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 } 266