Re: [Qemu-devel] [PATCH] linux-user: check if NETLINK_ROUTE is available

[Riku Voipio]

On Thu, Jun 02, 2016 at 10:14:15PM +0200, Laurent Vivier wrote:
> Some IFLA_* symbols can be missing in the host linux/if_link.h,
> but as they are enums and not "#defines", check in "configure" if
> last known  (IFLA_PROTO_DOWN) is available and if not, disable
> management of NETLINK_ROUTE protocol.
> 
> Signed-off-by: Laurent Vivier <address@hidden>
> ---
> Note:
>    This patch must be applied on top of the series:
>    [PATCH v2 0/3] linux-user: netlink support

Generally speaking this should be squashed to 1/3 because
else bisecting builds may fail in between that patch and this
patch. In this case I don't care because we are talking about
relatively old distributions that would be affected.

>  configure            | 15 +++++++++++++++
>  linux-user/syscall.c | 18 ++++++++++++++----
>  2 files changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/configure b/configure
> index b5aab72..294d791 100755
> --- a/configure
> +++ b/configure
> @@ -4526,6 +4526,17 @@ if compile_prog "" "" ; then
>      have_fsxattr=yes
>  fi
>  
> +have_rtnetlink=no
> +cat > $TMPC << EOF
> +#include <linux/rtnetlink.h>
> +int main(void) {
> +  return IFLA_PROTO_DOWN;
> +}
> +EOF
> +if compile_prog "" "" ; then
> +    have_rtnetlink=yes
> +fi
> +
>  ##########################################
>  # End of CC checks
>  # After here, no more $cc or $ld runs
> @@ -5461,6 +5472,10 @@ if test "$rdma" = "yes" ; then
>    echo "CONFIG_RDMA=y" >> $config_host_mak
>  fi
>  
> +if test "$have_rtnetlink" = "yes" ; then
> +  echo "CONFIG_RTNETLINK=y" >> $config_host_mak
> +fi
> +
>  # Hold two types of flag:
>  #   CONFIG_THREAD_SETNAME_BYTHREAD  - we've got a way of setting the name on
>  #                                     a thread we have a handle to
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index da48ba4..7c88d63 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -104,7 +104,9 @@ int __clone2(int (*fn)(void *), void *child_stack_base,
>  #include "linux_loop.h"
>  #include <linux/if_packet.h>
>  #include <linux/netlink.h>
> +#ifdef CONFIG_RTNETLINK
>  #include <linux/rtnetlink.h>
> +#endif
>  #include <linux/audit.h>
>  #include "uname.h"
>  
> @@ -1629,6 +1631,7 @@ static abi_long target_to_host_for_each_nlmsg(struct 
> nlmsghdr *nlh,
>      return 0;
>  }
>  
> +#ifdef CONFIG_RTNETLINK
>  static abi_long host_to_target_for_each_rtattr(struct rtattr *rtattr,
>                                                 size_t len,
>                                                 abi_long 
> (*host_to_target_rtattr)
> @@ -2043,6 +2046,7 @@ static abi_long target_to_host_nlmsg_route(struct 
> nlmsghdr *nlh, size_t len)
>  {
>      return target_to_host_for_each_nlmsg(nlh, len, 
> target_to_host_data_route);
>  }
> +#endif /* CONFIG_RTNETLINK */
>  
>  static abi_long host_to_target_data_audit(struct nlmsghdr *nlh)
>  {
> @@ -2794,6 +2798,7 @@ static TargetFdTrans target_packet_trans = {
>      .target_to_host_addr = packet_target_to_host_sockaddr,
>  };
>  
> +#ifdef CONFIG_RTNETLINK
>  static abi_long netlink_route_target_to_host(void *buf, size_t len)
>  {
>      return target_to_host_nlmsg_route(buf, len);
> @@ -2808,6 +2813,7 @@ static TargetFdTrans target_netlink_route_trans = {
>      .target_to_host_data = netlink_route_target_to_host,
>      .host_to_target_data = netlink_route_host_to_target,
>  };
> +#endif /* CONFIG_RTNETLINK */
>  
>  static abi_long netlink_audit_target_to_host(void *buf, size_t len)
>  {
> @@ -2835,10 +2841,12 @@ static abi_long do_socket(int domain, int type, int 
> protocol)
>          return ret;
>      }
>  
> -    if (domain == PF_NETLINK &&
> -        !(protocol == NETLINK_ROUTE ||
> -          protocol == NETLINK_KOBJECT_UEVENT ||
> -          protocol == NETLINK_AUDIT)) {
> +    if (domain == PF_NETLINK && !(
> +#ifdef CONFIG_RTNETLINK
> +         protocol == NETLINK_ROUTE ||
> +#endif
> +         protocol == NETLINK_KOBJECT_UEVENT ||
> +         protocol == NETLINK_AUDIT)) {
>          return -EPFNOSUPPORT;
>      }
>  
> @@ -2857,9 +2865,11 @@ static abi_long do_socket(int domain, int type, int 
> protocol)
>              fd_trans_register(ret, &target_packet_trans);
>          } else if (domain == PF_NETLINK) {
>              switch (protocol) {
> +#ifdef CONFIG_RTNETLINK
>              case NETLINK_ROUTE:
>                  fd_trans_register(ret, &target_netlink_route_trans);
>                  break;
> +#endif
>              case NETLINK_KOBJECT_UEVENT:
>                  /* nothing to do: messages are strings */
>                  break;
> -- 
> 2.5.5
>