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 /*
  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 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 114                                      char *page, char *page2,
 115                                      const struct nfs4_fs_location *location)
 116 {
 117         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 118         char *mnt_path;
 119         unsigned int s = 0;
 120
 121         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 122         if (IS_ERR(mnt_path))
 123                 return mnt;
 124         mountdata->mnt_path = mnt_path;
 125
 126         while (s < location->nservers) {
 127                 struct sockaddr_in addr = {
 128                         .sin_family     = AF_INET,
 129                         .sin_port       = htons(NFS_PORT),
 130                 };
 131
 132                 if (location->servers[s].len <= 0 ||
 133                     valid_ipaddr4(location->servers[s].data) < 0) {
 134                         s++;
 135                         continue;
 136                 }
 137
 138                 mountdata->hostname = location->servers[s].data;
 139                 addr.sin_addr.s_addr = in_aton(mountdata->hostname),
 140                 mountdata->addr = (struct sockaddr *)&addr;
 141                 mountdata->addrlen = sizeof(addr);
 142
 143                 snprintf(page, PAGE_SIZE, "%s:%s",
 144                                 mountdata->hostname,
 145                                 mountdata->mnt_path);
 146
 147                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 148                 if (!IS_ERR(mnt))
 149                         break;
 150                 s++;
 151         }
 152         return mnt;
 153 }
 154
 155 /**
 156  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 157  * @mnt_parent - mountpoint of parent directory
 158  * @dentry - parent directory
 159  * @locations - array of NFSv4 server location information
 160  *
 161  */
 162 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 163                                             const struct dentry *dentry,
 164                                             const struct nfs4_fs_locations *locations)
 165 {
 166         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 167         struct nfs_clone_mount mountdata = {
 168                 .sb = mnt_parent->mnt_sb,
 169                 .dentry = dentry,
 170                 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
 171         };
 172         char *page = NULL, *page2 = NULL;
 173         int loc, error;
 174
 175         if (locations == NULL || locations->nlocations <= 0)
 176                 goto out;
 177
 178         dprintk("%s: referral at %s/%s\n", __func__,
 179                 dentry->d_parent->d_name.name, dentry->d_name.name);
 180
 181         page = (char *) __get_free_page(GFP_USER);
 182         if (!page)
 183                 goto out;
 184
 185         page2 = (char *) __get_free_page(GFP_USER);
 186         if (!page2)
 187                 goto out;
 188
 189         /* Ensure fs path is a prefix of current dentry path */
 190         error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
 191         if (error < 0) {
 192                 mnt = ERR_PTR(error);
 193                 goto out;
 194         }
 195
 196         loc = 0;
 197         while (loc < locations->nlocations) {
 198                 const struct nfs4_fs_location *location = &locations->locations[loc];
 199
 200                 if (location == NULL || location->nservers <= 0 ||
 201                     location->rootpath.ncomponents == 0) {
 202                         loc++;
 203                         continue;
 204                 }
 205
 206                 mnt = try_location(&mountdata, page, page2, location);
 207                 if (!IS_ERR(mnt))
 208                         break;
 209                 loc++;
 210         }
 211
 212 out:
 213         free_page((unsigned long) page);
 214         free_page((unsigned long) page2);
 215         dprintk("%s: done\n", __func__);
 216         return mnt;
 217 }
 218
 219 /*
 220  * nfs_do_refmount - handle crossing a referral on server
 221  * @dentry - dentry of referral
 222  * @nd - nameidata info
 223  *
 224  */
 225 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 226 {
 227         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 228         struct dentry *parent;
 229         struct nfs4_fs_locations *fs_locations = NULL;
 230         struct page *page;
 231         int err;
 232
 233         /* BUG_ON(IS_ROOT(dentry)); */
 234         dprintk("%s: enter\n", __func__);
 235
 236         page = alloc_page(GFP_KERNEL);
 237         if (page == NULL)
 238                 goto out;
 239
 240         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 241         if (fs_locations == NULL)
 242                 goto out_free;
 243
 244         /* Get locations */
 245         mnt = ERR_PTR(-ENOENT);
 246
 247         parent = dget_parent(dentry);
 248         dprintk("%s: getting locations for %s/%s\n",
 249                 __func__, parent->d_name.name, dentry->d_name.name);
 250
 251         err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);
 252         dput(parent);
 253         if (err != 0 ||
 254             fs_locations->nlocations <= 0 ||
 255             fs_locations->fs_path.ncomponents <= 0)
 256                 goto out_free;
 257
 258         mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
 259 out_free:
 260         __free_page(page);
 261         kfree(fs_locations);
 262 out:
 263         dprintk("%s: done\n", __func__);
 264         return mnt;
 265 }