nfsd4: check backchannel attributes on create_session

Make sure the client gives us an adequate backchannel.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

3 files changed, 49 insertions, 24 deletions

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index be3ff0f3ff68..7f05cd140de3 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -37,6 +37,7 @@
 #include "nfsd.h"
 #include "state.h"
 #include "netns.h"
+#include "xdr4cb.h"
 
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
@@ -53,30 +54,6 @@ enum {
         NFSPROC4_CLNT_CB_SEQUENCE,
 };
 
-#define NFS4_MAXTAGLEN          20
-
-#define NFS4_enc_cb_null_sz             0
-#define NFS4_dec_cb_null_sz             0
-#define cb_compound_enc_hdr_sz          4
-#define cb_compound_dec_hdr_sz          (3 + (NFS4_MAXTAGLEN >> 2))
-#define sessionid_sz                    (NFS4_MAX_SESSIONID_LEN >> 2)
-#define cb_sequence_enc_sz              (sessionid_sz + 4 +             \
-                                        1 /* no referring calls list yet */)
-#define cb_sequence_dec_sz              (op_dec_sz + sessionid_sz + 4)
-
-#define op_enc_sz                       1
-#define op_dec_sz                       2
-#define enc_nfs4_fh_sz                  (1 + (NFS4_FHSIZE >> 2))
-#define enc_stateid_sz                  (NFS4_STATEID_SIZE >> 2)
-#define NFS4_enc_cb_recall_sz           (cb_compound_enc_hdr_sz +       \
-                                        cb_sequence_enc_sz +            \
-                                        1 + enc_stateid_sz +            \
-                                        enc_nfs4_fh_sz)
-
-#define NFS4_dec_cb_recall_sz           (cb_compound_dec_hdr_sz  +      \
-                                        cb_sequence_dec_sz +            \
-                                        op_dec_sz)
-
 struct nfs4_cb_compound_hdr {
         /* args */
         u32             ident;  /* minorversion 0 only */
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 036d5f16fd7f..67017fcebb21 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -42,6 +42,7 @@
 #include <linux/sunrpc/svcauth_gss.h>
 #include <linux/sunrpc/addr.h>
 #include "xdr4.h"
+#include "xdr4cb.h"
 #include "vfs.h"
 #include "current_stateid.h"
 
@@ -1794,6 +1795,27 @@ static __be32 check_forechannel_attrs(struct nfsd4_channel_attrs *ca, struct nfs
         return nfs_ok;
 }
 
+static __be32 check_backchannel_attrs(struct nfsd4_channel_attrs *ca)
+{
+        ca->headerpadsz = 0;
+
+        /*
+         * These RPC_MAX_HEADER macros are overkill, especially since we
+         * don't even do gss on the backchannel yet.  But this is still
+         * less than 1k.  Tighten up this estimate in the unlikely event
+         * it turns out to be a problem for some client:
+         */
+        if (ca->maxreq_sz < NFS4_enc_cb_recall_sz + RPC_MAX_HEADER_WITH_AUTH)
+                return nfserr_toosmall;
+        if (ca->maxresp_sz < NFS4_dec_cb_recall_sz + RPC_MAX_REPHEADER_WITH_AUTH)
+                return nfserr_toosmall;
+        ca->maxresp_cached = 0;
+        if (ca->maxops < 2)
+                return nfserr_toosmall;
+
+        return nfs_ok;
+}
+
 __be32
 nfsd4_create_session(struct svc_rqst *rqstp,
                      struct nfsd4_compound_state *cstate,
@@ -1812,6 +1834,9 @@ nfsd4_create_session(struct svc_rqst *rqstp,
         status = check_forechannel_attrs(&cr_ses->fore_channel, nn);
         if (status)
                 return status;
+        status = check_backchannel_attrs(&cr_ses->back_channel);
+        if (status)
+                return status;
         status = nfserr_jukebox;
         new = alloc_session(&cr_ses->fore_channel);
         if (!new)
diff --git a/fs/nfsd/xdr4cb.h b/fs/nfsd/xdr4cb.h
new file mode 100644
index 000000000000..c5c55dfb91a9
--- /dev/null
+++ b/fs/nfsd/xdr4cb.h
@@ -0,0 +1,23 @@
+#define NFS4_MAXTAGLEN          20
+
+#define NFS4_enc_cb_null_sz             0
+#define NFS4_dec_cb_null_sz             0
+#define cb_compound_enc_hdr_sz          4
+#define cb_compound_dec_hdr_sz          (3 + (NFS4_MAXTAGLEN >> 2))
+#define sessionid_sz                    (NFS4_MAX_SESSIONID_LEN >> 2)
+#define cb_sequence_enc_sz              (sessionid_sz + 4 +             \
+                                        1 /* no referring calls list yet */)
+#define cb_sequence_dec_sz              (op_dec_sz + sessionid_sz + 4)
+
+#define op_enc_sz                       1
+#define op_dec_sz                       2
+#define enc_nfs4_fh_sz                  (1 + (NFS4_FHSIZE >> 2))
+#define enc_stateid_sz                  (NFS4_STATEID_SIZE >> 2)
+#define NFS4_enc_cb_recall_sz           (cb_compound_enc_hdr_sz +       \
+                                        cb_sequence_enc_sz +            \
+                                        1 + enc_stateid_sz +            \
+                                        enc_nfs4_fh_sz)
+
+#define NFS4_dec_cb_recall_sz           (cb_compound_dec_hdr_sz  +      \
+                                        cb_sequence_dec_sz +            \
+                                        op_dec_sz)