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Message-ID: <CADvbK_ejiW3WKg66=FLD9v5jFh8BjzDsvopyJ5kr02jsZw-_0w@mail.gmail.com>
Date: Tue, 6 Mar 2018 15:03:13 +0800
From: Xin Long <lucien.xin@...il.com>
To: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc: network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
Neil Horman <nhorman@...driver.com>,
davem <davem@...emloft.net>
Subject: Re: [PATCH net-next 2/3] sctp: add support for SCTP_DSTADDRV4/6
Information for sendmsg
On Tue, Mar 6, 2018 at 7:39 AM, Marcelo Ricardo Leitner
<marcelo.leitner@...il.com> wrote:
> On Mon, Mar 05, 2018 at 08:44:19PM +0800, Xin Long wrote:
>> This patch is to add support for Destination IPv4/6 Address options
>> for sendmsg, as described in section 5.3.9/10 of RFC6458.
>>
>> With this option, you can provide more than one destination addrs
>> to sendmsg when creating asoc, like sctp_connectx.
>>
>> It's also a necessary send info for sctp_sendv.
>>
>> Signed-off-by: Xin Long <lucien.xin@...il.com>
>> ---
>> include/net/sctp/structs.h | 1 +
>> include/uapi/linux/sctp.h | 6 ++++
>> net/sctp/socket.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 84 insertions(+)
>>
>> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
>> index d40a2a3..ec6e46b 100644
>> --- a/include/net/sctp/structs.h
>> +++ b/include/net/sctp/structs.h
>> @@ -2113,6 +2113,7 @@ struct sctp_cmsgs {
>> struct sctp_sndrcvinfo *srinfo;
>> struct sctp_sndinfo *sinfo;
>> struct sctp_prinfo *prinfo;
>> + struct msghdr *addrs_msg;
>> };
>>
>> /* Structure for tracking memory objects */
>> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
>> index 0dd1f82..a1bc350 100644
>> --- a/include/uapi/linux/sctp.h
>> +++ b/include/uapi/linux/sctp.h
>> @@ -308,6 +308,12 @@ typedef enum sctp_cmsg_type {
>> #define SCTP_NXTINFO SCTP_NXTINFO
>> SCTP_PRINFO, /* 5.3.7 SCTP PR-SCTP Information Structure */
>> #define SCTP_PRINFO SCTP_PRINFO
>> + SCTP_AUTHINFO, /* 5.3.8 SCTP AUTH Information Structure (RESERVED) */
>> +#define SCTP_AUTHINFO SCTP_AUTHINFO
>> + SCTP_DSTADDRV4, /* 5.3.9 SCTP Destination IPv4 Address Structure */
>> +#define SCTP_DSTADDRV4 SCTP_DSTADDRV4
>> + SCTP_DSTADDRV6, /* 5.3.10 SCTP Destination IPv6 Address Structure */
>> +#define SCTP_DSTADDRV6 SCTP_DSTADDRV6
>> } sctp_cmsg_t;
>>
>> /*
>> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
>> index fdde697..067b57a 100644
>> --- a/net/sctp/socket.c
>> +++ b/net/sctp/socket.c
>> @@ -1676,6 +1676,7 @@ static int sctp_sendmsg_new_asoc(struct sock *sk, __u16 sflags,
>> struct net *net = sock_net(sk);
>> struct sctp_association *asoc;
>> enum sctp_scope scope;
>> + struct cmsghdr *cmsg;
>> int err = -EINVAL;
>>
>> *tp = NULL;
>> @@ -1741,6 +1742,67 @@ static int sctp_sendmsg_new_asoc(struct sock *sk, __u16 sflags,
>> goto free;
>> }
>>
>> + if (!cmsgs->addrs_msg)
>> + return 0;
>> +
>> + /* sendv addr list parse */
>> + for_each_cmsghdr(cmsg, cmsgs->addrs_msg) {
>> + struct sctp_transport *transport;
>> + struct sctp_association *old;
>> + union sctp_addr _daddr;
>> + int dlen;
>> +
>> + if (cmsg->cmsg_level != IPPROTO_SCTP ||
>> + (cmsg->cmsg_type != SCTP_DSTADDRV4 &&
>> + cmsg->cmsg_type != SCTP_DSTADDRV6))
>> + continue;
>> +
>> + daddr = &_daddr;
>> + memset(daddr, 0, sizeof(*daddr));
>> + dlen = cmsg->cmsg_len - sizeof(struct cmsghdr);
>> + if (cmsg->cmsg_type == SCTP_DSTADDRV4) {
>> + if (dlen < sizeof(struct in_addr))
>> + goto free;
>> +
>> + dlen = sizeof(struct in_addr);
>> + daddr->v4.sin_family = AF_INET;
>> + daddr->v4.sin_port = htons(asoc->peer.port);
