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-rw-r--r--net/sched/sch_cake.c454
1 files changed, 452 insertions, 2 deletions
diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index 2950a8d07887..930096d46c4f 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -725,6 +725,433 @@ static void flow_queue_add(struct cake_flow *flow, struct sk_buff *skb)
skb->next = NULL;
}
+static struct iphdr *cake_get_iphdr(const struct sk_buff *skb,
+ struct ipv6hdr *buf)
+{
+ unsigned int offset = skb_network_offset(skb);
+ struct iphdr *iph;
+
+ iph = skb_header_pointer(skb, offset, sizeof(struct iphdr), buf);
+
+ if (!iph)
+ return NULL;
+
+ if (iph->version == 4 && iph->protocol == IPPROTO_IPV6)
+ return skb_header_pointer(skb, offset + iph->ihl * 4,
+ sizeof(struct ipv6hdr), buf);
+
+ else if (iph->version == 4)
+ return iph;
+
+ else if (iph->version == 6)
+ return skb_header_pointer(skb, offset, sizeof(struct ipv6hdr),
+ buf);
+
+ return NULL;
+}
+
+static struct tcphdr *cake_get_tcphdr(const struct sk_buff *skb,
+ void *buf, unsigned int bufsize)
+{
+ unsigned int offset = skb_network_offset(skb);
+ const struct ipv6hdr *ipv6h;
+ const struct tcphdr *tcph;
+ const struct iphdr *iph;
+ struct ipv6hdr _ipv6h;
+ struct tcphdr _tcph;
+
+ ipv6h = skb_header_pointer(skb, offset, sizeof(_ipv6h), &_ipv6h);
+
+ if (!ipv6h)
+ return NULL;
+
+ if (ipv6h->version == 4) {
+ iph = (struct iphdr *)ipv6h;
+ offset += iph->ihl * 4;
+
+ /* special-case 6in4 tunnelling, as that is a common way to get
+ * v6 connectivity in the home
+ */
+ if (iph->protocol == IPPROTO_IPV6) {
+ ipv6h = skb_header_pointer(skb, offset,
+ sizeof(_ipv6h), &_ipv6h);
+
+ if (!ipv6h || ipv6h->nexthdr != IPPROTO_TCP)
+ return NULL;
+
+ offset += sizeof(struct ipv6hdr);
+
+ } else if (iph->protocol != IPPROTO_TCP) {
+ return NULL;
+ }
+
+ } else if (ipv6h->version == 6) {
+ if (ipv6h->nexthdr != IPPROTO_TCP)
+ return NULL;
+
+ offset += sizeof(struct ipv6hdr);
+ } else {
+ return NULL;
+ }
+
+ tcph = skb_header_pointer(skb, offset, sizeof(_tcph), &_tcph);
+ if (!tcph)
+ return NULL;
+
+ return skb_header_pointer(skb, offset,
+ min(__tcp_hdrlen(tcph), bufsize), buf);
+}
+
+static const void *cake_get_tcpopt(const struct tcphdr *tcph,
+ int code, int *oplen)
+{
+ /* inspired by tcp_parse_options in tcp_input.c */
+ int length = __tcp_hdrlen(tcph) - sizeof(struct tcphdr);
+ const u8 *ptr = (const u8 *)(tcph + 1);
+
+ while (length > 0) {
+ int opcode = *ptr++;
+ int opsize;
+
+ if (opcode == TCPOPT_EOL)
+ break;
+ if (opcode == TCPOPT_NOP) {
+ length--;
+ continue;
+ }
+ opsize = *ptr++;
+ if (opsize < 2 || opsize > length)
+ break;
+
+ if (opcode == code) {
+ *oplen = opsize;
+ return ptr;
+ }
+
+ ptr += opsize - 2;
+ length -= opsize;
+ }
+
+ return NULL;
+}
+
+/* Compare two SACK sequences. A sequence is considered greater if it SACKs more
+ * bytes than the other. In the case where both sequences ACKs bytes that the
+ * other doesn't, A is considered greater. DSACKs in A also makes A be
+ * considered greater.
