Merge remote-tracking branch 'remotes/dagrh/tags/pull-virtiofs-20211026' into staging

Virtiofsd pull 2021-10-26

New 'unsupported' feature for xattr mapping
  Good for hiding selinux

Plus some tidy ups and error handling.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

# gpg: Signature made Tue 26 Oct 2021 03:28:44 AM PDT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]

* remotes/dagrh/tags/pull-virtiofs-20211026:
  virtiofsd: Error on bad socket group name
  virtiofsd: Add a helper to stop all queues
  virtiofsd: Add a helper to send element on virtqueue
  virtiofsd: Remove unused virtio_fs_config definition
  virtiofsd: xattr mapping add a new type "unsupported"

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

3 files changed, 58 insertions, 45 deletions

diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst
index b208f2a..cc31402 100644
--- a/docs/tools/virtiofsd.rst
+++ b/docs/tools/virtiofsd.rst
@@ -183,6 +183,12 @@ Using ':' as the separator a rule is of the form:
   'ok' as either an explicit terminator or for special handling of certain
   patterns.
 
+- 'unsupported' - If a client tries to use a name matching 'key' it's
+  denied using ENOTSUP; when the server passes an attribute
+  name matching 'prepend' it's hidden.  In many ways it's use is very like
+  'ok' as either an explicit terminator or for special handling of certain
+  patterns.
+
 **key** is a string tested as a prefix on an attribute name originating
 on the client.  It maybe empty in which case a 'client' rule
 will always match on client names.
diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index 8f4fd16..60b9647 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -82,12 +82,6 @@ struct fv_VuDev {
     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)
 {
@@ -249,6 +243,21 @@ static void vu_dispatch_unlock(struct fv_VuDev *vud)
     assert(ret == 0);
 }
 
+static void vq_send_element(struct fv_QueueInfo *qi, VuVirtqElement *elem,
+                            ssize_t len)
+{
+    struct fuse_session *se = qi->virtio_dev->se;
+    VuDev *dev = &se->virtio_dev->dev;
+    VuVirtq *q = vu_get_queue(dev, qi->qidx);
+
+    vu_dispatch_rdlock(qi->virtio_dev);
+    pthread_mutex_lock(&qi->vq_lock);
+    vu_queue_push(dev, q, elem, len);
+    vu_queue_notify(dev, q);
+    pthread_mutex_unlock(&qi->vq_lock);
+    vu_dispatch_unlock(qi->virtio_dev);
+}
+
 /*
  * 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
@@ -259,8 +268,6 @@ int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch,
 {
     FVRequest *req = container_of(ch, FVRequest, ch);
     struct fv_QueueInfo *qi = ch->qi;
-    VuDev *dev = &se->virtio_dev->dev;
-    VuVirtq *q = vu_get_queue(dev, qi->qidx);
     VuVirtqElement *elem = &req->elem;
     int ret = 0;
 
@@ -302,13 +309,7 @@ int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch,
 
     copy_iov(iov, count, in_sg, in_num, tosend_len);
 
-    vu_dispatch_rdlock(qi->virtio_dev);
-    pthread_mutex_lock(&qi->vq_lock);
-    vu_queue_push(dev, q, elem, tosend_len);
-    vu_queue_notify(dev, q);
-    pthread_mutex_unlock(&qi->vq_lock);
-    vu_dispatch_unlock(qi->virtio_dev);
-
+    vq_send_element(qi, elem, tosend_len);
     req->reply_sent = true;
 
 err:
@@ -327,8 +328,6 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
 {
     FVRequest *req = container_of(ch, FVRequest, ch);
     struct fv_QueueInfo *qi = ch->qi;
-    VuDev *dev = &se->virtio_dev->dev;
-    VuVirtq *q = vu_get_queue(dev, qi->qidx);
     VuVirtqElement *elem = &req->elem;
     int ret = 0;
     g_autofree struct iovec *in_sg_cpy = NULL;
@@ -436,12 +435,7 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
         out_sg->len = tosend_len;
     }
 
-    vu_dispatch_rdlock(qi->virtio_dev);
-    pthread_mutex_lock(&qi->vq_lock);
-    vu_queue_push(dev, q, elem, tosend_len);
-    vu_queue_notify(dev, q);
-    pthread_mutex_unlock(&qi->vq_lock);
-    vu_dispatch_unlock(qi->virtio_dev);
+    vq_send_element(qi, elem, tosend_len);
     req->reply_sent = true;
     return 0;
 }
@@ -453,7 +447,6 @@ static void fv_queue_worker(gpointer data, gpointer user_data)
 {
     struct fv_QueueInfo *qi = user_data;
     struct fuse_session *se = qi->virtio_dev->se;
-    struct VuDev *dev = &qi->virtio_dev->dev;
     FVRequest *req = data;
     VuVirtqElement *elem = &req->elem;
     struct fuse_buf fbuf = {};
@@ -595,17 +588,9 @@ out:
 
