diff options
author | Björn Töpel <bjorn.topel@intel.com> | 2021-03-08 14:29:07 +0300 |
---|---|---|
committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-03-10 03:06:34 +0300 |
commit | ee75aef23afe6e88497151c127c13ed69f41aaa2 (patch) | |
tree | 2e6ca2aa0d6d1ac694002dd4aff11915473d4118 | |
parent | e6a4750ffe9d701c4d55212b14b615e63571d235 (diff) | |
download | linux-ee75aef23afe6e88497151c127c13ed69f41aaa2.tar.xz |
bpf, xdp: Restructure redirect actions
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 <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com
-rw-r--r-- | include/linux/filter.h | 10 | ||||
-rw-r--r-- | include/trace/events/xdp.h | 62 | ||||
-rw-r--r-- | kernel/bpf/cpumap.c | 1 | ||||
-rw-r--r-- | kernel/bpf/devmap.c | 1 | ||||
-rw-r--r-- | net/core/filter.c | 170 | ||||
-rw-r--r-- | net/xdp/xskmap.c | 1 |
6 files changed, 116 insertions, 129 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index 008691fd3b58..b2b85b2cad8e 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -646,7 +646,8 @@ struct bpf_redirect_info { u32 flags; u32 tgt_index; void *tgt_value; - struct bpf_map *map; + u32 map_id; + enum bpf_map_type map_type; u32 kern_flags; struct bpf_nh_params nh; }; @@ -1488,13 +1489,14 @@ static __always_inline int __bpf_xdp_redirect_map(struct bpf_map *map, u32 ifind * performs multiple lookups, the last one always takes * precedence. */ - WRITE_ONCE(ri->map, NULL); + ri->map_id = INT_MAX; /* Valid map id idr range: [1,INT_MAX[ */ + ri->map_type = BPF_MAP_TYPE_UNSPEC; return flags; } - ri->flags = flags; ri->tgt_index = ifindex; - WRITE_ONCE(ri->map, map); + ri->map_id = map->id; + ri->map_type = map->map_type; return XDP_REDIRECT; } diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h index 76a97176ab81..fcad3645a70b 100644 --- a/include/trace/events/xdp.h +++ b/include/trace/events/xdp.h @@ -86,19 +86,15 @@ struct _bpf_dtab_netdev { }; #endif /* __DEVMAP_OBJ_TYPE */ -#define devmap_ifindex(tgt, map) \ - (((map->map_type == BPF_MAP_TYPE_DEVMAP || \ - map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)) ? \ - ((struct _bpf_dtab_netdev *)tgt)->dev->ifindex : 0) - DECLARE_EVENT_CLASS(xdp_redirect_template, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, const void *tgt, int err, - const struct bpf_map *map, u32 index), + enum bpf_map_type map_type, + u32 map_id, u32 index), - TP_ARGS(dev, xdp, tgt, err, map, index), + TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index), TP_STRUCT__entry( __field(int, prog_id) @@ -111,14 +107,22 @@ DECLARE_EVENT_CLASS(xdp_redirect_template, ), TP_fast_assign( + u32 ifindex = 0, map_index = index; + + if (map_type == BPF_MAP_TYPE_DEVMAP || map_type == BPF_MAP_TYPE_DEVMAP_HASH) { + ifindex = ((struct _bpf_dtab_netdev *)tgt)->dev->ifindex; + } else if (map_type == BPF_MAP_TYPE_UNSPEC && map_id == INT_MAX) { + ifindex = index; + map_index = 0; + } + __entry->prog_id = xdp->aux->id; __entry->act = XDP_REDIRECT; __entry->ifindex = dev->ifindex; __entry->err = err; - __entry->to_ifindex = map ? devmap_ifindex(tgt, map) : - index; - __entry->map_id = map ? map->id : 0; - __entry->map_index = map ? index : 0; + __entry->to_ifindex = ifindex; + __entry->map_id = map_id; + __entry->map_index = map_index; ), TP_printk("prog_id=%d action=%s ifindex=%d to_ifindex=%d err=%d" @@ -133,45 +137,49 @@ DEFINE_EVENT(xdp_redirect_template, xdp_redirect, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, const void *tgt, int err, - const struct bpf_map *map, u32 index), - TP_ARGS(dev, xdp, tgt, err, map, index) + enum bpf_map_type map_type, + u32 map_id, u32 index), + TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index) ); DEFINE_EVENT(xdp_redirect_template, xdp_redirect_err, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, const void *tgt, int err, - const struct bpf_map *map, u32 index), - TP_ARGS(dev, xdp, tgt, err, map, index) + enum bpf_map_type map_type, + u32 map_id, u32 index), + TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index) ); -#define _trace_xdp_redirect(dev, xdp, to) \ - trace_xdp_redirect(dev, xdp, NULL, 0, NULL, to) +#define _trace_xdp_redirect(dev, xdp, to) \ + trace_xdp_redirect(dev, xdp, NULL, 0, BPF_MAP_TYPE_UNSPEC, INT_MAX, to) -#define _trace_xdp_redirect_err(dev, xdp, to, err) \ - trace_xdp_redirect_err(dev, xdp, NULL, err, NULL, to) +#define _trace_xdp_redirect_err(dev, xdp, to, err) \ + trace_xdp_redirect_err(dev, xdp, NULL, err, BPF_MAP_TYPE_UNSPEC, INT_MAX, to) -#define _trace_xdp_redirect_map(dev, xdp, to, map, index) \ - trace_xdp_redirect(dev, xdp, to, 0, map, index) +#define _trace_xdp_redirect_map(dev, xdp, to, map_type, map_id, index) \ + trace_xdp_redirect(dev, xdp, to, 0, map_type, map_id, index) -#define _trace_xdp_redirect_map_err(dev, xdp, to, map, index, err) \ - trace_xdp_redirect_err(dev, xdp, to, err, map, index) +#define _trace_xdp_redirect_map_err(dev, xdp, to, map_type, map_id, index, err) \ + trace_xdp_redirect_err(dev, xdp, to, err, map_type, map_id, index) /* not used anymore, but kept around so as not to break old programs */ DEFINE_EVENT(xdp_redirect_template, xdp_redirect_map, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, const void *tgt, int err, - const struct bpf_map *map, u32 index), - TP_ARGS(dev, xdp, tgt, err, map, index) + enum bpf_map_type map_type, + u32 map_id, u32 index), + TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index) ); DEFINE_EVENT(xdp_redirect_template, xdp_redirect_map_err, TP_PROTO(const struct net_device *dev, const struct bpf_prog *xdp, const void *tgt, int err, - const struct bpf_map *map, u32 index), - TP_ARGS(dev, xdp, tgt, err, map, index) + enum bpf_map_type map_type, + u32 map_id, u32 index), + TP_ARGS(dev, xdp, tgt, err, map_type, map_id, index) ); TRACE_EVENT(xdp_cpumap_kthread, diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c index 7352d4160b7f..0cf2791d5099 100644 --- a/kernel/bpf/cpumap.c +++ b/kernel/bpf/cpumap.c @@ -543,7 +543,6 @@ static void cpu_map_free(struct bpf_map *map) * complete. */ - bpf_clear_redirect_map(map); synchronize_rcu(); /* For cpu_map the remote CPUs can still be using the entries diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index f7f42448259f..7a5ad7331c3b 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -197,7 +197,6 @@ static void dev_map_free(struct bpf_map *map) list_del_rcu(&dtab->list); spin_unlock(&dev_map_lock); - bpf_clear_redirect_map(map); synchronize_rcu(); /* Make sure prior __dev_map_entry_free() have completed. */ 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); } |