Commit 6d5fc195 authored by Toshiaki Makita's avatar Toshiaki Makita Committed by Daniel Borkmann
Browse files

xdp: Fix handling of devmap in generic XDP 



Commit 67f29e07 ("bpf: devmap introduce dev_map_enqueue") changed
the return value type of __devmap_lookup_elem() from struct net_device *
to struct bpf_dtab_netdev * but forgot to modify generic XDP code
accordingly.

Thus generic XDP incorrectly used struct bpf_dtab_netdev where struct
net_device is expected, then skb->dev was set to invalid value.

v2:
- Fix compiler warning without CONFIG_BPF_SYSCALL.

Fixes: 67f29e07 ("bpf: devmap introduce dev_map_enqueue")
Signed-off-by: default avatarToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Acked-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent b5518c70

include/linux/bpf.h

+12 −0
Original line number Diff line number Diff line
@@ -488,12 +488,15 @@ void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth); 


/* Map specifics */

struct xdp_buff;

struct sk_buff;



struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key);

void __dev_map_insert_ctx(struct bpf_map *map, u32 index);

void __dev_map_flush(struct bpf_map *map);

int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,

		    struct net_device *dev_rx);

int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,

			     struct bpf_prog *xdp_prog);



struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);

void __cpu_map_insert_ctx(struct bpf_map *map, u32 index);
@@ -586,6 +589,15 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp, 
	return 0;

}



struct sk_buff;



static inline int dev_map_generic_redirect(struct bpf_dtab_netdev *dst,

					   struct sk_buff *skb,

					   struct bpf_prog *xdp_prog)

{

	return 0;

}



static inline

struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)

{

include/linux/filter.h

+16 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/cryptohash.h>

#include <linux/set_memory.h>

#include <linux/kallsyms.h>

#include <linux/if_vlan.h>



#include <net/sch_generic.h>
@@ -802,6 +803,21 @@ static inline bool bpf_dump_raw_ok(void) 
struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,

				       const struct bpf_insn *patch, u32 len);



static inline int __xdp_generic_ok_fwd_dev(struct sk_buff *skb,

					   struct net_device *fwd)

{

	unsigned int len;



	if (unlikely(!(fwd->flags & IFF_UP)))

		return -ENETDOWN;



	len = fwd->mtu + fwd->hard_header_len + VLAN_HLEN;

	if (skb->len > len)

		return -EMSGSIZE;



	return 0;

}



/* The pair of xdp_do_redirect and xdp_do_flush_map MUST be called in the

 * same cpu context. Further for best results no more than a single map

 * for the do_redirect/do_flush pair should be used. This limitation is

kernel/bpf/devmap.c

+14 −0
Original line number Diff line number Diff line
@@ -345,6 +345,20 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp, 
	return bq_enqueue(dst, xdpf, dev_rx);

}



int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,

			     struct bpf_prog *xdp_prog)

{

	int err;



	err = __xdp_generic_ok_fwd_dev(skb, dst->dev);

	if (unlikely(err))

		return err;

	skb->dev = dst->dev;

	generic_xdp_tx(skb, xdp_prog);



	return 0;

}



static void *dev_map_lookup_elem(struct bpf_map *map, void *key)

{

	struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);

net/core/filter.c

+4 −17
Original line number Diff line number Diff line
@@ -3214,20 +3214,6 @@ err: 
}

EXPORT_SYMBOL_GPL(xdp_do_redirect);



static int __xdp_generic_ok_fwd_dev(struct sk_buff *skb, struct net_device *fwd)

{

	unsigned int len;



	if (unlikely(!(fwd->flags & IFF_UP)))

		return -ENETDOWN;



	len = fwd->mtu + fwd->hard_header_len + VLAN_HLEN;

	if (skb->len > len)

		return -EMSGSIZE;



	return 0;

}



static int xdp_do_generic_redirect_map(struct net_device *dev,

				       struct sk_buff *skb,

				       struct xdp_buff *xdp,
@@ -3256,10 +3242,11 @@ static int xdp_do_generic_redirect_map(struct net_device *dev, 
	}



	if (map->map_type == BPF_MAP_TYPE_DEVMAP) {

		if (unlikely((err = __xdp_generic_ok_fwd_dev(skb, fwd))))

		struct bpf_dtab_netdev *dst = fwd;



		err = dev_map_generic_redirect(dst, skb, xdp_prog);

		if (unlikely(err))

			goto err;

		skb->dev = fwd;

		generic_xdp_tx(skb, xdp_prog);

	} else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {

		struct xdp_sock *xs = fwd;

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