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From: Yonglong Li <liyonglong@chinatelecom.cn>
To: Geliang Tang <geliangtang@gmail.com>, 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 09:34:16 +0800	[thread overview]
Message-ID: <347f6214-cc6b-2af2-c1e7-d9ac7f77f87e@chinatelecom.cn> (raw)
In-Reply-To: <80fa33a249c2ecc7edd9d0047dd84f163307cee7.1626016292.git.geliangtang@gmail.com>



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.

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  1:52 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 [this message]
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
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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