[PATCH net-next 0/7] mptcp: Optimize output options and add MP_FAIL

[PATCH net-next 0/7] mptcp: Optimize output options and add MP_FAIL

[Mat Martineau]

This patch set contains two groups of changes that we've been testing in
the MPTCP tree.


The first optimizes the code path and data structure for populating
MPTCP option headers when transmitting.

Patch 1 reorganizes code to reduce the number of conditionals that need
to be evaluated in common cases.

Patch 2 rearranges struct mptcp_out_options to save 80 bytes (on x86_64).


The next five patches add partial support for the MP_FAIL option as
defined in RFC 8684. MP_FAIL is an option header used to cleanly handle
MPTCP checksum failures. When the MPTCP checksum detects an error in the
MPTCP DSS header or the data mapped by that header, the receiver uses a
TCP RST with MP_FAIL to close the subflow that experienced the error and
provide associated MPTCP sequence number information to the peer. RFC
8684 also describes how a single-subflow connection can discard corrupt
data and remain connected under certain conditions using MP_FAIL, but
that feature is not implemented here.

Patches 3-5 implement MP_FAIL transmit and receive, and integrates with
checksum validation.

Patches 6 & 7 add MP_FAIL selftests and the MIBs required for those
tests.


Geliang Tang (5):
  mptcp: MP_FAIL suboption sending
  mptcp: MP_FAIL suboption receiving
  mptcp: send out MP_FAIL when data checksum fails
  mptcp: add the mibs for MP_FAIL
  selftests: mptcp: add MP_FAIL mibs check

Paolo Abeni (2):
  mptcp: optimize out option generation
  mptcp: shrink mptcp_out_options struct

 include/net/mptcp.h                           |  29 +-
 net/mptcp/mib.c                               |   2 +
 net/mptcp/mib.h                               |   2 +
 net/mptcp/options.c                           | 305 +++++++++++-------
 net/mptcp/pm.c                                |   5 +
 net/mptcp/protocol.h                          |  20 ++
 net/mptcp/subflow.c                           |  16 +
 .../testing/selftests/net/mptcp/mptcp_join.sh |  38 +++
 8 files changed, 295 insertions(+), 122 deletions(-)


base-commit: 3a62c333497b164868fdcd241842a1dd4e331825
-- 
2.33.0

[PATCH net-next 1/7] mptcp: optimize out option generation

[Mat Martineau]

From: Paolo Abeni <pabeni@redhat.com>

Currently we have several protocol constraints on MPTCP options
generation (e.g. MPC and MPJ subopt are mutually exclusive)
and some additional ones required by our implementation
(e.g. almost all ADD_ADDR variant are mutually exclusive with
everything else).

We can leverage the above to optimize the out option generation:
we check DSS/MPC/MPJ presence in a mutually exclusive way,
avoiding many unneeded conditionals in the common cases.

Additionally extend the existing constraints on ADD_ADDR opt on
all subvariants, so that it becomes fully mutually exclusive with
the above and we can skip another conditional statement for the
common case.

This change is also needed by the next patch.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/options.c  | 229 +++++++++++++++++++++++--------------------
 net/mptcp/protocol.h |   1 +
 2 files changed, 121 insertions(+), 109 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 4c37f4b215ee..1a59b3045a33 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -592,6 +592,7 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 		dss_size = map_size;
 		if (skb && snd_data_fin_enable)
 			mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
+		opts->suboptions = OPTION_MPTCP_DSS;
 		ret = true;
 	}
 
@@ -615,6 +616,7 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 		opts->ext_copy.ack64 = 0;
 	}
 	opts->ext_copy.use_ack = 1;
+	opts->suboptions = OPTION_MPTCP_DSS;
 	WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
 
