From 7f0a838254bdd9114b978ef2541a6ce330307e9e Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 21 Jul 2020 23:45:55 -0700 Subject: [PATCH] bpf, xdp: Maintain info on attached XDP BPF programs in net_device Instead of delegating to drivers, maintain information about which BPF programs are attached in which XDP modes (generic/skb, driver, or hardware) locally in net_device. This effectively obsoletes XDP_QUERY_PROG command. Such re-organization simplifies existing code already. But it also allows to further add bpf_link-based XDP attachments without drivers having to know about any of this at all, which seems like a good setup. XDP_SETUP_PROG/XDP_SETUP_PROG_HW are just low-level commands to driver to install/uninstall active BPF program. All the higher-level concerns about prog/link interaction will be contained within generic driver-agnostic logic. All the XDP_QUERY_PROG calls to driver in dev_xdp_uninstall() were removed. It's not clear for me why dev_xdp_uninstall() were passing previous prog_flags when resetting installed programs. That seems unnecessary, plus most drivers don't populate prog_flags anyways. Having XDP_SETUP_PROG vs XDP_SETUP_PROG_HW should be enough of an indicator of what is required of driver to correctly reset active BPF program. dev_xdp_uninstall() is also generalized as an iteration over all three supported mode. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200722064603.3350758-3-andriin@fb.com --- include/linux/netdevice.h | 17 ++++- net/core/dev.c | 158 ++++++++++++++++++++++++++-------------------- net/core/rtnetlink.c | 5 +- 3 files changed, 105 insertions(+), 75 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index ac2cd3f49aba..cad44b40c776 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -889,6 +889,17 @@ struct netlink_ext_ack; struct xdp_umem; struct xdp_dev_bulk_queue; +enum bpf_xdp_mode { + XDP_MODE_SKB = 0, + XDP_MODE_DRV = 1, + XDP_MODE_HW = 2, + __MAX_XDP_MODE +}; + +struct bpf_xdp_entity { + struct bpf_prog *prog; +}; + struct netdev_bpf { enum bpf_netdev_command command; union { @@ -2142,6 +2153,9 @@ struct net_device { #endif const struct udp_tunnel_nic_info *udp_tunnel_nic_info; struct udp_tunnel_nic *udp_tunnel_nic; + + /* protected by rtnl_lock */ + struct bpf_xdp_entity xdp_state[__MAX_XDP_MODE]; }; #define to_net_dev(d) container_of(d, struct net_device, dev) @@ -3817,8 +3831,7 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf); int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, int fd, int expected_fd, u32 flags); -u32 __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op, - enum bpf_netdev_command cmd); +u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode); int xdp_umem_query(struct net_device *dev, u16 queue_id); int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb); diff --git a/net/core/dev.c b/net/core/dev.c index fe2e387eed29..bf38fde667e9 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8716,84 +8716,103 @@ int dev_change_proto_down_generic(struct net_device *dev, bool proto_down) } EXPORT_SYMBOL(dev_change_proto_down_generic); -u32 __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op, - enum bpf_netdev_command cmd) +static enum bpf_xdp_mode dev_xdp_mode(u32 flags) { - struct netdev_bpf xdp; + if (flags & XDP_FLAGS_HW_MODE) + return XDP_MODE_HW; + if (flags & XDP_FLAGS_DRV_MODE) + return XDP_MODE_DRV; + return XDP_MODE_SKB; +} - if (!bpf_op) - return 0; +static bpf_op_t dev_xdp_bpf_op(struct net_device *dev, enum bpf_xdp_mode mode) +{ + switch (mode) { + case XDP_MODE_SKB: + return generic_xdp_install; + case XDP_MODE_DRV: + case XDP_MODE_HW: + return dev->netdev_ops->ndo_bpf; + default: + return NULL; + }; +} - memset(&xdp, 0, sizeof(xdp)); - xdp.command = cmd; +static struct bpf_prog *dev_xdp_prog(struct net_device *dev, + enum bpf_xdp_mode mode) +{ + return dev->xdp_state[mode].prog; +} + +u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode) +{ + struct bpf_prog *prog = dev_xdp_prog(dev, mode); - /* Query must always succeed. */ - WARN_ON(bpf_op(dev, &xdp) < 0 && cmd == XDP_QUERY_PROG); + return prog ? prog->aux->id : 0; +} - return xdp.prog_id; +static void dev_xdp_set_prog(struct net_device *dev, enum bpf_xdp_mode mode, + struct bpf_prog *prog) +{ + dev->xdp_state[mode].prog = prog; } -static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op, - struct netlink_ext_ack *extack, u32 flags, - struct bpf_prog *prog) +static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode, + bpf_op_t bpf_op, struct netlink_ext_ack *extack, + u32 flags, struct bpf_prog *prog) { - bool non_hw = !