+ *
+ * @return -1, 0 or 1 as normal compare functions
+ */
+static int cake_tcph_sack_compare(const struct tcphdr *tcph_a,
+ const struct tcphdr *tcph_b)
+{
+ const struct tcp_sack_block_wire *sack_a, *sack_b;
+ u32 ack_seq_a = ntohl(tcph_a->ack_seq);
+ u32 bytes_a = 0, bytes_b = 0;
+ int oplen_a, oplen_b;
+ bool first = true;
+
+ sack_a = cake_get_tcpopt(tcph_a, TCPOPT_SACK, &oplen_a);
+ sack_b = cake_get_tcpopt(tcph_b, TCPOPT_SACK, &oplen_b);
+
+ /* pointers point to option contents */
+ oplen_a -= TCPOLEN_SACK_BASE;
+ oplen_b -= TCPOLEN_SACK_BASE;
+
+ if (sack_a && oplen_a >= sizeof(*sack_a) &&
+ (!sack_b || oplen_b < sizeof(*sack_b)))
+ return -1;
+ else if (sack_b && oplen_b >= sizeof(*sack_b) &&
+ (!sack_a || oplen_a < sizeof(*sack_a)))
+ return 1;
+ else if ((!sack_a || oplen_a < sizeof(*sack_a)) &&
+ (!sack_b || oplen_b < sizeof(*sack_b)))
+ return 0;
+
+ while (oplen_a >= sizeof(*sack_a)) {
+ const struct tcp_sack_block_wire *sack_tmp = sack_b;
+ u32 start_a = get_unaligned_be32(&sack_a->start_seq);
+ u32 end_a = get_unaligned_be32(&sack_a->end_seq);
+ int oplen_tmp = oplen_b;
+ bool found = false;
+
+ /* DSACK; always considered greater to prevent dropping */
+ if (before(start_a, ack_seq_a))
+ return -1;
+
+ bytes_a += end_a - start_a;
+
+ while (oplen_tmp >= sizeof(*sack_tmp)) {
+ u32 start_b = get_unaligned_be32(&sack_tmp->start_seq);
+ u32 end_b = get_unaligned_be32(&sack_tmp->end_seq);
+
+ /* first time through we count the total size */
+ if (first)
+ bytes_b += end_b - start_b;
+
+ if (!after(start_b, start_a) && !before(end_b, end_a)) {
+ found = true;
+ if (!first)
+ break;
+ }
+ oplen_tmp -= sizeof(*sack_tmp);
+ sack_tmp++;
+ }
+
+ if (!found)
+ return -1;
+
+ oplen_a -= sizeof(*sack_a);
+ sack_a++;
+ first = false;
+ }
+
+ /* If we made it this far, all ranges SACKed by A are covered by B, so
+ * either the SACKs are equal, or B SACKs more bytes.
+ */
+ return bytes_b > bytes_a ? 1 : 0;
+}
+
+static void cake_tcph_get_tstamp(const struct tcphdr *tcph,
+ u32 *tsval, u32 *tsecr)
+{
+ const u8 *ptr;
+ int opsize;
+
+ ptr = cake_get_tcpopt(tcph, TCPOPT_TIMESTAMP, &opsize);
+
+ if (ptr && opsize == TCPOLEN_TIMESTAMP) {
+ *tsval = get_unaligned_be32(ptr);
+ *tsecr = get_unaligned_be32(ptr + 4);
+ }
+}
+
+static bool cake_tcph_may_drop(const struct tcphdr *tcph,
+ u32 tstamp_new, u32 tsecr_new)
+{
+ /* inspired by tcp_parse_options in tcp_input.c */
+ int length = __tcp_hdrlen(tcph) - sizeof(struct tcphdr);
+ const u8 *ptr = (const u8 *)(tcph + 1);
+ u32 tstamp, tsecr;
+
+ /* 3 reserved flags must be unset to avoid future breakage
+ * ACK must be set
+ * ECE/CWR are handled separately
+ * All other flags URG/PSH/RST/SYN/FIN must be unset
+ * 0x0FFF0000 = all TCP flags (confirm ACK=1, others zero)
+ * 0x00C00000 = CWR/ECE (handled separately)
+ * 0x0F3F0000 = 0x0FFF0000 & ~0x00C00000
+ */
+ if (((tcp_flag_word(tcph) &
+ cpu_to_be32(0x0F3F0000)) != TCP_FLAG_ACK))
+ return false;
+
+ while (length > 0) {
+ int opcode = *ptr++;
+ int opsize;
+
+ if (opcode == TCPOPT_EOL)
+ break;
+ if (opcode == TCPOPT_NOP) {
+ length--;
+ continue;
+ }
+ opsize = *ptr++;
+ if (opsize < 2 || opsize > length)
+ break;
+
+ switch (opcode) {
+ case TCPOPT_MD5SIG: /* doesn't influence state */
+ break;
+
+ case TCPOPT_SACK: /* stricter checking performed later */
+ if (opsize % 8 != 2)
+ return false;
+ break;
+
+ case TCPOPT_TIMESTAMP:
+ /* only drop timestamps lower than new */
+ if (opsize != TCPOLEN_TIMESTAMP)
