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passt/tcp.c
Stefano Brivio feaeb4986c tcp: Fix comment to tcp_sock_consume() 
Note that tcp_sock_consume() doesn't update ACK sequence counters
anymore.

Fixes: cc6d8286d1 ("tcp: Reset ACK_FROM_TAP_DUE flag only as needed, update timer")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
2023-10-04 23:24:08 +02:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* PASST - Plug A Simple Socket Transport
* for qemu/UNIX domain socket mode
*
* PASTA - Pack A Subtle Tap Abstraction
* for network namespace/tap device mode
*
* tcp.c - TCP L2-L4 translation state machine
*
* Copyright (c) 2020-2022 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
/**
* DOC: Theory of Operation
*
*
* PASST mode
* ==========
*
* This implementation maps TCP traffic between a single L2 interface (tap) and
* native TCP (L4) sockets, mimicking and reproducing as closely as possible the
* inferred behaviour of applications running on a guest, connected via said L2
* interface. Four connection flows are supported:
* - from the local host to the guest behind the tap interface:
* - this is the main use case for proxies in service meshes
* - we bind to configured local ports, and relay traffic between L4 sockets
* with local endpoints and the L2 interface
* - from remote hosts to the guest behind the tap interface:
* - this might be needed for services that need to be addressed directly,
* and typically configured with special port forwarding rules (which are
* not needed here)
* - we also relay traffic between L4 sockets with remote endpoints and the L2
* interface
* - from the guest to the local host:
* - this is not observed in practice, but implemented for completeness and
* transparency
* - from the guest to external hosts:
* - this might be needed for applications running on the guest that need to
* directly access internet services (e.g. NTP)
*
* Relevant goals are:
* - transparency: sockets need to behave as if guest applications were running
* directly on the host. This is achieved by:
* - avoiding port and address translations whenever possible
* - mirroring TCP dynamics by observation of socket parameters (TCP_INFO
* socket option) and TCP headers of packets coming from the tap interface,
* reapplying those parameters in both flow directions (including TCP_MSS,
* TCP_WINDOW_CLAMP socket options)
* - simplicity: only a small subset of TCP logic is implemented here and
* delegated as much as possible to the TCP implementations of guest and host
* kernel. This is achieved by:
* - avoiding a complete TCP stack reimplementation, with a modified TCP state
* machine focused on the translation of observed events instead
* - mirroring TCP dynamics as described above and hence avoiding the need for
* segmentation, explicit queueing, and reassembly of segments
* - security:
* - no dynamic memory allocation is performed
* - TODO: synflood protection
*
* Portability is limited by usage of Linux-specific socket options.
*
*
* Limits
* ------
*
* To avoid the need for dynamic memory allocation, a maximum, reasonable amount
* of connections is defined by TCP_MAX_CONNS (currently 128k).
*
* Data needs to linger on sockets as long as it's not acknowledged by the
* guest, and is read using MSG_PEEK into preallocated static buffers sized
* to the maximum supported window, 16 MiB ("discard" buffer, for already-sent
* data) plus a number of maximum-MSS-sized buffers. This imposes a practical
* limitation on window scaling, that is, the maximum factor is 256. Larger
* factors will be accepted, but resulting, larger values are never advertised
* to the other side, and not used while queueing data.
*
*
* Ports
* -----
*
* To avoid the need for ad-hoc configuration of port forwarding or allowed
* ports, listening sockets can be opened and bound to all unbound ports on the
* host, as far as process capabilities allow. This service needs to be started
* after any application proxy that needs to bind to local ports. Mapped ports
* can also be configured explicitly.
*
* No port translation is needed for connections initiated remotely or by the
* local host: source port from socket is reused while establishing connections
* to the guest.
*
* For connections initiated by the guest, it's not possible to force the same
* source port as connections are established by the host kernel: that's the
* only port translation needed.
*
*
* Connection tracking and storage
* -------------------------------
*
* Connections are tracked by struct tcp_tap_conn entries in the @tc
* array, containing addresses, ports, TCP states and parameters. This
* is statically allocated and indexed by an arbitrary connection
* number. The array is compacted whenever a connection is closed, by
* remapping the highest connection index in use to the one freed up.
*
* References used for the epoll interface report the connection index used for
* the @tc array.
*
* IPv4 addresses are stored as IPv4-mapped IPv6 addresses to avoid the need for
* separate data structures depending on the protocol version.
*
* - Inbound connection requests (to the guest) are mapped using the triple
* < source IP address, source port, destination port >
* - Outbound connection requests (from the guest) are mapped using the triple
* < destination IP address, destination port, source port >
* where the source port is the one used by the guest, not the one used by the
* corresponding host socket
*
*
* Initialisation
* --------------
*
* Up to 2^15 + 2^14 listening sockets (excluding ephemeral ports, repeated for
* IPv4 and IPv6) can be opened and bound to wildcard addresses. Some will fail
* to bind (for low ports, or ports already bound, e.g. by a proxy). These are
* added to the epoll list, with no separate storage.
*
*
* Events and states
* -----------------
*
* Instead of tracking connection states using a state machine, connection
* events are used to determine state and actions for a given connection. This
* makes the implementation simpler as most of the relevant tasks deal with
* reactions to events, rather than state-associated actions. For user
* convenience, approximate states are mapped in logs from events by
* @tcp_state_str.
*
* The events are:
*
* - SOCK_ACCEPTED connection accepted from socket, SYN sent to tap/guest
*
* - TAP_SYN_RCVD tap/guest initiated connection, SYN received
*
* - TAP_SYN_ACK_SENT SYN, ACK sent to tap/guest, valid for TAP_SYN_RCVD only
*
* - ESTABLISHED connection established, the following events are valid:
*
* - SOCK_FIN_RCVD FIN (EPOLLRDHUP) received from socket
*
* - SOCK_FIN_SENT FIN (write shutdown) sent to socket
*
* - TAP_FIN_RCVD FIN received from tap/guest
*
* - TAP_FIN_SENT FIN sent to tap/guest
*
* - TAP_FIN_ACKED ACK to FIN seen from tap/guest
*
* Setting any event in CONN_STATE_BITS (SOCK_ACCEPTED, TAP_SYN_RCVD,
* ESTABLISHED) clears all the other events, as those represent the fundamental
* connection states. No events (events == CLOSED) means the connection is
* closed.
*
* Connection setup
* ----------------
*
* - inbound connection (from socket to guest): on accept() from listening
* socket, the new socket is mapped in connection tracking table, and
* three-way handshake initiated towards the guest, advertising MSS and window
* size and scaling from socket parameters
* - outbound connection (from guest to socket): on SYN segment from guest, a
* new socket is created and mapped in connection tracking table, setting
* MSS and window clamping from header and option of the observed SYN segment
*
*
* Aging and timeout
* -----------------
*
* Timeouts are implemented by means of timerfd timers, set based on flags:
*
* - SYN_TIMEOUT: if no ACK is received from tap/guest during handshake (flag
* ACK_FROM_TAP_DUE without ESTABLISHED event) within this time, reset the
* connection
*
* - ACK_TIMEOUT: if no ACK segment was received from tap/guest, after sending
* data (flag ACK_FROM_TAP_DUE with ESTABLISHED event), re-send data from the
* socket and reset sequence to what was acknowledged. If this persists for
* more than TCP_MAX_RETRANS times in a row, reset the connection
*
* - FIN_TIMEOUT: if a FIN segment was sent to tap/guest (flag ACK_FROM_TAP_DUE
* with TAP_FIN_SENT event), and no ACK is received within this time, reset
* the connection
*
* - FIN_TIMEOUT: if a FIN segment was acknowledged by tap/guest and a FIN
* segment (write shutdown) was sent via socket (events SOCK_FIN_SENT and
* TAP_FIN_ACKED), but no socket activity is detected from the socket within
* this time, reset the connection
*
* - ACT_TIMEOUT, in the presence of any event: if no activity is detected on
* either side, the connection is reset
*
* - ACK_INTERVAL elapsed after data segment received from tap without having
* sent an ACK segment, or zero-sized window advertised to tap/guest (flag
* ACK_TO_TAP_DUE): forcibly check if an ACK segment can be sent
*
*
* Summary of data flows (with ESTABLISHED event)
* ----------------------------------------------
*
* @seq_to_tap: next sequence for packets to tap/guest
* @seq_ack_from_tap: last ACK number received from tap/guest
* @seq_from_tap: next sequence for packets from tap/guest (expected)
* @seq_ack_to_tap: last ACK number sent to tap/guest
*
* @seq_init_from_tap: initial sequence number from tap/guest
* @seq_init_to_tap: initial sequence number from tap/guest
*
* @wnd_from_tap: last window size received from tap, never scaled
* @wnd_from_tap: last window size advertised from tap, never scaled
*
* - from socket to tap/guest:
* - on new data from socket:
* - peek into buffer
* - send data to tap/guest:
* - starting at offset (@seq_to_tap - @seq_ack_from_tap)
* - in MSS-sized segments
* - increasing @seq_to_tap at each segment
* - up to window (until @seq_to_tap - @seq_ack_from_tap <= @wnd_from_tap)
* - on read error, send RST to tap/guest, close socket
* - on zero read, send FIN to tap/guest, set TAP_FIN_SENT
* - on ACK from tap/guest:
* - set @ts_ack_from_tap
* - check if it's the second duplicated ACK
* - consume buffer by difference between new ack_seq and @seq_ack_from_tap
* - update @seq_ack_from_tap from ack_seq in header
* - on two duplicated ACKs, reset @seq_to_tap to @seq_ack_from_tap, and
* resend with steps listed above
* - set TCP_WINDOW_CLAMP from TCP header from tap
*
* - from tap/guest to socket:
* - on packet from tap/guest:
* - set @ts_tap_act
* - set TCP_WINDOW_CLAMP from TCP header from tap
* - check seq from header against @seq_from_tap, if data is missing, send
* two ACKs with number @seq_ack_to_tap, discard packet
* - otherwise queue data to socket, set @seq_from_tap to seq from header
* plus payload length
* - in ESTABLISHED state, send ACK to tap as soon as we queue to the
* socket. In other states, query socket for TCP_INFO, set
* @seq_ack_to_tap to (tcpi_bytes_acked + @seq_init_from_tap) % 2^32 and
* send ACK to tap/guest
*
*
* PASTA mode
* ==========
*
* For traffic directed to TCP ports configured for mapping to the tuntap device
* in the namespace, and for non-local traffic coming from the tuntap device,
* the implementation is identical as the PASST mode described in the previous
* section.
*
* For local traffic directed to TCP ports configured for direct mapping between
* namespaces, see the implementation in tcp_splice.c.
