// SPDX-License-Identifier: AGPL-3.0-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 */ /** * 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 the @tc array of struct tcp_conn, 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef HAS_GETRANDOM #include #endif #include #include #include #include #include #include #include /* 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" #define TCP_FRAMES_MEM 128 #define TCP_FRAMES \ (c->mode == MODE_PASST ? TCP_FRAMES_MEM : 1) #define TCP_FILE_PRESSURE 30 /* % of c->nofile */ #define TCP_CONN_PRESSURE 30 /* % of c->tcp.conn_count */ #define TCP_HASH_BUCKET_BITS (TCP_CONN_INDEX_BITS + 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 */ uint32_t psum; uint32_t tsum; #ifdef __AVX2__ uint8_t pad[18]; #else uint8_t pad[2]; #endif uint32_t vnet_len; struct ethhdr eh; 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 uint32_t vnet_len; struct ethhdr eh; 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 50 /* ms */ #define SYN_TIMEOUT 10 /* s */ #define ACK_TIMEOUT 2 #define FIN_TIMEOUT 60 #define ACT_TIMEOUT 7200 #define TCP_SOCK_POOL_TSH 16 /* Refill in ns if > x used */ #define LOW_RTT_TABLE_SIZE 8 #define LOW_RTT_THRESHOLD 10 /* us */ /* We need to include for tcpi_bytes_acked, instead of * , 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 /** * struct tcp_conn - Descriptor for a TCP connection (not spliced) * @next_index: Connection index of next item in hash chain, -1 for none * @tap_mss: MSS advertised by tap/guest, rounded to 2 ^ TCP_MSS_BITS * @sock: Socket descriptor number * @events: Connection events, implying connection states * @timer: timerfd descriptor for timeout events * @flags: Connection flags representing internal attributes * @hash_bucket: Bucket index in connection lookup hash table * @retrans: Number of retransmissions occurred due to ACK_TIMEOUT * @ws_from_tap: Window scaling factor advertised from tap/guest * @ws_to_tap: Window scaling factor advertised to tap/guest * @sndbuf: Sending buffer in kernel, rounded to 2 ^ SNDBUF_BITS * @seq_dup_ack_approx: Last duplicate ACK number sent to tap * @a.a6: IPv6 remote address, can be IPv4-mapped * @a.a4.zero: Zero prefix for IPv4-mapped, see RFC 6890, Table 20 * @a.a4.one: Ones prefix for IPv4-mapped * @a.a4.a: IPv4 address * @tap_port: Guest-facing tap port * @sock_port: Remote, socket-facing port * @wnd_from_tap: Last window size from tap, unscaled (as received) * @wnd_to_tap: Sending window advertised to tap, unscaled (as sent) * @seq_to_tap: Next sequence for packets to tap * @seq_ack_from_tap: Last ACK number received from tap * @seq_from_tap: Next sequence for packets from tap (not actually sent) * @seq_ack_to_tap: Last ACK number sent to tap * @seq_init_from_tap: Initial sequence number from tap */ struct tcp_conn { int next_index :TCP_CONN_INDEX_BITS + 2; #define TCP_RETRANS_BITS 3 unsigned int retrans :TCP_RETRANS_BITS; #define TCP_MAX_RETRANS ((1U << TCP_RETRANS_BITS) - 1) #define TCP_WS_BITS 4 /* RFC 7323 */ #define TCP_WS_MAX 14 unsigned int ws_from_tap :TCP_WS_BITS; unsigned int ws_to_tap :TCP_WS_BITS; int sock :SOCKET_REF_BITS; uint8_t events; #define CLOSED 0 #define SOCK_ACCEPTED BIT(0) /* implies SYN sent to tap */ #define TAP_SYN_RCVD BIT(1) /* implies socket connecting */ #define TAP_SYN_ACK_SENT BIT( 3) /* implies socket connected */ #define ESTABLISHED BIT(2) #define SOCK_FIN_RCVD BIT( 3) #define SOCK_FIN_SENT BIT( 4) #define TAP_FIN_RCVD BIT( 5) #define TAP_FIN_SENT BIT( 6) #define TAP_FIN_ACKED BIT( 7) #define CONN_STATE_BITS /* Setting these clears other flags */ \ (SOCK_ACCEPTED | TAP_SYN_RCVD | ESTABLISHED) int timer :SOCKET_REF_BITS; uint8_t flags; #define STALLED BIT(0) #define LOCAL BIT(1) #define WND_CLAMPED BIT(2) #define IN_EPOLL BIT(3) #define ACTIVE_CLOSE BIT(4) #define ACK_TO_TAP_DUE BIT(5) #define ACK_FROM_TAP_DUE BIT(6) unsigned int hash_bucket :TCP_HASH_BUCKET_BITS; #define TCP_MSS_BITS 14 unsigned int tap_mss :TCP_MSS_BITS; #define MSS_SET(conn, mss) (conn->tap_mss = (mss >> (16 - TCP_MSS_BITS))) #define MSS_GET(conn) (conn->tap_mss << (16 - TCP_MSS_BITS)) #define SNDBUF_BITS 24 unsigned int sndbuf :SNDBUF_BITS; #define SNDBUF_SET(conn, bytes) (conn->sndbuf = ((bytes) >> (32 - SNDBUF_BITS))) #define SNDBUF_GET(conn) (conn->sndbuf << (32 - SNDBUF_BITS)) uint8_t seq_dup_ack_approx; union { struct in6_addr a6; struct { uint8_t zero[10]; uint8_t one[2]; struct in_addr a; } a4; } a; #define CONN_V4(conn) IN6_IS_ADDR_V4MAPPED(&conn->a.a6) #define CONN_V6(conn) (!CONN_V4(conn)) in_port_t tap_port; in_port_t sock_port; uint16_t wnd_from_tap; uint16_t wnd_to_tap; uint32_t seq_to_tap; uint32_t seq_ack_from_tap; uint32_t seq_from_tap; uint32_t seq_ack_to_tap; uint32_t seq_init_from_tap; }; #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)) #define CONN(index) (tc + (index)) /* We probably don't want to use gcc statement expressions (for portability), so * use this only after well-defined sequence points (no pre-/post-increments). */ #define CONN_OR_NULL(index) \ (((int)(index) >= 0 && (index) < TCP_MAX_CONNS) ? (tc + (index)) : NULL) 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", "IN_EPOLL", "ACTIVE_CLOSE", "ACK_TO_TAP_DUE", "ACK_FROM_TAP_DUE", }; /* Port re-mappings as delta, indexed by original destination port */ static in_port_t tcp_port_delta_to_tap [USHRT_MAX]; static in_port_t tcp_port_delta_to_init [USHRT_MAX]; /* Listening sockets, used for automatic port forwarding in pasta mode only */ static int tcp_sock_init_lo [USHRT_MAX][IP_VERSIONS]; static int tcp_sock_init_ext [USHRT_MAX][IP_VERSIONS]; static int tcp_sock_ns [USHRT_MAX][IP_VERSIONS]; /* Table of destinations with very low RTT (assumed to be local), LRU */ static struct in6_addr low_rtt_dst[LOW_RTT_TABLE_SIZE]; /* Static buffers */ /** * tcp4_l2_buf_t - Pre-cooked IPv4 packet buffers for tap connections * @psum: Partial IP header checksum (excluding tot_len and saddr) * @tsum: Partial TCP header checksum (excluding length and saddr) * @pad: Align TCP header to 32 bytes, for AVX2 checksum calculation only * @vnet_len: 4-byte qemu vnet buffer length descriptor, only for passt mode * @eh: Pre-filled Ethernet header * @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 { uint32_t psum; /* 0 */ uint32_t tsum; /* 4 */ #ifdef __AVX2__ uint8_t pad[18]; /* 8, align th to 32 bytes */ #else uint8_t pad[2]; /* align iph to 4 bytes 8 */ #endif uint32_t vnet_len; /* 26 10 */ struct ethhdr eh; /* 30 14 */ struct iphdr iph; /* 44 28 */ struct tcphdr th; /* 64 48 */ uint8_t data[MSS4]; /* 84 68 */ /* 65541 65525 */ #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; static size_t tcp4_l2_buf_bytes; /** * tcp6_l2_buf_t - Pre-cooked IPv6 packet buffers for tap connections * @pad: Align IPv6 header for checksum calculation to 32B (AVX2) or 4B * @vnet_len: 4-byte qemu vnet buffer length descriptor, only for passt mode * @eh: Pre-filled Ethernet header * @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 uint32_t vnet_len; /* 14 2 */ struct ethhdr eh; /* 18 6 */ struct ipv6hdr ip6h; /* 32 20 */ struct tcphdr th; /* 72 60 */ uint8_t data[MSS6]; /* 92 80 */ /* 65639 65627 */ #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; static size_t tcp6_l2_buf_bytes; /* 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) * @psum: Partial IP header checksum (excluding tot_len and saddr) * @tsum: Partial TCP header checksum (excluding length and saddr) * @pad: Align TCP header to 32 bytes, for AVX2 checksum calculation only * @vnet_len: 4-byte qemu vnet buffer length descriptor, only for passt mode * @eh: Pre-filled Ethernet header * @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 { uint32_t psum; /* 0 */ uint32_t tsum; /* 4 */ #ifdef __AVX2__ uint8_t pad[18]; /* 8, align th to 32 bytes */ #else uint8_t pad[2]; /* align iph to 4 bytes 8 */ #endif uint32_t vnet_len; /* 26 10 */ struct ethhdr eh; /* 30 14 */ struct iphdr iph; /* 44 28 */ struct tcphdr th; /* 64 48 */ 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; static size_t tcp4_l2_flags_buf_bytes; /** * 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 * @vnet_len: 4-byte qemu vnet buffer length descriptor, only for passt mode * @eh: Pre-filled Ethernet header * @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 uint32_t vnet_len; /* 14 2 */ struct ethhdr eh; /* 18 6 */ 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; static size_t tcp6_l2_flags_buf_bytes; /* TCP connections */ static struct tcp_conn tc[TCP_MAX_CONNS]; /* Table for lookup from remote address, local port, remote port */ static struct tcp_conn *tc_hash[TCP_HASH_TABLE_SIZE]; /* Pools for pre-opened sockets */ int init_sock_pool4 [TCP_SOCK_POOL_SIZE]; int init_sock_pool6 [TCP_SOCK_POOL_SIZE]; int ns_sock_pool4 [TCP_SOCK_POOL_SIZE]; int ns_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_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_conn *conn) { int m = (conn->flags & IN_EPOLL) ? EPOLL_CTL_MOD : EPOLL_CTL_ADD; union epoll_ref ref = { .r.proto = IPPROTO_TCP, .r.s = conn->sock, .r.p.tcp.tcp.index = conn - tc, .r.p.tcp.tcp.v6 = CONN_V6(conn) }; struct epoll_event ev = { .data.u64 = ref.u64 }; if (conn->events == CLOSED) { if (conn->flags & 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->flags |= IN_EPOLL; /* No need to log this */ if (conn->timer != -1) { union epoll_ref ref_t = { .r.proto = IPPROTO_TCP, .r.s = conn->sock, .r.p.tcp.tcp.timer = 1, .r.p.tcp.tcp.index = conn - tc }; 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_conn *conn) { struct itimerspec it = { { 0 }, { 0 } }; if (conn->events == CLOSED) return; if (conn->timer == -1) { union epoll_ref ref = { .r.proto = IPPROTO_TCP, .r.s = conn->sock, .r.p.tcp.tcp.timer = 1, .r.p.tcp.tcp.index = conn - tc }; struct epoll_event ev = { .data.u64 = ref.u64, .events = EPOLLIN | EPOLLET }; int fd; fd = timerfd_create(CLOCK_MONOTONIC, 0); if (fd == -1 || fd > SOCKET_MAX) { debug("TCP: failed to get timer: %s", strerror(errno)); 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 - tc, 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_conn *conn, unsigned long flag) { if (flag & (flag - 1)) { if (!(conn->flags & ~flag)) return; conn->flags &= flag; if (fls(~flag) >= 0) { debug("TCP: index %li: %s dropped", conn - tc, tcp_flag_str[fls(~flag)]); } } else { if (conn->flags & flag) return; conn->flags |= flag; if (fls(flag) >= 0) { debug("TCP: index %li: %s", conn - tc, tcp_flag_str[fls(flag)]); } } 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_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 - tc, 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 - tc, 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_remap_to_tap() - Set delta for port translation toward guest/tap * @port: Original destination port, host order * @delta: Delta to be added to original destination port */ void tcp_remap_to_tap(in_port_t port, in_port_t delta) { tcp_port_delta_to_tap[port] = delta; } /** * tcp_remap_to_tap() - Set delta for port translation toward init namespace * @port: Original