1 /* 2 * Copyright (C) 1995, 1996 Gero Kuhlmann <gero@gkminix.han.de> 3 * 4 * Allow an NFS filesystem to be mounted as root. The way this works is: 5 * (1) Use the IP autoconfig mechanism to set local IP addresses and routes. 6 * (2) Construct the device string and the options string using DHCP 7 * option 17 and/or kernel command line options. 8 * (3) When mount_root() sets up the root file system, pass these strings 9 * to the NFS client's regular mount interface via sys_mount(). 10 * 11 * 12 * Changes: 13 * 14 * Alan Cox : Removed get_address name clash with FPU. 15 * Alan Cox : Reformatted a bit. 16 * Gero Kuhlmann : Code cleanup 17 * Michael Rausch : Fixed recognition of an incoming RARP answer. 18 * Martin Mares : (2.0) Auto-configuration via BOOTP supported. 19 * Martin Mares : Manual selection of interface & BOOTP/RARP. 20 * Martin Mares : Using network routes instead of host routes, 21 * allowing the default configuration to be used 22 * for normal operation of the host. 23 * Martin Mares : Randomized timer with exponential backoff 24 * installed to minimize network congestion. 25 * Martin Mares : Code cleanup. 26 * Martin Mares : (2.1) BOOTP and RARP made configuration options. 27 * Martin Mares : Server hostname generation fixed. 28 * Gerd Knorr : Fixed wired inode handling 29 * Martin Mares : (2.2) "0.0.0.0" addresses from command line ignored. 30 * Martin Mares : RARP replies not tested for server address. 31 * Gero Kuhlmann : (2.3) Some bug fixes and code cleanup again (please 32 * send me your new patches _before_ bothering 33 * Linus so that I don' always have to cleanup 34 * _afterwards_ - thanks) 35 * Gero Kuhlmann : Last changes of Martin Mares undone. 36 * Gero Kuhlmann : RARP replies are tested for specified server 37 * again. However, it's now possible to have 38 * different RARP and NFS servers. 39 * Gero Kuhlmann : "0.0.0.0" addresses from command line are 40 * now mapped to INADDR_NONE. 41 * Gero Kuhlmann : Fixed a bug which prevented BOOTP path name 42 * from being used (thanks to Leo Spiekman) 43 * Andy Walker : Allow to specify the NFS server in nfs_root 44 * without giving a path name 45 * Swen Thümmler : Allow to specify the NFS options in nfs_root 46 * without giving a path name. Fix BOOTP request 47 * for domainname (domainname is NIS domain, not 48 * DNS domain!). Skip dummy devices for BOOTP. 49 * Jacek Zapala : Fixed a bug which prevented server-ip address 50 * from nfsroot parameter from being used. 51 * Olaf Kirch : Adapted to new NFS code. 52 * Jakub Jelinek : Free used code segment. 53 * Marko Kohtala : Fixed some bugs. 54 * Martin Mares : Debug message cleanup 55 * Martin Mares : Changed to use the new generic IP layer autoconfig 56 * code. BOOTP and RARP moved there. 57 * Martin Mares : Default path now contains host name instead of 58 * host IP address (but host name defaults to IP 59 * address anyway). 60 * Martin Mares : Use root_server_addr appropriately during setup. 61 * Martin Mares : Rewrote parameter parsing, now hopefully giving 62 * correct overriding. 63 * Trond Myklebust : Add in preliminary support for NFSv3 and TCP. 64 * Fix bug in root_nfs_addr(). nfs_data.namlen 65 * is NOT for the length of the hostname. 66 * Hua Qin : Support for mounting root file system via 67 * NFS over TCP. 68 * Fabian Frederick: Option parser rebuilt (using parser lib) 69 * Chuck Lever : Use super.c's text-based mount option parsing 70 * Chuck Lever : Add "nfsrootdebug". 