*/
#include <sched.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <errno.h>
#include <limits.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
#include <string.h>
#include <sys/epoll.h>
#ifdef HAS_GETRANDOM
#include <sys/random.h>
#endif
#include <sys/socket.h>
#include <sys/timerfd.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <time.h>
#include <linux/tcp.h> /* For struct tcp_info */
#include "checksum.h"
#include "util.h"
#include "passt.h"
#include "tap.h"
#include "siphash.h"
#include "pcap.h"
#include "conf.h"
#include "tcp_splice.h"
#include "log.h"
#include "inany.h"
#include "tcp_conn.h"
#define TCP_FRAMES_MEM 128
#define TCP_FRAMES \
(c->mode == MODE_PASST ? TCP_FRAMES_MEM : 1)
#define TCP_HASH_TABLE_LOAD 70 /* % */
#define TCP_HASH_TABLE_SIZE (TCP_MAX_CONNS * 100 / \
TCP_HASH_TABLE_LOAD)
#define MAX_WS 8
#define MAX_WINDOW (1 << (16 + (MAX_WS)))
/* MSS rounding: see SET_MSS() */
#define MSS_DEFAULT 536
struct tcp4_l2_head { /* For MSS4 macro: keep in sync with tcp4_l2_buf_t */
#ifdef __AVX2__
uint8_t pad[26];
#else
uint8_t pad[2];
#endif
struct tap_hdr taph;
struct iphdr iph;
struct tcphdr th;
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)));
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))));
#endif
struct tcp6_l2_head { /* For MSS6 macro: keep in sync with tcp6_l2_buf_t */
#ifdef __AVX2__
uint8_t pad[14];
#else
uint8_t pad[2];
#endif
struct tap_hdr taph;
struct ipv6hdr ip6h;
struct tcphdr th;
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)));
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))));
#endif
#define MSS4 ROUND_DOWN(USHRT_MAX - sizeof(struct tcp4_l2_head), 4)
#define MSS6 ROUND_DOWN(USHRT_MAX - sizeof(struct tcp6_l2_head), 4)
#define WINDOW_DEFAULT 14600 /* RFC 6928 */
#ifdef HAS_SND_WND
# define KERNEL_REPORTS_SND_WND(c) (c->tcp.kernel_snd_wnd)
#else
# define KERNEL_REPORTS_SND_WND(c) (0 && (c))
#endif
#define ACK_INTERVAL 10 /* ms */
#define SYN_TIMEOUT 10 /* s */
#define ACK_TIMEOUT 2
#define FIN_TIMEOUT 60
#define ACT_TIMEOUT 7200
#define LOW_RTT_TABLE_SIZE 8
#define LOW_RTT_THRESHOLD 10 /* us */
/* We need to include <linux/tcp.h> for tcpi_bytes_acked, instead of
* <netinet/tcp.h>, but that doesn't include a definition for SOL_TCP
*/
#define SOL_TCP IPPROTO_TCP
#define SEQ_LE(a, b) ((b) - (a) < MAX_WINDOW)
#define SEQ_LT(a, b) ((b) - (a) - 1 < MAX_WINDOW)
#define SEQ_GE(a, b) ((a) - (b) < MAX_WINDOW)
#define SEQ_GT(a, b) ((a) - (b) - 1 < MAX_WINDOW)
#define FIN (1 << 0)
#define SYN (1 << 1)
#define RST (1 << 2)
#define ACK (1 << 4)
/* Flags for internal usage */
#define DUP_ACK (1 << 5)
#define ACK_IF_NEEDED 0 /* See tcp_send_flag() */
#define OPT_EOL 0
#define OPT_NOP 1
#define OPT_MSS 2
#define OPT_MSS_LEN 4
#define OPT_WS 3
#define OPT_WS_LEN 3
#define OPT_SACKP 4
#define OPT_SACK 5
#define OPT_TS 8
#define CONN_V4(conn) (!!inany_v4(&(conn)->faddr))
#define CONN_V6(conn) (!CONN_V4(conn))
#define CONN_IS_CLOSING(conn) \
((conn->events & ESTABLISHED) && \
(conn->events & (SOCK_FIN_RCVD | TAP_FIN_RCVD)))
#define CONN_HAS(conn, set) ((conn->events & (set)) == (set))
static const char *tcp_event_str[] __attribute((__unused__)) = {
"SOCK_ACCEPTED", "TAP_SYN_RCVD", "ESTABLISHED", "TAP_SYN_ACK_SENT",
"SOCK_FIN_RCVD", "SOCK_FIN_SENT", "TAP_FIN_RCVD", "TAP_FIN_SENT",
"TAP_FIN_ACKED",
};
static const char *tcp_state_str[] __attribute((__unused__)) = {
"SYN_RCVD", "SYN_SENT", "ESTABLISHED",
"SYN_RCVD", /* approximately maps to TAP_SYN_ACK_SENT */
/* Passive close: */
"CLOSE_WAIT", "CLOSE_WAIT", "LAST_ACK", "LAST_ACK", "LAST_ACK",
/* Active close (+5): */
"CLOSING", "FIN_WAIT_1", "FIN_WAIT_1", "FIN_WAIT_2", "TIME_WAIT",
};
static const char *tcp_flag_str[] __attribute((__unused__)) = {
"STALLED", "LOCAL", "WND_CLAMPED", "ACTIVE_CLOSE", "ACK_TO_TAP_DUE",
"ACK_FROM_TAP_DUE",
};
/* Listening sockets, used for automatic port forwarding in pasta mode only */
static int tcp_sock_init_ext [NUM_PORTS][IP_VERSIONS];
static int tcp_sock_ns [NUM_PORTS][IP_VERSIONS];
/* Table of guest side forwarding addresses with very low RTT (assumed
* to be local to the host), LRU
*/
static union inany_addr low_rtt_dst[LOW_RTT_TABLE_SIZE];
/* Static buffers */
/**
* tcp4_l2_buf_t - Pre-cooked IPv4 packet buffers for tap connections
* @pad: Align TCP header to 32 bytes, for AVX2 checksum calculation only
* @taph: Tap-level headers (partially pre-filled)
* @iph: Pre-filled IP header (except for tot_len and saddr)
* @uh: Headroom for TCP header
* @data: Storage for TCP payload
*/
static struct tcp4_l2_buf_t {
#ifdef __AVX2__
uint8_t pad[26]; /* 0, align th to 32 bytes */
#else
uint8_t pad[2]; /* align iph to 4 bytes 0 */
#endif
struct tap_hdr taph; /* 26 2 */
struct iphdr iph; /* 44 20 */
struct tcphdr th; /* 64 40 */
uint8_t data[MSS4]; /* 84 60 */
/* 65536 65532 */
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)))
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))))
#endif
tcp4_l2_buf[TCP_FRAMES_MEM];
static unsigned int tcp4_l2_buf_used;
/**
* tcp6_l2_buf_t - Pre-cooked IPv6 packet buffers for tap connections
* @pad: Align IPv6 header for checksum calculation to 32B (AVX2) or 4B
* @taph: Tap-level headers (partially pre-filled)
* @ip6h: Pre-filled IP header (except for payload_len and addresses)
* @th: Headroom for TCP header
* @data: Storage for TCP payload
*/
struct tcp6_l2_buf_t {
#ifdef __AVX2__
uint8_t pad[14]; /* 0 align ip6h to 32 bytes */
#else
uint8_t pad[2]; /* align ip6h to 4 bytes 0 */
#endif
struct tap_hdr taph; /* 14 2 */
struct ipv6hdr ip6h; /* 32 20 */
struct tcphdr th; /* 72 60 */
uint8_t data[MSS6]; /* 92 80 */
/* 65536 65532 */
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)))
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))))
#endif
tcp6_l2_buf[TCP_FRAMES_MEM];
static unsigned int tcp6_l2_buf_used;
/* recvmsg()/sendmsg() data for tap */
static char tcp_buf_discard [MAX_WINDOW];
static struct iovec iov_sock [TCP_FRAMES_MEM + 1];
static struct iovec tcp4_l2_iov [TCP_FRAMES_MEM];
static struct iovec tcp6_l2_iov [TCP_FRAMES_MEM];
static struct iovec tcp4_l2_flags_iov [TCP_FRAMES_MEM];
static struct iovec tcp6_l2_flags_iov [TCP_FRAMES_MEM];
static struct mmsghdr tcp_l2_mh [TCP_FRAMES_MEM];
/* sendmsg() to socket */
static struct iovec tcp_iov [UIO_MAXIOV];
/**
* tcp4_l2_flags_buf_t - IPv4 packet buffers for segments without data (flags)
* @pad: Align TCP header to 32 bytes, for AVX2 checksum calculation only
* @taph: Tap-level headers (partially pre-filled)
* @iph: Pre-filled IP header (except for tot_len and saddr)
* @th: Headroom for TCP header
* @opts: Headroom for TCP options
*/
static struct tcp4_l2_flags_buf_t {
#ifdef __AVX2__
uint8_t pad[26]; /* 0, align th to 32 bytes */
#else
uint8_t pad[2]; /* align iph to 4 bytes 0 */
#endif
struct tap_hdr taph; /* 26 2 */
struct iphdr iph; /* 44 20 */
struct tcphdr th; /* 64 40 */
char opts[OPT_MSS_LEN + OPT_WS_LEN + 1];
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)))
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))))
#endif
tcp4_l2_flags_buf[TCP_FRAMES_MEM];
static unsigned int tcp4_l2_flags_buf_used;
/**
* tcp6_l2_flags_buf_t - IPv6 packet buffers for segments without data (flags)
* @pad: Align IPv6 header for checksum calculation to 32B (AVX2) or 4B
* @taph: Tap-level headers (partially pre-filled)
* @ip6h: Pre-filled IP header (except for payload_len and addresses)
* @th: Headroom for TCP header
* @opts: Headroom for TCP options
*/
static struct tcp6_l2_flags_buf_t {
#ifdef __AVX2__
uint8_t pad[14]; /* 0 align ip6h to 32 bytes */
#else
uint8_t pad[2]; /* align ip6h to 4 bytes 0 */
#endif
struct tap_hdr taph; /* 14 2 */
struct ipv6hdr ip6h; /* 32 20 */
struct tcphdr th /* 72 */ __attribute__ ((aligned(4))); /* 60 */
char opts[OPT_MSS_LEN + OPT_WS_LEN + 1];
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)))
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))))
#endif
tcp6_l2_flags_buf[TCP_FRAMES_MEM];
static unsigned int tcp6_l2_flags_buf_used;
/* TCP connections */
union tcp_conn tc[TCP_MAX_CONNS];
#define CONN(idx) (&tc[(idx)].tap)
#define CONN_IDX(conn) ((union tcp_conn *)(conn) - tc)
/** conn_at_idx() - Find a connection by index, if present
* @idx: Index of connection to lookup
*
* Return: pointer to connection, or NULL if @idx is out of bounds
*/
static inline struct tcp_tap_conn *conn_at_idx(int idx)
{
if ((idx < 0) || (idx >= TCP_MAX_CONNS))
return NULL;
ASSERT(!(CONN(idx)->c.spliced));
return CONN(idx);
}
/* Table for lookup from remote address, local port, remote port */
static struct tcp_tap_conn *tc_hash[TCP_HASH_TABLE_SIZE];
/* Pools for pre-opened sockets (in init) */
int init_sock_pool4 [TCP_SOCK_POOL_SIZE];
int init_sock_pool6 [TCP_SOCK_POOL_SIZE];
/**
* tcp_conn_epoll_events() - epoll events mask for given connection state
* @events: Current connection events
* @conn_flags Connection flags
*
* Return: epoll events mask corresponding to implied connection state
*/
static uint32_t tcp_conn_epoll_events(uint8_t events, uint8_t conn_flags)
{
if (!events)
return 0;
if (events & ESTABLISHED) {
if (events & TAP_FIN_SENT)
return EPOLLET;
if (conn_flags & STALLED)
return EPOLLIN | EPOLLOUT | EPOLLRDHUP | EPOLLET;
return EPOLLIN | EPOLLRDHUP;
}
if (events == TAP_SYN_RCVD)
return EPOLLOUT | EPOLLET | EPOLLRDHUP;
return EPOLLRDHUP;
}
static void conn_flag_do(const struct ctx *c, struct tcp_tap_conn *conn,
unsigned long flag);
#define conn_flag(c, conn, flag) \
do { \
trace("TCP: flag at %s:%i", __func__, __LINE__); \
conn_flag_do(c, conn, flag); \
} while (0)
/**
* tcp_epoll_ctl() - Add/modify/delete epoll state from connection events
* @c: Execution context
* @conn: Connection pointer
*
* Return: 0 on success, negative error code on failure (not on deletion)
*/
static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
{
int m = conn->in_epoll ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
union epoll_ref ref = { .type = EPOLL_TYPE_TCP, .fd = conn->sock,
.tcp.index = CONN_IDX(conn) };
struct epoll_event ev = { .data.u64 = ref.u64 };
if (conn->events == CLOSED) {
if (conn->in_epoll)
epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->sock, &ev);
if (conn->timer != -1)
epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->timer, &ev);
return 0;
}
ev.events = tcp_conn_epoll_events(conn->events, conn->flags);
if (epoll_ctl(c->epollfd, m, conn->sock, &ev))
return -errno;
conn->in_epoll = true;
if (conn->timer != -1) {
union epoll_ref ref_t = { .type = EPOLL_TYPE_TCP_TIMER,
.fd = conn->sock,
.tcp.index = CONN_IDX(conn) };
struct epoll_event ev_t = { .data.u64 = ref_t.u64,
.events = EPOLLIN | EPOLLET };
if (epoll_ctl(c->epollfd, EPOLL_CTL_MOD, conn->timer, &ev_t))
return -errno;
}
return 0;
}
/**
* tcp_timer_ctl() - Set timerfd based on flags/events, create timerfd if needed
* @c: Execution context
* @conn: Connection pointer
*
* #syscalls timerfd_create timerfd_settime
*/
static void tcp_timer_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
{
struct itimerspec it = { { 0 }, { 0 } };
if (conn->events == CLOSED)
return;
if (conn->timer == -1) {
union epoll_ref ref = { .type = EPOLL_TYPE_TCP_TIMER,
.fd = conn->sock,
.tcp.index = CONN_IDX(conn) };
struct epoll_event ev = { .data.u64 = ref.u64,
.events = EPOLLIN | EPOLLET };
int fd;
fd = timerfd_create(CLOCK_MONOTONIC, 0);
if (fd == -1 || fd > FD_REF_MAX) {
debug("TCP: failed to get timer: %s", strerror(errno));
if (fd > -1)
close(fd);
conn->timer = -1;
return;
}
conn->timer = fd;
if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, conn->timer, &ev)) {
debug("TCP: failed to add timer: %s", strerror(errno));
close(conn->timer);
conn->timer = -1;
return;
}
}
if (conn->flags & ACK_TO_TAP_DUE) {
it.it_value.tv_nsec = (long)ACK_INTERVAL * 1000 * 1000;
} else if (conn->flags & ACK_FROM_TAP_DUE) {
if (!(conn->events & ESTABLISHED))
it.it_value.tv_sec = SYN_TIMEOUT;
else
it.it_value.tv_sec = ACK_TIMEOUT;
} else if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED)) {
it.it_value.tv_sec = FIN_TIMEOUT;
} else {
it.it_value.tv_sec = ACT_TIMEOUT;
}
debug("TCP: index %li, timer expires in %lu.%03lus", CONN_IDX(conn),
it.it_value.tv_sec, it.it_value.tv_nsec / 1000 / 1000);
timerfd_settime(conn->timer, 0, &it, NULL);
}
/**
* conn_flag_do() - Set/unset given flag, log, update epoll on STALLED flag
* @c: Execution context
* @conn: Connection pointer
* @flag: Flag to set, or ~flag to unset
*/
static void conn_flag_do(const struct ctx *c, struct tcp_tap_conn *conn,
unsigned long flag)
{
if (flag & (flag - 1)) {
int flag_index = fls(~flag);
if (!(conn->flags & ~flag))
return;
conn->flags &= flag;
if (flag_index >= 0) {
debug("TCP: index %li: %s dropped", CONN_IDX(conn),
tcp_flag_str[flag_index]);
}
} else {
int flag_index = fls(flag);
if (conn->flags & flag) {
/* Special case: setting ACK_FROM_TAP_DUE on a
* connection where it's already set is used to
* re-schedule the existing timer.
* TODO: define clearer semantics for timer-related
* flags and factor this into the logic below.
