From: Geliang Tang <geliangtang@gmail.com>
To: Yonglong Li <liyonglong@chinatelecom.cn>
Cc: mptcp@lists.linux.dev
Subject: Re: [MPTCP][PATCH mptcp-next] Squash to "mptcp: build ADD_ADDR/echo-ADD_ADDR option according pm.add_signal"
Date: Mon, 12 Jul 2021 17:29:12 +0800 [thread overview]
Message-ID: <CA+WQbwsq0LcQLxpbr+9adu68ButC2v5HhMpLyEy93FtKKOjD7w@mail.gmail.com> (raw)
In-Reply-To: <3f3c3065-8a08-fc0c-da8b-0e210097b136@chinatelecom.cn>
Yonglong Li <liyonglong@chinatelecom.cn> 于2021年7月12日周一 下午5:14写道:
>
>
>
> On 2021/7/12 16:44, Geliang Tang wrote:
> > Yonglong Li <liyonglong@chinatelecom.cn> 于2021年7月12日周一 下午4:07写道:
> >>
> >>
> >>
> >> On 2021/7/12 15:33, Geliang Tang wrote:
> >>> Hi Yonglong,
> >>>
> >>> Yonglong Li <liyonglong@chinatelecom.cn> 于2021年7月12日周一 上午9:34写道:
> >>>>
> >>>>
> >>>>
> >>>> On 2021/7/11 23:15, Geliang Tang wrote:
> >>>>> I think there're still some issues in v8:
> >>>>>
> >>>>> The remaining value is incorrect since "remaining += opt_size;" in the
> >>>>> "drop other suboptions" checks has been called twice in
> >>>>> mptcp_pm_add_addr_signal and mptcp_established_options_add_addr.
> >>>>>
> >>>> I think "remaining" in mptcp_pm_add_addr_signal does not touch "remaining" in
> >>>> mptcp_established_options_add_addr.
> >>>>
> >>>>> opts->local and opts->remote in mptcp_pm_add_addr_signal need be
> >>>>> populate after the length chech, not before the check.]
> >>>>>
> >>>>> The squash-to patch keeped the more orignal code unchanged, and just do
> >>>>> the least, necessary modifications.
> >>>>>
> >>>> Agree opts->local and opts->remote should be asigned after the length check.
> >>>> But if keep the length check out of mptcp_pm_add_addr_signal (out of pm lock )
> >>>> as orignal code, there is a race that:
> >>>>
> >>>> ==> a add addr event (pm.addr_signal == MPTCP_ADD_ADDR_SIGNAL)
> >>>> ==> call mptcp_pm_add_addr_signal
> >>>> ==> a echo add addr event trigger (pm.addr_signal == MPTCP_ADD_ADDR_ECHO|MPTCP_ADD_ADDR_SIGNAL)
> >>>> ==> at this time opts->remote is empty and the length is incorrect.
> >>>>
> >>>
> >>> What will happen in v8 when this race occurs? How dose v8 deal with the
> >>> race?
> >> Hi Geliang, thinks for your patience.
> >>
> >> I think v8 doesn't have this issue:
> >> ==> a add addr event (pm.addr_signal == MPTCP_ADD_ADDR_SIGNAL)
> >> ==> call mptcp_pm_add_addr_signal, save pm.addr_signal to add_addr and save addr in opts under pm.lock
> >> ==> a echo add addr event trigger (pm.addr_signal == MPTCP_ADD_ADDR_ECHO), but add_addr doesn't changed.
> >> ==> use add_addr and opts to check length.
> >> ==> next send ack process will deal with MPTCP_ADD_ADDR_ECHO event.
> >
> > Thanks for your explanation.
> >
> > I think this squash-to patch did the same thing:
> >
> > ==> an add addr event (pm.addr_signal == MPTCP_ADD_ADDR_SIGNAL)
> > ==> call mptcp_pm_add_addr_signal, save echo bit of pm.addr_signal to
> > 'echo' (echo = false), save the port number to 'port', and save addr
> > in opts under pm.lock
> > ==> an echo add addr event trigger (pm.addr_signal ==
> > MPTCP_ADD_ADDR_ECHO), but 'echo' and 'port' don't changed.
> > ==> use 'echo' to get the address family, use 'family', 'echo' and
> > 'port' to check length.
> > ==> next send ack process will deal with MPTCP_ADD_ADDR_ECHO event.
> >
> > Do you think so?
> yep. In this case the squash-to patch is ok. But I think between "drop other suboptions" checks and
> mptcp_pm_add_addr_signal the race still exist.
