<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/net/ipv4/udp.c, branch v5.3-rc7</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>udp: Fix typo in net/ipv4/udp.c</title>
<updated>2019-07-18T18:49:46+00:00</updated>
<author>
<name>Su Yanjun</name>
<email>suyj.fnst@cn.fujitsu.com</email>
</author>
<published>2019-07-18T02:19:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=666a3d6e1e6b78df34f59e6c0b8907aa3c8dbb2e'/>
<id>666a3d6e1e6b78df34f59e6c0b8907aa3c8dbb2e</id>
<content type='text'>
Signed-off-by: Su Yanjun &lt;suyj.fnst@cn.fujitsu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Su Yanjun &lt;suyj.fnst@cn.fujitsu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: remove unused parameter from skb_checksum_try_convert</title>
<updated>2019-07-05T22:30:36+00:00</updated>
<author>
<name>Li RongQing</name>
<email>lirongqing@baidu.com</email>
</author>
<published>2019-07-04T09:03:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e4aa33ad595936391f7356f25c0c839011f14ead'/>
<id>e4aa33ad595936391f7356f25c0c839011f14ead</id>
<content type='text'>
the check parameter is never used

Signed-off-by: Li RongQing &lt;lirongqing@baidu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
the check parameter is never used

Signed-off-by: Li RongQing &lt;lirongqing@baidu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net</title>
<updated>2019-06-18T03:20:36+00:00</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2019-06-18T02:48:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=13091aa30535b719e269f20a7bc34002bf5afae5'/>
<id>13091aa30535b719e269f20a7bc34002bf5afae5</id>
<content type='text'>
Honestly all the conflicts were simple overlapping changes,
nothing really interesting to report.

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Honestly all the conflicts were simple overlapping changes,
nothing really interesting to report.

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>udp: Remove unused variable/function (exact_dif)</title>
<updated>2019-06-15T02:52:07+00:00</updated>
<author>
<name>Tim Beale</name>
<email>timbeale@catalyst.net.nz</email>
</author>
<published>2019-06-14T04:41:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f48d2ccee1ba3b2bdb0901d4e5bb3cfe2edd7b36'/>
<id>f48d2ccee1ba3b2bdb0901d4e5bb3cfe2edd7b36</id>
<content type='text'>
This was originally passed through to the VRF logic in compute_score().
But that logic has now been replaced by udp_sk_bound_dev_eq() and so
this code is no longer used or needed.

Signed-off-by: Tim Beale &lt;timbeale@catalyst.net.nz&gt;
Reviewed-by: David Ahern &lt;dsahern@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This was originally passed through to the VRF logic in compute_score().
But that logic has now been replaced by udp_sk_bound_dev_eq() and so
this code is no longer used or needed.

Signed-off-by: Tim Beale &lt;timbeale@catalyst.net.nz&gt;
Reviewed-by: David Ahern &lt;dsahern@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>udp: Remove unused parameter (exact_dif)</title>
<updated>2019-06-15T02:52:07+00:00</updated>
<author>
<name>Tim Beale</name>
<email>timbeale@catalyst.net.nz</email>
</author>
<published>2019-06-14T04:41:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=735453730a05391b4be97ad408b3bef07df13fe7'/>
<id>735453730a05391b4be97ad408b3bef07df13fe7</id>
<content type='text'>
Originally this was used by the VRF logic in compute_score(), but that
was later replaced by udp_sk_bound_dev_eq() and the parameter became
unused.

Note this change adds an 'unused variable' compiler warning that will be
removed in the next patch (I've split the removal in two to make review
slightly easier).

Signed-off-by: Tim Beale &lt;timbeale@catalyst.net.nz&gt;
Reviewed-by: David Ahern &lt;dsahern@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Originally this was used by the VRF logic in compute_score(), but that
was later replaced by udp_sk_bound_dev_eq() and the parameter became
unused.

Note this change adds an 'unused variable' compiler warning that will be
removed in the next patch (I've split the removal in two to make review
slightly easier).

