/* * virtio-fs glue for FUSE * Copyright (C) 2018 Red Hat, Inc. and/or its affiliates * * Authors: * Dave Gilbert * * Implements the glue between libfuse and libvhost-user * * This program can be distributed under the terms of the GNU LGPLv2. * See the file COPYING.LIB */ #include "qemu/osdep.h" #include "qemu/iov.h" #include "fuse_virtio.h" #include "fuse_i.h" #include "standard-headers/linux/fuse.h" #include "fuse_misc.h" #include "fuse_opt.h" #include #include #include #include #include #include #include #include #include #include #include #include "contrib/libvhost-user/libvhost-user.h" struct fv_VuDev; struct fv_QueueInfo { pthread_t thread; struct fv_VuDev *virtio_dev; /* Our queue index, corresponds to array position */ int qidx; int kick_fd; /* The element for the command currently being processed */ VuVirtqElement *qe; bool reply_sent; }; /* * We pass the dev element into libvhost-user * and then use it to get back to the outer * container for other data. */ struct fv_VuDev { VuDev dev; struct fuse_session *se; /* * The following pair of fields are only accessed in the main * virtio_loop */ size_t nqueues; struct fv_QueueInfo **qi; }; /* From spec */ struct virtio_fs_config { char tag[36]; uint32_t num_queues; }; /* Callback from libvhost-user */ static uint64_t fv_get_features(VuDev *dev) { return 1ULL << VIRTIO_F_VERSION_1; } /* Callback from libvhost-user */ static void fv_set_features(VuDev *dev, uint64_t features) { } /* * Callback from libvhost-user if there's a new fd we're supposed to listen * to, typically a queue kick? */ static void fv_set_watch(VuDev *dev, int fd, int condition, vu_watch_cb cb, void *data) { fuse_log(FUSE_LOG_WARNING, "%s: TODO! fd=%d\n", __func__, fd); } /* * Callback from libvhost-user if we're no longer supposed to listen on an fd */ static void fv_remove_watch(VuDev *dev, int fd) { fuse_log(FUSE_LOG_WARNING, "%s: TODO! fd=%d\n", __func__, fd); } /* Callback from libvhost-user to panic */ static void fv_panic(VuDev *dev, const char *err) { fuse_log(FUSE_LOG_ERR, "%s: libvhost-user: %s\n", __func__, err); /* TODO: Allow reconnects?? */ exit(EXIT_FAILURE); } /* * Copy from an iovec into a fuse_buf (memory only) * Caller must ensure there is space */ static void copy_from_iov(struct fuse_buf *buf, size_t out_num, const struct iovec *out_sg) { void *dest = buf->mem; while (out_num) { size_t onelen = out_sg->iov_len; memcpy(dest, out_sg->iov_base, onelen); dest += onelen; out_sg++; out_num--; } } /* * Copy from one iov to another, the given number of bytes * The caller must have checked sizes. */ static void copy_iov(struct iovec *src_iov, int src_count, struct iovec *dst_iov, int dst_count, size_t to_copy) { size_t dst_offset = 0; /* Outer loop copies 'src' elements */ while (to_copy) { assert(src_count); size_t src_len = src_iov[0].iov_len; size_t src_offset = 0; if (src_len > to_copy) { src_len = to_copy; } /* Inner loop copies contents of one 'src' to maybe multiple dst. */ while (src_len) { assert(dst_count); size_t dst_len = dst_iov[0].iov_len - dst_offset; if (dst_len > src_len) { dst_len = src_len; } memcpy(dst_iov[0].iov_base + dst_offset, src_iov[0].iov_base + src_offset, dst_len); src_len -= dst_len; to_copy -= dst_len; src_offset += dst_len; dst_offset += dst_len; assert(dst_offset <= dst_iov[0].iov_len); if (dst_offset == dst_iov[0].iov_len) { dst_offset = 0; dst_iov++; dst_count--; } } src_iov++; src_count--; } } /* * Called back by ll whenever it