>
I think this is easy to fix:
Add a new argument "drop_other_suboptions" for mptcp_pm_add_addr_signal,
move this "drop other suboptions" check code into mptcp_pm_add_addr_signal,
I'll sent a v2 later.
Thanks,
-Geliang
> ==> an add addr event (pm.addr_signal == MPTCP_ADD_ADDR_SIGNAL)
> ==> "drop other suboptions" checks will use MPTCP_ADD_ADDR_SIGNAL to check
> ==> an echo add addr event trigger (pm.addr_signal == MPTCP_ADD_ADDR_SIGNAL | MPTCP_ADD_ADDR_ECHO )
> ==> call mptcp_pm_add_addr_signal, MPTCP_ADD_ADDR_ECHO will be clear in pm.addr_signal
> ==> process MPTCP_ADD_ADDR_ECHO event.
>
> WDYT?
>
> >
> >>
> >>>
> >>>> So I think the orignal code is incorrect. WDYT?
> >>>>
> >>>>> Drop the "drop other suboptions" check in mptcp_pm_add_addr_signal.
> >>>>>
> >>>>> Change arguments of mptcp_pm_add_addr_signal.
> >>>>>
> >>>>> Keep mptcp_add_addr_len unchanged.
> >>>>>
> >>>>> Signed-off-by: Geliang Tang <geliangtang@gmail.com>
> >>>>> ---
> >>>>> net/mptcp/options.c | 35 +++++++++++++++++------------------
> >>>>> net/mptcp/pm.c | 23 +++++++++--------------
> >>>>> net/mptcp/protocol.h | 27 +++++++++------------------
> >>>>> 3 files changed, 35 insertions(+), 50 deletions(-)
> >>>>>
> >>>>> diff --git a/net/mptcp/options.c b/net/mptcp/options.c
> >>>>> index 5c0ad9b90866..93ad7b134f74 100644
> >>>>> --- a/net/mptcp/options.c
> >>>>> +++ b/net/mptcp/options.c
> >>>>> @@ -663,16 +663,14 @@ static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *
> >>>>> struct mptcp_sock *msk = mptcp_sk(subflow->conn);
> >>>>> bool drop_other_suboptions = false;
> >>>>> unsigned int opt_size = *size;
> >>>>> - u8 add_addr;
> >>>>> + bool echo;
> >>>>> + bool port;
> >>>>> + u8 family;
> >>>>> int len;
> >>>>>
> >>>>> - if (!mptcp_pm_should_add_signal(msk) ||
> >>>>> - !mptcp_pm_add_addr_signal(msk, skb, opt_size, remaining, opts, &add_addr))
> >>>>> - return false;
> >>>>> -
> >>>>> - if (((add_addr & BIT(MPTCP_ADD_ADDR_ECHO)) ||
> >>>>> - ((add_addr & BIT(MPTCP_ADD_ADDR_SIGNAL)) &&
> >>>>> - (opts->local.family == AF_INET6 || opts->local.port))) &&
> >>>>> + if ((mptcp_pm_should_add_signal_echo(msk) ||
> >>>>> + (mptcp_pm_should_add_signal_addr(msk) &&
> >>>>> + (msk->pm.local.family == AF_INET6 || msk->pm.local.port))) &&
> >>>>> skb && skb_is_tcp_pure_ack(skb)) {
> >>>>> pr_debug("drop other suboptions");
> >>>>> opts->suboptions = 0;
> >>>>> @@ -682,7 +680,12 @@ static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *
> >>>>> drop_other_suboptions = true;
> >>>>> }
> >>>>>
> >>>>> - len = mptcp_add_addr_len(opts, add_addr);
> >>>>> + if (!mptcp_pm_should_add_signal(msk) ||
> >>>>> + !mptcp_pm_add_addr_signal(msk, remaining, &opts->local, &opts->remote, &echo, &port))
> >>>>> + return false;
> >>>>> +
> >>>>> + family = echo ? opts->remote.family : opts->local.family;
> >>>>> + len = mptcp_add_addr_len(family, echo, port);
> >>>>> if (remaining < len)
> >>>>> return false;
> >>>>>
> >>>>> @@ -690,15 +693,14 @@ static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *
> >>>>> if (drop_other_suboptions)
> >>>>> *size -= opt_size;
> >>>>> opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
> >>>>> - if (!(add_addr & BIT(MPTCP_ADD_ADDR_ECHO)) &&
> >>>>> - (add_addr & BIT(MPTCP_ADD_ADDR_SIGNAL))) {
> >>>>> + if (!echo) {
> >>>>> opts->ahmac = add_addr_generate_hmac(msk->local_key,