     /* If the request has no reply, still recycle the virtqueue element */
     if (!req->reply_sent) {
-        struct VuVirtq *q = vu_get_queue(dev, qi->qidx);
-
         fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n", __func__,
                  elem->index);
-
-        vu_dispatch_rdlock(qi->virtio_dev);
-        pthread_mutex_lock(&qi->vq_lock);
-        vu_queue_push(dev, q, elem, 0);
-        vu_queue_notify(dev, q);
-        pthread_mutex_unlock(&qi->vq_lock);
-        vu_dispatch_unlock(qi->virtio_dev);
+        vq_send_element(qi, elem, 0);
     }
 
     pthread_mutex_destroy(&req->ch.lock);
@@ -755,6 +740,18 @@ static void fv_queue_cleanup_thread(struct fv_VuDev *vud, int qidx)
     vud->qi[qidx] = NULL;
 }
 
+static void stop_all_queues(struct fv_VuDev *vud)
+{
+    for (int i = 0; i < vud->nqueues; i++) {
+        if (!vud->qi[i]) {
+            continue;
+        }
+
+        fuse_log(FUSE_LOG_INFO, "%s: Stopping queue %d thread\n", __func__, i);
+        fv_queue_cleanup_thread(vud, i);
+    }
+}
+
 /* Callback from libvhost-user on start or stop of a queue */
 static void fv_queue_set_started(VuDev *dev, int qidx, bool started)
 {
@@ -885,15 +882,7 @@ int virtio_loop(struct fuse_session *se)
      * Make sure all fv_queue_thread()s quit on exit, as we're about to
      * free virtio dev and fuse session, no one should access them anymore.
      */
-    for (int i = 0; i < se->virtio_dev->nqueues; i++) {
-        if (!se->virtio_dev->qi[i]) {
-            continue;
-        }
-
-        fuse_log(FUSE_LOG_INFO, "%s: Stopping queue %d thread\n", __func__, i);
-        fv_queue_cleanup_thread(se->virtio_dev, i);
-    }
-
+    stop_all_queues(se->virtio_dev);
     fuse_log(FUSE_LOG_INFO, "%s: Exit\n", __func__);
 
     return 0;
@@ -999,6 +988,13 @@ static int fv_create_listen_socket(struct fuse_session *se)
                          "vhost socket failed to set group to %s (%d): %m\n",
                          se->vu_socket_group, g->gr_gid);
             }
+        } else {
+            fuse_log(FUSE_LOG_ERR,
+                     "vhost socket: unable to find group '%s'\n",
+                     se->vu_socket_group);
+            close(listen_sock);
+            umask(old_umask);
+            return -1;
         }
     }
     umask(old_umask);
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 38b2af8..64b5b4f 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -2465,6 +2465,11 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi,
  * Automatically reversed on read
  */
 #define XATTR_MAP_FLAG_PREFIX  (1 <<  2)
+/*
+ * The attribute is unsupported;
+ * ENOTSUP on write, hidden on read.
+ */
+#define XATTR_MAP_FLAG_UNSUPPORTED     (1 <<  3)
 
 /* scopes */
 /* Apply rule to get/set/remove */
@@ -2636,6 +2641,8 @@ static void parse_xattrmap(struct lo_data *lo)
             tmp_entry.flags |= XATTR_MAP_FLAG_OK;
         } else if (strstart(map, "bad", &map)) {
             tmp_entry.flags |= XATTR_MAP_FLAG_BAD;
+        } else if (strstart(map, "unsupported", &map)) {
+            tmp_entry.flags |= XATTR_MAP_FLAG_UNSUPPORTED;
         } else if (strstart(map, "map", &map)) {
             /*
              * map is sugar that adds a number of rules, and must be
@@ -2646,8 +2653,8 @@ static void parse_xattrmap(struct lo_data *lo)
         } else {
             fuse_log(FUSE_LOG_ERR,
                      "%s: Unexpected type;"
-                     "Expecting 'prefix', 'ok', 'bad' or 'map' in rule %zu\n",
-                     __func__, lo->xattr_map_nentries);
+                     "Expecting 'prefix', 'ok', 'bad', 'unsupported' or 'map'"
+                     " in rule %zu\n", __func__, lo->xattr_map_nentries);
             exit(1);
         }
 
@@ -2749,6 +2756,9 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name,
             if (cur_entry->flags & XATTR_MAP_FLAG_BAD) {
                 return -EPERM;
             }
+            if (cur_entry->flags & XATTR_MAP_FLAG_UNSUPPORTED) {
+                return -ENOTSUP;
+            }
             if (cur_entry->flags & XATTR_MAP_FLAG_OK) {
                 /* Unmodified name */
                 return 0;
@@ -2788,7 +2798,8 @@ static int xattr_map_server(const struct lo_data *lo, const char *server_name,
 
         if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) &&
             (strstart(server_name, cur_entry->prepend, &end))) {
-            if (cur_entry->flags & XATTR_MAP_FLAG_BAD) {
+            if (cur_entry->flags & XATTR_MAP_FLAG_BAD ||
+                cur_entry->flags & XATTR_MAP_FLAG_UNSUPPORTED) {
                 return -ENODATA;
             }
             if (cur_entry->flags & XATTR_MAP_FLAG_OK) {