net/mptcp/options.c | 6 +++--- net/mptcp/protocol.h | 44 +++++++++++++++++++++++++++++--------------- 2 files changed, 32 insertions(+), 18 deletions(-)
From: Quanye Yang <quanyeyang@proton.me>
struct mptcp_options_received is allocated on the stack while parsing
incoming MPTCP options. Several suboptions are mutually exclusive, as
enforced by mptcp_parse_option(), so their payloads can overlap.
Group fields by suboption and place the mutually exclusive payloads in
an anonymous union: MP_CAPABLE keys, MP_JOIN, ADD_ADDR, MP_FAIL and
MP_FASTCLOSE. Keep DSS and rm_list outside the union: they can be
combined with other suboptions. Split the former shared rcvr_key into
rcvr_key (MP_CAPABLE) and fc_recv_key (MP_FASTCLOSE). Move join_id into
the MP_JOIN group, and overlap token, thmac and hmac inside that group.
Further shrinking would require changing the parser so currently
coexisting fields (DSS mapping vs ACK, rm_list, status flags) can
overlap. That adds complexity for little gain, since the outer union is
already dominated by the MP_JOIN / ADD_ADDR members.
This reduces the structure size from 136 to 72 bytes on x86_64.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/625
Signed-off-by: Quanye Yang <quanyeyang@proton.me>
---
Changes in v2:
- Group fields by suboption and move join_id into the MP_JOIN group
- Split rcvr_key into rcvr_key (MP_CAPABLE) and fc_recv_key (MP_FASTCLOSE)
- Overlap MP_JOIN token, thmac and hmac
- Drop the dependency on the invalid-option series
- Link to v1: https://patch.msgid.link/20260904-mptcp-shrink-opt-rx-v1-1-2d87ab9505ff@proton.me
---
net/mptcp/options.c | 6 +++---
net/mptcp/protocol.h | 44 +++++++++++++++++++++++++++++---------------
2 files changed, 32 insertions(+), 18 deletions(-)
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index f87707110c75..943b2b37eaae 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -374,10 +374,10 @@ static void mptcp_parse_option(const struct sk_buff *skb,
break;
ptr += 2;
- mp_opt->rcvr_key = get_unaligned_be64(ptr);
+ mp_opt->fc_recv_key = get_unaligned_be64(ptr);
ptr += 8;
mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE;
- pr_debug("MP_FASTCLOSE: recv_key=%llu\n", mp_opt->rcvr_key);
+ pr_debug("MP_FASTCLOSE: fc_recv_key=%llu\n", mp_opt->fc_recv_key);
break;
case MPTCPOPT_RST:
@@ -1259,7 +1259,7 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) {
if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) &&
- READ_ONCE(msk->local_key) == mp_opt.rcvr_key) {
+ READ_ONCE(msk->local_key) == mp_opt.fc_recv_key) {
WRITE_ONCE(msk->rcv_fastclose, true);
mptcp_schedule_work((struct sock *)msk);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index b3121c8c766b..11adb2d67bb6 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -145,13 +145,13 @@ static inline bool before64(__u64 seq1, __u64 seq2)
#define after64(seq2, seq1) before64(seq1, seq2)
struct mptcp_options_received {
- u64 sndr_key;
- u64 rcvr_key;
- u64 data_ack;
- u64 data_seq;
- u32 subflow_seq;
- u16 data_len;
- __sum16 csum;
+ struct { /* DSS, also used by MP_CAPABLE with data */
+ u64 data_ack;
+ u64 data_seq;
+ u32 subflow_seq;
+ u16 data_len;
+ __sum16 csum;
+ };
struct_group(status,
u16 suboptions;
u16 use_map:1,
@@ -167,15 +167,29 @@ struct mptcp_options_received {
deny_join_id0:1,
__unused:2;
);
- u8 join_id;
- u32 token;
- u32 nonce;
- u64 thmac;
- u8 hmac[MPTCPOPT_HMAC_LEN];
- struct mptcp_addr_info addr;
struct mptcp_rm_list rm_list;
- u64 ahmac;
- u64 fail_seq;
+ /* Options below are mutually exclusive, see mptcp_parse_option() */
+ union {
+ struct {
+ u64 sndr_key;
+ u64 rcvr_key;
+ };
+ struct {
+ u32 nonce;
+ u8 join_id;
+ union {
+ u32 token;
+ u64 thmac;
+ u8 hmac[MPTCPOPT_HMAC_LEN];
+ };
+ };
+ struct {
+ struct mptcp_addr_info addr;
+ u64 ahmac;
+ };
+ u64 fail_seq;
+ u64 fc_recv_key;
+ };
};
static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
---
base-commit: d5a4e55ccfb893614646d0f0e5c440daa92b7467
change-id: 20260904-mptcp-shrink-opt-rx-v2-d8e0c6951294
Best regards,
--
Quanye Yang <quanyeyang@proton.me>Hi Quanye,
Thank you for your modifications, that's great!
Our CI did some validations and here is its report:
- KVM Validation: normal (except selftest_mptcp_join): Success! ✅
- KVM Validation: normal (only selftest_mptcp_join): Success! ✅
- KVM Validation: debug (except selftest_mptcp_join): Success! ✅
- KVM Validation: debug (only selftest_mptcp_join): Success! ✅
- KVM Validation: btf-normal (only bpftest_all): Success! ✅
- KVM Validation: btf-debug (only bpftest_all): Success! ✅
- Perf:
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/33869151432
Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/a98754ba79b7
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1157920
If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:
$ cd [kernel source code]
$ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
--pull always mptcp/mptcp-upstream-virtme-docker:latest \
auto-normal
For more details:
https://github.com/multipath-tcp/mptcp-upstream-virtme-docker
Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)
Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)
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