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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 RPC_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 |
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