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TOMOYO Linux Cross Reference
Linux/init/initramfs.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 #include <linux/init.h>
  3 #include <linux/fs.h>
  4 #include <linux/slab.h>
  5 #include <linux/types.h>
  6 #include <linux/fcntl.h>
  7 #include <linux/delay.h>
  8 #include <linux/string.h>
  9 #include <linux/dirent.h>
 10 #include <linux/syscalls.h>
 11 #include <linux/utime.h>
 12 #include <linux/file.h>
 13 
 14 static ssize_t __init xwrite(int fd, const char *p, size_t count)
 15 {
 16         ssize_t out = 0;
 17 
 18         /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
 19         while (count) {
 20                 ssize_t rv = ksys_write(fd, p, count);
 21 
 22                 if (rv < 0) {
 23                         if (rv == -EINTR || rv == -EAGAIN)
 24                                 continue;
 25                         return out ? out : rv;
 26                 } else if (rv == 0)
 27                         break;
 28 
 29                 p += rv;
 30                 out += rv;
 31                 count -= rv;
 32         }
 33 
 34         return out;
 35 }
 36 
 37 static __initdata char *message;
 38 static void __init error(char *x)
 39 {
 40         if (!message)
 41                 message = x;
 42 }
 43 
 44 /* link hash */
 45 
 46 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
 47 
 48 static __initdata struct hash {
 49         int ino, minor, major;
 50         umode_t mode;
 51         struct hash *next;
 52         char name[N_ALIGN(PATH_MAX)];
 53 } *head[32];
 54 
 55 static inline int hash(int major, int minor, int ino)
 56 {
 57         unsigned long tmp = ino + minor + (major << 3);
 58         tmp += tmp >> 5;
 59         return tmp & 31;
 60 }
 61 
 62 static char __init *find_link(int major, int minor, int ino,
 63                               umode_t mode, char *name)
 64 {
 65         struct hash **p, *q;
 66         for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
 67                 if ((*p)->ino != ino)
 68                         continue;
 69                 if ((*p)->minor != minor)
 70                         continue;
 71                 if ((*p)->major != major)
 72                         continue;
 73                 if (((*p)->mode ^ mode) & S_IFMT)
 74                         continue;
 75                 return (*p)->name;
 76         }
 77         q = kmalloc(sizeof(struct hash), GFP_KERNEL);
 78         if (!q)
 79                 panic("can't allocate link hash entry");
 80         q->major = major;
 81         q->minor = minor;
 82         q->ino = ino;
 83         q->mode = mode;
 84         strcpy(q->name, name);
 85         q->next = NULL;
 86         *p = q;
 87         return NULL;
 88 }
 89 
 90 static void __init free_hash(void)
 91 {
 92         struct hash **p, *q;
 93         for (p = head; p < head + 32; p++) {
 94                 while (*p) {
 95                         q = *p;
 96                         *p = q->next;
 97                         kfree(q);
 98                 }
 99         }
100 }
101 
102 static long __init do_utime(char *filename, time64_t mtime)
103 {
104         struct timespec64 t[2];
105 
106         t[0].tv_sec = mtime;
107         t[0].tv_nsec = 0;
108         t[1].tv_sec = mtime;
109         t[1].tv_nsec = 0;
110 
111         return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW);
112 }
113 
114 static __initdata LIST_HEAD(dir_list);
115 struct dir_entry {
116         struct list_head list;
117         char *name;
118         time64_t mtime;
119 };
120 
121 static void __init dir_add(const char *name, time64_t mtime)
122 {
123         struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
124         if (!de)
125                 panic("can't allocate dir_entry buffer");
126         INIT_LIST_HEAD(&de->list);
127         de->name = kstrdup(name, GFP_KERNEL);
128         de->mtime = mtime;
129         list_add(&de->list, &dir_list);
130 }
131 
132 static void __init dir_utime(void)
133 {
134         struct dir_entry *de, *tmp;
135         list_for_each_entry_safe(de, tmp, &dir_list, list) {
136                 list_del(&de->list);
137                 do_utime(de->name, de->mtime);
138                 kfree(de->name);
139                 kfree(de);
140         }
141 }
142 
143 static __initdata time64_t mtime;
144 
145 /* cpio header parsing */
146 