destination port, host order * @delta: Delta to be added to original destination port */ void tcp_remap_to_init(in_port_t port, in_port_t delta) { tcp_port_delta_to_init[port] = delta; } /** * 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_conn *conn) { int i; for (i = 0; i < LOW_RTT_TABLE_SIZE; i++) if (IN6_ARE_ADDR_EQUAL(&conn->a.a6, 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_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 (IN6_ARE_ADDR_EQUAL(&conn->a.a6, 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; memcpy(low_rtt_dst + hole++, &conn->a.a6, sizeof(conn->a.a6)); if (hole == LOW_RTT_TABLE_SIZE) hole = 0; memcpy(low_rtt_dst + hole, &in6addr_any, sizeof(conn->a.a6)); #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_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 = buf->psum; sum += buf->iph.tot_len; sum += (buf->iph.saddr >> 16) & 0xffff; sum += buf->iph.saddr & 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 = buf->tsum; sum += (buf->iph.saddr >> 16) & 0xffff; sum += buf->iph.saddr & 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 * @ip_da: Pointer to IPv4 destination address, NULL if unchanged */ void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s, const uint32_t *ip_da) { 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]; if (eth_d) { memcpy(b4->eh.h_dest, eth_d, ETH_ALEN); memcpy(b6->eh.h_dest, eth_d, ETH_ALEN); memcpy(b4f->eh.h_dest, eth_d, ETH_ALEN); memcpy(b6f->eh.h_dest, eth_d, ETH_ALEN); } if (eth_s) { memcpy(b4->eh.h_source, eth_s, ETH_ALEN); memcpy(b6->eh.h_source, eth_s, ETH_ALEN); memcpy(b4f->eh.h_source, eth_s, ETH_ALEN); memcpy(b6f->eh.h_source, eth_s, ETH_ALEN); } if (ip_da) { b4f->iph.daddr = b4->iph.daddr = *ip_da; if (!i) { b4f->iph.saddr = b4->iph.saddr = 0; b4f->iph.tot_len = b4->iph.tot_len = 0; b4f->iph.check = b4->iph.check = 0; b4f->psum = b4->psum = sum_16b(&b4->iph, 20); b4->tsum = ((*ip_da >> 16) & 0xffff) + (*ip_da & 0xffff) + htons(IPPROTO_TCP); b4f->tsum = b4->tsum; } else { b4f->psum = b4->psum = tcp4_l2_buf[0].psum; b4f->tsum = b4->tsum = tcp4_l2_buf[0].tsum; } } } } /** * tcp_sock4_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets */ static void tcp_sock4_iov_init(void) { struct iovec *iov; int i; for (i = 0; i < ARRAY_SIZE(tcp4_l2_buf); i++) { tcp4_l2_buf[i] = (struct tcp4_l2_buf_t) { 0, 0, { 0 }, 0, L2_BUF_ETH_IP4_INIT, L2_BUF_IP4_INIT(IPPROTO_TCP), { .doff = sizeof(struct tcphdr) / 4, .ack = 1 }, { 0 }, }; } for (i = 0; i < ARRAY_SIZE(tcp4_l2_flags_buf); i++) { tcp4_l2_flags_buf[i] = (struct tcp4_l2_flags_buf_t) { 0, 0, { 0 }, 0, L2_BUF_ETH_IP4_INIT, L2_BUF_IP4_INIT(IPPROTO_TCP), { 0 }, { 0 }, }; } for (i = 0, iov = tcp4_l2_iov; i < TCP_FRAMES_MEM; i++, iov++) { iov->iov_base = &tcp4_l2_buf[i].vnet_len; iov->iov_len = MSS_DEFAULT; } for (i = 0, iov = tcp4_l2_flags_iov; i < TCP_FRAMES_MEM; i++, iov++) iov->iov_base = &tcp4_l2_flags_buf[i].vnet_len; } /** * tcp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets */ static void tcp_sock6_iov_init(void) { struct iovec *iov; int i; for (i = 0; i < ARRAY_SIZE(tcp6_l2_buf); i++) { tcp6_l2_buf[i] = (struct tcp6_l2_buf_t) { { 0 }, 0, L2_BUF_ETH_IP6_INIT, L2_BUF_IP6_INIT(IPPROTO_TCP), { .doff = sizeof(struct tcphdr) / 4, .ack = 1 }, { 0 }, }; } for (i = 0; i < ARRAY_SIZE(tcp6_l2_flags_buf); i++) { tcp6_l2_flags_buf[i] = (struct tcp6_l2_flags_buf_t) { { 0 }, 0, L2_BUF_ETH_IP6_INIT, L2_BUF_IP6_INIT(IPPROTO_TCP), { 0 }, { 0 }, }; } for (i = 0, iov = tcp6_l2_iov; i < TCP_FRAMES_MEM; i++, iov++) { iov->iov_base = &tcp6_l2_buf[i].vnet_len; iov->iov_len = MSS_DEFAULT; } for (i = 0, iov = tcp6_l2_flags_iov; i < TCP_FRAMES_MEM; i++, iov++) iov->iov_base = &tcp6_l2_flags_buf[i].vnet_len; } /** * 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 (!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++); 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 * @af: Address family, AF_INET or AF_INET6 * @addr: Remote address, pointer to sin_addr or sin6_addr * @tap_port: tap-facing port * @sock_port: Socket-facing port * * Return: 1 on match, 0 otherwise */ static int tcp_hash_match(const struct tcp_conn *conn, int af, const void *addr, in_port_t tap_port, in_port_t sock_port) { if (af == AF_INET && CONN_V4(conn) && !memcmp(&conn->a.a4.a, addr, sizeof(conn->a.a4.a)) && conn->tap_port == tap_port && conn->sock_port == sock_port) return 1; if (af == AF_INET6 && IN6_ARE_ADDR_EQUAL(&conn->a.a6, addr) && conn->tap_port == tap_port && conn->sock_port == sock_port) return 1; return 0; } /** * tcp_hash() - Calculate hash value for connection given address and ports * @c: Execution context * @af: Address family, AF_INET or AF_INET6 * @addr: Remote address, pointer to sin_addr or sin6_addr * @tap_port: tap-facing port * @sock_port: Socket-facing port * * Return: hash value, already modulo size of the hash table */ #if TCP_HASH_NOINLINE __attribute__((__noinline__)) /* See comment in Makefile */ #endif static unsigned int tcp_hash(const struct ctx *c, int af, const void *addr, in_port_t tap_port, in_port_t sock_port) { uint64_t b = 0; if (af == AF_INET) { struct { struct in_addr addr; in_port_t tap_port; in_port_t sock_port; } __attribute__((__packed__)) in = { *(struct in_addr *)addr, tap_port, sock_port, }; b = siphash_8b((uint8_t *)&in, c->tcp.hash_secret); } else if (af == AF_INET6) { struct { struct in6_addr addr; in_port_t tap_port; in_port_t sock_port; } __attribute__((__packed__)) in = { *(struct in6_addr *)addr, tap_port, sock_port, }; b = siphash_20b((uint8_t *)&in, c->tcp.hash_secret); } return (unsigned int)(b % TCP_HASH_TABLE_SIZE); } /** * tcp_hash_insert() - Insert connection into hash table, chain link * @c: Execution context * @conn: Connection pointer * @af: Address family, AF_INET or AF_INET6 * @addr: Remote address, pointer to sin_addr or sin6_addr */ static void tcp_hash_insert(const struct ctx *c, struct tcp_conn *conn, int af, const void *addr) { int b; b = tcp_hash(c, af, addr, conn->tap_port, conn->sock_port); conn->next_index = tc_hash[b] ? tc_hash[b] - tc : -1; tc_hash[b] = conn; conn->hash_bucket = b; debug("TCP: hash table insert: index %li, sock %i, bucket: %i, next: " "%p", conn - tc, conn->sock, b, CONN_OR_NULL(conn->next_index)); } /** * tcp_hash_remove() - Drop connection from hash table, chain unlink * @conn: Connection pointer */ static void tcp_hash_remove(const struct tcp_conn *conn) { struct tcp_conn *entry, *prev = NULL; int b = conn->hash_bucket; for (entry = tc_hash[b]; entry; prev = entry, entry = CONN_OR_NULL(entry->next_index)) { if (entry == conn) { if (prev) prev->next_index = conn->next_index; else tc_hash[b] = CONN_OR_NULL(conn->next_index); break; } } debug("TCP: hash table remove: index %li, sock %i, bucket: %i, new: %p", conn - tc, conn->sock, b, prev ? CONN_OR_NULL(prev->next_index) : tc_hash[b]); } /** * tcp_hash_update() - Update pointer for given connection * @old: Old connection pointer * @new: New connection pointer */ static void tcp_hash_update(struct tcp_conn *old, struct tcp_conn *new) { struct tcp_conn *entry, *prev = NULL; int b = old->hash_bucket; for (entry = tc_hash[b]; entry; prev = entry, entry = CONN_OR_NULL(entry->next_index)) { if (entry == old) { if (prev) prev->next_index = new - tc; 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", old - tc, new - tc, new->sock, b, old, new); } /** * tcp_hash_lookup() - Look up connection given remote address and ports * @c: Execution context * @af: Address family, AF_INET or AF_INET6 * @addr: Remote address, pointer to sin_addr or sin6_addr * @tap_port: tap-facing port * @sock_port: Socket-facing port * * Return: connection pointer, if found, -ENOENT otherwise */ static struct tcp_conn *tcp_hash_lookup(const struct ctx *c, int af, const void *addr, in_port_t tap_port, in_port_t sock_port) { int b = tcp_hash(c, af, addr, tap_port, sock_port); struct tcp_conn *conn; for (conn = tc_hash[b]; conn; conn = CONN_OR_NULL(conn->next_index)) { if (tcp_hash_match(conn, af, addr, tap_port, sock_port)) return conn; } return NULL; } /** * tcp_table_compact() - Perform compaction on connection table * @c: Execution context * @hole: Pointer to recently closed connection */ static void tcp_table_compact(struct ctx *c, struct tcp_conn *hole) { struct tcp_conn *from, *to; if ((hole - tc) == --c->tcp.conn_count) { debug("TCP: hash table compaction: maximum index was %li (%p)", hole - tc, hole); memset(hole, 0, sizeof(*hole)); return; } from = CONN(c->tcp.conn_count); memcpy(hole, from, sizeof(*hole)); to = hole; tcp_hash_update(from, to); tcp_epoll_ctl(c, to); debug("TCP: hash table compaction: old index %li, new index %li, " "sock %i, from: %p, to: %p", from - tc, to - tc, from->sock, from, to); memset(from, 0, sizeof(*from)); } /** * tcp_conn_destroy() - Close sockets, trigger hash table removal and compaction * @c: Execution context * @conn: Connection pointer */ static void tcp_conn_destroy(struct ctx *c, struct tcp_conn *conn) { close(conn->sock); if (conn->timer != -1) close(conn->timer); tcp_hash_remove(conn); tcp_table_compact(c, conn); } static void tcp_rst_do(struct ctx *c, struct tcp_conn *conn); #define tcp_rst(c, conn) \ do { \ debug("TCP: index %li, reset at %s:%i", conn - tc, \ __func__, __LINE__); \ tcp_rst_do(c, conn); \ } while (0) /** * tcp_l2_buf_write_one() - Write a single buffer to tap file descriptor * @c: Execution context * @iov: struct iovec item pointing to buffer * @ts: Current timestamp * * Return: 0 on success, negative error code on failure (tap reset possible) */ static int tcp_l2_buf_write_one(struct ctx *c, const struct iovec *iov) { if (write(c->fd_tap, (char *)iov->iov_base + 4, iov->iov_len - 4) < 0) { debug("tap write: %s", strerror(errno)); if (errno != EAGAIN && errno != EWOULDBLOCK) tap_handler(c, c->fd_tap, EPOLLERR, NULL); return -errno; } return 0; } /** * tcp_l2_buf_flush_part() - Ensure a complete last message on partial sendmsg() * @c: Execution context * @mh: Message header that was partially sent by sendmsg() * @sent: Bytes already sent */ static void tcp_l2_buf_flush_part(const struct ctx *c, const struct msghdr *mh, size_t sent) { size_t end = 0, missing; struct iovec *iov; unsigned int i; char *p; for (i = 0, iov = mh->msg_iov; i < mh->msg_iovlen; i++, iov++) { end += iov->iov_len; if (end >= sent) break; } missing = end - sent; p = (char *)iov->iov_base + iov->iov_len - missing; if (send(c->fd_tap, p, missing, MSG_NOSIGNAL)) debug("TCP: failed to flush %lu missing bytes to tap", missing); } /** * tcp_l2_flags_buf_flush() - Send out buffers for segments with or without data * @c: Execution context * @mh: Message header pointing to buffers, msg_iovlen not set * @buf_used: Pointer to count of used buffers, set to 0 on return * @buf_bytes: Pointer to count of buffer bytes, set to 0 on return */ static void tcp_l2_buf_flush(struct ctx *c, struct msghdr *mh, unsigned int *buf_used, size_t *buf_bytes) { if (!