diff options
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 13 | ||||
| -rw-r--r-- | include/net/protocol.h | 7 | ||||
| -rw-r--r-- | net/dccp/ipv4.c | 1 | ||||
| -rw-r--r-- | net/ipv4/af_inet.c | 1 | ||||
| -rw-r--r-- | net/ipv4/icmp.c | 28 | ||||
| -rw-r--r-- | net/sctp/protocol.c | 1 |
6 files changed, 45 insertions, 6 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 0d71fa962d8a..c97932c88ea3 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -26,7 +26,18 @@ ip_no_pmtu_disc - INTEGER discarded. Outgoing frames are handled the same as in mode 1, implicitly setting IP_PMTUDISC_DONT on every created socket. - Possible values: 0-2 + Mode 3 is a hardend pmtu discover mode. The kernel will only + accept fragmentation-needed errors if the underlying protocol + can verify them besides a plain socket lookup. Current + protocols for which pmtu events will be honored are TCP, SCTP + and DCCP as they verify e.g. the sequence number or the + association. This mode should not be enabled globally but is + only intended to secure e.g. name servers in namespaces where + TCP path mtu must still work but path MTU information of other + protocols should be discarded. If enabled globally this mode + could break other protocols. + + Possible values: 0-3 Default: FALSE min_pmtu - INTEGER diff --git a/include/net/protocol.h b/include/net/protocol.h index fbf7676c9a02..0e5f8665d7fb 100644 --- a/include/net/protocol.h +++ b/include/net/protocol.h @@ -43,7 +43,12 @@ struct net_protocol { int (*handler)(struct sk_buff *skb); void (*err_handler)(struct sk_buff *skb, u32 info); unsigned int no_policy:1, - netns_ok:1; + netns_ok:1, + /* does the protocol do more stringent + * icmp tag validation than simple + * socket lookup? + */ + icmp_strict_tag_validation:1; }; #if IS_ENABLED(CONFIG_IPV6) diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index 88299c29101d..22b5d818b200 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -989,6 +989,7 @@ static const struct net_protocol dccp_v4_protocol = { .err_handler = dccp_v4_err, .no_policy = 1, .netns_ok = 1, + .icmp_strict_tag_validation = 1, }; static const struct proto_ops inet_dccp_ops = { diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 6268a4751e64..ecd2c3f245ce 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1545,6 +1545,7 @@ static const struct net_protocol tcp_protocol = { .err_handler = tcp_v4_err, .no_policy = 1, .netns_ok = 1, + .icmp_strict_tag_validation = 1, }; static const struct net_protocol udp_protocol = { diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index fb3c5637199d..0134663fdbce 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -668,6 +668,16 @@ static void icmp_socket_deliver(struct sk_buff *skb, u32 info) rcu_read_unlock(); } +static bool icmp_tag_validation(int proto) +{ + bool ok; + + rcu_read_lock(); + ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; + rcu_read_unlock(); + return ok; +} + /* * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and * ICMP_PARAMETERPROB. @@ -705,12 +715,22 @@ static void icmp_unreach(struct sk_buff *skb) case ICMP_PORT_UNREACH: break; case ICMP_FRAG_NEEDED: - if (net->ipv4.sysctl_ip_no_pmtu_disc == 2) { - goto out; - } else if (net->ipv4.sysctl_ip_no_pmtu_disc) { + /* for documentation of the ip_no_pmtu_disc + * values please see + * Documentation/networking/ip-sysctl.txt + */ + switch (net->ipv4.sysctl_ip_no_pmtu_disc) { + default: LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"), &iph->daddr); - } else { + break; + case 2: + goto out; + case 3: + if (!icmp_tag_validation(iph->protocol)) + goto out; + /* fall through */ + case 0: info = ntohs(icmph->un.frag.mtu); if (!info) goto out; diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index 34b7726bcd7f..7c161084f241 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -1030,6 +1030,7 @@ static const struct net_protocol sctp_protocol = { .err_handler = sctp_v4_err, .no_policy = 1, .netns_ok = 1, + .icmp_strict_tag_validation = 1, }; /* IPv4 address related functions. */ |