147 static __initdata unsigned long ino, major, minor, nlink;
148 static __initdata umode_t mode;
149 static __initdata unsigned long body_len, name_len;
150 static __initdata uid_t uid;
151 static __initdata gid_t gid;
152 static __initdata unsigned rdev;
153 
154 static void __init parse_header(char *s)
155 {
156         unsigned long parsed[12];
157         char buf[9];
158         int i;
159 
160         buf[8] = '\0';
161         for (i = 0, s += 6; i < 12; i++, s += 8) {
162                 memcpy(buf, s, 8);
163                 parsed[i] = simple_strtoul(buf, NULL, 16);
164         }
165         ino = parsed[0];
166         mode = parsed[1];
167         uid = parsed[2];
168         gid = parsed[3];
169         nlink = parsed[4];
170         mtime = parsed[5]; /* breaks in y2106 */
171         body_len = parsed[6];
172         major = parsed[7];
173         minor = parsed[8];
174         rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
175         name_len = parsed[11];
176 }
177 
178 /* FSM */
179 
180 static __initdata enum state {
181         Start,
182         Collect,
183         GotHeader,
184         SkipIt,
185         GotName,
186         CopyFile,
187         GotSymlink,
188         Reset
189 } state, next_state;
190 
191 static __initdata char *victim;
192 static unsigned long byte_count __initdata;
193 static __initdata loff_t this_header, next_header;
194 
195 static inline void __init eat(unsigned n)
196 {
197         victim += n;
198         this_header += n;
199         byte_count -= n;
200 }
201 
202 static __initdata char *vcollected;
203 static __initdata char *collected;
204 static long remains __initdata;
205 static __initdata char *collect;
206 
207 static void __init read_into(char *buf, unsigned size, enum state next)
208 {
209         if (byte_count >= size) {
210                 collected = victim;
211                 eat(size);
212                 state = next;
213         } else {
214                 collect = collected = buf;
215                 remains = size;
216                 next_state = next;
217                 state = Collect;
218         }
219 }
220 
221 static __initdata char *header_buf, *symlink_buf, *name_buf;
222 
223 static int __init do_start(void)
224 {
225         read_into(header_buf, 110, GotHeader);
226         return 0;
227 }
228 
229 static int __init do_collect(void)
230 {
231         unsigned long n = remains;
232         if (byte_count < n)
233                 n = byte_count;
234         memcpy(collect, victim, n);
235         eat(n);
236         collect += n;
237         if ((remains -= n) != 0)
238                 return 1;
239         state = next_state;
240         return 0;
241 }
242 
243 static int __init do_header(void)
244 {
245         if (memcmp(collected, "070707", 6)==0) {
246                 error("incorrect cpio method used: use -H newc option");
247                 return 1;
248         }
249         if (memcmp(collected, "070701", 6)) {
250                 error("no cpio magic");
251                 return 1;
252         }
253         parse_header(collected);
254         next_header = this_header + N_ALIGN(name_len) + body_len;
255         next_header = (next_header + 3) & ~3;
256         state = SkipIt;
257         if (name_len <= 0 || name_len > PATH_MAX)
258                 return 0;
259         if (S_ISLNK(mode)) {
260                 if (body_len > PATH_MAX)
261                         return 0;
262                 collect = collected = symlink_buf;
263                 remains = N_ALIGN(name_len) + body_len;
264                 next_state = GotSymlink;
265                 state = Collect;
266                 return 0;
267         }
268         if (S_ISREG(mode) || !body_len)
269                 read_into(name_buf, N_ALIGN(name_len), GotName);
270         return 0;
271 }
272 
273 static int __init do_skip(void)
274 {
275         if (this_header + byte_count < next_header) {
276                 eat(byte_count);
277                 return 1;
278         } else {
279                 eat(next_header - this_header);
280                 state = next_state;
281                 return 0;
282         }
283 }
284 
285 static int __init do_reset(void)
286 {
287         while (byte_count && *victim == '\0')
288                 eat(1);
289         if (byte_count && (this_header & 3))
290                 error("broken padding");
291         return 1;
292 }
293 
