On 08/28/2014 09:34 AM, Daniel Borkmann wrote:
On 08/28/2014 08:33 AM, 苏庆 wrote:
Hi all,
I found that In 3.x kernel, the sctp states are defined differently
between kernel and uapi header. This makes our application fails to
work.
Is that a mismatch or am I missing something?
You are correct, and that's not good ... can you try out the below
kernel patch?
Note, the problem is that we cannot just redefine the sctp_state_t
enum back to as it was as it's accessing a function pointer lookup
table, so I think it's better to just add this offset for user space
now. It's read-only anyway.
From 90653829a4d406898f6906849f3eca481ec01894 Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <dborkman@xxxxxxxxxx>
Date: Thu, 28 Aug 2014 09:26:36 +0200
Subject: [PATCH] net: sctp: fix ABI through sctp_assoc_to_state helper
Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
---
include/net/sctp/sctp.h | 13 +++++++++++++
net/sctp/socket.c | 2 +-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index f6e7397..f50dccf 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -320,6 +320,19 @@ static inline sctp_assoc_t sctp_assoc2id(const struct sctp_association *asoc)
return asoc ? asoc->assoc_id : 0;
}
+static inline enum sctp_sstat_state
+sctp_assoc_to_state(const struct sctp_association *asoc)
+{
+ /* SCTP's uapi always had SCTP_EMPTY(=0) as a dummy state, but we
+ * got rid of it in kernel space. Therefore SCTP_CLOSED et al
+ * start at =1 in user space, but actually as =0 in kernel space.
+ * Now that we may not break user space and SCTP_EMPTY is exposed
+ * there, hence we need to fix it up with an ugly offset to not
+ * break applications. :(
+ */
+ return asoc->state + 1;
+}
+
/* Look up the association by its id. */
struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id);
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index eb71d49..634a2ab 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4243,7 +4243,7 @@ static int sctp_getsockopt_sctp_status(struct sock *sk, int len,
transport = asoc->peer.primary_path;
status.sstat_assoc_id = sctp_assoc2id(asoc);
- status.sstat_state = asoc->state;
+ status.sstat_state = sctp_assoc_to_state(asoc);
status.sstat_rwnd = asoc->peer.rwnd;
status.sstat_unackdata = asoc->unack_data;
--
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