xref: /linux/init/initramfs.c (revision 14b42963f64b98ab61fa9723c03d71aa5ef4f862)
1 #include <linux/init.h>
2 #include <linux/fs.h>
3 #include <linux/slab.h>
4 #include <linux/types.h>
5 #include <linux/fcntl.h>
6 #include <linux/delay.h>
7 #include <linux/string.h>
8 #include <linux/syscalls.h>
9 
10 static __initdata char *message;
11 static void __init error(char *x)
12 {
13 	if (!message)
14 		message = x;
15 }
16 
17 static void __init *malloc(size_t size)
18 {
19 	return kmalloc(size, GFP_KERNEL);
20 }
21 
22 static void __init free(void *where)
23 {
24 	kfree(where);
25 }
26 
27 /* link hash */
28 
29 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
30 
31 static __initdata struct hash {
32 	int ino, minor, major;
33 	mode_t mode;
34 	struct hash *next;
35 	char name[N_ALIGN(PATH_MAX)];
36 } *head[32];
37 
38 static inline int hash(int major, int minor, int ino)
39 {
40 	unsigned long tmp = ino + minor + (major << 3);
41 	tmp += tmp >> 5;
42 	return tmp & 31;
43 }
44 
45 static char __init *find_link(int major, int minor, int ino,
46 			      mode_t mode, char *name)
47 {
48 	struct hash **p, *q;
49 	for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
50 		if ((*p)->ino != ino)
51 			continue;
52 		if ((*p)->minor != minor)
53 			continue;
54 		if ((*p)->major != major)
55 			continue;
56 		if (((*p)->mode ^ mode) & S_IFMT)
57 			continue;
58 		return (*p)->name;
59 	}
60 	q = (struct hash *)malloc(sizeof(struct hash));
61 	if (!q)
62 		panic("can't allocate link hash entry");
63 	q->major = major;
64 	q->minor = minor;
65 	q->ino = ino;
66 	q->mode = mode;
67 	strcpy(q->name, name);
68 	q->next = NULL;
69 	*p = q;
70 	return NULL;
71 }
72 
73 static void __init free_hash(void)
74 {
75 	struct hash **p, *q;
76 	for (p = head; p < head + 32; p++) {
77 		while (*p) {
78 			q = *p;
79 			*p = q->next;
80 			free(q);
81 		}
82 	}
83 }
84 
85 /* cpio header parsing */
86 
87 static __initdata unsigned long ino, major, minor, nlink;
88 static __initdata mode_t mode;
89 static __initdata unsigned long body_len, name_len;
90 static __initdata uid_t uid;
91 static __initdata gid_t gid;
92 static __initdata unsigned rdev;
93 
94 static void __init parse_header(char *s)
95 {
96 	unsigned long parsed[12];
97 	char buf[9];
98 	int i;
99 
100 	buf[8] = '\0';
101 	for (i = 0, s += 6; i < 12; i++, s += 8) {
102 		memcpy(buf, s, 8);
103 		parsed[i] = simple_strtoul(buf, NULL, 16);
104 	}
105 	ino = parsed[0];
106 	mode = parsed[1];
107 	uid = parsed[2];
108 	gid = parsed[3];
109 	nlink = parsed[4];
110 	body_len = parsed[6];
111 	major = parsed[7];
112 	minor = parsed[8];
113 	rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
114 	name_len = parsed[11];
115 }
116 
117 /* FSM */
118 
119 static __initdata enum state {
120 	Start,
121 	Collect,
122 	GotHeader,
123 	SkipIt,
124 	GotName,
125 	CopyFile,
126 	GotSymlink,
127 	Reset
128 } state, next_state;
129 
130 static __initdata char *victim;
131 static __initdata unsigned count;
132 static __initdata loff_t this_header, next_header;
133 
134 static __initdata int dry_run;
135 
136 static inline void eat(unsigned n)
137 {
138 	victim += n;
139 	this_header += n;
140 	count -= n;
141 }
142 
143 static __initdata char *collected;
144 static __initdata int remains;
145 static __initdata char *collect;
146 
