From 47f999a8d0fc856696c4b91d2d90682483f494b7 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 2 Jul 2021 16:48:21 +0530 Subject: [PATCH] net: core: Split out code to run generic XDP prog MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This helper can later be utilized in code that runs cpumap and devmap programs in generic redirect mode and adjust skb based on changes made to xdp_buff. When returning XDP_REDIRECT/XDP_TX, it invokes __skb_push, so whenever a generic redirect path invokes devmap/cpumap prog if set, it must __skb_pull again as we expect mac header to be pulled. It also drops the skb_reset_mac_len call after do_xdp_generic, as the mac_header and network_header are advanced by the same offset, so the difference (mac_len) remains constant. Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Reviewed-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210702111825.491065-2-memxor@gmail.com --- include/linux/netdevice.h | 2 + net/core/dev.c | 84 ++++++++++++++++++++++++--------------- 2 files changed, 55 insertions(+), 31 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index eaf5bb008aa99..42f6f866d5f39 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3984,6 +3984,8 @@ static inline void dev_consume_skb_any(struct sk_buff *skb) __dev_kfree_skb_any(skb, SKB_REASON_CONSUMED); } +u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp, + struct bpf_prog *xdp_prog); void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog); int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb); int netif_rx(struct sk_buff *skb); diff --git a/net/core/dev.c b/net/core/dev.c index c253c2aafe97c..93e80c36cc972 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4744,45 +4744,18 @@ static struct netdev_rx_queue *netif_get_rxqueue(struct sk_buff *skb) return rxqueue; } -static u32 netif_receive_generic_xdp(struct sk_buff *skb, - struct xdp_buff *xdp, - struct bpf_prog *xdp_prog) +u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp, + struct bpf_prog *xdp_prog) { void *orig_data, *orig_data_end, *hard_start; struct netdev_rx_queue *rxqueue; - u32 metalen, act = XDP_DROP; bool orig_bcast, orig_host; u32 mac_len, frame_sz; __be16 orig_eth_type; struct ethhdr *eth; + u32 metalen, act; int off; - /* Reinjected packets coming from act_mirred or similar should - * not get XDP generic processing. - */ - if (skb_is_redirected(skb)) - return XDP_PASS; - - /* XDP packets must be linear and must have sufficient headroom - * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also - * native XDP provides, thus we need to do it here as well. - */ - if (skb_cloned(skb) || skb_is_nonlinear(skb) || - skb_headroom(skb) < XDP_PACKET_HEADROOM) { - int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb); - int troom = skb->tail + skb->data_len - skb->end; - - /* In case we have to go down the path and also linearize, - * then lets do the pskb_expand_head() work just once here. - */ - if (pskb_expand_head(skb, - hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0, - troom > 0 ? troom + 128 : 0, GFP_ATOMIC)) - goto do_drop; - if (skb_linearize(skb)) - goto do_drop; - } - /* The XDP program wants to see the packet starting at the MAC * header. */ @@ -4837,6 +4810,13 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, skb->protocol = eth_type_trans(skb, skb->dev); } + /* Redirect/Tx gives L2 packet, code that will reuse skb must __skb_pull + * before calling us again on redirect path. We do not call do_redirect + * as we leave that up to the caller. + * + * Caller is responsible for managing lifetime of skb (i.e. calling + * kfree_skb in response to actions it cannot handle/XDP_DROP). + */ switch (act) { case XDP_REDIRECT: case XDP_TX: @@ -4847,6 +4827,49 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, if (metalen) skb_metadata_set(skb, metalen); break; + } + + return act; +} + +static u32 netif_receive_generic_xdp(struct sk_buff *skb, + struct xdp_buff *xdp, + struct bpf_prog *xdp_prog) +{ + u32 act = XDP_DROP; + + /* Reinjected packets coming from act_mirred or similar should + * not get XDP generic processing. + */ + if (skb_is_redirected(skb)) + return XDP_PASS; + + /* XDP packets must be linear and must have sufficient headroom + * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also + * native XDP provides, thus we need to do it here as well. + */ + if (skb_cloned(skb) || skb_is_nonlinear(skb) || + skb_headroom(skb) < XDP_PACKET_HEADROOM) { + int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb); + int troom = skb->tail + skb->data_len - skb->end; + + /* In case we have to go down the path and also linearize, + * then lets do the pskb_expand_head() work just once here. + */ + if (pskb_expand_head(skb, + hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0, + troom > 0 ? troom + 128 : 0, GFP_ATOMIC)) + goto do_drop; + if (skb_linearize(skb)) + goto do_drop; + } + + act = bpf_prog_run_generic_xdp(skb, xdp, xdp_prog); + switch (act) { + case XDP_REDIRECT: + case XDP_TX: + case XDP_PASS: + break; default: bpf_warn_invalid_xdp_action(act); fallthrough; @@ -5312,7 +5335,6 @@ another_round: ret = NET_RX_DROP; goto out; } - skb_reset_mac_len(skb); } if (eth_type_vlan(skb->protocol)) { -- 2.39.5