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-rw-r--r--include/linux/filter.h1
-rw-r--r--include/trace/events/xdp.h5
-rw-r--r--include/uapi/linux/bpf.h7
-rw-r--r--net/core/filter.c32
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);