Signed-off-by: Tim Beale &lt;timbeale@catalyst.net.nz&gt;
Reviewed-by: David Ahern &lt;dsahern@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf</title>
<updated>2019-06-07T21:46:47+00:00</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2019-06-07T21:46:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=38e406f600a2b6dca9c262603f6e2a31cfb792b8'/>
<id>38e406f600a2b6dca9c262603f6e2a31cfb792b8</id>
<content type='text'>
Daniel Borkmann says:

====================
pull-request: bpf 2019-06-07

The following pull-request contains BPF updates for your *net* tree.

The main changes are:

1) Fix several bugs in riscv64 JIT code emission which forgot to clear high
   32-bits for alu32 ops, from Björn and Luke with selftests covering all
   relevant BPF alu ops from Björn and Jiong.

2) Two fixes for UDP BPF reuseport that avoid calling the program in case of
   __udp6_lib_err and UDP GRO which broke reuseport_select_sock() assumption
   that skb-&gt;data is pointing to transport header, from Martin.

3) Two fixes for BPF sockmap: a use-after-free from sleep in psock's backlog
   workqueue, and a missing restore of sk_write_space when psock gets dropped,
   from Jakub and John.

4) Fix unconnected UDP sendmsg hook API which is insufficient as-is since it
   breaks standard applications like DNS if reverse NAT is not performed upon
   receive, from Daniel.

5) Fix an out-of-bounds read in __bpf_skc_lookup which in case of AF_INET6
   fails to verify that the length of the tuple is long enough, from Lorenz.

6) Fix libbpf's libbpf__probe_raw_btf to return an fd instead of 0/1 (for
   {un,}successful probe) as that is expected to be propagated as an fd to
   load_sk_storage_btf() and thus closing the wrong descriptor otherwise,
   from Michal.

7) Fix bpftool's JSON output for the case when a lookup fails, from Krzesimir.

8) Minor misc fixes in docs, samples and selftests, from various others.
====================

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Daniel Borkmann says:

====================
pull-request: bpf 2019-06-07

The following pull-request contains BPF updates for your *net* tree.

The main changes are:

1) Fix several bugs in riscv64 JIT code emission which forgot to clear high
   32-bits for alu32 ops, from Björn and Luke with selftests covering all
   relevant BPF alu ops from Björn and Jiong.

2) Two fixes for UDP BPF reuseport that avoid calling the program in case of
   __udp6_lib_err and UDP GRO which broke reuseport_select_sock() assumption
   that skb-&gt;data is pointing to transport header, from Martin.

3) Two fixes for BPF sockmap: a use-after-free from sleep in psock's backlog
   workqueue, and a missing restore of sk_write_space when psock gets dropped,
   from Jakub and John.

4) Fix unconnected UDP sendmsg hook API which is insufficient as-is since it
   breaks standard applications like DNS if reverse NAT is not performed upon
   receive, from Daniel.

5) Fix an out-of-bounds read in __bpf_skc_lookup which in case of AF_INET6
   fails to verify that the length of the tuple is long enough, from Lorenz.

6) Fix libbpf's libbpf__probe_raw_btf to return an fd instead of 0/1 (for
   {un,}successful probe) as that is expected to be propagated as an fd to
   load_sk_storage_btf() and thus closing the wrong descriptor otherwise,
   from Michal.

7) Fix bpftool's JSON output for the case when a lookup fails, from Krzesimir.

8) Minor misc fixes in docs, samples and selftests, from various others.
====================

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net</title>
<updated>2019-06-07T18:00:14+00:00</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2019-06-07T18:00:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a6cdeeb16bff89c8486324f53577db058cbe81ba'/>
<id>a6cdeeb16bff89c8486324f53577db058cbe81ba</id>
<content type='text'>
Some ISDN files that got removed in net-next had some changes
done in mainline, take the removals.

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Some ISDN files that got removed in net-next had some changes
done in mainline, take the removals.

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net</title>
<updated>2019-06-07T16:29:14+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-06-07T16:29:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=1e1d926369545ea09c98c6c7f5d109aa4ee0cd0b'/>
<id>1e1d926369545ea09c98c6c7f5d109aa4ee0cd0b</id>
<content type='text'>
Pull networking fixes from David Miller:

 1) Free AF_PACKET po-&gt;rollover properly, from Willem de Bruijn.