*/
if (flag == ACK_FROM_TAP_DUE)
tcp_timer_ctl(c, conn);
return;
}
conn->flags |= flag;
if (flag_index >= 0) {
debug("TCP: index %li: %s", CONN_IDX(conn),
tcp_flag_str[flag_index]);
}
}
if (flag == STALLED || flag == ~STALLED)
tcp_epoll_ctl(c, conn);
if (flag == ACK_FROM_TAP_DUE || flag == ACK_TO_TAP_DUE ||
(flag == ~ACK_FROM_TAP_DUE && (conn->flags & ACK_TO_TAP_DUE)) ||
(flag == ~ACK_TO_TAP_DUE && (conn->flags & ACK_FROM_TAP_DUE)))
tcp_timer_ctl(c, conn);
}
/**
* conn_event_do() - Set and log connection events, update epoll state
* @c: Execution context
* @conn: Connection pointer
* @event: Connection event
*/
static void conn_event_do(const struct ctx *c, struct tcp_tap_conn *conn,
unsigned long event)
{
int prev, new, num = fls(event);
if (conn->events & event)
return;
prev = fls(conn->events);
if (conn->flags & ACTIVE_CLOSE)
prev += 5;
if ((conn->events & ESTABLISHED) && (conn->events != ESTABLISHED))
prev++; /* i.e. SOCK_FIN_RCVD, not TAP_SYN_ACK_SENT */
if (event == CLOSED || (event & CONN_STATE_BITS))
conn->events = event;
else
conn->events |= event;
new = fls(conn->events);
if ((conn->events & ESTABLISHED) && (conn->events != ESTABLISHED)) {
num++;
new++;
}
if (conn->flags & ACTIVE_CLOSE)
new += 5;
if (prev != new) {
debug("TCP: index %li, %s: %s -> %s", CONN_IDX(conn),
num == -1 ? "CLOSED" : tcp_event_str[num],
prev == -1 ? "CLOSED" : tcp_state_str[prev],
(new == -1 || num == -1) ? "CLOSED" : tcp_state_str[new]);
} else {
debug("TCP: index %li, %s", CONN_IDX(conn),
num == -1 ? "CLOSED" : tcp_event_str[num]);
}
if ((event == TAP_FIN_RCVD) && !(conn->events & SOCK_FIN_RCVD))
conn_flag(c, conn, ACTIVE_CLOSE);
else
tcp_epoll_ctl(c, conn);
if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED))
tcp_timer_ctl(c, conn);
}
#define conn_event(c, conn, event) \
do { \
trace("TCP: event at %s:%i", __func__, __LINE__); \
conn_event_do(c, conn, event); \
} while (0)
/**
* tcp_rtt_dst_low() - Check if low RTT was seen for connection endpoint
* @conn: Connection pointer
*
* Return: 1 if destination is in low RTT table, 0 otherwise
*/
static int tcp_rtt_dst_low(const struct tcp_tap_conn *conn)
{
int i;
for (i = 0; i < LOW_RTT_TABLE_SIZE; i++)
if (inany_equals(&conn->faddr, low_rtt_dst + i))
return 1;
return 0;
}
/**
* tcp_rtt_dst_check() - Check tcpi_min_rtt, insert endpoint in table if low
* @conn: Connection pointer
* @tinfo: Pointer to struct tcp_info for socket
*/
static void tcp_rtt_dst_check(const struct tcp_tap_conn *conn,
const struct tcp_info *tinfo)
{
#ifdef HAS_MIN_RTT
int i, hole = -1;
if (!tinfo->tcpi_min_rtt ||
(int)tinfo->tcpi_min_rtt > LOW_RTT_THRESHOLD)
return;
for (i = 0; i < LOW_RTT_TABLE_SIZE; i++) {
if (inany_equals(&conn->faddr, low_rtt_dst + i))
return;
if (hole == -1 && IN6_IS_ADDR_UNSPECIFIED(low_rtt_dst + i))
hole = i;
}
/* Keep gcc 12 happy: this won't actually happen because the table is
* guaranteed to have a hole, see the second memcpy() below.
*/
if (hole == -1)
return;
low_rtt_dst[hole++] = conn->faddr;
if (hole == LOW_RTT_TABLE_SIZE)
hole = 0;
inany_from_af(low_rtt_dst + hole, AF_INET6, &in6addr_any);
#else
(void)conn;
(void)tinfo;
#endif /* HAS_MIN_RTT */
}
/**
* tcp_get_sndbuf() - Get, scale SO_SNDBUF between thresholds (1 to 0.5 usage)
* @conn: Connection pointer
*/
static void tcp_get_sndbuf(struct tcp_tap_conn *conn)
{
int s = conn->sock, sndbuf;
socklen_t sl;
uint64_t v;
sl = sizeof(sndbuf);
if (getsockopt(s, SOL_SOCKET, SO_SNDBUF, &sndbuf, &sl)) {
SNDBUF_SET(conn, WINDOW_DEFAULT);
return;
}
v = sndbuf;
if (v >= SNDBUF_BIG)
v /= 2;
else if (v > SNDBUF_SMALL)
v -= v * (v - SNDBUF_SMALL) / (SNDBUF_BIG - SNDBUF_SMALL) / 2;
SNDBUF_SET(conn, MIN(INT_MAX, v));
}
/**
* tcp_sock_set_bufsize() - Set SO_RCVBUF and SO_SNDBUF to maximum values
* @s: Socket, can be -1 to avoid check in the caller
*/
void tcp_sock_set_bufsize(const struct ctx *c, int s)
{
int v = INT_MAX / 2; /* Kernel clamps and rounds, no need to check */
if (s == -1)
return;
if (!c->low_rmem && setsockopt(s, SOL_SOCKET, SO_RCVBUF, &v, sizeof(v)))
trace("TCP: failed to set SO_RCVBUF to %i", v);
if (!c->low_wmem && setsockopt(s, SOL_SOCKET, SO_SNDBUF, &v, sizeof(v)))
trace("TCP: failed to set SO_SNDBUF to %i", v);
}
/**
* tcp_update_check_ip4() - Update IPv4 with variable parts from stored one
* @buf: L2 packet buffer with final IPv4 header
*/
static void tcp_update_check_ip4(struct tcp4_l2_buf_t *buf)
{
uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_TCP);
sum += buf->iph.tot_len;
sum += (buf->iph.saddr >> 16) & 0xffff;
sum += buf->iph.saddr & 0xffff;
sum += (buf->iph.daddr >> 16) & 0xffff;
sum += buf->iph.daddr & 0xffff;
buf->iph.check = (uint16_t)~csum_fold(sum);
}
/**
* tcp_update_check_tcp4() - Update TCP checksum from stored one
* @buf: L2 packet buffer with final IPv4 header
*/
static void tcp_update_check_tcp4(struct tcp4_l2_buf_t *buf)
{
uint16_t tlen = ntohs(buf->iph.tot_len) - 20;
uint32_t sum = htons(IPPROTO_TCP);
sum += (buf->iph.saddr >> 16) & 0xffff;
sum += buf->iph.saddr & 0xffff;
sum += (buf->iph.daddr >> 16) & 0xffff;
sum += buf->iph.daddr & 0xffff;
sum += htons(ntohs(buf->iph.tot_len) - 20);
buf->th.check = 0;
buf->th.check = csum(&buf->th, tlen, sum);
}
/**
* tcp_update_check_tcp6() - Calculate TCP checksum for IPv6
* @buf: L2 packet buffer with final IPv6 header
*/
static void tcp_update_check_tcp6(struct tcp6_l2_buf_t *buf)
{
int len = ntohs(buf->ip6h.payload_len) + sizeof(struct ipv6hdr);
buf->ip6h.hop_limit = IPPROTO_TCP;
buf->ip6h.version = 0;
buf->ip6h.nexthdr = 0;
buf->th.check = 0;
buf->th.check = csum(&buf->ip6h, len, 0);
buf->ip6h.hop_limit = 255;
buf->ip6h.version = 6;
buf->ip6h.nexthdr = IPPROTO_TCP;
}
/**
* tcp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses
* @eth_d: Ethernet destination address, NULL if unchanged
* @eth_s: Ethernet source address, NULL if unchanged
*/
void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
{
int i;
for (i = 0; i < TCP_FRAMES_MEM; i++) {
struct tcp4_l2_flags_buf_t *b4f = &tcp4_l2_flags_buf[i];
struct tcp6_l2_flags_buf_t *b6f = &tcp6_l2_flags_buf[i];
struct tcp4_l2_buf_t *b4 = &tcp4_l2_buf[i];
struct tcp6_l2_buf_t *b6 = &tcp6_l2_buf[i];
tap_update_mac(&b4->taph, eth_d, eth_s);
tap_update_mac(&b6->taph, eth_d, eth_s);
tap_update_mac(&b4f->taph, eth_d, eth_s);
tap_update_mac(&b6f->taph, eth_d, eth_s);
}
}
/**
* tcp_sock4_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets
* @c: Execution context
*/
static void tcp_sock4_iov_init(const struct ctx *c)
{
struct iphdr iph = L2_BUF_IP4_INIT(IPPROTO_TCP);
struct iovec *iov;
int i;
for (i = 0; i < ARRAY_SIZE(tcp4_l2_buf); i++) {
tcp4_l2_buf[i] = (struct tcp4_l2_buf_t) {
.taph = TAP_HDR_INIT(ETH_P_IP),
.iph = iph,
.th = { .doff = sizeof(struct tcphdr) / 4, .ack = 1 }
};
}
for (i = 0; i < ARRAY_SIZE(tcp4_l2_flags_buf); i++) {
tcp4_l2_flags_buf[i] = (struct tcp4_l2_flags_buf_t) {
.taph = TAP_HDR_INIT(ETH_P_IP),
.iph = L2_BUF_IP4_INIT(IPPROTO_TCP)
};
}
for (i = 0, iov = tcp4_l2_iov; i < TCP_FRAMES_MEM; i++, iov++)
iov->iov_base = tap_iov_base(c, &tcp4_l2_buf[i].taph);
for (i = 0, iov = tcp4_l2_flags_iov; i < TCP_FRAMES_MEM; i++, iov++)
iov->iov_base = tap_iov_base(c, &tcp4_l2_flags_buf[i].taph);
}
/**
* tcp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets
* @c: Execution context
*/
static void tcp_sock6_iov_init(const struct ctx *c)
{
struct iovec *iov;
int i;
for (i = 0; i < ARRAY_SIZE(tcp6_l2_buf); i++) {
tcp6_l2_buf[i] = (struct tcp6_l2_buf_t) {
.taph = TAP_HDR_INIT(ETH_P_IPV6),
.ip6h = L2_BUF_IP6_INIT(IPPROTO_TCP),
.th = { .doff = sizeof(struct tcphdr) / 4, .ack = 1 }
};
}
for (i = 0; i < ARRAY_SIZE(tcp6_l2_flags_buf); i++) {
tcp6_l2_flags_buf[i] = (struct tcp6_l2_flags_buf_t) {
.taph = TAP_HDR_INIT(ETH_P_IPV6),
.ip6h = L2_BUF_IP6_INIT(IPPROTO_TCP)
};
}
for (i = 0, iov = tcp6_l2_iov; i < TCP_FRAMES_MEM; i++, iov++)
iov->iov_base = tap_iov_base(c, &tcp6_l2_buf[i].taph);
for (i = 0, iov = tcp6_l2_flags_iov; i < TCP_FRAMES_MEM; i++, iov++)
iov->iov_base = tap_iov_base(c, &tcp6_l2_flags_buf[i].taph);
}
/**
* tcp_opt_get() - Get option, and value if any, from TCP header
* @opts: Pointer to start of TCP options in header
* @len: Length of buffer, excluding TCP header -- NOT checked here!
