| Message ID | 20240326133936.125332-4-sgarzare@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | vhost-user: support any POSIX system (tested on macOS, FreeBSD, OpenBSD) | expand |
On Tue, Mar 26, 2024 at 02:39:28PM +0100, Stefano Garzarella wrote: > libvhost-user will panic when receiving VHOST_USER_GET_INFLIGHT_FD > message if MFD_ALLOW_SEALING is not defined, since it's not able > to create a memfd. > > VHOST_USER_GET_INFLIGHT_FD is used only if > VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD is negotiated. So, let's mask > that feature if the backend is not able to properly handle these > messages. > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > subprojects/libvhost-user/libvhost-user.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c > index a11afd1960..1c361ffd51 100644 > --- a/subprojects/libvhost-user/libvhost-user.c > +++ b/subprojects/libvhost-user/libvhost-user.c > @@ -1674,6 +1674,16 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg) > features |= dev->iface->get_protocol_features(dev); > } > > + /* > + * If MFD_ALLOW_SEALING is not defined, we are not able to handle > + * VHOST_USER_GET_INFLIGHT_FD messages, since we can't create a memfd. > + * Those messages are used only if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD > + * is negotiated. A device implementation can enable it, so let's mask > + * it to avoid a runtime panic. > + */ > +#ifndef MFD_ALLOW_SEALING > + features &= ~(1ULL << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD); > +#endif Masking the feature out of advertisement is obviously correct. But should we also fix the code for handling VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD to return an error to any client that requests it in error when the feature was not advertised, instead of panicking? > vmsg_set_reply_u64(vmsg, features); > return true; > } > -- > 2.44.0 >
On Tue, Mar 26, 2024 at 09:36:54AM -0500, Eric Blake wrote: >On Tue, Mar 26, 2024 at 02:39:28PM +0100, Stefano Garzarella wrote: >> libvhost-user will panic when receiving VHOST_USER_GET_INFLIGHT_FD >> message if MFD_ALLOW_SEALING is not defined, since it's not able >> to create a memfd. >> >> VHOST_USER_GET_INFLIGHT_FD is used only if >> VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD is negotiated. So, let's mask >> that feature if the backend is not able to properly handle these >> messages. >> >> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> >> --- >> subprojects/libvhost-user/libvhost-user.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c >> index a11afd1960..1c361ffd51 100644 >> --- a/subprojects/libvhost-user/libvhost-user.c >> +++ b/subprojects/libvhost-user/libvhost-user.c >> @@ -1674,6 +1674,16 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg) >> features |= dev->iface->get_protocol_features(dev); >> } >> >> + /* >> + * If MFD_ALLOW_SEALING is not defined, we are not able to handle >> + * VHOST_USER_GET_INFLIGHT_FD messages, since we can't create a memfd. >> + * Those messages are used only if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD >> + * is negotiated. A device implementation can enable it, so let's mask >> + * it to avoid a runtime panic. >> + */ >> +#ifndef MFD_ALLOW_SEALING >> + features &= ~(1ULL << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD); >> +#endif > >Masking the feature out of advertisement is obviously correct. But >should we also fix the code for handling >VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD to return an error to any client >that requests it in error when the feature was not advertised, instead >of panicking? Totally agree! Do I send a separate patch from this series or include it in this series? I would do the former because this one is already long enough. Thanks, Stefano
diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c index a11afd1960..1c361ffd51 100644 --- a/subprojects/libvhost-user/libvhost-user.c +++ b/subprojects/libvhost-user/libvhost-user.c @@ -1674,6 +1674,16 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg) features |= dev->iface->get_protocol_features(dev); } + /* + * If MFD_ALLOW_SEALING is not defined, we are not able to handle + * VHOST_USER_GET_INFLIGHT_FD messages, since we can't create a memfd. + * Those messages are used only if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD + * is negotiated. A device implementation can enable it, so let's mask + * it to avoid a runtime panic. + */ +#ifndef MFD_ALLOW_SEALING + features &= ~(1ULL << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD); +#endif vmsg_set_reply_u64(vmsg, features); return true; }
libvhost-user will panic when receiving VHOST_USER_GET_INFLIGHT_FD message if MFD_ALLOW_SEALING is not defined, since it's not able to create a memfd. VHOST_USER_GET_INFLIGHT_FD is used only if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD is negotiated. So, let's mask that feature if the backend is not able to properly handle these messages. Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- subprojects/libvhost-user/libvhost-user.c | 10 ++++++++++ 1 file changed, 10 insertions(+)