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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1775538518; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bSYhPjyMUCbINJQbYKmJPxVIaDBsqWDh+L4xXLOW1QQ=; b=D2wyNQjM/4xTm+h2D/OYZnLnTP25I6s/9oasKSK0l8OxQgVQrxJAbqm23Sa+KtM0e3757E og04+ETToayrMCBaxgENEZmI6Uf97uYuZMCHAHoK15h+i/S2XvVMpFyxlAbMLY0O3m/1K0 rHYVTpds7q/VcLWwlkM4W/9Q5XyD84Q= X-MC-Unique: Xke8I1JmOIud50myCEc5-g-1 X-Mimecast-MFC-AGG-ID: Xke8I1JmOIud50myCEc5-g_1775538514 From: Cindy Lu To: lulu@redhat.com, mst@redhat.com, jasowang@redhat.com, zhangckid@gmail.com, lizhijian@fujitsu.com, jmarcin@redhat.com, qemu-devel@nongnu.org Subject: [RFC v4 2/5] chardev/socket: add AF_PACKET initialization Date: Tue, 7 Apr 2026 13:05:49 +0800 Message-ID: <20260407050818.2249570-3-lulu@redhat.com> In-Reply-To: <20260407050818.2249570-1-lulu@redhat.com> References: <20260407050818.2249570-1-lulu@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" Teach socket chardevs to recognize AF_PACKET fds and record the state needed by later TX/RX support. Add af-packet-mode=3Dcapture|inject to QAPI and command-line parsing, reject it for non-fd address types, and validate after a client fd is attached that the supplied fd really is AF_PACKET. The socket chardev now tracks whether the underlying socket is AF_PACKET, owns separate send/receive staging buffers, and resets that state on connection teardown and reconnect. The follow-up TX and RX commits use this setup to translate between the redirector's existing length-prefixed chardev framing and raw L2 packets. Signed-off-by: Cindy Lu --- chardev/char-socket.c | 104 +++++++++++++++++++++++++++++++++- chardev/char.c | 3 + include/chardev/char-socket.h | 13 +++++ qapi/char.json | 23 +++++++- qemu-options.hx | 5 +- 5 files changed, 145 insertions(+), 3 deletions(-) diff --git a/chardev/char-socket.c b/chardev/char-socket.c index 62852e3caf..c710fdb497 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -23,6 +23,9 @@ */ =20 #include "qemu/osdep.h" +#ifdef CONFIG_LINUX +#include +#endif #include "chardev/char.h" #include "io/channel-socket.h" #include "io/channel-websock.h" @@ -32,6 +35,7 @@ #include "qapi/error.h" #include "qapi/clone-visitor.h" #include "qapi/qapi-visit-sockets.h" +#include "qapi/util.h" #include "qemu/yank.h" #include "trace.h" =20 @@ -326,6 +330,28 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, s= ize_t len) return ret; } =20 +static bool tcp_chr_is_af_packet(SocketChardev *s) +{ +#ifdef CONFIG_LINUX + return s->sioc && s->sioc->localAddr.ss_family =3D=3D AF_PACKET; +#else + return false; +#endif +} + +static void tcp_chr_reset_af_packet_buf(SocketChardev *s) +{ + s->af_packet_buf_len =3D 0; + s->af_packet_buf_offset =3D 0; +} + +static void tcp_chr_reset_af_packet_send(SocketChardev *s) +{ + s->af_packet_send_len =3D 0; + s->af_packet_send_offset =3D 0; + s->af_packet_send_len_bytes =3D 0; +} + static GSource *tcp_chr_add_watch(Chardev *chr, GIOCondition cond) { SocketChardev *s =3D SOCKET_CHARDEV(chr); @@ -384,6 +410,15 @@ static void tcp_chr_free_connection(Chardev *chr) s->sioc =3D NULL; object_unref(OBJECT(s->ioc)); s->ioc =3D NULL; + g_free(s->af_packet_buf); + s->af_packet_buf =3D NULL; + s->af_packet_buf_size =3D 0; + tcp_chr_reset_af_packet_buf(s); + g_free(s->af_packet_send_buf); + s->af_packet_send_buf =3D NULL; + s->af_packet_send_buf_size =3D 0; + tcp_chr_reset_af_packet_send(s); + s->is_af_packet =3D false; g_free(chr->filename); chr->filename =3D NULL; tcp_chr_change_state(s, TCP_CHARDEV_STATE_DISCONNECTED); @@ -889,6 +924,26 @@ static void tcp_chr_set_client_ioc_name(Chardev *chr, =20 } =20 +static bool tcp_chr_validate_af_packet_mode_fd(Chardev *chr, + QIOChannelSocket *sioc, + Error **errp) +{ + SocketChardev *s =3D SOCKET_CHARDEV(chr); + + if (!s->af_packet_mode_set) { + return true; + } + +#ifdef CONFIG_LINUX + if (sioc->localAddr.ss_family =3D=3D AF_PACKET) { + return true; + } +#endif + + error_setg(errp, "'af-packet-mode' requires an AF_PACKET fd"); + return false; +} + static int tcp_chr_new_client(Chardev *chr, QIOChannelSocket *sioc) { SocketChardev *s =3D SOCKET_CHARDEV(chr); @@ -907,6 +962,9 @@ static int tcp_chr_new_client(Chardev *chr, QIOChannelS= ocket *sioc) object_ref(OBJECT(sioc)); s->sioc =3D sioc; object_ref(OBJECT(sioc)); + s->is_af_packet =3D tcp_chr_is_af_packet(s); + tcp_chr_reset_af_packet_buf(s); + tcp_chr_reset_af_packet_send(s); =20 if (s->do_nodelay) { qio_channel_set_delay(s->ioc, false); @@ -951,6 +1009,11 @@ static int tcp_chr_add_client(Chardev *chr, int fd) char_socket_yank_iochannel, QIO_CHANNEL(sioc)); } + if (!tcp_chr_validate_af_packet_mode_fd(chr, sioc, NULL)) { + tcp_chr_change_state(s, TCP_CHARDEV_STATE_DISCONNECTED); + object_unref(OBJECT(sioc)); + return -1; + } ret =3D tcp_chr_new_client(chr, sioc); object_unref(OBJECT(sioc)); return ret; @@ -990,7 +1053,17 @@ static int tcp_chr_connect_client_sync(Chardev *chr, = Error **errp) char_socket_yank_iochannel, QIO_CHANNEL(sioc)); } - tcp_chr_new_client(chr, sioc); + if (!tcp_chr_validate_af_packet_mode_fd(chr, sioc, errp)) { + tcp_chr_change_state(s, TCP_CHARDEV_STATE_DISCONNECTED); + object_unref(OBJECT(sioc)); + return -1; + } + if (tcp_chr_new_client(chr, sioc) < 0) { + tcp_chr_change_state(s, TCP_CHARDEV_STATE_DISCONNECTED); + object_unref(OBJECT(sioc)); + error_setg(errp, "failed to initialize socket chardev client"); + return -1; + } object_unref(OBJECT(sioc)); return 0; } @@ -1312,6 +1385,11 @@ static bool qmp_chardev_validate_socket(ChardevSocke= t *sock, break; =20 case SOCKET_ADDRESS_TYPE_UNIX: + if (sock->has_af_packet_mode) { + error_setg(errp, + "'af-packet-mode' option requires 'fd' address type= "); + return false; + } if (sock->tls_creds) { error_setg(errp, "'tls_creds' option is incompatible with " @@ -1321,9 +1399,19 @@ static bool qmp_chardev_validate_socket(ChardevSocke= t *sock, break; =20 case SOCKET_ADDRESS_TYPE_INET: + if (sock->has_af_packet_mode) { + error_setg(errp, + "'af-packet-mode' option requires 'fd' address type= "); + return false; + } break; =20 case SOCKET_ADDRESS_TYPE_VSOCK: + if (sock->has_af_packet_mode) { + error_setg(errp, + "'af-packet-mode' option requires 'fd' address type= "); + return false; + } if (sock->tls_creds) { error_setg(errp, "'tls_creds' option is incompatible with " @@ -1386,6 +1474,10 @@ static void qmp_chardev_open_socket(Chardev *chr, s->is_tn3270 =3D is_tn3270; s->is_websock =3D is_websock; s->do_nodelay =3D do_nodelay; + s->af_packet_mode_set =3D sock->has_af_packet_mode; + if (sock->has_af_packet_mode) { + s->af_packet_mode =3D sock->af_packet_mode; + } if (sock->tls_creds) { Object *creds; creds =3D object_resolve_path_component( @@ -1463,6 +1555,7 @@ static void qemu_chr_parse_socket(QemuOpts *opts, Cha= rdevBackend *backend, const char *host =3D qemu_opt_get(opts, "host"); const char *port =3D qemu_opt_get(opts, "port"); const char *fd =3D qemu_opt_get(opts, "fd"); + const char *af_packet_mode =3D qemu_opt_get(opts, "af-packet-mode"); #ifdef CONFIG_LINUX bool tight =3D qemu_opt_get_bool(opts, "tight", true); bool abstract =3D qemu_opt_get_bool(opts, "abstract", false); @@ -1516,6 +1609,15 @@ static void qemu_chr_parse_socket(QemuOpts *opts, Ch= ardevBackend *backend, sock->wait =3D qemu_opt_get_bool(opts, "wait", true); sock->has_reconnect_ms =3D qemu_opt_find(opts, "reconnect-ms"); sock->reconnect_ms =3D qemu_opt_get_number(opts, "reconnect-ms", 0); + if (af_packet_mode) { + sock->af_packet_mode =3D + qapi_enum_parse(&ChardevSocketAfPacketMode_lookup, + af_packet_mode, -1, errp); + if (*errp) { + return; + } + sock->has_af_packet_mode =3D true; + } =20 sock->tls_creds =3D g_strdup(qemu_opt_get(opts, "tls-creds")); sock->tls_authz =3D g_strdup(qemu_opt_get(opts, "tls-authz")); diff --git a/chardev/char.c b/chardev/char.c index 3e432195a5..39bb0d5b68 100644 --- a/chardev/char.c +++ b/chardev/char.c @@ -910,6 +910,9 @@ QemuOptsList qemu_chardev_opts =3D { },{ .name =3D "websocket", .type =3D QEMU_OPT_BOOL, + },{ + .name =3D "af-packet-mode", + .type =3D QEMU_OPT_STRING, },{ .name =3D "width", .type =3D QEMU_OPT_NUMBER, diff --git a/include/chardev/char-socket.h b/include/chardev/char-socket.h index d6d13ad37f..8af8af6cf8 100644 --- a/include/chardev/char-socket.h +++ b/include/chardev/char-socket.h @@ -63,6 +63,19 @@ struct SocketChardev { int *write_msgfds; size_t write_msgfds_num; bool registered_yank; + bool is_af_packet; + bool af_packet_mode_set; + ChardevSocketAfPacketMode af_packet_mode; + uint8_t *af_packet_buf; + size_t af_packet_buf_size; + size_t af_packet_buf_len; + size_t af_packet_buf_offset; + uint8_t *af_packet_send_buf; + size_t af_packet_send_buf_size; + size_t af_packet_send_len; + size_t af_packet_send_offset; + uint8_t af_packet_send_len_buf[sizeof(uint32_t)]; + size_t af_packet_send_len_bytes; =20 SocketAddress *addr; bool is_listen; diff --git a/qapi/char.json b/qapi/char.json index 140614f82c..61a785727d 100644 --- a/qapi/char.json +++ b/qapi/char.json @@ -237,6 +237,22 @@ 'data': { 'device': 'str' }, 'base': 'ChardevCommon' } =20 +## +# @ChardevSocketAfPacketMode: +# +# AF_PACKET fd mode for socket chardevs. +# +# @capture: use recvfrom() to capture raw L2 frames and forward them +# through the existing chardev packet framing +# +# @inject: use sendmsg() to inject framed chardev packets back as raw +# L2 frames +# +# Since: 10.1 +## +{ 'enum': 'ChardevSocketAfPacketMode', + 'data': [ 'capture', 'inject' ] } + ## # @ChardevSocket: # @@ -274,6 +290,10 @@ # Setting this to zero disables this function. # (default: 0) (Since: 9.2) # +# @af-packet-mode: when @addr is an fd that refers to an AF_PACKET +# socket, use raw packet capture or inject instead of stream +# socket I/O (Since: 10.1) +# # Since: 1.4 ## { 'struct': 'ChardevSocket', @@ -286,7 +306,8 @@ '*telnet': 'bool', '*tn3270': 'bool', '*websocket': 'bool', - '*reconnect-ms': 'int' }, + '*reconnect-ms': 'int', + '*af-packet-mode': 'ChardevSocketAfPacketMode' }, 'base': 'ChardevCommon' } =20 ## diff --git a/qemu-options.hx b/qemu-options.hx index fca2b7bc74..0e3ce7f493 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4062,7 +4062,7 @@ The available backends are: A void device. This device will not emit any data, and will drop any data it receives. The null backend does not take any options. =20 -``-chardev socket,id=3Did[,TCP options or unix options][,server=3Don|off][= ,wait=3Don|off][,telnet=3Don|off][,websocket=3Don|off][,reconnect-ms=3Dmill= iseconds][,tls-creds=3Did][,tls-authz=3Did]`` +``-chardev socket,id=3Did[,TCP options or unix options][,server=3Don|off][= ,wait=3Don|off][,telnet=3Don|off][,websocket=3Don|off][,reconnect-ms=3Dmill= iseconds][,tls-creds=3Did][,tls-authz=3Did][,af-packet-mode=3Dcapture|injec= t]`` Create a two-way stream socket, which can be either a TCP or a unix socket. A unix socket will be created if ``path`` is specified. Behaviour is undefined if TCP options are specified for a unix @@ -4095,6 +4095,9 @@ The available backends are: deleted and recreated on the fly while the chardev server is active. If missing, it will default to denying access. =20 + ``af-packet-mode=3Dcapture|inject`` is only valid with ``fd=3D...`` wh= en + the provided file descriptor is an AF_PACKET socket. + TCP and unix socket options are given below: =20 ``TCP options: port=3Dport[,host=3Dhost][,to=3Dto][,ipv4=3Don|off][,ip= v6=3Don|off][,nodelay=3Don|off]`` --=20 2.52.0