147 static void __init read_into(char *buf, unsigned size, enum state next)
148 {
149 	if (count >= size) {
150 		collected = victim;
151 		eat(size);
152 		state = next;
153 	} else {
154 		collect = collected = buf;
155 		remains = size;
156 		next_state = next;
157 		state = Collect;
158 	}
159 }
160 
161 static __initdata char *header_buf, *symlink_buf, *name_buf;
162 
163 static int __init do_start(void)
164 {
165 	read_into(header_buf, 110, GotHeader);
166 	return 0;
167 }
168 
169 static int __init do_collect(void)
170 {
171 	unsigned n = remains;
172 	if (count < n)
173 		n = count;
174 	memcpy(collect, victim, n);
175 	eat(n);
176 	collect += n;
177 	if ((remains -= n) != 0)
178 		return 1;
179 	state = next_state;
180 	return 0;
181 }
182 
183 static int __init do_header(void)
184 {
185 	if (memcmp(collected, "070701", 6)) {
186 		error("no cpio magic");
187 		return 1;
188 	}
189 	parse_header(collected);
190 	next_header = this_header + N_ALIGN(name_len) + body_len;
191 	next_header = (next_header + 3) & ~3;
192 	if (dry_run) {
193 		read_into(name_buf, N_ALIGN(name_len), GotName);
194 		return 0;
195 	}
196 	state = SkipIt;
197 	if (name_len <= 0 || name_len > PATH_MAX)
198 		return 0;
199 	if (S_ISLNK(mode)) {
200 		if (body_len > PATH_MAX)
201 			return 0;
202 		collect = collected = symlink_buf;
203 		remains = N_ALIGN(name_len) + body_len;
204 		next_state = GotSymlink;
205 		state = Collect;
206 		return 0;
207 	}
208 	if (S_ISREG(mode) || !body_len)
209 		read_into(name_buf, N_ALIGN(name_len), GotName);
210 	return 0;
211 }
212 
213 static int __init do_skip(void)
214 {
215 	if (this_header + count < next_header) {
216 		eat(count);
217 		return 1;
218 	} else {
219 		eat(next_header - this_header);
220 		state = next_state;
221 		return 0;
222 	}
223 }
224 
225 static int __init do_reset(void)
226 {
227 	while(count && *victim == '\0')
228 		eat(1);
229 	if (count && (this_header & 3))
230 		error("broken padding");
231 	return 1;
232 }
233 
234 static int __init maybe_link(void)
235 {
236 	if (nlink >= 2) {
237 		char *old = find_link(major, minor, ino, mode, collected);
238 		if (old)
239 			return (sys_link(old, collected) < 0) ? -1 : 1;
240 	}
241 	return 0;
242 }
243 
244 static void __init clean_path(char *path, mode_t mode)
245 {
246 	struct stat st;
247 
248 	if (!sys_newlstat(path, &st) && (st.st_mode^mode) & S_IFMT) {
249 		if (S_ISDIR(st.st_mode))
250 			sys_rmdir(path);
251 		else
252 			sys_unlink(path);
253 	}
254 }
255 
256 static __initdata int wfd;
257 
258 static int __init do_name(void)
259 {
260 	state = SkipIt;
261 	next_state = Reset;
262 	if (strcmp(collected, "TRAILER!!!") == 0) {
263 		free_hash();
264 		return 0;
265 	}
266 	if (dry_run)
267 		return 0;
268 	clean_path(collected, mode);
269 	if (S_ISREG(mode)) {
270 		int ml = maybe_link();
271 		if (ml >= 0) {
272 			int openflags = O_WRONLY|O_CREAT;
273 			if (ml != 1)
274 				openflags |= O_TRUNC;
275 			wfd = sys_open(collected, openflags, mode);
276 
277 			if (wfd >= 0) {
278 				sys_fchown(wfd, uid, gid);
279 				sys_fchmod(wfd, mode);
280 				state = CopyFile;
281 			}
282 		}
283 	} else if (S_ISDIR(mode)) {
284 		sys_mkdir(collected, mode);
285 		sys_chown(collected, uid, gid);
286 		sys_chmod(collected, mode);
287 	} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