wants to send a reply/message back * The 1st element of the iov starts with the fuse_out_header * 'unique'==0 means it's a notify message. */ int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch, struct iovec *iov, int count) { VuVirtqElement *elem; VuVirtq *q; int ret = 0; assert(count >= 1); assert(iov[0].iov_len >= sizeof(struct fuse_out_header)); struct fuse_out_header *out = iov[0].iov_base; /* TODO: Endianness! */ size_t tosend_len = iov_size(iov, count); /* unique == 0 is notification, which we don't support */ assert(out->unique); /* For virtio we always have ch */ assert(ch); assert(!ch->qi->reply_sent); elem = ch->qi->qe; q = &ch->qi->virtio_dev->dev.vq[ch->qi->qidx]; /* The 'in' part of the elem is to qemu */ unsigned int in_num = elem->in_num; struct iovec *in_sg = elem->in_sg; size_t in_len = iov_size(in_sg, in_num); fuse_log(FUSE_LOG_DEBUG, "%s: elem %d: with %d in desc of length %zd\n", __func__, elem->index, in_num, in_len); /* * The elem should have room for a 'fuse_out_header' (out from fuse) * plus the data based on the len in the header. */ if (in_len < sizeof(struct fuse_out_header)) { fuse_log(FUSE_LOG_ERR, "%s: elem %d too short for out_header\n", __func__, elem->index); ret = -E2BIG; goto err; } if (in_len < tosend_len) { fuse_log(FUSE_LOG_ERR, "%s: elem %d too small for data len %zd\n", __func__, elem->index, tosend_len); ret = -E2BIG; goto err; } copy_iov(iov, count, in_sg, in_num, tosend_len); vu_queue_push(&se->virtio_dev->dev, q, elem, tosend_len); vu_queue_notify(&se->virtio_dev->dev, q); ch->qi->reply_sent = true; err: return ret; } /* * Callback from fuse_send_data_iov_* when it's virtio and the buffer * is a single FD with FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK * We need send the iov and then the buffer. * Return 0 on success */ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch, struct iovec *iov, int count, struct fuse_bufvec *buf, size_t len) { int ret = 0; VuVirtqElement *elem; VuVirtq *q; assert(count >= 1); assert(iov[0].iov_len >= sizeof(struct fuse_out_header)); struct fuse_out_header *out = iov[0].iov_base; /* TODO: Endianness! */ size_t iov_len = iov_size(iov, count); size_t tosend_len = iov_len + len; out->len = tosend_len; fuse_log(FUSE_LOG_DEBUG, "%s: count=%d len=%zd iov_len=%zd\n", __func__, count, len, iov_len); /* unique == 0 is notification which we don't support */ assert(out->unique); /* For virtio we always have ch */ assert(ch); assert(!ch->qi->reply_sent); elem = ch->qi->qe; q = &ch->qi->virtio_dev->dev.vq[ch->qi->qidx]; /* The 'in' part of the elem is to qemu */ unsigned int in_num = elem->in_num; struct iovec *in_sg = elem->in_sg; size_t in_len = iov_size(in_sg, in_num); fuse_log(FUSE_LOG_DEBUG, "%s: elem %d: with %d in desc of length %zd\n", __func__, elem->index, in_num, in_len); /* * The elem should have room for a 'fuse_out_header' (out from fuse) * plus the data based on the len in the header. */ if (in_len < sizeof(struct fuse_out_header)) { fuse_log(FUSE_LOG_ERR, "%s: elem %d too short for out_header\n", __func__, elem->index); ret = E2BIG; goto err; } if (in_len < tosend_len) { fuse_log(FUSE_LOG_ERR, "%s: elem %d too small for data len %zd\n", __func__, elem->index, tosend_len); ret = E2BIG; goto err; } /* TODO: Limit to 'len' */ /* First copy the header data from iov->in_sg */ copy_iov(iov, count, in_sg, in_num, iov_len); /* * Build a copy of the the in_sg iov so we can skip bits in it, * including changing