AF_XDP bind currently accepts zero-copy pool configurations without verifying that the device MTU fits into the usable frame space provided by the UMEM chunk. This becomes a problem since we started to respect tailroom which is subtracted from chunk_size (among with headroom). 2k chunk size might not provide enough space for standard 1500 MTU, so let us catch such settings at bind time. This prevents creating an already-invalid setup and complements the MTU change restriction for devices with an attached XSK pool. Currently xp_assign_dev_shared() is missing XDP_USE_SG being propagated to flags so set it in order to preserve mtu check that is supposed to be done only when no multi-buffer setup is in picture. Signed-off-by: Maciej Fijalkowski --- net/xdp/xsk_buff_pool.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c index 37b7a68b89b3..e9377b05118b 100644 --- a/net/xdp/xsk_buff_pool.c +++ b/net/xdp/xsk_buff_pool.c @@ -157,6 +157,7 @@ static void xp_disable_drv_zc(struct xsk_buff_pool *pool) int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev, u16 queue_id, u16 flags) { + bool mbuf = flags & XDP_USE_SG; bool force_zc, force_copy; struct netdev_bpf bpf; int err = 0; @@ -178,7 +179,7 @@ int xp_assign_dev(struct xsk_buff_pool *pool, if (err) return err; - if (flags & XDP_USE_SG) + if (mbuf) pool->umem->flags |= XDP_UMEM_SG_FLAG; if (flags & XDP_USE_NEED_WAKEUP) @@ -200,10 +201,18 @@ int xp_assign_dev(struct xsk_buff_pool *pool, goto err_unreg_pool; } - if (netdev->xdp_zc_max_segs == 1 && (flags & XDP_USE_SG)) { + if (netdev->xdp_zc_max_segs == 1 && mbuf) { err = -EOPNOTSUPP; goto err_unreg_pool; } +#define ETH_PAD_LEN (ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN) + if (!mbuf) { + if (READ_ONCE(netdev->mtu) + ETH_PAD_LEN > + xsk_pool_get_rx_frame_size(pool)) { + err = -EINVAL; + goto err_unreg_pool; + } + } if (dev_get_min_mp_channel_count(netdev)) { err = -EBUSY; @@ -247,6 +256,9 @@ int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_sock *umem_xs, struct xdp_umem *umem = umem_xs->umem; flags = umem->zc ? XDP_ZEROCOPY : XDP_COPY; + if (umem->flags & XDP_UMEM_SG_FLAG) + flags |= XDP_USE_SG; + if (umem_xs->pool->uses_need_wakeup) flags |= XDP_USE_NEED_WAKEUP; -- 2.43.0