[PATCH net 3/9] rxrpc: Use info in skbuff instead of reparsing a jumbo packet

From: David Howells
Date: Thu Aug 22 2019 - 09:45:59 EST

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Use the information now cached in the skbuff private data to avoid the need
to reparse a jumbo packet. We can find all the subpackets by dead
reckoning, so it's only necessary to note how many there are, whether the
last one is flagged as LAST_PACKET and whether any have the REQUEST_ACK
flag set.

This is necessary as once recvmsg() can see the packet, it can start
modifying it, such as doing in-place decryption.

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

net/rxrpc/ar-internal.h | 3 -
net/rxrpc/input.c | 233 ++++++++++++++++++++++-------------------------
net/rxrpc/recvmsg.c | 41 +++++---
3 files changed, 135 insertions(+), 142 deletions(-)

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 87cff6c218b6..20d7907a5bc6 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -617,8 +617,7 @@ struct rxrpc_call {
#define RXRPC_TX_ANNO_LAST 0x04
#define RXRPC_TX_ANNO_RESENT 0x08

-#define RXRPC_RX_ANNO_JUMBO 0x3f /* Jumbo subpacket number + 1 if not zero */
-#define RXRPC_RX_ANNO_JLAST 0x40 /* Set if last element of a jumbo packet */
+#define RXRPC_RX_ANNO_SUBPACKET 0x3f /* Subpacket number in jumbogram */
#define RXRPC_RX_ANNO_VERIFIED 0x80 /* Set if verified and decrypted */
rxrpc_seq_t tx_hard_ack; /* Dead slot in buffer; the first transmitted but
* not hard-ACK'd packet follows this.
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index b24492e5e429..140cede77655 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -405,10 +405,10 @@ static bool rxrpc_validate_data(struct sk_buff *skb)
* (that information is encoded in the ACK packet).
*/
static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
- u8 annotation, bool *_jumbo_bad)
+ bool is_jumbo, bool *_jumbo_bad)
{
/* Discard normal packets that are duplicates. */
- if (annotation == 0)
+ if (is_jumbo)
return;

/* Skip jumbo subpackets that are duplicates. When we've had three or
@@ -429,19 +429,17 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
enum rxrpc_call_state state;
- unsigned int offset = sizeof(struct rxrpc_wire_header);
- unsigned int ix;
+ unsigned int j;
rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
- rxrpc_seq_t seq0 = sp->hdr.seq, seq, hard_ack;
- bool immediate_ack = false, jumbo_bad = false, queued;
- u16 len;
- u8 ack = 0, flags, jumbo_flags, annotation = 0;
+ rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack;
+ bool immediate_ack = false, jumbo_bad = false;
+ u8 ack = 0;

_enter("{%u,%u},{%u,%u}",
- call->rx_hard_ack, call->rx_top, skb->len, seq);
+ call->rx_hard_ack, call->rx_top, skb->len, seq0);

- _proto("Rx DATA %%%u { #%u f=%02x }",
- sp->hdr.serial, seq0, sp->hdr.flags);
+ _proto("Rx DATA %%%u { #%u f=%02x n=%u }",
+ sp->hdr.serial, seq0, sp->hdr.flags, sp->nr_subpackets);

state = READ_ONCE(call->state);
if (state >= RXRPC_CALL_COMPLETE) {
@@ -473,147 +471,136 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
goto unlock;

call->ackr_prev_seq = seq0;
- seq = seq0;
-
hard_ack = READ_ONCE(call->rx_hard_ack);
- if (after(seq, hard_ack + call->rx_winsize)) {
- ack = RXRPC_ACK_EXCEEDS_WINDOW;
- ack_serial = serial;
- goto ack;
- }

- flags = sp->hdr.flags;
- if (flags & RXRPC_JUMBO_PACKET) {
+ if (sp->nr_subpackets > 1) {
if (call->nr_jumbo_bad > 3) {
ack = RXRPC_ACK_NOSPACE;
ack_serial = serial;
goto ack;
}
- annotation = 1;
}