the offsets */ struct iovec *in_sg_cpy = calloc(sizeof(struct iovec), in_num); assert(in_sg_cpy); memcpy(in_sg_cpy, in_sg, sizeof(struct iovec) * in_num); /* These get updated as we skip */ struct iovec *in_sg_ptr = in_sg_cpy; int in_sg_cpy_count = in_num; /* skip over parts of in_sg that contained the header iov */ size_t skip_size = iov_len; size_t in_sg_left = 0; do { while (skip_size != 0 && in_sg_cpy_count) { if (skip_size >= in_sg_ptr[0].iov_len) { skip_size -= in_sg_ptr[0].iov_len; in_sg_ptr++; in_sg_cpy_count--; } else { in_sg_ptr[0].iov_len -= skip_size; in_sg_ptr[0].iov_base += skip_size; break; } } int i; for (i = 0, in_sg_left = 0; i < in_sg_cpy_count; i++) { in_sg_left += in_sg_ptr[i].iov_len; } fuse_log(FUSE_LOG_DEBUG, "%s: after skip skip_size=%zd in_sg_cpy_count=%d " "in_sg_left=%zd\n", __func__, skip_size, in_sg_cpy_count, in_sg_left); ret = preadv(buf->buf[0].fd, in_sg_ptr, in_sg_cpy_count, buf->buf[0].pos); if (ret == -1) { ret = errno; fuse_log(FUSE_LOG_DEBUG, "%s: preadv failed (%m) len=%zd\n", __func__, len); free(in_sg_cpy); goto err; } fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__, ret, len); if (ret < len && ret) { fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__); /* Skip over this much next time around */ skip_size = ret; buf->buf[0].pos += ret; len -= ret; /* Lets do another read */ continue; } if (!ret) { /* EOF case? */ fuse_log(FUSE_LOG_DEBUG, "%s: !ret in_sg_left=%zd\n", __func__, in_sg_left); break; } if (ret != len) { fuse_log(FUSE_LOG_DEBUG, "%s: ret!=len\n", __func__); ret = EIO; free(in_sg_cpy); goto err; } in_sg_left -= ret; len -= ret; } while (in_sg_left); free(in_sg_cpy); /* Need to fix out->len on EOF */ if (len) { struct fuse_out_header *out_sg = in_sg[0].iov_base; tosend_len -= len; out_sg->len = tosend_len; } ret = 0; vu_queue_push(&se->virtio_dev->dev, q, elem, tosend_len); vu_queue_notify(&se->virtio_dev->dev, q); err: if (ret == 0) { ch->qi->reply_sent = true; } return ret; } /* Thread function for individual queues, created when a queue is 'started' */ static void *fv_queue_thread(void *opaque) { struct fv_QueueInfo *qi = opaque; struct VuDev *dev = &qi->virtio_dev->dev; struct VuVirtq *q = vu_get_queue(dev, qi->qidx); struct fuse_session *se = qi->virtio_dev->se; struct fuse_chan ch; struct fuse_buf fbuf; fbuf.mem = NULL; fbuf.flags = 0; fuse_mutex_init(&ch.lock); ch.fd = (int)0xdaff0d111; ch.qi = qi; fuse_log(FUSE_LOG_INFO, "%s: Start for queue %d kick_fd %d\n", __func__, qi->qidx, qi->kick_fd); while (1) { struct pollfd pf[1]; pf[0].fd = qi->kick_fd; pf[0].events = POLLIN; pf[0].revents = 0; fuse_log(FUSE_LOG_DEBUG, "%s: Waiting for Queue %d event\n", __func__, qi->qidx); int poll_res = ppoll(pf, 1, NULL, NULL); if (poll_res == -1) { if (errno == EINTR) { fuse_log(FUSE_LOG_INFO, "%s: ppoll interrupted, going around\n", __func__); continue; } fuse_log(FUSE_LOG_ERR, "fv_queue_thread ppoll: %m\n"); break; } assert(poll_res == 1); if (pf[0].revents & (POLLERR | POLLHUP | POLLNVAL)) { fuse_log(FUSE_LOG_ERR, "%s: Unexpected poll revents %x Queue %d\n", __func__, pf[0].revents, qi->qidx); break; } assert(pf[0].revents & POLLIN); fuse_log(FUSE_LOG_DEBUG, "%s: Got queue event on Queue %d\n", __func__, qi->qidx); eventfd_t evalue; if (eventfd_read(qi->kick_fd, &evalue)) { fuse_log(FUSE_LOG_ERR, "Eventfd_read for queue: %m\n"); break; } /* out is from guest, in is too guest */ unsigned int