288 		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
289 		if (maybe_link() == 0) {
290 			sys_mknod(collected, mode, rdev);
291 			sys_chown(collected, uid, gid);
292 			sys_chmod(collected, mode);
293 		}
294 	}
295 	return 0;
296 }
297 
298 static int __init do_copy(void)
299 {
300 	if (count >= body_len) {
301 		sys_write(wfd, victim, body_len);
302 		sys_close(wfd);
303 		eat(body_len);
304 		state = SkipIt;
305 		return 0;
306 	} else {
307 		sys_write(wfd, victim, count);
308 		body_len -= count;
309 		eat(count);
310 		return 1;
311 	}
312 }
313 
314 static int __init do_symlink(void)
315 {
316 	collected[N_ALIGN(name_len) + body_len] = '\0';
317 	clean_path(collected, 0);
318 	sys_symlink(collected + N_ALIGN(name_len), collected);
319 	sys_lchown(collected, uid, gid);
320 	state = SkipIt;
321 	next_state = Reset;
322 	return 0;
323 }
324 
325 static __initdata int (*actions[])(void) = {
326 	[Start]		= do_start,
327 	[Collect]	= do_collect,
328 	[GotHeader]	= do_header,
329 	[SkipIt]	= do_skip,
330 	[GotName]	= do_name,
331 	[CopyFile]	= do_copy,
332 	[GotSymlink]	= do_symlink,
333 	[Reset]		= do_reset,
334 };
335 
336 static int __init write_buffer(char *buf, unsigned len)
337 {
338 	count = len;
339 	victim = buf;
340 
341 	while (!actions[state]())
342 		;
343 	return len - count;
344 }
345 
346 static void __init flush_buffer(char *buf, unsigned len)
347 {
348 	int written;
349 	if (message)
350 		return;
351 	while ((written = write_buffer(buf, len)) < len && !message) {
352 		char c = buf[written];
353 		if (c == '0') {
354 			buf += written;
355 			len -= written;
356 			state = Start;
357 		} else if (c == 0) {
358 			buf += written;
359 			len -= written;
360 			state = Reset;
361 		} else
362 			error("junk in compressed archive");
363 	}
364 }
365 
366 /*
367  * gzip declarations
368  */
369 
370 #define OF(args)  args
371 
372 #ifndef memzero
373 #define memzero(s, n)     memset ((s), 0, (n))
374 #endif
375 
376 typedef unsigned char  uch;
377 typedef unsigned short ush;
378 typedef unsigned long  ulg;
379 
380 #define WSIZE 0x8000    /* window size--must be a power of two, and */
381 			/*  at least 32K for zip's deflate method */
382 
383 static uch *inbuf;
384 static uch *window;
385 
386 static unsigned insize;  /* valid bytes in inbuf */
387 static unsigned inptr;   /* index of next byte to be processed in inbuf */
388 static unsigned outcnt;  /* bytes in output buffer */
389 static long bytes_out;
390 
391 #define get_byte()  (inptr < insize ? inbuf[inptr++] : -1)
392 
393 /* Diagnostic functions (stubbed out) */
394 #define Assert(cond,msg)
395 #define Trace(x)
396 #define Tracev(x)
397 #define Tracevv(x)
398 #define Tracec(c,x)
399 #define Tracecv(c,x)
400 
401 #define STATIC static
402 #define INIT __init
403 
404 static void __init flush_window(void);
405 static void __init error(char *m);
406 static void __init gzip_mark(void **);
407 static void __init gzip_release(void **);
408 
409 #include "../lib/inflate.c"
410 
411 static void __init gzip_mark(void **ptr)
412 {
413 }
414 
415 static void __init gzip_release(void **ptr)
416 {
417 }
418 
419 /* ===========================================================================
420  * Write the output window window[0..outcnt-1] and update crc and bytes_out.
421  * (Used for the decompressed data only.)
