NFSD: Fix handling of oversized NFSv4 COMPOUND requests

[ Upstream commit 7518a3dc5ea249d4112156ce71b8b184eb786151 ]

If an NFS server returns NFS4ERR_RESOURCE on the first operation in
an NFSv4 COMPOUND, there's no way for a client to know where the
problem is and then simplify the compound to make forward progress.

So instead, make NFSD process as many operations in an oversized
COMPOUND as it can and then return NFS4ERR_RESOURCE on the first
operation it did not process.

pynfs NFSv4.0 COMP6 exercises this case, but checks only for the
COMPOUND status code, not whether the server has processed any
of the operations.

pynfs NFSv4.1 SEQ6 and SEQ7 exercise the NFSv4.1 case, which detects
too many operations per COMPOUND by checking against the limits
negotiated when the session was created.

Suggested-by: Bruce Fields <bfields@fieldses.org>
Fixes: 0078117c6d91 ("nfsd: return RESOURCE not GARBAGE_ARGS on too many ops")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index f7584787dab2a7d71261e6e7c7154019c3f00c44..09dd70f791581ecbdc4afeae3befe705de0498af 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -2493,9 +2493,6 @@ nfsd4_proc_compound(struct svc_rqst *rqstp)
        status = nfserr_minor_vers_mismatch;
        if (nfsd_minorversion(nn, args->minorversion, NFSD_TEST) <= 0)
                goto out;
-       status = nfserr_resource;
-       if (args->opcnt > NFSD_MAX_OPS_PER_COMPOUND)
-               goto out;
 
        status = nfs41_check_op_ordering(args);
        if (status) {
@@ -2508,10 +2505,20 @@ nfsd4_proc_compound(struct svc_rqst *rqstp)
 
        rqstp->rq_lease_breaker = (void **)&cstate->clp;
 
-       trace_nfsd_compound(rqstp, args->opcnt);
+       trace_nfsd_compound(rqstp, args->client_opcnt);
        while (!status && resp->opcnt < args->opcnt) {
                op = &args->ops[resp->opcnt++];
 
+               if (unlikely(resp->opcnt == NFSD_MAX_OPS_PER_COMPOUND)) {
+                       /* If there are still more operations to process,
+                        * stop here and report NFS4ERR_RESOURCE. */
+                       if (cstate->minorversion == 0 &&
+                           args->client_opcnt > resp->opcnt) {
+                               op->status = nfserr_resource;
+                               goto encode_op;
+                       }
+               }
+
                /*
                 * The XDR decode routines may have pre-set op->status;
                 * for example, if there is a miscellaneous XDR error
@@ -2587,8 +2594,8 @@ encode_op:
                        status = op->status;
                }
 
-               trace_nfsd_compound_status(args->opcnt, resp->opcnt, status,
-                                          nfsd4_op_name(op->opnum));
+               trace_nfsd_compound_status(args->client_opcnt, resp->opcnt,
+                                          status, nfsd4_op_name(op->opnum));
 
                nfsd4_cstate_clear_replay(cstate);
                nfsd4_increment_op_stats(op->opnum);

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index f6d385e0efece3530efc1415099272469aec194d..bda8478eb1ae075c48e123099eaa5a8df9c65a86 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2349,16 +2349,11 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
 
        if (xdr_stream_decode_u32(argp->xdr, &argp->minorversion) < 0)
                return 0;
-       if (xdr_stream_decode_u32(argp->xdr, &argp->opcnt) < 0)
+       if (xdr_stream_decode_u32(argp->xdr, &argp->client_opcnt) < 0)
                return 0;
 
-       /*
-        * NFS4ERR_RESOURCE is a more helpful error than GARBAGE_ARGS
-        * here, so we return success at the xdr level so that
-        * nfsd4_proc can handle this is an NFS-level error.
-        */
-       if (argp->opcnt > NFSD_MAX_OPS_PER_COMPOUND)
-               return 1;
+       argp->opcnt = min_t(u32, argp->client_opcnt,
+                           NFSD_MAX_OPS_PER_COMPOUND);
 
        if (argp->opcnt > ARRAY_SIZE(argp->iops)) {
                argp->ops = kzalloc(argp->opcnt * sizeof(*argp->ops), GFP_KERNEL);

diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 3e4052e3bd50eebf43327842fd9822deb36285e1..45257666a6888e990f768acf4f1469b316ca4f40 100644 (file)
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -688,9 +688,10 @@ struct nfsd4_compoundargs {
        struct svcxdr_tmpbuf            *to_free;
        struct svc_rqst                 *rqstp;
 
-       u32                             taglen;
        char *                          tag;
+       u32                             taglen;
        u32                             minorversion;
+       u32                             client_opcnt;
        u32                             opcnt;
        struct nfsd4_op                 *ops;
        struct nfsd4_op                 iops[8];