 2) Read SFP eeprom in max 16 byte increments to avoid problems with
    some SFP modules, from Russell King.

 3) Fix UDP socket lookup wrt. VRF, from Tim Beale.

 4) Handle route invalidation properly in s390 qeth driver, from Julian
    Wiedmann.

 5) Memory leak on unload in RDS, from Zhu Yanjun.

 6) sctp_process_init leak, from Neil HOrman.

 7) Fix fib_rules rule insertion semantic change that broke Android,
    from Hangbin Liu.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (33 commits)
  pktgen: do not sleep with the thread lock held.
  net: mvpp2: Use strscpy to handle stat strings
  net: rds: fix memory leak in rds_ib_flush_mr_pool
  ipv6: fix EFAULT on sendto with icmpv6 and hdrincl
  ipv6: use READ_ONCE() for inet-&gt;hdrincl as in ipv4
  Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"
  net: aquantia: fix wol configuration not applied sometimes
  ethtool: fix potential userspace buffer overflow
  Fix memory leak in sctp_process_init
  net: rds: fix memory leak when unload rds_rdma
  ipv6: fix the check before getting the cookie in rt6_get_cookie
  ipv4: not do cache for local delivery if bc_forwarding is enabled
  s390/qeth: handle error when updating TX queue count
  s390/qeth: fix VLAN attribute in bridge_hostnotify udev event
  s390/qeth: check dst entry before use
  s390/qeth: handle limited IPv4 broadcast in L3 TX path
  net: fix indirect calls helpers for ptype list hooks.
  net: ipvlan: Fix ipvlan device tso disabled while NETIF_F_IP_CSUM is set
  udp: only choose unbound UDP socket for multicast when not in a VRF
  net/tls: replace the sleeping lock around RX resync with a bit lock
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull networking fixes from David Miller:

 1) Free AF_PACKET po-&gt;rollover properly, from Willem de Bruijn.

 2) Read SFP eeprom in max 16 byte increments to avoid problems with
    some SFP modules, from Russell King.

 3) Fix UDP socket lookup wrt. VRF, from Tim Beale.

 4) Handle route invalidation properly in s390 qeth driver, from Julian
    Wiedmann.

 5) Memory leak on unload in RDS, from Zhu Yanjun.

 6) sctp_process_init leak, from Neil HOrman.

 7) Fix fib_rules rule insertion semantic change that broke Android,
    from Hangbin Liu.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (33 commits)
  pktgen: do not sleep with the thread lock held.
  net: mvpp2: Use strscpy to handle stat strings
  net: rds: fix memory leak in rds_ib_flush_mr_pool
  ipv6: fix EFAULT on sendto with icmpv6 and hdrincl
  ipv6: use READ_ONCE() for inet-&gt;hdrincl as in ipv4
  Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"
  net: aquantia: fix wol configuration not applied sometimes
  ethtool: fix potential userspace buffer overflow
  Fix memory leak in sctp_process_init
  net: rds: fix memory leak when unload rds_rdma
  ipv6: fix the check before getting the cookie in rt6_get_cookie
  ipv4: not do cache for local delivery if bc_forwarding is enabled
  s390/qeth: handle error when updating TX queue count
  s390/qeth: fix VLAN attribute in bridge_hostnotify udev event
  s390/qeth: check dst entry before use
  s390/qeth: handle limited IPv4 broadcast in L3 TX path
  net: fix indirect calls helpers for ptype list hooks.
  net: ipvlan: Fix ipvlan device tso disabled while NETIF_F_IP_CSUM is set
  udp: only choose unbound UDP socket for multicast when not in a VRF
  net/tls: replace the sleeping lock around RX resync with a bit lock
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: fix unconnected udp hooks</title>
<updated>2019-06-06T23:53:12+00:00</updated>
<author>
<name>Daniel Borkmann</name>
<email>daniel@iogearbox.net</email>
</author>
<published>2019-06-06T23:48:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=983695fa676568fc0fe5ddd995c7267aabc24632'/>
<id>983695fa676568fc0fe5ddd995c7267aabc24632</id>
<content type='text'>
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 =&gt; 8.8.8.8:53
  2    147.75.207.208:53   1 =&gt; 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
  [...]

