Currently the code to translate host side addresses and ports to guest side
addresses and ports, and vice versa, is scattered across the TCP code.
This includes both port redirection as controlled by the -t and -T options,
and our special case NAT controlled by the --no-map-gw option.
Gather this logic into fwd_nat_from_*() functions for each input
interface in fwd.c which take protocol and address information for the
initiating side and generates the pif and address information for the
forwarded side. This performs any NAT or port forwarding needed.
We create a flow_target() helper which applies those forwarding functions
as needed to automatically move a flow from INI to TGT state.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
tcp_listen_handler() uses the epoll reference for the listening socket
it handles, and also passes on one variant of it to
tcp_tap_conn_from_sock() and tcp_splice_conn_from_sock(). The latter
two functions only need a couple of specific fields from the
reference.
Pass those specific values instead of the whole reference, which
localises the handling of the listening (as opposed to accepted)
socket and its reference entirely within tcp_listen_handler().
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In tcp_splice_conn_from_sock(), the 'port' variable stores the source
port of the connection on the originating side. In tcp_splice_new(),
called directly from it, the 'port' parameter gives the _destination_
port of the originating connection and is then updated to the
destination port of the connection on the other side.
Similarly, in tcp_splice_conn_from_sock(), 's' is the fd of the
accetped socket (on side 0), whereas in tcp_splice_new(), 's' is the
fd of the connecting socket (side 1).
I, for one, find having the same variable name with different meanings
in such close proximity in the flow of control pretty confusing.
Alter the names for greater specificity and clarity.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Our allocation scheme for flow entries means there are some
non-obvious constraints on when what things can be done with an entry.
Add a big doc comment explaining the life cycle.
In addition, make a FLOW_START() macro to mark one of the important
transitions. This encourages correct usage, by making it natural to
only access the flow type specific structure after calling it. It
also logs that a new flow has been created, which is useful for
debugging.
We also add logging when a flow's lifecycle ends. This doesn't need a
new helper, because it can only happen either from flow_alloc_cancel()
or from the flow deferred handler.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
There are a number of places where we want to handle either a
sockaddr_in or a sockaddr_in6. In some of those we use a void *,
which works ok and matches some standard library interfaces, but
doesn't give a signature level hint that we're dealing with only
sockaddr_in or sockaddr_in6, not (say) sockaddr_un or another type of
socket address. Other places we use a sockaddr_storage, which also
works, but has the same problem in addition to allocating more on the
stack than we need to.
Introduce union sockaddr_inany to explictly handle this case: it has
variants for sockaddr_in and sockaddr_in6. Use it in a number of
places where it's easy to do so.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Currently connected TCP sockets have the same epoll type, whether they're
for a "tap" connection or a spliced connection. This means that
tcp_sock_handler() has to do a secondary check on the type of the
connection to call the right function. We can avoid this by adding a new
epoll type and dispatching directly to the right thing.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Currently TCP uses the 'flow' epoll_ref field for both connected
sockets and timers, which consists of just the index of the relevant
flow (connection).
This is just fine for timers, for while it obviously works, it's
subtly incomplete for sockets on spliced connections. In that case we
want to know which side of the connection the event is occurring on as
well as which connection. At present, we deduce that information by
looking at the actual fd, and comparing it to the fds of the sockets
on each side.
When we use the flow table for more things, we expect more cases where
something will need to know a specific side of a specific flow for an
event, but nothing more.
Therefore add a new 'flowside' epoll_ref field, with exactly that
information. We use it for TCP connected sockets. This allows us to
directly know the side for spliced connections. For "tap"
connections, it's pretty meaningless, since the side is always the
socket side. It still makes logical sense though, and it may become
important for future flow table work.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Newer versions of cppcheck (as of 2.12.0, at least) added a warning for
pointers which could be declared to point at const data, but aren't.
Based on that, make many pointers throughout the codebase const.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
tcp_sock_handler() handles both listening TCP sockets, and connected TCP
sockets, but what it needs to do in those cases has essentially nothing in
common. Therefore, give listening sockets their own epoll_type value and
dispatch directly to their own handler from the top level. Furthermore,
the two handlers need essentially entirely different information from the
reference: we re-(ab)used the index field in the tcp_epoll_ref to indicate
the port for the listening socket, but that's not the same meaning. So,
switch listening sockets to their own reference type which we can lay out
as we please. That lets us remove the listen and outbound fields from the
normal (connected) tcp_epoll_ref, reducing it to just the connection table
index.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In practical terms, passt doesn't benefit from the additional
protection offered by the AGPL over the GPL, because it's not
suitable to be executed over a computer network.
