Messages in this thread | | | Date | Fri, 15 May 2020 08:33:24 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH 4/4] ipv6: symbol_get to access a sit symbol |
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On Thu, May 14, 2020 at 05:53:55PM -0700, David Miller wrote: > You're not undoing one, but two levels of abstraction here. > > Is this "ipip6_tunnel_locate()" call part of the SIT ioctl implementation?
Yes. Take a look at the convoluted case handling the SIOCADDTUNNEL and SIOCCHGTUNNEL commands in ipip6_tunnel_ioctl.
> Where did it come from? Why are ->ndo_do_ioctl() implementations no longer > allowed from here?
The problem is that we feed kernel pointers to it, which requires set_fs address space overrides that I plan to kill off entirely.
> Honestly, this feels like a bit much.
My initial plan was to add a ->tunnel_ctl method to the net_device_ops, and lift the copy_{to,from}_user for SIOCADDTUNNEL, SIOCCHGTUNNEL, SIOCDELTUNNEL and maybe SIOCGETTUNNEL to net/socket.c. But that turned out to have two problems:
- first these ioctls names use SIOCDEVPRIVATE range, that can also be implemented by other drivers - the ip_tunnel_parm struture is only used by the ipv4 tunneling drivers (including sit), the "real" ipv6 tunnels use a ip6_tnl_parm or ip6_tnl_parm structure instead
But if you don't like the symbol_get approach, I could do the tunnel_ctl operation, just for the іpv4-ish tunnels, and only for the kernel callers.
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