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Re: [Qemu-devel] [virtio-dev] Re: [PATCH v3 3/6] vhost-user: support rec
From: |
Tiwei Bie |
Subject: |
Re: [Qemu-devel] [virtio-dev] Re: [PATCH v3 3/6] vhost-user: support receiving file descriptors in slave_read |
Date: |
Thu, 24 May 2018 07:12:15 +0800 |
User-agent: |
Mutt/1.9.5 (2018-04-13) |
On Thu, May 24, 2018 at 12:25:23AM +0300, Michael S. Tsirkin wrote:
> On Thu, Apr 12, 2018 at 11:12:29PM +0800, Tiwei Bie wrote:
> > Signed-off-by: Tiwei Bie <address@hidden>
>
>
> Thinking about it, I think we should add a protocol
> feature for this. This way remote can find out whether
> it's safe to send this data to us.
Okay, I can add a protocol feature for this.
Do you think it's OK to keep this patch as is
(this patch just extends slave_read() to support
receiving file descriptors) and introduce the
new protocol feature in a new patch to allow
backends to send file descriptors?
Best regards,
Tiwei Bie
>
> > ---
> > hw/virtio/vhost-user.c | 41 ++++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 40 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > index 91edd95453..9cea2c8c51 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -854,14 +854,44 @@ static void slave_read(void *opaque)
> > VhostUserHeader hdr = { 0, };
> > VhostUserPayload payload = { 0, };
> > int size, ret = 0;
> > + struct iovec iov;
> > + struct msghdr msgh;
> > + int fd = -1;
> > + char control[CMSG_SPACE(sizeof(fd))];
> > + struct cmsghdr *cmsg;
> > + size_t fdsize;
> > +
> > + memset(&msgh, 0, sizeof(msgh));
> > + msgh.msg_iov = &iov;
> > + msgh.msg_iovlen = 1;
> > + msgh.msg_control = control;
> > + msgh.msg_controllen = sizeof(control);
> >
> > /* Read header */
> > - size = read(u->slave_fd, &hdr, VHOST_USER_HDR_SIZE);
> > + iov.iov_base = &hdr;
> > + iov.iov_len = VHOST_USER_HDR_SIZE;
> > +
> > + size = recvmsg(u->slave_fd, &msgh, 0);
> > if (size != VHOST_USER_HDR_SIZE) {
> > error_report("Failed to read from slave.");
> > goto err;
> > }
> >
> > + if (msgh.msg_flags & MSG_CTRUNC) {
> > + error_report("Truncated message.");
> > + goto err;
> > + }
> > +
> > + for (cmsg = CMSG_FIRSTHDR(&msgh); cmsg != NULL;
> > + cmsg = CMSG_NXTHDR(&msgh, cmsg)) {
> > + if (cmsg->cmsg_level == SOL_SOCKET &&
> > + cmsg->cmsg_type == SCM_RIGHTS) {
> > + fdsize = cmsg->cmsg_len - CMSG_LEN(0);
> > + memcpy(&fd, CMSG_DATA(cmsg), fdsize);
> > + break;
> > + }
> > + }
> > +
> > if (hdr.size > VHOST_USER_PAYLOAD_SIZE) {
> > error_report("Failed to read msg header."
> > " Size %d exceeds the maximum %zu.", hdr.size,
> > @@ -885,9 +915,15 @@ static void slave_read(void *opaque)
> > break;
> > default:
> > error_report("Received unexpected msg type.");
> > + if (fd != -1) {
> > + close(fd);
> > + }
> > ret = -EINVAL;
> > }
> >
> > + /* Message handlers need to make sure that fd will be consumed. */
> > + fd = -1;
> > +
> > /*
> > * REPLY_ACK feature handling. Other reply types has to be managed
> > * directly in their request handlers.
> > @@ -920,6 +956,9 @@ err:
> > qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
> > close(u->slave_fd);
> > u->slave_fd = -1;
> > + if (fd != -1) {
> > + close(fd);
> > + }
> > return;
> > }
> >
> > --
> > 2.11.0
>
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