From 1fd07f33c3ea2b4aa77426f13e8cb91d4f55af8f Mon Sep 17 00:00:00 2001 From: Andreas Roeseler Date: Sat, 26 Jun 2021 09:07:46 -0500 Subject: [PATCH] ipv6: ICMPV6: add response to ICMPV6 RFC 8335 PROBE messages This patch builds off of commit 2b246b2569cd2ac6ff700d0dce56b8bae29b1842 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 Reviewed-by: Willem de Bruijn Signed-off-by: David S. Miller --- include/net/icmp.h | 1 + net/ipv4/icmp.c | 63 ++++++++++++++++++++++++++++++---------------- net/ipv6/icmp.c | 21 +++++++++++++--- 3 files changed, 60 insertions(+), 25 deletions(-) diff --git a/include/net/icmp.h b/include/net/icmp.h index fd84adc47963..caddf4a59ad1 100644 --- a/include/net/icmp.h +++ b/include/net/icmp.h @@ -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 */ diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 0a57f1892e7e..c695d294a5df 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -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. diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index e8398ffb5e35..a7c31ab67c5d 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -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);