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/config.h>
  11
  12 #include <linux/dcache.h>
  13 #include <linux/mount.h>
  14 #include <linux/namei.h>
  15 #include <linux/nfs_fs.h>
  16 #include <linux/string.h>
  17 #include <linux/sunrpc/clnt.h>
  18 #include <linux/vfs.h>
  19 #include <linux/inet.h>
  20 #include "internal.h"
  21
  22 #define NFSDBG_FACILITY         NFSDBG_VFS
  23
  24 /*
  25  * Check if fs_root is valid
  26  */
  27 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  28                                          char *buffer, ssize_t buflen)
  29 {
  30         char *end = buffer + buflen;
  31         int n;
  32
  33         *--end = '\0';
  34         buflen--;
  35
  36         n = pathname->ncomponents;
  37         while (--n >= 0) {
  38                 const struct nfs4_string *component = &pathname->components[n];
  39                 buflen -= component->len + 1;
  40                 if (buflen < 0)
  41                         goto Elong;
  42                 end -= component->len;
  43                 memcpy(end, component->data, component->len);
  44                 *--end = '/';
  45         }
  46         return end;
  47 Elong:
  48         return ERR_PTR(-ENAMETOOLONG);
  49 }
  50
  51 /*
  52  * Determine the mount path as a string
  53  */
  54 static char *nfs4_path(const struct vfsmount *mnt_parent,
  55                        const struct dentry *dentry,
  56                        char *buffer, ssize_t buflen)
  57 {
  58         const char *srvpath;
  59
  60         srvpath = strchr(mnt_parent->mnt_devname, ':');
  61         if (srvpath)
  62                 srvpath++;
  63         else
  64                 srvpath = mnt_parent->mnt_devname;
  65
  66         return nfs_path(srvpath, mnt_parent->mnt_root, dentry, buffer, buflen);
  67 }
  68
  69 /*
  70  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  71  * believe to be the server path to this dentry
  72  */
  73 static int nfs4_validate_fspath(const struct vfsmount *mnt_parent,
  74                                 const struct dentry *dentry,
  75                                 const struct nfs4_fs_locations *locations,
  76                                 char *page, char *page2)
  77 {
  78         const char *path, *fs_path;
  79
  80         path = nfs4_path(mnt_parent, dentry, page, PAGE_SIZE);
  81         if (IS_ERR(path))
  82                 return PTR_ERR(path);
  83
  84         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
  85         if (IS_ERR(fs_path))
  86                 return PTR_ERR(fs_path);
  87
  88         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
  89                 dprintk("%s: path %s does not begin with fsroot %s\n",
  90                         __FUNCTION__, path, fs_path);
  91                 return -ENOENT;
  92         }
  93
  94         return 0;
  95 }
  96
  97 /*
  98  * Check if the string represents a "valid" IPv4 address
  99  */
 100 static inline int valid_ipaddr4(const char *buf)
 101 {
 102         int rc, count, in[4];
 103
 104         rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
 105         if (rc != 4)
 106                 return -EINVAL;
 107         for (count = 0; count < 4; count++) {
 108                 if (in[count] > 255)
 109                         return -EINVAL;
 110         }
 111         return 0;
 112 }
 113
 114 /**
 115  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 116  * @mnt_parent - mountpoint of parent directory
 117  * @dentry - parent directory
 118  * @fspath - fs path returned in fs_locations
 119  * @mntpath - mount path to new server
 120  * @hostname - hostname of new server
 121  * @addr - host addr of new server
 122  *
 123  */
 124 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 125                                             const struct dentry *dentry,
 126                                             const struct nfs4_fs_locations *locations)
 127 {
 128         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 129         struct nfs_clone_mount mountdata = {
 130                 .sb = mnt_parent->mnt_sb,
 131                 .dentry = dentry,
 132                 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
 133         };
 134         char *page = NULL, *page2 = NULL;
 135         char *devname;
 136         int loc, s, error;
 137
 138         if (locations == NULL || locations->nlocations <= 0)
 139                 goto out;
