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