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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 15:33:28 +0800	[thread overview]
Message-ID: <CA+WQbwuTFxxzsbDdeiWgMN7iqUp9e-ubAmsLa7JpaZbQ+WSBBw@mail.gmail.com> (raw)
In-Reply-To: <347f6214-cc6b-2af2-c1e7-d9ac7f77f87e@chinatelecom.cn>

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?

> 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

  reply	other threads:[~2021-07-12  7:33 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 [this message]
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
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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