From 85de8576a0b14aecc99136cfbf90e367fa2142cb Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 28 Nov 2016 23:16:54 +0100 Subject: [PATCH] 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 --- include/linux/netdevice.h | 2 +- include/uapi/linux/if_link.h | 4 ++++ net/core/dev.c | 20 ++++++++++++++++++-- net/core/rtnetlink.c | 14 +++++++++++++- 4 files changed, 36 insertions(+), 4 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 4ffcd874cc20..3755317cc6a9 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3253,7 +3253,7 @@ int dev_get_phys_port_id(struct net_device *dev, int dev_get_phys_port_name(struct net_device *dev, char *name, size_t len); int dev_change_proto_down(struct net_device *dev, bool proto_down); -int dev_change_xdp_fd(struct net_device *dev, int fd); +int dev_change_xdp_fd(struct net_device *dev, int fd, u32 flags); struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *dev); struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, struct netdev_queue *txq, int *ret); diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h index 92b2d4928bf1..6b13e591abc9 100644 --- a/include/uapi/linux/if_link.h +++ b/include/uapi/linux/if_link.h @@ -876,10 +876,14 @@ enum { /* XDP section */ +#define XDP_FLAGS_UPDATE_IF_NOEXIST (1U << 0) +#define XDP_FLAGS_MASK (XDP_FLAGS_UPDATE_IF_NOEXIST) + enum { IFLA_XDP_UNSPEC, IFLA_XDP_FD, IFLA_XDP_ATTACHED, + IFLA_XDP_FLAGS, __IFLA_XDP_MAX, }; diff --git a/net/core/dev.c b/net/core/dev.c index 048b46b7c92a..bffb5253e778 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); diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 4e60525ea586..bd85570e6e4b 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1505,6 +1505,7 @@ static const struct nla_policy ifla_port_policy[IFLA_PORT_MAX+1] = { static const struct nla_policy ifla_xdp_policy[IFLA_XDP_MAX + 1] = { [IFLA_XDP_FD] = { .type = NLA_S32 }, [IFLA_XDP_ATTACHED] = { .type = NLA_U8 }, + [IFLA_XDP_FLAGS] = { .type = NLA_U32 }, }; static const struct rtnl_link_ops *linkinfo_to_kind_ops(const struct nlattr *nla) @@ -2164,6 +2165,7 @@ static int do_setlink(const struct sk_buff *skb, if (tb[IFLA_XDP]) { struct nlattr *xdp[IFLA_XDP_MAX + 1]; + u32 xdp_flags = 0; err = nla_parse_nested(xdp, IFLA_XDP_MAX, tb[IFLA_XDP], ifla_xdp_policy); @@ -2174,9 +2176,19 @@ static int do_setlink(const struct sk_buff *skb, err = -EINVAL; goto errout; } + + if (xdp[IFLA_XDP_FLAGS]) { + xdp_flags = nla_get_u32(xdp[IFLA_XDP_FLAGS]); + if (xdp_flags & ~XDP_FLAGS_MASK) { + err = -EINVAL; + goto errout; + } + } + if (xdp[IFLA_XDP_FD]) { err = dev_change_xdp_fd(dev, - nla_get_s32(xdp[IFLA_XDP_FD])); + nla_get_s32(xdp[IFLA_XDP_FD]), + xdp_flags); if (err) goto errout; status |= DO_SETLINK_NOTIFY; -- 2.20.1