diff options
| -rw-r--r-- | include/linux/filter.h | 1 | ||||
| -rw-r--r-- | include/trace/events/xdp.h | 5 | ||||
| -rw-r--r-- | include/uapi/linux/bpf.h | 7 | ||||
| -rw-r--r-- | net/core/filter.c | 32 |
4 files changed, 26 insertions, 19 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index 92bd192f7786..1fe53e78c7e3 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -580,6 +580,7 @@ struct bpf_skb_data_end { struct bpf_redirect_info { u32 flags; u32 tgt_index; + void *tgt_value; struct bpf_map *map; struct bpf_map *map_to_flush; u32 kern_flags; diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h index 81e708c4b513..68899fdc985b 100644 --- a/include/trace/events/xdp.h +++ b/include/trace/events/xdp.h @@ -175,9 +175,8 @@ struct _bpf_dtab_netdev { #endif /* __DEVMAP_OBJ_TYPE */ #define devmap_ifindex(fwd, map) \ - (!fwd ? 0 : \ - ((map->map_type == BPF_MAP_TYPE_DEVMAP) ? \ - ((struct _bpf_dtab_netdev *)fwd)->dev->ifindex : 0)) + ((map->map_type == BPF_MAP_TYPE_DEVMAP) ? \ + ((struct _bpf_dtab_netdev *)fwd)->dev->ifindex : 0) #define _trace_xdp_redirect_map(dev, xdp, fwd, map, idx) \ trace_xdp_redirect_map(dev, xdp, devmap_ifindex(fwd, map), \ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index a396b516a2b2..cffea1826a1f 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1571,8 +1571,11 @@ union bpf_attr { * but this is only implemented for native XDP (with driver * support) as of this writing). * - * All values for *flags* are reserved for future usage, and must - * be left at zero. + * The lower two bits of *flags* are used as the return code if + * the map lookup fails. This is so that the return value can be + * one of the XDP program return codes up to XDP_TX, as chosen by + * the caller. Any higher bits in the *flags* argument must be + * unset. * * When used to redirect packets to net devices, this helper * provides a high performance increase over **bpf_redirect**\ (). diff --git a/net/core/filter.c b/net/core/filter.c index b4a062379bb9..4836264f82ee 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3605,17 +3605,13 @@ static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp, struct bpf_redirect_info *ri) { u32 index = ri->tgt_index; - void *fwd = NULL; + void *fwd = ri->tgt_value; int err; ri->tgt_index = 0; + ri->tgt_value = NULL; WRITE_ONCE(ri->map, NULL); - fwd = __xdp_map_lookup_elem(map, index); - if (unlikely(!fwd)) { - err = -EINVAL; - goto err; - } if (ri->map_to_flush && unlikely(ri->map_to_flush != map)) xdp_do_flush_map(); @@ -3652,18 +3648,13 @@ static int xdp_do_generic_redirect_map(struct net_device *dev, { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); u32 index = ri->tgt_index; - void *fwd = NULL; + void *fwd = ri->tgt_value; int err = 0; ri->tgt_index = 0; + ri->tgt_value = NULL; WRITE_ONCE(ri->map, NULL); - fwd = __xdp_map_lookup_elem(map, index); - if (unlikely(!fwd)) { - err = -EINVAL; - goto err; - } - if (map->map_type == BPF_MAP_TYPE_DEVMAP) { struct bpf_dtab_netdev *dst = fwd; @@ -3732,6 +3723,7 @@ BPF_CALL_2(bpf_xdp_redirect, u32, ifindex, u64, flags) ri->flags = flags; ri->tgt_index = ifindex; + ri->tgt_value = NULL; WRITE_ONCE(ri->map, NULL); return XDP_REDIRECT; @@ -3750,9 +3742,21 @@ BPF_CALL_3(bpf_xdp_redirect_map, struct bpf_map *, map, u32, ifindex, { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); - if (unlikely(flags)) + /* Lower bits of the flags are used as return code on lookup failure */ + if (unlikely(flags > XDP_TX)) return XDP_ABORTED; + ri->tgt_value = __xdp_map_lookup_elem(map, ifindex); + if (unlikely(!ri->tgt_value)) { + /* If the lookup fails we want to clear out the state in the + * redirect_info struct completely, so that if an eBPF program + * performs multiple lookups, the last one always takes + * precedence. + */ + WRITE_ONCE(ri->map, NULL); + return flags; + } + ri->flags = flags; ri->tgt_index = ifindex; WRITE_ONCE(ri->map, map); |