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net: sctp: implement rfc6458, 5.3.4. SCTP_SNDINFO cmsg support
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This patch implements section 5.3.4. of RFC6458, that is, support
for 'SCTP Send Information Structure' (SCTP_SNDINFO) which can be
placed into ancillary data cmsghdr structure for sendmsg() calls.

The sctp_sndinfo structure is defined as per RFC as below ...

  struct sctp_sndinfo {
    uint16_t snd_sid;
    uint16_t snd_flags;
    uint32_t snd_ppid;
    uint32_t snd_context;
    sctp_assoc_t snd_assoc_id;
  };

... and supplied under cmsg_level IPPROTO_SCTP, cmsg_type
SCTP_SNDINFO, while cmsg_data[] contains struct sctp_sndinfo.
An sctp_sndinfo item always corresponds to the data in msg_iov.

Joint work with Daniel Borkmann.

Signed-off-by: Geir Ola Vaagland <geirola@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Geir Ola Vaagland authored and David S. Miller committed Jul 16, 2014
1 parent 1a98c69 commit 63b9493
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Showing 3 changed files with 79 additions and 23 deletions.
3 changes: 2 additions & 1 deletion include/net/sctp/structs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1919,7 +1919,8 @@ struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc);
/* A convenience structure to parse out SCTP specific CMSGs. */
typedef struct sctp_cmsgs {
struct sctp_initmsg *init;
struct sctp_sndrcvinfo *info;
struct sctp_sndrcvinfo *srinfo;
struct sctp_sndinfo *sinfo;
} sctp_cmsgs_t;

/* Structure for tracking memory objects */
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22 changes: 20 additions & 2 deletions include/uapi/linux/sctp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,22 @@ struct sctp_sndrcvinfo {
sctp_assoc_t sinfo_assoc_id;
};

/* 5.3.4 SCTP Send Information Structure (SCTP_SNDINFO)
*
* This cmsghdr structure specifies SCTP options for sendmsg().
*
* cmsg_level cmsg_type cmsg_data[]
* ------------ ------------ -------------------
* IPPROTO_SCTP SCTP_SNDINFO struct sctp_sndinfo
*/
struct sctp_sndinfo {
__u16 snd_sid;
__u16 snd_flags;
__u32 snd_ppid;
__u32 snd_context;
sctp_assoc_t snd_assoc_id;
};

/*
* sinfo_flags: 16 bits (unsigned integer)
*
Expand All @@ -177,10 +193,12 @@ typedef union {

/* These are cmsg_types. */
typedef enum sctp_cmsg_type {
SCTP_INIT, /* 5.2.1 SCTP Initiation Structure */
SCTP_INIT, /* 5.2.1 SCTP Initiation Structure */
#define SCTP_INIT SCTP_INIT
SCTP_SNDRCV, /* 5.2.2 SCTP Header Information Structure */
SCTP_SNDRCV, /* 5.2.2 SCTP Header Information Structure */
#define SCTP_SNDRCV SCTP_SNDRCV
SCTP_SNDINFO, /* 5.3.4 SCTP Send Information Structure */
#define SCTP_SNDINFO SCTP_SNDINFO
} sctp_cmsg_t;

/*
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77 changes: 57 additions & 20 deletions net/sctp/socket.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1602,12 +1602,13 @@ static int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
struct sctp_initmsg *sinit;
sctp_assoc_t associd = 0;
sctp_cmsgs_t cmsgs = { NULL };
int err;
sctp_scope_t scope;
long timeo;
__u16 sinfo_flags = 0;
bool fill_sinfo_ttl = false;
struct sctp_datamsg *datamsg;
int msg_flags = msg->msg_flags;
__u16 sinfo_flags = 0;
long timeo;
int err;

err = 0;
sp = sctp_sk(sk);
Expand Down Expand Up @@ -1648,10 +1649,21 @@ static int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
msg_name = msg->msg_name;
}

sinfo = cmsgs.info;
sinit = cmsgs.init;
if (cmsgs.sinfo != NULL) {
memset(&default_sinfo, 0, sizeof(default_sinfo));
default_sinfo.sinfo_stream = cmsgs.sinfo->snd_sid;
default_sinfo.sinfo_flags = cmsgs.sinfo->snd_flags;
default_sinfo.sinfo_ppid = cmsgs.sinfo->snd_ppid;
default_sinfo.sinfo_context = cmsgs.sinfo->snd_context;
default_sinfo.sinfo_assoc_id = cmsgs.sinfo->snd_assoc_id;

