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, struct nfs_server *server)
  98 {
  99         struct net *net = rpc_net_ns(server->client);
 100         ssize_t ret;
 101
 102         ret = rpc_pton(net, string, len, sa, salen);
 103         if (ret == 0) {
 104                 ret = nfs_dns_resolve_name(net, string, len, sa, salen);
 105                 if (ret < 0)
 106                         ret = 0;
 107         }
 108         return ret;
 109 }
 110
 111 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 112                                      char *page, char *page2,
 113                                      const struct nfs4_fs_location *location)
 114 {
 115         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 116         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 117         char *mnt_path;
 118         unsigned int maxbuflen;
 119         unsigned int s;
 120
 121         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 122         if (IS_ERR(mnt_path))
 123                 return ERR_CAST(mnt_path);
 124         mountdata->mnt_path = mnt_path;
 125         maxbuflen = mnt_path - 1 - page2;
 126
 127         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 128         if (mountdata->addr == NULL)
 129                 return ERR_PTR(-ENOMEM);
 130
 131         for (s = 0; s < location->nservers; s++) {
 132                 const struct nfs4_string *buf = &location->servers[s];
 133
 134                 if (buf->len <= 0 || buf->len >= maxbuflen)
 135                         continue;
 136
 137                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 138                         continue;
 139
 140                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 141                                 mountdata->addr, addr_bufsize,
 142                                 NFS_SB(mountdata->sb));
 143                 if (mountdata->addrlen == 0)
 144                         continue;
 145
 146                 rpc_set_port(mountdata->addr, NFS_PORT);
 147
 148                 memcpy(page2, buf->data, buf->len);
 149                 page2[buf->len] = '\0';
 150                 mountdata->hostname = page2;
 151
 152                 snprintf(page, PAGE_SIZE, "%s:%s",
 153                                 mountdata->hostname,
 154                                 mountdata->mnt_path);
 155
 156                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 157                 if (!IS_ERR(mnt))
 158                         break;
 159         }
 160         kfree(mountdata->addr);
 161         return mnt;
 162 }
 163
 164 /**
 165  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 166  * @dentry - parent directory
 167  * @locations - array of NFSv4 server location information
 168  *
 169  */
 170 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 171                                             const struct nfs4_fs_locations *locations)
 172 {
 173         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 174         struct nfs_clone_mount mountdata = {
 175                 .sb = dentry->d_sb,
 176                 .dentry = dentry,
 177                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 178         };
 179         char *page = NULL, *page2 = NULL;
 180         int loc, error;
 181
 182         if (locations == NULL || locations->nlocations <= 0)
 183                 goto out;
 184
 185         dprintk("%s: referral at %s/%s\n", __func__,
 186                 dentry->d_parent->d_name.name, dentry->d_name.name);
 187
 188         page = (char *) __get_free_page(GFP_USER);
 189         if (!page)
 190                 goto out;
 191
 192         page2 = (char *) __get_free_page(GFP_USER);
 193         if (!page2)
 194                 goto out;
 195
 196         /* Ensure fs path is a prefix of current dentry path */
 197         error = nfs4_validate_fspath(dentry, locations, page, page2);
 198         if (error < 0) {
 199                 mnt = ERR_PTR(error);
 200                 goto out;
 201         }
 202
 203         for (loc = 0; loc < locations->nlocations; loc++) {
 204                 const struct nfs4_fs_location *location = &locations->locations[loc];
 205
 206                 if (location == NULL || location->nservers <= 0 ||
 207                     location->rootpath.ncomponents == 0)
 208                         continue;
 209
 210                 mnt = try_location(&mountdata, page, page2, location);
 211                 if (!IS_ERR(mnt))
 212                         break;
 213         }
 214
 215 out:
 216         free_page((unsigned long) page);
 217         free_page((unsigned long) page2);
 218         dprintk("%s: done\n", __func__);
 219         return mnt;
 220 }
 221
 222 /*
 223  * nfs_do_refmount - handle crossing a referral on server
 224  * @dentry - dentry of referral
 225  *
 226  */
 227 struct vfsmount *nfs_do_refmount(struct dentry *dentry)
 228 {
 229         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 230         struct dentry *parent;
 231         struct nfs4_fs_locations *fs_locations = NULL;
 232         struct page *page;
 233         int err;
 234
 235         /* BUG_ON(IS_ROOT(dentry)); */
 236         dprintk("%s: enter\n", __func__);
 237
 238         page = alloc_page(GFP_KERNEL);
 239         if (page == NULL)
 240                 goto out;
 241
 242         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 243         if (fs_locations == NULL)
 244                 goto out_free;
 245
 246         /* Get locations */
 247         mnt = ERR_PTR(-ENOENT);
 248
 249         parent = dget_parent(dentry);
 250         dprintk("%s: getting locations for %s/%s\n",
 251                 __func__, parent->d_name.name, dentry->d_name.name);
 252
 253         err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);
 254         dput(parent);
 255         if (err != 0 ||
 256             fs_locations->nlocations <= 0 ||
 257             fs_locations->fs_path.ncomponents <= 0)
 258                 goto out_free;
 259
 260         mnt = nfs_follow_referral(dentry, fs_locations);
 261 out_free:
 262         __free_page(page);
 263         kfree(fs_locations);
 264 out:
 265         dprintk("%s: done\n", __func__);
 266         return mnt;
 267 }