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   1 /*
   2  * linux/fs/nfs/nfs4namespace.c
   3  *
   4  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
   5  *
   6  * NFSv4 namespace
   7  */
   8
   9 #include <linux/config.h>
  10
  11 #include <linux/dcache.h>
  12 #include <linux/mount.h>
  13 #include <linux/namei.h>
  14 #include <linux/nfs_fs.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
  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 /**
  52  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
  53  * @mnt_parent - mountpoint of parent directory
  54  * @dentry - parent directory
  55  * @fspath - fs path returned in fs_locations
  56  * @mntpath - mount path to new server
  57  * @hostname - hostname of new server
  58  * @addr - host addr of new server
  59  *
  60  */
  61 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
  62                                             const struct dentry *dentry,
  63                                             const struct nfs4_fs_locations *locations)
  64 {
  65         struct vfsmount *mnt = ERR_PTR(-ENOENT);
  66         struct nfs_clone_mount mountdata = {
  67                 .sb = mnt_parent->mnt_sb,
  68                 .dentry = dentry,
  69                 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
  70         };
  71         char *page, *page2;
  72         char *path, *fs_path;
  73         char *devname;
  74         int loc, s;
  75
  76         if (locations == NULL || locations->nlocations <= 0)
  77                 goto out;
  78
  79         dprintk("%s: referral at %s/%s\n", __FUNCTION__,
  80                 dentry->d_parent->d_name.name, dentry->d_name.name);
  81
  82         /* Ensure fs path is a prefix of current dentry path */
  83         page = (char *) __get_free_page(GFP_USER);
  84         if (page == NULL)
  85                 goto out;
  86         page2 = (char *) __get_free_page(GFP_USER);
  87         if (page2 == NULL)
  88                 goto out;
  89
  90         path = nfs4_path(dentry, page, PAGE_SIZE);
  91         if (IS_ERR(path))
  92                 goto out_free;
  93
  94         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
  95         if (IS_ERR(fs_path))
  96                 goto out_free;
  97
  98         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
  99                 dprintk("%s: path %s does not begin with fsroot %s\n", __FUNCTION__, path, fs_path);
 100                 goto out_free;
 101         }
 102
 103         devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
 104         if (IS_ERR(devname)) {
 105                 mnt = (struct vfsmount *)devname;
 106                 goto out_free;
 107         }
 108
 109         loc = 0;
 110         while (loc < locations->nlocations && IS_ERR(mnt)) {
 111                 const struct nfs4_fs_location *location = &locations->locations[loc];
 112                 char *mnt_path;
 113
 114                 if (location == NULL || location->nservers <= 0 ||
 115                     location->rootpath.ncomponents == 0) {
 116                         loc++;
 117                         continue;
 118                 }
 119
 120                 mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 121                 if (IS_ERR(mnt_path)) {
 122                         loc++;
 123                         continue;
 124                 }
 125                 mountdata.mnt_path = mnt_path;
 126
 127                 s = 0;
 128                 while (s < location->nservers) {
 129                         struct sockaddr_in addr = {};
 130
 131                         if (location->servers[s].len <= 0 ||
 132                             valid_ipaddr4(location->servers[s].data) < 0) {
 133                                 s++;
 134                                 continue;
 135                         }
 136
 137                         mountdata.hostname = location->servers[s].data;
 138                         addr.sin_addr.s_addr = in_aton(mountdata.hostname);
 139                         addr.sin_family = AF_INET;
 140                         addr.sin_port = htons(NFS_PORT);
 141                         mountdata.addr = &addr;
 142
 143                         mnt = vfs_kern_mount(&nfs_referral_nfs4_fs_type, 0, devname, &mountdata);
 144                         if (!IS_ERR(mnt)) {
 145                                 break;
 146                         }
 147                         s++;
 148                 }
 149                 loc++;
 150         }
 151
 152 out_free:
 153         free_page((unsigned long)page);
 154         free_page((unsigned long)page2);
 155 out:
 156         dprintk("%s: done\n", __FUNCTION__);
 157         return mnt;
 158 }
 159
 160 /*
 161  * nfs_do_refmount - handle crossing a referral on server
 162  * @dentry - dentry of referral
 163  * @nd - nameidata info
 164  *
 165  */
 166 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 167 {
 168         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 169         struct dentry *parent;
 170         struct nfs4_fs_locations *fs_locations = NULL;
 171         struct page *page;
 172         int err;
 173
 174         /* BUG_ON(IS_ROOT(dentry)); */
 175         dprintk("%s: enter\n", __FUNCTION__);
 176
 177         page = alloc_page(GFP_KERNEL);
 178         if (page == NULL)
 179                 goto out;
 180
 181         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 182         if (fs_locations == NULL)
 183                 goto out_free;
 184
 185         /* Get locations */
 186         parent = dget_parent(dentry);
 187         dprintk("%s: getting locations for %s/%s\n", __FUNCTION__, parent->d_name.name, dentry->d_name.name);
 188         err = nfs4_proc_fs_locations(parent->d_inode, dentry, fs_locations, page);
 189         dput(parent);
 190         if (err != 0 || fs_locations->nlocations <= 0 ||
 191             fs_locations->fs_path.ncomponents <= 0)
 192                 goto out_free;
 193
 194         mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
 195 out_free:
 196         __free_page(page);
 197         kfree(fs_locations);
 198 out:
 199         dprintk("%s: done\n", __FUNCTION__);
 200         return mnt;
 201 }