 	/* Add kind/length/subtype/flag overhead if mapping is not populated */
@@ -686,8 +688,13 @@ static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *
 	if (drop_other_suboptions) {
 		pr_debug("drop other suboptions");
 		opts->suboptions = 0;
-		opts->ext_copy.use_ack = 0;
-		opts->ext_copy.use_map = 0;
+
+		/* note that e.g. DSS could have written into the memory
+		 * aliased by ahmac, we must reset the field here
+		 * to avoid appending the hmac even for ADD_ADDR echo
+		 * options
+		 */
+		opts->ahmac = 0;
 		*size -= opt_size;
 	}
 	opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
@@ -739,7 +746,12 @@ static bool mptcp_established_options_mp_prio(struct sock *sk,
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 
-	if (!subflow->send_mp_prio)
+	/* can't send MP_PRIO with MPC, as they share the same option space:
+	 * 'backup'. Also it makes no sense at all
+	 */
+	if (!subflow->send_mp_prio ||
+	    ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
+	      OPTION_MPTCP_MPC_ACK) & opts->suboptions))
 		return false;
 
 	/* account for the trailing 'nop' option */
@@ -1198,8 +1210,74 @@ static u16 mptcp_make_csum(const struct mptcp_ext *mpext)
 void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 			 struct mptcp_out_options *opts)
 {
-	if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
-	     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
+	/* RST is mutually exclusive with everything else */
+	if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) {
+		*ptr++ = mptcp_option(MPTCPOPT_RST,
+				      TCPOLEN_MPTCP_RST,
+				      opts->reset_transient,
+				      opts->reset_reason);
+		return;
+	}
+
+	/* DSS, MPC, MPJ and ADD_ADDR are mutually exclusive, see
+	 * mptcp_established_options*()
+	 */
+	if (likely(OPTION_MPTCP_DSS & opts->suboptions)) {
+		struct mptcp_ext *mpext = &opts->ext_copy;
+		u8 len = TCPOLEN_MPTCP_DSS_BASE;
+		u8 flags = 0;
+
+		if (mpext->use_ack) {
+			flags = MPTCP_DSS_HAS_ACK;
+			if (mpext->ack64) {
+				len += TCPOLEN_MPTCP_DSS_ACK64;
+				flags |= MPTCP_DSS_ACK64;
+			} else {
+				len += TCPOLEN_MPTCP_DSS_ACK32;
+			}
+		}
+
+		if (mpext->use_map) {
+			len += TCPOLEN_MPTCP_DSS_MAP64;
+
+			/* Use only 64-bit mapping flags for now, add
+			 * support for optional 32-bit mappings later.
+			 */
+			flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
+			if (mpext->data_fin)
+				flags |= MPTCP_DSS_DATA_FIN;
+
+			if (opts->csum_reqd)
+				len += TCPOLEN_MPTCP_DSS_CHECKSUM;
+		}
+
+		*ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
+
+		if (mpext->use_ack) {
+			if (mpext->ack64) {
+				put_unaligned_be64(mpext->data_ack, ptr);
+				ptr += 2;
+			} else {
+				put_unaligned_be32(mpext->data_ack32, ptr);
+				ptr += 1;
+			}
+		}
+
+		if (mpext->use_map) {
+			put_unaligned_be64(mpext->data_seq, ptr);
+			ptr += 2;
+			put_unaligned_be32(mpext->subflow_seq, ptr);
+			ptr += 1;
+			if (opts->csum_reqd) {
+				put_unaligned_be32(mpext->data_len << 16 |
+						   mptcp_make_csum(mpext), ptr);
+			} else {
+				put_unaligned_be32(mpext->data_len << 16 |
+						   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
+			}
+		}
+	} else if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
+		    OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
 		u8 len, flag = MPTCP_CAP_HMAC_SHA256;
 
 		if (OPTION_MPTCP_MPC_SYN & opts->suboptions) {
@@ -1246,10 +1324,31 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 					   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
 		}
 		ptr += 1;
-	}
 
-mp_capable_done:
-	if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
+		/* MPC is additionally mutually exclusive with MP_PRIO */
+		goto mp_capable_done;
+	} else if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
+		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+				      TCPOLEN_MPTCP_MPJ_SYN,
+				      opts->backup, opts->join_id);
+		put_unaligned_be32(opts->token, ptr);
+		ptr += 1;
+		put_unaligned_be32(opts->nonce, ptr);
+		ptr += 1;
+	} else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
+		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+				      TCPOLEN_MPTCP_MPJ_SYNACK,
+				      opts->backup, opts->join_id);
+		put_unaligned_be64(opts->thmac, ptr);
+		ptr += 2;
+		put_unaligned_be32(opts->nonce, ptr);
+		ptr += 1;
+	} else if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
+		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+				      TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
+		memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
+		ptr += 5;
+	} else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
 		u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
 		u8 echo = MPTCP_ADDR_ECHO;
 
