kernel/net/ipv4/udp.c, branch linux-5.1.y

bpf: udp: Avoid calling reuseport's bpf_prog from udp_gro

2019-07-03T11:13:43Z

commit 257a525fe2e49584842c504a92c27097407f778f upstream. When the commit a6024562ffd7 ("udp: Add GRO functions to UDP socket") added udp[46]_lib_lookup_skb to the udp_gro code path, it broke the reuseport_select_sock() assumption that skb->data is pointing to the transport header. This patch follows an earlier __udp6_lib_err() fix by passing a NULL skb to avoid calling the reuseport's bpf_prog. Fixes: a6024562ffd7 ("udp: Add GRO functions to UDP socket") Cc: Tom Herbert Signed-off-by: Martin KaFai Lau Acked-by: Song Liu Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman

bpf: fix unconnected udp hooks

2019-07-03T11:13:43Z

commit 983695fa676568fc0fe5ddd995c7267aabc24632 upstream. Intention of cgroup bind/connect/sendmsg BPF hooks is to act transparently to applications as also stated in original motivation in 7828f20e3779 ("Merge branch 'bpf-cgroup-bind-connect'"). When recently integrating the latter two hooks into Cilium to enable host based load-balancing with Kubernetes, I ran into the issue that pods couldn't start up as DNS got broken. Kubernetes typically sets up DNS as a service and is thus subject to load-balancing. Upon further debugging, it turns out that the cgroupv2 sendmsg BPF hooks API is currently insufficient and thus not usable as-is for standard applications shipped with most distros. To break down the issue we ran into with a simple example: # cat /etc/resolv.conf nameserver 147.75.207.207 nameserver 147.75.207.208 For the purpose of a simple test, we set up above IPs as service IPs and transparently redirect traffic to a different DNS backend server for that node: # cilium service list ID Frontend Backend 1 147.75.207.207:53 1 => 8.8.8.8:53 2 147.75.207.208:53 1 => 8.8.8.8:53 The attached BPF program is basically selecting one of the backends if the service IP/port matches on the cgroup hook. DNS breaks here, because the hooks are not transparent enough to applications which have built-in msg_name address checks: # nslookup 1.1.1.1 ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53 ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.208#53 ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53 [...] ;; connection timed out; no servers could be reached # dig 1.1.1.1 ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53 ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.208#53 ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53 [...] ; <<>> DiG 9.11.3-1ubuntu1.7-Ubuntu <<>> 1.1.1.1 ;; global options: +cmd ;; connection timed out; no servers could be reached For comparison, if none of the service IPs is used, and we tell nslookup to use 8.8.8.8 directly it works just fine, of course: # nslookup 1.1.1.1 8.8.8.8 1.1.1.1.in-addr.arpa name = one.one.one.one. In order to fix this and thus act more transparent to the application, this needs reverse translation on recvmsg() side. A minimal fix for this API is to add similar recvmsg() hooks behind the BPF cgroups static key such that the program can track state and replace the current sockaddr_in{,6} with the original service IP. From BPF side, this basically tracks the service tuple plus socket cookie in an LRU map where the reverse NAT can then be retrieved via map value as one example. Side-note: the BPF cgroups static key should be converted to a per-hook static key in future. Same example after this fix: # cilium service list ID Frontend Backend 1 147.75.207.207:53 1 => 8.8.8.8:53 2 147.75.207.208:53 1 => 8.8.8.8:53 Lookups work fine now: # nslookup 1.1.1.1 1.1.1.1.in-addr.arpa name = one.one.one.one. Authoritative answers can be found from: # dig 1.1.1.1 ; <<>> DiG 9.11.3-1ubuntu1.7-Ubuntu <<>> 1.1.1.1 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 51550 ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;1.1.1.1. IN A ;; AUTHORITY SECTION: . 23426 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019052001 1800 900 604800 86400 ;; Query time: 17 msec ;; SERVER: 147.75.207.207#53(147.75.207.207) ;; WHEN: Tue May 21 12:59:38 UTC 2019 ;; MSG SIZE rcvd: 111 And from an actual packet level it shows that we're using the back end server when talking via 147.75.207.20{7,8} front end: # tcpdump -i any udp [...] 12:59:52.698732 IP foo.42011 > google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38) 12:59:52.698735 IP foo.42011 > google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38) 12:59:52.701208 IP google-public-dns-a.google.com.domain > foo.42011: 18803 1/0/0 PTR one.one.one.one. (67) 12:59:52.701208 IP google-public-dns-a.google.com.domain > foo.42011: 18803 1/0/0 PTR one.one.one.one. (67) [...] In order to be flexible and to have same semantics as in sendmsg BPF programs, we only allow return codes in [1,1] range. In the sendmsg case the program is called if msg->msg_name is present which can be the case in both, connected and unconnected UDP. The former only relies on the sockaddr_in{,6} passed via connect(2) if passed msg->msg_name was NULL. Therefore, on recvmsg side, we act in similar way to call into the BPF program whenever a non-NULL msg->msg_name was passed independent of sk->sk_state being TCP_ESTABLISHED or not. Note that for TCP case, the msg->msg_name is ignored in the regular recvmsg path and therefore not relevant. For the case of ip{,v6}_recv_error() paths, picked up via MSG_ERRQUEUE, the hook is not called. This is intentional as it aligns with the same semantics as in case of TCP cgroup BPF hooks right now. This might be better addressed in future through a different bpf_attach_type such that this case can be distinguished from the regular recvmsg paths, for example. Fixes: 1cedee13d25a ("bpf: Hooks for sys_sendmsg") Signed-off-by: Daniel Borkmann Acked-by: Andrey Ignatov Acked-by: Martin KaFai Lau Acked-by: Martynas Pumputis Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: Greg Kroah-Hartman