* @type_find: Option type to look for
* @optlen_set: Optional, filled with option length if passed
* @value_set: Optional, set to start of option value if passed
*
* Return: option value, meaningful for up to 4 bytes, -1 if not found
*/
static int tcp_opt_get(const char *opts, size_t len, uint8_t type_find,
uint8_t *optlen_set, const char **value_set)
{
uint8_t type, optlen;
if (!opts || !len)
return -1;
for (; len >= 2; opts += optlen, len -= optlen) {
switch (*opts) {
case OPT_EOL:
return -1;
case OPT_NOP:
optlen = 1;
break;
default:
type = *(opts++);
if (*(uint8_t *)opts < 2 || *(uint8_t *)opts > len)
return -1;
optlen = *(opts++) - 2;
len -= 2;
if (type != type_find)
break;
if (optlen_set)
*optlen_set = optlen;
if (value_set)
*value_set = opts;
switch (optlen) {
case 0:
return 0;
case 1:
return *opts;
case 2:
return ntohs(*(uint16_t *)opts);
default:
return ntohl(*(uint32_t *)opts);
}
}
}
return -1;
}
/**
* tcp_hash_match() - Check if a connection entry matches address and ports
* @conn: Connection entry to match against
* @faddr: Guest side forwarding address
* @eport: Guest side endpoint port
* @fport: Guest side forwarding port
*
* Return: 1 on match, 0 otherwise
*/
static int tcp_hash_match(const struct tcp_tap_conn *conn,
const union inany_addr *faddr,
in_port_t eport, in_port_t fport)
{
if (conn->events != CLOSED && inany_equals(&conn->faddr, faddr) &&
conn->eport == eport && conn->fport == fport)
return 1;
return 0;
}
/**
* tcp_hash() - Calculate hash value for connection given address and ports
* @c: Execution context
* @faddr: Guest side forwarding address
* @eport: Guest side endpoint port
* @fport: Guest side forwarding port
*
* Return: hash value, already modulo size of the hash table
*/
static unsigned int tcp_hash(const struct ctx *c, const union inany_addr *faddr,
in_port_t eport, in_port_t fport)
{
struct siphash_state state = SIPHASH_INIT(c->tcp.hash_secret);
uint64_t hash;
inany_siphash_feed(&state, faddr);
hash = siphash_final(&state, 20, (uint64_t)eport << 16 | fport);
return (unsigned int)(hash % TCP_HASH_TABLE_SIZE);
}
/**
* tcp_conn_hash() - Calculate hash bucket of an existing connection
* @c: Execution context
* @conn: Connection
*
* Return: hash value, already modulo size of the hash table
*/
static unsigned int tcp_conn_hash(const struct ctx *c,
const struct tcp_tap_conn *conn)
{
return tcp_hash(c, &conn->faddr, conn->eport, conn->fport);
}
/**
* tcp_hash_insert() - Insert connection into hash table, chain link
* @c: Execution context
* @conn: Connection pointer
*/
static void tcp_hash_insert(const struct ctx *c, struct tcp_tap_conn *conn)
{
int b;
b = tcp_hash(c, &conn->faddr, conn->eport, conn->fport);
conn->next_index = tc_hash[b] ? CONN_IDX(tc_hash[b]) : -1;
tc_hash[b] = conn;
debug("TCP: hash table insert: index %li, sock %i, bucket: %i, next: "
"%p", CONN_IDX(conn), conn->sock, b, conn_at_idx(conn->next_index));
}
/**
* tcp_hash_remove() - Drop connection from hash table, chain unlink
* @c: Execution context
* @conn: Connection pointer
*/
static void tcp_hash_remove(const struct ctx *c,
const struct tcp_tap_conn *conn)
{
struct tcp_tap_conn *entry, *prev = NULL;
int b = tcp_conn_hash(c, conn);
for (entry = tc_hash[b]; entry;
prev = entry, entry = conn_at_idx(entry->next_index)) {
if (entry == conn) {
if (prev)
prev->next_index = conn->next_index;
else
tc_hash[b] = conn_at_idx(conn->next_index);
break;
}
}
debug("TCP: hash table remove: index %li, sock %i, bucket: %i, new: %p",
CONN_IDX(conn), conn->sock, b,
prev ? conn_at_idx(prev->next_index) : tc_hash[b]);
}
/**
* tcp_tap_conn_update() - Update tcp_tap_conn when being moved in the table
* @c: Execution context
* @old: Old location of tcp_tap_conn
* @new: New location of tcp_tap_conn
*/
static void tcp_tap_conn_update(const struct ctx *c, struct tcp_tap_conn *old,
struct tcp_tap_conn *new)
{
struct tcp_tap_conn *entry, *prev = NULL;
int b = tcp_conn_hash(c, old);
for (entry = tc_hash[b]; entry;
prev = entry, entry = conn_at_idx(entry->next_index)) {
if (entry == old) {
if (prev)
prev->next_index = CONN_IDX(new);
else
tc_hash[b] = new;
break;
}
}
debug("TCP: hash table update: old index %li, new index %li, sock %i, "
"bucket: %i, old: %p, new: %p",
CONN_IDX(old), CONN_IDX(new), new->sock, b, old, new);
tcp_epoll_ctl(c, new);
}
/**
* tcp_hash_lookup() - Look up connection given remote address and ports
* @c: Execution context
* @af: Address family, AF_INET or AF_INET6
* @faddr: Guest side forwarding address (guest remote address)
* @eport: Guest side endpoint port (guest local port)
* @fport: Guest side forwarding port (guest remote port)
*
* Return: connection pointer, if found, -ENOENT otherwise
*/
static struct tcp_tap_conn *tcp_hash_lookup(const struct ctx *c,
int af, const void *faddr,
in_port_t eport, in_port_t fport)
{
union inany_addr aany;
struct tcp_tap_conn *conn;
int b;
inany_from_af(&aany, af, faddr);
b = tcp_hash(c, &aany, eport, fport);
for (conn = tc_hash[b]; conn; conn = conn_at_idx(conn->next_index)) {
if (tcp_hash_match(conn, &aany, eport, fport))
return conn;
}
return NULL;
}
/**
* tcp_table_compact() - Perform compaction on connection table
* @c: Execution context
* @hole: Pointer to recently closed connection
*/
void tcp_table_compact(struct ctx *c, union tcp_conn *hole)
{
union tcp_conn *from;
if (CONN_IDX(hole) == --c->tcp.conn_count) {
debug("TCP: table compaction: maximum index was %li (%p)",
CONN_IDX(hole), hole);
memset(hole, 0, sizeof(*hole));
return;
}
from = tc + c->tcp.conn_count;
memcpy(hole, from, sizeof(*hole));
if (from->c.spliced)
tcp_splice_conn_update(c, &hole->splice);
else
tcp_tap_conn_update(c, &from->tap, &hole->tap);
debug("TCP: table compaction (spliced=%d): old index %li, new index %li, "
"from: %p, to: %p",
from->c.spliced, CONN_IDX(from), CONN_IDX(hole), from, hole);
memset(from, 0, sizeof(*from));
}
/**
* tcp_conn_destroy() - Close sockets, trigger hash table removal and compaction
* @c: Execution context
* @conn_union: Connection pointer (container union)
*/
static void tcp_conn_destroy(struct ctx *c, union tcp_conn *conn_union)
{
const struct tcp_tap_conn *conn = &conn_union->tap;
close(conn->sock);
if (conn->timer != -1)
close(conn->timer);
tcp_hash_remove(c, conn);
tcp_table_compact(c, conn_union);
}
static void tcp_rst_do(struct ctx *c, struct tcp_tap_conn *conn);
#define tcp_rst(c, conn) \
do { \
debug("TCP: index %li, reset at %s:%i", CONN_IDX(conn), \
__func__, __LINE__); \
tcp_rst_do(c, conn); \
} while (0)
/**
* tcp_l2_flags_buf_flush() - Send out buffers for segments with no data (flags)
* @c: Execution context
*/
static void tcp_l2_flags_buf_flush(const struct ctx *c)
{
tap_send_frames(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
tcp6_l2_flags_buf_used = 0;
tap_send_frames(c, tcp4_l2_flags_iov, tcp4_l2_flags_buf_used);
tcp4_l2_flags_buf_used = 0;
}
/**
* tcp_l2_data_buf_flush() - Send out buffers for segments with data
* @c: Execution context
*/
static void tcp_l2_data_buf_flush(const struct ctx *c)
{
tap_send_frames(c, tcp6_l2_iov, tcp6_l2_buf_used);
tcp6_l2_buf_used = 0;
tap_send_frames(c, tcp4_l2_iov, tcp4_l2_buf_used);
tcp4_l2_buf_used = 0;
}
/**
* tcp_defer_handler() - Handler for TCP deferred tasks
* @c: Execution context
*/
void tcp_defer_handler(struct ctx *c)
{
union tcp_conn *conn;
tcp_l2_flags_buf_flush(c);
tcp_l2_data_buf_flush(c);
for (conn = tc + c->tcp.conn_count - 1; conn >= tc; conn--) {
if (conn->c.spliced) {
if (conn->splice.flags & CLOSING)
tcp_splice_destroy(c, conn);
} else {
if (conn->tap.events == CLOSED)
tcp_conn_destroy(c, conn);
}
}
}
/**
* tcp_l2_buf_fill_headers() - Fill 802.3, IP, TCP headers in pre-cooked buffers
* @c: Execution context
* @conn: Connection pointer
* @p: Pointer to any type of TCP pre-cooked buffer
* @plen: Payload length (including TCP header options)
* @check: Checksum, if already known
* @seq: Sequence number for this segment
*
* Return: frame length including L2 headers, host order
*/
static size_t tcp_l2_buf_fill_headers(const struct ctx *c,
const struct tcp_tap_conn *conn,
void *p, size_t plen,
const uint16_t *check, uint32_t seq)
{
const struct in_addr *a4 = inany_v4(&conn->faddr);
size_t ip_len, tlen;
#define SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq) \
do { \
b->th.source = htons(conn->fport); \
b->th.dest = htons(conn->eport); \
b->th.seq = htonl(seq); \
b->th.ack_seq = htonl(conn->seq_ack_to_tap); \
if (conn->events & ESTABLISHED) { \
b->th.window = htons(conn->wnd_to_tap); \
} else { \
unsigned wnd = conn->wnd_to_tap << conn->ws_to_tap; \
\
b->th.window = htons(MIN(wnd, USHRT_MAX)); \
} \
} while (0)
if (a4) {
struct tcp4_l2_buf_t *b = (struct tcp4_l2_buf_t *)p;
ip_len = plen + sizeof(struct iphdr) + sizeof(struct tcphdr);
b->iph.tot_len = htons(ip_len);
b->iph.saddr = a4->s_addr;
b->iph.daddr = c->ip4.addr_seen.s_addr;
if (check)
b->iph.check = *check;
else
tcp_update_check_ip4(b);
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
tcp_update_check_tcp4(b);
tlen = tap_iov_len(c, &b->taph, ip_len);
} else {
struct tcp6_l2_buf_t *b = (struct tcp6_l2_buf_t *)p;
ip_len = plen + sizeof(struct ipv6hdr) + sizeof(struct tcphdr);
b->ip6h.payload_len = htons(plen + sizeof(struct tcphdr));
b->ip6h.saddr = conn->faddr.a6;
if (IN6_IS_ADDR_LINKLOCAL(&b->ip6h.saddr))
b->ip6h.daddr = c->ip6.addr_ll_seen;
else
b->ip6h.daddr = c->ip6.addr_seen;
memset(b->ip6h.flow_lbl, 0, 3);
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
tcp_update_check_tcp6(b);
b->ip6h.flow_lbl[0] = (conn->sock >> 16) & 0xf;
b->ip6h.flow_lbl[1] = (conn->sock >> 8) & 0xff;
b->ip6h.flow_lbl[2] = (conn->sock >> 0) & 0xff;
tlen = tap_iov_len(c, &b->taph, ip_len);
}
#undef SET_TCP_HEADER_COMMON_V4_V6
return tlen;
}
/**
* tcp_update_seqack_wnd() - Update ACK sequence and window to guest/tap
* @c: Execution context
* @conn: Connection pointer
* @force_seq: Force ACK sequence to latest segment, instead of checking socket
* @tinfo: tcp_info from kernel, can be NULL if not pre-fetched
*
* Return: 1 if sequence or window were updated, 0 otherwise
*/
static int tcp_update_seqack_wnd(const struct ctx *c, struct tcp_tap_conn *conn,
int force_seq, struct tcp_info *tinfo)
{
uint32_t prev_wnd_to_tap = conn->wnd_to_tap << conn->ws_to_tap;
uint32_t prev_ack_to_tap = conn->seq_ack_to_tap;
/* cppcheck-suppress [ctunullpointer, unmatchedSuppression] */
socklen_t sl = sizeof(*tinfo);
struct tcp_info tinfo_new;
uint32_t new_wnd_to_tap = prev_wnd_to_tap;
int s = conn->sock;
#ifndef HAS_BYTES_ACKED
(void)force_seq;
conn->seq_ack_to_tap = conn->seq_from_tap;
if (SEQ_LT(conn->seq_ack_to_tap, prev_ack_to_tap))
conn->seq_ack_to_tap = prev_ack_to_tap;
#else
if ((unsigned)SNDBUF_GET(conn) < SNDBUF_SMALL || tcp_rtt_dst_low(conn)
|| CONN_IS_CLOSING(conn) || (conn->flags & LOCAL) || force_seq) {
conn->seq_ack_to_tap = conn->seq_from_tap;
} else if (conn->seq_ack_to_tap != conn->seq_from_tap) {
if (!tinfo) {
tinfo = &tinfo_new;
if (getsockopt(s, SOL_TCP, TCP_INFO, tinfo, &sl))
return 0;
}
conn->seq_ack_to_tap = tinfo->tcpi_bytes_acked +
conn->seq_init_from_tap;
if (SEQ_LT(conn->seq_ack_to_tap, prev_ack_to_tap))
conn->seq_ack_to_tap = prev_ack_to_tap;
}
#endif /* !HAS_BYTES_ACKED */
if (!KERNEL_REPORTS_SND_WND(c)) {
tcp_get_sndbuf(conn);
new_wnd_to_tap = MIN(SNDBUF_GET(conn), MAX_WINDOW);
conn->wnd_to_tap = MIN(new_wnd_to_tap >> conn->ws_to_tap,
USHRT_MAX);
goto out;
}
if (!tinfo) {
if (prev_wnd_to_tap > WINDOW_DEFAULT) {
goto out;
}
tinfo = &tinfo_new;
if (getsockopt(s, SOL_TCP, TCP_INFO, tinfo, &sl)) {
goto out;
}
}
#ifdef HAS_SND_WND
if ((conn->flags & LOCAL) || tcp_rtt_dst_low(conn)) {
new_wnd_to_tap = tinfo->tcpi_snd_wnd;
} else {
tcp_get_sndbuf(conn);
new_wnd_to_tap = MIN((int)tinfo->tcpi_snd_wnd,
SNDBUF_GET(conn));
}
#endif
new_wnd_to_tap = MIN(new_wnd_to_tap, MAX_WINDOW);
if (!(conn->events & ESTABLISHED))
new_wnd_to_tap = MAX(new_wnd_to_tap, WINDOW_DEFAULT);
conn->wnd_to_tap = MIN(new_wnd_to_tap >> conn->ws_to_tap, USHRT_MAX);
/* Certain cppcheck versions, e.g. 2.12.0 have a bug where they think
* the MIN() above restricts conn->wnd_to_tap to be zero. That's
* clearly incorrect, but until the bug is fixed, work around it.