294 static void __init clean_path(char *path, umode_t fmode)
295 {
296         struct kstat st;
297 
298         if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
299                 if (S_ISDIR(st.mode))
300                         ksys_rmdir(path);
301                 else
302                         ksys_unlink(path);
303         }
304 }
305 
306 static int __init maybe_link(void)
307 {
308         if (nlink >= 2) {
309                 char *old = find_link(major, minor, ino, mode, collected);
310                 if (old) {
311                         clean_path(collected, 0);
312                         return (ksys_link(old, collected) < 0) ? -1 : 1;
313                 }
314         }
315         return 0;
316 }
317 
318 static __initdata int wfd;
319 
320 static int __init do_name(void)
321 {
322         state = SkipIt;
323         next_state = Reset;
324         if (strcmp(collected, "TRAILER!!!") == 0) {
325                 free_hash();
326                 return 0;
327         }
328         clean_path(collected, mode);
329         if (S_ISREG(mode)) {
330                 int ml = maybe_link();
331                 if (ml >= 0) {
332                         int openflags = O_WRONLY|O_CREAT;
333                         if (ml != 1)
334                                 openflags |= O_TRUNC;
335                         wfd = ksys_open(collected, openflags, mode);
336 
337                         if (wfd >= 0) {
338                                 ksys_fchown(wfd, uid, gid);
339                                 ksys_fchmod(wfd, mode);
340                                 if (body_len)
341                                         ksys_ftruncate(wfd, body_len);
342                                 vcollected = kstrdup(collected, GFP_KERNEL);
343                                 state = CopyFile;
344                         }
345                 }
346         } else if (S_ISDIR(mode)) {
347                 ksys_mkdir(collected, mode);
348                 ksys_chown(collected, uid, gid);
349                 ksys_chmod(collected, mode);
350                 dir_add(collected, mtime);
351         } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
352                    S_ISFIFO(mode) || S_ISSOCK(mode)) {
353                 if (maybe_link() == 0) {
354                         ksys_mknod(collected, mode, rdev);
355                         ksys_chown(collected, uid, gid);
356                         ksys_chmod(collected, mode);
357                         do_utime(collected, mtime);
358                 }
359         }
360         return 0;
361 }
362 
363 static int __init do_copy(void)
364 {
365         if (byte_count >= body_len) {
366                 if (xwrite(wfd, victim, body_len) != body_len)
367                         error("write error");
368                 ksys_close(wfd);
369                 do_utime(vcollected, mtime);
370                 kfree(vcollected);
371                 eat(body_len);
372                 state = SkipIt;
373                 return 0;
374         } else {
375                 if (xwrite(wfd, victim, byte_count) != byte_count)
376                         error("write error");
377                 body_len -= byte_count;
378                 eat(byte_count);
379                 return 1;
380         }
381 }
382 
383 static int __init do_symlink(void)
384 {
385         collected[N_ALIGN(name_len) + body_len] = '\0';
386         clean_path(collected, 0);
387         ksys_symlink(collected + N_ALIGN(name_len), collected);
388         ksys_lchown(collected, uid, gid);
389         do_utime(collected, mtime);
390         state = SkipIt;
391         next_state = Reset;
392         return 0;
393 }
394 
395 static __initdata int (*actions[])(void) = {
396         [Start]         = do_start,
397         [Collect]       = do_collect,
398         [GotHeader]     = do_header,
399         [SkipIt]        = do_skip,
400         [GotName]       = do_name,
401         [CopyFile]      = do_copy,
402         [GotSymlink]    = do_symlink,
403         [Reset]         = do_reset,
404 };
405 
406 static long __init write_buffer(char *buf, unsigned long len)
407 {
408         byte_count = len;
409         victim = buf;
410 
411         while (!actions[state]())
412                 ;
413         return len - byte_count;
414 }
415 
416 static long __init flush_buffer(void *bufv, unsigned long len)
417 {
418         char *buf = (char *) bufv;
