On Fri, Nov 16, 2018 at 2:22 AM Marcelo Ricardo Leitner
[off-list ref] wrote:

On Thu, Nov 15, 2018 at 07:14:28PM +0800, Xin Long wrote:

quoted

As rfc7496#section4.5 says about SCTP_PR_SUPPORTED:

   This socket option allows the enabling or disabling of the
   negotiation of PR-SCTP support for future associations.  For existing
   associations, it allows one to query whether or not PR-SCTP support
   was negotiated on a particular association.

It means only sctp sock's prsctp_enable can be set.

Note that for the limitation of SCTP_{CURRENT|ALL}_ASSOC, we will
add it when introducing SCTP_{FUTURE|CURRENT|ALL}_ASSOC for linux
sctp in another patchset.

Fixes: 28aa4c26fce2 ("sctp: add SCTP_PR_SUPPORTED on sctp sockopt")
Reported-by: Ying Xu <redacted>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/sctp/socket.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 739f3e5..e9b8232 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c

@@ -3940,7 +3940,6 @@ static int sctp_setsockopt_pr_supported(struct sock *sk,
                                      unsigned int optlen)
 {
      struct sctp_assoc_value params;
-     struct sctp_association *asoc;
      int retval = -EINVAL;

      if (optlen != sizeof(params))

@@ -3951,16 +3950,10 @@ static int sctp_setsockopt_pr_supported(struct sock *sk,
              goto out;
      }

-     asoc = sctp_id2assoc(sk, params.assoc_id);
-     if (asoc) {
-             asoc->prsctp_enable = !!params.assoc_value;
-     } else if (!params.assoc_id) {
-             struct sctp_sock *sp = sctp_sk(sk);
-
-             sp->ep->prsctp_enable = !!params.assoc_value;
-     } else {
+     if (sctp_style(sk, UDP) && sctp_id2assoc(sk, params.assoc_id))

I got this semantic from BSD's SCTP_PR_SUPPORTED sockopt:
                        SCTP_FIND_STCB(inp, stcb, av->assoc_id);

                        if (stcb) {
                                SCTP_LTRACE_ERR_RET(...);
                                error = EINVAL;
                                SCTP_TCB_UNLOCK(stcb);
                        } else {
                                ...
                        }

This would allow using a non-existent assoc id on UDP-style sockets to
set it at the socket, which is not expected. It should be more like:

+       if (sctp_style(sk, UDP) && params.assoc_id)

This way is more strict, but it seems reasonable.

When a user sets params.assoc_id for UDP type socket, it should be
thought as he WANTs to apply this on assoc, which is not allowed here.