diff options
author | Jesper Dangaard Brouer <brouer@redhat.com> | 2017-09-10 10:47:02 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-09-12 00:33:00 +0300 |
commit | 96c5508e3012ed0984ab93821d64ac1ff3279c09 (patch) | |
tree | 89cbc7aab1d9bfad94ccf2b7eff028cc09b36220 /net/core/filter.c | |
parent | 609320c8a22715b74b39796930c3542719f8ab62 (diff) | |
download | linux-96c5508e3012ed0984ab93821d64ac1ff3279c09.tar.xz |
xdp: implement xdp_redirect_map for generic XDP
Using bpf_redirect_map is allowed for generic XDP programs, but the
appropriate map lookup was never performed in xdp_do_generic_redirect().
Instead the map-index is directly used as the ifindex. For the
xdp_redirect_map sample in SKB-mode '-S', this resulted in trying
sending on ifindex 0 which isn't valid, resulting in getting SKB
packets dropped. Thus, the reported performance numbers are wrong in
commit 24251c264798 ("samples/bpf: add option for native and skb mode
for redirect apps") for the 'xdp_redirect_map -S' case.
Before commit 109980b894e9 ("bpf: don't select potentially stale
ri->map from buggy xdp progs") it could crash the kernel. Like this
commit also check that the map_owner owner is correct before
dereferencing the map pointer. But make sure that this API misusage
can be caught by a tracepoint. Thus, allowing userspace via
tracepoints to detect misbehaving bpf_progs.
Fixes: 6103aa96ec07 ("net: implement XDP_REDIRECT for xdp generic")
Fixes: 24251c264798 ("samples/bpf: add option for native and skb mode for redirect apps")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/filter.c')
-rw-r--r-- | net/core/filter.c | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 3a50a9b021e2..24dd33dd9f04 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2506,21 +2506,19 @@ static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp, struct redirect_info *ri = this_cpu_ptr(&redirect_info); const struct bpf_prog *map_owner = ri->map_owner; struct bpf_map *map = ri->map; + struct net_device *fwd = NULL; u32 index = ri->ifindex; - struct net_device *fwd; int err; ri->ifindex = 0; ri->map = NULL; ri->map_owner = NULL; - /* This is really only caused by a deliberately crappy - * BPF program, normally we would never hit that case, - * so no need to inform someone via tracepoints either, - * just bail out. - */ - if (unlikely(map_owner != xdp_prog)) - return -EINVAL; + if (unlikely(map_owner != xdp_prog)) { + err = -EFAULT; + map = NULL; + goto err; + } fwd = __dev_map_lookup_elem(map, index); if (!fwd) { @@ -2576,13 +2574,27 @@ int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb, struct bpf_prog *xdp_prog) { struct redirect_info *ri = this_cpu_ptr(&redirect_info); + const struct bpf_prog *map_owner = ri->map_owner; + struct bpf_map *map = ri->map; + struct net_device *fwd = NULL; u32 index = ri->ifindex; - struct net_device *fwd; unsigned int len; int err = 0; - fwd = dev_get_by_index_rcu(dev_net(dev), index); ri->ifindex = 0; + ri->map = NULL; + ri->map_owner = NULL; + + if (map) { + if (unlikely(map_owner != xdp_prog)) { + err = -EFAULT; + map = NULL; + goto err; + } + fwd = __dev_map_lookup_elem(map, index); + } else { + fwd = dev_get_by_index_rcu(dev_net(dev), index); + } if (unlikely(!fwd)) { err = -EINVAL; goto err; @@ -2600,10 +2612,12 @@ int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb, } skb->dev = fwd; - _trace_xdp_redirect(dev, xdp_prog, index); + map ? _trace_xdp_redirect_map(dev, xdp_prog, fwd, map, index) + : _trace_xdp_redirect(dev, xdp_prog, index); return 0; err: - _trace_xdp_redirect_err(dev, xdp_prog, index, err); + map ? _trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map, index, err) + : _trace_xdp_redirect_err(dev, xdp_prog, index, err); return err; } EXPORT_SYMBOL_GPL(xdp_do_generic_redirect); |