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From 426cb49d423f5386b2d869009e29d7061e51b998 Mon Sep 17 00:00:00 2001
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From: "plai@redhat.com" <plai@redhat.com>
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Date: Thu, 21 Jun 2018 18:54:38 +0200
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Subject: [PATCH 159/268] vhost-user: support receiving file descriptors in
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 slave_read
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RH-Author: plai@redhat.com
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Message-id: <1529607285-9942-4-git-send-email-plai@redhat.com>
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Patchwork-id: 80933
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O-Subject: [RHEL7.6 PATCH BZ 1526645 03/10] vhost-user: support receiving file descriptors in slave_read
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Bugzilla: 1526645
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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RH-Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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From: Tiwei Bie <tiwei.bie@intel.com>
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Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit 1f3a4519b1c107b5db2434b30638353978366b4d)
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Signed-off-by: Paul Lai <plai@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/virtio/vhost-user.c | 41 ++++++++++++++++++++++++++++++++++++++++-
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 1 file changed, 40 insertions(+), 1 deletion(-)
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diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
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index 38da869..85d8fd2 100644
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--- a/hw/virtio/vhost-user.c
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+++ b/hw/virtio/vhost-user.c
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@@ -852,14 +852,44 @@ static void slave_read(void *opaque)
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     VhostUserHeader hdr = { 0, };
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     VhostUserPayload payload = { 0, };
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     int size, ret = 0;
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+    struct iovec iov;
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+    struct msghdr msgh;
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+    int fd = -1;
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+    char control[CMSG_SPACE(sizeof(fd))];
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+    struct cmsghdr *cmsg;
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+    size_t fdsize;
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+
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+    memset(&msgh, 0, sizeof(msgh));
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+    msgh.msg_iov = &iov;
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+    msgh.msg_iovlen = 1;
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+    msgh.msg_control = control;
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+    msgh.msg_controllen = sizeof(control);
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     /* Read header */
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-    size = read(u->slave_fd, &hdr, VHOST_USER_HDR_SIZE);
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+    iov.iov_base = &hdr;
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+    iov.iov_len = VHOST_USER_HDR_SIZE;
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+
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+    size = recvmsg(u->slave_fd, &msgh, 0);
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     if (size != VHOST_USER_HDR_SIZE) {
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         error_report("Failed to read from slave.");
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         goto err;
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     }
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+    if (msgh.msg_flags & MSG_CTRUNC) {
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+        error_report("Truncated message.");
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+        goto err;
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+    }
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+
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+    for (cmsg = CMSG_FIRSTHDR(&msgh); cmsg != NULL;
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+         cmsg = CMSG_NXTHDR(&msgh, cmsg)) {
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+            if (cmsg->cmsg_level == SOL_SOCKET &&
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+                cmsg->cmsg_type == SCM_RIGHTS) {
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+                    fdsize = cmsg->cmsg_len - CMSG_LEN(0);
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+                    memcpy(&fd, CMSG_DATA(cmsg), fdsize);
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+                    break;
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+            }
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+    }
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+
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     if (hdr.size > VHOST_USER_PAYLOAD_SIZE) {
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         error_report("Failed to read msg header."
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                 " Size %d exceeds the maximum %zu.", hdr.size,
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@@ -883,9 +913,15 @@ static void slave_read(void *opaque)
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         break;
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     default:
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         error_report("Received unexpected msg type.");
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+        if (fd != -1) {
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+            close(fd);
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+        }
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         ret = -EINVAL;
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     }
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+    /* Message handlers need to make sure that fd will be consumed. */
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+    fd = -1;
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+
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     /*
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      * REPLY_ACK feature handling. Other reply types has to be managed
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      * directly in their request handlers.
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@@ -918,6 +954,9 @@ err:
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     qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
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     close(u->slave_fd);
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     u->slave_fd = -1;
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+    if (fd != -1) {
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+        close(fd);
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+    }
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     return;
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 }
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-- 
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1.8.3.1
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