@@ -1307,6 +1406,19 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 		}
 	}
 
+	if (OPTION_MPTCP_PRIO & opts->suboptions) {
+		const struct sock *ssk = (const struct sock *)tp;
+		struct mptcp_subflow_context *subflow;
+
+		subflow = mptcp_subflow_ctx(ssk);
+		subflow->send_mp_prio = 0;
+
+		*ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
+				      TCPOLEN_MPTCP_PRIO,
+				      opts->backup, TCPOPT_NOP);
+	}
+
+mp_capable_done:
 	if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
 		u8 i = 1;
 
@@ -1327,107 +1439,6 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 		}
 	}
 
-	if (OPTION_MPTCP_PRIO & opts->suboptions) {
-		const struct sock *ssk = (const struct sock *)tp;
-		struct mptcp_subflow_context *subflow;
-
-		subflow = mptcp_subflow_ctx(ssk);
-		subflow->send_mp_prio = 0;
-
-		*ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
-				      TCPOLEN_MPTCP_PRIO,
-				      opts->backup, TCPOPT_NOP);
-	}
-
-	if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
-		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
-				      TCPOLEN_MPTCP_MPJ_SYN,
-				      opts->backup, opts->join_id);
-		put_unaligned_be32(opts->token, ptr);
-		ptr += 1;
-		put_unaligned_be32(opts->nonce, ptr);
-		ptr += 1;
-	}
-
-	if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
-		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
-				      TCPOLEN_MPTCP_MPJ_SYNACK,
-				      opts->backup, opts->join_id);
-		put_unaligned_be64(opts->thmac, ptr);
-		ptr += 2;
-		put_unaligned_be32(opts->nonce, ptr);
-		ptr += 1;
-	}
-
-	if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
-		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
-				      TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
-		memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
-		ptr += 5;
-	}
-
-	if (OPTION_MPTCP_RST & opts->suboptions)
-		*ptr++ = mptcp_option(MPTCPOPT_RST,
-				      TCPOLEN_MPTCP_RST,
-				      opts->reset_transient,
-				      opts->reset_reason);
-
-	if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
-		struct mptcp_ext *mpext = &opts->ext_copy;
-		u8 len = TCPOLEN_MPTCP_DSS_BASE;
-		u8 flags = 0;
-
-		if (mpext->use_ack) {
-			flags = MPTCP_DSS_HAS_ACK;
-			if (mpext->ack64) {
-				len += TCPOLEN_MPTCP_DSS_ACK64;
-				flags |= MPTCP_DSS_ACK64;
-			} else {
-				len += TCPOLEN_MPTCP_DSS_ACK32;
-			}
-		}
-
-		if (mpext->use_map) {
-			len += TCPOLEN_MPTCP_DSS_MAP64;
-
-			/* Use only 64-bit mapping flags for now, add
-			 * support for optional 32-bit mappings later.
-			 */
-			flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
-			if (mpext->data_fin)
-				flags |= MPTCP_DSS_DATA_FIN;
-
-			if (opts->csum_reqd)
-				len += TCPOLEN_MPTCP_DSS_CHECKSUM;
-		}
-
-		*ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
-
-		if (mpext->use_ack) {
-			if (mpext->ack64) {
-				put_unaligned_be64(mpext->data_ack, ptr);
-				ptr += 2;
-			} else {
-				put_unaligned_be32(mpext->data_ack32, ptr);
-				ptr += 1;
-			}
-		}
-
-		if (mpext->use_map) {
-			put_unaligned_be64(mpext->data_seq, ptr);
-			ptr += 2;
-			put_unaligned_be32(mpext->subflow_seq, ptr);
-			ptr += 1;
-			if (opts->csum_reqd) {
-				put_unaligned_be32(mpext->data_len << 16 |
-						   mptcp_make_csum(mpext), ptr);
-			} else {
-				put_unaligned_be32(mpext->data_len << 16 |
-						   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
-			}
-		}
-	}
-
 	if (tp)
 		mptcp_set_rwin(tp);
 }
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 7cd3d5979bcd..d276ce16f126 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -26,6 +26,7 @@
 #define OPTION_MPTCP_FASTCLOSE	BIT(8)
 #define OPTION_MPTCP_PRIO	BIT(9)
 #define OPTION_MPTCP_RST	BIT(10)
+#define OPTION_MPTCP_DSS	BIT(11)
 