+ return false;
+ tstamp = get_unaligned_be32(ptr);
+ tsecr = get_unaligned_be32(ptr + 4);
+ if (after(tstamp, tstamp_new) ||
+ after(tsecr, tsecr_new))
+ return false;
+ break;
+
+ case TCPOPT_MSS: /* these should only be set on SYN */
+ case TCPOPT_WINDOW:
+ case TCPOPT_SACK_PERM:
+ case TCPOPT_FASTOPEN:
+ case TCPOPT_EXP:
+ default: /* don't drop if any unknown options are present */
+ return false;
+ }
+
+ ptr += opsize - 2;
+ length -= opsize;
+ }
+
+ return true;
+}
+
+static struct sk_buff *cake_ack_filter(struct cake_sched_data *q,
+ struct cake_flow *flow)
+{
+ bool aggressive = q->ack_filter == CAKE_ACK_AGGRESSIVE;
+ struct sk_buff *elig_ack = NULL, *elig_ack_prev = NULL;
+ struct sk_buff *skb_check, *skb_prev = NULL;
+ const struct ipv6hdr *ipv6h, *ipv6h_check;
+ unsigned char _tcph[64], _tcph_check[64];
+ const struct tcphdr *tcph, *tcph_check;
+ const struct iphdr *iph, *iph_check;
+ struct ipv6hdr _iph, _iph_check;
+ const struct sk_buff *skb;
+ int seglen, num_found = 0;
+ u32 tstamp = 0, tsecr = 0;
+ __be32 elig_flags = 0;
+ int sack_comp;
+
+ /* no other possible ACKs to filter */
+ if (flow->head == flow->tail)
+ return NULL;
+
+ skb = flow->tail;
+ tcph = cake_get_tcphdr(skb, _tcph, sizeof(_tcph));
+ iph = cake_get_iphdr(skb, &_iph);
+ if (!tcph)
+ return NULL;
+
+ cake_tcph_get_tstamp(tcph, &tstamp, &tsecr);
+
+ /* the 'triggering' packet need only have the ACK flag set.
+ * also check that SYN is not set, as there won't be any previous ACKs.
+ */
+ if ((tcp_flag_word(tcph) &
+ (TCP_FLAG_ACK | TCP_FLAG_SYN)) != TCP_FLAG_ACK)
+ return NULL;
+
+ /* the 'triggering' ACK is at the tail of the queue, we have already
+ * returned if it is the only packet in the flow. loop through the rest
+ * of the queue looking for pure ACKs with the same 5-tuple as the
+ * triggering one.
+ */
+ for (skb_check = flow->head;
+ skb_check && skb_check != skb;
+ skb_prev = skb_check, skb_check = skb_check->next) {
+ iph_check = cake_get_iphdr(skb_check, &_iph_check);
+ tcph_check = cake_get_tcphdr(skb_check, &_tcph_check,
+ sizeof(_tcph_check));
+
+ /* only TCP packets with matching 5-tuple are eligible, and only
+ * drop safe headers
+ */
+ if (!tcph_check || iph->version != iph_check->version ||
+ tcph_check->source != tcph->source ||
+ tcph_check->dest != tcph->dest)
+ continue;
+
+ if (iph_check->version == 4) {
+ if (iph_check->saddr != iph->saddr ||
+ iph_check->daddr != iph->daddr)
+ continue;
+
+ seglen = ntohs(iph_check->tot_len) -
+ (4 * iph_check->ihl);
+ } else if (iph_check->version == 6) {
+ ipv6h = (struct ipv6hdr *)iph;
+ ipv6h_check = (struct ipv6hdr *)iph_check;
+
+ if (ipv6_addr_cmp(&ipv6h_check->saddr, &ipv6h->saddr) ||
+ ipv6_addr_cmp(&ipv6h_check->daddr, &ipv6h->daddr))
+ continue;
+
+ seglen = ntohs(ipv6h_check->payload_len);
+ } else {
+ WARN_ON(1); /* shouldn't happen */
+ continue;
+ }
+
+ /* If the ECE/CWR flags changed from the previous eligible
+ * packet in the same flow, we should no longer be dropping that
+ * previous packet as this would lose information.
+ */
+ if (elig_ack && (tcp_flag_word(tcph_check) &
+ (TCP_FLAG_ECE | TCP_FLAG_CWR)) != elig_flags) {
+ elig_ack = NULL;
+ elig_ack_prev = NULL;
+ num_found--;
+ }
+
+ /* Check TCP options and flags, don't drop ACKs with segment
+ * data, and don't drop ACKs with a higher cumulative ACK
+ * counter than the triggering packet. Check ACK seqno here to
+ * avoid parsing SACK options of packets we are going to exclude
+ * anyway.