* https://bugzilla.redhat.com/show_bug.cgi?id=2240705
* https://sourceforge.net/p/cppcheck/discussion/general/thread/f5b1a00646/
*/
/* cppcheck-suppress [knownConditionTrueFalse, unmatchedSuppression] */
if (!conn->wnd_to_tap)
conn_flag(c, conn, ACK_TO_TAP_DUE);
out:
return new_wnd_to_tap != prev_wnd_to_tap ||
conn->seq_ack_to_tap != prev_ack_to_tap;
}
/**
* tcp_update_seqack_from_tap() - ACK number from tap and related flags/counters
* @c: Execution context
* @conn: Connection pointer
* @seq Current ACK sequence, host order
*/
static void tcp_update_seqack_from_tap(const struct ctx *c,
struct tcp_tap_conn *conn, uint32_t seq)
{
if (seq == conn->seq_to_tap)
conn_flag(c, conn, ~ACK_FROM_TAP_DUE);
if (SEQ_GT(seq, conn->seq_ack_from_tap)) {
/* Forward progress, but more data to acknowledge: reschedule */
if (SEQ_LT(seq, conn->seq_to_tap))
conn_flag(c, conn, ACK_FROM_TAP_DUE);
conn->retrans = 0;
conn->seq_ack_from_tap = seq;
}
}
/**
* tcp_send_flag() - Send segment with flags to tap (no payload)
* @c: Execution context
* @conn: Connection pointer
* @flags: TCP flags: if not set, send segment only if ACK is due
*
* Return: negative error code on connection reset, 0 otherwise
*/
static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
{
uint32_t prev_ack_to_tap = conn->seq_ack_to_tap;
uint32_t prev_wnd_to_tap = conn->wnd_to_tap;
struct tcp4_l2_flags_buf_t *b4 = NULL;
struct tcp6_l2_flags_buf_t *b6 = NULL;
struct tcp_info tinfo = { 0 };
socklen_t sl = sizeof(tinfo);
int s = conn->sock;
size_t optlen = 0;
struct iovec *iov;
struct tcphdr *th;
char *data;
void *p;
if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap) &&
!flags && conn->wnd_to_tap)
return 0;
if (getsockopt(s, SOL_TCP, TCP_INFO, &tinfo, &sl)) {
conn_event(c, conn, CLOSED);
return -ECONNRESET;
}
#ifdef HAS_SND_WND
if (!c->tcp.kernel_snd_wnd && tinfo.tcpi_snd_wnd)
c->tcp.kernel_snd_wnd = 1;
#endif
if (!(conn->flags & LOCAL))
tcp_rtt_dst_check(conn, &tinfo);
if (!tcp_update_seqack_wnd(c, conn, flags, &tinfo) && !flags)
return 0;
if (CONN_V4(conn)) {
iov = tcp4_l2_flags_iov + tcp4_l2_flags_buf_used;
p = b4 = tcp4_l2_flags_buf + tcp4_l2_flags_buf_used++;
th = &b4->th;
/* gcc 11.2 would complain on data = (char *)(th + 1); */
data = b4->opts;
} else {
iov = tcp6_l2_flags_iov + tcp6_l2_flags_buf_used;
p = b6 = tcp6_l2_flags_buf + tcp6_l2_flags_buf_used++;
th = &b6->th;
data = b6->opts;
}
if (flags & SYN) {
int mss;
/* Options: MSS, NOP and window scale (8 bytes) */
optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
*data++ = OPT_MSS;
*data++ = OPT_MSS_LEN;
if (c->mtu == -1) {
mss = tinfo.tcpi_snd_mss;
} else {
mss = c->mtu - sizeof(struct tcphdr);
if (CONN_V4(conn))
mss -= sizeof(struct iphdr);
else
mss -= sizeof(struct ipv6hdr);
if (c->low_wmem &&
!(conn->flags & LOCAL) && !tcp_rtt_dst_low(conn))
mss = MIN(mss, PAGE_SIZE);
else if (mss > PAGE_SIZE)
mss = ROUND_DOWN(mss, PAGE_SIZE);
}
*(uint16_t *)data = htons(MIN(USHRT_MAX, mss));
data += OPT_MSS_LEN - 2;
th->doff += OPT_MSS_LEN / 4;
conn->ws_to_tap = MIN(MAX_WS, tinfo.tcpi_snd_wscale);
*data++ = OPT_NOP;
*data++ = OPT_WS;
*data++ = OPT_WS_LEN;
*data++ = conn->ws_to_tap;
th->ack = !!(flags & ACK);
} else {
th->ack = !!(flags & (ACK | DUP_ACK)) ||
conn->seq_ack_to_tap != prev_ack_to_tap ||
!prev_wnd_to_tap;
}
th->doff = (sizeof(*th) + optlen) / 4;
th->rst = !!(flags & RST);
th->syn = !!(flags & SYN);
th->fin = !!(flags & FIN);
iov->iov_len = tcp_l2_buf_fill_headers(c, conn, p, optlen,
NULL, conn->seq_to_tap);
if (th->ack) {
if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap))
conn_flag(c, conn, ~ACK_TO_TAP_DUE);
else
conn_flag(c, conn, ACK_TO_TAP_DUE);
}
if (th->fin)
conn_flag(c, conn, ACK_FROM_TAP_DUE);
/* RFC 793, 3.1: "[...] and the first data octet is ISN+1." */
if (th->fin || th->syn)
conn->seq_to_tap++;
if (CONN_V4(conn)) {
if (flags & DUP_ACK) {
memcpy(b4 + 1, b4, sizeof(*b4));
(iov + 1)->iov_len = iov->iov_len;
tcp4_l2_flags_buf_used++;
}
if (tcp4_l2_flags_buf_used > ARRAY_SIZE(tcp4_l2_flags_buf) - 2)
tcp_l2_flags_buf_flush(c);
} else {
if (flags & DUP_ACK) {
memcpy(b6 + 1, b6, sizeof(*b6));
(iov + 1)->iov_len = iov->iov_len;
tcp6_l2_flags_buf_used++;
}
if (tcp6_l2_flags_buf_used > ARRAY_SIZE(tcp6_l2_flags_buf) - 2)
tcp_l2_flags_buf_flush(c);
}
return 0;
}
/**
* tcp_rst_do() - Reset a tap connection: send RST segment to tap, close socket
* @c: Execution context
* @conn: Connection pointer
*/
static void tcp_rst_do(struct ctx *c, struct tcp_tap_conn *conn)
{
if (conn->events == CLOSED)
return;
if (!tcp_send_flag(c, conn, RST))
conn_event(c, conn, CLOSED);
}
/**
* tcp_get_tap_ws() - Get Window Scaling option for connection from tap/guest
* @conn: Connection pointer
* @opts: Pointer to start of TCP options
* @optlen: Bytes in options: caller MUST ensure available length
*/
static void tcp_get_tap_ws(struct tcp_tap_conn *conn,
const char *opts, size_t optlen)
{
int ws = tcp_opt_get(opts, optlen, OPT_WS, NULL, NULL);
if (ws >= 0 && ws <= TCP_WS_MAX)
conn->ws_from_tap = ws;
else
conn->ws_from_tap = 0;
}
/**
* tcp_clamp_window() - Set new window for connection, clamp on socket
* @c: Execution context
* @conn: Connection pointer
* @window: Window value, host order, unscaled
*/
static void tcp_clamp_window(const struct ctx *c, struct tcp_tap_conn *conn,
unsigned wnd)
{
uint32_t prev_scaled = conn->wnd_from_tap << conn->ws_from_tap;
int s = conn->sock;
wnd <<= conn->ws_from_tap;
wnd = MIN(MAX_WINDOW, wnd);
if (conn->flags & WND_CLAMPED) {
if (prev_scaled == wnd)
return;
/* Discard +/- 1% updates to spare some syscalls. */
/* TODO: cppcheck, starting from commit b4d455df487c ("Fix
* 11349: FP negativeIndex for clamped array index (#4627)"),
* reports wnd > prev_scaled as always being true, see also:
*
* https://github.com/danmar/cppcheck/pull/4627
*
* drop this suppression once that's resolved.
*/
/* cppcheck-suppress [knownConditionTrueFalse, unmatchedSuppression] */
if ((wnd > prev_scaled && wnd * 99 / 100 < prev_scaled) ||
(wnd < prev_scaled && wnd * 101 / 100 > prev_scaled))
return;
}
conn->wnd_from_tap = MIN(wnd >> conn->ws_from_tap, USHRT_MAX);
if (setsockopt(s, SOL_TCP, TCP_WINDOW_CLAMP, &wnd, sizeof(wnd)))
trace("TCP: failed to set TCP_WINDOW_CLAMP on socket %i", s);
conn_flag(c, conn, WND_CLAMPED);
}
/**
* tcp_seq_init() - Calculate initial sequence number according to RFC 6528
* @c: Execution context
* @conn: TCP connection, with faddr, fport and eport populated
* @now: Current timestamp
*/
static void tcp_seq_init(const struct ctx *c, struct tcp_tap_conn *conn,
const struct timespec *now)
{
struct siphash_state state = SIPHASH_INIT(c->tcp.hash_secret);
union inany_addr aany;
uint64_t hash;
uint32_t ns;
if (CONN_V4(conn))
inany_from_af(&aany, AF_INET, &c->ip4.addr);
else
inany_from_af(&aany, AF_INET6, &c->ip6.addr);
inany_siphash_feed(&state, &conn->faddr);
inany_siphash_feed(&state, &aany);
hash = siphash_final(&state, 36,
(uint64_t)conn->fport << 16 | conn->eport);
/* 32ns ticks, overflows 32 bits every 137s */
ns = (now->tv_sec * 1000000000 + now->tv_nsec) >> 5;
conn->seq_to_tap = ((uint32_t)(hash >> 32) ^ (uint32_t)hash) + ns;
}
/**
* tcp_conn_pool_sock() - Get socket for new connection from pre-opened pool
* @pool: Pool of pre-opened sockets
*
* Return: socket number if available, negative code if pool is empty
*/
int tcp_conn_pool_sock(int pool[])
{
int s = -1, i;
for (i = 0; i < TCP_SOCK_POOL_SIZE; i++) {
SWAP(s, pool[i]);
if (s >= 0)
return s;
}
return -1;
}
/**
* tcp_conn_new_sock() - Open and prepare new socket for connection
* @c: Execution context
* @af: Address family
*
* Return: socket number on success, negative code if socket creation failed
*/
int tcp_conn_new_sock(const struct ctx *c, sa_family_t af)
{
int s;
s = socket(af, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
if (s > FD_REF_MAX) {
close(s);
return -EIO;
}
if (s < 0)
return -errno;
tcp_sock_set_bufsize(c, s);
return s;
}
/**
* tcp_conn_tap_mss() - Get MSS value advertised by tap/guest
* @conn: Connection pointer
* @opts: Pointer to start of TCP options
* @optlen: Bytes in options: caller MUST ensure available length
*
* Return: clamped MSS value
*/
static uint16_t tcp_conn_tap_mss(const struct tcp_tap_conn *conn,
const char *opts, size_t optlen)
{
unsigned int mss;
int ret;
if ((ret = tcp_opt_get(opts, optlen, OPT_MSS, NULL, NULL)) < 0)
mss = MSS_DEFAULT;
else
mss = ret;
if (CONN_V4(conn))
mss = MIN(MSS4, mss);
else
mss = MIN(MSS6, mss);
return MIN(mss, USHRT_MAX);
}
/**
* tcp_bind_outbound() - Bind socket to outbound address and interface if given
* @c: Execution context
* @s: Outbound TCP socket
* @af: Address family
*/
static void tcp_bind_outbound(const struct ctx *c, int s, sa_family_t af)
{
if (af == AF_INET) {
if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.addr_out)) {
struct sockaddr_in addr4 = {
.sin_family = AF_INET,
.sin_port = 0,
.sin_addr = c->ip4.addr_out,
};
if (bind(s, (struct sockaddr *)&addr4, sizeof(addr4))) {
debug("Can't bind IPv4 TCP socket address: %s",
strerror(errno));
}
}
if (*c->ip4.ifname_out) {
if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE,
c->ip4.ifname_out,
strlen(c->ip4.ifname_out))) {
debug("Can't bind IPv4 TCP socket to interface:"
" %s", strerror(errno));
}
}
} else if (af == AF_INET6) {
if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr_out)) {
struct sockaddr_in6 addr6 = {
.sin6_family = AF_INET6,
.sin6_port = 0,
.sin6_addr = c->ip6.addr_out,
};
if (bind(s, (struct sockaddr *)&addr6, sizeof(addr6))) {
debug("Can't bind IPv6 TCP socket address: %s",
strerror(errno));
}
}
if (*c->ip6.ifname_out) {
if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE,
c->ip6.ifname_out,
strlen(c->ip6.ifname_out))) {
debug("Can't bind IPv6 TCP socket to interface:"
" %s", strerror(errno));
}
}
}
}
/**
* tcp_conn_from_tap() - Handle connection request (SYN segment) from tap
* @c: Execution context
* @af: Address family, AF_INET or AF_INET6
* @saddr: Source address, pointer to in_addr or in6_addr
* @daddr: Destination address, pointer to in_addr or in6_addr
* @th: TCP header from tap: caller MUST ensure it's there
* @opts: Pointer to start of options
* @optlen: Bytes in options: caller MUST ensure available length
* @now: Current timestamp
*/
static void tcp_conn_from_tap(struct ctx *c,
int af, const void *saddr, const void *daddr,
const struct tcphdr *th, const char *opts,
size_t optlen, const struct timespec *now)
{
int *pool = af == AF_INET6 ? init_sock_pool6 : init_sock_pool4;
struct sockaddr_in addr4 = {
.sin_family = AF_INET,
.sin_port = th->dest,
.sin_addr = *(struct in_addr *)daddr,
};
struct sockaddr_in6 addr6 = {
.sin6_family = AF_INET6,
.sin6_port = th->dest,
.sin6_addr = *(struct in6_addr *)daddr,
};
const struct sockaddr *sa;
struct tcp_tap_conn *conn;
socklen_t sl;
int s, mss;
(void)saddr;
if (c->tcp.conn_count >= TCP_MAX_CONNS)
return;
if ((s = tcp_conn_pool_sock(pool)) < 0)
if ((s = tcp_conn_new_sock(c, af)) < 0)
return;
if (!c->no_map_gw) {
if (af == AF_INET && IN4_ARE_ADDR_EQUAL(daddr, &c->ip4.gw))
addr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
if (af == AF_INET6 && IN6_ARE_ADDR_EQUAL(daddr, &c->ip6.gw))
addr6.sin6_addr = in6addr_loopback;
}
if (af == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&addr6.sin6_addr)) {
struct sockaddr_in6 addr6_ll = {
.sin6_family = AF_INET6,
.sin6_addr = c->ip6.addr_ll,
.sin6_scope_id = c->ifi6,
};
if (bind(s, (struct sockaddr *)&addr6_ll, sizeof(addr6_ll))) {
close(s);
return;
}
}
conn = CONN(c->tcp.conn_count++);
conn->c.spliced = false;
conn->sock = s;
conn->timer = -1;
conn_event(c, conn, TAP_SYN_RCVD);
conn->wnd_to_tap = WINDOW_DEFAULT;
mss = tcp_conn_tap_mss(conn, opts, optlen);
if (setsockopt(s, SOL_TCP, TCP_MAXSEG, &mss, sizeof(mss)))
trace("TCP: failed to set TCP_MAXSEG on socket %i", s);
MSS_SET(conn, mss);
tcp_get_tap_ws(conn, opts, optlen);
/* RFC 7323, 2.2: first value is not scaled. Also, don't clamp yet, to
* avoid getting a zero scale just because we set a small window now.
