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(const struct vfsmount *mnt_parent,
  58                        const struct dentry *dentry,
  59                        char *buffer, ssize_t buflen)
  60 {
  61         const char *srvpath;
  62
  63         srvpath = strchr(mnt_parent->mnt_devname, ':');
  64         if (srvpath)
  65                 srvpath++;
  66         else
  67                 srvpath = mnt_parent->mnt_devname;
  68
  69         return nfs_path(srvpath, mnt_parent->mnt_root, dentry, buffer, buflen);
  70 }
  71
  72 /*
  73  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  74  * believe to be the server path to this dentry
  75  */
  76 static int nfs4_validate_fspath(const struct vfsmount *mnt_parent,
  77                                 const struct dentry *dentry,
  78                                 const struct nfs4_fs_locations *locations,
  79                                 char *page, char *page2)
  80 {
  81         const char *path, *fs_path;
  82
  83         path = nfs4_path(mnt_parent, dentry, page, PAGE_SIZE);
  84         if (IS_ERR(path))
  85                 return PTR_ERR(path);
  86
  87         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
  88         if (IS_ERR(fs_path))
  89                 return PTR_ERR(fs_path);
  90
  91         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
  92                 dprintk("%s: path %s does not begin with fsroot %s\n",
  93                         __func__, path, fs_path);
  94                 return -ENOENT;
  95         }
  96
  97         return 0;
  98 }
  99
 100 static size_t nfs_parse_server_name(char *string, size_t len,
 101                 struct sockaddr *sa, size_t salen)
 102 {
 103         ssize_t ret;
 104
 105         ret = rpc_pton(string, len, sa, salen);
 106         if (ret == 0) {
 107                 ret = nfs_dns_resolve_name(string, len, sa, salen);
 108                 if (ret < 0)
 109                         ret = 0;
 110         }
 111         return ret;
 112 }
 113
 114 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 115                                      char *page, char *page2,
 116                                      const struct nfs4_fs_location *location)
 117 {
 118         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 119         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 120         char *mnt_path;
 121         unsigned int maxbuflen;
 122         unsigned int s;
 123
 124         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 125         if (IS_ERR(mnt_path))
 126                 return ERR_CAST(mnt_path);
 127         mountdata->mnt_path = mnt_path;
 128         maxbuflen = mnt_path - 1 - page2;
 129
 130         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 131         if (mountdata->addr == NULL)
 132                 return ERR_PTR(-ENOMEM);
 133
 134         for (s = 0; s < location->nservers; s++) {
 135                 const struct nfs4_string *buf = &location->servers[s];
 136
 137                 if (buf->len <= 0 || buf->len >= maxbuflen)
 138                         continue;
 139
 140                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 141                         continue;
 142
 143                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 144                                 mountdata->addr, addr_bufsize);
 145                 if (mountdata->addrlen == 0)
 146                         continue;
 147
 148                 rpc_set_port(mountdata->addr, NFS_PORT);
 149
 150                 memcpy(page2, buf->data, buf->len);
 151                 page2[buf->len] = '\0';
 152                 mountdata->hostname = page2;
 153
 154                 snprintf(page, PAGE_SIZE, "%s:%s",
 155                                 mountdata->hostname,
 156                                 mountdata->mnt_path);
 157
 158                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 159                 if (!IS_ERR(mnt))
 160                         break;
 161         }
 162         kfree(mountdata->addr);
 163         return mnt;
 164 }
 165
 166 /**
 167  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 168  * @mnt_parent - mountpoint of parent directory
 169  * @dentry - parent directory
 170  * @locations - array of NFSv4 server location information
 171  *
 172  */
 173 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 174                                             const struct dentry *dentry,
 175                                             const struct nfs4_fs_locations *locations)
 176 {
 177         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 178         struct nfs_clone_mount mountdata = {
 179                 .sb = mnt_parent->mnt_sb,
 180                 .dentry = dentry,
 181                 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
 182         };
 183         char *page = NULL, *page2 = NULL;
 184         int loc, error;
 185
 186         if (locations == NULL || locations->nlocations <= 0)
 187                 goto out;
 188
 189         dprintk("%s: referral at %s/%s\n", __func__,
 190                 dentry->d_parent->d_name.name, dentry->d_name.name);
 191
 192         page = (char *) __get_free_page(GFP_USER);
 193         if (!page)
 194                 goto out;
 195
 196         page2 = (char *) __get_free_page(GFP_USER);
 197         if (!page2)
 198                 goto out;
 199
 200         /* Ensure fs path is a prefix of current dentry path */
 201         error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
 202         if (error < 0) {
 203                 mnt = ERR_PTR(error);
 204                 goto out;
 205         }
 206
 207         for (loc = 0; loc < locations->nlocations; loc++) {
 208                 const struct nfs4_fs_location *location = &locations->locations[loc];
 209
 210                 if (location == NULL || location->nservers <= 0 ||
 211                     location->rootpath.ncomponents == 0)
 212                         continue;
 213
 214                 mnt = try_location(&mountdata, page, page2, location);
 215                 if (!IS_ERR(mnt))
 216                         break;
 217         }
 218
 219 out:
 220         free_page((unsigned long) page);
 221         free_page((unsigned long) page2);
 222         dprintk("%s: done\n", __func__);
 223         return mnt;
 224 }
 225
 226 /*
 227  * nfs_do_refmount - handle crossing a referral on server
 228  * @mnt_parent - mountpoint of referral
 229  * @dentry - dentry of referral
 230  *
 231  */
 232 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 233 {
 234         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 235         struct dentry *parent;
 236         struct nfs4_fs_locations *fs_locations = NULL;
 237         struct page *page;
 238         int err;
 239
 240         /* BUG_ON(IS_ROOT(dentry)); */
 241         dprintk("%s: enter\n", __func__);
 242
 243         page = alloc_page(GFP_KERNEL);
 244         if (page == NULL)
 245                 goto out;
 246
 247         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 248         if (fs_locations == NULL)
 249                 goto out_free;
 250
 251         /* Get locations */
 252         mnt = ERR_PTR(-ENOENT);
 253
 254         parent = dget_parent(dentry);
 255         dprintk("%s: getting locations for %s/%s\n",
 256                 __func__, parent->d_name.name, dentry->d_name.name);
 257
 258         err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);
 259         dput(parent);
 260         if (err != 0 ||
 261             fs_locations->nlocations <= 0 ||
 262             fs_locations->fs_path.ncomponents <= 0)
 263                 goto out_free;
 264
 265         mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
 266 out_free:
 267         __free_page(page);
 268         kfree(fs_locations);
 269 out:
 270         dprintk("%s: done\n", __func__);
 271         return mnt;
 272 }