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/slab.h>
  15 #include <linux/string.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/vfs.h>
  18 #include <linux/inet.h>
  19 #include "internal.h"
  20 #include "nfs4_fs.h"
  21 #include "dns_resolve.h"
  22
  23 #define NFSDBG_FACILITY         NFSDBG_VFS
  24
  25 /*
  26  * Convert the NFSv4 pathname components into a standard posix path.
  27  *
  28  * Note that the resulting string will be placed at the end of the buffer
  29  */
  30 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  31                                          char *buffer, ssize_t buflen)
  32 {
  33         char *end = buffer + buflen;
  34         int n;
  35
  36         *--end = '\0';
  37         buflen--;
  38
  39         n = pathname->ncomponents;
  40         while (--n >= 0) {
  41                 const struct nfs4_string *component = &pathname->components[n];
  42                 buflen -= component->len + 1;
  43                 if (buflen < 0)
  44                         goto Elong;
  45                 end -= component->len;
  46                 memcpy(end, component->data, component->len);
  47                 *--end = '/';
  48         }
  49         return end;
  50 Elong:
  51         return ERR_PTR(-ENAMETOOLONG);
  52 }
  53
  54 /*
  55  * Determine the mount path as a string
  56  */
  57 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
  58 {
  59         char *limit;
  60         char *path = nfs_path(&limit, dentry, buffer, buflen);
  61         if (!IS_ERR(path)) {
  62                 char *colon = strchr(path, ':');
  63                 if (colon && colon < limit)
  64                         path = colon + 1;
  65         }
  66         return path;
  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(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(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 static size_t nfs_parse_server_name(char *string, size_t len,
  97                 struct sockaddr *sa, size_t salen)
  98 {
  99         ssize_t ret;
 100
 101         ret = rpc_pton(string, len, sa, salen);
 102         if (ret == 0) {
 103                 ret = nfs_dns_resolve_name(string, len, sa, salen);
 104                 if (ret < 0)
 105                         ret = 0;
 106         }
 107         return ret;
 108 }
 109
 110 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 111                                      char *page, char *page2,
 112                                      const struct nfs4_fs_location *location)
 113 {
 114         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 115         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 116         char *mnt_path;
 117         unsigned int maxbuflen;
 118         unsigned int s;
 119
 120         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 121         if (IS_ERR(mnt_path))
 122                 return ERR_CAST(mnt_path);
 123         mountdata->mnt_path = mnt_path;
 124         maxbuflen = mnt_path - 1 - page2;
 125
 126         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 127         if (mountdata->addr == NULL)
 128                 return ERR_PTR(-ENOMEM);
 129
 130         for (s = 0; s < location->nservers; s++) {
 131                 const struct nfs4_string *buf = &location->servers[s];
 132
 133                 if (buf->len <= 0 || buf->len >= maxbuflen)
 134                         continue;
 135
 136                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 137                         continue;
 138
 139                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 140                                 mountdata->addr, addr_bufsize);
 141                 if (mountdata->addrlen == 0)
 142                         continue;
 143
 144                 rpc_set_port(mountdata->addr, NFS_PORT);
 145
 146                 memcpy(page2, buf->data, buf->len);
 147                 page2[buf->len] = '\0';
 148                 mountdata->hostname = page2;
 149
 150                 snprintf(page, PAGE_SIZE, "%s:%s",
 151                                 mountdata->hostname,
 152                                 mountdata->mnt_path);
 153
 154                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 155                 if (!IS_ERR(mnt))
 156                         break;
 157         }
 158         kfree(mountdata->addr);
 159         return mnt;
 160 }
 161
 162 /**
 163  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 164  * @dentry - parent directory
 165  * @locations - array of NFSv4 server location information
 166  *
 167  */
 168 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 169                                             const struct nfs4_fs_locations *locations)
 170 {
 171         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 172         struct nfs_clone_mount mountdata = {
 173                 .sb = dentry->d_sb,
 174                 .dentry = dentry,
 175                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 176         };
 177         char *page = NULL, *page2 = NULL;
 178         int loc, error;
 179
 180         if (locations == NULL || locations->nlocations <= 0)
 181                 goto out;
 182
 183         dprintk("%s: referral at %s/%s\n", __func__,
 184                 dentry->d_parent->d_name.name, dentry->d_name.name);
 185
 186         page = (char *) __get_free_page(GFP_USER);
 187         if (!page)
 188                 goto out;
 189
 190         page2 = (char *) __get_free_page(GFP_USER);
 191         if (!page2)
 192                 goto out;
 193
 194         /* Ensure fs path is a prefix of current dentry path */
 195         error = nfs4_validate_fspath(dentry, locations, page, page2);
 196         if (error < 0) {
 197                 mnt = ERR_PTR(error);
 198                 goto out;
 199         }
 200
 201         for (loc = 0; loc < locations->nlocations; loc++) {
 202                 const struct nfs4_fs_location *location = &locations->locations[loc];
 203
 204                 if (location == NULL || location->nservers <= 0 ||
 205                     location->rootpath.ncomponents == 0)
 206                         continue;
 207
 208                 mnt = try_location(&mountdata, page, page2, location);
 209                 if (!IS_ERR(mnt))
 210                         break;
 211         }
 212
 213 out:
 214         free_page((unsigned long) page);
 215         free_page((unsigned long) page2);
 216         dprintk("%s: done\n", __func__);
 217         return mnt;
 218 }
 219
 220 /*
 221  * nfs_do_refmount - handle crossing a referral on server
 222  * @dentry - dentry of referral
 223  *
 224  */
 225 struct vfsmount *nfs_do_refmount(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(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 }