~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/nfs/namespace.c

Version: ~ [ linux-5.16-rc3 ] ~ [ linux-5.15.5 ] ~ [ linux-5.14.21 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.82 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.162 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.218 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.256 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.291 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.293 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * linux/fs/nfs/namespace.c
  4  *
  5  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
  6  * - Modified by David Howells <dhowells@redhat.com>
  7  *
  8  * NFS namespace
  9  */
 10 
 11 #include <linux/module.h>
 12 #include <linux/dcache.h>
 13 #include <linux/gfp.h>
 14 #include <linux/mount.h>
 15 #include <linux/namei.h>
 16 #include <linux/nfs_fs.h>
 17 #include <linux/string.h>
 18 #include <linux/sunrpc/clnt.h>
 19 #include <linux/vfs.h>
 20 #include <linux/sunrpc/gss_api.h>
 21 #include "internal.h"
 22 #include "nfs.h"
 23 
 24 #define NFSDBG_FACILITY         NFSDBG_VFS
 25 
 26 static void nfs_expire_automounts(struct work_struct *work);
 27 
 28 static LIST_HEAD(nfs_automount_list);
 29 static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
 30 int nfs_mountpoint_expiry_timeout = 500 * HZ;
 31 
 32 /*
 33  * nfs_path - reconstruct the path given an arbitrary dentry
 34  * @base - used to return pointer to the end of devname part of path
 35  * @dentry_in - pointer to dentry
 36  * @buffer - result buffer
 37  * @buflen_in - length of buffer
 38  * @flags - options (see below)
 39  *
 40  * Helper function for constructing the server pathname
 41  * by arbitrary hashed dentry.
 42  *
 43  * This is mainly for use in figuring out the path on the
 44  * server side when automounting on top of an existing partition
 45  * and in generating /proc/mounts and friends.
 46  *
 47  * Supported flags:
 48  * NFS_PATH_CANONICAL: ensure there is exactly one slash after
 49  *                     the original device (export) name
 50  *                     (if unset, the original name is returned verbatim)
 51  */
 52 char *nfs_path(char **p, struct dentry *dentry_in, char *buffer,
 53                ssize_t buflen_in, unsigned flags)
 54 {
 55         char *end;
 56         int namelen;
 57         unsigned seq;
 58         const char *base;
 59         struct dentry *dentry;
 60         ssize_t buflen;
 61 
 62 rename_retry:
 63         buflen = buflen_in;
 64         dentry = dentry_in;
 65         end = buffer+buflen;
 66         *--end = '\0';
 67         buflen--;
 68 
 69         seq = read_seqbegin(&rename_lock);
 70         rcu_read_lock();
 71         while (1) {
 72                 spin_lock(&dentry->d_lock);
 73                 if (IS_ROOT(dentry))
 74                         break;
 75                 namelen = dentry->d_name.len;
 76                 buflen -= namelen + 1;
 77                 if (buflen < 0)
 78                         goto Elong_unlock;
 79                 end -= namelen;
 80                 memcpy(end, dentry->d_name.name, namelen);
 81                 *--end = '/';
 82                 spin_unlock(&dentry->d_lock);
 83                 dentry = dentry->d_parent;
 84         }
 85         if (read_seqretry(&rename_lock, seq)) {
 86                 spin_unlock(&dentry->d_lock);
 87                 rcu_read_unlock();
 88                 goto rename_retry;
 89         }
 90         if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
 91                 if (--buflen < 0) {
 92                         spin_unlock(&dentry->d_lock);
 93                         rcu_read_unlock();
 94                         goto Elong;
 95                 }
 96                 *--end = '/';
 97         }
 98         *p = end;
 99         base = dentry->d_fsdata;
100         if (!base) {
101                 spin_unlock(&dentry->d_lock);
102                 rcu_read_unlock();
103                 WARN_ON(1);
104                 return end;
105         }
106         namelen = strlen(base);
107         if (*end == '/') {
108                 /* Strip off excess slashes in base string */
109                 while (namelen > 0 && base[namelen - 1] == '/')
110                         namelen--;
111         }
112         buflen -= namelen;
113         if (buflen < 0) {
114                 spin_unlock(&dentry->d_lock);
115                 rcu_read_unlock();
116                 goto Elong;
117         }
118         end -= namelen;
119         memcpy(end, base, namelen);
120         spin_unlock(&dentry->d_lock);
121         rcu_read_unlock();
122         return end;
123 Elong_unlock:
124         spin_unlock(&dentry->d_lock);
125         rcu_read_unlock();
126         if (read_seqretry(&rename_lock, seq))
127                 goto rename_retry;
128 Elong:
129         return ERR_PTR(-ENAMETOOLONG);
130 }
131 EXPORT_SYMBOL_GPL(nfs_path);
132 
133 /*
134  * nfs_d_automount - Handle crossing a mountpoint on the server
135  * @path - The mountpoint
136  *
137  * When we encounter a mountpoint on the server, we want to set up
138  * a mountpoint on the client too, to prevent inode numbers from
139  * colliding, and to allow "df" to work properly.
