From: Christian Hopps Date: Thu, 14 Nov 2024 07:07:09 +0000 (-0500) Subject: xfrm: iptfs: add reusing received skb for the tunnel egress packet X-Git-Tag: v6.14-rc1~162^2~102^2~2^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3f3339885fb343b7b42d7c34717108ce07da24ae;p=thirdparty%2Fkernel%2Flinux.git xfrm: iptfs: add reusing received skb for the tunnel egress packet Add an optimization of re-using the tunnel outer skb re-transmission of the inner packet to avoid skb allocation and copy. Signed-off-by: Christian Hopps Tested-by: Antony Antony Signed-off-by: Steffen Klassert --- diff --git a/net/xfrm/xfrm_iptfs.c b/net/xfrm/xfrm_iptfs.c index 4af1f7b5818e6..8538fb02ae8aa 100644 --- a/net/xfrm/xfrm_iptfs.c +++ b/net/xfrm/xfrm_iptfs.c @@ -601,12 +601,12 @@ static bool __input_process_payload(struct xfrm_state *x, u32 data, struct list_head *sublist) { u8 hbytes[sizeof(struct ipv6hdr)]; - struct sk_buff *first_skb, *next, *skb; + struct sk_buff *defer, *first_skb, *next, *skb; const unsigned char *old_mac; struct xfrm_iptfs_data *xtfs; struct iphdr *iph; struct net *net; - u32 remaining, iplen, iphlen, tail; + u32 first_iplen, iphlen, iplen, remaining, tail; u32 capturelen; u64 seq; @@ -614,6 +614,7 @@ static bool __input_process_payload(struct xfrm_state *x, u32 data, net = xs_net(x); skb = skbseq->root_skb; first_skb = NULL; + defer = NULL; seq = __esp_seq(skb); @@ -688,23 +689,92 @@ static bool __input_process_payload(struct xfrm_state *x, u32 data, skb_prepare_seq_read(save, data, tail, skbseq); } - if (!first_skb) + if (first_skb) { + skb = NULL; + } else { first_skb = skb; + first_iplen = iplen; + + /* We are going to skip over `data` bytes to reach the + * start of the IP header of `iphlen` len for `iplen` + * inner packet. + */ + + if (skb_has_frag_list(skb)) { + defer = skb; + skb = NULL; + } else if (data + iphlen <= skb_headlen(skb) && + /* make sure our header is 32-bit aligned? */ + /* ((uintptr_t)(skb->data + data) & 0x3) == 0 && */ + skb_tailroom(skb) + tail - data >= iplen) { + /* Reuse the received skb. + * + * We have enough headlen to pull past any + * initial fragment data, leaving at least the + * IP header in the linear buffer space. + * + * For linear buffer space we only require that + * linear buffer space is large enough to + * eventually hold the entire reassembled + * packet (by including tailroom in the check). + * + * For non-linear tailroom is 0 and so we only + * re-use if the entire packet is present + * already. + * + * NOTE: there are many more options for + * sharing, KISS for now. Also, this can produce + * skb's with the IP header unaligned to 32 + * bits. If that ends up being a problem then a + * check should be added to the conditional + * above that the header lies on a 32-bit + * boundary as well. + */ + skb_pull(skb, data); + + /* our range just changed */ + data = 0; + tail = skb->len; + remaining = skb->len; + + skb->protocol = protocol; + skb_mac_header_rebuild(skb); + if (skb->mac_len) + eth_hdr(skb)->h_proto = skb->protocol; + + /* all pointers could be changed now reset walk */ + skb_abort_seq_read(skbseq); + skb_prepare_seq_read(skb, data, tail, skbseq); + } else { + /* We couldn't reuse the input skb so allocate a + * new one. + */ + defer = skb; + skb = NULL; + } + + /* Don't trim `first_skb` until the end as we are + * walking that data now. + */ + } capturelen = min(iplen, remaining); - skb = iptfs_pskb_extract_seq(iplen, skbseq, data, capturelen); if (!skb) { - /* skip to next packet or done */ - data += capturelen; - continue; - } + skb = iptfs_pskb_extract_seq(iplen, skbseq, data, + capturelen); + if (!skb) { + /* skip to next packet or done */ + data += capturelen; + continue; + } - skb->protocol = protocol; - if (old_mac) { - /* rebuild the mac header */ - skb_set_mac_header(skb, -first_skb->mac_len); - memcpy(skb_mac_header(skb), old_mac, first_skb->mac_len); - eth_hdr(skb)->h_proto = skb->protocol; + skb->protocol = protocol; + if (old_mac) { + /* rebuild the mac header */ + skb_set_mac_header(skb, -first_skb->mac_len); + memcpy(skb_mac_header(skb), old_mac, first_skb->mac_len); + eth_hdr(skb)->h_proto = skb->protocol; + } } data += capturelen; @@ -735,6 +805,16 @@ static bool __input_process_payload(struct xfrm_state *x, u32 data, /* this should not happen from the above code */ XFRM_INC_STATS(net, LINUX_MIB_XFRMINIPTFSERROR); + if (first_skb && first_iplen && !defer && first_skb != xtfs->ra_newskb) { + /* first_skb is queued b/c !defer and not partial */ + if (pskb_trim(first_skb, first_iplen)) { + /* error trimming */ + list_del(&first_skb->list); + defer = first_skb; + } + first_skb->ip_summed = CHECKSUM_NONE; + } + /* Send the packets! */ list_for_each_entry_safe(skb, next, sublist, list) { skb_list_del_init(skb); @@ -742,7 +822,20 @@ static bool __input_process_payload(struct xfrm_state *x, u32 data, kfree_skb(skb); } done: - return false; + skb = skbseq->root_skb; + skb_abort_seq_read(skbseq); + + if (defer) { + consume_skb(defer); + } else if (!first_skb) { + /* skb is the original passed in skb, but we didn't get far + * enough to process it as the first_skb, if we had it would + * either be save in ra_newskb, trimmed and sent on as an skb or + * placed in defer to be freed. + */ + kfree_skb(skb); + } + return true; } /**