*/
if (!(conn->wnd_from_tap = (htons(th->window) >> conn->ws_from_tap)))
conn->wnd_from_tap = 1;
inany_from_af(&conn->faddr, af, daddr);
if (af == AF_INET) {
sa = (struct sockaddr *)&addr4;
sl = sizeof(addr4);
} else {
sa = (struct sockaddr *)&addr6;
sl = sizeof(addr6);
}
conn->fport = ntohs(th->dest);
conn->eport = ntohs(th->source);
conn->seq_init_from_tap = ntohl(th->seq);
conn->seq_from_tap = conn->seq_init_from_tap + 1;
conn->seq_ack_to_tap = conn->seq_from_tap;
tcp_seq_init(c, conn, now);
conn->seq_ack_from_tap = conn->seq_to_tap;
tcp_hash_insert(c, conn);
if (!bind(s, sa, sl)) {
tcp_rst(c, conn); /* Nobody is listening then */
return;
}
if (errno != EADDRNOTAVAIL && errno != EACCES)
conn_flag(c, conn, LOCAL);
if ((af == AF_INET && !IN4_IS_ADDR_LOOPBACK(&addr4.sin_addr)) ||
(af == AF_INET6 && !IN6_IS_ADDR_LOOPBACK(&addr6.sin6_addr) &&
!IN6_IS_ADDR_LINKLOCAL(&addr6.sin6_addr)))
tcp_bind_outbound(c, s, af);
if (connect(s, sa, sl)) {
if (errno != EINPROGRESS) {
tcp_rst(c, conn);
return;
}
tcp_get_sndbuf(conn);
} else {
tcp_get_sndbuf(conn);
if (tcp_send_flag(c, conn, SYN | ACK))
return;
conn_event(c, conn, TAP_SYN_ACK_SENT);
}
tcp_epoll_ctl(c, conn);
}
/**
* tcp_sock_consume() - Consume (discard) data from buffer
* @conn: Connection pointer
* @ack_seq: ACK sequence, host order
*
* Return: 0 on success, negative error code from recv() on failure
*/
static int tcp_sock_consume(const struct tcp_tap_conn *conn, uint32_t ack_seq)
{
/* Simply ignore out-of-order ACKs: we already consumed the data we
* needed from the buffer, and we won't rewind back to a lower ACK
* sequence.
*/
if (SEQ_LE(ack_seq, conn->seq_ack_from_tap))
return 0;
/* cppcheck-suppress [nullPointer, unmatchedSuppression] */
if (recv(conn->sock, NULL, ack_seq - conn->seq_ack_from_tap,
MSG_DONTWAIT | MSG_TRUNC) < 0)
return -errno;
return 0;
}
/**
* tcp_data_to_tap() - Finalise (queue) highest-numbered scatter-gather buffer
* @c: Execution context
* @conn: Connection pointer
* @plen: Payload length at L4
* @no_csum: Don't compute IPv4 checksum, use the one from previous buffer
* @seq: Sequence number to be sent
* @now: Current timestamp
*/
static void tcp_data_to_tap(const struct ctx *c, struct tcp_tap_conn *conn,
ssize_t plen, int no_csum, uint32_t seq)
{
struct iovec *iov;
if (CONN_V4(conn)) {
struct tcp4_l2_buf_t *b = &tcp4_l2_buf[tcp4_l2_buf_used];
const uint16_t *check = no_csum ? &(b - 1)->iph.check : NULL;
iov = tcp4_l2_iov + tcp4_l2_buf_used++;
iov->iov_len = tcp_l2_buf_fill_headers(c, conn, b, plen,
check, seq);
if (tcp4_l2_buf_used > ARRAY_SIZE(tcp4_l2_buf) - 1)
tcp_l2_data_buf_flush(c);
} else if (CONN_V6(conn)) {
struct tcp6_l2_buf_t *b = &tcp6_l2_buf[tcp6_l2_buf_used];
iov = tcp6_l2_iov + tcp6_l2_buf_used++;
iov->iov_len = tcp_l2_buf_fill_headers(c, conn, b, plen,
NULL, seq);
if (tcp6_l2_buf_used > ARRAY_SIZE(tcp6_l2_buf) - 1)
tcp_l2_data_buf_flush(c);
}
}
/**
* tcp_data_from_sock() - Handle new data from socket, queue to tap, in window
* @c: Execution context
* @conn: Connection pointer
*
* Return: negative on connection reset, 0 otherwise
*
* #syscalls recvmsg
*/
static int tcp_data_from_sock(struct ctx *c, struct tcp_tap_conn *conn)
{
uint32_t wnd_scaled = conn->wnd_from_tap << conn->ws_from_tap;
int fill_bufs, send_bufs = 0, last_len, iov_rem = 0;
int sendlen, len, plen, v4 = CONN_V4(conn);
int s = conn->sock, i, ret = 0;
struct msghdr mh_sock = { 0 };
uint16_t mss = MSS_GET(conn);
uint32_t already_sent;
struct iovec *iov;
already_sent = conn->seq_to_tap - conn->seq_ack_from_tap;
if (SEQ_LT(already_sent, 0)) {
/* RFC 761, section 2.1. */
trace("TCP: ACK sequence gap: ACK for %u, sent: %u",
conn->seq_ack_from_tap, conn->seq_to_tap);
conn->seq_to_tap = conn->seq_ack_from_tap;
already_sent = 0;
}
if (!wnd_scaled || already_sent >= wnd_scaled) {
conn_flag(c, conn, STALLED);
conn_flag(c, conn, ACK_FROM_TAP_DUE);
return 0;
}
/* Set up buffer descriptors we'll fill completely and partially. */
fill_bufs = DIV_ROUND_UP(wnd_scaled - already_sent, mss);
if (fill_bufs > TCP_FRAMES) {
fill_bufs = TCP_FRAMES;
iov_rem = 0;
} else {
iov_rem = (wnd_scaled - already_sent) % mss;
}
mh_sock.msg_iov = iov_sock;
mh_sock.msg_iovlen = fill_bufs + 1;
iov_sock[0].iov_base = tcp_buf_discard;
iov_sock[0].iov_len = already_sent;
if (( v4 && tcp4_l2_buf_used + fill_bufs > ARRAY_SIZE(tcp4_l2_buf)) ||
(!v4 && tcp6_l2_buf_used + fill_bufs > ARRAY_SIZE(tcp6_l2_buf))) {
tcp_l2_data_buf_flush(c);
/* Silence Coverity CWE-125 false positive */
tcp4_l2_buf_used = tcp6_l2_buf_used = 0;
}
for (i = 0, iov = iov_sock + 1; i < fill_bufs; i++, iov++) {
if (v4)
iov->iov_base = &tcp4_l2_buf[tcp4_l2_buf_used + i].data;
else
iov->iov_base = &tcp6_l2_buf[tcp6_l2_buf_used + i].data;
iov->iov_len = mss;
}
if (iov_rem)
iov_sock[fill_bufs].iov_len = iov_rem;
/* Receive into buffers, don't dequeue until acknowledged by guest. */
do
len = recvmsg(s, &mh_sock, MSG_PEEK);
while (len < 0 && errno == EINTR);
if (len < 0)
goto err;
if (!len) {
if ((conn->events & (SOCK_FIN_RCVD | TAP_FIN_SENT)) == SOCK_FIN_RCVD) {
if ((ret = tcp_send_flag(c, conn, FIN | ACK))) {
tcp_rst(c, conn);
return ret;
}
conn_event(c, conn, TAP_FIN_SENT);
}
return 0;
}
sendlen = len - already_sent;
if (sendlen <= 0) {
conn_flag(c, conn, STALLED);
return 0;
}
conn_flag(c, conn, ~STALLED);
send_bufs = DIV_ROUND_UP(sendlen, mss);
last_len = sendlen - (send_bufs - 1) * mss;
/* Likely, some new data was acked too. */
tcp_update_seqack_wnd(c, conn, 0, NULL);
/* Finally, queue to tap */
plen = mss;
for (i = 0; i < send_bufs; i++) {
int no_csum = i && i != send_bufs - 1 && tcp4_l2_buf_used;
if (i == send_bufs - 1)
plen = last_len;
tcp_data_to_tap(c, conn, plen, no_csum, conn->seq_to_tap);
conn->seq_to_tap += plen;
}
conn_flag(c, conn, ACK_FROM_TAP_DUE);
return 0;
err:
if (errno != EAGAIN && errno != EWOULDBLOCK) {
ret = -errno;
tcp_rst(c, conn);
}
return ret;
}
/**
* tcp_data_from_tap() - tap/guest data for established connection
* @c: Execution context
* @conn: Connection pointer
* @p: Pool of TCP packets, with TCP headers
* @idx: Index of first data packet in pool
*
* #syscalls sendmsg
*
* Return: count of consumed packets
*/
static int tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn,
const struct pool *p, int idx)
{
int i, iov_i, ack = 0, fin = 0, retr = 0, keep = -1, partial_send = 0;
uint16_t max_ack_seq_wnd = conn->wnd_from_tap;
uint32_t max_ack_seq = conn->seq_ack_from_tap;
uint32_t seq_from_tap = conn->seq_from_tap;
struct msghdr mh = { .msg_iov = tcp_iov };
size_t len;
ssize_t n;
if (conn->events == CLOSED)
return p->count - idx;
ASSERT(conn->events & ESTABLISHED);
for (i = idx, iov_i = 0; i < (int)p->count; i++) {
uint32_t seq, seq_offset, ack_seq;
struct tcphdr *th;
char *data;
size_t off;
th = packet_get(p, i, 0, sizeof(*th), &len);
if (!th)
return -1;
len += sizeof(*th);
off = th->doff * 4UL;
if (off < sizeof(*th) || off > len)
return -1;
if (th->rst) {
conn_event(c, conn, CLOSED);
return 1;
}
len -= off;
data = packet_get(p, i, off, len, NULL);
if (!data)
continue;
seq = ntohl(th->seq);
ack_seq = ntohl(th->ack_seq);
if (th->ack) {
ack = 1;
if (SEQ_GE(ack_seq, conn->seq_ack_from_tap) &&
SEQ_GE(ack_seq, max_ack_seq)) {
/* Fast re-transmit */
retr = !len && !th->fin &&
ack_seq == max_ack_seq &&
ntohs(th->window) == max_ack_seq_wnd;
max_ack_seq_wnd = ntohs(th->window);
max_ack_seq = ack_seq;
}
}
if (th->fin)
fin = 1;
if (!len)
continue;
seq_offset = seq_from_tap - seq;
/* Use data from this buffer only in these two cases:
*
* , seq_from_tap , seq_from_tap
* |--------| <-- len |--------| <-- len
* '----' <-- offset ' <-- offset
* ^ seq ^ seq
* (offset >= 0, seq + len > seq_from_tap)
*
* discard in these two cases:
* , seq_from_tap , seq_from_tap
* |--------| <-- len |--------| <-- len
* '--------' <-- offset '-----| <- offset
* ^ seq ^ seq
* (offset >= 0, seq + len <= seq_from_tap)
*
* keep, look for another buffer, then go back, in this case:
* , seq_from_tap
* |--------| <-- len
* '===' <-- offset
* ^ seq
* (offset < 0)
*/
if (SEQ_GE(seq_offset, 0) && SEQ_LE(seq + len, seq_from_tap))
continue;
if (SEQ_LT(seq_offset, 0)) {
if (keep == -1)
keep = i;
continue;
}
tcp_iov[iov_i].iov_base = data + seq_offset;
tcp_iov[iov_i].iov_len = len - seq_offset;
seq_from_tap += tcp_iov[iov_i].iov_len;
iov_i++;
if (keep == i)
keep = -1;
if (keep != -1)
i = keep - 1;
}
tcp_clamp_window(c, conn, max_ack_seq_wnd);
/* On socket flush failure, pretend there was no ACK, try again later */
if (ack && !tcp_sock_consume(conn, max_ack_seq))
tcp_update_seqack_from_tap(c, conn, max_ack_seq);
if (retr) {
trace("TCP: fast re-transmit, ACK: %u, previous sequence: %u",
max_ack_seq, conn->seq_to_tap);
conn->seq_ack_from_tap = max_ack_seq;
conn->seq_to_tap = max_ack_seq;
tcp_data_from_sock(c, conn);
}
if (!iov_i)
goto out;
mh.msg_iovlen = iov_i;
eintr:
n = sendmsg(conn->sock, &mh, MSG_DONTWAIT | MSG_NOSIGNAL);
if (n < 0) {
if (errno == EPIPE) {
/* Here's the wrap, said the tap.
