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mptcp: pm: avoid computing add_addr size twice

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mptcp_add_addr_len helper was called twice: in mptcp_pm_add_addr_signal,
then just after in mptcp_established_options_add_addr. Both to check
the remaining space.

The second call is not needed: if there is not enough space,
mptcp_pm_add_addr_signal will return false, and the caller,
mptcp_established_options_add_addr, will do the same without re-checking
the size again. Instead, mptcp_pm_add_addr_signal can directly set the
size.

Note that the returned size can be negative when other suboptions are
dropped, e.g. to send an echo ADD_ADDR with a v4 address, and no port.

While at it:

 - move mptcp_add_addr_len to pm.c, as it is now only used from there

 - use 'int' in mptcp_add_addr_len for the size, instead of having a mix

 - use a bool for 'ret' in mptcp_pm_add_addr_signal

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260605-net-next-mptcp-add-addr6-port-ts-v2-3-758e7ca73f4d@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Matthieu Baerts (NGI0) 2026-06-05 19:21:47 +10:00 committed by Jakub Kicinski
parent a8bffec089
commit 06c62385be
3 changed files with 25 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
net/mptcp/options.c
View File

@ -663,10 +663,8 @@ static bool mptcp_established_options_add_addr(struct sock *sk,
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
unsigned int opt_size = *size;
struct mptcp_addr_info addr;
bool echo;
int len;
/* add addr will strip the existing options, be sure to avoid breaking
* MPC/MPJ handshakes
@ -674,21 +672,12 @@ static bool mptcp_established_options_add_addr(struct sock *sk,
if (!mptcp_pm_should_add_signal(msk) ||
(opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) ||
!skb || !skb_is_tcp_pure_ack(skb) ||
!mptcp_pm_add_addr_signal(msk, opt_size, remaining, &addr, &echo))
!mptcp_pm_add_addr_signal(msk, size, remaining, &addr, &echo))
return false;
remaining += opt_size;
len = mptcp_add_addr_len(addr.family, echo, !!addr.port);
if (remaining < len)
return false;
*size = len;
pr_debug("drop other suboptions\n");
opts->suboptions = 0;
*size -= opt_size;
opts->suboptions = OPTION_MPTCP_ADD_ADDR;
opts->addr = addr;
opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
if (!echo) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDRTX);
opts->ahmac = add_addr_generate_hmac(READ_ONCE(msk->local_key),

27
net/mptcp/pm.c
View File

@ -887,13 +887,28 @@ void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
}
}
bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int opt_size,
unsigned int remaining,
static int mptcp_add_addr_len(int family, bool echo, bool port)
{
int len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
if (family == AF_INET6)
len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
if (!echo)
len += MPTCPOPT_THMAC_LEN;
/* account for 2 trailing 'nop' options */
if (port)
len += TCPOLEN_MPTCP_PORT_LEN + TCPOLEN_MPTCP_PORT_ALIGN;
return len;
}
bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, int *size, int remaining,
struct mptcp_addr_info *addr, bool *echo)
{
bool skip_add_addr = false;
int ret = false;
bool ret = false;
u8 add_addr;
int len = 0;
u8 family;
bool port;
@ -907,7 +922,7 @@ bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int opt_size,
* plain dup-ack from TCP perspective. The other MPTCP-relevant info,
* if any, will be carried by the 'original' TCP ack
*/
remaining += opt_size;
len -= *size;
*echo = mptcp_pm_should_add_signal_echo(msk);
if (*echo) {
@ -922,7 +937,8 @@ bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int opt_size,
family = msk->pm.local.family;
}
if (remaining < mptcp_add_addr_len(family, *echo, port)) {
len += mptcp_add_addr_len(family, *echo, port);
if (len > remaining) {
struct net *net = sock_net((struct sock *)msk);
if (*echo) {
@ -935,6 +951,7 @@ bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int opt_size,
}
ret = true;
*size = len;
drop_signal_mark:
WRITE_ONCE(msk->pm.addr_signal, add_addr);

18
net/mptcp/protocol.h
View File

@ -1206,23 +1206,7 @@ static inline bool mptcp_pm_is_kernel(const struct mptcp_sock *msk)
return READ_ONCE(msk->pm.pm_type) == MPTCP_PM_TYPE_KERNEL;
}
static inline unsigned int mptcp_add_addr_len(int family, bool echo, bool port)
{
u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
if (family == AF_INET6)
len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
if (!echo)
len += MPTCPOPT_THMAC_LEN;
/* account for 2 trailing 'nop' options */
if (port)
len += TCPOLEN_MPTCP_PORT_LEN + TCPOLEN_MPTCP_PORT_ALIGN;
return len;
}
bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int opt_size,
unsigned int remaining,
bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, int *size, int remaining,
struct mptcp_addr_info *addr, bool *echo);
bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
struct mptcp_rm_list *rm_list, int *len);