rxrpc: Clone received jumbo subpackets and queue separately

Split up received jumbo packets into separate skbuffs by cloning the
original skbuff for each subpacket and setting the offset and length of the
data in that subpacket in the skbuff's private data.  The subpackets are
then placed on the recvmsg queue separately.  The security class then gets
to revise the offset and length to remove its metadata.

If we fail to clone a packet, we just drop it and let the peer resend it.
The original packet gets used for the final subpacket.

This should make it easier to handle parallel decryption of the subpackets.
It also simplifies the handling of lost or misordered packets in the
queuing/buffering loop as the possibility of overlapping jumbo packets no
longer needs to be considered.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

1 files changed, 26 insertions, 70 deletions

diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
index 78fa0524156f..b19937776aa9 100644
--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -439,11 +439,11 @@ static int rxkad_secure_packet(struct rxrpc_call *call,
  * decrypt partial encryption on a packet (level 1 security)
  */
 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
-				 unsigned int offset, unsigned int len,
 				 rxrpc_seq_t seq,
 				 struct skcipher_request *req)
 {
 	struct rxkad_level1_hdr sechdr;
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 	struct rxrpc_crypt iv;
 	struct scatterlist sg[16];
 	bool aborted;
@@ -453,9 +453,9 @@ static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 
 	_enter("");
 
-	if (len < 8) {
+	if (sp->len < 8) {
 		aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_hdr", "V1H",
-					   RXKADSEALEDINCON);
+					     RXKADSEALEDINCON);
 		goto protocol_error;
 	}
 
@@ -463,7 +463,7 @@ static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 	 * directly into the target buffer.
 	 */
 	sg_init_table(sg, ARRAY_SIZE(sg));
-	ret = skb_to_sgvec(skb, sg, offset, 8);
+	ret = skb_to_sgvec(skb, sg, sp->offset, 8);
 	if (unlikely(ret < 0))
 		return ret;
 
@@ -477,12 +477,13 @@ static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 	skcipher_request_zero(req);
 
 	/* Extract the decrypted packet length */
-	if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
+	if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) {
 		aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_len", "XV1",
 					     RXKADDATALEN);
 		goto protocol_error;
 	}
-	len -= sizeof(sechdr);
+	sp->offset += sizeof(sechdr);
+	sp->len    -= sizeof(sechdr);
 
 	buf = ntohl(sechdr.data_size);
 	data_size = buf & 0xffff;
@@ -496,11 +497,12 @@ static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 		goto protocol_error;
 	}
 
-	if (data_size > len) {
+	if (data_size > sp->len) {
 		aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_datalen", "V1L",
 					     RXKADDATALEN);
 		goto protocol_error;
 	}
+	sp->len = data_size;
 
 	_leave(" = 0 [dlen=%x]", data_size);
 	return 0;
@@ -515,12 +517,12 @@ protocol_error:
  * wholly decrypt a packet (level 2 security)
  */
 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
-				 unsigned int offset, unsigned int len,
 				 rxrpc_seq_t seq,
 				 struct skcipher_request *req)
 {
 	const struct rxrpc_key_token *token;
 	struct rxkad_level2_hdr sechdr;
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 	struct rxrpc_crypt iv;
 	struct scatterlist _sg[4], *sg;
 	bool aborted;
@@ -528,9 +530,9 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 	u16 check;
 	int nsg, ret;
 
-	_enter(",{%d}", skb->len);
+	_enter(",{%d}", sp->len);
 
-	if (len < 8) {
+	if (sp->len < 8) {
 		aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_hdr", "V2H",
 					     RXKADSEALEDINCON);
 		goto protocol_error;
@@ -550,7 +552,7 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 	}
 
 	sg_init_table(sg, nsg);
-	ret = skb_to_sgvec(skb, sg, offset, len);
+	ret = skb_to_sgvec(skb, sg, sp->offset, sp->len);
 	if (unlikely(ret < 0)) {
 		if (sg != _sg)
 			kfree(sg);
@@ -563,19 +565,20 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
-	skcipher_request_set_crypt(req, sg, sg, len, iv.x);
+	skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x);
 	crypto_skcipher_decrypt(req);
 	skcipher_request_zero(req);
 	if (sg != _sg)
 		kfree(sg);
 
