> From: Stefan Hajnoczi [mailto:stefanha@xxxxxxxxxx] > On Fri, Aug 18, 2017 at 10:23:54PM +0000, Dexuan Cui wrote: > > > > +static bool hvs_stream_allow(u32 cid, u32 port) > > > > +{ > > > > + static const u32 valid_cids[] = { > > > > + VMADDR_CID_ANY, > > > > > > Is this for loopback? > > > > No, we don't support lookback in Linux VM, at least for now. > > In our Linux implementation, Linux VM can only connect to the host, and > > here when Linux VM calls connect(), I treat VMADDR_CID_ANY > > the same as VMADDR_CID_HOST. > > VMCI and virtio-vsock do not treat connect(VMADDR_CID_ANY) the same as > connect(VMADDR_CID_HOST). It is an error to connect to VMADDR_CID_ANY. Ok. Then I'll only allow VMADDR_CID_HOST as the destination CID, since we don't support loopback mode. > > > > + /* The host's port range [MIN_HOST_EPHEMERAL_PORT, 0xFFFFFFFF) > > > is > > > > + * reserved as ephemeral ports, which are used as the host's ports > > > > + * when the host initiates connections. > > > > + */ > > > > + if (port > MAX_HOST_LISTEN_PORT) > > > > + return false; > > > > > > Without this if statement the guest will attempt to connect. I guess > > > there will be no listen sockets above MAX_HOST_LISTEN_PORT, so the > > > connection attempt will fail. > > > > You're correct. > > To use the vsock common infrastructure, we have to map Hyper-V's > > GUID <VM_ID, Service_ID> to int <cid, port>, and hence we must limit > > the port range we can listen() on to [0, MAX_LISTEN_PORT], i.e. > > we can only use half of the whole 32-bit port space for listen(). > > This is detailed in the long comments starting at about Line 100. > > > > > ...but hardcode this knowledge into the guest driver? > > I'd like the guest's connect() to fail immediately here. > > IMO this is better than a connect timeout. :-) > > Thanks for explaining. Perhaps the comment could be updated: > > /* The host's port range [MIN_HOST_EPHEMERAL_PORT, 0xFFFFFFFF) is > * reserved as ephemeral ports, which are used as the host's ports when > * the host initiates connections. > * > * Perform this check in the guest so an immediate error is produced > * instead of a timeout. > */ > > Stefan Thank you, Stefan! Please see the below for the updated version of the function: static bool hvs_stream_allow(u32 cid, u32 port) { /* The host's port range [MIN_HOST_EPHEMERAL_PORT, 0xFFFFFFFF) is * reserved as ephemeral ports, which are used as the host's ports * when the host initiates connections. * * Perform this check in the guest so an immediate error is produced * instead of a timeout. */ if (port > MAX_HOST_LISTEN_PORT) return false; if (cid == VMADDR_CID_HOST) return true; return false; } I'll send a v2 of the patch later today. -- Dexuan _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