+ */
+ if (!cake_tcph_may_drop(tcph_check, tstamp, tsecr) ||
+ (seglen - __tcp_hdrlen(tcph_check)) != 0 ||
+ after(ntohl(tcph_check->ack_seq), ntohl(tcph->ack_seq)))
+ continue;
+
+ /* Check SACK options. The triggering packet must SACK more data
+ * than the ACK under consideration, or SACK the same range but
+ * have a larger cumulative ACK counter. The latter is a
+ * pathological case, but is contained in the following check
+ * anyway, just to be safe.
+ */
+ sack_comp = cake_tcph_sack_compare(tcph_check, tcph);
+
+ if (sack_comp < 0 ||
+ (ntohl(tcph_check->ack_seq) == ntohl(tcph->ack_seq) &&
+ sack_comp == 0))
+ continue;
+
+ /* At this point we have found an eligible pure ACK to drop; if
+ * we are in aggressive mode, we are done. Otherwise, keep
+ * searching unless this is the second eligible ACK we
+ * found.
+ *
+ * Since we want to drop ACK closest to the head of the queue,
+ * save the first eligible ACK we find, even if we need to loop
+ * again.
+ */
+ if (!elig_ack) {
+ elig_ack = skb_check;
+ elig_ack_prev = skb_prev;
+ elig_flags = (tcp_flag_word(tcph_check)
+ & (TCP_FLAG_ECE | TCP_FLAG_CWR));
+ }
+
+ if (num_found++ > 0)
+ goto found;
+ }
+
+ /* We made it through the queue without finding two eligible ACKs . If
+ * we found a single eligible ACK we can drop it in aggressive mode if
+ * we can guarantee that this does not interfere with ECN flag
+ * information. We ensure this by dropping it only if the enqueued
+ * packet is consecutive with the eligible ACK, and their flags match.
+ */
+ if (elig_ack && aggressive && elig_ack->next == skb &&
+ (elig_flags == (tcp_flag_word(tcph) &
+ (TCP_FLAG_ECE | TCP_FLAG_CWR))))
+ goto found;
+
+ return NULL;
+
+found:
+ if (elig_ack_prev)
+ elig_ack_prev->next = elig_ack->next;
+ else
+ flow->head = elig_ack->next;
+
+ elig_ack->next = NULL;
+
+ return elig_ack;
+}
+
static u64 cake_ewma(u64 avg, u64 sample, u32 shift)
{
avg -= avg >> shift;
@@ -934,6 +1361,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct cake_sched_data *q = qdisc_priv(sch);
int len = qdisc_pkt_len(skb);
int uninitialized_var(ret);
+ struct sk_buff *ack = NULL;
ktime_t now = ktime_get();
struct cake_tin_data *b;
struct cake_flow *flow;
@@ -980,8 +1408,24 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch,
cobalt_set_enqueue_time(skb, now);
flow_queue_add(flow, skb);
- sch->q.qlen++;
- q->buffer_used += skb->truesize;
+ if (q->ack_filter)
+ ack = cake_ack_filter(q, flow);
+
+ if (ack) {
+ b->ack_drops++;
+ sch->qstats.drops++;
+ b->bytes += qdisc_pkt_len(ack);
+ len -= qdisc_pkt_len(ack);
+ q->buffer_used += skb->truesize - ack->truesize;
+ if (q->rate_flags & CAKE_FLAG_INGRESS)
+ cake_advance_shaper(q, b, ack, now, true);
+
+ qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(ack));
+ consume_skb(ack);
+ } else {
+ sch->q.qlen++;
+ q->buffer_used += skb->truesize;
+ }
/* stats */
b->packets++;
@@ -1530,6 +1974,9 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt,
q->rate_flags &= ~CAKE_FLAG_INGRESS;
}
+ if (tb[TCA_CAKE_ACK_FILTER])
+ q->ack_filter = nla_get_u32(tb[TCA_CAKE_ACK_FILTER]);
+
if (tb[TCA_CAKE_MEMORY])
q->buffer_config_limit = nla_get_u32(tb[TCA_CAKE_MEMORY]);
@@ -1661,6 +2108,9 @@ static int cake_dump(struct Qdisc *sch, struct sk_buff *skb)
!!(q->rate_flags & CAKE_FLAG_INGRESS)))
goto nla_put_failure;
+ if (nla_put_u32(skb, TCA_CAKE_ACK_FILTER, q->ack_filter))
+ goto nla_put_failure;
+
return nla_nest_end(skb, opts);
nla_put_failure:
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-17 06:19:00 +0000