-next_subpacket:
- queued = false;
- ix = seq & RXRPC_RXTX_BUFF_MASK;
- len = skb->len;
- if (flags & RXRPC_JUMBO_PACKET)
- len = RXRPC_JUMBO_DATALEN;
-
- if (flags & RXRPC_LAST_PACKET) {
- if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
- seq != call->rx_top) {
- rxrpc_proto_abort("LSN", call, seq);
- goto unlock;
+ for (j = 0; j < sp->nr_subpackets; j++) {
+ rxrpc_serial_t serial = sp->hdr.serial + j;
+ rxrpc_seq_t seq = seq0 + j;
+ unsigned int ix = seq & RXRPC_RXTX_BUFF_MASK;
+ bool terminal = (j == sp->nr_subpackets - 1);
+ bool last = terminal && (sp->rx_flags & RXRPC_SKB_INCL_LAST);
+ u8 flags, annotation = j;
+
+ _proto("Rx DATA+%u %%%u { #%x t=%u l=%u }",
+ j, serial, seq, terminal, last);
+
+ if (last) {
+ if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
+ seq != call->rx_top) {
+ rxrpc_proto_abort("LSN", call, seq);
+ goto unlock;
+ }
+ } else {
+ if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
+ after_eq(seq, call->rx_top)) {
+ rxrpc_proto_abort("LSA", call, seq);
+ goto unlock;
+ }
}
- } else {
- if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
- after_eq(seq, call->rx_top)) {
- rxrpc_proto_abort("LSA", call, seq);
- goto unlock;
+
+ flags = 0;
+ if (last)
+ flags |= RXRPC_LAST_PACKET;
+ if (!terminal)
+ flags |= RXRPC_JUMBO_PACKET;
+ if (test_bit(j, sp->rx_req_ack))
+ flags |= RXRPC_REQUEST_ACK;
+ trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
+
+ if (before_eq(seq, hard_ack)) {
+ ack = RXRPC_ACK_DUPLICATE;
+ ack_serial = serial;
+ continue;
}
- }

- trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
- if (before_eq(seq, hard_ack)) {
- ack = RXRPC_ACK_DUPLICATE;
- ack_serial = serial;
- goto skip;
- }
+ if (call->rxtx_buffer[ix]) {
+ rxrpc_input_dup_data(call, seq, sp->nr_subpackets > 1,
+ &jumbo_bad);
+ if (ack != RXRPC_ACK_DUPLICATE) {
+ ack = RXRPC_ACK_DUPLICATE;
+ ack_serial = serial;
+ }
+ immediate_ack = true;
+ continue;
+ }

- if (flags & RXRPC_REQUEST_ACK && !ack) {
- ack = RXRPC_ACK_REQUESTED;
- ack_serial = serial;
- }
+ if (after(seq, hard_ack + call->rx_winsize)) {
+ ack = RXRPC_ACK_EXCEEDS_WINDOW;
+ ack_serial = serial;
+ if (flags & RXRPC_JUMBO_PACKET) {
+ if (!jumbo_bad) {
+ call->nr_jumbo_bad++;
+ jumbo_bad = true;
+ }
+ }

- if (call->rxtx_buffer[ix]) {
- rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
- if (ack != RXRPC_ACK_DUPLICATE) {
- ack = RXRPC_ACK_DUPLICATE;
+ goto ack;
+ }
+
+ if (flags & RXRPC_REQUEST_ACK && !ack) {
+ ack = RXRPC_ACK_REQUESTED;
ack_serial = serial;
}
- immediate_ack = true;
- goto skip;
- }

