2021-03-17 09:57:41 +00:00
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#ifndef TCP_H
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#define TCP_H
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struct ctx;
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passt: New design and implementation with native Layer 4 sockets
This is a reimplementation, partially building on the earlier draft,
that uses L4 sockets (SOCK_DGRAM, SOCK_STREAM) instead of SOCK_RAW,
providing L4-L2 translation functionality without requiring any
security capability.
Conceptually, this follows the design presented at:
https://gitlab.com/abologna/kubevirt-and-kvm/-/blob/master/Networking.md
The most significant novelty here comes from TCP and UDP translation
layers. In particular, the TCP state and translation logic follows
the intent of being minimalistic, without reimplementing a full TCP
stack in either direction, and synchronising as much as possible the
TCP dynamic and flows between guest and host kernel.
Another important introduction concerns addressing, port translation
and forwarding. The Layer 4 implementations now attempt to bind on
all unbound ports, in order to forward connections in a transparent
way.
While at it:
- the qemu 'tap' back-end can't be used as-is by qrap anymore,
because of explicit checks now introduced in qemu to ensure that
the corresponding file descriptor is actually a tap device. For
this reason, qrap now operates on a 'socket' back-end type,
accounting for and building the additional header reporting
frame length
- provide a demo script that sets up namespaces, addresses and
routes, and starts the daemon. A virtual machine started in the
network namespace, wrapped by qrap, will now directly interface
with passt and communicate using Layer 4 sockets provided by the
host kernel.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2021-02-16 06:25:09 +00:00
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void tcp_sock_handler(struct ctx *c, int s, uint32_t events);
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2021-04-22 11:39:36 +00:00
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int tcp_tap_handler(struct ctx *c, int af, void *addr,
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struct tap_msg *msg, int count);
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passt: New design and implementation with native Layer 4 sockets
This is a reimplementation, partially building on the earlier draft,
that uses L4 sockets (SOCK_DGRAM, SOCK_STREAM) instead of SOCK_RAW,
providing L4-L2 translation functionality without requiring any
security capability.
Conceptually, this follows the design presented at:
https://gitlab.com/abologna/kubevirt-and-kvm/-/blob/master/Networking.md
The most significant novelty here comes from TCP and UDP translation
layers. In particular, the TCP state and translation logic follows
the intent of being minimalistic, without reimplementing a full TCP
stack in either direction, and synchronising as much as possible the
TCP dynamic and flows between guest and host kernel.
Another important introduction concerns addressing, port translation
and forwarding. The Layer 4 implementations now attempt to bind on
all unbound ports, in order to forward connections in a transparent
way.
While at it:
- the qemu 'tap' back-end can't be used as-is by qrap anymore,
because of explicit checks now introduced in qemu to ensure that
the corresponding file descriptor is actually a tap device. For
this reason, qrap now operates on a 'socket' back-end type,
accounting for and building the additional header reporting
frame length
- provide a demo script that sets up namespaces, addresses and
routes, and starts the daemon. A virtual machine started in the
network namespace, wrapped by qrap, will now directly interface
with passt and communicate using Layer 4 sockets provided by the
host kernel.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2021-02-16 06:25:09 +00:00
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int tcp_sock_init(struct ctx *c);
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passt: Assorted fixes from "fresh eyes" review
A bunch of fixes not worth single commits at this stage, notably:
- make buffer, length parameter ordering consistent in ARP, DHCP,
NDP handlers
- strict checking of buffer, message and option length in DHCP
handler (a malicious client could have easily crashed it)
- set up forwarding for IPv4 and IPv6, and masquerading with nft for
IPv4, from demo script
- get rid of separate slow and fast timers, we don't save any
overhead that way
- stricter checking of buffer lengths as passed to tap handlers
- proper dequeuing from qemu socket back-end: I accidentally trashed
messages that were bundled up together in a single tap read
operation -- the length header tells us what's the size of the next
frame, but there's no apparent limit to the number of messages we
get with one single receive
- rework some bits of the TCP state machine, now passive and active
connection closes appear to be robust -- introduce a new
FIN_WAIT_1_SOCK_FIN state indicating a FIN_WAIT_1 with a FIN flag
from socket
- streamline TCP option parsing routine
- track TCP state changes to stderr (this is temporary, proper
