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   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                         __FUNCTION__, path, fs_path);
  90                 return -ENOENT;
  91         }
  92
  93         return 0;
  94 }
  95
  96 /*
  97  * Check if the string represents a "valid" IPv4 address
  98  */
  99 static inline int valid_ipaddr4(const char *buf)
 100 {
 101         int rc, count, in[4];
 102
 103         rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
 104         if (rc != 4)
 105                 return -EINVAL;
 106         for (count = 0; count < 4; count++) {
 107                 if (in[count] > 255)
 108                         return -EINVAL;
 109         }
 110         return 0;
 111 }
 112
 113 /**
 114  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 115  * @mnt_parent - mountpoint of parent directory
 116  * @dentry - parent directory
 117  * @fspath - fs path returned in fs_locations
 118  * @mntpath - mount path to new server
 119  * @hostname - hostname of new server
 120  * @addr - host addr of new server
 121  *
 122  */
 123 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 124                                             const struct dentry *dentry,
 125                                             const struct nfs4_fs_locations *locations)
 126 {
 127         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 128         struct nfs_clone_mount mountdata = {
 129                 .sb = mnt_parent->mnt_sb,
 130                 .dentry = dentry,
 131                 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
 132         };
 133         char *page = NULL, *page2 = NULL;
 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         loc = 0;
 158         while (loc < locations->nlocations && IS_ERR(mnt)) {
 159                 const struct nfs4_fs_location *location = &locations->locations[loc];
 160                 char *mnt_path;
 161
 162                 if (location == NULL || location->nservers <= 0 ||
 163                     location->rootpath.ncomponents == 0) {
 164                         loc++;
 165                         continue;
 166                 }
 167
 168                 mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 169                 if (IS_ERR(mnt_path)) {
 170                         loc++;
 171                         continue;
 172                 }
 173                 mountdata.mnt_path = mnt_path;
 174
 175                 s = 0;
 176                 while (s < location->nservers) {
 177                         struct sockaddr_in addr = {};
 178
 179                         if (location->servers[s].len <= 0 ||
 180                             valid_ipaddr4(location->servers[s].data) < 0) {
 181                                 s++;
 182                                 continue;
 183                         }
 184
 185                         mountdata.hostname = location->servers[s].data;
 186                         addr.sin_addr.s_addr = in_aton(mountdata.hostname);
 187                         addr.sin_family = AF_INET;
 188                         addr.sin_port = htons(NFS_PORT);
 189                         mountdata.addr = &addr;
 190
 191                         snprintf(page, PAGE_SIZE, "%s:%s",
 192                                         mountdata.hostname,
 193                                         mountdata.mnt_path);
 194
 195                         mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, &mountdata);
 196                         if (!IS_ERR(mnt)) {
 197                                 break;
 198                         }
 199                         s++;
 200                 }
 201                 loc++;
 202         }
 203
 204 out:
 205         free_page((unsigned long) page);
 206         free_page((unsigned long) page2);
 207         dprintk("%s: done\n", __FUNCTION__);
 208         return mnt;
 209 }
 210
 211 /*
 212  * nfs_do_refmount - handle crossing a referral on server
 213  * @dentry - dentry of referral
 214  * @nd - nameidata info
 215  *
 216  */
 217 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 218 {
 219         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 220         struct dentry *parent;
 221         struct nfs4_fs_locations *fs_locations = NULL;
 222         struct page *page;
 223         int err;
 224
 225         /* BUG_ON(IS_ROOT(dentry)); */
 226         dprintk("%s: enter\n", __FUNCTION__);
 227
 228         page = alloc_page(GFP_KERNEL);
 229         if (page == NULL)
 230                 goto out;
 231
 232         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 233         if (fs_locations == NULL)
 234                 goto out_free;
 235
 236         /* Get locations */
 237         mnt = ERR_PTR(-ENOENT);
 238
 239         parent = dget_parent(dentry);
 240         dprintk("%s: getting locations for %s/%s\n",
 241                 __FUNCTION__, parent->d_name.name, dentry->d_name.name);
 242
 243         err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);
 244         dput(parent);
 245         if (err != 0 ||
 246             fs_locations->nlocations <= 0 ||
 247             fs_locations->fs_path.ncomponents <= 0)
 248                 goto out_free;
 249
 250         mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
 251 out_free:
 252         __free_page(page);
 253         kfree(fs_locations);
 254 out:
 255         dprintk("%s: done\n", __FUNCTION__);
 256         return mnt;
 257 }