diff options
| author |   Jesper Dangaard Brouer <brouer@redhat.com> | 2020-05-14 12:51:25 +0200 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2020-05-14 21:21:56 -0700 |
| commit | c8741e2bfe872425ea6f10bb6f7dc1d67bc60c3a (patch) | |
| tree | f03ab9412cde9c6a8076e9f1b83e6fe1aae17058 | |
| parent | mlx5: Rx queue setup time determine frame_sz for XDP (diff) | |
| download | wireguard-linux-c8741e2bfe872425ea6f10bb6f7dc1d67bc60c3a.tar.xz wireguard-linux-c8741e2bfe872425ea6f10bb6f7dc1d67bc60c3a.zip | |
xdp: Allow bpf_xdp_adjust_tail() to grow packet size
Finally, after all drivers have a frame size, allow BPF-helper
bpf_xdp_adjust_tail() to grow or extend packet size at frame tail.
Remember that helper/macro xdp_data_hard_end have reserved some
tailroom. Thus, this helper makes sure that the BPF-prog don't have
access to this tailroom area.
V2: Remove one chicken check and use WARN_ONCE for other
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158945348530.97035.12577148209134239291.stgit@firesoul
| -rw-r--r-- | include/uapi/linux/bpf.h | 4 | ||||
| -rw-r--r-- | net/core/filter.c | 11 |
2 files changed, 11 insertions, 4 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 32cbf36c7729..b9b8a0f63b91 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2015,8 +2015,8 @@ union bpf_attr { * int bpf_xdp_adjust_tail(struct xdp_buff *xdp_md, int delta) * Description * Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is - * only possible to shrink the packet as of this writing, - * therefore *delta* must be a negative integer. + * possible to both shrink and grow the packet tail. + * Shrink done via *delta* being a negative integer. * * A call to this helper is susceptible to change the underlying * packet buffer. Therefore, at load time, all checks on pointers diff --git a/net/core/filter.c b/net/core/filter.c index 5815902bb617..e7b033dad44e 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3411,12 +3411,19 @@ static const struct bpf_func_proto bpf_xdp_adjust_head_proto = { BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset) { + void *data_hard_end = xdp_data_hard_end(xdp); /* use xdp->frame_sz */ void *data_end = xdp->data_end + offset; - /* only shrinking is allowed for now. */ - if (unlikely(offset >= 0)) + /* Notice that xdp_data_hard_end have reserved some tailroom */ + if (unlikely(data_end > data_hard_end)) return -EINVAL; + /* ALL drivers MUST init xdp->frame_sz, chicken check below */ + if (unlikely(xdp->frame_sz > PAGE_SIZE)) { + WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz); + return -EINVAL; + } + if (unlikely(data_end < xdp->data + ETH_HLEN)) return -EINVAL; |