BPF programs can use the devmap with a bpf_redirect_map() helper
routine to forward packets to netdevice in map.
Signed-off-by: John Fastabend <john.fastab...@gmail.com>
Acked-by: Daniel Borkmann <dan...@iogearbox.net>
---
include/linux/bpf.h | 3 +++
include/uapi/linux/bpf.h | 8 ++++++-
kernel/bpf/devmap.c | 12 ++++++++++
kernel/bpf/verifier.c | 4 +++
net/core/filter.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 80 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5175729..8c2f3e1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -374,4 +374,7 @@ static inline void __bpf_prog_uncharge(struct user_struct
*user, u32 pages)
void bpf_user_rnd_init_once(void);
u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
+/* Map specifics */
+struct net_device *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
+
#endif /* _LINUX_BPF_H */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 0a48060..b95f46d 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -346,6 +346,11 @@ enum bpf_attach_type {
* @flags: bit 0 - if set, redirect to ingress instead of egress
* other bits - reserved
* Return: TC_ACT_REDIRECT
+ * int bpf_redirect_map(key, map, flags)
+ * redirect to endpoint in map
+ * @key: index in map to lookup
+ * @map: fd of map to do lookup in
+ * @flags: --
*
* u32 bpf_get_route_realm(skb)
* retrieve a dst's tclassid
@@ -569,7 +574,8 @@ enum bpf_attach_type {
FN(probe_read_str), \
FN(get_socket_cookie), \
FN(get_socket_uid), \
- FN(set_hash),
+ FN(set_hash), \
+ FN(redirect_map),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 1a87835..36dc13de 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -159,6 +159,18 @@ static int dev_map_get_next_key(struct bpf_map *map, void
*key, void *next_key)
return 0;
}
+struct net_device *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ struct bpf_dtab_netdev *dev;
+
+ if (key >= map->max_entries)
+ return NULL;
+
+ dev = READ_ONCE(dtab->netdev_map[key]);
+ return dev ? dev->dev : NULL;
+}
+
/* rcu_read_lock (from syscall and BPF contexts) ensures that if a delete
and/or
* update happens in parallel here a dev_put wont happen until after reading
the
* ifindex.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 06073ba..1d03956 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1330,6 +1330,10 @@ static int check_map_func_compatibility(struct bpf_map
*map, int func_id)
if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
goto error;
break;
+ case BPF_FUNC_redirect_map:
+ if (map->map_type != BPF_MAP_TYPE_DEVMAP)
+ goto error;
+ break;
default:
break;
}
diff --git a/net/core/filter.c b/net/core/filter.c
index 441abbb..482bda8 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1778,6 +1778,7 @@ static int __bpf_redirect(struct sk_buff *skb, struct
net_device *dev,
struct redirect_info {
u32 ifindex;
u32 flags;
+ struct bpf_map *map;
};
static DEFINE_PER_CPU(struct redirect_info, redirect_info);
@@ -1791,6 +1792,7 @@ struct redirect_info {
ri->ifindex = ifindex;
ri->flags = flags;
+ ri->map = NULL;
return TC_ACT_REDIRECT;
}
@@ -1818,6 +1820,29 @@ int skb_do_redirect(struct sk_buff *skb)
.arg2_type = ARG_ANYTHING,
};
+BPF_CALL_3(bpf_redirect_map, struct bpf_map *, map, u32, ifindex, u64, flags)
+{
+ struct redirect_info *ri = this_cpu_ptr(&redirect_info);
+
+ if (unlikely(flags))
+ return XDP_ABORTED;
+
+ ri->ifindex = ifindex;
+ ri->flags = flags;
+ ri->map = map;
+
+ return XDP_REDIRECT;
+}
+
+static const struct bpf_func_proto bpf_redirect_map_proto = {
+ .func = bpf_redirect_map,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_ANYTHING,
+ .arg3_type = ARG_ANYTHING,
+};
+
BPF_CALL_1(bpf_get_cgroup_classid, const struct sk_buff *, skb)
{
return task_get_classid(skb);
@@ -2309,14 +2334,41 @@ static int __bpf_tx_xdp(struct net_device *dev, struct
xdp_buff *xdp)
return -EOPNOTSUPP;
}
+int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp,
+ struct bpf_prog *xdp_prog)
+{
+ struct redirect_info *ri = this_cpu_ptr(&redirect_info);
+ struct bpf_map *map = ri->map;
+ struct net_device *fwd;
+
+ fwd = __dev_map_lookup_elem(map, ri->ifindex);
+ if (!fwd)
+ goto out;
+
+ ri->ifindex = 0;
+ ri->map = NULL;
+
+ trace_xdp_redirect(dev, fwd, xdp_prog, XDP_REDIRECT);
+
+ return __bpf_tx_xdp(fwd, xdp);
+out:
+ ri->ifindex = 0;
+ ri->map = NULL;
+ return -EINVAL;
+}
+
int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
struct bpf_prog *xdp_prog)
{
struct redirect_info *ri = this_cpu_ptr(&redirect_info);
struct net_device *fwd;
+ if (ri->map)
+ return xdp_do_redirect_map(dev, xdp, xdp_prog);
+
fwd = dev_get_by_index_rcu(dev_net(dev), ri->ifindex);
ri->ifindex = 0;
+ ri->map = NULL;
if (unlikely(!fwd)) {
bpf_warn_invalid_xdp_redirect(ri->ifindex);
return -EINVAL;
@@ -2868,6 +2920,8 @@ static unsigned long bpf_xdp_copy(void *dst_buff, const
void *src_buff,
return &bpf_xdp_adjust_head_proto;
case BPF_FUNC_redirect:
return &bpf_xdp_redirect_proto;
+ case BPF_FUNC_redirect_map:
+ return &bpf_redirect_map_proto;
default:
return bpf_base_func_proto(func_id);
}
