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xdp: Fix handling of devmap in generic XDP

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Commit 67f29e07e1 ("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: 67f29e07e1 ("bpf: devmap introduce dev_map_enqueue")
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Toshiaki Makita 2018-06-14 11:07:42 +09:00 committed by Daniel Borkmann
parent b5518c7051
commit 6d5fc19579
4 changed files with 46 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
include/linux/bpf.h
View File

@ -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)
{

16
include/linux/filter.h
View File

@ -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

14
kernel/bpf/devmap.c
View File

@ -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);

21
net/core/filter.c
View File

@ -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;