udp: only choose unbound UDP socket for multicast when not in a VRF

2019-06-11T10:19:12Z

[ Upstream commit 82ba25c6de200d7a9e9c970c998cdd6dfa8637ae ] By default, packets received in another VRF should not be passed to an unbound socket in the default VRF. This patch updates the IPv4 UDP multicast logic to match the unicast VRF logic (in compute_score()), as well as the IPv6 mcast logic (in __udp_v6_is_mcast_sock()). The particular case I noticed was DHCP discover packets going to the 255.255.255.255 address, which are handled by __udp4_lib_mcast_deliver(). The previous code meant that running multiple different DHCP server or relay agent instances across VRFs did not work correctly - any server/relay agent in the default VRF received DHCP discover packets for all other VRFs. Fixes: 6da5b0f027a8 ("net: ensure unbound datagram socket to be chosen when not in a VRF") Signed-off-by: Tim Beale Reviewed-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

udp: fix possible user after free in error handler

2019-02-23T00:05:11Z

Similar to the previous commit, this addresses the same issue for ipv4: use a single fetch operation and use the correct rcu annotation. Fixes: e7cc082455cb ("udp: Support for error handlers of tunnels with arbitrary destination port") Signed-off-by: Paolo Abeni Acked-by: Stefano Brivio Signed-off-by: David S. Miller

udp: add missing rehash callback to udplite

2019-01-17T23:01:08Z

After commit 4cdeeee9252a ("net: udp: prefer listeners bound to an address"), UDP-Lite only works when specifying a local address for the sockets. This is related to the problem addressed in the commit 719f835853a9 ("udp: add rehash on connect()"). Moreover, __udp4_lib_lookup() now looks for a socket immediately in the secondary hash table. The issue was found with LTP/network tests (UDP-Lite test-cases). Fixes: 4cdeeee9252a ("net: udp: prefer listeners bound to an address") Signed-off-by: Alexey Kodanev Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

udp: with udp_segment release on error path

2019-01-16T23:48:11Z

Failure __ip_append_data triggers udp_flush_pending_frames, but these tests happen later. The skb must be freed directly. Fixes: bec1f6f697362 ("udp: generate gso with UDP_SEGMENT") Reported-by: Eric Dumazet Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller

net: udp: prefer listeners bound to an address

2018-12-14T23:55:20Z

A relatively common use case is to have several IPs configured on a host, and have different listeners for each of them. We would like to add a "catch all" listener on addr_any, to match incoming connections not served by any of the listeners bound to a specific address. However, port-only lookups can match addr_any sockets when sockets listening on specific addresses are present if so_reuseport flag is set. This patch eliminates lookups into port-only hashtable, as lookups by (addr,port) tuple are easily available. In addition, compute_score() is tweaked to _not_ match addr_any sockets to specific addresses, as hash collisions could result in the unwanted behavior described above. Tested: the patch compiles; full test in the last patch in this patchset. Existing reuseport_* selftests also pass. Suggested-by: Eric Dumazet Signed-off-by: Peter Oskolkov Signed-off-by: David S. Miller

udp: fix jump label misuse

2018-11-17T07:01:56Z

The commit 60fb9567bf30 ("udp: implement complete book-keeping for encap_needed") introduced a severe misuse of jump label APIs, which syzbot, as reported by Eric, was able to exploit. When multiple sockets/process can concurrently request (and than disable) the udp encap, we need to track the activation counter with *_inc()/*_dec() jump label variants, or we can experience bad things at disable time. Fixes: 60fb9567bf30 ("udp: implement complete book-keeping for encap_needed") Reported-by: Eric Dumazet Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller

udp: Support for error handlers of tunnels with arbitrary destination port

2018-11-09T01:13:08Z

ICMP error handling is currently not possible for UDP tunnels not employing a receiving socket with local destination port matching the remote one, because we have no way to look them up. Add an err_handler tunnel encapsulation operation that can be exported by tunnels in order to pass the error to the protocol implementing the encapsulation. We can't easily use a lookup function as we did for VXLAN and GENEVE, as protocol error handlers, which would be in turn called by implementations of this new operation, handle the errors themselves, together with the tunnel lookup. Without a socket, we can't be sure which encapsulation error handler is the appropriate one: encapsulation handlers (the ones for FoU and GUE introduced in the next patch, e.g.) will need to check the new error codes returned by protocol handlers to figure out if errors match the given encapsulation, and, in turn, report this error back, so that we can try all of them in __udp{4,6}_lib_err_encap_no_sk() until we have a match. v2: - Name all arguments in err_handler prototypes (David Miller) Signed-off-by: Stefano Brivio Reviewed-by: Sabrina Dubroca Signed-off-by: David S. Miller

net: Convert protocol error handlers from void to int

2018-11-09T01:13:08Z

We'll need this to handle ICMP errors for tunnels without a sending socket (i.e. FoU and GUE). There, we might have to look up different types of IP tunnels, registered as network protocols, before we get a match, so we want this for the error handlers of IPPROTO_IPIP and IPPROTO_IPV6 in both inet_protos and inet6_protos. These error codes will be used in the next patch. For consistency, return sensible error codes in protocol error handlers whenever handlers can't handle errors because, even if valid, they don't match a protocol or any of its states. This has no effect on existing error handling paths. Signed-off-by: Stefano Brivio Reviewed-by: Sabrina Dubroca Signed-off-by: David S. Miller