2023-05-02 19:03:40

by Chuck Lever

Subject: [PATCH] SUNRPC: Fix encoding of rejected RPCs

From: Chuck Lever <[email protected]>

Jiri Slaby says:
> I bisected to this ... as it breaks nfs3-only servers in 6.3.
> I.e. /etc/nfs.conf containing:
> [nfsd]
> vers4=no
>
> The client sees:
> mount("10.0.2.15:/tmp", "/mnt", "nfs", 0, "vers=4.2,addr=10.0.2.15,clientad"...) = -1 EIO (Input/output error)
> write(2, "mount.nfs: mount system call fai"..., 45
> mount.nfs: mount system call failed for /mnt
>
> And the kernel says:
> nfs4_discover_server_trunking unhandled error -5. Exiting with error EIO

Reported-by: Jiri Slaby <[email protected]>
Link: https://bugzilla.suse.com/show_bug.cgi?id=1210995
Fixes: 4bcf0343e8a6 ("SUNRPC: Set rq_accept_statp inside ->accept methods")
Signed-off-by: Chuck Lever <[email protected]>
---
net/sunrpc/svc.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index fea7ce8fba14..9874a6de1de3 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1382,7 +1382,7 @@ svc_process_common(struct svc_rqst *rqstp)
/* Only RPCv2 supported */
xdr_stream_encode_u32(xdr, RPC_VERSION);
xdr_stream_encode_u32(xdr, RPC_VERSION);
- goto sendit;
+ return 1; /* don't wrap */

err_bad_auth:
dprintk("svc: authentication failed (%d)\n",
@@ -1398,7 +1398,7 @@ svc_process_common(struct svc_rqst *rqstp)
err_bad_prog:
dprintk("svc: unknown program %d\n", rqstp->rq_prog);
serv->sv_stats->rpcbadfmt++;
- xdr_stream_encode_u32(xdr, RPC_PROG_UNAVAIL);
+ *rqstp->rq_accept_statp = rpc_prog_unavail;
goto sendit;

err_bad_vers:
@@ -1406,7 +1406,12 @@ svc_process_common(struct svc_rqst *rqstp)
rqstp->rq_vers, rqstp->rq_prog, progp->pg_name);

serv->sv_stats->rpcbadfmt++;
- xdr_stream_encode_u32(xdr, RPC_PROG_MISMATCH);
+ *rqstp->rq_accept_statp = rpc_prog_mismatch;
+
+ /*
+ * svc_authenticate() has already added the verifier and
+ * advanced the stream just past rq_accept_statp.
+ */
xdr_stream_encode_u32(xdr, process.mismatch.lovers);
xdr_stream_encode_u32(xdr, process.mismatch.hivers);
goto sendit;
@@ -1415,19 +1420,19 @@ svc_process_common(struct svc_rqst *rqstp)
svc_printk(rqstp, "unknown procedure (%d)\n", rqstp->rq_proc);

serv->sv_stats->rpcbadfmt++;
- xdr_stream_encode_u32(xdr, RPC_PROC_UNAVAIL);
+ *rqstp->rq_accept_statp = rpc_proc_unavail;
goto sendit;

err_garbage_args:
svc_printk(rqstp, "failed to decode RPC header\n");

serv->sv_stats->rpcbadfmt++;
- xdr_stream_encode_u32(xdr, RPC_GARBAGE_ARGS);
+ *rqstp->rq_accept_statp = rpc_garbage_args;
goto sendit;

err_system_err:
serv->sv_stats->rpcbadfmt++;
- xdr_stream_encode_u32(xdr, RPC_SYSTEM_ERR);
+ *rqstp->rq_accept_statp = rpc_system_err;
goto sendit;
}

2023-05-03 05:09:06

by Jiri Slaby (SUSE)

Subject: Re: [PATCH] SUNRPC: Fix encoding of rejected RPCs

On 02. 05. 23, 20:59, Chuck Lever wrote:
> From: Chuck Lever <[email protected]>
>
> Jiri Slaby says:
>> I bisected to this ... as it breaks nfs3-only servers in 6.3.
>> I.e. /etc/nfs.conf containing:
>> [nfsd]
>> vers4=no
>>
>> The client sees:
>> mount("10.0.2.15:/tmp", "/mnt", "nfs", 0, "vers=4.2,addr=10.0.2.15,clientad"...) = -1 EIO (Input/output error)
>> write(2, "mount.nfs: mount system call fai"..., 45
>> mount.nfs: mount system call failed for /mnt
>>
>> And the kernel says:
>> nfs4_discover_server_trunking unhandled error -5. Exiting with error EIO
>
> Reported-by: Jiri Slaby <[email protected]>

Tested-by: Jiri Slaby <[email protected]>

--
js
suse labs