udp: Find or create flows for datagrams from tap interface

Currently we create flows for datagrams from socket interfaces, and use
them to direct "spliced" (socket to socket) datagrams.  We don't yet
match datagrams from the tap interface to existing flows, nor create new
flows for them.  Add that functionality, matching datagrams from tap to
existing flows when they exist, or creating new ones.

As with spliced flows, when creating a new flow from tap to socket, we
create a new connected socket to receive reply datagrams attached to that
flow specifically. We extend udp_flow_sock_handler() to handle reply
packets bound for tap rather than another socket.

For non-obvious reasons (perhaps increased stack usage?), this caused
a failure for me when running under valgrind, because valgrind invoked
rt_sigreturn which is not in our seccomp filter.  Since we already
allow rt_sigaction and others in the valgrind target, it seems
reasonable to add rt_sigreturn as well.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 92cbd5a..bd504d2 100644
--- a/Makefile
+++ b/Makefile
@@ -128,7 +128,7 @@ qrap: $(QRAP_SRCS) passt.h
 	$(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) $(QRAP_SRCS) -o qrap $(LDFLAGS)
 
 valgrind: EXTRA_SYSCALLS += rt_sigprocmask rt_sigtimedwait rt_sigaction	\
-			    getpid gettid kill clock_gettime mmap	\
+			    rt_sigreturn getpid gettid kill clock_gettime mmap \
 			    munmap open unlink gettimeofday futex
 valgrind: FLAGS += -g -DVALGRIND
 valgrind: all