- /* Queue the packet. We use a couple of memory barriers here as need
- * to make sure that rx_top is perceived to be set after the buffer
- * pointer and that the buffer pointer is set after the annotation and
- * the skb data.
- *
- * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
- * and also rxrpc_fill_out_ack().
- */
- if (flags & RXRPC_JUMBO_PACKET) {
- rxrpc_get_skb(skb, rxrpc_skb_rx_got);
- if (skb_copy_bits(skb, offset, &jumbo_flags, 1) < 0) {
- rxrpc_proto_abort("XJF", call, seq);
- goto unlock;
+ /* Queue the packet. We use a couple of memory barriers here as need
+ * to make sure that rx_top is perceived to be set after the buffer
+ * pointer and that the buffer pointer is set after the annotation and
+ * the skb data.
+ *
+ * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
+ * and also rxrpc_fill_out_ack().
+ */
+ if (!terminal)
+ rxrpc_get_skb(skb, rxrpc_skb_rx_got);
+ call->rxtx_annotations[ix] = annotation;
+ smp_wmb();
+ call->rxtx_buffer[ix] = skb;
+ if (after(seq, call->rx_top)) {
+ smp_store_release(&call->rx_top, seq);
+ } else if (before(seq, call->rx_top)) {
+ /* Send an immediate ACK if we fill in a hole */
+ if (!ack) {
+ ack = RXRPC_ACK_DELAY;
+ ack_serial = serial;
+ }
+ immediate_ack = true;
}
- }
- call->rxtx_annotations[ix] = annotation;
- smp_wmb();
- call->rxtx_buffer[ix] = skb;
- if (after(seq, call->rx_top)) {
- smp_store_release(&call->rx_top, seq);
- if (!(flags & RXRPC_JUMBO_PACKET)) {
+
+ if (terminal) {
/* From this point on, we're not allowed to touch the
* packet any longer as its ref now belongs to the Rx
* ring.
*/
skb = NULL;
}
- } else if (before(seq, call->rx_top)) {
- /* Send an immediate ACK if we fill in a hole */
- if (!ack) {
- ack = RXRPC_ACK_DELAY;
- ack_serial = serial;
- }
- immediate_ack = true;
- }
- if (flags & RXRPC_LAST_PACKET) {
- set_bit(RXRPC_CALL_RX_LAST, &call->flags);
- trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
- } else {
- trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
- }
- queued = true;

- if (after_eq(seq, call->rx_expect_next)) {
- if (after(seq, call->rx_expect_next)) {
- _net("OOS %u > %u", seq, call->rx_expect_next);
- ack = RXRPC_ACK_OUT_OF_SEQUENCE;
- ack_serial = serial;
+ if (last) {
+ set_bit(RXRPC_CALL_RX_LAST, &call->flags);
+ if (!ack) {
+ ack = RXRPC_ACK_DELAY;
+ ack_serial = serial;
+ }
+ trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
+ } else {
+ trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
}
- call->rx_expect_next = seq + 1;
- }

-skip:
- offset += len;
- if (flags & RXRPC_JUMBO_PACKET) {
- flags = jumbo_flags;
- offset += sizeof(struct rxrpc_jumbo_header);
- seq++;
- serial++;
- annotation++;
- if (flags & RXRPC_JUMBO_PACKET)
- annotation |= RXRPC_RX_ANNO_JLAST;
- if (after(seq, hard_ack + call->rx_winsize)) {
- ack = RXRPC_ACK_EXCEEDS_WINDOW;
- ack_serial = serial;
- if (!jumbo_bad) {
- call->nr_jumbo_bad++;
- jumbo_bad = true;
+ if (after_eq(seq, call->rx_expect_next)) {
+ if (after(seq, call->rx_expect_next)) {
+ _net("OOS %u > %u", seq, call->rx_expect_next);
+ ack = RXRPC_ACK_OUT_OF_SEQUENCE;
+ ack_serial = serial;
}
- goto ack;
+ call->rx_expect_next = seq + 1;
}
-
- _proto("Rx DATA Jumbo %%%u", serial);
- goto next_subpacket;
- }
-
- if (queued && flags & RXRPC_LAST_PACKET && !ack) {
- ack = RXRPC_ACK_DELAY;
- ack_serial = serial;
}

ack:
diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index 9a7e1bc9791d..e49eacfaf4d6 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -177,7 +177,8 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
struct sk_buff *skb;
rxrpc_serial_t serial;
rxrpc_seq_t hard_ack, top;
- u8 flags;
+ bool last = false;
+ u8 subpacket;
int ix;