in_bytes, out_bytes; vu_queue_get_avail_bytes(dev, q, &in_bytes, &out_bytes, ~0, ~0); fuse_log(FUSE_LOG_DEBUG, "%s: Queue %d gave evalue: %zx available: in: %u out: %u\n", __func__, qi->qidx, (size_t)evalue, in_bytes, out_bytes); while (1) { /* * An element contains one request and the space to send our * response They're spread over multiple descriptors in a * scatter/gather set and we can't trust the guest to keep them * still; so copy in/out. */ VuVirtqElement *elem = vu_queue_pop(dev, q, sizeof(VuVirtqElement)); if (!elem) { break; } qi->qe = elem; qi->reply_sent = false; if (!fbuf.mem) { fbuf.mem = malloc(se->bufsize); assert(fbuf.mem); assert(se->bufsize > sizeof(struct fuse_in_header)); } /* The 'out' part of the elem is from qemu */ unsigned int out_num = elem->out_num; struct iovec *out_sg = elem->out_sg; size_t out_len = iov_size(out_sg, out_num); fuse_log(FUSE_LOG_DEBUG, "%s: elem %d: with %d out desc of length %zd\n", __func__, elem->index, out_num, out_len); /* * The elem should contain a 'fuse_in_header' (in to fuse) * plus the data based on the len in the header. */ if (out_len < sizeof(struct fuse_in_header)) { fuse_log(FUSE_LOG_ERR, "%s: elem %d too short for in_header\n", __func__, elem->index); assert(0); /* TODO */ } if (out_len > se->bufsize) { fuse_log(FUSE_LOG_ERR, "%s: elem %d too large for buffer\n", __func__, elem->index); assert(0); /* TODO */ } copy_from_iov(&fbuf, out_num, out_sg); fbuf.size = out_len; /* TODO! Endianness of header */ /* TODO: Add checks for fuse_session_exited */ struct fuse_bufvec bufv = { .buf[0] = fbuf, .count = 1 }; fuse_session_process_buf_int(se, &bufv, &ch); if (!qi->reply_sent) { fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n", __func__, elem->index); /* I think we've still got to recycle the element */ vu_queue_push(dev, q, elem, 0); vu_queue_notify(dev, q); } qi->qe = NULL; free(elem); elem = NULL; } } pthread_mutex_destroy(&ch.lock); free(fbuf.mem); return NULL; } /* Callback from libvhost-user on start or stop of a queue */ static void fv_queue_set_started(VuDev *dev, int qidx, bool started) { struct fv_VuDev *vud = container_of(dev, struct fv_VuDev, dev); struct fv_QueueInfo *ourqi; fuse_log(FUSE_LOG_INFO, "%s: qidx=%d started=%d\n", __func__, qidx, started); assert(qidx >= 0); /* * Ignore additional request queues for now. passthrough_ll.c must be * audited for thread-safety issues first. It was written with a * well-behaved client in mind and may not protect against all types of * races yet. */ if (qidx > 1) { fuse_log(FUSE_LOG_ERR, "%s: multiple request queues not yet implemented, please only " "configure 1 request queue\n", __func__); exit(EXIT_FAILURE); } if (started) { /* Fire up a thread to watch this queue */ if (qidx >= vud->nqueues) { vud->qi = realloc(vud->qi, (qidx + 1) * sizeof(vud->qi[0])); assert(vud->qi); memset(vud->qi + vud->nqueues, 0, sizeof(vud->qi[0]) * (1 + (qidx - vud->nqueues))); vud->nqueues = qidx + 1; } if (!vud->qi[qidx]) { vud->qi[qidx] = calloc(sizeof(struct fv_QueueInfo), 1); assert(vud->qi[qidx]); vud->qi[qidx]->virtio_dev = vud; vud->qi[qidx]->qidx = qidx; } else { /* Shouldn't have been started */ assert(vud->qi[qidx]->kick_fd == -1); } ourqi = vud->qi[qidx]; ourqi->kick_fd = dev->vq[qidx].kick_fd; if (pthread_create(&ourqi->thread, NULL, fv_queue_thread, ourqi)) { fuse_log(FUSE_LOG_ERR, "%s: Failed to create thread for queue %d\n", __func__, qidx); assert(0); } } else { /* TODO: Kill the thread */ assert(qidx < vud->nqueues); ourqi = vud->qi[qidx]; ourqi->kick_fd = -1; } } static bool fv_queue_order(VuDev *dev, int qidx) { return false; } static const VuDevIface fv_iface = { .get_features = fv_get_features, .set_features = fv_set_features, /* Don't need process message, we've not got any at vhost-user level */ .queue_set_started = fv_queue_set_started, .queue_is_processed_in_order = fv_queue_order, }; /* * Main loop; this mostly deals with events on the vhost-user * socket itself, and not actual fuse data. */ int virtio_loop(struct fuse_session *se) { fuse_log(FUSE_LOG_INFO, "%s: Entry\n", __func__); while (!fuse_session_exited(se)) { struct pollfd pf[1]; pf[0].fd = se->vu_socketfd; pf[0].events = POLLIN; pf[0].revents = 0; fuse_log(FUSE_LOG_DEBUG, "%s: Waiting for VU event\n", __func__); int poll_res = ppoll(pf, 1, NULL, NULL); if (poll_res == -1) { if (errno == EINTR) { fuse_log(FUSE_LOG_INFO, "%s: ppoll interrupted, going around\n", __func__); continue; } fuse_log(FUSE_LOG_ERR, "virtio_loop ppoll: %m\n"); break; } assert(poll_res == 1); if (pf[0].revents & (POLLERR | POLLHUP | POLLNVAL)) { fuse_log(FUSE_LOG_ERR, "%s: Unexpected poll revents %x\n", __func__, pf[0].revents); break; } assert(pf[0].revents & POLLIN); fuse_log(FUSE_LOG_DEBUG, "%s: Got VU event\n", __func__); if (!vu_dispatch(&se->virtio_dev->dev)) { fuse_log(FUSE_LOG_ERR, "%s: vu_dispatch failed\n", __func__); break; } } fuse_log(FUSE_LOG_INFO, "%s: Exit\n", __func__); return 0; } static int fv_create_listen_socket(struct fuse_session *se) { struct sockaddr_un un; mode_t old_umask; /* Nothing to do if fd is already initialized */ if (se->vu_listen_fd >= 0) { return 0; } if (strlen(se->vu_socket_path) >= sizeof(un.sun_path)) { fuse_log(FUSE_LOG_ERR, "Socket path too long\n"); return -1; } /* * Create the Unix socket to communicate with qemu * based on QEMU's vhost-user-bridge */ unlink(se->vu_socket_path); strcpy(un.sun_path, se->vu_socket_path); size_t addr_len = sizeof(un); int listen_sock = socket(AF_UNIX, SOCK_STREAM, 0); if (listen_sock == -1) { fuse_log(FUSE_LOG_ERR, "vhost socket creation: %m\n"); return -1; } un.sun_family = AF_UNIX; /* * Unfortunately bind doesn't let you set the mask on the socket, * so set umask to 077 and restore it later. */ old_umask = umask(0077); if (bind(listen_sock, (struct sockaddr *)&un, addr_len) == -1) { fuse_log(FUSE_LOG_ERR, "vhost socket bind: %m\n"); umask(old_umask); return -1; } umask(old_umask); if (listen(listen_sock, 1) == -1) { fuse_log(FUSE_LOG_ERR, "vhost socket listen: %m\n"); return -1; } se->vu_listen_fd = listen_sock; return 0; } int virtio_session_mount(struct fuse_session *se) { int ret; ret = fv_create_listen_socket(se); if (ret < 0) { return ret; } se->fd = -1; fuse_log(FUSE_LOG_INFO, "%s: Waiting for vhost-user socket connection...\n", __func__); int data_sock = accept(se->vu_listen_fd, NULL, NULL); if (data_sock == -1) { fuse_log(FUSE_LOG_ERR, "vhost socket accept: %m\n"); close(se->vu_listen_fd); return -1; } close(se->vu_listen_fd); se->vu_listen_fd = -1; fuse_log(FUSE_LOG_INFO, "%s: Received vhost-user socket connection\n", __func__); /* TODO: Some cleanup/deallocation! */ se->virtio_dev = calloc(sizeof(struct fv_VuDev), 1); if (!se->virtio_dev) { fuse_log(FUSE_LOG_ERR, "%s: virtio_dev calloc failed\n", __func__); close(data_sock); return -1; } se->vu_socketfd = data_sock; se->virtio_dev->se = se; vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, fv_set_watch, fv_remove_watch, &fv_iface); return 0; }