71 */ 72 73 #include <linux/types.h> 74 #include <linux/string.h> 75 #include <linux/init.h> 76 #include <linux/nfs.h> 77 #include <linux/nfs_fs.h> 78 #include <linux/utsname.h> 79 #include <linux/root_dev.h> 80 #include <net/ipconfig.h> 81 82 #include "internal.h" 83 84 #define NFSDBG_FACILITY NFSDBG_ROOT 85 86 /* Default path we try to mount. "%s" gets replaced by our IP address */ 87 #define NFS_ROOT "/tftpboot/%s" 88 89 /* Default NFSROOT mount options. */ 90 #define NFS_DEF_OPTIONS "vers=2,udp,rsize=4096,wsize=4096" 91 92 /* Parameters passed from the kernel command line */ 93 static char nfs_root_parms[256] __initdata = ""; 94 95 /* Text-based mount options passed to super.c */ 96 static char nfs_root_options[256] __initdata = NFS_DEF_OPTIONS; 97 98 /* Address of NFS server */ 99 static __be32 servaddr __initdata = htonl(INADDR_NONE); 100 101 /* Name of directory to mount */ 102 static char nfs_export_path[NFS_MAXPATHLEN + 1] __initdata = ""; 103 104 /* server:export path string passed to super.c */ 105 static char nfs_root_device[NFS_MAXPATHLEN + 1] __initdata = ""; 106 107 #ifdef NFS_DEBUG 108 /* 109 * When the "nfsrootdebug" kernel command line option is specified, 110 * enable debugging messages for NFSROOT. 111 */ 112 static int __init nfs_root_debug(char *__unused) 113 { 114 nfs_debug |= NFSDBG_ROOT | NFSDBG_MOUNT; 115 return 1; 116 } 117 118 __setup("nfsrootdebug", nfs_root_debug); 119 #endif 120 121 /* 122 * Parse NFS server and directory information passed on the kernel 123 * command line. 124 * 125 * nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>] 126 * 127 * If there is a "%s" token in the <root-dir> string, it is replaced 128 * by the ASCII-representation of the client's IP address. 129 */ 130 static int __init nfs_root_setup(char *line) 131 { 132 ROOT_DEV = Root_NFS; 133 134 if (line[0] == '/' || line[0] == ',' || (line[0] >= '0' && line[0] <= '9')) { 135 strlcpy(nfs_root_parms, line, sizeof(nfs_root_parms)); 136 } else { 137 size_t n = strlen(line) + sizeof(NFS_ROOT) - 1; 138 if (n >= sizeof(nfs_root_parms)) 139 line[sizeof(nfs_root_parms) - sizeof(NFS_ROOT) - 2] = '\0'; 140 sprintf(nfs_root_parms, NFS_ROOT, line); 141 } 142 143 /* 144 * Extract the IP address of the NFS server containing our 145 * root file system, if one was specified. 146 * 147 * Note: root_nfs_parse_addr() removes the server-ip from 148 * nfs_root_parms, if it exists. 149 */ 150 root_server_addr = root_nfs_parse_addr(nfs_root_parms); 151 152 return 1; 153 } 154 155 __setup("nfsroot=", nfs_root_setup); 156 157 static int __init root_nfs_copy(char *dest, const char *src, 158 const size_t destlen) 159 { 160 if (strlcpy(dest, src, destlen) > destlen) 161 return -1; 162 return 0; 163 } 164 165 static int __init root_nfs_cat(char *dest, const char *src, 166 const size_t destlen) 167 { 168 size_t len = strlen(dest); 169 170 if (len && dest[len - 1] != ',') 171 if (strlcat(dest, ",", destlen) > destlen) 172 return -1; 173 174 if (strlcat(dest, src, destlen) > destlen) 175 return -1; 176 return 0; 177 } 178 179 /* 180 * Parse out root export path and mount options from 181 * passed-in string @incoming. 182 * 183 * Copy the export path into @exppath. 