419         long written;
420         long origLen = len;
421         if (message)
422                 return -1;
423         while ((written = write_buffer(buf, len)) < len && !message) {
424                 char c = buf[written];
425                 if (c == '') {
426                         buf += written;
427                         len -= written;
428                         state = Start;
429                 } else if (c == 0) {
430                         buf += written;
431                         len -= written;
432                         state = Reset;
433                 } else
434                         error("junk within compressed archive");
435         }
436         return origLen;
437 }
438 
439 static unsigned long my_inptr; /* index of next byte to be processed in inbuf */
440 
441 #include <linux/decompress/generic.h>
442 
443 static char * __init unpack_to_rootfs(char *buf, unsigned long len)
444 {
445         long written;
446         decompress_fn decompress;
447         const char *compress_name;
448         static __initdata char msg_buf[64];
449 
450         header_buf = kmalloc(110, GFP_KERNEL);
451         symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
452         name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
453 
454         if (!header_buf || !symlink_buf || !name_buf)
455                 panic("can't allocate buffers");
456 
457         state = Start;
458         this_header = 0;
459         message = NULL;
460         while (!message && len) {
461                 loff_t saved_offset = this_header;
462                 if (*buf == '' && !(this_header & 3)) {
463                         state = Start;
464                         written = write_buffer(buf, len);
465                         buf += written;
466                         len -= written;
467                         continue;
468                 }
469                 if (!*buf) {
470                         buf++;
471                         len--;
472                         this_header++;
473                         continue;
474                 }
475                 this_header = 0;
476                 decompress = decompress_method(buf, len, &compress_name);
477                 pr_debug("Detected %s compressed data\n", compress_name);
478                 if (decompress) {
479                         int res = decompress(buf, len, NULL, flush_buffer, NULL,
480                                    &my_inptr, error);
481                         if (res)
482                                 error("decompressor failed");
483                 } else if (compress_name) {
484                         if (!message) {
485                                 snprintf(msg_buf, sizeof msg_buf,
486                                          "compression method %s not configured",
487                                          compress_name);
488                                 message = msg_buf;
489                         }
490                 } else
491                         error("invalid magic at start of compressed archive");
492                 if (state != Reset)
493                         error("junk at the end of compressed archive");
494                 this_header = saved_offset + my_inptr;
495                 buf += my_inptr;
496                 len -= my_inptr;
497         }
498         dir_utime();
499         kfree(name_buf);
500         kfree(symlink_buf);
501         kfree(header_buf);
502         return message;
503 }
504 
505 static int __initdata do_retain_initrd;
506 
507 static int __init retain_initrd_param(char *str)
508 {
509         if (*str)
510                 return 0;
511         do_retain_initrd = 1;
512         return 1;
513 }
514 __setup("retain_initrd", retain_initrd_param);
515 
516 extern char __initramfs_start[];
517 extern unsigned long __initramfs_size;
518 #include <linux/initrd.h>
519 #include <linux/kexec.h>
520 
521 static void __init free_initrd(void)
522 {
523 #ifdef CONFIG_KEXEC_CORE
524         unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
525         unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
526 #endif
527         if (do_retain_initrd)
528                 goto skip;
529 
530 #ifdef CONFIG_KEXEC_CORE
531         /*
532          * If the initrd region is overlapped with crashkernel reserved region,
533          * free only memory that is not part of crashkernel region.