* In my pocket, said the socket.
* Then swiftly looked away and left.
*/
conn->seq_from_tap = seq_from_tap;
tcp_send_flag(c, conn, ACK);
}
if (errno == EINTR)
goto eintr;
if (errno == EAGAIN || errno == EWOULDBLOCK) {
tcp_send_flag(c, conn, ACK_IF_NEEDED);
return p->count - idx;
}
return -1;
}
if (n < (int)(seq_from_tap - conn->seq_from_tap)) {
partial_send = 1;
conn->seq_from_tap += n;
tcp_send_flag(c, conn, ACK_IF_NEEDED);
} else {
conn->seq_from_tap += n;
}
out:
if (keep != -1) {
/* We use an 8-bit approximation here: the associated risk is
* that we skip a duplicate ACK on 8-bit sequence number
* collision. Fast retransmit is a SHOULD in RFC 5681, 3.2.
*/
if (conn->seq_dup_ack_approx != (conn->seq_from_tap & 0xff)) {
conn->seq_dup_ack_approx = conn->seq_from_tap & 0xff;
tcp_send_flag(c, conn, DUP_ACK);
}
return p->count - idx;
}
if (ack && conn->events & TAP_FIN_SENT &&
conn->seq_ack_from_tap == conn->seq_to_tap)
conn_event(c, conn, TAP_FIN_ACKED);
if (fin && !partial_send) {
conn->seq_from_tap++;
conn_event(c, conn, TAP_FIN_RCVD);
} else {
tcp_send_flag(c, conn, ACK_IF_NEEDED);
}
return p->count - idx;
}
/**
* tcp_conn_from_sock_finish() - Complete connection setup after connect()
* @c: Execution context
* @conn: Connection pointer
* @th: TCP header of SYN, ACK segment: caller MUST ensure it's there
* @opts: Pointer to start of options
* @optlen: Bytes in options: caller MUST ensure available length
*/
static void tcp_conn_from_sock_finish(struct ctx *c, struct tcp_tap_conn *conn,
const struct tcphdr *th,
const char *opts, size_t optlen)
{
tcp_clamp_window(c, conn, ntohs(th->window));
tcp_get_tap_ws(conn, opts, optlen);
/* First value is not scaled */
if (!(conn->wnd_from_tap >>= conn->ws_from_tap))
conn->wnd_from_tap = 1;
MSS_SET(conn, tcp_conn_tap_mss(conn, opts, optlen));
conn->seq_init_from_tap = ntohl(th->seq) + 1;
conn->seq_from_tap = conn->seq_init_from_tap;
conn->seq_ack_to_tap = conn->seq_from_tap;
conn_event(c, conn, ESTABLISHED);
/* The client might have sent data already, which we didn't
* dequeue waiting for SYN,ACK from tap -- check now.
*/
tcp_data_from_sock(c, conn);
tcp_send_flag(c, conn, ACK);
}
/**
* tcp_tap_handler() - Handle packets from tap and state transitions
* @c: Execution context
* @af: Address family, AF_INET or AF_INET6
* @saddr: Source address
* @daddr: Destination address
* @p: Pool of TCP packets, with TCP headers
* @idx: Index of first packet in pool to process
* @now: Current timestamp
*
* Return: count of consumed packets
*/
int tcp_tap_handler(struct ctx *c, int af, const void *saddr, const void *daddr,
const struct pool *p, int idx, const struct timespec *now)
{
struct tcp_tap_conn *conn;
size_t optlen, len;
struct tcphdr *th;
int ack_due = 0;
char *opts;
int count;
th = packet_get(p, idx, 0, sizeof(*th), &len);
if (!th)
return 1;
len += sizeof(*th);
optlen = th->doff * 4UL - sizeof(*th);
/* Static checkers might fail to see this: */
optlen = MIN(optlen, ((1UL << 4) /* from doff width */ - 6) * 4UL);
opts = packet_get(p, idx, sizeof(*th), optlen, NULL);
conn = tcp_hash_lookup(c, af, daddr, htons(th->source), htons(th->dest));
/* New connection from tap */
if (!conn) {
if (opts && th->syn && !th->ack)
tcp_conn_from_tap(c, af, saddr, daddr, th,
opts, optlen, now);
return 1;
}
trace("TCP: packet length %lu from tap for index %lu", len, CONN_IDX(conn));
if (th->rst) {
conn_event(c, conn, CLOSED);
return 1;
}
if (th->ack && !(conn->events & ESTABLISHED))
tcp_update_seqack_from_tap(c, conn, ntohl(th->ack_seq));
conn_flag(c, conn, ~STALLED);
/* Establishing connection from socket */
if (conn->events & SOCK_ACCEPTED) {
if (th->syn && th->ack && !th->fin) {
tcp_conn_from_sock_finish(c, conn, th, opts, optlen);
return 1;
}
goto reset;
}
/* Establishing connection from tap */
if (conn->events & TAP_SYN_RCVD) {
if (!(conn->events & TAP_SYN_ACK_SENT))
goto reset;
conn_event(c, conn, ESTABLISHED);
if (th->fin) {
conn->seq_from_tap++;
shutdown(conn->sock, SHUT_WR);
tcp_send_flag(c, conn, ACK);
conn_event(c, conn, SOCK_FIN_SENT);
return 1;
}
if (!th->ack)
goto reset;
tcp_clamp_window(c, conn, ntohs(th->window));
tcp_data_from_sock(c, conn);
if (p->count - idx == 1)
return 1;
}
/* Established connections not accepting data from tap */
if (conn->events & TAP_FIN_RCVD) {
tcp_update_seqack_from_tap(c, conn, ntohl(th->ack_seq));
if (conn->events & SOCK_FIN_RCVD &&
conn->seq_ack_from_tap == conn->seq_to_tap)
conn_event(c, conn, CLOSED);
return 1;
}
/* Established connections accepting data from tap */
count = tcp_data_from_tap(c, conn, p, idx);
if (count == -1)
goto reset;
if (conn->seq_ack_to_tap != conn->seq_from_tap)
ack_due = 1;
if ((conn->events & TAP_FIN_RCVD) && !(conn->events & SOCK_FIN_SENT)) {
shutdown(conn->sock, SHUT_WR);
conn_event(c, conn, SOCK_FIN_SENT);
tcp_send_flag(c, conn, ACK);
ack_due = 0;
}
if (ack_due)
conn_flag(c, conn, ACK_TO_TAP_DUE);
return count;
reset:
/* Something's gone wrong, so reset the connection. We discard
* remaining packets in the batch, since they'd be invalidated when our
* RST is received, even if otherwise good.
*/
tcp_rst(c, conn);
return p->count - idx;
}
/**
* tcp_connect_finish() - Handle completion of connect() from EPOLLOUT event
* @c: Execution context
* @conn: Connection pointer
*/
static void tcp_connect_finish(struct ctx *c, struct tcp_tap_conn *conn)
{
socklen_t sl;
int so;
sl = sizeof(so);
if (getsockopt(conn->sock, SOL_SOCKET, SO_ERROR, &so, &sl) || so) {
tcp_rst(c, conn);
return;
}
if (tcp_send_flag(c, conn, SYN | ACK))
return;
conn_event(c, conn, TAP_SYN_ACK_SENT);
conn_flag(c, conn, ACK_FROM_TAP_DUE);
}
/**
* tcp_snat_inbound() - Translate source address for inbound data if needed
* @c: Execution context
* @addr: Source address of inbound packet/connection
*/
static void tcp_snat_inbound(const struct ctx *c, union inany_addr *addr)
{
struct in_addr *addr4 = inany_v4(addr);
if (addr4) {
if (IN4_IS_ADDR_LOOPBACK(addr4) ||
IN4_IS_ADDR_UNSPECIFIED(addr4) ||
IN4_ARE_ADDR_EQUAL(addr4, &c->ip4.addr_seen))
*addr4 = c->ip4.gw;
} else {
struct in6_addr *addr6 = &addr->a6;
if (IN6_IS_ADDR_LOOPBACK(addr6) ||
IN6_ARE_ADDR_EQUAL(addr6, &c->ip6.addr_seen) ||
IN6_ARE_ADDR_EQUAL(addr6, &c->ip6.addr)) {
if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
*addr6 = c->ip6.gw;
else
*addr6 = c->ip6.addr_ll;
}
}
}
/**
* tcp_tap_conn_from_sock() - Initialize state for non-spliced connection
* @c: Execution context
* @ref: epoll reference of listening socket
* @conn: connection structure to initialize
* @s: Accepted socket
* @sa: Peer socket address (from accept())
* @now: Current timestamp
*/
static void tcp_tap_conn_from_sock(struct ctx *c,
union tcp_listen_epoll_ref ref,
struct tcp_tap_conn *conn, int s,
const struct sockaddr *sa,
const struct timespec *now)
{
conn->c.spliced = false;
conn->sock = s;
conn->timer = -1;
conn->ws_to_tap = conn->ws_from_tap = 0;
conn_event(c, conn, SOCK_ACCEPTED);
inany_from_sockaddr(&conn->faddr, &conn->fport, sa);
conn->eport = ref.port;
tcp_snat_inbound(c, &conn->faddr);
tcp_seq_init(c, conn, now);
tcp_hash_insert(c, conn);
conn->seq_ack_from_tap = conn->seq_to_tap;
conn->wnd_from_tap = WINDOW_DEFAULT;
tcp_send_flag(c, conn, SYN);
conn_flag(c, conn, ACK_FROM_TAP_DUE);
tcp_get_sndbuf(conn);
}
/**
* tcp_listen_handler() - Handle new connection request from listening socket
* @c: Execution context
* @ref: epoll reference of listening socket
* @now: Current timestamp
*/
void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
const struct timespec *now)
{
struct sockaddr_storage sa;
socklen_t sl = sizeof(sa);
union tcp_conn *conn;
int s;
if (c->no_tcp || c->tcp.conn_count >= TCP_MAX_CONNS)
return;
s = accept4(ref.fd, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK);
if (s < 0)
return;
conn = tc + c->tcp.conn_count++;
if (c->mode == MODE_PASTA &&
tcp_splice_conn_from_sock(c, ref.tcp_listen, &conn->splice,
s, (struct sockaddr *)&sa))
return;
tcp_tap_conn_from_sock(c, ref.tcp_listen, &conn->tap, s,
(struct sockaddr *)&sa, now);
}
/**
* tcp_timer_handler() - timerfd events: close, send ACK, retransmit, or reset
* @c: Execution context
* @ref: epoll reference of timer (not connection)
*
* #syscalls timerfd_gettime
*/
void tcp_timer_handler(struct ctx *c, union epoll_ref ref)
{
struct tcp_tap_conn *conn = conn_at_idx(ref.tcp.index);
struct itimerspec check_armed = { { 0 }, { 0 } };
if (c->no_tcp || !conn)
return;
/* We don't reset timers on ~ACK_FROM_TAP_DUE, ~ACK_TO_TAP_DUE. If the
* timer is currently armed, this event came from a previous setting,
* and we just set the timer to a new point in the future: discard it.
*/
timerfd_gettime(conn->timer, &check_armed);
if (check_armed.it_value.tv_sec || check_armed.it_value.tv_nsec)
return;
if (conn->flags & ACK_TO_TAP_DUE) {
tcp_send_flag(c, conn, ACK_IF_NEEDED);
tcp_timer_ctl(c, conn);
} else if (conn->flags & ACK_FROM_TAP_DUE) {
if (!(conn->events & ESTABLISHED)) {
debug("TCP: index %li, handshake timeout", CONN_IDX(conn));
tcp_rst(c, conn);
} else if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED)) {
debug("TCP: index %li, FIN timeout", CONN_IDX(conn));
tcp_rst(c, conn);
} else if (conn->retrans == TCP_MAX_RETRANS) {
debug("TCP: index %li, retransmissions count exceeded",
CONN_IDX(conn));
tcp_rst(c, conn);
} else {
debug("TCP: index %li, ACK timeout, retry", CONN_IDX(conn));
conn->retrans++;
conn->seq_to_tap = conn->seq_ack_from_tap;
tcp_data_from_sock(c, conn);
tcp_timer_ctl(c, conn);
}
} else {
struct itimerspec new = { { 0 }, { ACT_TIMEOUT, 0 } };
struct itimerspec old = { { 0 }, { 0 } };
/* Activity timeout: if it was already set, reset the
* connection, otherwise, it was a left-over from ACK_TO_TAP_DUE
* or ACK_FROM_TAP_DUE, so just set the long timeout in that
* case. This avoids having to preemptively reset the timer on
* ~ACK_TO_TAP_DUE or ~ACK_FROM_TAP_DUE.