184 */ 185 static int __init root_nfs_parse_options(char *incoming, char *exppath, 186 const size_t exppathlen) 187 { 188 char *p; 189 190 /* 191 * Set the NFS remote path 192 */ 193 p = strsep(&incoming, ","); 194 if (*p != '\0' && strcmp(p, "default") != 0) 195 if (root_nfs_copy(exppath, p, exppathlen)) 196 return -1; 197 198 /* 199 * @incoming now points to the rest of the string; if it 200 * contains something, append it to our root options buffer 201 */ 202 if (incoming != NULL && *incoming != '\0') 203 if (root_nfs_cat(nfs_root_options, incoming, 204 sizeof(nfs_root_options))) 205 return -1; 206 return 0; 207 } 208 209 /* 210 * Decode the export directory path name and NFS options from 211 * the kernel command line. This has to be done late in order to 212 * use a dynamically acquired client IP address for the remote 213 * root directory path. 214 * 215 * Returns zero if successful; otherwise -1 is returned. 216 */ 217 static int __init root_nfs_data(char *cmdline) 218 { 219 char mand_options[sizeof("nolock,addr=") + INET_ADDRSTRLEN + 1]; 220 int len, retval = -1; 221 char *tmp = NULL; 222 const size_t tmplen = sizeof(nfs_export_path); 223 224 tmp = kzalloc(tmplen, GFP_KERNEL); 225 if (tmp == NULL) 226 goto out_nomem; 227 strcpy(tmp, NFS_ROOT); 228 229 if (root_server_path[0] != '\0') { 230 dprintk("Root-NFS: DHCPv4 option 17: %s\n", 231 root_server_path); 232 if (root_nfs_parse_options(root_server_path, tmp, tmplen)) 233 goto out_optionstoolong; 234 } 235 236 if (cmdline[0] != '\0') { 237 dprintk("Root-NFS: nfsroot=%s\n", cmdline); 238 if (root_nfs_parse_options(cmdline, tmp, tmplen)) 239 goto out_optionstoolong; 240 } 241 242 /* 243 * Append mandatory options for nfsroot so they override 244 * what has come before 245 */ 246 snprintf(mand_options, sizeof(mand_options), "nolock,addr=%pI4", 247 &servaddr); 248 if (root_nfs_cat(nfs_root_options, mand_options, 249 sizeof(nfs_root_options))) 250 goto out_optionstoolong; 251 252 /* 253 * Set up nfs_root_device. For NFS mounts, this looks like 254 * 255 * server:/path 256 * 257 * At this point, utsname()->nodename contains our local 258 * IP address or hostname, set by ipconfig. If "%s" exists 259 * in tmp, substitute the nodename, then shovel the whole 260 * mess into nfs_root_device. 261 */ 262 len = snprintf(nfs_export_path, sizeof(nfs_export_path), 263 tmp, utsname()->nodename); 264 if (len > (int)sizeof(nfs_export_path)) 265 goto out_devnametoolong; 266 len = snprintf(nfs_root_device, sizeof(nfs_root_device), 267 "%pI4:%s", &servaddr, nfs_export_path); 268 if (len > (int)sizeof(nfs_root_device)) 269 goto out_devnametoolong; 270 271 retval = 0; 272 273 out: 274 kfree(tmp); 275 return retval; 276 out_nomem: 277 printk(KERN_ERR "Root-NFS: could not allocate memory\n"); 278 goto out; 279 out_optionstoolong: 280 printk(KERN_ERR "Root-NFS: mount options string too long\n"); 281 goto out; 282 out_devnametoolong: 283 printk(KERN_ERR "Root-NFS: root device name too long.\n"); 284 goto out; 285 } 286 287 /** 288 * nfs_root_data - Return prepared 'data' for NFSROOT mount 289 * @root_device: OUT: address of string containing NFSROOT device 290 * @root_data: OUT: address of string containing NFSROOT mount options 291 * 292 * Returns zero and sets @root_device and @root_data if successful, 293 * otherwise -1 is returned. 294 */ 295 int __init nfs_root_data(char **root_device, char **root_data) 296 { 297 servaddr = root_server_addr; 298 if (servaddr == htonl(INADDR_NONE)) { 299 printk(KERN_ERR "Root-NFS: no NFS server address\n"); 300 return -1; 301 } 302 303 if (root_nfs_data(nfs_root_parms) < 0) 304 return -1; 305 306 *root_device = nfs_root_device; 307 *root_data = nfs_root_options; 308 return 0; 309 } 310