534          */
535         if (initrd_start < crashk_end && initrd_end > crashk_start) {
536                 /*
537                  * Initialize initrd memory region since the kexec boot does
538                  * not do.
539                  */
540                 memset((void *)initrd_start, 0, initrd_end - initrd_start);
541                 if (initrd_start < crashk_start)
542                         free_initrd_mem(initrd_start, crashk_start);
543                 if (initrd_end > crashk_end)
544                         free_initrd_mem(crashk_end, initrd_end);
545         } else
546 #endif
547                 free_initrd_mem(initrd_start, initrd_end);
548 skip:
549         initrd_start = 0;
550         initrd_end = 0;
551 }
552 
553 #ifdef CONFIG_BLK_DEV_RAM
554 #define BUF_SIZE 1024
555 static void __init clean_rootfs(void)
556 {
557         int fd;
558         void *buf;
559         struct linux_dirent64 *dirp;
560         int num;
561 
562         fd = ksys_open("/", O_RDONLY, 0);
563         WARN_ON(fd < 0);
564         if (fd < 0)
565                 return;
566         buf = kzalloc(BUF_SIZE, GFP_KERNEL);
567         WARN_ON(!buf);
568         if (!buf) {
569                 ksys_close(fd);
570                 return;
571         }
572 
573         dirp = buf;
574         num = ksys_getdents64(fd, dirp, BUF_SIZE);
575         while (num > 0) {
576                 while (num > 0) {
577                         struct kstat st;
578                         int ret;
579 
580                         ret = vfs_lstat(dirp->d_name, &st);
581                         WARN_ON_ONCE(ret);
582                         if (!ret) {
583                                 if (S_ISDIR(st.mode))
584                                         ksys_rmdir(dirp->d_name);
585                                 else
586                                         ksys_unlink(dirp->d_name);
587                         }
588 
589                         num -= dirp->d_reclen;
590                         dirp = (void *)dirp + dirp->d_reclen;
591                 }
592                 dirp = buf;
593                 memset(buf, 0, BUF_SIZE);
594                 num = ksys_getdents64(fd, dirp, BUF_SIZE);
595         }
596 
597         ksys_close(fd);
598         kfree(buf);
599 }
600 #endif
601 
602 static int __init populate_rootfs(void)
603 {
604         /* Load the built in initramfs */
605         char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
606         if (err)
607                 panic("%s", err); /* Failed to decompress INTERNAL initramfs */
608         /* If available load the bootloader supplied initrd */
609         if (initrd_start && !IS_ENABLED(CONFIG_INITRAMFS_FORCE)) {
610 #ifdef CONFIG_BLK_DEV_RAM
611                 int fd;
612                 printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
613                 err = unpack_to_rootfs((char *)initrd_start,
614                         initrd_end - initrd_start);
615                 if (!err) {
616                         free_initrd();
617                         goto done;
618                 } else {
619                         clean_rootfs();
620                         unpack_to_rootfs(__initramfs_start, __initramfs_size);
621                 }
622                 printk(KERN_INFO "rootfs image is not initramfs (%s)"
623                                 "; looks like an initrd\n", err);
624                 fd = ksys_open("/initrd.image",
625                               O_WRONLY|O_CREAT, 0700);
626                 if (fd >= 0) {
627                         ssize_t written = xwrite(fd, (char *)initrd_start,
628                                                 initrd_end - initrd_start);
629 
630                         if (written != initrd_end - initrd_start)
631                                 pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
632                                        written, initrd_end - initrd_start);
633 
634                         ksys_close(fd);
635                         free_initrd();
636                 }
637         done:
638                 /* empty statement */;
639 #else
640                 printk(KERN_INFO "Unpacking initramfs...\n");
641                 err = unpack_to_rootfs((char *)initrd_start,
642                         initrd_end - initrd_start);
643                 if (err)
644                         printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
645                 free_initrd();
646 #endif
647         }
648         flush_delayed_fput();
649         return 0;
650 }
651 rootfs_initcall(populate_rootfs);
652 

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