*/
timerfd_settime(conn->timer, 0, &new, &old);
if (old.it_value.tv_sec == ACT_TIMEOUT) {
debug("TCP: index %li, activity timeout", CONN_IDX(conn));
tcp_rst(c, conn);
}
}
}
/**
* tcp_tap_sock_handler() - Handle new data from non-spliced socket
* @c: Execution context
* @conn: Connection state
* @events: epoll events bitmap
*/
static void tcp_tap_sock_handler(struct ctx *c, struct tcp_tap_conn *conn,
uint32_t events)
{
if (conn->events == CLOSED)
return;
if (events & EPOLLERR) {
tcp_rst(c, conn);
return;
}
if ((conn->events & TAP_FIN_SENT) && (events & EPOLLHUP)) {
conn_event(c, conn, CLOSED);
return;
}
if (conn->events & ESTABLISHED) {
if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED))
conn_event(c, conn, CLOSED);
if (events & (EPOLLRDHUP | EPOLLHUP))
conn_event(c, conn, SOCK_FIN_RCVD);
if (events & EPOLLIN)
tcp_data_from_sock(c, conn);
if (events & EPOLLOUT)
tcp_update_seqack_wnd(c, conn, 0, NULL);
return;
}
/* EPOLLHUP during handshake: reset */
if (events & EPOLLHUP) {
tcp_rst(c, conn);
return;
}
/* Data during handshake tap-side: check later */
if (conn->events & SOCK_ACCEPTED)
return;
if (conn->events == TAP_SYN_RCVD) {
if (events & EPOLLOUT)
tcp_connect_finish(c, conn);
/* Data? Check later */
}
}
/**
* tcp_sock_handler() - Handle new data from socket, or timerfd event
* @c: Execution context
* @ref: epoll reference
* @events: epoll events bitmap
*/
void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events)
{
union tcp_conn *conn = tc + ref.tcp.index;
if (conn->c.spliced)
tcp_splice_sock_handler(c, &conn->splice, ref.fd, events);
else
tcp_tap_sock_handler(c, &conn->tap, events);
}
/**
* tcp_sock_init_af() - Initialise listening socket for a given af and port
* @c: Execution context
* @af: Address family to listen on
* @port: Port, host order
* @addr: Pointer to address for binding, NULL if not configured
* @ifname: Name of interface to bind to, NULL if not configured
*
* Return: fd for the new listening socket, negative error code on failure
*/
static int tcp_sock_init_af(const struct ctx *c, int af, in_port_t port,
const struct in_addr *addr, const char *ifname)
{
union tcp_listen_epoll_ref tref = {
.port = port + c->tcp.fwd_in.delta[port],
};
int s;
s = sock_l4(c, af, IPPROTO_TCP, addr, ifname, port, tref.u32);
if (c->tcp.fwd_in.mode == FWD_AUTO) {
if (af == AF_INET || af == AF_UNSPEC)
tcp_sock_init_ext[port][V4] = s < 0 ? -1 : s;
if (af == AF_INET6 || af == AF_UNSPEC)
tcp_sock_init_ext[port][V6] = s < 0 ? -1 : s;
}
if (s < 0)
return s;
tcp_sock_set_bufsize(c, s);
return s;
}
/**
* tcp_sock_init() - Create listening sockets for a given host ("inbound") port
* @c: Execution context
* @af: Address family to select a specific IP version, or AF_UNSPEC
* @addr: Pointer to address for binding, NULL if not configured
* @ifname: Name of interface to bind to, NULL if not configured
* @port: Port, host order
*
* Return: 0 on (partial) success, negative error code on (complete) failure
*/
int tcp_sock_init(const struct ctx *c, sa_family_t af, const void *addr,
const char *ifname, in_port_t port)
{
int r4 = FD_REF_MAX + 1, r6 = FD_REF_MAX + 1;
if (af == AF_UNSPEC && c->ifi4 && c->ifi6)
/* Attempt to get a dual stack socket */
if (tcp_sock_init_af(c, AF_UNSPEC, port, addr, ifname) >= 0)
return 0;
/* Otherwise create a socket per IP version */
if ((af == AF_INET || af == AF_UNSPEC) && c->ifi4)
r4 = tcp_sock_init_af(c, AF_INET, port, addr, ifname);
if ((af == AF_INET6 || af == AF_UNSPEC) && c->ifi6)
r6 = tcp_sock_init_af(c, AF_INET6, port, addr, ifname);
if (IN_INTERVAL(0, FD_REF_MAX, r4) || IN_INTERVAL(0, FD_REF_MAX, r6))
return 0;
return r4 < 0 ? r4 : r6;
}
/**
* tcp_ns_sock_init4() - Init socket to listen for outbound IPv4 connections
* @c: Execution context
* @port: Port, host order
*/
static void tcp_ns_sock_init4(const struct ctx *c, in_port_t port)
{
union tcp_listen_epoll_ref tref = {
.port = port + c->tcp.fwd_out.delta[port],
.ns = true,
};
struct in_addr loopback = { htonl(INADDR_LOOPBACK) };
int s;
ASSERT(c->mode == MODE_PASTA);
s = sock_l4(c, AF_INET, IPPROTO_TCP, &loopback, NULL, port, tref.u32);
if (s >= 0)
tcp_sock_set_bufsize(c, s);
else
s = -1;
if (c->tcp.fwd_out.mode == FWD_AUTO)
tcp_sock_ns[port][V4] = s;
}
/**
* tcp_ns_sock_init6() - Init socket to listen for outbound IPv6 connections
* @c: Execution context
* @port: Port, host order
*/
static void tcp_ns_sock_init6(const struct ctx *c, in_port_t port)
{
union tcp_listen_epoll_ref tref = {
.port = port + c->tcp.fwd_out.delta[port],
.ns = true,
};
int s;
ASSERT(c->mode == MODE_PASTA);
s = sock_l4(c, AF_INET6, IPPROTO_TCP, &in6addr_loopback, NULL, port,
tref.u32);
if (s >= 0)
tcp_sock_set_bufsize(c, s);
else
s = -1;
if (c->tcp.fwd_out.mode == FWD_AUTO)
tcp_sock_ns[port][V6] = s;
}
/**
* tcp_ns_sock_init() - Init socket to listen for spliced outbound connections
* @c: Execution context
* @port: Port, host order
*/
void tcp_ns_sock_init(const struct ctx *c, in_port_t port)
{
if (c->ifi4)
tcp_ns_sock_init4(c, port);
if (c->ifi6)
tcp_ns_sock_init6(c, port);
}
/**
* tcp_ns_socks_init() - Bind sockets in namespace for outbound connections
* @arg: Execution context
*
* Return: 0
*/
static int tcp_ns_socks_init(void *arg)
{
struct ctx *c = (struct ctx *)arg;
unsigned port;
ns_enter(c);
for (port = 0; port < NUM_PORTS; port++) {
if (!bitmap_isset(c->tcp.fwd_out.map, port))
continue;
tcp_ns_sock_init(c, port);
}
return 0;
}
/**
* tcp_sock_refill_pool() - Refill one pool of pre-opened sockets
* @c: Execution context
* @pool: Pool of sockets to refill
* @af: Address family to use
*/
void tcp_sock_refill_pool(const struct ctx *c, int pool[], int af)
{
int i;
for (i = 0; i < TCP_SOCK_POOL_SIZE; i++) {
if (pool[i] >= 0)
break;
pool[i] = tcp_conn_new_sock(c, af);
}
}
/**
* tcp_sock_refill_init() - Refill pools of pre-opened sockets in init ns
* @c: Execution context
*/
static void tcp_sock_refill_init(const struct ctx *c)
{
if (c->ifi4)
tcp_sock_refill_pool(c, init_sock_pool4, AF_INET);
if (c->ifi6)
tcp_sock_refill_pool(c, init_sock_pool6, AF_INET6);
}
/**
* tcp_init() - Get initial sequence, hash secret, initialise per-socket data
* @c: Execution context
*
* Return: 0, doesn't return on failure
*/
int tcp_init(struct ctx *c)
{
int i;
#ifndef HAS_GETRANDOM
int dev_random = open("/dev/random", O_RDONLY);
unsigned int random_read = 0;
while (dev_random && random_read < sizeof(c->tcp.hash_secret)) {
int ret = read(dev_random,
(uint8_t *)&c->tcp.hash_secret + random_read,
sizeof(c->tcp.hash_secret) - random_read);
if (ret == -1 && errno == EINTR)
continue;
if (ret <= 0)
break;
random_read += ret;
}
if (dev_random >= 0)
close(dev_random);
if (random_read < sizeof(c->tcp.hash_secret)) {
#else
if (getrandom(&c->tcp.hash_secret, sizeof(c->tcp.hash_secret),
GRND_RANDOM) < 0) {
#endif /* !HAS_GETRANDOM */
perror("TCP initial sequence getrandom");
exit(EXIT_FAILURE);
}
for (i = 0; i < ARRAY_SIZE(tcp_l2_mh); i++)
tcp_l2_mh[i] = (struct mmsghdr) { .msg_hdr.msg_iovlen = 1 };
if (c->ifi4)
tcp_sock4_iov_init(c);
if (c->ifi6)
tcp_sock6_iov_init(c);
memset(init_sock_pool4, 0xff, sizeof(init_sock_pool4));
memset(init_sock_pool6, 0xff, sizeof(init_sock_pool6));
memset(tcp_sock_init_ext, 0xff, sizeof(tcp_sock_init_ext));
memset(tcp_sock_ns, 0xff, sizeof(tcp_sock_ns));
tcp_sock_refill_init(c);
if (c->mode == MODE_PASTA) {
tcp_splice_init(c);
NS_CALL(tcp_ns_socks_init, c);
}
return 0;
}
/**
* struct tcp_port_detect_arg - Arguments for tcp_port_detect()
* @c: Execution context
* @detect_in_ns: Detect ports bound in namespace, not in init
*/
struct tcp_port_detect_arg {
struct ctx *c;
int detect_in_ns;
};
/**
* tcp_port_detect() - Detect ports bound in namespace or init
* @arg: See struct tcp_port_detect_arg
*
* Return: 0
*/
static int tcp_port_detect(void *arg)
{
struct tcp_port_detect_arg *a = (struct tcp_port_detect_arg *)arg;
if (a->detect_in_ns) {
ns_enter(a->c);
get_bound_ports(a->c, 1, IPPROTO_TCP);
} else {
get_bound_ports(a->c, 0, IPPROTO_TCP);
}
return 0;
}
/**
* struct tcp_port_rebind_arg - Arguments for tcp_port_rebind()
* @c: Execution context
* @bind_in_ns: Rebind ports in namespace, not in init
*/
struct tcp_port_rebind_arg {
struct ctx *c;
int bind_in_ns;
};
/**
* tcp_port_rebind() - Rebind ports in namespace or init
* @arg: See struct tcp_port_rebind_arg
*
* Return: 0
*/
static int tcp_port_rebind(void *arg)
{
struct tcp_port_rebind_arg *a = (struct tcp_port_rebind_arg *)arg;
unsigned port;
if (a->bind_in_ns) {
ns_enter(a->c);
for (port = 0; port < NUM_PORTS; port++) {
if (!bitmap_isset(a->c->tcp.fwd_out.map, port)) {
if (tcp_sock_ns[port][V4] >= 0) {
close(tcp_sock_ns[port][V4]);
tcp_sock_ns[port][V4] = -1;
}
if (tcp_sock_ns[port][V6] >= 0) {
close(tcp_sock_ns[port][V6]);
tcp_sock_ns[port][V6] = -1;
}
continue;
}
/* Don't loop back our own ports */
if (bitmap_isset(a->c->tcp.fwd_in.map, port))
continue;
if ((a->c->ifi4 && tcp_sock_ns[port][V4] == -1) ||
(a->c->ifi6 && tcp_sock_ns[port][V6] == -1))
tcp_ns_sock_init(a->c, port);
}
} else {
for (port = 0; port < NUM_PORTS; port++) {
if (!bitmap_isset(a->c->tcp.fwd_in.map, port)) {
if (tcp_sock_init_ext[port][V4] >= 0) {
close(tcp_sock_init_ext[port][V4]);
tcp_sock_init_ext[port][V4] = -1;
}
if (tcp_sock_init_ext[port][V6] >= 0) {
close(tcp_sock_init_ext[port][V6]);
tcp_sock_init_ext[port][V6] = -1;
}
continue;
}
/* Don't loop back our own ports */
if (bitmap_isset(a->c->tcp.fwd_out.map, port))
continue;
if ((a->c->ifi4 && tcp_sock_init_ext[port][V4] == -1) ||
(a->c->ifi6 && tcp_sock_init_ext[port][V6] == -1))
tcp_sock_init(a->c, AF_UNSPEC, NULL, NULL,
port);
}
}
return 0;
}
/**
* tcp_timer() - Periodic tasks: port detection, closed connections, pool refill
* @c: Execution context
* @ts: Unused
*/
void tcp_timer(struct ctx *c, const struct timespec *ts)
{
union tcp_conn *conn;
(void)ts;
if (c->mode == MODE_PASTA) {
struct tcp_port_detect_arg detect_arg = { c, 0 };
struct tcp_port_rebind_arg rebind_arg = { c, 0 };
if (c->tcp.fwd_out.mode == FWD_AUTO) {
detect_arg.detect_in_ns = 0;
tcp_port_detect(&detect_arg);
rebind_arg.bind_in_ns = 1;
NS_CALL(tcp_port_rebind, &rebind_arg);
}
if (c->tcp.fwd_in.mode == FWD_AUTO) {
detect_arg.detect_in_ns = 1;
NS_CALL(tcp_port_detect, &detect_arg);
rebind_arg.bind_in_ns = 0;
tcp_port_rebind(&rebind_arg);
}
}
for (conn = tc + c->tcp.conn_count - 1; conn >= tc; conn--) {
if (conn->c.spliced) {
tcp_splice_timer(c, conn);
} else {
if (conn->tap.events == CLOSED)
tcp_conn_destroy(c, conn);
}
}
tcp_sock_refill_init(c);
if (c->mode == MODE_PASTA)
tcp_splice_refill(c);
}
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