= htons(0xFF00);
if (icmphdr->type == ICMP_EXT_ECHO)
icmphdr->type = ICMP_EXT_ECHOREPLY;
else
icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
/* Size of iio is class_type dependent.
* Only check header here and assign length based on ctype in the switch statement
@ -1087,8 +1107,8 @@ static bool icmp_echo(struct sk_buff *skb)
goto send_mal_query;
}
if (!dev) {
icmp_param.data.icmph.code = ICMP_EXT_CODE_NO_IF;
goto send_reply;
icmphdr->code = ICMP_EXT_CODE_NO_IF;
return true;
}
/* Fill bits in reply message */
if (dev->flags & IFF_UP)
@ -1098,14 +1118,13 @@ static bool icmp_echo(struct sk_buff *skb)
if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
status |= ICMP_EXT_ECHOREPLY_IPV6;
dev_put(dev);
icmp_param.data.icmph.un.echo.sequence |= htons(status);
send_reply:
icmp_reply(&icmp_param, skb);
return true;
icmphdr->un.echo.sequence |= htons(status);
return true;
send_mal_query:
icmp_param.data.icmph.code = ICMP_EXT_CODE_MAL_QUERY;
goto send_reply;
icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
return true;
}
EXPORT_SYMBOL_GPL(icmp_build_probe);
/*
* Handle ICMP Timestamp requests.

21
net/ipv6/icmp.c
View File

@ -725,6 +725,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
struct ipcm6_cookie ipc6;
u32 mark = IP6_REPLY_MARK(net, skb->mark);
bool acast;
u8 type;
if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) &&
net->ipv6.sysctl.icmpv6_echo_ignore_multicast)
@ -740,8 +741,13 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
!(net->ipv6.sysctl.anycast_src_echo_reply && acast))
saddr = NULL;
if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST)
type = ICMPV6_EXT_ECHO_REPLY;
else
type = ICMPV6_ECHO_REPLY;
memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
tmp_hdr.icmp6_type = ICMPV6_ECHO_REPLY;
tmp_hdr.icmp6_type = type;
memset(&fl6, 0, sizeof(fl6));
if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_ICMPV6_ECHO_REPLIES)
@ -752,7 +758,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
if (saddr)
fl6.saddr = *saddr;
fl6.flowi6_oif = icmp6_iif(skb);
fl6.fl6_icmp_type = ICMPV6_ECHO_REPLY;
fl6.fl6_icmp_type = type;
fl6.flowi6_mark = mark;
fl6.flowi6_uid = sock_net_uid(net, NULL);
security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6));
@ -783,13 +789,17 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
msg.skb = skb;
msg.offset = 0;
msg.type = ICMPV6_ECHO_REPLY;
msg.type = type;
ipcm6_init_sk(&ipc6, np);
ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
ipc6.tclass = ipv6_get_dsfield(ipv6_hdr(skb));
ipc6.sockc.mark = mark;
if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST)
if (!icmp_build_probe(skb, (struct icmphdr *)&tmp_hdr))
goto out_dst_release;
if (ip6_append_data(sk, icmpv6_getfrag, &msg,
skb->len + sizeof(struct icmp6hdr),
sizeof(struct icmp6hdr), &ipc6, &fl6,
@ -911,6 +921,11 @@ static int icmpv6_rcv(struct sk_buff *skb)
if (!net->ipv6.sysctl.icmpv6_echo_ignore_all)
icmpv6_echo_reply(skb);
break;
case ICMPV6_EXT_ECHO_REQUEST:
if (!net->ipv6.sysctl.icmpv6_echo_ignore_all &&
net->ipv4.sysctl_icmp_echo_enable_probe)
icmpv6_echo_reply(skb);
break;
case ICMPV6_ECHO_REPLY:
success = ping_rcv(skb);