140  * On NFSv4, we also want to allow for the fact that different
141  * filesystems may be migrated to different servers in a failover
142  * situation, and that different filesystems may want to use
143  * different security flavours.
144  */
145 struct vfsmount *nfs_d_automount(struct path *path)
146 {
147         struct nfs_fs_context *ctx;
148         struct fs_context *fc;
149         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
150         struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
151         struct nfs_client *client = server->nfs_client;
152         int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
153         int ret;
154 
155         if (IS_ROOT(path->dentry))
156                 return ERR_PTR(-ESTALE);
157 
158         /* Open a new filesystem context, transferring parameters from the
159          * parent superblock, including the network namespace.
160          */
161         fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, path->dentry);
162         if (IS_ERR(fc))
163                 return ERR_CAST(fc);
164 
165         ctx = nfs_fc2context(fc);
166         ctx->clone_data.dentry  = path->dentry;
167         ctx->clone_data.sb      = path->dentry->d_sb;
168         ctx->clone_data.fattr   = nfs_alloc_fattr();
169         if (!ctx->clone_data.fattr)
170                 goto out_fc;
171 
172         if (fc->net_ns != client->cl_net) {
173                 put_net(fc->net_ns);
174                 fc->net_ns = get_net(client->cl_net);
175         }
176 
177         /* for submounts we want the same server; referrals will reassign */
178         memcpy(&ctx->nfs_server.address, &client->cl_addr, client->cl_addrlen);
179         ctx->nfs_server.addrlen = client->cl_addrlen;
180         ctx->nfs_server.port    = server->port;
181 
182         ctx->version            = client->rpc_ops->version;
183         ctx->minorversion       = client->cl_minorversion;
184         ctx->nfs_mod            = client->cl_nfs_mod;
185         __module_get(ctx->nfs_mod->owner);
186 
187         ret = client->rpc_ops->submount(fc, server);
188         if (ret < 0) {
189                 mnt = ERR_PTR(ret);
190                 goto out_fc;
191         }
192 
193         up_write(&fc->root->d_sb->s_umount);
194         mnt = vfs_create_mount(fc);
195         if (IS_ERR(mnt))
196                 goto out_fc;
197 
198         mntget(mnt); /* prevent immediate expiration */
199         if (timeout <= 0)
200                 goto out_fc;
201 
202         mnt_set_expiry(mnt, &nfs_automount_list);
203         schedule_delayed_work(&nfs_automount_task, timeout);
204 
205 out_fc:
206         put_fs_context(fc);
207         return mnt;
208 }
209 
210 static int
211 nfs_namespace_getattr(const struct path *path, struct kstat *stat,
212                         u32 request_mask, unsigned int query_flags)
213 {
214         if (NFS_FH(d_inode(path->dentry))->size != 0)
215                 return nfs_getattr(path, stat, request_mask, query_flags);
216         generic_fillattr(d_inode(path->dentry), stat);
217         return 0;
218 }
219 
220 static int
221 nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
222 {
223         if (NFS_FH(d_inode(dentry))->size != 0)
224                 return nfs_setattr(dentry, attr);
225         return -EACCES;
226 }
227 
228 const struct inode_operations nfs_mountpoint_inode_operations = {
229         .getattr        = nfs_getattr,
230         .setattr        = nfs_setattr,
231 };
232 
233 const struct inode_operations nfs_referral_inode_operations = {
234         .getattr        = nfs_namespace_getattr,
235         .setattr        = nfs_namespace_setattr,
236 };
237 
238 static void nfs_expire_automounts(struct work_struct *work)
239 {
240         struct list_head *list = &nfs_automount_list;
241         int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
242 
243         mark_mounts_for_expiry(list);
244         if (!list_empty(list) && timeout > 0)
245                 schedule_delayed_work(&nfs_automount_task, timeout);
246 }
247 
248 void nfs_release_automount_timer(void)
249 {
250         if (list_empty(&nfs_automount_list))
251                 cancel_delayed_work(&nfs_automount_task);
252 }
253 
254 /**