(mh->msg_iovlen = *buf_used)) return; if (c->mode == MODE_PASST) { size_t n = sendmsg(c->fd_tap, mh, MSG_NOSIGNAL | MSG_DONTWAIT); if (n > 0 && n < *buf_bytes) tcp_l2_buf_flush_part(c, mh, n); } else { size_t i; for (i = 0; i < mh->msg_iovlen; i++) { struct iovec *iov = &mh->msg_iov[i]; if (tcp_l2_buf_write_one(c, iov)) i--; } } *buf_used = *buf_bytes = 0; pcapm(mh); } /** * tcp_l2_flags_buf_flush() - Send out buffers for segments with no data (flags) * @c: Execution context */ static void tcp_l2_flags_buf_flush(struct ctx *c) { struct msghdr mh = { 0 }; unsigned int *buf_used; size_t *buf_bytes; mh.msg_iov = tcp6_l2_flags_iov; buf_used = &tcp6_l2_flags_buf_used; buf_bytes = &tcp6_l2_flags_buf_bytes; tcp_l2_buf_flush(c, &mh, buf_used, buf_bytes); mh.msg_iov = tcp4_l2_flags_iov; buf_used = &tcp4_l2_flags_buf_used; buf_bytes = &tcp4_l2_flags_buf_bytes; tcp_l2_buf_flush(c, &mh, buf_used, buf_bytes); } /** * tcp_l2_data_buf_flush() - Send out buffers for segments with data * @c: Execution context */ static void tcp_l2_data_buf_flush(struct ctx *c) { struct msghdr mh = { 0 }; unsigned int *buf_used; size_t *buf_bytes; mh.msg_iov = tcp6_l2_iov; buf_used = &tcp6_l2_buf_used; buf_bytes = &tcp6_l2_buf_bytes; tcp_l2_buf_flush(c, &mh, buf_used, buf_bytes); mh.msg_iov = tcp4_l2_iov; buf_used = &tcp4_l2_buf_used; buf_bytes = &tcp4_l2_buf_bytes; tcp_l2_buf_flush(c, &mh, buf_used, buf_bytes); } /** * tcp_defer_handler() - Handler for TCP deferred tasks * @c: Execution context */ void tcp_defer_handler(struct ctx *c) { int max_conns = c->tcp.conn_count / 100 * TCP_CONN_PRESSURE; int max_files = c->nofile / 100 * TCP_FILE_PRESSURE; struct tcp_conn *conn; tcp_l2_flags_buf_flush(c); tcp_l2_data_buf_flush(c); tcp_splice_defer_handler(c); if (c->tcp.conn_count < MIN(max_files, max_conns)) return; for (conn = CONN(c->tcp.conn_count - 1); conn >= tc; conn--) { if (conn->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: 802.3 length, host order */ static size_t tcp_l2_buf_fill_headers(const struct ctx *c, const struct tcp_conn *conn, void *p, size_t plen, const uint16_t *check, uint32_t seq) { size_t ip_len, eth_len; #define SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq) \ do { \ b->th.source = htons(conn->sock_port); \ b->th.dest = htons(conn->tap_port); \ 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 (CONN_V6(conn)) { 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->a.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; eth_len = ip_len + sizeof(struct ethhdr); if (c->mode == MODE_PASST) b->vnet_len = htonl(eth_len); } else { 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 = conn->a.a4.a.s_addr; b->iph.daddr = c->ip4.addr_seen; 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); eth_len = ip_len + sizeof(struct ethhdr); if (c->mode == MODE_PASST) b->vnet_len = htonl(eth_len); } #undef SET_TCP_HEADER_COMMON_V4_V6 return eth_len; } /** * 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_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; 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); 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_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_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); size_t optlen = 0, eth_len; int s = conn->sock; 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); eth_len = tcp_l2_buf_fill_headers(c, conn, p, optlen, NULL, conn->seq_to_tap); iov->iov_len = eth_len + sizeof(uint32_t); if (CONN_V4(conn)) tcp4_l2_flags_buf_bytes += iov->iov_len; else tcp6_l2_flags_buf_bytes += iov->iov_len; if (th->ack) 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++; tcp4_l2_flags_buf_bytes += iov->iov_len; } 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++; tcp6_l2_flags_buf_bytes += iov->iov_len; } 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_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_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_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. */ 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 * @af: Address family, AF_INET or AF_INET6 * @addr: Remote address, pointer to sin_addr or sin6_addr * @dstport: Destination port, connection-wise, network order * @srcport: Source port, connection-wise, network order * @now: Current timestamp * * Return: initial TCP sequence */ static uint32_t tcp_seq_init(const struct ctx *c, int af, const void *addr, in_port_t dstport, in_port_t srcport, const struct timespec *now) { uint32_t ns, seq = 0; if (af == AF_INET) { struct { struct in_addr src; in_port_t srcport; struct in_addr dst; in_port_t dstport; } __attribute__((__packed__)) in = { .src = *(struct in_addr *)addr, .srcport = srcport, .dst = { c->ip4.addr }, .dstport = dstport, }; seq = siphash_12b((uint8_t *)&in, c->tcp.hash_secret); } else if (af == AF_INET6) { struct { struct in6_addr src; in_port_t srcport; struct in6_addr dst; in_port_t dstport; } __attribute__((__packed__)) in = { .src = *(struct in6_addr *)addr, .srcport = srcport, .dst = c->ip6.addr, .dstport = dstport, }; seq = siphash_36b((uint8_t *)&in, c->tcp.hash_secret); } ns = now->tv_sec * 1E9; ns += now->tv_nsec >> 5; /* 32ns ticks, overflows 32 bits every 137s */ return seq + ns; } /** * tcp_conn_new_sock() - Get socket for new connection from pool or make new one * @c: Execution context * @af: Address family * * Return: socket number if available, negative code if socket creation failed */ static int tcp_conn_new_sock(const struct ctx *c, sa_family_t af) { int *p = af == AF_INET6 ? init_sock_pool6 : init_sock_pool4, i, s = -1; for (i = 0; i < TCP_SOCK_POOL_SIZE; i++, p++) { SWAP(s, *p); if (s >= 0) break; } if (s < 0) s = socket(af, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP); if (s > SOCKET_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 * @c: Execution context * @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 ctx *c, const struct tcp_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; /* Don't upset qemu */ if (c->mode == MODE_PASST) { if (CONN_V4(conn)) mss = MIN(MSS4, mss); else mss = MIN(MSS6, mss); } return MIN(mss, USHRT_MAX); } /** * tcp_conn_from_tap() - Handle connection request (SYN segment) from tap * @c: Execution context * @af: Address family, AF_INET or AF_INET6 * @addr: Remote address, pointer to sin_addr or sin6_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 *addr, const struct tcphdr *th, const char *opts, size_t optlen, const struct timespec *now) { struct sockaddr_in addr4 = { .sin_family = AF_INET, .sin_port = th->dest, .sin_addr = *(struct in_addr *)addr, }; struct sockaddr_in6 addr6 = { .sin6_family = AF_INET6, .sin6_port = th->dest, .sin6_addr = *(struct in6_addr *)addr, }; const struct sockaddr *sa; struct tcp_conn *conn; socklen_t sl; int s, mss; if (c->tcp.conn_count >= TCP_MAX_CONNS) return; if ((s = tcp_conn_new_sock(c, af)) < 0) return; if (!c->no_map_gw) { if (af == AF_INET && addr4.sin_addr.s_addr == c->ip4.gw) addr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK); if (af == AF_INET6 && IN6_ARE_ADDR_EQUAL(addr, &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->sock = s; conn->timer = -1; conn_event(c, conn, TAP_SYN_RCVD); conn->wnd_to_tap = WINDOW_DEFAULT; mss = tcp_conn_tap_mss(c, 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; if (af == AF_INET) { sa = (struct sockaddr *)&addr4; sl = sizeof(addr4); memset(&conn->a.a4.zero, 0, sizeof(conn->a.a4.zero)); memset(&conn->a.a4.one, 0xff, sizeof(conn->a.a4.one)); memcpy(&conn->a.a4.a, addr, sizeof(conn->a.a4.a)); } else { sa = (struct sockaddr *)&addr6; sl = sizeof(addr6); memcpy(&conn->a.a6, addr, sizeof(conn->a.a6)); } conn->sock_port = ntohs(th->dest); conn->tap_port = 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; conn->seq_to_tap = tcp_seq_init(c, af, addr, th->dest, th->source, now); conn->seq_ack_from_tap = conn->seq_to_tap + 1; tcp_hash_insert(c, conn, af, addr); 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 (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, update ACK sequence * @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(struct tcp_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; if (recv(conn->sock, NULL, ack_seq - conn->seq_ack_from_tap, MSG_DONTWAIT | MSG_TRUNC) < 0) return -errno; conn->seq_ack_from_tap = ack_seq; 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(struct ctx *c, struct tcp_conn *conn, ssize_t plen, int no_csum, uint32_t seq) { struct iovec *iov; size_t len; if (CONN_V4(conn)) { struct tcp4_l2_buf_t *b = &tcp4_l2_buf[tcp4_l2_buf_used]; uint16_t *check = no_csum ? &(b - 1)->iph.check : NULL; len = tcp_l2_buf_fill_headers(c, conn, b, plen, check, seq); iov = tcp4_l2_iov + tcp4_l2_buf_used++; tcp4_l2_buf_bytes += iov->iov_len = len + sizeof(b->vnet_len); 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]; len = tcp_l2_buf_fill_headers(c, conn, b, plen, NULL, seq); iov = tcp6_l2_iov + tcp6_l2_buf_used++; tcp6_l2_buf_bytes += iov->iov_len = len + sizeof(b->vnet_len); 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_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. */ recvmsg: len = recvmsg(s, &mh_sock, MSG_PEEK); if (len < 0) { if (errno == EINTR) goto recvmsg; goto err; } if (!len) goto zero_len; 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; zero_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; } /** * tcp_data_from_tap() - tap/guest data for established connection * @c: Execution context * @conn: Connection pointer * @p: Pool of TCP packets, with TCP headers * * #syscalls sendmsg */ static void tcp_data_from_tap(struct ctx *c, struct tcp_conn *conn, const struct pool *p) { 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; for (i = 0, iov_i = 0; i < (int)p->count; i++) { uint32_t seq, seq_offset, ack_seq; struct tcphdr *th; char *data; size_t off; if (!packet_get(p, i, 0, 0, &len)) { tcp_rst(c, conn); return; } th = packet_get(p, i, 0, sizeof(*th), NULL); if (!th) { tcp_rst(c, conn); return; } off = th->doff * 4UL; if (off < sizeof(*th) || off > len) { tcp_rst(c, conn); return; } if (th->rst) { conn_event(c, conn, CLOSED); return; } 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); if (ack) { if (max_ack_seq == conn->seq_to_tap) { conn_flag(c, conn, ~ACK_FROM_TAP_DUE); conn->retrans = 0; } tcp_sock_consume(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; } tcp_rst(c, conn); return; } 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; } 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); } } /** * 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_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(c, 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_IF_NEEDED); } /** * tcp_tap_handler() - Handle packets from tap and state transitions * @c: Execution context * @af: Address family, AF_INET or AF_INET6 * @addr: Destination address * @p: Pool of TCP packets, with TCP headers * @now: Current timestamp * * Return: count of consumed packets */ int tcp_tap_handler(struct ctx *c, int af, const void *addr, const struct pool *p, const struct timespec *now) { struct tcp_conn *conn; size_t optlen, len; struct tcphdr *th; int ack_due = 0; char *opts; if (!packet_get(p, 0, 0, 0, &len)) return 1; th = packet_get(p, 0, 0, sizeof(*th), NULL); if (!th) return 1; 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, 0, sizeof(*th), optlen, NULL); conn = tcp_hash_lookup(c, af, addr, htons(th->source), htons(th->dest)); /* New connection from tap */ if (!conn) { if (opts && th->syn && !th->ack) tcp_conn_from_tap(c, af, addr, th, opts, optlen, now); return 1; } trace("TCP: packet length %lu from tap for index %lu", len, conn - tc); if (th->rst) { conn_event(c, conn, CLOSED); return p->count; } if (th->ack) { conn_flag(c, conn, ~ACK_FROM_TAP_DUE); conn->retrans = 0; } 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); else tcp_rst(c, conn); return 1; } /* Establishing connection from tap */ if (conn->events & TAP_SYN_RCVD) { if (!