(flags & XDP_FLAGS_HW_MODE); - struct bpf_prog *prev_prog = NULL; struct netdev_bpf xdp; int err; - if (non_hw) { - prev_prog = bpf_prog_by_id(__dev_xdp_query(dev, bpf_op, - XDP_QUERY_PROG)); - if (IS_ERR(prev_prog)) - prev_prog = NULL; - } - memset(&xdp, 0, sizeof(xdp)); - if (flags & XDP_FLAGS_HW_MODE) - xdp.command = XDP_SETUP_PROG_HW; - else - xdp.command = XDP_SETUP_PROG; + xdp.command = mode == XDP_MODE_HW ? XDP_SETUP_PROG_HW : XDP_SETUP_PROG; xdp.extack = extack; xdp.flags = flags; xdp.prog = prog; + /* Drivers assume refcnt is already incremented (i.e, prog pointer is + * "moved" into driver), so they don't increment it on their own, but + * they do decrement refcnt when program is detached or replaced. + * Given net_device also owns link/prog, we need to bump refcnt here + * to prevent drivers from underflowing it. + */ + if (prog) + bpf_prog_inc(prog); err = bpf_op(dev, &xdp); - if (!err && non_hw) - bpf_prog_change_xdp(prev_prog, prog); + if (err) { + if (prog) + bpf_prog_put(prog); + return err; + } - if (prev_prog) - bpf_prog_put(prev_prog); + if (mode != XDP_MODE_HW) + bpf_prog_change_xdp(dev_xdp_prog(dev, mode), prog); - return err; + return 0; } static void dev_xdp_uninstall(struct net_device *dev) { - struct netdev_bpf xdp; - bpf_op_t ndo_bpf; + struct bpf_prog *prog; + enum bpf_xdp_mode mode; + bpf_op_t bpf_op; - /* Remove generic XDP */ - WARN_ON(dev_xdp_install(dev, generic_xdp_install, NULL, 0, NULL)); + ASSERT_RTNL(); - /* Remove from the driver */ - ndo_bpf = dev->netdev_ops->ndo_bpf; - if (!ndo_bpf) - return; + for (mode = XDP_MODE_SKB; mode < __MAX_XDP_MODE; mode++) { + prog = dev_xdp_prog(dev, mode); + if (!prog) + continue; - memset(&xdp, 0, sizeof(xdp)); - xdp.command = XDP_QUERY_PROG; - WARN_ON(ndo_bpf(dev, &xdp)); - if (xdp.prog_id) - WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags, - NULL)); + bpf_op = dev_xdp_bpf_op(dev, mode); + if (!bpf_op) + continue; - /* Remove HW offload */ - memset(&xdp, 0, sizeof(xdp)); - xdp.command = XDP_QUERY_PROG_HW; - if (!ndo_bpf(dev, &xdp) && xdp.prog_id) - WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags, - NULL)); + WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL)); + + bpf_prog_put(prog); + dev_xdp_set_prog(dev, mode, NULL); + } } /** @@ -8810,29 +8829,22 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, int fd, int expected_fd, u32 flags) { const struct net_device_ops *ops = dev->netdev_ops; - enum bpf_netdev_command query; + enum bpf_xdp_mode mode = dev_xdp_mode(flags); + bool offload = mode == XDP_MODE_HW; u32 prog_id, expected_id = 0; - bpf_op_t bpf_op, bpf_chk; struct bpf_prog *prog; - bool offload; + bpf_op_t bpf_op; int err; ASSERT_RTNL(); - offload = flags & XDP_FLAGS_HW_MODE; - query = offload ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG; - - bpf_op = bpf_chk = ops->ndo_bpf; - if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) { + 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; } - if (!bpf_op || (flags & XDP_FLAGS_SKB_MODE)) - bpf_op = generic_xdp_install; - if (bpf_op == bpf_chk) - bpf_chk = generic_xdp_install; - prog_id = __dev_xdp_query(dev, bpf_op, query); + 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, @@ -8850,8 +8862,11 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, } } if (fd >= 0) { - if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) { - NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time"); + 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)) { + NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time"); return -EEXIST; } @@ -8866,7 +8881,7 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, return PTR_ERR(prog); if (!offload && bpf_prog_is_dev_bound(prog->aux)) { - NL_SET_ERR_MSG(extack, "using device-bound program without HW_MODE flag is not supported"); + NL_SET_ERR_MSG(extack, "Using device-bound program without HW_MODE flag is not supported"); bpf_prog_put(prog); return -EINVAL; } @@ -8895,11 +8910,14 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, prog = NULL; } - err = dev_xdp_install(dev, bpf_op, extack, flags, prog); - if (err < 0 && prog) + err = dev_xdp_install(dev, mode, bpf_op, extack, flags, prog); + if (err < 0 && prog) { bpf_prog_put(prog); + return err; + } + dev_xdp_set_prog(dev, mode, prog); - return err; + return 0; } /** diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 85a4b0101f76..58c484a28395 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1416,13 +1416,12 @@ static u32 rtnl_xdp_prog_skb(struct net_device *dev) static u32 rtnl_xdp_prog_drv(struct net_device *dev) { - return __dev_xdp_query(dev, dev->netdev_ops->ndo_bpf, XDP_QUERY_PROG); + return dev_xdp_prog_id(dev, XDP_MODE_DRV); } static u32 rtnl_xdp_prog_hw(struct net_device *dev) { - return __dev_xdp_query(dev, dev->netdev_ops->ndo_bpf, - XDP_QUERY_PROG_HW); + return dev_xdp_prog_id(dev, XDP_MODE_HW); } static int rtnl_xdp_report_one(struct sk_buff *skb, struct net_device *dev, -- 2.11.0