1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * NFS server support for local clients to bypass network stack
4 *
5 * Copyright (C) 2014 Weston Andros Adamson <dros@primarydata.com>
6 * Copyright (C) 2019 Trond Myklebust <trond.myklebust@hammerspace.com>
7 * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
8 * Copyright (C) 2024 NeilBrown <neilb@suse.de>
9 */
10
11 #include <linux/exportfs.h>
12 #include <linux/sunrpc/svcauth.h>
13 #include <linux/sunrpc/clnt.h>
14 #include <linux/nfs.h>
15 #include <linux/nfs_common.h>
16 #include <linux/nfslocalio.h>
17 #include <linux/nfs_fs.h>
18 #include <linux/nfs_xdr.h>
19 #include <linux/string.h>
20
21 #include "nfsd.h"
22 #include "vfs.h"
23 #include "netns.h"
24 #include "filecache.h"
25 #include "cache.h"
26
27 /**
28 * nfsd_open_local_fh - lookup a local filehandle @nfs_fh and map to nfsd_file
29 *
30 * @net: 'struct net' to get the proper nfsd_net required for LOCALIO access
31 * @dom: 'struct auth_domain' required for LOCALIO access
32 * @rpc_clnt: rpc_clnt that the client established
33 * @cred: cred that the client established
34 * @nfs_fh: filehandle to lookup
35 * @pnf: place to find the nfsd_file, or store it if it was non-NULL
36 * @fmode: fmode_t to use for open
37 *
38 * This function maps a local fh to a path on a local filesystem.
39 * This is useful when the nfs client has the local server mounted - it can
40 * avoid all the NFS overhead with reads, writes and commits.
41 *
42 * On successful return, returned nfsd_file will have its nf_net member
43 * set. Caller (NFS client) is responsible for calling nfsd_net_put and
44 * nfsd_file_put (via nfs_to_nfsd_file_put_local).
45 */
46 static struct nfsd_file *
nfsd_open_local_fh(struct net * net,struct auth_domain * dom,struct rpc_clnt * rpc_clnt,const struct cred * cred,const struct nfs_fh * nfs_fh,struct nfsd_file __rcu ** pnf,const fmode_t fmode)47 nfsd_open_local_fh(struct net *net, struct auth_domain *dom,
48 struct rpc_clnt *rpc_clnt, const struct cred *cred,
49 const struct nfs_fh *nfs_fh, struct nfsd_file __rcu **pnf,
50 const fmode_t fmode)
51 {
52 int mayflags = NFSD_MAY_LOCALIO;
53 struct svc_cred rq_cred;
54 struct svc_fh fh;
55 struct nfsd_file *localio;
56 __be32 beres;
57
58 if (nfs_fh->size > NFS4_FHSIZE)
59 return ERR_PTR(-EINVAL);
60
61 if (!nfsd_net_try_get(net))
62 return ERR_PTR(-ENXIO);
63
64 rcu_read_lock();
65 localio = nfsd_file_get(rcu_dereference(*pnf));
66 rcu_read_unlock();
67 if (localio)
68 return localio;
69
70 /* nfs_fh -> svc_fh */
71 fh_init(&fh, NFS4_FHSIZE);
72 fh.fh_handle.fh_size = nfs_fh->size;
73 memcpy(fh.fh_handle.fh_raw, nfs_fh->data, nfs_fh->size);
74
75 if (fmode & FMODE_READ)
76 mayflags |= NFSD_MAY_READ;
77 if (fmode & FMODE_WRITE)
78 mayflags |= NFSD_MAY_WRITE;
79
80 svcauth_map_clnt_to_svc_cred_local(rpc_clnt, cred, &rq_cred);
81
82 beres = nfsd_file_acquire_local(net, &rq_cred, dom,
83 &fh, mayflags, &localio);
84 if (beres)
85 localio = ERR_PTR(nfs_stat_to_errno(be32_to_cpu(beres)));
86
87 fh_put(&fh);
88 if (rq_cred.cr_group_info)
89 put_group_info(rq_cred.cr_group_info);
90
91 if (!IS_ERR(localio)) {
92 struct nfsd_file *new;
93 if (!nfsd_net_try_get(net)) {
94 nfsd_file_put(localio);
95 nfsd_net_put(net);
96 return ERR_PTR(-ENXIO);
97 }
98 nfsd_file_get(localio);
99 again:
100 new = unrcu_pointer(cmpxchg(pnf, NULL, RCU_INITIALIZER(localio)));
101 if (new) {
102 /* Some other thread installed an nfsd_file */
103 if (nfsd_file_get(new) == NULL)
104 goto again;
105 /*
106 * Drop the ref we were going to install and the
107 * one we were going to return.
