Re: [MPTCP][PATCH mptcp-next] Squash to "mptcp: build ADD_ADDR/echo-ADD_ADDR option according pm.add_signal"

[Geliang Tang <geliangtang@gmail.com>]

Yonglong Li <liyonglong@chinatelecom.cn> 于2021年7月12日周一 下午5:44写道：
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>
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> On 2021/7/12 17:29, Geliang Tang wrote:
> > 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. And the v8 do the same thing. Why not use v8 directly :)
>

You'll see the difference 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
> >
>
> --
> Li YongLong