Commit 85de8576 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0f29f05b

include/linux/netdevice.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

include/uapi/linux/if_link.h

+4 −0
Original line number Diff line number Diff line
@@ -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,

};

net/core/dev.c

+18 −2
Original line number Diff line number Diff line
@@ -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);

net/core/rtnetlink.c

+13 −1
Original line number Diff line number Diff line
@@ -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;

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