> >>>>> msk->remote_key,
> >>>>> &opts->local);
> >>>>> }
> >>>>> - pr_debug("addr_signal:%x, echo=%d, local_addr_id=%d, ahmac=%llu, local_port=%d, remote_addr_id=%d, remote_port=%d",
> >>>>> - add_addr, (opts->ahmac == 0), opts->local.id, opts->ahmac,
> >>>>> - ntohs(opts->local.port), opts->remote.id, ntohs(opts->remote.port));
> >>>>> + pr_debug("local_id=%d, local_port=%d, remote_id=%d, remote_port=%d, ahmac=%llu, echo=%d",
> >>>>> + opts->local.id, ntohs(opts->local.port), opts->remote.id,
> >>>>> + ntohs(opts->remote.port), opts->ahmac, echo);
> >>>>>
> >>>>> return true;
> >>>>> }
> >>>>> @@ -1253,13 +1255,10 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
> >>>>>
> >>>>> mp_capable_done:
> >>>>> if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
> >>>>> - struct mptcp_addr_info *addr = &opts->remote;
> >>>>> + struct mptcp_addr_info *addr = opts->ahmac ? &opts->local : &opts->remote;
> >>>>> u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
> >>>>> u8 echo = MPTCP_ADDR_ECHO;
> >>>>>
> >>>>> - if (opts->ahmac)
> >>>>> - addr = &opts->local;
> >>>>> -
> >>>>> #if IS_ENABLED(CONFIG_MPTCP_IPV6)
> >>>>> if (addr->family == AF_INET6)
> >>>>> len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
> >>>>> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> >>>>> index 264f522af530..399b59cb7563 100644
> >>>>> --- a/net/mptcp/pm.c
> >>>>> +++ b/net/mptcp/pm.c
> >>>>> @@ -253,12 +253,13 @@ void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
> >>>>>
> >>>>> /* path manager helpers */
> >>>>>
> >>>>> -bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, struct sk_buff *skb,
> >>>>> - unsigned int opt_size, unsigned int remaining,
> >>>>> - struct mptcp_out_options *opts, u8 *add_addr)
> >>>>> +bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
> >>>>> + struct mptcp_addr_info *saddr, struct mptcp_addr_info *daddr,
> >>>>> + bool *echo, bool *port)
> >>>>> {
> >>>>> int ret = false;
> >>>>> u8 add_addr;
> >>>>> + u8 family;
> >>>>>
> >>>>> spin_lock_bh(&msk->pm.lock);
> >>>>>
> >>>>> @@ -266,21 +267,15 @@ bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, struct sk_buff *skb,
> >>>>> if (!mptcp_pm_should_add_signal(msk))
> >>>>> goto out_unlock;
> >>>>>
> >>>>> - opts->local = msk->pm.local;
> >>>>> - opts->remote = msk->pm.remote;
> >>>>> - *add_addr = msk->pm.addr_signal;
> >>>>> + *echo = mptcp_pm_should_add_signal_echo(msk);
> >>>>> + *port = !!(*echo ? msk->pm.remote.port : msk->pm.local.port);
> >>>>>
> >>>>> - if (((msk->pm.addr_signal & BIT(MPTCP_ADD_ADDR_ECHO)) ||
> >>>>> - ((msk->pm.addr_signal & BIT(MPTCP_ADD_ADDR_SIGNAL)) &&
> >>>>> - (msk->pm.local.family == AF_INET6 || msk->pm.local.port))) &&
> >>>>> - skb && skb_is_tcp_pure_ack(skb)) {
> >>>>> - remaining += opt_size;
> >>>>> - }
> >>>>> -
> >>>>> - if (remaining < mptcp_add_addr_len(opts, *add_addr))
> >>>>> + family = *echo ? msk->pm.remote.family : msk->pm.local.family;
> >>>>> + if (remaining < mptcp_add_addr_len(family, *echo, *port))
> >>>>> goto out_unlock;
> >>>>>
> >>>>> *saddr = msk->pm.local;
> >>>>> + *daddr = msk->pm.remote;
> >>>>> add_addr = READ_ONCE(msk->pm.addr_signal);
> >>>>> if (mptcp_pm_should_add_signal_echo(msk))
> >>>>> add_addr &= ~BIT(MPTCP_ADD_ADDR_ECHO);
> >>>>> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
