fs/nfs/nfs4namespace.c

   1 /*
   2  * linux/fs/nfs/nfs4namespace.c
   3  *
   4  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
   5  * - Modified by David Howells <dhowells@redhat.com>
   6  *
   7  * NFSv4 namespace
   8  */
   9
  10 #include <linux/dcache.h>
  11 #include <linux/mount.h>
  12 #include <linux/namei.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/string.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/vfs.h>
  17 #include <linux/inet.h>
  18 #include "internal.h"
  19 #include "nfs4_fs.h"
  20 #include "dns_resolve.h"
  21
  22 #define NFSDBG_FACILITY         NFSDBG_VFS
  23
  24 /*
  25  * Convert the NFSv4 pathname components into a standard posix path.
  26  *
  27  * Note that the resulting string will be placed at the end of the buffer
  28  */
  29 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  30                                          char *buffer, ssize_t buflen)
  31 {
  32         char *end = buffer + buflen;
  33         int n;
  34
  35         *--end = '\0';
  36         buflen--;
  37
  38         n = pathname->ncomponents;
  39         while (--n >= 0) {
  40                 const struct nfs4_string *component = &pathname->components[n];
  41                 buflen -= component->len + 1;
  42                 if (buflen < 0)
  43                         goto Elong;
  44                 end -= component->len;
  45                 memcpy(end, component->data, component->len);
  46                 *--end = '/';
  47         }
  48         return end;
  49 Elong:
  50         return ERR_PTR(-ENAMETOOLONG);
  51 }
  52
  53 /*
  54  * Determine the mount path as a string
  55  */
  56 static char *nfs4_path(const struct vfsmount *mnt_parent,
  57                        const struct dentry *dentry,
  58                        char *buffer, ssize_t buflen)
  59 {
  60         const char *srvpath;
  61
  62         srvpath = strchr(mnt_parent->mnt_devname, ':');
  63         if (srvpath)
  64                 srvpath++;
  65         else
  66                 srvpath = mnt_parent->mnt_devname;
  67
  68         return nfs_path(srvpath, mnt_parent->mnt_root, dentry, buffer, buflen);
  69 }
  70
  71 /*
  72  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  73  * believe to be the server path to this dentry
  74  */
  75 static int nfs4_validate_fspath(const struct vfsmount *mnt_parent,
  76                                 const struct dentry *dentry,
  77                                 const struct nfs4_fs_locations *locations,
  78                                 char *page, char *page2)
  79 {
  80         const char *path, *fs_path;
  81
  82         path = nfs4_path(mnt_parent, dentry, page, PAGE_SIZE);
  83         if (IS_ERR(path))
  84                 return PTR_ERR(path);
  85
  86         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
  87         if (IS_ERR(fs_path))
  88                 return PTR_ERR(fs_path);
  89
  90         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
  91                 dprintk("%s: path %s does not begin with fsroot %s\n",
  92                         __func__, path, fs_path);
  93                 return -ENOENT;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static size_t nfs_parse_server_name(char *string, size_t len,
 100                 struct sockaddr *sa, size_t salen)
 101 {
 102         ssize_t ret;
 103
 104         ret = rpc_pton(string, len, sa, salen);
 105         if (ret == 0) {
 106                 ret = nfs_dns_resolve_name(string, len, sa, salen);
 107                 if (ret < 0)
 108                         ret = 0;
 109         }
 110         return ret;
 111 }
 112
 113 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 114                                      char *page, char *page2,
 115                                      const struct nfs4_fs_location *location)
 116 {
 117         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 118         char *mnt_path;
 119         unsigned int maxbuflen;
 120         unsigned int s;
 121
 122         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 123         if (IS_ERR(mnt_path))
 124                 return mnt;
 125         mountdata->mnt_path = mnt_path;
 126         maxbuflen = mnt_path - 1 - page2;
 127
 128         for (s = 0; s < location->nservers; s++) {
 129                 const struct nfs4_string *buf = &location->servers[s];
 130                 struct sockaddr_storage addr;
 131
 132                 if (buf->len <= 0 || buf->len >= maxbuflen)
 133                         continue;
 134
 135                 mountdata->addr = (struct sockaddr *)&addr;
 136
 137                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 138                         continue;