 140
 141         dprintk("%s: referral at %s/%s\n", __FUNCTION__,
 142                 dentry->d_parent->d_name.name, dentry->d_name.name);
 143
 144         page = (char *) __get_free_page(GFP_USER);
 145         if (!page)
 146                 goto out;
 147
 148         page2 = (char *) __get_free_page(GFP_USER);
 149         if (!page2)
 150                 goto out;
 151
 152         /* Ensure fs path is a prefix of current dentry path */
 153         error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
 154         if (error < 0) {
 155                 mnt = ERR_PTR(error);
 156                 goto out;
 157         }
 158
 159         devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
 160         if (IS_ERR(devname)) {
 161                 mnt = (struct vfsmount *)devname;
 162                 goto out;
 163         }
 164
 165         loc = 0;
 166         while (loc < locations->nlocations && IS_ERR(mnt)) {
 167                 const struct nfs4_fs_location *location = &locations->locations[loc];
 168                 char *mnt_path;
 169
 170                 if (location == NULL || location->nservers <= 0 ||
 171                     location->rootpath.ncomponents == 0) {
 172                         loc++;
 173                         continue;
 174                 }
 175
 176                 mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 177                 if (IS_ERR(mnt_path)) {
 178                         loc++;
 179                         continue;
 180                 }
 181                 mountdata.mnt_path = mnt_path;
 182
 183                 s = 0;
 184                 while (s < location->nservers) {
 185                         struct sockaddr_in addr = {};
 186
 187                         if (location->servers[s].len <= 0 ||
 188                             valid_ipaddr4(location->servers[s].data) < 0) {
 189                                 s++;
 190                                 continue;
 191                         }
 192
 193                         mountdata.hostname = location->servers[s].data;
 194                         addr.sin_addr.s_addr = in_aton(mountdata.hostname);
 195                         addr.sin_family = AF_INET;
 196                         addr.sin_port = htons(NFS_PORT);
 197                         mountdata.addr = &addr;
 198
 199                         mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, devname, &mountdata);
 200                         if (!IS_ERR(mnt)) {
 201                                 break;
 202                         }
 203                         s++;
 204                 }
 205                 loc++;
 206         }
 207
 208 out:
 209         free_page((unsigned long) page);
 210         free_page((unsigned long) page2);
 211         dprintk("%s: done\n", __FUNCTION__);
 212         return mnt;
 213 }
 214
 215 /*
 216  * nfs_do_refmount - handle crossing a referral on server
 217  * @dentry - dentry of referral
 218  * @nd - nameidata info
 219  *
 220  */
 221 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 222 {
 223         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 224         struct dentry *parent;
 225         struct nfs4_fs_locations *fs_locations = NULL;
 226         struct page *page;
 227         int err;
 228
 229         /* BUG_ON(IS_ROOT(dentry)); */
 230         dprintk("%s: enter\n", __FUNCTION__);
 231
 232         page = alloc_page(GFP_KERNEL);
 233         if (page == NULL)
 234                 goto out;
 235
 236         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 237         if (fs_locations == NULL)
 238                 goto out_free;
 239
 240         /* Get locations */
 241         mnt = ERR_PTR(-ENOENT);
 242
 243         parent = dget_parent(dentry);
 244         dprintk("%s: getting locations for %s/%s\n",
 245                 __FUNCTION__, parent->d_name.name, dentry->d_name.name);
 246
 247         err = nfs4_proc_fs_locations(parent->d_inode, dentry, fs_locations, page);
 248         dput(parent);
 249         if (err != 0 ||
 250             fs_locations->nlocations <= 0 ||
 251             fs_locations->fs_path.ncomponents <= 0)
 252                 goto out_free;
 253
 254         mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
 255 out_free:
 256         __free_page(page);
 257         kfree(fs_locations);
 258 out:
 259         dprintk("%s: done\n", __FUNCTION__);
 260         return mnt;
 261 }