_enter("%d", call->debug_id);
@@ -191,10 +192,13 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
skb = call->rxtx_buffer[ix];
rxrpc_see_skb(skb, rxrpc_skb_rx_rotated);
sp = rxrpc_skb(skb);
- flags = sp->hdr.flags;
- serial = sp->hdr.serial;
- if (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO)
- serial += (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO) - 1;
+
+ subpacket = call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
+ serial = sp->hdr.serial + subpacket;
+
+ if (subpacket == sp->nr_subpackets - 1 &&
+ sp->rx_flags & RXRPC_SKB_INCL_LAST)
+ last = true;

call->rxtx_buffer[ix] = NULL;
call->rxtx_annotations[ix] = 0;
@@ -203,9 +207,8 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)

rxrpc_free_skb(skb, rxrpc_skb_rx_freed);

- _debug("%u,%u,%02x", hard_ack, top, flags);
trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
- if (flags & RXRPC_LAST_PACKET) {
+ if (last) {
rxrpc_end_rx_phase(call, serial);
} else {
/* Check to see if there's an ACK that needs sending. */
@@ -233,18 +236,19 @@ static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
rxrpc_seq_t seq = sp->hdr.seq;
u16 cksum = sp->hdr.cksum;
+ u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;

_enter("");

/* For all but the head jumbo subpacket, the security checksum is in a
* jumbo header immediately prior to the data.
*/
- if ((annotation & RXRPC_RX_ANNO_JUMBO) > 1) {
+ if (subpacket > 0) {
__be16 tmp;
if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
BUG();
cksum = ntohs(tmp);
- seq += (annotation & RXRPC_RX_ANNO_JUMBO) - 1;
+ seq += subpacket;
}

return call->conn->security->verify_packet(call, skb, offset, len,
@@ -265,19 +269,18 @@ static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
u8 *_annotation,
unsigned int *_offset, unsigned int *_len)
{
+ struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
unsigned int offset = sizeof(struct rxrpc_wire_header);
unsigned int len;
int ret;
u8 annotation = *_annotation;
+ u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;

/* Locate the subpacket */
+ offset += subpacket * RXRPC_JUMBO_SUBPKTLEN;
len = skb->len - offset;
- if ((annotation & RXRPC_RX_ANNO_JUMBO) > 0) {
- offset += (((annotation & RXRPC_RX_ANNO_JUMBO) - 1) *
- RXRPC_JUMBO_SUBPKTLEN);
- len = (annotation & RXRPC_RX_ANNO_JLAST) ?
- skb->len - offset : RXRPC_JUMBO_SUBPKTLEN;
- }
+ if (subpacket < sp->nr_subpackets - 1)
+ len = RXRPC_JUMBO_DATALEN;

if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
@@ -303,6 +306,7 @@ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
{
struct rxrpc_skb_priv *sp;
struct sk_buff *skb;
+ rxrpc_serial_t serial;
rxrpc_seq_t hard_ack, top, seq;
size_t remain;
bool last;
@@ -339,9 +343,12 @@ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
rxrpc_see_skb(skb, rxrpc_skb_rx_seen);
sp = rxrpc_skb(skb);

- if (!(flags & MSG_PEEK))
+ if (!(flags & MSG_PEEK)) {
+ serial = sp->hdr.serial;
+ serial += call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
trace_rxrpc_receive(call, rxrpc_receive_front,
- sp->hdr.serial, seq);
+ serial, seq);
+ }

if (msg)
sock_recv_timestamp(msg, sock->sk, skb);

Next message: David Howells: "[PATCH net 2/9] rxrpc: Improve jumbo packet counting"
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