 /* MPTCP option subtypes */
 #define MPTCPOPT_MP_CAPABLE	0
-- 
2.33.0

[PATCH net-next 2/7] mptcp: shrink mptcp_out_options struct

[Mat Martineau]

From: Paolo Abeni <pabeni@redhat.com>

After the previous patch we can alias with a union several
fields in mptcp_out_options. Such struct is stack allocated and
memset() for each plain TCP out packet. Every saved byted counts.

Before:
pahole -EC mptcp_out_options
 # ...
/* size: 136, cachelines: 3, members: 17 */

After:
pahole -EC mptcp_out_options
 # ...
/* size: 56, cachelines: 1, members: 9 */

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 include/net/mptcp.h | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 8b5af683a818..3236010afa29 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -58,10 +58,6 @@ struct mptcp_addr_info {
 struct mptcp_out_options {
 #if IS_ENABLED(CONFIG_MPTCP)
 	u16 suboptions;
-	u64 sndr_key;
-	u64 rcvr_key;
-	u64 ahmac;
-	struct mptcp_addr_info addr;
 	struct mptcp_rm_list rm_list;
 	u8 join_id;
 	u8 backup;
@@ -69,11 +65,23 @@ struct mptcp_out_options {
 	   reset_transient:1,
 	   csum_reqd:1,
 	   allow_join_id0:1;
-	u32 nonce;
-	u64 thmac;
-	u32 token;
-	u8 hmac[20];
-	struct mptcp_ext ext_copy;
+	union {
+		struct {
+			u64 sndr_key;
+			u64 rcvr_key;
+		};
+		struct {
+			struct mptcp_addr_info addr;
+			u64 ahmac;
+		};
+		struct mptcp_ext ext_copy;
+		struct {
+			u32 nonce;
+			u32 token;
+			u64 thmac;
+			u8 hmac[20];
+		};
+	};
 #endif
 };
 
-- 
2.33.0

[PATCH net-next 3/7] mptcp: MP_FAIL suboption sending

[Mat Martineau]

From: Geliang Tang <geliangtang@xiaomi.com>

This patch added the MP_FAIL suboption sending support.

Add a new flag named send_mp_fail in struct mptcp_subflow_context. If
this flag is set, send out MP_FAIL suboption.

Add a new member fail_seq in struct mptcp_out_options to save the data
sequence number to put into the MP_FAIL suboption.

An MP_FAIL option could be included in a RST or on the subflow-level
ACK.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 include/net/mptcp.h  |  5 +++-
 net/mptcp/options.c  | 59 +++++++++++++++++++++++++++++++++++++++++---
 net/mptcp/protocol.h |  3 +++
 3 files changed, 62 insertions(+), 5 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 3236010afa29..6026bbefbffd 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -74,7 +74,10 @@ struct mptcp_out_options {
 			struct mptcp_addr_info addr;
 			u64 ahmac;
 		};
-		struct mptcp_ext ext_copy;
+		struct {
+			struct mptcp_ext ext_copy;
+			u64 fail_seq;
+		};
 		struct {
 			u32 nonce;
 			u32 token;
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 1a59b3045a33..f2ebdd55d3cc 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -767,7 +767,7 @@ static bool mptcp_established_options_mp_prio(struct sock *sk,
 	return true;
 }
 
-static noinline void mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
+static noinline bool mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
 						   unsigned int *size,
 						   unsigned int remaining,
 						   struct mptcp_out_options *opts)
@@ -775,12 +775,36 @@ static noinline void mptcp_established_options_rst(struct sock *sk, struct sk_bu
 	const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 
 	if (remaining < TCPOLEN_MPTCP_RST)
-		return;
+		return false;
 
 	*size = TCPOLEN_MPTCP_RST;
 	opts->suboptions |= OPTION_MPTCP_RST;
 	opts->reset_transient = subflow->reset_transient;
 	opts->reset_reason = subflow->reset_reason;
+
+	return true;
+}
+
+static bool mptcp_established_options_mp_fail(struct sock *sk,
+					      unsigned int *size,
+					      unsigned int remaining,
+					      struct mptcp_out_options *opts)
+{
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+	if (likely(!subflow->send_mp_fail))
+		return false;
+
+	if (remaining < TCPOLEN_MPTCP_FAIL)
+		return false;
+
+	*size = TCPOLEN_MPTCP_FAIL;
+	opts->suboptions |= OPTION_MPTCP_FAIL;
+	opts->fail_seq = subflow->map_seq;
+
+	pr_debug("MP_FAIL fail_seq=%llu", opts->fail_seq);
+
+	return true;
 }
 
 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
@@ -799,15 +823,28 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 		return false;
 
 	if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
-		mptcp_established_options_rst(sk, skb, size, remaining, opts);
+		if (mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) {
+			*size += opt_size;
+			remaining -= opt_size;
+		}
+		if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) {
+			*size += opt_size;
+			remaining -= opt_size;
+		}
 		return true;
 	}
 
 	snd_data_fin = mptcp_data_fin_enabled(msk);
 	if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, remaining, opts))
 		ret = true;
-	else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, remaining, opts))
+	else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, remaining, opts)) {
 		ret = true;
+		if (mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) {
+			*size += opt_size;
+			remaining -= opt_size;
+			return true;
+		}
+	}
 
 	/* we reserved enough space for the above options, and exceeding the
 	 * TCP option space would be fatal
@@ -1210,6 +1247,20 @@ static u16 mptcp_make_csum(const struct mptcp_ext *mpext)
 void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 			 struct mptcp_out_options *opts)
 {
+	if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) {
+		const struct sock *ssk = (const struct sock *)tp;
+		struct mptcp_subflow_context *subflow;
+
+		subflow = mptcp_subflow_ctx(ssk);
+		subflow->send_mp_fail = 0;
+
+		*ptr++ = mptcp_option(MPTCPOPT_MP_FAIL,
+				      TCPOLEN_MPTCP_FAIL,
+				      0, 0);
+		put_unaligned_be64(opts->fail_seq, ptr);
+		ptr += 2;
+	}
+
 	/* RST is mutually exclusive with everything else */
 	if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) {
 		*ptr++ = mptcp_option(MPTCPOPT_RST,
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index d276ce16f126..3e4a79cf520a 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -27,6 +27,7 @@
 #define OPTION_MPTCP_PRIO	BIT(9)
 #define OPTION_MPTCP_RST	BIT(10)
 #define OPTION_MPTCP_DSS	BIT(11)
+#define OPTION_MPTCP_FAIL	BIT(12)
 
 /* MPTCP option subtypes */
 #define MPTCPOPT_MP_CAPABLE	0
@@ -68,6 +69,7 @@
 #define TCPOLEN_MPTCP_PRIO_ALIGN	4
 #define TCPOLEN_MPTCP_FASTCLOSE		12
 #define TCPOLEN_MPTCP_RST		4
+#define TCPOLEN_MPTCP_FAIL		12
 
 #define TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM	(TCPOLEN_MPTCP_DSS_CHECKSUM + TCPOLEN_MPTCP_MPC_ACK_DATA)
 
@@ -429,6 +431,7 @@ struct mptcp_subflow_context {
 		mpc_map : 1,
 		backup : 1,
 		send_mp_prio : 1,
+		send_mp_fail : 1,
 		rx_eof : 1,
 		can_ack : 1,        /* only after processing the remote a key */
 		disposable : 1,	    /* ctx can be free at ulp release time */
-- 
2.33.0

[PATCH net-next 4/7] mptcp: MP_FAIL suboption receiving

[Mat Martineau]

From: Geliang Tang <geliangtang@xiaomi.com>

This patch added handling for receiving MP_FAIL suboption.

Add a new members mp_fail and fail_seq in struct mptcp_options_received.
When MP_FAIL suboption is received, set mp_fail to 1 and save the sequence
number to fail_seq.

