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authorBjörn Töpel <bjorn.topel@intel.com>2021-03-08 12:29:07 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2021-03-10 01:06:34 +0100
commitee75aef23afe6e88497151c127c13ed69f41aaa2 (patch)
tree2e6ca2aa0d6d1ac694002dd4aff11915473d4118
parente6a4750ffe9d701c4d55212b14b615e63571d235 (diff)
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.h10
-rw-r--r--include/trace/events/xdp.h62
-rw-r--r--kernel/bpf/cpumap.c1
-rw-r--r--kernel/bpf/devmap.c1
-rw-r--r--net/core/filter.c170
-rw-r--r--net/xdp/xskmap.c1
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);
}