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Wed, 18 Aug 2021 15:26:17 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id HyKCF5kmHWGOfgAAGKfGzw (envelope-from ); Wed, 18 Aug 2021 15:26:17 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: a530762d-025b-4ec1-b95e-f3ff4ecab5a7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1629300377; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=Ru9tdnr7RGNWbnwLSBztvmMC/Sy6D40bdl/GXajU2l4=; b=VRuUJ7c60SuloVWkLtr1a0bk9fGtwVfU4YyohCppk1Wii0i3LWWf0gD+krLeOgXBEmJgcL lFEp96KRUGMay54R3H11Dy0EJXttmkEbTlf9f3dw7hxELhy0sQAbk9USiBAdNzpW4Gf8Lq pm4jBM18M8tUANLwQyzQ2zKx50Fb4p0= From: Juergen Gross To: minios-devel@lists.xenproject.org, xen-devel@lists.xenproject.org Cc: samuel.thibault@ens-lyon.org, wl@xen.org, Juergen Gross Subject: [PATCH] mini-os: xenbus: support large messages Date: Wed, 18 Aug 2021 17:26:10 +0200 Message-Id: <20210818152610.6114-1-jgross@suse.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) X-ZM-MESSAGEID: 1629300412812100001 Content-Type: text/plain; charset="utf-8" Today the implementation of the xenbus protocol in Mini-OS will only allow to transfer the complete message to or from the ring page buffer. This is limiting the maximum message size to lower values as the xenbus protocol normally would allow. Change that by allowing to transfer the xenbus message in chunks as soon as they are available. Avoid crashing Mini-OS in case of illegal data read from the ring buffer. Signed-off-by: Juergen Gross --- xenbus/xenbus.c | 212 ++++++++++++++++++++++++++++-------------------- 1 file changed, 124 insertions(+), 88 deletions(-) diff --git a/xenbus/xenbus.c b/xenbus/xenbus.c index 23de61e..3fbb122 100644 --- a/xenbus/xenbus.c +++ b/xenbus/xenbus.c @@ -29,6 +29,7 @@ #include #include #include +#include =20 #define min(x,y) ({ \ typeof(x) tmpx =3D (x); \ @@ -46,6 +47,7 @@ static struct xenstore_domain_interface *xenstore_buf; static DECLARE_WAIT_QUEUE_HEAD(xb_waitq); DECLARE_WAIT_QUEUE_HEAD(xenbus_watch_queue); +static __DECLARE_SEMAPHORE_GENERIC(xb_write_sem, 1); =20 xenbus_event_queue xenbus_events; static struct watch { @@ -231,75 +233,105 @@ char *xenbus_wait_for_state_change(const char* path,= XenbusState *state, xenbus_ } =20 =20 +static void xenbus_read_data(char *buf, unsigned int len) +{ + unsigned int off =3D 0; + unsigned int prod; + unsigned int size; + int notify; + + while (off !=3D len) + { + if (xenstore_buf->rsp_prod =3D=3D xenstore_buf->rsp_cons) + wait_event(xb_waitq, + xenstore_buf->rsp_prod !=3D xenstore_buf->rsp_cons); + + prod =3D xenstore_buf->rsp_prod; + DEBUG("Rsp_cons %d, rsp_prod %d.\n", xenstore_buf->rsp_cons, prod); + size =3D min(len - off, prod - xenstore_buf->rsp_cons); + memcpy_from_ring(xenstore_buf->rsp, buf + off, + MASK_XENSTORE_IDX(xenstore_buf->rsp_cons), size); + off +=3D size; + notify =3D (xenstore_buf->rsp_cons + XENSTORE_RING_SIZE =3D=3D + xenstore_buf->rsp_prod); + rmb(); + xenstore_buf->rsp_cons +=3D size; + wmb(); + if (notify) + notify_remote_via_evtchn(xenbus_evtchn); + } +} + static void xenbus_thread_func(void *ign) { struct xsd_sockmsg msg; - unsigned prod =3D xenstore_buf->rsp_prod; + char *data; =20 for (;;) { - wait_event(xb_waitq, prod !