From ee75aef23afe6e88497151c127c13ed69f41aaa2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Mon, 8 Mar 2021 12:29:07 +0100 Subject: bpf, xdp: Restructure redirect actions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The XDP_REDIRECT implementations for maps and non-maps are fairly similar, but obviously need to take different code paths depending on if the target is using a map or not. Today, the redirect targets for XDP either uses a map, or is based on ifindex. Here, the map type and id are added to bpf_redirect_info, instead of the actual map. Map type, map item/ifindex, and the map_id (if any) is passed to xdp_do_redirect(). For ifindex-based redirect, used by the bpf_redirect() XDP BFP helper, a special map type/id are used. Map type of UNSPEC together with map id equal to INT_MAX has the special meaning of an ifindex based redirect. Note that valid map ids are 1 inclusive, INT_MAX exclusive ([1,INT_MAX[). In addition to making the code easier to follow, using explicit type and id in bpf_redirect_info has a slight positive performance impact by avoiding a pointer indirection for the map type lookup, and instead use the cacheline for bpf_redirect_info. Since the actual map is not passed via bpf_redirect_info anymore, the map lookup is only done in the BPF helper. This means that the bpf_clear_redirect_map() function can be removed. The actual map item is RCU protected. The bpf_redirect_info flags member is not used by XDP, and not read/written any more. The map member is only written to when required/used, and not unconditionally. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Reviewed-by: Maciej Fijalkowski Acked-by: Jesper Dangaard Brouer Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com --- net/core/filter.c | 170 ++++++++++++++++++++++++------------------------------ net/xdp/xskmap.c | 1 - 2 files changed, 75 insertions(+), 96 deletions(-) (limited to 'net') diff --git a/net/core/filter.c b/net/core/filter.c index 183b0aa6b027..b6732000d8a2 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3918,23 +3918,6 @@ static const struct bpf_func_proto bpf_xdp_adjust_meta_proto = { .arg2_type = ARG_ANYTHING, }; -static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd, - struct bpf_map *map, struct xdp_buff *xdp) -{ - switch (map->map_type) { - case BPF_MAP_TYPE_DEVMAP: - case BPF_MAP_TYPE_DEVMAP_HASH: - return dev_map_enqueue(fwd, xdp, dev_rx); - case BPF_MAP_TYPE_CPUMAP: - return cpu_map_enqueue(fwd, xdp, dev_rx); - case BPF_MAP_TYPE_XSKMAP: - return __xsk_map_redirect(fwd, xdp); - default: - return -EBADRQC; - } - return 0; -} - void xdp_do_flush(void) { __dev_flush(); @@ -3943,55 +3926,52 @@ void xdp_do_flush(void) } EXPORT_SYMBOL_GPL(xdp_do_flush); -void bpf_clear_redirect_map(struct bpf_map *map) -{ - struct bpf_redirect_info *ri; - int cpu; - - for_each_possible_cpu(cpu) { - ri = per_cpu_ptr(&bpf_redirect_info, cpu); - /* Avoid polluting remote cacheline due to writes if - * not needed. Once we pass this test, we need the - * cmpxchg() to make sure it hasn't been changed in - * the meantime by remote CPU. - */ - if (unlikely(READ_ONCE(ri->map) == map)) - cmpxchg(&ri->map, map, NULL); - } -} - int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp, struct bpf_prog *xdp_prog) { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); - struct bpf_map *map = READ_ONCE(ri->map); - u32 index = ri->tgt_index; + enum bpf_map_type map_type = ri->map_type; void *fwd = ri->tgt_value; + u32 map_id = ri->map_id; int err; - ri->tgt_index = 0; - ri->tgt_value = NULL; - WRITE_ONCE(ri->map, NULL); + ri->map_id = 0; /* Valid map id idr range: [1,INT_MAX[ */ + ri->map_type = BPF_MAP_TYPE_UNSPEC; - if (unlikely(!map)) { - fwd = dev_get_by_index_rcu(dev_net(dev), index); - if (unlikely(!fwd)) { - err = -EINVAL; - goto err; + switch (map_type) { + case BPF_MAP_TYPE_DEVMAP: + fallthrough; + case BPF_MAP_TYPE_DEVMAP_HASH: + err = dev_map_enqueue(fwd, xdp, dev); + break; + case BPF_MAP_TYPE_CPUMAP: + err = cpu_map_enqueue(fwd, xdp, dev); + break; + case BPF_MAP_TYPE_XSKMAP: + err = __xsk_map_redirect(fwd, xdp); + break; + case BPF_MAP_TYPE_UNSPEC: + if (map_id == INT_MAX) { + fwd = dev_get_by_index_rcu(dev_net(dev), ri->tgt_index); + if (unlikely(!fwd)) { + err = -EINVAL; + break; + } + err = dev_xdp_enqueue(fwd, xdp, dev); + break; } - - err = dev_xdp_enqueue(fwd, xdp, dev); - } else { - err = __bpf_tx_xdp_map(dev, fwd, map, xdp); + fallthrough; + default: + err = -EBADRQC; } if (unlikely(err)) goto err; - _trace_xdp_redirect_map(dev, xdp_prog, fwd, map, index); + _trace_xdp_redirect_map(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index); return 0; err: - _trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map, index, err); + _trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index, err); return err; } EXPORT_SYMBOL_GPL(xdp_do_redirect); @@ -4000,41 +3980,36 @@ static int xdp_do_generic_redirect_map(struct net_device *dev, struct sk_buff *skb, struct xdp_buff *xdp, struct bpf_prog *xdp_prog, - struct bpf_map *map) + void *fwd, + enum bpf_map_type map_type, u32 map_id) { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); - u32 index = ri->tgt_index; - void *fwd = ri->tgt_value; - int err = 0; - - ri->tgt_index = 0; - ri->tgt_value = NULL; - WRITE_ONCE(ri->map, NULL); - - if (map->map_type == BPF_MAP_TYPE_DEVMAP || - map->map_type == BPF_MAP_TYPE_DEVMAP_HASH) { - struct bpf_dtab_netdev *dst = fwd; + int err; - err = dev_map_generic_redirect(dst, skb, xdp_prog); + switch (map_type) { + case BPF_MAP_TYPE_DEVMAP: + fallthrough; + case BPF_MAP_TYPE_DEVMAP_HASH: + err = dev_map_generic_redirect(fwd, skb, xdp_prog); if (unlikely(err)) goto err; - } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) { - struct xdp_sock *xs = fwd; - - err = xsk_generic_rcv(xs, xdp); + break; + case BPF_MAP_TYPE_XSKMAP: + err = xsk_generic_rcv(fwd, xdp); if (err) goto err; consume_skb(skb); - } else { + break; + default: /* TODO: Handle BPF_MAP_TYPE_CPUMAP */ err = -EBADRQC; goto err; } - _trace_xdp_redirect_map(dev, xdp_prog, fwd, map, index); + _trace_xdp_redirect_map(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index); return 0; err: - _trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map, index, err); + _trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index, err); return err; } @@ -4042,31 +4017,34 @@ int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb, struct xdp_buff *xdp, struct bpf_prog *xdp_prog) { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); - struct bpf_map *map = READ_ONCE(ri->map); - u32 index = ri->tgt_index; - struct net_device *fwd; - int err = 0; - - if (map) - return xdp_do_generic_redirect_map(dev, skb, xdp, xdp_prog, - map); - ri->tgt_index = 0; - fwd = dev_get_by_index_rcu(dev_net(dev), index); - if (unlikely(!fwd)) { - err = -EINVAL; - goto err; - } + enum bpf_map_type map_type = ri->map_type; + void *fwd = ri->tgt_value; + u32 map_id = ri->map_id; + int err; - err = xdp_ok_fwd_dev(fwd, skb->len); - if (unlikely(err)) - goto err; + ri->map_id = 0; /* Valid map id idr range: [1,INT_MAX[ */ + ri->map_type = BPF_MAP_TYPE_UNSPEC; - skb->dev = fwd; - _trace_xdp_redirect(dev, xdp_prog, index); - generic_xdp_tx(skb, xdp_prog); - return 0; + if (map_type == BPF_MAP_TYPE_UNSPEC && map_id == INT_MAX) { + fwd = dev_get_by_index_rcu(dev_net(dev), ri->tgt_index); + if (unlikely(!fwd)) { + err = -EINVAL; + goto err; + } + + err = xdp_ok_fwd_dev(fwd, skb->len); + if (unlikely(err)) + goto err; + + skb->dev = fwd; + _trace_xdp_redirect(dev, xdp_prog, ri->tgt_index); + generic_xdp_tx(skb, xdp_prog); + return 0; + } + + return xdp_do_generic_redirect_map(dev, skb, xdp, xdp_prog, fwd, map_type, map_id); err: - _trace_xdp_redirect_err(dev, xdp_prog, index, err); + _trace_xdp_redirect_err(dev, xdp_prog, ri->tgt_index, err); return err; } @@ -4077,10 +4055,12 @@ BPF_CALL_2(bpf_xdp_redirect, u32, ifindex, u64, flags) if (unlikely(flags)) return XDP_ABORTED; - ri->flags = flags; + /* NB! Map type UNSPEC and map_id == INT_MAX (never generated + * by map_idr) is used for ifindex based XDP redirect. + */ ri->tgt_index = ifindex; - ri->tgt_value = NULL; - WRITE_ONCE(ri->map, NULL); + ri->map_id = INT_MAX; + ri->map_type = BPF_MAP_TYPE_UNSPEC; return XDP_REDIRECT; } diff --git a/net/xdp/xskmap.c b/net/xdp/xskmap.c index fbeb4870f798..67b4ce504852 100644 --- a/net/xdp/xskmap.c +++ b/net/xdp/xskmap.c @@ -87,7 +87,6 @@ static void xsk_map_free(struct bpf_map *map) { struct xsk_map *m = container_of(map, struct xsk_map, map); - bpf_clear_redirect_map(map); synchronize_net(); bpf_map_area_free(m); } -- cgit v1.2.3