Then invoke mptcp_pm_mp_fail_received to deal with the MP_FAIL suboption.

Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/options.c  | 16 ++++++++++++++++
 net/mptcp/pm.c       |  5 +++++
 net/mptcp/protocol.h |  3 +++
 3 files changed, 24 insertions(+)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index f2ebdd55d3cc..fa287a49dc84 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -336,6 +336,16 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 		mp_opt->reset_reason = *ptr;
 		break;
 
+	case MPTCPOPT_MP_FAIL:
+		if (opsize != TCPOLEN_MPTCP_FAIL)
+			break;
+
+		ptr += 2;
+		mp_opt->mp_fail = 1;
+		mp_opt->fail_seq = get_unaligned_be64(ptr);
+		pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq);
+		break;
+
 	default:
 		break;
 	}
@@ -364,6 +374,7 @@ void mptcp_get_options(const struct sock *sk,
 	mp_opt->reset = 0;
 	mp_opt->csum_reqd = READ_ONCE(msk->csum_enabled);
 	mp_opt->deny_join_id0 = 0;
+	mp_opt->mp_fail = 0;
 
 	length = (th->doff * 4) - sizeof(struct tcphdr);
 	ptr = (const unsigned char *)(th + 1);
@@ -1145,6 +1156,11 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 		mp_opt.mp_prio = 0;
 	}
 
+	if (mp_opt.mp_fail) {
+		mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq);
+		mp_opt.mp_fail = 0;
+	}
+
 	if (mp_opt.reset) {
 		subflow->reset_seen = 1;
 		subflow->reset_reason = mp_opt.reset_reason;
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index da0c4c925350..6ab386ff3294 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -249,6 +249,11 @@ void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
 	mptcp_event(MPTCP_EVENT_SUB_PRIORITY, mptcp_sk(subflow->conn), sk, GFP_ATOMIC);
 }
 
+void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
+{
+	pr_debug("fail_seq=%llu", fail_seq);
+}
+
 /* path manager helpers */
 
 bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, struct sk_buff *skb,
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 3e4a79cf520a..9ee5676e70c6 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -140,6 +140,7 @@ struct mptcp_options_received {
 		add_addr : 1,
 		rm_addr : 1,
 		mp_prio : 1,
+		mp_fail : 1,
 		echo : 1,
 		csum_reqd : 1,
 		backup : 1,
@@ -161,6 +162,7 @@ struct mptcp_options_received {
 	u64	ahmac;
 	u8	reset_reason:4;
 	u8	reset_transient:1;
+	u64	fail_seq;
 };
 
 static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
@@ -726,6 +728,7 @@ void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup);
 int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 				 struct mptcp_addr_info *addr,
 				 u8 bkup);
+void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq);
 void mptcp_pm_free_anno_list(struct mptcp_sock *msk);
 bool mptcp_pm_sport_in_anno_list(struct mptcp_sock *msk, const struct sock *sk);
 struct mptcp_pm_add_entry *
-- 
2.33.0

[PATCH net-next 5/7] mptcp: send out MP_FAIL when data checksum fails

[Mat Martineau]

From: Geliang Tang <geliangtang@xiaomi.com>

When a bad checksum is detected, set the send_mp_fail flag to send out
the MP_FAIL option.

Add a new function mptcp_has_another_subflow() to check whether there's
only a single subflow.

When multiple subflows are in use, close the affected subflow with a RST
that includes an MP_FAIL option and discard the data with the bad
checksum.

Set the sk_state of the subsocket to TCP_CLOSE, then the flag
MPTCP_WORK_CLOSE_SUBFLOW will be set in subflow_sched_work_if_closed,
and the subflow will be closed.

When a single subfow is in use, temporarily handled by sending MP_FAIL
with a RST too.

Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/protocol.h | 13 +++++++++++++
 net/mptcp/subflow.c  | 15 +++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 9ee5676e70c6..57a50b1194a9 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -614,6 +614,19 @@ static inline void mptcp_subflow_tcp_fallback(struct sock *sk,
 	inet_csk(sk)->icsk_af_ops = ctx->icsk_af_ops;
 }
 
+static inline bool mptcp_has_another_subflow(struct sock *ssk)
+{
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk), *tmp;
+	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+
+	mptcp_for_each_subflow(msk, tmp) {
+		if (tmp != subflow)
+			return true;
+	}
+
+	return false;
+}
+
 void __init mptcp_proto_init(void);
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 int __init mptcp_proto_v6_init(void);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 8c43aa14897a..dba8ad700fb8 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -910,6 +910,7 @@ static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *
 	csum = csum_partial(&header, sizeof(header), subflow->map_data_csum);
 	if (unlikely(csum_fold(csum))) {
 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
+		subflow->send_mp_fail = 1;
 		return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
 	}
 
@@ -1157,6 +1158,20 @@ static bool subflow_check_data_avail(struct sock *ssk)
 
 fallback:
 	/* RFC 8684 section 3.7. */
+	if (subflow->send_mp_fail) {
+		if (mptcp_has_another_subflow(ssk)) {
+			while ((skb = skb_peek(&ssk->sk_receive_queue)))
+				sk_eat_skb(ssk, skb);
+		}
+		ssk->sk_err = EBADMSG;
+		tcp_set_state(ssk, TCP_CLOSE);
+		subflow->reset_transient = 0;
+		subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
+		tcp_send_active_reset(ssk, GFP_ATOMIC);
+		WRITE_ONCE(subflow->data_avail, 0);
+		return true;
+	}
+
 	if (subflow->mp_join || subflow->fully_established) {
 		/* fatal protocol error, close the socket.
 		 * subflow_error_report() will introduce the appropriate barriers
-- 
2.33.0

[PATCH net-next 6/7] mptcp: add the mibs for MP_FAIL

[Mat Martineau]

From: Geliang Tang <geliangtang@xiaomi.com>

This patch added the mibs for MP_FAIL: MPTCP_MIB_MPFAILTX and
MPTCP_MIB_MPFAILRX.

Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/mib.c     | 2 ++
 net/mptcp/mib.h     | 2 ++
 net/mptcp/options.c | 1 +
 net/mptcp/subflow.c | 1 +
 4 files changed, 6 insertions(+)

diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c
index 3a7c4e7b2d79..b21ff9be04c6 100644
--- a/net/mptcp/mib.c
+++ b/net/mptcp/mib.c
@@ -44,6 +44,8 @@ static const struct snmp_mib mptcp_snmp_list[] = {
 	SNMP_MIB_ITEM("RmSubflow", MPTCP_MIB_RMSUBFLOW),
 	SNMP_MIB_ITEM("MPPrioTx", MPTCP_MIB_MPPRIOTX),
 	SNMP_MIB_ITEM("MPPrioRx", MPTCP_MIB_MPPRIORX),
+	SNMP_MIB_ITEM("MPFailTx", MPTCP_MIB_MPFAILTX),
+	SNMP_MIB_ITEM("MPFailRx", MPTCP_MIB_MPFAILRX),
 	SNMP_MIB_ITEM("RcvPruned", MPTCP_MIB_RCVPRUNED),
 	SNMP_MIB_ITEM("SubflowStale", MPTCP_MIB_SUBFLOWSTALE),
 	SNMP_MIB_ITEM("SubflowRecover", MPTCP_MIB_SUBFLOWRECOVER),
diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h
index 8ec16c991aac..ecd3d8b117e0 100644
--- a/net/mptcp/mib.h
+++ b/net/mptcp/mib.h
@@ -37,6 +37,8 @@ enum linux_mptcp_mib_field {
 	MPTCP_MIB_RMSUBFLOW,		/* Remove a subflow */
 	MPTCP_MIB_MPPRIOTX,		/* Transmit a MP_PRIO */
 	MPTCP_MIB_MPPRIORX,		/* Received a MP_PRIO */
+	MPTCP_MIB_MPFAILTX,		/* Transmit a MP_FAIL */
+	MPTCP_MIB_MPFAILRX,		/* Received a MP_FAIL */
 	MPTCP_MIB_RCVPRUNED,		/* Incoming packet dropped due to memory limit */
 	MPTCP_MIB_SUBFLOWSTALE,		/* Subflows entered 'stale' status */
 	MPTCP_MIB_SUBFLOWRECOVER,	/* Subflows returned to active status after being stale */
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index fa287a49dc84..bec3ed82e253 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -1158,6 +1158,7 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 
 	if (mp_opt.mp_fail) {
 		mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq);
+		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX);
 		mp_opt.mp_fail = 0;
 	}
 