> >>>>> index 937e0309e340..4b63cc6079fa 100644
> >>>>> --- a/net/mptcp/protocol.h
> >>>>> +++ b/net/mptcp/protocol.h
> >>>>> @@ -766,25 +766,16 @@ static inline bool mptcp_pm_should_rm_signal(struct mptcp_sock *msk)
> >>>>> return READ_ONCE(msk->pm.addr_signal) & BIT(MPTCP_RM_ADDR_SIGNAL);
> >>>>> }
> >>>>>
> >>>>> -static inline unsigned int mptcp_add_addr_len(struct mptcp_out_options *opts,
> >>>>> - u8 add_addr)
> >>>>> +static inline unsigned int mptcp_add_addr_len(int family, bool echo, bool port)
> >>>>> {
> >>>>> - struct mptcp_addr_info *addr = &opts->remote;
> >>>>> - u8 len = 0;
> >>>>> + u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
> >>>>>
> >>>>> - if (!(add_addr & BIT(MPTCP_ADD_ADDR_ECHO)) &&
> >>>>> - (add_addr & BIT(MPTCP_ADD_ADDR_SIGNAL))) {
> >>>>> - addr = &opts->local;
> >>>>> + if (family == AF_INET6)
> >>>>> + len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
> >>>>> + if (!echo)
> >>>>> len += MPTCPOPT_THMAC_LEN;
> >>>>> - }
> >>>>> -
> >>>>> - if (addr->family == AF_INET6)
> >>>>> - len += TCPOLEN_MPTCP_ADD_ADDR6_BASE;
> >>>>> - else
> >>>>> - len += TCPOLEN_MPTCP_ADD_ADDR_BASE;
> >>>>> -
> >>>>> /* account for 2 trailing 'nop' options */
> >>>>> - if (addr->port)
> >>>>> + if (port)
> >>>>> len += TCPOLEN_MPTCP_PORT_LEN + TCPOLEN_MPTCP_PORT_ALIGN;
> >>>>>
> >>>>> return len;
> >>>>> @@ -798,9 +789,9 @@ static inline int mptcp_rm_addr_len(const struct mptcp_rm_list *rm_list)
> >>>>> return TCPOLEN_MPTCP_RM_ADDR_BASE + roundup(rm_list->nr - 1, 4) + 1;
> >>>>> }
> >>>>>
> >>>>> -bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, struct sk_buff *skb,
> >>>>> - unsigned int opt_size, unsigned int remaining,
> >>>>> - struct mptcp_out_options *opts, u8 *add_addr);
> >>>>> +bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
> >>>>> + struct mptcp_addr_info *saddr, struct mptcp_addr_info *daddr,
> >>>>> + bool *echo, bool *port);
> >>>>> bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
> >>>>> struct mptcp_rm_list *rm_list);
> >>>>> int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
> >>>>>
> >>>>
> >>>> --
> >>>> Li YongLong
> >>>
> >>
> >> --
> >> Li YongLong
> >
> >
>
> --
> Li YongLong
next prev parent reply other threads:[~2021-07-12 9:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-11 15:15 [MPTCP][PATCH mptcp-next] Squash to "mptcp: make MPTCP_ADD_ADDR_SIGNAL and MPTCP_ADD_ADDR_ECHO separate" Geliang Tang
2021-07-11 15:15 ` [MPTCP][PATCH mptcp-next] Squash to "mptcp: fix ADD_ADDR and RM_ADDR maybe flush addr_signal each other" Geliang Tang
2021-07-12 9:55 ` Yonglong Li
2021-07-12 10:34 ` Geliang Tang
2021-07-12 22:27 ` Mat Martineau
2021-07-11 15:15 ` [MPTCP][PATCH mptcp-next] Squash to "mptcp: build ADD_ADDR/echo-ADD_ADDR option according pm.add_signal" Geliang Tang
2021-07-12 1:34 ` Yonglong Li
2021-07-12 7:33 ` Geliang Tang
2021-07-12 8:06 ` Yonglong Li
2021-07-12 8:44 ` Geliang Tang
2021-07-12 9:07 ` Geliang Tang
2021-07-12 9:21 ` Yonglong Li
2021-07-12 9:14 ` Yonglong Li
2021-07-12 9:29 ` Geliang Tang [this message]
2021-07-12 9:44 ` Yonglong Li
2021-07-12 10:34 ` Geliang Tang
2021-07-12 22:10 ` [MPTCP][PATCH mptcp-next] Squash to "mptcp: make MPTCP_ADD_ADDR_SIGNAL and MPTCP_ADD_ADDR_ECHO separate" Mat Martineau
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