=3D xenstore_buf->rsp_prod); - while (1) { - prod =3D xenstore_buf->rsp_prod; - DEBUG("Rsp_cons %d, rsp_prod %d.\n", xenstore_buf->rsp_cons, - xenstore_buf->rsp_prod); - if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons < sizeof(m= sg)) - break; - rmb(); - memcpy_from_ring(xenstore_buf->rsp, &msg, - MASK_XENSTORE_IDX(xenstore_buf->rsp_cons), - sizeof(msg)); - DEBUG("Msg len %d, %d avail, id %d.\n", msg.len + sizeof(msg), - xenstore_buf->rsp_prod - xenstore_buf->rsp_cons, msg.req= _id); - - if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons < - sizeof(msg) + msg.len) - break; - - DEBUG("Message is good.\n"); - - if (msg.type =3D=3D XS_WATCH_EVENT) { - struct xenbus_event *event =3D malloc(sizeof(*event) + msg= .len); - xenbus_event_queue *events =3D NULL; - char *data =3D (char*)event + sizeof(*event); - struct watch *watch; - - memcpy_from_ring(xenstore_buf->rsp, data, - MASK_XENSTORE_IDX(xenstore_buf->rsp_cons + sizeof(msg)= ), - msg.len); - - event->path =3D data; - event->token =3D event->path + strlen(event->path) + 1; - - mb(); - xenstore_buf->rsp_cons +=3D msg.len + sizeof(msg); - - for (watch =3D watches; watch; watch =3D watch->next) - if (!strcmp(watch->token, event->token)) { - events =3D watch->events; - break; - } - - if (events) { - event->next =3D *events; - *events =3D event; - wake_up(&xenbus_watch_queue); - } else { - printk("unexpected watch token %s\n", event->token); - free(event); + xenbus_read_data((char *)&msg, sizeof(msg)); + DEBUG("Msg len %d, %d avail, id %d.\n", msg.len + sizeof(msg), + xenstore_buf->rsp_prod - xenstore_buf->rsp_cons, msg.req_id); + + if (msg.len > XENSTORE_PAYLOAD_MAX) { + printk("Xenstore violates protocol, message longer than allowe= d.\n"); + return; + } + + if (msg.type =3D=3D XS_WATCH_EVENT) { + struct xenbus_event *event =3D malloc(sizeof(*event) + msg.len= ); + xenbus_event_queue *events =3D NULL; + struct watch *watch; + char *c; + int zeroes =3D 0; + + data =3D (char*)event + sizeof(*event); + xenbus_read_data(data, msg.len); + + for (c =3D data; c < data + msg.len; c++) + if (!*c) + zeroes++; + if (zeroes !=3D 2) { + printk("Xenstore: illegal watch event data\n"); + free(event); + continue; + } + + event->path =3D data; + event->token =3D event->path + strlen(event->path) + 1; + + for (watch =3D watches; watch; watch =3D watch->next) + if (!strcmp(watch->token, event->token)) { + events =3D watch->events; + break; } + + if (events) { + event->next =3D *events; + *events =3D event; + wake_up(&xenbus_watch_queue); } else { - req_info[msg.req_id].reply =3D malloc(sizeof(msg) + msg.le= n); - memcpy_from_ring(xenstore_buf->rsp, req_info[msg.req_id].r= eply, - MASK_XENSTORE_IDX(xenstore_buf->rsp_cons), - msg.len + sizeof(msg)); - mb(); - xenstore_buf->rsp_cons +=3D msg.len + sizeof(msg); - wake_up(&req_info[msg.req_id].waitq); + printk("Xenstore: unexpected watch token %s\n", event->tok= en); + free(event); } =20 - wmb(); - notify_remote_via_evtchn(xenbus_evtchn); + continue; } + + data =3D malloc(sizeof(msg) + msg.len); + memcpy(data, &msg, sizeof(msg)); + xenbus_read_data(data + sizeof(msg), msg.len); + + if (msg.req_id >=3D NR_REQS || !req_info[msg.req_id].in_use) { + printk("Xenstore: illegal request id %d\n", msg.req_id); + free(data); + continue; + } + + DEBUG("Message is good.