(conn->events & TAP_SYN_ACK_SENT)) { tcp_rst(c, conn); return p->count; } 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 p->count; } if (!th->ack) { tcp_rst(c, conn); return p->count; } tcp_clamp_window(c, conn, ntohs(th->window)); tcp_data_from_sock(c, conn); if (p->count == 1) return 1; } /* Established connections not accepting data from tap */ if (conn->events & TAP_FIN_RCVD) { 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 */ tcp_data_from_tap(c, conn, p); 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 p->count; } /** * 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_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_conn_from_sock() - Handle new connection request from listening socket * @c: Execution context * @ref: epoll reference of listening socket * @now: Current timestamp */ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref, const struct timespec *now) { struct sockaddr_storage sa; struct tcp_conn *conn; socklen_t sl; int s; if (c->tcp.conn_count >= TCP_MAX_CONNS) return; sl = sizeof(sa); s = accept4(ref.r.s, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK); if (s < 0) return; conn = CONN(c->tcp.conn_count++); conn->sock = s; conn->timer = -1; conn->ws_to_tap = conn->ws_from_tap = 0; conn_event(c, conn, SOCK_ACCEPTED); if (ref.r.p.tcp.tcp.v6) { struct sockaddr_in6 sa6; memcpy(&sa6, &sa, sizeof(sa6)); if (IN6_IS_ADDR_LOOPBACK(&sa6.sin6_addr) || IN6_ARE_ADDR_EQUAL(&sa6.sin6_addr, &c->ip6.addr_seen) || IN6_ARE_ADDR_EQUAL(&sa6.sin6_addr, &c->ip6.addr)) { struct in6_addr *src; if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw)) src = &c->ip6.gw; else src = &c->ip6.addr_ll; memcpy(&sa6.sin6_addr, src, sizeof(*src)); } memcpy(&conn->a.a6, &sa6.sin6_addr, sizeof(conn->a.a6)); conn->sock_port = ntohs(sa6.sin6_port); conn->tap_port = ref.r.p.tcp.tcp.index; conn->seq_to_tap = tcp_seq_init(c, AF_INET6, &sa6.sin6_addr, conn->sock_port, conn->tap_port, now); tcp_hash_insert(c, conn, AF_INET6, &sa6.sin6_addr); } else { struct sockaddr_in sa4; in_addr_t s_addr; memcpy(&sa4, &sa, sizeof(sa4)); s_addr = ntohl(sa4.sin_addr.s_addr); memset(&conn->a.a4.zero, 0, sizeof(conn->a.a4.zero)); memset(&conn->a.a4.one, 0xff, sizeof(conn->a.a4.one)); if (s_addr >> IN_CLASSA_NSHIFT == IN_LOOPBACKNET || s_addr == INADDR_ANY || htonl(s_addr) == c->ip4.addr_seen) s_addr = ntohl(c->ip4.gw); s_addr = htonl(s_addr); memcpy(&conn->a.a4.a, &s_addr, sizeof(conn->a.a4.a)); conn->sock_port = ntohs(sa4.sin_port); conn->tap_port = ref.r.p.tcp.tcp.index; conn->seq_to_tap = tcp_seq_init(c, AF_INET, &s_addr, conn->sock_port, conn->tap_port, now); tcp_hash_insert(c, conn, AF_INET, &s_addr); } conn->seq_ack_from_tap = conn->seq_to_tap + 1; 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_timer_handler() - timerfd events: close, send ACK, retransmit, or reset * @c: Execution context * @ref: epoll reference of timer (not connection) * * #syscalls timerfd_gettime */ static void tcp_timer_handler(struct ctx *c, union epoll_ref ref) { struct tcp_conn *conn = CONN_OR_NULL(ref.r.p.tcp.tcp.index); struct itimerspec check_armed = { { 0 }, { 0 } }; if (!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); conn_flag(c, conn, ~ACK_TO_TAP_DUE); } else if (conn->flags & ACK_FROM_TAP_DUE) { if (!(conn->events & ESTABLISHED)) { debug("TCP: index %li, handshake timeout", conn - tc); tcp_rst(c, conn); } else if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED)) { debug("TCP: index %li, FIN timeout", conn - tc); tcp_rst(c, conn); } else if (conn->retrans == TCP_MAX_RETRANS) { debug("TCP: index %li, retransmissions count exceeded", conn - tc); tcp_rst(c, conn); } else { debug("TCP: index %li, ACK timeout, retry", conn - tc); 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 - tc); tcp_rst(c, conn); } } } /** * tcp_sock_handler() - Handle new data from socket, or timerfd event * @c: Execution context * @ref: epoll reference * @events: epoll events bitmap * @now: Current timestamp */ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events, const struct timespec *now) { struct tcp_conn *conn; if (ref.r.p.tcp.tcp.timer) { tcp_timer_handler(c, ref); return; } if (ref.r.p.tcp.tcp.splice) { tcp_sock_handler_splice(c, ref, events); return; } if (ref.r.p.tcp.tcp.listen) { tcp_conn_from_sock(c, ref, now); return; } if (!