From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from chinatelecom.cn (prt-mail.chinatelecom.cn [42.123.76.223]) by smtp.subspace.kernel.org (Postfix) with ESMTP id DCA7D72 for ; Mon, 12 Jul 2021 09:53:25 +0000 (UTC) HMM_SOURCE_IP:172.18.0.218:58312.215717861 HMM_ATTACHE_NUM:0000 HMM_SOURCE_TYPE:SMTP Received: from clientip-36.111.140.26?logid-241e65843d0944bd8cb123133414a7f8 (unknown [172.18.0.218]) by chinatelecom.cn (HERMES) with SMTP id E9FE1280079; Mon, 12 Jul 2021 17:44:43 +0800 (CST) X-189-SAVE-TO-SEND: liyonglong@chinatelecom.cn Received: from ([172.18.0.218]) by app0025 with ESMTP id 241e65843d0944bd8cb123133414a7f8 for mptcp@lists.linux.dev; Mon Jul 12 17:44:42 2021 X-Transaction-ID: 241e65843d0944bd8cb123133414a7f8 X-filter-score: X-Real-From: liyonglong@chinatelecom.cn X-Receive-IP: 172.18.0.218 X-MEDUSA-Status: 0 Sender: liyonglong@chinatelecom.cn Subject: Re: [MPTCP][PATCH mptcp-next] Squash to "mptcp: build ADD_ADDR/echo-ADD_ADDR option according pm.add_signal" To: Geliang Tang Cc: mptcp@lists.linux.dev References: <9365b79b245b8a87af18ca458c67820d47de2515.1626016228.git.geliangtang@gmail.com> <80fa33a249c2ecc7edd9d0047dd84f163307cee7.1626016292.git.geliangtang@gmail.com> <347f6214-cc6b-2af2-c1e7-d9ac7f77f87e@chinatelecom.cn> <4f790fa7-f99e-401e-d266-8fd85921204a@chinatelecom.cn> <3f3c3065-8a08-fc0c-da8b-0e210097b136@chinatelecom.cn> From: Yonglong Li Message-ID: <847db51e-2941-776a-025a-874157c791d6@chinatelecom.cn> Date: Mon, 12 Jul 2021 17:44:39 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit On 2021/7/12 17:29, Geliang Tang wrote: > Yonglong Li 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 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 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 :) > > 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 >>>>>>> --- >>>>>>> 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