 139                 mountdata->addrlen = nfs_parse_server_name(buf->data,
 140                                 buf->len,
 141                                 mountdata->addr, mountdata->addrlen);
 142                 if (mountdata->addrlen == 0)
 143                         continue;
 144                 rpc_set_port(mountdata->addr, NFS_PORT);
 145
 146                 memcpy(page2, buf->data, buf->len);
 147                 page2[buf->len] = '\0';
 148                 mountdata->hostname = page2;
 149
 150                 snprintf(page, PAGE_SIZE, "%s:%s",
 151                                 mountdata->hostname,
 152                                 mountdata->mnt_path);
 153
 154                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 155                 if (!IS_ERR(mnt))
 156                         break;
 157         }
 158         return mnt;
 159 }
 160
 161 /**
 162  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 163  * @mnt_parent - mountpoint of parent directory
 164  * @dentry - parent directory
 165  * @locations - array of NFSv4 server location information
 166  *
 167  */
 168 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 169                                             const struct dentry *dentry,
 170                                             const struct nfs4_fs_locations *locations)
 171 {
 172         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 173         struct nfs_clone_mount mountdata = {
 174                 .sb = mnt_parent->mnt_sb,
 175                 .dentry = dentry,
 176                 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
 177         };
 178         char *page = NULL, *page2 = NULL;
 179         int loc, error;
 180
 181         if (locations == NULL || locations->nlocations <= 0)
 182                 goto out;
 183
 184         dprintk("%s: referral at %s/%s\n", __func__,
 185                 dentry->d_parent->d_name.name, dentry->d_name.name);
 186
 187         page = (char *) __get_free_page(GFP_USER);
 188         if (!page)
 189                 goto out;
 190
 191         page2 = (char *) __get_free_page(GFP_USER);
 192         if (!page2)
 193                 goto out;
 194
 195         /* Ensure fs path is a prefix of current dentry path */
 196         error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
 197         if (error < 0) {
 198                 mnt = ERR_PTR(error);
 199                 goto out;
 200         }
 201
 202         for (loc = 0; loc < locations->nlocations; loc++) {
 203                 const struct nfs4_fs_location *location = &locations->locations[loc];
 204
 205                 if (location == NULL || location->nservers <= 0 ||
 206                     location->rootpath.ncomponents == 0)
 207                         continue;
 208
 209                 mnt = try_location(&mountdata, page, page2, location);
 210                 if (!IS_ERR(mnt))
 211                         break;
 212         }
 213
 214 out:
 215         free_page((unsigned long) page);
 216         free_page((unsigned long) page2);
 217         dprintk("%s: done\n", __func__);
 218         return mnt;
 219 }
 220
 221 /*
 222  * nfs_do_refmount - handle crossing a referral on server
 223  * @dentry - dentry of referral
 224  * @nd - nameidata info
 225  *
 226  */
 227 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 228 {
 229         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 230         struct dentry *parent;
 231         struct nfs4_fs_locations *fs_locations = NULL;
 232         struct page *page;
 233         int err;
 234
 235         /* BUG_ON(IS_ROOT(dentry)); */
 236         dprintk("%s: enter\n", __func__);
 237
 238         page = alloc_page(GFP_KERNEL);
 239         if (page == NULL)
 240                 goto out;
 241
 242         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 243         if (fs_locations == NULL)
 244                 goto out_free;
 245
 246         /* Get locations */
 247         mnt = ERR_PTR(-ENOENT);
 248
 249         parent = dget_parent(dentry);
 250         dprintk("%s: getting locations for %s/%s\n",
 251                 __func__, parent->d_name.name, dentry->d_name.name);
 252
 253         err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);
 254         dput(parent);
 255         if (err != 0 ||
 256             fs_locations->nlocations <= 0 ||
 257             fs_locations->fs_path.ncomponents <= 0)
 258                 goto out_free;
 259
 260         mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
 261 out_free:
 262         __free_page(page);
 263         kfree(fs_locations);
 264 out:
 265         dprintk("%s: done\n", __func__);
 266         return mnt;
 267 }