(conn = CONN_OR_NULL(ref.r.p.tcp.tcp.index))) return; 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_init() - Initialise listening sockets for a given port * @c: Execution context * @ns: In pasta mode, if set, bind with loopback address in namespace * @af: Address family to select a specific IP version, or AF_UNSPEC * @addr: Pointer to address for binding, NULL if not configured * @port: Port, host order */ void tcp_sock_init(const struct ctx *c, int ns, sa_family_t af, const void *addr, in_port_t port) { union tcp_epoll_ref tref = { .tcp.listen = 1 }; const void *bind_addr; int s; if (ns) { tref.tcp.index = (in_port_t)(port + tcp_port_delta_to_init[port]); } else { tref.tcp.index = (in_port_t)(port + tcp_port_delta_to_tap[port]); } if (af == AF_INET || af == AF_UNSPEC) { if (!addr && c->mode == MODE_PASTA) bind_addr = &c->ip4.addr; else bind_addr = addr; tref.tcp.v6 = 0; tref.tcp.splice = 0; if (!ns) { s = sock_l4(c, AF_INET, IPPROTO_TCP, bind_addr, port, tref.u32); if (s >= 0) tcp_sock_set_bufsize(c, s); else s = -1; if (c->tcp.init_detect_ports) tcp_sock_init_ext[port][V4] = s; } if (c->mode == MODE_PASTA) { bind_addr = &(uint32_t){ htonl(INADDR_LOOPBACK) }; tref.tcp.splice = 1; s = sock_l4(c, AF_INET, IPPROTO_TCP, bind_addr, port, tref.u32); if (s >= 0) tcp_sock_set_bufsize(c, s); else s = -1; if (c->tcp.ns_detect_ports) { if (ns) tcp_sock_ns[port][V4] = s; else tcp_sock_init_lo[port][V4] = s; } } } if (af == AF_INET6 || af == AF_UNSPEC) { if (!addr && c->mode == MODE_PASTA) bind_addr = &c->ip6.addr; else bind_addr = addr; tref.tcp.v6 = 1; tref.tcp.splice = 0; if (!ns) { s = sock_l4(c, AF_INET6, IPPROTO_TCP, bind_addr, port, tref.u32); if (s >= 0) tcp_sock_set_bufsize(c, s); else s = -1; if (c->tcp.init_detect_ports) tcp_sock_init_ext[port][V6] = s; } if (c->mode == MODE_PASTA) { bind_addr = &in6addr_loopback; tref.tcp.splice = 1; s = sock_l4(c, AF_INET6, IPPROTO_TCP, bind_addr, port, tref.u32); if (s >= 0) tcp_sock_set_bufsize(c, s); else s = -1; if (c->tcp.ns_detect_ports) { if (ns) tcp_sock_ns[port][V6] = s; else tcp_sock_init_lo[port][V6] = s; } } } } /** * tcp_sock_init_ns() - Bind sockets in namespace for inbound connections * @arg: Execution context * * Return: 0 */ static int tcp_sock_init_ns(void *arg) { struct ctx *c = (struct ctx *)arg; int port; ns_enter(c); for (port = 0; port < USHRT_MAX; port++) { if (!bitmap_isset(c->tcp.port_to_init, port)) continue; tcp_sock_init(c, 1, AF_UNSPEC, NULL, port); } return 0; } /** * struct tcp_sock_refill_arg - Arguments for tcp_sock_refill() * @c: Execution context * @ns: Set to refill pool of sockets created in namespace */ struct tcp_sock_refill_arg { struct ctx *c; int ns; }; /** * tcp_sock_refill() - Refill pool of pre-opened sockets * @arg: See @tcp_sock_refill_arg * * Return: 0 */ static int tcp_sock_refill(void *arg) { struct tcp_sock_refill_arg *a = (struct tcp_sock_refill_arg *)arg; int i, *p4, *p6; if (a->ns) { ns_enter(a->c); p4 = ns_sock_pool4; p6 = ns_sock_pool6; } else { p4 = init_sock_pool4; p6 = init_sock_pool6; } for (i = 0; a->c->ifi4 && i < TCP_SOCK_POOL_SIZE; i++, p4++) { if (*p4 >= 0) break; *p4 = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP); if (*p4 > SOCKET_MAX) { close(*p4); *p4 = -1; return -EIO; } if (*p4 >= 0) tcp_sock_set_bufsize(a->c, *p4); } for (i = 0; a->c->ifi6 && i < TCP_SOCK_POOL_SIZE; i++, p6++) { if (*p6 >= 0) break; *p6 = socket(AF_INET6, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP); if (*p6 > SOCKET_MAX) { close(*p6); *p6 = -1; return -EIO; } if (*p6 >= 0) tcp_sock_set_bufsize(a->c, *p6); } return 0; } /** * 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) { struct tcp_sock_refill_arg refill_arg = { c, 0 }; 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(); if (c->ifi6) tcp_sock6_iov_init(); memset(init_sock_pool4, 0xff, sizeof(init_sock_pool4)); memset(init_sock_pool6, 0xff, sizeof(init_sock_pool6)); memset(ns_sock_pool4, 0xff, sizeof(ns_sock_pool4)); memset(ns_sock_pool6, 0xff, sizeof(ns_sock_pool6)); memset(tcp_sock_init_lo, 0xff, sizeof(tcp_sock_init_lo)); memset(tcp_sock_init_ext, 0xff, sizeof(tcp_sock_init_ext)); memset(tcp_sock_ns, 0xff, sizeof(tcp_sock_ns)); tcp_sock_refill(&refill_arg); if (c->mode == MODE_PASTA) { tcp_splice_init(c); NS_CALL(tcp_sock_init_ns, c); refill_arg.ns = 1; NS_CALL(tcp_sock_refill, &refill_arg); tcp_splice_timer(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; int port; if (a->bind_in_ns) { ns_enter(a->c); for (port = 0; port < USHRT_MAX; port++) { if (!bitmap_isset(a->c->tcp.port_to_init, 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.port_to_tap, port)) continue; if ((a->c->ifi4 && tcp_sock_ns[port][V4] == -1) || (a->c->ifi6 && tcp_sock_ns[port][V6] == -1)) tcp_sock_init(a->c, 1, AF_UNSPEC, NULL, port); } } else { for (port = 0; port < USHRT_MAX; port++) { if (!bitmap_isset(a->c->tcp.port_to_tap, 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; } if (tcp_sock_init_lo[port][V4] >= 0) { close(tcp_sock_init_lo[port][V4]); tcp_sock_init_lo[port][V4] = -1; } if (tcp_sock_init_lo[port][V6] >= 0) { close(tcp_sock_init_lo[port][V6]); tcp_sock_init_lo[port][V6] = -1; } continue; } /* Don't loop back our own ports */ if (bitmap_isset(a->c->tcp.port_to_init, 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, 0, AF_UNSPEC, 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) { struct tcp_sock_refill_arg refill_arg = { c, 0 }; struct 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.init_detect_ports) { 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.ns_detect_ports) { 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 = CONN(c->tcp.conn_count - 1); conn >= tc; conn--) { if (conn->events == CLOSED) tcp_conn_destroy(c, conn); } tcp_sock_refill(&refill_arg); if (c->mode == MODE_PASTA) { refill_arg.ns = 1; if ((c->ifi4 && ns_sock_pool4[TCP_SOCK_POOL_TSH] < 0) || (c->ifi6 && ns_sock_pool6[TCP_SOCK_POOL_TSH] < 0)) NS_CALL(tcp_sock_refill, &refill_arg); tcp_splice_timer(c); } }