255  * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
256  * @fc: pointer to struct nfs_fs_context
257  *
258  */
259 int nfs_do_submount(struct fs_context *fc)
260 {
261         struct nfs_fs_context *ctx = nfs_fc2context(fc);
262         struct dentry *dentry = ctx->clone_data.dentry;
263         struct nfs_server *server;
264         char *buffer, *p;
265         int ret;
266 
267         /* create a new volume representation */
268         server = ctx->nfs_mod->rpc_ops->clone_server(NFS_SB(ctx->clone_data.sb),
269                                                      ctx->mntfh,
270                                                      ctx->clone_data.fattr,
271                                                      ctx->selected_flavor);
272 
273         if (IS_ERR(server))
274                 return PTR_ERR(server);
275 
276         ctx->server = server;
277 
278         buffer = kmalloc(4096, GFP_USER);
279         if (!buffer)
280                 return -ENOMEM;
281 
282         ctx->internal           = true;
283         ctx->clone_data.inherited_bsize = ctx->clone_data.sb->s_blocksize_bits;
284 
285         p = nfs_devname(dentry, buffer, 4096);
286         if (IS_ERR(p)) {
287                 nfs_errorf(fc, "NFS: Couldn't determine submount pathname");
288                 ret = PTR_ERR(p);
289         } else {
290                 ret = vfs_parse_fs_string(fc, "source", p, buffer + 4096 - p);
291                 if (!ret)
292                         ret = vfs_get_tree(fc);
293         }
294         kfree(buffer);
295         return ret;
296 }
297 EXPORT_SYMBOL_GPL(nfs_do_submount);
298 
299 int nfs_submount(struct fs_context *fc, struct nfs_server *server)
300 {
301         struct nfs_fs_context *ctx = nfs_fc2context(fc);
302         struct dentry *dentry = ctx->clone_data.dentry;
303         struct dentry *parent = dget_parent(dentry);
304         int err;
305 
306         /* Look it up again to get its attributes */
307         err = server->nfs_client->rpc_ops->lookup(d_inode(parent), dentry,
308                                                   ctx->mntfh, ctx->clone_data.fattr,
309                                                   NULL);
310         dput(parent);
311         if (err != 0)
312                 return err;
313 
314         ctx->selected_flavor = server->client->cl_auth->au_flavor;
315         return nfs_do_submount(fc);
316 }
317 EXPORT_SYMBOL_GPL(nfs_submount);
318 
319 static int param_set_nfs_timeout(const char *val, const struct kernel_param *kp)
320 {
321         long num;
322         int ret;
323 
324         if (!val)
325                 return -EINVAL;
326         ret = kstrtol(val, 0, &num);
327         if (ret)
328                 return -EINVAL;
329         if (num > 0) {
330                 if (num >= INT_MAX / HZ)
331                         num = INT_MAX;
332                 else
333                         num *= HZ;
334                 *((int *)kp->arg) = num;
335                 if (!list_empty(&nfs_automount_list))
336                         mod_delayed_work(system_wq, &nfs_automount_task, num);
337         } else {
338                 *((int *)kp->arg) = -1*HZ;
339                 cancel_delayed_work(&nfs_automount_task);
340         }
341         return 0;
342 }
343 
344 static int param_get_nfs_timeout(char *buffer, const struct kernel_param *kp)
345 {
346         long num = *((int *)kp->arg);
347 
348         if (num > 0) {
349                 if (num >= INT_MAX - (HZ - 1))
350                         num = INT_MAX / HZ;
351                 else
352                         num = (num + (HZ - 1)) / HZ;
353         } else
354                 num = -1;
355         return scnprintf(buffer, PAGE_SIZE, "%li\n", num);
356 }
357 
358 static const struct kernel_param_ops param_ops_nfs_timeout = {
359         .set = param_set_nfs_timeout,
360         .get = param_get_nfs_timeout,
361 };
362 #define param_check_nfs_timeout(name, p) __param_check(name, p, int);
363 
364 module_param(nfs_mountpoint_expiry_timeout, nfs_timeout, 0644);
365 MODULE_PARM_DESC(nfs_mountpoint_expiry_timeout,
366                 "Set the NFS automounted mountpoint timeout value (seconds)."
367                 "Values <= 0 turn expiration off.");
368 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp