net: sctp: implement rfc6458, 5.3.4. SCTP_SNDINFO cmsg support

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>

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index f38588bf3462d9e2374258bb6c383e38413507ed..7af9a0f5d8ce9ccf381181e7f802fe8dfa9c72ac 100644 (file)
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -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 */

diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
index 266022a2be4acae990ed56c3efe783766d667d6e..a387761f7e02fba9c2157880b070416ef8a08e3c 100644 (file)
--- a/include/uapi/linux/sctp.h
+++ b/include/uapi/linux/sctp.h
@@ -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)
  *
@@ -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;
 
 /*

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 429899689408caec64cf5c36b4eb0b00369f8e48..d61729e99856dfb6a030761d0d974739a121887f 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -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);
@@ -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;
@@ -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;
@@ -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
@@ -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;
@@ -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().
@@ -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
@@ -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;
 }