108 */
109 nfsd_file_put(localio);
110 nfsd_file_put(localio);
111 localio = new;
112 }
113 } else
114 nfsd_net_put(net);
115
116 return localio;
117 }
118
119 static const struct nfsd_localio_operations nfsd_localio_ops = {
120 .nfsd_net_try_get = nfsd_net_try_get,
121 .nfsd_net_put = nfsd_net_put,
122 .nfsd_open_local_fh = nfsd_open_local_fh,
123 .nfsd_file_put_local = nfsd_file_put_local,
124 .nfsd_file_get_local = nfsd_file_get_local,
125 .nfsd_file_file = nfsd_file_file,
126 };
127
nfsd_localio_ops_init(void)128 void nfsd_localio_ops_init(void)
129 {
130 nfs_to = &nfsd_localio_ops;
131 }
132
133 /*
134 * UUID_IS_LOCAL XDR functions
135 */
136
localio_proc_null(struct svc_rqst * rqstp)137 static __be32 localio_proc_null(struct svc_rqst *rqstp)
138 {
139 return rpc_success;
140 }
141
142 struct localio_uuidarg {
143 uuid_t uuid;
144 };
145
localio_proc_uuid_is_local(struct svc_rqst * rqstp)146 static __be32 localio_proc_uuid_is_local(struct svc_rqst *rqstp)
147 {
148 struct localio_uuidarg *argp = rqstp->rq_argp;
149 struct net *net = SVC_NET(rqstp);
150 struct nfsd_net *nn = net_generic(net, nfsd_net_id);
151
152 nfs_uuid_is_local(&argp->uuid, &nn->local_clients,
153 &nn->local_clients_lock,
154 net, rqstp->rq_client, THIS_MODULE);
155
156 return rpc_success;
157 }
158
localio_decode_uuidarg(struct svc_rqst * rqstp,struct xdr_stream * xdr)159 static bool localio_decode_uuidarg(struct svc_rqst *rqstp,
160 struct xdr_stream *xdr)
161 {
162 struct localio_uuidarg *argp = rqstp->rq_argp;
163 u8 uuid[UUID_SIZE];
164
165 if (decode_opaque_fixed(xdr, uuid, UUID_SIZE))
166 return false;
167 import_uuid(&argp->uuid, uuid);
168
169 return true;
170 }
171
172 static const struct svc_procedure localio_procedures1[] = {
173 [LOCALIOPROC_NULL] = {
174 .pc_func = localio_proc_null,
175 .pc_decode = nfssvc_decode_voidarg,
176 .pc_encode = nfssvc_encode_voidres,
177 .pc_argsize = sizeof(struct nfsd_voidargs),
178 .pc_ressize = sizeof(struct nfsd_voidres),
179 .pc_cachetype = RC_NOCACHE,
180 .pc_xdrressize = 0,
181 .pc_name = "NULL",
182 },
183 [LOCALIOPROC_UUID_IS_LOCAL] = {
184 .pc_func = localio_proc_uuid_is_local,
185 .pc_decode = localio_decode_uuidarg,
186 .pc_encode = nfssvc_encode_voidres,
187 .pc_argsize = sizeof(struct localio_uuidarg),
188 .pc_argzero = sizeof(struct localio_uuidarg),
189 .pc_ressize = sizeof(struct nfsd_voidres),
190 .pc_cachetype = RC_NOCACHE,
191 .pc_name = "UUID_IS_LOCAL",
192 },
193 };
194
195 #define LOCALIO_NR_PROCEDURES ARRAY_SIZE(localio_procedures1)
196 static DEFINE_PER_CPU_ALIGNED(unsigned long,
197 localio_count[LOCALIO_NR_PROCEDURES]);
198 const struct svc_version localio_version1 = {
199 .vs_vers = 1,
200 .vs_nproc = LOCALIO_NR_PROCEDURES,
201 .vs_proc = localio_procedures1,
202 .vs_dispatch = nfsd_dispatch,
203 .vs_count = localio_count,
204 .vs_xdrsize = XDR_QUADLEN(UUID_SIZE),
205 .vs_hidden = true,
206 };
207