Commit d4baa936 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
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bpf, xdp: Extract common XDP program attachment logic 



Further refactor XDP attachment code. dev_change_xdp_fd() is split into two
parts: getting bpf_progs from FDs and attachment logic, working with
bpf_progs. This makes attachment  logic a bit more straightforward and
prepares code for bpf_xdp_link inclusion, which will share the common logic.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-4-andriin@fb.com
parent 7f0a8382

net/core/dev.c

+91 −74
Original line number Diff line number Diff line
@@ -8815,111 +8815,128 @@ static void dev_xdp_uninstall(struct net_device *dev) 
	}

}



/**

 *	dev_change_xdp_fd - set or clear a bpf program for a device rx path

 *	@dev: device

 *	@extack: netlink extended ack

 *	@fd: new program fd or negative value to clear

 *	@expected_fd: old program fd that userspace expects to replace or clear

 *	@flags: xdp-related flags

 *

 *	Set or clear a bpf program for a device

 */

int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,

		      int fd, int expected_fd, u32 flags)

static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack,

			  struct bpf_prog *new_prog, struct bpf_prog *old_prog,

			  u32 flags)

{

	const struct net_device_ops *ops = dev->netdev_ops;

	enum bpf_xdp_mode mode = dev_xdp_mode(flags);

	bool offload = mode == XDP_MODE_HW;

	u32 prog_id, expected_id = 0;

	struct bpf_prog *prog;

	struct bpf_prog *cur_prog;

	enum bpf_xdp_mode mode;

	bpf_op_t bpf_op;

	int err;



	ASSERT_RTNL();



	bpf_op = dev_xdp_bpf_op(dev, mode);

	if (!bpf_op) {

		NL_SET_ERR_MSG(extack, "underlying driver does not support XDP in native mode");

		return -EOPNOTSUPP;

	/* just one XDP mode bit should be set, zero defaults to SKB mode */

	if (hweight32(flags & XDP_FLAGS_MODES) > 1) {

		NL_SET_ERR_MSG(extack, "Only one XDP mode flag can be set");

		return -EINVAL;

	}



	prog_id = dev_xdp_prog_id(dev, mode);

	if (flags & XDP_FLAGS_REPLACE) {

		if (expected_fd >= 0) {

			prog = bpf_prog_get_type_dev(expected_fd,

						     BPF_PROG_TYPE_XDP,

						     bpf_op == ops->ndo_bpf);

			if (IS_ERR(prog))

				return PTR_ERR(prog);

			expected_id = prog->aux->id;

			bpf_prog_put(prog);

	/* old_prog != NULL implies XDP_FLAGS_REPLACE is set */

	if (old_prog && !(flags & XDP_FLAGS_REPLACE)) {

		NL_SET_ERR_MSG(extack, "XDP_FLAGS_REPLACE is not specified");

		return -EINVAL;

	}



		if (prog_id != expected_id) {

	mode = dev_xdp_mode(flags);

	cur_prog = dev_xdp_prog(dev, mode);

	if ((flags & XDP_FLAGS_REPLACE) && cur_prog != old_prog) {

		NL_SET_ERR_MSG(extack, "Active program does not match expected");

		return -EEXIST;

	}

	if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {

		NL_SET_ERR_MSG(extack, "XDP program already attached");

		return -EBUSY;

	}

	if (fd >= 0) {



	if (new_prog) {

		bool offload = mode == XDP_MODE_HW;

		enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB

					       ? XDP_MODE_DRV : XDP_MODE_SKB;



		if (!offload && dev_xdp_prog_id(dev, other_mode)) {

		if (!offload && dev_xdp_prog(dev, other_mode)) {

			NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time");

			return -EEXIST;

		}



		if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && prog_id) {

			NL_SET_ERR_MSG(extack, "XDP program already attached");

			return -EBUSY;

		}



		prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,

					     bpf_op == ops->ndo_bpf);

		if (IS_ERR(prog))

			return PTR_ERR(prog);



		if (!offload && bpf_prog_is_dev_bound(prog->aux)) {

		if (!offload && bpf_prog_is_dev_bound(new_prog->aux)) {

			NL_SET_ERR_MSG(extack, "Using device-bound program without HW_MODE flag is not supported");

			bpf_prog_put(prog);

			return -EINVAL;

		}



		if (prog->expected_attach_type == BPF_XDP_DEVMAP) {

		if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) {

			NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");

			bpf_prog_put(prog);

			return -EINVAL;

		}



		if (prog->expected_attach_type == BPF_XDP_CPUMAP) {

			NL_SET_ERR_MSG(extack,

				       "BPF_XDP_CPUMAP programs can not be attached to a device");

			bpf_prog_put(prog);

		if (new_prog->expected_attach_type == BPF_XDP_CPUMAP) {

			NL_SET_ERR_MSG(extack, "BPF_XDP_CPUMAP programs can not be attached to a device");

			return -EINVAL;

		}



		/* prog->aux->id may be 0 for orphaned device-bound progs */

		if (prog->aux->id && prog->aux->id == prog_id) {

			bpf_prog_put(prog);

			return 0;

	}

	} else {

		if (!prog_id)

			return 0;

		prog = NULL;



	/* don't call drivers if the effective program didn't change */

	if (new_prog != cur_prog) {

		bpf_op = dev_xdp_bpf_op(dev, mode);

		if (!bpf_op) {

			NL_SET_ERR_MSG(extack, "Underlying driver does not support XDP in native mode");

			return -EOPNOTSUPP;

		}



	err = dev_xdp_install(dev, mode, bpf_op, extack, flags, prog);

	if (err < 0 && prog) {

		bpf_prog_put(prog);

		err = dev_xdp_install(dev, mode, bpf_op, extack, flags, new_prog);

		if (err)

			return err;

	}

	dev_xdp_set_prog(dev, mode, prog);



	dev_xdp_set_prog(dev, mode, new_prog);

	if (cur_prog)

		bpf_prog_put(cur_prog);



	return 0;

}



/**

 *	dev_change_xdp_fd - set or clear a bpf program for a device rx path

 *	@dev: device

 *	@extack: netlink extended ack

 *	@fd: new program fd or negative value to clear

 *	@expected_fd: old program fd that userspace expects to replace or clear

 *	@flags: xdp-related flags

 *

 *	Set or clear a bpf program for a device

 */

int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,

		      int fd, int expected_fd, u32 flags)

{

	enum bpf_xdp_mode mode = dev_xdp_mode(flags);

	struct bpf_prog *new_prog = NULL, *old_prog = NULL;

	int err;



	ASSERT_RTNL();



	if (fd >= 0) {

		new_prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,

						 mode != XDP_MODE_SKB);

		if (IS_ERR(new_prog))

			return PTR_ERR(new_prog);

	}



	if (expected_fd >= 0) {

		old_prog = bpf_prog_get_type_dev(expected_fd, BPF_PROG_TYPE_XDP,

						 mode != XDP_MODE_SKB);

		if (IS_ERR(old_prog)) {

			err = PTR_ERR(old_prog);

			old_prog = NULL;

			goto err_out;

		}

	}



	err = dev_xdp_attach(dev, extack, new_prog, old_prog, flags);



err_out:

	if (err && new_prog)

		bpf_prog_put(new_prog);

	if (old_prog)

		bpf_prog_put(old_prog);

	return err;

}



/**

 *	dev_new_index	-	allocate an ifindex

 *	@net: the applicable net namespace

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