From 85de8576a0b14aecc99136cfbf90e367fa2142cb Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 28 Nov 2016 23:16:54 +0100 Subject: bpf, xdp: allow to pass flags to dev_change_xdp_fd Add an IFLA_XDP_FLAGS attribute that can be passed for setting up XDP along with IFLA_XDP_FD, which eventually allows user space to implement typical add/replace/delete logic for programs. Right now, calling into dev_change_xdp_fd() will always replace previous programs. When passed XDP_FLAGS_UPDATE_IF_NOEXIST, we can handle this more graceful when requested by returning -EBUSY in case we try to attach a new program, but we find that another one is already attached. This will be used by upcoming front-end for iproute2 as well. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- net/core/dev.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'net/core/dev.c') diff --git a/net/core/dev.c b/net/core/dev.c index 048b46b..bffb525 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6692,26 +6692,42 @@ EXPORT_SYMBOL(dev_change_proto_down); * dev_change_xdp_fd - set or clear a bpf program for a device rx path * @dev: device * @fd: new program fd or negative value to clear + * @flags: xdp-related flags * * Set or clear a bpf program for a device */ -int dev_change_xdp_fd(struct net_device *dev, int fd) +int dev_change_xdp_fd(struct net_device *dev, int fd, u32 flags) { const struct net_device_ops *ops = dev->netdev_ops; struct bpf_prog *prog = NULL; - struct netdev_xdp xdp = {}; + struct netdev_xdp xdp; int err; + ASSERT_RTNL(); + if (!ops->ndo_xdp) return -EOPNOTSUPP; if (fd >= 0) { + if (flags & XDP_FLAGS_UPDATE_IF_NOEXIST) { + memset(&xdp, 0, sizeof(xdp)); + xdp.command = XDP_QUERY_PROG; + + err = ops->ndo_xdp(dev, &xdp); + if (err < 0) + return err; + if (xdp.prog_attached) + return -EBUSY; + } + prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP); if (IS_ERR(prog)) return PTR_ERR(prog); } + memset(&xdp, 0, sizeof(xdp)); xdp.command = XDP_SETUP_PROG; xdp.prog = prog; + err = ops->ndo_xdp(dev, &xdp); if (err < 0 && prog) bpf_prog_put(prog); -- cgit v1.1