Further, restricting the distribution under the version 3 of the GPL
wouldn't provide any practical advantage either, as long as the passt
codebase is concerned, and might cause unnecessary compatibility
dilemmas.
Change licensing terms to the GNU General Public License Version 2,
or any later version, with written permission from all current and
past contributors, namely: myself, David Gibson, Laine Stump, Andrea
Bolognani, Paul Holzinger, Richard W.M. Jones, Chris Kuhn, Florian
Weimer, Giuseppe Scrivano, Stefan Hajnoczi, and Vasiliy Ulyanov.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Currently the epoll reference for tcp sockets includes a bit indicating
whether the socket maps to a spliced connection. However, the reference
also has the index of the connection structure which also indicates whether
it is spliced. We can therefore avoid the splice bit in the epoll_ref by
unifying the first part of the non-spliced and spliced handlers where we
look up the connection state.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In pasta mode, tcp_sock_init[46]() create separate sockets to listen for
spliced connections (these are bound to localhost) and non-spliced
connections (these are bound to the host address). This introduces a
subtle behavioural difference between pasta and passt: by default, pasta
will listen only on a single host address, whereas passt will listen on
all addresses (0.0.0.0 or ::). This also prevents us using some additional
optimizations that only work with the unspecified (0.0.0.0 or ::) address.
However, it turns out we don't need to do this. We can splice a connection
if and only if it originates from the loopback address. Currently we
ensure this by having the "spliced" listening sockets listening only on
loopback. Instead, defer the decision about whether to splice a connection
until after accept(), by checking if the connection was made from the
loopback address.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In tcp_sock_handler() we split off to handle spliced sockets before
checking anything else. However the first steps of the "new connection"
path for each case are the same: allocate a connection entry and accept()
the connection.
Remove this duplication by making tcp_conn_from_sock() handle both spliced
and non-spliced cases, with help from more specific tcp_tap_conn_from_sock
and tcp_splice_conn_from_sock functions for the later stages which differ.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
These two functions scan all the non-splced and spliced connections
respectively and perform timed updates on them. Avoid scanning the now
unified table twice, by having tcp_timer scan it once calling the
relevant per-connection function for each one.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
These two functions each step through non-spliced and spliced connections
respectively and clean up entries for closed connections. To avoid
scanning the connection table twice, we merge these into a single function
which scans the unified table and performs the appropriate sort of cleanup
action on each one.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Currently spliced and non-spliced connections are stored in completely
separate tables, so there are completely independent limits on the number
of spliced and non-spliced connections. This is a bit counter-intuitive.
More importantly, the fact that the tables are separate prevents us from
unifying some other logic between the two cases. So, merge these two
tables into one, using the 'c.spliced' common field to distinguish between
them when necessary.
For now we keep a common limit of 128k connections, whether they're spliced
or non-spliced, which means we save memory overall. If necessary we could
increase this to a 256k or higher total, which would cost memory but give
some more flexibility.
For now, the code paths which need to step through all extant connections
are still separate for the two cases, just skipping over entries which
aren't for them. We'll improve that in later patches.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This obvious include was omitted, which means that declarations in the
header weren't checked against definitions in the .c file. This shows up
an old declaration for a function that is now static, and a duplicate
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Implement a packet abstraction providing boundary and size checks
based on packet descriptors: packets stored in a buffer can be queued
into a pool (without storage of its own), and data can be retrieved
referring to an index in the pool, specifying offset and length.
Checks ensure data is not read outside the boundaries of buffer and
descriptors, and that packets added to a pool are within the buffer
range with valid offset and indices.
This implies a wider rework: usage of the "queueing" part of the
abstraction mostly affects tap_handler_{passt,pasta}() functions and
their callees, while the "fetching" part affects all the guest or tap
facing implementations: TCP, UDP, ICMP, ARP, NDP, DHCP and DHCPv6
handlers.
Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
We can't take for granted that the hard limit for open files is
big enough as to allow to delay closing sockets to a timer.
Store the value of RTLIMIT_NOFILE we set at start, and use it to
understand if we're approaching the limit with pending, spliced
TCP connections. If that's the case, close sockets right away as
soon as they're not needed, instead of deferring this task to a
timer.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Using events and flags instead of states makes the implementation
much more straightforward: actions are mostly centered on events
that occurred on the connection rather than states.
An example is given by the ESTABLISHED_SOCK_FIN_SENT and
FIN_WAIT_1_SOCK_FIN abominations: we don't actually care about
which side started closing the connection to handle closing of
connection halves.
Split out the spliced implementation, as it has very little in
common with the "regular" TCP path.
Refactor things here and there to improve clarity. Add helpers
to trace where resets and flag settings come from.
No functional changes intended.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