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index dba8ad700fb8..54b7ffc21861 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -911,6 +911,7 @@ static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *
 	if (unlikely(csum_fold(csum))) {
 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
 		subflow->send_mp_fail = 1;
+		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPFAILTX);
 		return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
 	}
 
-- 
2.33.0

[PATCH net-next 7/7] selftests: mptcp: add MP_FAIL mibs check

[Mat Martineau]

From: Geliang Tang <geliangtang@xiaomi.com>

This patch added a function chk_fail_nr to check the mibs for MP_FAIL.

Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 .../testing/selftests/net/mptcp/mptcp_join.sh | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 7b3e6cc56935..255793c5ac4f 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -578,6 +578,43 @@ chk_csum_nr()
 	fi
 }
 
+chk_fail_nr()
+{
+	local mp_fail_nr_tx=$1
+	local mp_fail_nr_rx=$2
+	local count
+	local dump_stats
+
+	printf "%-39s %s" " " "ftx"
+	count=`ip netns exec $ns1 nstat -as | grep MPTcpExtMPFailTx | awk '{print $2}'`
+	[ -z "$count" ] && count=0
+	if [ "$count" != "$mp_fail_nr_tx" ]; then
+		echo "[fail] got $count MP_FAIL[s] TX expected $mp_fail_nr_tx"
+		ret=1
+		dump_stats=1
+	else
+		echo -n "[ ok ]"
+	fi
+
+	echo -n " - frx   "
+	count=`ip netns exec $ns2 nstat -as | grep MPTcpExtMPFailRx | awk '{print $2}'`
+	[ -z "$count" ] && count=0
+	if [ "$count" != "$mp_fail_nr_rx" ]; then
+		echo "[fail] got $count MP_FAIL[s] RX expected $mp_fail_nr_rx"
+		ret=1
+		dump_stats=1
+	else
+		echo "[ ok ]"
+	fi
+
+	if [ "${dump_stats}" = 1 ]; then
+		echo Server ns stats
+		ip netns exec $ns1 nstat -as | grep MPTcp
+		echo Client ns stats
+		ip netns exec $ns2 nstat -as | grep MPTcp
+	fi
+}
+
 chk_join_nr()
 {
 	local msg="$1"
@@ -627,6 +664,7 @@ chk_join_nr()
 	fi
 	if [ $checksum -eq 1 ]; then
 		chk_csum_nr
+		chk_fail_nr 0 0
 	fi
 }
 
-- 
2.33.0

Re: [PATCH net-next 0/7] mptcp: Optimize output options and add MP_FAIL

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Tue, 24 Aug 2021 16:26:12 -0700 you wrote:
> This patch set contains two groups of changes that we've been testing in
> the MPTCP tree.
> 
> 
> The first optimizes the code path and data structure for populating
> MPTCP option headers when transmitting.
> 
> [...]

Here is the summary with links:
  - [net-next,1/7] mptcp: optimize out option generation
    https://git.kernel.org/netdev/net-next/c/1bff1e43a30e
  - [net-next,2/7] mptcp: shrink mptcp_out_options struct
    https://git.kernel.org/netdev/net-next/c/d7b269083786
  - [net-next,3/7] mptcp: MP_FAIL suboption sending
    https://git.kernel.org/netdev/net-next/c/c25aeb4e0953
  - [net-next,4/7] mptcp: MP_FAIL suboption receiving
    https://git.kernel.org/netdev/net-next/c/5580d41b758a
  - [net-next,5/7] mptcp: send out MP_FAIL when data checksum fails
    https://git.kernel.org/netdev/net-next/c/478d770008b0
  - [net-next,6/7] mptcp: add the mibs for MP_FAIL
    https://git.kernel.org/netdev/net-next/c/eb7f33654dc1
  - [net-next,7/7] selftests: mptcp: add MP_FAIL mibs check
    https://git.kernel.org/netdev/net-next/c/6bb3ab4913e9

You are awesome, thank you!
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