linux/net/rxrpc
Willem de Bruijn c247f0534c ip: fix error queue empty skb handling
When reading from the error queue, msg_name and msg_control are only
populated for some errors. A new exception for empty timestamp skbs
added a false positive on icmp errors without payload.

`traceroute -M udpconn` only displayed gateways that return payload
with the icmp error: the embedded network headers are pulled before
sock_queue_err_skb, leaving an skb with skb->len == 0 otherwise.

Fix this regression by refining when msg_name and msg_control
branches are taken. The solutions for the two fields are independent.

msg_name only makes sense for errors that configure serr->port and
serr->addr_offset. Test the first instead of skb->len. This also fixes
another issue. saddr could hold the wrong data, as serr->addr_offset
is not initialized  in some code paths, pointing to the start of the
network header. It is only valid when serr->port is set (non-zero).

msg_control support differs between IPv4 and IPv6. IPv4 only honors
requests for ICMP and timestamps with SOF_TIMESTAMPING_OPT_CMSG. The
skb->len test can simply be removed, because skb->dev is also tested
and never true for empty skbs. IPv6 honors requests for all errors
aside from local errors and timestamps on empty skbs.

In both cases, make the policy more explicit by moving this logic to
a new function that decides whether to process msg_control and that
optionally prepares the necessary fields in skb->cb[]. After this
change, the IPv4 and IPv6 paths are more similar.

The last case is rxrpc. Here, simply refine to only match timestamps.

Fixes: 49ca0d8bfa ("net-timestamp: no-payload option")

Reported-by: Jan Niehusmann <jan@gondor.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>

----

Changes
  v1->v2
  - fix local origin test inversion in ip6_datagram_support_cmsg
  - make v4 and v6 code paths more similar by introducing analogous
    ipv4_datagram_support_cmsg
  - fix compile bug in rxrpc
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-08 23:01:54 -04:00
..
af_rxrpc.c af_rxrpc: Add sysctls for configuring RxRPC parameters 2014-02-26 17:25:06 +00:00
ar-accept.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
ar-ack.c rxrpc: don't multiply with HZ twice 2015-03-01 13:40:23 -05:00
ar-call.c af_rxrpc: Keep rxrpc_call pointers in a hashtable 2014-03-04 10:36:53 +00:00
ar-connection.c af_rxrpc: Add sysctls for configuring RxRPC parameters 2014-02-26 17:25:06 +00:00
ar-connevent.c rxrpc: Kill set but unused variable 'sp' in rxrpc_process_connection() 2011-05-19 18:35:58 -04:00
ar-error.c ip: fix error queue empty skb handling 2015-03-08 23:01:54 -04:00
ar-input.c net: remove dead code after sk_data_ready change 2014-08-22 21:08:50 -07:00
ar-internal.h net: Fix use after free by removing length arg from sk_data_ready callbacks. 2014-04-11 16:15:36 -04:00
ar-key.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2014-10-12 10:13:55 -04:00
ar-local.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
ar-output.c rxrpc: make the users of rxrpc_kernel_send_data() set kvec-backed msg_iter properly 2015-02-04 01:34:14 -05:00
ar-peer.c net/rxrpc/ar-peer.c: remove invalid reference to list iterator variable 2012-07-09 15:24:33 -07:00
ar-proc.c
ar-recvmsg.c net: Add and use skb_copy_datagram_msg() helper. 2014-11-05 16:46:40 -05:00
ar-security.c
ar-skbuff.c af_rxrpc: Improve ACK production 2014-02-26 17:25:07 +00:00
ar-transport.c af_rxrpc: Add sysctls for configuring RxRPC parameters 2014-02-26 17:25:06 +00:00
Kconfig net/rxrpc: remove depends on CONFIG_EXPERIMENTAL 2013-01-11 11:40:02 -08:00
Makefile af_rxrpc: Add sysctls for configuring RxRPC parameters 2014-02-26 17:25:06 +00:00
rxkad.c net: cleanup unsigned to unsigned int 2012-04-15 12:44:40 -04:00
sysctl.c af_rxrpc: Expose more RxRPC parameters via sysctls 2014-02-26 17:25:07 +00:00