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