  ; &lt;&lt;&gt;&gt; DiG 9.11.3-1ubuntu1.7-Ubuntu &lt;&lt;&gt;&gt; 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 =&gt; 8.8.8.8:53
  2    147.75.207.208:53   1 =&gt; 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

  ; &lt;&lt;&gt;&gt; DiG 9.11.3-1ubuntu1.7-Ubuntu &lt;&lt;&gt;&gt; 1.1.1.1
  ;; global options: +cmd
  ;; Got answer:
  ;; -&gt;&gt;HEADER&lt;&lt;- 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 &gt; google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38)
  12:59:52.698735 IP foo.42011 &gt; 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 &gt; foo.42011: 18803 1/0/0 PTR one.one.one.one. (67)
  12:59:52.701208 IP google-public-dns-a.google.com.domain &gt; 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-&gt;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-&gt;msg_name was NULL. Therefore, on recvmsg side, we act in similar
way to call into the BPF program whenever a non-NULL msg-&gt;msg_name was
passed independent of sk-&gt;sk_state being TCP_ESTABLISHED or not. Note
that for TCP case, the msg-&gt;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 &lt;daniel@iogearbox.net&gt;
Acked-by: Andrey Ignatov &lt;rdna@fb.com&gt;
Acked-by: Martin KaFai Lau &lt;kafai@fb.com&gt;
Acked-by: Martynas Pumputis &lt;m@lambda.lt&gt;
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 =&gt; 8.8.8.8:53
  2    147.75.207.208:53   1 =&gt; 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
  [...]

  ; &lt;&lt;&gt;&gt; DiG 9.11.3-1ubuntu1.7-Ubuntu &lt;&lt;&gt;&gt; 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 =&gt; 8.8.8.8:53
  2    147.75.207.208:53   1 =&gt; 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

  ; &lt;&lt;&gt;&gt; DiG 9.11.3-1ubuntu1.7-Ubuntu &lt;&lt;&gt;&gt; 1.1.1.1
  ;; global options: +cmd
  ;; Got answer:
  ;; -&gt;&gt;HEADER&lt;&lt;- 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 &gt; google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38)
  12:59:52.698735 IP foo.42011 &gt; 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 &gt; foo.42011: 18803 1/0/0 PTR one.one.one.one. (67)
  12:59:52.701208 IP google-public-dns-a.google.com.domain &gt; 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-&gt;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-&gt;msg_name was NULL. Therefore, on recvmsg side, we act in similar
way to call into the BPF program whenever a non-NULL msg-&gt;msg_name was
passed independent of sk-&gt;sk_state being TCP_ESTABLISHED or not. Note
that for TCP case, the msg-&gt;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 &lt;daniel@iogearbox.net&gt;
Acked-by: Andrey Ignatov &lt;rdna@fb.com&gt;
Acked-by: Martin KaFai Lau &lt;kafai@fb.com&gt;
Acked-by: Martynas Pumputis &lt;m@lambda.lt&gt;
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: ipv4: drop unneeded likely() call around IS_ERR()</title>
<updated>2019-06-05T23:57:23+00:00</updated>
<author>
<name>Enrico Weigelt</name>
<email>info@metux.net</email>
</author>
<published>2019-06-05T21:09:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=88e235b80c2ad9117e153f2651857142d2d65db9'/>
<id>88e235b80c2ad9117e153f2651857142d2d65db9</id>
<content type='text'>
IS_ERR() already calls unlikely(), so this extra unlikely() call
around IS_ERR() is not needed.

Signed-off-by: Enrico Weigelt &lt;info@metux.net&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
IS_ERR() already calls unlikely(), so this extra unlikely() call
around IS_ERR() is not needed.

Signed-off-by: Enrico Weigelt &lt;info@metux.net&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
</feed>