>> + memcpy(&daddr->v4.sin_addr, CMSG_DATA(cmsg), dlen);
>> + } else {
>> + if (dlen < sizeof(struct in6_addr))
>> + goto free;
>> +
>> + dlen = sizeof(struct in6_addr);
>> + daddr->v6.sin6_family = AF_INET6;
>> + daddr->v6.sin6_port = htons(asoc->peer.port);
>> + memcpy(&daddr->v6.sin6_addr, CMSG_DATA(cmsg), dlen);
>> + }
>> + err = sctp_verify_addr(sk, daddr, sizeof(*daddr));
>> + if (err)
>> + goto free;
>> +
>> + old = sctp_endpoint_lookup_assoc(ep, daddr, &transport);
>> + if (old && old != asoc) {
>> + if (old->state >= SCTP_STATE_ESTABLISHED)
>> + err = -EISCONN;
>> + else
>> + err = -EALREADY;
>> + goto free;
>> + }
>> +
>> + if (sctp_endpoint_is_peeled_off(ep, daddr)) {
>> + err = -EADDRNOTAVAIL;
>> + goto free;
>> + }
>> +
>> + transport = sctp_assoc_add_peer(asoc, daddr, GFP_KERNEL,
>> + SCTP_UNKNOWN);
>> + if (!transport) {
>> + err = -ENOMEM;
>> + goto free;
>> + }
>> + }
>> +
>> return 0;
>>
>> free:
>> @@ -7778,6 +7840,21 @@ static int sctp_msghdr_parse(const struct msghdr *msg, struct sctp_cmsgs *cmsgs)
>> if (cmsgs->prinfo->pr_policy == SCTP_PR_SCTP_NONE)
>> cmsgs->prinfo->pr_value = 0;
>> break;
>> + case SCTP_DSTADDRV4:
>> + case SCTP_DSTADDRV6:
>> + /* SCTP Socket API Extension
>> + * 5.3.9/10 SCTP Destination IPv4/6 Address Structure (SCTP_DSTADDRV4/6)
>> + *
>> + * This cmsghdr structure specifies SCTP options for sendmsg().
>> + *
>> + * cmsg_level cmsg_type cmsg_data[]
>> + * ------------ ------------ ---------------------
>> + * IPPROTO_SCTP SCTP_DSTADDRV4 struct in_addr
>> + * ------------ ------------ ---------------------
>> + * IPPROTO_SCTP SCTP_DSTADDRV6 struct in6_addr
>> + */
>> + cmsgs->addrs_msg = my_msg;
>
> I think this is being handled differently from what the RFC specifies.
> AFAIU the rfc defines these two options being each one an array of a
> specific element type, in_addr and in6_addr.
Hi, Marcelo.
>From section 5.3.9 of RFC6458:
This ancillary data can be used to provide more than one destination
address to sendmsg(). It can be used to implement sctp_sendv() using
sendmsg().
It doesn't say to put "more than one destination address" into an array of
one option, or put "more than one destination address" into many options.
I was also confused, then I checked sctp_process_cmsgs_for_init() in
freebsd, I think it's in MANY options.
>
> The patch is saving both options into a single pointer, which later is
> processed as a list of (in_addr or in6_addr) elements.
It's not, 'my_msg' is the whole msghdr, not only in_addr or in6_addr.
later in sctp_sendmsg_new_asoc, it will parse this msghdr again but
this time only to pick up SCTP_DSTADDRV4/6 options.
(by this way I don't need to alloc list or array to save them)
Note that: one option is just one address, NOT a list of addresses.
like, it can even be:
SCTP_DSTADDRV4 (one option)
SCTP_DSTADDRV6 (one option)
SCTP_DSTADDRV4 (one option)
SCTP_DSTADDRV4 (one option)
SCTP_DSTADDRV6 (one option)
Maybe the name of cmsgs->addrs_msg is confusing here, but I
actually think it as a flag to see if there is addrs info in the msghdr,
and also as a parameter to pass the msghdr into sctp_sendmsg_new_asoc.
>
> If an application specifies both options, each with a list of its own
> addresses, it will ignore one of the options.
If an application specifies many options, some are SCTP_DSTADDRV4
and some are SCTP_DSTADDRV6, none of them will be ignored in
sctp_sendmsg_new_asoc().
>
>> + break;
>> default:
>> return -EINVAL;
>> }
>> --
>> 2.1.0
>>
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