/* Did the user specify SNDRCVINFO? */
sinfo = &default_sinfo;
fill_sinfo_ttl = true;
} else {
sinfo = cmsgs.srinfo;
}
/* Did the user specify SNDINFO/SNDRCVINFO? */
if (sinfo) {
sinfo_flags = sinfo->sinfo_flags;
associd = sinfo->sinfo_assoc_id;
Expand Down Expand Up @@ -1858,8 +1870,8 @@ static int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
pr_debug("%s: we have a valid association\n", __func__);

if (!sinfo) {
/* If the user didn't specify SNDRCVINFO, make up one with
* some defaults.
/* If the user didn't specify SNDINFO/SNDRCVINFO, make up
* one with some defaults.
*/
memset(&default_sinfo, 0, sizeof(default_sinfo));
default_sinfo.sinfo_stream = asoc->default_stream;
Expand All @@ -1868,7 +1880,13 @@ static int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
default_sinfo.sinfo_context = asoc->default_context;
default_sinfo.sinfo_timetolive = asoc->default_timetolive;
default_sinfo.sinfo_assoc_id = sctp_assoc2id(asoc);

sinfo = &default_sinfo;
} else if (fill_sinfo_ttl) {
/* In case SNDINFO was specified, we still need to fill
* it with a default ttl from the assoc here.
*/
sinfo->sinfo_timetolive = asoc->default_timetolive;
}

/* API 7.1.7, the sndbuf size per association bounds the
Expand Down Expand Up @@ -6390,8 +6408,7 @@ static int sctp_msghdr_parse(const struct msghdr *msg, sctp_cmsgs_t *cmsgs)
struct cmsghdr *cmsg;
struct msghdr *my_msg = (struct msghdr *)msg;

for (cmsg = CMSG_FIRSTHDR(msg);
cmsg != NULL;
for (cmsg = CMSG_FIRSTHDR(msg); cmsg != NULL;
cmsg = CMSG_NXTHDR(my_msg, cmsg)) {
if (!CMSG_OK(my_msg, cmsg))
return -EINVAL;
Expand All @@ -6404,7 +6421,7 @@ static int sctp_msghdr_parse(const struct msghdr *msg, sctp_cmsgs_t *cmsgs)
switch (cmsg->cmsg_type) {
case SCTP_INIT:
/* SCTP Socket API Extension
* 5.2.1 SCTP Initiation Structure (SCTP_INIT)
* 5.3.1 SCTP Initiation Structure (SCTP_INIT)
*
* This cmsghdr structure provides information for
* initializing new SCTP associations with sendmsg().
Expand All @@ -6416,15 +6433,15 @@ static int sctp_msghdr_parse(const struct msghdr *msg, sctp_cmsgs_t *cmsgs)
* ------------ ------------ ----------------------
* IPPROTO_SCTP SCTP_INIT struct sctp_initmsg
*/
if (cmsg->cmsg_len !=
CMSG_LEN(sizeof(struct sctp_initmsg)))
if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct sctp_initmsg)))
return -EINVAL;
cmsgs->init = (struct sctp_initmsg *)CMSG_DATA(cmsg);

cmsgs->init = CMSG_DATA(cmsg);
break;

case SCTP_SNDRCV:
/* SCTP Socket API Extension
* 5.2.2 SCTP Header Information Structure(SCTP_SNDRCV)
* 5.3.2 SCTP Header Information Structure(SCTP_SNDRCV)
*
* This cmsghdr structure specifies SCTP options for
* sendmsg() and describes SCTP header information
Expand All @@ -6434,24 +6451,44 @@ static int sctp_msghdr_parse(const struct msghdr *msg, sctp_cmsgs_t *cmsgs)
* ------------ ------------ ----------------------
* IPPROTO_SCTP SCTP_SNDRCV struct sctp_sndrcvinfo
*/
if (cmsg->cmsg_len !=
CMSG_LEN(sizeof(struct sctp_sndrcvinfo)))
if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct sctp_sndrcvinfo)))
return -EINVAL;

cmsgs->info =
(struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
cmsgs->srinfo = CMSG_DATA(cmsg);

/* Minimally, validate the sinfo_flags. */
if (cmsgs->info->sinfo_flags &
if (cmsgs->srinfo->sinfo_flags &
~(SCTP_UNORDERED | SCTP_ADDR_OVER |
SCTP_ABORT | SCTP_EOF))
return -EINVAL;
break;

case SCTP_SNDINFO:
/* SCTP Socket API Extension
* 5.3.4 SCTP Send Information Structure (SCTP_SNDINFO)
*
* This cmsghdr structure specifies SCTP options for
* sendmsg(). This structure and SCTP_RCVINFO replaces
* SCTP_SNDRCV which has been deprecated.
*
* cmsg_level cmsg_type cmsg_data[]
* ------------ ------------ ---------------------
* IPPROTO_SCTP SCTP_SNDINFO struct sctp_sndinfo
*/
if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct sctp_sndinfo)))
return -EINVAL;

cmsgs->sinfo = CMSG_DATA(cmsg);

if (cmsgs->sinfo->snd_flags &
~(SCTP_UNORDERED | SCTP_ADDR_OVER |
SCTP_ABORT | SCTP_EOF))
return -EINVAL;
break;
default:
return -EINVAL;
}
}

return 0;
}

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