[PATCH net-next 3/5] sctp: add SCTP_EXPOSE_POTENTIALLY_FAILED_STATE sockopt

[Xin Long]

This is a sockopt defined in section 7.3 of rfc7829: "Exposing
the Potentially Failed Path State", by which users can change
pf_expose per sock and asoc.

Signed-off-by: Xin Long <lucien....@gmail.com>
---
 include/uapi/linux/sctp.h |  1 +
 net/sctp/socket.c         | 76 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
index b6649d6..a15cc28 100644
--- a/include/uapi/linux/sctp.h
+++ b/include/uapi/linux/sctp.h
@@ -137,6 +137,7 @@ typedef __s32 sctp_assoc_t;
 #define SCTP_ASCONF_SUPPORTED  128
 #define SCTP_AUTH_SUPPORTED    129
 #define SCTP_ECN_SUPPORTED     130
+#define SCTP_EXPOSE_POTENTIALLY_FAILED_STATE   131
 
 /* PR-SCTP policies */
 #define SCTP_PR_SCTP_NONE      0x0000
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 33b93bb..e3a8e25 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4588,6 +4588,37 @@ static int sctp_setsockopt_ecn_supported(struct sock *sk,
        return retval;
 }
 
+static int sctp_setsockopt_pf_expose(struct sock *sk,
+                                    char __user *optval,
+                                    unsigned int optlen)
+{
+       struct sctp_assoc_value params;
+       struct sctp_association *asoc;
+       int retval = -EINVAL;
+
+       if (optlen != sizeof(params))
+               goto out;
+
+       if (copy_from_user(&params, optval, optlen)) {
+               retval = -EFAULT;
+               goto out;
+       }
+
+       asoc = sctp_id2assoc(sk, params.assoc_id);
+       if (!asoc && params.assoc_id != SCTP_FUTURE_ASSOC &&
+           sctp_style(sk, UDP))
+               goto out;
+
+       if (asoc)
+               asoc->pf_expose = !!params.assoc_value;
+       else
+               sctp_sk(sk)->pf_expose = !!params.assoc_value;
+       retval = 0;
+
+out:
+       return retval;
+}
+
 /* API 6.2 setsockopt(), getsockopt()
  *
  * Applications use setsockopt() and getsockopt() to set or retrieve
@@ -4797,6 +4828,9 @@ static int sctp_setsockopt(struct sock *sk, int level, 
int optname,
        case SCTP_ECN_SUPPORTED:
                retval = sctp_setsockopt_ecn_supported(sk, optval, optlen);
                break;
+       case SCTP_EXPOSE_POTENTIALLY_FAILED_STATE:
+               retval = sctp_setsockopt_pf_expose(sk, optval, optlen);
+               break;
        default:
                retval = -ENOPROTOOPT;
                break;
@@ -7906,6 +7940,45 @@ static int sctp_getsockopt_ecn_supported(struct sock 
*sk, int len,
        return retval;
 }
 
+static int sctp_getsockopt_pf_expose(struct sock *sk, int len,
+                                    char __user *optval,
+                                    int __user *optlen)
+{
+       struct sctp_assoc_value params;
+       struct sctp_association *asoc;
+       int retval = -EFAULT;
+
+       if (len < sizeof(params)) {
+               retval = -EINVAL;
+               goto out;
+       }
+
+       len = sizeof(params);
+       if (copy_from_user(&params, optval, len))
+               goto out;
+
+       asoc = sctp_id2assoc(sk, params.assoc_id);
+       if (!asoc && params.assoc_id != SCTP_FUTURE_ASSOC &&
+           sctp_style(sk, UDP)) {
+               retval = -EINVAL;
+               goto out;
+       }
+
+       params.assoc_value = asoc ? asoc->pf_expose
+                                 : sctp_sk(sk)->pf_expose;
+
+       if (put_user(len, optlen))
+               goto out;
+
+       if (copy_to_user(optval, &params, len))
+               goto out;
+
+       retval = 0;
+
+out:
+       return retval;
+}
+
 static int sctp_getsockopt(struct sock *sk, int level, int optname,
                           char __user *optval, int __user *optlen)
 {
@@ -8118,6 +8191,9 @@ static int sctp_getsockopt(struct sock *sk, int level, 
int optname,
        case SCTP_ECN_SUPPORTED:
                retval = sctp_getsockopt_ecn_supported(sk, len, optval, optlen);
                break;
+       case SCTP_EXPOSE_POTENTIALLY_FAILED_STATE:
+               retval = sctp_getsockopt_pf_expose(sk, len, optval, optlen);
+               break;
        default:
                retval = -ENOPROTOOPT;
                break;
-- 
2.1.0