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
  21 #define NFSDBG_FACILITY         NFSDBG_VFS
  22
  23 /*
  24  * Check if fs_root is valid
  25  */
  26 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  27                                          char *buffer, ssize_t buflen)
  28 {
  29         char *end = buffer + buflen;
  30         int n;
  31
  32         *--end = '\0';
  33         buflen--;
  34
  35         n = pathname->ncomponents;
  36         while (--n >= 0) {
  37                 const struct nfs4_string *component = &pathname->components[n];
  38                 buflen -= component->len + 1;
  39                 if (buflen < 0)
  40                         goto Elong;
  41                 end -= component->len;
  42                 memcpy(end, component->data, component->len);
  43                 *--end = '/';
  44         }
  45         return end;
  46 Elong:
  47         return ERR_PTR(-ENAMETOOLONG);
  48 }
  49
  50 /*
  51  * Determine the mount path as a string
  52  */
  53 static char *nfs4_path(const struct vfsmount *mnt_parent,
  54                        const struct dentry *dentry,
  55                        char *buffer, ssize_t buflen)
  56 {
  57         const char *srvpath;
  58
  59         srvpath = strchr(mnt_parent->mnt_devname, ':');
  60         if (srvpath)
  61                 srvpath++;
  62         else
  63                 srvpath = mnt_parent->mnt_devname;
  64
  65         return nfs_path(srvpath, mnt_parent->mnt_root, dentry, buffer, buflen);
  66 }
  67
  68 /*
  69  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  70  * believe to be the server path to this dentry
  71  */
  72 static int nfs4_validate_fspath(const struct vfsmount *mnt_parent,
  73                                 const struct dentry *dentry,
  74                                 const struct nfs4_fs_locations *locations,
  75                                 char *page, char *page2)
  76 {
  77         const char *path, *fs_path;
  78
  79         path = nfs4_path(mnt_parent, dentry, page, PAGE_SIZE);
  80         if (IS_ERR(path))
  81                 return PTR_ERR(path);
  82
  83         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
  84         if (IS_ERR(fs_path))
  85                 return PTR_ERR(fs_path);
  86
  87         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
  88                 dprintk("%s: path %s does not begin with fsroot %s\n",
  89                         __func__, path, fs_path);
  90                 return -ENOENT;
  91         }
  92
  93         return 0;
  94 }
  95
  96 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
  97                                      char *page, char *page2,
  98                                      const struct nfs4_fs_location *location)
  99 {
 100         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 101         char *mnt_path;
 102         int page2len;
 103         unsigned int s;
 104
 105         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 106         if (IS_ERR(mnt_path))
 107                 return mnt;
 108         mountdata->mnt_path = mnt_path;
 109         page2 += strlen(mnt_path) + 1;
 110         page2len = PAGE_SIZE - strlen(mnt_path) - 1;
 111
 112         for (s = 0; s < location->nservers; s++) {
 113                 const struct nfs4_string *buf = &location->servers[s];
 114                 struct sockaddr_storage addr;
 115
 116                 if (buf->len <= 0 || buf->len >= PAGE_SIZE)
 117                         continue;
 118
 119                 mountdata->addr = (struct sockaddr *)&addr;
 120
 121                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 122                         continue;
 123                 nfs_parse_ip_address(buf->data, buf->len,
 124                                 mountdata->addr, &mountdata->addrlen);
 125                 if (mountdata->addr->sa_family == AF_UNSPEC)
 126                         continue;
 127                 nfs_set_port(mountdata->addr, NFS_PORT);
 128
 129                 strncpy(page2, buf->data, page2len);
 130                 page2[page2len] = '\0';
 131                 mountdata->hostname = page2;
 132
 133                 snprintf(page, PAGE_SIZE, "%s:%s",
 134                                 mountdata->hostname,
 135                                 mountdata->mnt_path);
 136
 137                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 138                 if (!IS_ERR(mnt))
 139                         break;
 140         }
 141         return mnt;
 142 }
 143
 144 /**
 145  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 146  * @mnt_parent - mountpoint of parent directory
 147  * @dentry - parent directory
 148  * @locations - array of NFSv4 server location information
 149  *
 150  */
 151 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 152                                             const struct dentry *dentry,
 153                                             const struct nfs4_fs_locations *locations)
 154 {
 155         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 156         struct nfs_clone_mount mountdata = {
 157                 .sb = mnt_parent->mnt_sb,
 158                 .dentry = dentry,
 159                 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
 160         };
 161         char *page = NULL, *page2 = NULL;
 162         int loc, error;
 163
 164         if (locations == NULL || locations->nlocations <= 0)
 165                 goto out;
 166
 167         dprintk("%s: referral at %s/%s\n", __func__,
 168                 dentry->d_parent->d_name.name, dentry->d_name.name);
 169
 170         page = (char *) __get_free_page(GFP_USER);
 171         if (!page)
 172                 goto out;
 173
 174         page2 = (char *) __get_free_page(GFP_USER);
 175         if (!page2)
 176                 goto out;
 177
 178         /* Ensure fs path is a prefix of current dentry path */
 179         error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
 180         if (error < 0) {
 181                 mnt = ERR_PTR(error);
 182                 goto out;
 183         }
 184
 185         for (loc = 0; loc < locations->nlocations; loc++) {
 186                 const struct nfs4_fs_location *location = &locations->locations[loc];
 187
 188                 if (location == NULL || location->nservers <= 0 ||
 189                     location->rootpath.ncomponents == 0)
 190                         continue;
 191
 192                 mnt = try_location(&mountdata, page, page2, location);
 193                 if (!IS_ERR(mnt))
 194                         break;
 195         }
 196
 197 out:
 198         free_page((unsigned long) page);
 199         free_page((unsigned long) page2);
 200         dprintk("%s: done\n", __func__);
 201         return mnt;
 202 }
 203
 204 /*
 205  * nfs_do_refmount - handle crossing a referral on server
 206  * @dentry - dentry of referral
 207  * @nd - nameidata info
 208  *
 209  */
 210 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 211 {
 212         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 213         struct dentry *parent;
 214         struct nfs4_fs_locations *fs_locations = NULL;
 215         struct page *page;
 216         int err;
 217
 218         /* BUG_ON(IS_ROOT(dentry)); */
 219         dprintk("%s: enter\n", __func__);
 220
 221         page = alloc_page(GFP_KERNEL);
 222         if (page == NULL)
 223                 goto out;
 224
 225         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 226         if (fs_locations == NULL)
 227                 goto out_free;
 228
 229         /* Get locations */
 230         mnt = ERR_PTR(-ENOENT);
 231
 232         parent = dget_parent(dentry);
 233         dprintk("%s: getting locations for %s/%s\n",
 234                 __func__, parent->d_name.name, dentry->d_name.name);
 235
 236         err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);
 237         dput(parent);
 238         if (err != 0 ||
 239             fs_locations->nlocations <= 0 ||
 240             fs_locations->fs_path.ncomponents <= 0)
 241                 goto out_free;
 242
 243         mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
 244 out_free:
 245         __free_page(page);
 246         kfree(fs_locations);
 247 out:
 248         dprintk("%s: done\n", __func__);
 249         return mnt;
 250 }