422  */
423 static void __init flush_window(void)
424 {
425 	ulg c = crc;         /* temporary variable */
426 	unsigned n;
427 	uch *in, ch;
428 
429 	flush_buffer(window, outcnt);
430 	in = window;
431 	for (n = 0; n < outcnt; n++) {
432 		ch = *in++;
433 		c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
434 	}
435 	crc = c;
436 	bytes_out += (ulg)outcnt;
437 	outcnt = 0;
438 }
439 
440 static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
441 {
442 	int written;
443 	dry_run = check_only;
444 	header_buf = malloc(110);
445 	symlink_buf = malloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1);
446 	name_buf = malloc(N_ALIGN(PATH_MAX));
447 	window = malloc(WSIZE);
448 	if (!window || !header_buf || !symlink_buf || !name_buf)
449 		panic("can't allocate buffers");
450 	state = Start;
451 	this_header = 0;
452 	message = NULL;
453 	while (!message && len) {
454 		loff_t saved_offset = this_header;
455 		if (*buf == '0' && !(this_header & 3)) {
456 			state = Start;
457 			written = write_buffer(buf, len);
458 			buf += written;
459 			len -= written;
460 			continue;
461 		}
462 		if (!*buf) {
463 			buf++;
464 			len--;
465 			this_header++;
466 			continue;
467 		}
468 		this_header = 0;
469 		insize = len;
470 		inbuf = buf;
471 		inptr = 0;
472 		outcnt = 0;		/* bytes in output buffer */
473 		bytes_out = 0;
474 		crc = (ulg)0xffffffffL; /* shift register contents */
475 		makecrc();
476 		gunzip();
477 		if (state != Reset)
478 			error("junk in gzipped archive");
479 		this_header = saved_offset + inptr;
480 		buf += inptr;
481 		len -= inptr;
482 	}
483 	free(window);
484 	free(name_buf);
485 	free(symlink_buf);
486 	free(header_buf);
487 	return message;
488 }
489 
490 extern char __initramfs_start[], __initramfs_end[];
491 #ifdef CONFIG_BLK_DEV_INITRD
492 #include <linux/initrd.h>
493 #include <linux/kexec.h>
494 
495 static void __init free_initrd(void)
496 {
497 #ifdef CONFIG_KEXEC
498 	unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
499 	unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
500 
501 	/*
502 	 * If the initrd region is overlapped with crashkernel reserved region,
503 	 * free only memory that is not part of crashkernel region.
504 	 */
505 	if (initrd_start < crashk_end && initrd_end > crashk_start) {
506 		/*
507 		 * Initialize initrd memory region since the kexec boot does
508 		 * not do.
509 		 */
510 		memset((void *)initrd_start, 0, initrd_end - initrd_start);
511 		if (initrd_start < crashk_start)
512 			free_initrd_mem(initrd_start, crashk_start);
513 		if (initrd_end > crashk_end)
514 			free_initrd_mem(crashk_end, initrd_end);
515 	} else
516 #endif
517 		free_initrd_mem(initrd_start, initrd_end);
518 
519 	initrd_start = 0;
520 	initrd_end = 0;
521 }
522 
523 #endif
524 
525 void __init populate_rootfs(void)
526 {
527 	char *err = unpack_to_rootfs(__initramfs_start,
528 			 __initramfs_end - __initramfs_start, 0);
529 	if (err)
530 		panic(err);
531 #ifdef CONFIG_BLK_DEV_INITRD
532 	if (initrd_start) {
533 #ifdef CONFIG_BLK_DEV_RAM
534 		int fd;
535 		printk(KERN_INFO "checking if image is initramfs...");
536 		err = unpack_to_rootfs((char *)initrd_start,
537 			initrd_end - initrd_start, 1);
538 		if (!err) {
539 			printk(" it is\n");
540 			unpack_to_rootfs((char *)initrd_start,
541 				initrd_end - initrd_start, 0);
542 			free_initrd();
543 			return;
544 		}
545 		printk("it isn't (%s); looks like an initrd\n", err);
546 		fd = sys_open("/initrd.image", O_WRONLY|O_CREAT, 0700);
547 		if (fd >= 0) {
548 			sys_write(fd, (char *)initrd_start,
549 					initrd_end - initrd_start);
550 			sys_close(fd);
551 			free_initrd();
552 		}
553 #else
554 		printk(KERN_INFO "Unpacking initramfs...");
555 		err = unpack_to_rootfs((char *)initrd_start,
556 			initrd_end - initrd_start, 0);
557 		if (err)
558 			panic(err);
559 		printk(" done\n");
560 		free_initrd();
561 #endif
562 	}
563 #endif
564 }
565