\n"); + + req_info[msg.req_id].reply =3D data; + + wake_up(&req_info[msg.req_id].waitq); } } =20 @@ -451,36 +483,40 @@ static void xb_write(int type, int req_id, xenbus_tra= nsaction_t trans_id, =20 cur_req =3D &header_req; =20 - BUG_ON(len > XENSTORE_RING_SIZE); - /* Wait for the ring to drain to the point where we can send the - message. */ - prod =3D xenstore_buf->req_prod; - if (prod + len - xenstore_buf->req_cons > XENSTORE_RING_SIZE)=20 - { - /* Wait for there to be space on the ring */ - DEBUG("prod %d, len %d, cons %d, size %d; waiting.\n", - prod, len, xenstore_buf->req_cons, XENSTORE_RING_SIZE); - wait_event(xb_waitq, - xenstore_buf->req_prod + len - xenstore_buf->req_cons <=3D - XENSTORE_RING_SIZE); - DEBUG("Back from wait.\n"); - prod =3D xenstore_buf->req_prod; - } + BUG_ON(len > XENSTORE_PAYLOAD_MAX); =20 - /* We're now guaranteed to be able to send the message without - overflowing the ring. Do so. */ + /* Make sure we are the only thread trying to write. */ + down(&xb_write_sem); + + /* Send the message in chunks using free ring space when available. */ total_off =3D 0; req_off =3D 0; - while (total_off < len)=20 + while (total_off < len) { + prod =3D xenstore_buf->req_prod; + if (prod - xenstore_buf->req_cons >=3D XENSTORE_RING_SIZE) + { + /* Send evtchn to notify remote */ + notify_remote_via_evtchn(xenbus_evtchn); + + /* Wait for there to be space on the ring */ + DEBUG("prod %d, len %d, cons %d, size %d; waiting.\n", prod, + len - total_off, xenstore_buf->req_cons, XENSTORE_RING_S= IZE); + wait_event(xb_waitq, + prod - xenstore_buf->req_cons < XENSTORE_RING_SIZE); + DEBUG("Back from wait.\n"); + } + this_chunk =3D min(cur_req->len - req_off, - XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod)); + XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod)); + this_chunk =3D min(this_chunk, + xenstore_buf->req_cons + XENSTORE_RING_SIZE - pro= d); memcpy((char *)xenstore_buf->req + MASK_XENSTORE_IDX(prod), - (char *)cur_req->data + req_off, this_chunk); + (char *)cur_req->data + req_off, this_chunk); prod +=3D this_chunk; req_off +=3D this_chunk; total_off +=3D this_chunk; - if (req_off =3D=3D cur_req->len)=20 + if (req_off =3D=3D cur_req->len) { req_off =3D 0; if (cur_req =3D=3D &header_req) @@ -488,20 +524,20 @@ static void xb_write(int type, int req_id, xenbus_tra= nsaction_t trans_id, else cur_req++; } + + /* Remote must see entire message before updating indexes */ + wmb(); + xenstore_buf->req_prod =3D prod; } =20 + /* Send evtchn to notify remote */ + notify_remote_via_evtchn(xenbus_evtchn); + DEBUG("Complete main loop of xb_write.\n"); BUG_ON(req_off !=3D 0); BUG_ON(total_off !=3D len); - BUG_ON(prod > xenstore_buf->req_cons + XENSTORE_RING_SIZE); - - /* Remote must see entire message before updating indexes */ - wmb(); - - xenstore_buf->req_prod +=3D len; =20 - /* Send evtchn to notify remote */ - notify_remote_via_evtchn(xenbus_evtchn); + up(&xb_write_sem); } =20 /* Send a mesasge to xenbus, in the same fashion as xb_write, and --=20 2.26.2