debugging and syslogging support pending)
- observe that multiplying a number by four might very well change
its value, and this happens to be the case for the data offset
from the TCP header as we check if it's the same as the total
length to find out if it's a duplicated ACK segment
- recent estimates suggest that the duration of a millisecond is
closer to a million nanoseconds than a thousand of them, this
trend is now reflected into the timespec_diff_ms() convenience
routine
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2021-02-21 10:33:38 +00:00
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void tcp_timer(struct ctx *c, struct timespec *ts);
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2021-03-17 09:57:41 +00:00
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/**
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* struct tcp_ctx - Execution context for TCP routines
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* @hash_secret: 128-bit secret for hash functions, ISN and hash table
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passt: Spare some syscalls, add some optimisations from profiling
Avoid a bunch of syscalls on forwarding paths by:
- storing minimum and maximum file descriptor numbers for each
protocol, fall back to SO_PROTOCOL query only on overlaps
- allocating a larger receive buffer -- this can result in more
coalesced packets than sendmmsg() can take (UIO_MAXIOV, i.e. 1024),
so make sure we don't exceed that within a single call to protocol
tap handlers
- nesting the handling loop in tap_handler() in the receive loop,
so that we have better chances of filling our receive buffer in
fewer calls
- skipping the recvfrom() in the UDP handler on EPOLLERR -- there's
nothing to be done in that case
and while at it:
- restore the 20ms timer interval for periodic (TCP) events, I
accidentally changed that to 100ms in an earlier commit
- attempt using SO_ZEROCOPY for UDP -- if it's not available,
sendmmsg() will succeed anyway
- fix the handling of the status code from sendmmsg(), if it fails,
we'll try to discard the first message, hence return 1 from the
UDP handler
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2021-04-23 20:22:37 +00:00
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* @fd_min: Lowest file descriptor number for TCP ever used
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* @fd_max: Highest file descriptor number for TCP ever used
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2021-04-25 11:34:04 +00:00
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* @fd_listen_min: Lowest file descriptor number for listening sockets
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* @fd_listen_max: Highest file descriptor number for listening sockets
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* @fd_conn_min: Lowest file descriptor number for connected sockets
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* @fd_conn_max: Highest file descriptor number for connected sockets
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2021-03-17 09:57:41 +00:00
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*/
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struct tcp_ctx {
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uint64_t hash_secret[2];
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passt: Spare some syscalls, add some optimisations from profiling
Avoid a bunch of syscalls on forwarding paths by:
- storing minimum and maximum file descriptor numbers for each
protocol, fall back to SO_PROTOCOL query only on overlaps
- allocating a larger receive buffer -- this can result in more
coalesced packets than sendmmsg() can take (UIO_MAXIOV, i.e. 1024),
so make sure we don't exceed that within a single call to protocol
tap handlers
- nesting the handling loop in tap_handler() in the receive loop,
so that we have better chances of filling our receive buffer in
fewer calls
- skipping the recvfrom() in the UDP handler on EPOLLERR -- there's
nothing to be done in that case
and while at it:
- restore the 20ms timer interval for periodic (TCP) events, I
accidentally changed that to 100ms in an earlier commit
- attempt using SO_ZEROCOPY for UDP -- if it's not available,
sendmmsg() will succeed anyway
- fix the handling of the status code from sendmmsg(), if it fails,
we'll try to discard the first message, hence return 1 from the
UDP handler
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2021-04-23 20:22:37 +00:00
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int fd_min;
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int fd_max;
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2021-04-25 11:34:04 +00:00
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int fd_listen_min;
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int fd_listen_max;
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int fd_conn_min;
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int fd_conn_max;
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2021-03-17 09:57:41 +00:00
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};
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#endif /* TCP_H */
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