 	/* Extract the decrypted packet length */
-	if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
+	if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) {
 		aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_len", "XV2",
 					     RXKADDATALEN);
 		goto protocol_error;
 	}
-	len -= sizeof(sechdr);
+	sp->offset += sizeof(sechdr);
+	sp->len    -= sizeof(sechdr);
 
 	buf = ntohl(sechdr.data_size);
 	data_size = buf & 0xffff;
@@ -589,12 +592,13 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 		goto protocol_error;
 	}
 
-	if (data_size > len) {
+	if (data_size > sp->len) {
 		aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_datalen", "V2L",
 					     RXKADDATALEN);
 		goto protocol_error;
 	}
 
+	sp->len = data_size;
 	_leave(" = 0 [dlen=%x]", data_size);
 	return 0;
 
@@ -609,16 +613,15 @@ nomem:
 }
 
 /*
- * Verify the security on a received packet or subpacket (if part of a
- * jumbo packet).
+ * Verify the security on a received packet and the subpackets therein.
  */
-static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
-			       unsigned int offset, unsigned int len,
-			       rxrpc_seq_t seq, u16 expected_cksum)
+static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
 {
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 	struct skcipher_request	*req;
 	struct rxrpc_crypt iv;
 	struct scatterlist sg;
+	rxrpc_seq_t seq = sp->hdr.seq;
 	bool aborted;
 	u16 cksum;
 	u32 x, y;
@@ -654,7 +657,7 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 	if (cksum == 0)
 		cksum = 1; /* zero checksums are not permitted */
 
-	if (cksum != expected_cksum) {
+	if (cksum != sp->hdr.cksum) {
 		aborted = rxrpc_abort_eproto(call, skb, "rxkad_csum", "VCK",
 					     RXKADSEALEDINCON);
 		goto protocol_error;
@@ -664,9 +667,9 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 	case RXRPC_SECURITY_PLAIN:
 		return 0;
 	case RXRPC_SECURITY_AUTH:
-		return rxkad_verify_packet_1(call, skb, offset, len, seq, req);
+		return rxkad_verify_packet_1(call, skb, seq, req);
 	case RXRPC_SECURITY_ENCRYPT:
-		return rxkad_verify_packet_2(call, skb, offset, len, seq, req);
+		return rxkad_verify_packet_2(call, skb, seq, req);
 	default:
 		return -ENOANO;
 	}
@@ -678,52 +681,6 @@ protocol_error:
 }
 
 /*
- * Locate the data contained in a packet that was partially encrypted.
- */
-static void rxkad_locate_data_1(struct rxrpc_call *call, struct sk_buff *skb,
-				unsigned int *_offset, unsigned int *_len)
-{
-	struct rxkad_level1_hdr sechdr;
-
-	if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
-		BUG();
-	*_offset += sizeof(sechdr);
-	*_len = ntohl(sechdr.data_size) & 0xffff;
-}
-
-/*
- * Locate the data contained in a packet that was completely encrypted.
- */
-static void rxkad_locate_data_2(struct rxrpc_call *call, struct sk_buff *skb,
-				unsigned int *_offset, unsigned int *_len)
-{
-	struct rxkad_level2_hdr sechdr;
-
-	if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
-		BUG();
-	*_offset += sizeof(sechdr);
-	*_len = ntohl(sechdr.data_size) & 0xffff;
-}
-
-/*
- * Locate the data contained in an already decrypted packet.
- */
-static void rxkad_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
-			      unsigned int *_offset, unsigned int *_len)
-{
-	switch (call->conn->params.security_level) {
-	case RXRPC_SECURITY_AUTH:
-		rxkad_locate_data_1(call, skb, _offset, _len);
-		return;
-	case RXRPC_SECURITY_ENCRYPT:
-		rxkad_locate_data_2(call, skb, _offset, _len);
-		return;
-	default:
-		return;
-	}
-}
-
-/*
  * issue a challenge
  */
 static int rxkad_issue_challenge(struct rxrpc_connection *conn)
@@ -1397,7 +1354,6 @@ const struct rxrpc_security rxkad = {
 	.secure_packet			= rxkad_secure_packet,
 	.verify_packet			= rxkad_verify_packet,
 	.free_call_crypto		= rxkad_free_call_crypto,
-	.locate_data			= rxkad_locate_data,
 	.issue_challenge		= rxkad_issue_challenge,
 	.respond_to_challenge		= rxkad_respond_to_challenge,
 	.verify_response		= rxkad_verify_response,