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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * 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.
Chuck Lever56463e52010-09-17 10:54:37 -04006 * (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().
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 *
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
Jan Engelhardt96de0e22007-10-19 23:21:04 +020045 * Swen Thümmler : Allow to specify the NFS options in nfs_root
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 * 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)
Chuck Lever56463e52010-09-17 10:54:37 -040069 * Chuck Lever : Use super.c's text-based mount option parsing
Chuck Lever306a0752010-09-17 10:54:37 -040070 * Chuck Lever : Add "nfsrootdebug".
Chuck Lever56463e52010-09-17 10:54:37 -040071 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Linus Torvalds1da177e2005-04-16 15:20:36 -070073#include <linux/types.h>
74#include <linux/string.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070075#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070076#include <linux/nfs.h>
77#include <linux/nfs_fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070078#include <linux/utsname.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070079#include <linux/root_dev.h>
80#include <net/ipconfig.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070081
Chuck Lever146ec942008-12-23 15:21:34 -050082#include "internal.h"
83
Linus Torvalds1da177e2005-04-16 15:20:36 -070084#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
Chuck Lever53d47372011-03-11 15:31:06 -050089/* Default NFSROOT mount options. */
90#define NFS_DEF_OPTIONS "udp"
91
Linus Torvalds1da177e2005-04-16 15:20:36 -070092/* Parameters passed from the kernel command line */
Chuck Lever60ac0362010-09-17 10:54:37 -040093static char nfs_root_parms[256] __initdata = "";
Linus Torvalds1da177e2005-04-16 15:20:36 -070094
Chuck Lever56463e52010-09-17 10:54:37 -040095/* Text-based mount options passed to super.c */
Chuck Lever53d47372011-03-11 15:31:06 -050096static char nfs_root_options[256] __initdata = NFS_DEF_OPTIONS;
Chuck Lever56463e52010-09-17 10:54:37 -040097
Linus Torvalds1da177e2005-04-16 15:20:36 -070098/* Address of NFS server */
Chuck Lever8d232102010-09-17 10:54:37 -040099static __be32 servaddr __initdata = htonl(INADDR_NONE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
101/* Name of directory to mount */
Chuck Lever56463e52010-09-17 10:54:37 -0400102static char nfs_export_path[NFS_MAXPATHLEN + 1] __initdata = "";
103
104/* server:export path string passed to super.c */
105static char nfs_root_device[NFS_MAXPATHLEN + 1] __initdata = "";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
Trond Myklebust036a1072010-10-26 13:47:04 -0400107#ifdef RPC_DEBUG
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108/*
Chuck Lever306a0752010-09-17 10:54:37 -0400109 * When the "nfsrootdebug" kernel command line option is specified,
110 * enable debugging messages for NFSROOT.
111 */
112static 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);
Trond Myklebust036a1072010-10-26 13:47:04 -0400119#endif
Chuck Lever306a0752010-09-17 10:54:37 -0400120
121/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 * Parse NFS server and directory information passed on the kernel
123 * command line.
Chuck Lever60ac0362010-09-17 10:54:37 -0400124 *
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 */
130static int __init nfs_root_setup(char *line)
131{
132 ROOT_DEV = Root_NFS;
Chuck Lever60ac0362010-09-17 10:54:37 -0400133
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 if (line[0] == '/' || line[0] == ',' || (line[0] >= '0' && line[0] <= '9')) {
Chuck Lever60ac0362010-09-17 10:54:37 -0400135 strlcpy(nfs_root_parms, line, sizeof(nfs_root_parms));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 } else {
Chuck Lever60ac0362010-09-17 10:54:37 -0400137 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 }
Chuck Lever60ac0362010-09-17 10:54:37 -0400142
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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 return 1;
153}
154
155__setup("nfsroot=", nfs_root_setup);
156
Chuck Lever56463e52010-09-17 10:54:37 -0400157static 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
165static int __init root_nfs_cat(char *dest, const char *src,
Chuck Lever53d47372011-03-11 15:31:06 -0500166 const size_t destlen)
Chuck Lever56463e52010-09-17 10:54:37 -0400167{
Chuck Lever53d47372011-03-11 15:31:06 -0500168 size_t len = strlen(dest);
169
170 if (len && dest[len - 1] != ',')
171 if (strlcat(dest, ",", destlen) > destlen)
172 return -1;
173
Chuck Lever56463e52010-09-17 10:54:37 -0400174 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 */
185static 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;
Chuck Lever56463e52010-09-17 10:54:37 -0400206 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 */
217static int __init root_nfs_data(char *cmdline)
218{
Chuck Lever53d47372011-03-11 15:31:06 -0500219 char mand_options[sizeof("nolock,addr=") + INET_ADDRSTRLEN + 1];
Chuck Lever56463e52010-09-17 10:54:37 -0400220 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 */
Chuck Lever53d47372011-03-11 15:31:06 -0500246 snprintf(mand_options, sizeof(mand_options), "nolock,addr=%pI4",
Chuck Lever56463e52010-09-17 10:54:37 -0400247 &servaddr);
Chuck Lever53d47372011-03-11 15:31:06 -0500248 if (root_nfs_cat(nfs_root_options, mand_options,
Chuck Lever56463e52010-09-17 10:54:37 -0400249 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
273out:
274 kfree(tmp);
275 return retval;
276out_nomem:
277 printk(KERN_ERR "Root-NFS: could not allocate memory\n");
278 goto out;
279out_optionstoolong:
280 printk(KERN_ERR "Root-NFS: mount options string too long\n");
281 goto out;
282out_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 */
295int __init nfs_root_data(char **root_device, char **root_data)
296{
Chuck Lever56463e52010-09-17 10:54:37 -0400297 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}