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Linux/init/do_mounts_rd.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Many of the syscalls used in this file expect some of the arguments
  4  * to be __user pointers not __kernel pointers.  To limit the sparse
  5  * noise, turn off sparse checking for this file.
  6  */
  7 #ifdef __CHECKER__
  8 #undef __CHECKER__
  9 #warning "Sparse checking disabled for this file"
 10 #endif
 11 
 12 #include <linux/kernel.h>
 13 #include <linux/fs.h>
 14 #include <linux/minix_fs.h>
 15 #include <linux/ext2_fs.h>
 16 #include <linux/romfs_fs.h>
 17 #include <uapi/linux/cramfs_fs.h>
 18 #include <linux/initrd.h>
 19 #include <linux/string.h>
 20 #include <linux/slab.h>
 21 
 22 #include "do_mounts.h"
 23 #include "../fs/squashfs/squashfs_fs.h"
 24 
 25 #include <linux/decompress/generic.h>
 26 
 27 
 28 int __initdata rd_prompt = 1;/* 1 = prompt for RAM disk, 0 = don't prompt */
 29 
 30 static int __init prompt_ramdisk(char *str)
 31 {
 32         rd_prompt = simple_strtol(str,NULL,0) & 1;
 33         return 1;
 34 }
 35 __setup("prompt_ramdisk=", prompt_ramdisk);
 36 
 37 int __initdata rd_image_start;          /* starting block # of image */
 38 
 39 static int __init ramdisk_start_setup(char *str)
 40 {
 41         rd_image_start = simple_strtol(str,NULL,0);
 42         return 1;
 43 }
 44 __setup("ramdisk_start=", ramdisk_start_setup);
 45 
 46 static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);
 47 
 48 /*
 49  * This routine tries to find a RAM disk image to load, and returns the
 50  * number of blocks to read for a non-compressed image, 0 if the image
 51  * is a compressed image, and -1 if an image with the right magic
 52  * numbers could not be found.
 53  *
 54  * We currently check for the following magic numbers:
 55  *      minix
 56  *      ext2
 57  *      romfs
 58  *      cramfs
 59  *      squashfs
 60  *      gzip
 61  *      bzip2
 62  *      lzma
 63  *      xz
 64  *      lzo
 65  *      lz4
 66  */
 67 static int __init
 68 identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
 69 {
 70         const int size = 512;
 71         struct minix_super_block *minixsb;
 72         struct romfs_super_block *romfsb;
 73         struct cramfs_super *cramfsb;
 74         struct squashfs_super_block *squashfsb;
 75         int nblocks = -1;
 76         unsigned char *buf;
 77         const char *compress_name;
 78         unsigned long n;
 79 
 80         buf = kmalloc(size, GFP_KERNEL);
 81         if (!buf)
 82                 return -ENOMEM;
 83 
 84         minixsb = (struct minix_super_block *) buf;
 85         romfsb = (struct romfs_super_block *) buf;
 86         cramfsb = (struct cramfs_super *) buf;
 87         squashfsb = (struct squashfs_super_block *) buf;
 88         memset(buf, 0xe5, size);
 89 
 90         /*
 91          * Read block 0 to test for compressed kernel
 92          */
 93         sys_lseek(fd, start_block * BLOCK_SIZE, 0);
 94         sys_read(fd, buf, size);
 95 
 96         *decompressor = decompress_method(buf, size, &compress_name);
 97         if (compress_name) {
 98                 printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
 99                        compress_name, start_block);
100                 if (!*decompressor)
101                         printk(KERN_EMERG
102                                "RAMDISK: %s decompressor not configured!\n",
103                                compress_name);
104                 nblocks = 0;
105                 goto done;
106         }
107 
108         /* romfs is at block zero too */
109         if (romfsb->word0 == ROMSB_WORD0 &&
110             romfsb->word1 == ROMSB_WORD1) {
111                 printk(KERN_NOTICE
112                        "RAMDISK: romfs filesystem found at block %d\n",
113                        start_block);
114                 nblocks = (ntohl(romfsb->size)+BLOCK_SIZE-1)>>BLOCK_SIZE_BITS;
115                 goto done;
116         }
117 
118         if (cramfsb->magic == CRAMFS_MAGIC) {
119                 printk(KERN_NOTICE
120                        "RAMDISK: cramfs filesystem found at block %d\n",
121                        start_block);
122                 nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
123                 goto done;
124         }
125 
126         /* squashfs is at block zero too */
127         if (le32_to_cpu(squashfsb->s_magic) == SQUASHFS_MAGIC) {
128                 printk(KERN_NOTICE
129                        "RAMDISK: squashfs filesystem found at block %d\n",
130                        start_block);
131                 nblocks = (le64_to_cpu(squashfsb->bytes_used) + BLOCK_SIZE - 1)
132                          >> BLOCK_SIZE_BITS;
133                 goto done;
134         }
135 
136         /*
137          * Read 512 bytes further to check if cramfs is padded
138          */
139         sys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
140         sys_read(fd, buf, size);
141 
142         if (cramfsb->magic == CRAMFS_MAGIC) {
143                 printk(KERN_NOTICE
144                        "RAMDISK: cramfs filesystem found at block %d\n",
145                        start_block);
146                 nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
147                 goto done;
148         }
149 
150         /*
151          * Read block 1 to test for minix and ext2 superblock
152          */
153         sys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
154         sys_read(fd, buf, size);
155 
156         /* Try minix */
157         if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
158             minixsb->s_magic == MINIX_SUPER_MAGIC2) {
159                 printk(KERN_NOTICE
160                        "RAMDISK: Minix filesystem found at block %d\n",
161                        start_block);
162                 nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
163                 goto done;
164         }
165 
166         /* Try ext2 */
167         n = ext2_image_size(buf);
168         if (n) {
169                 printk(KERN_NOTICE
170                        "RAMDISK: ext2 filesystem found at block %d\n",
171                        start_block);
172                 nblocks = n;
173                 goto done;
174         }
175 
176         printk(KERN_NOTICE
177                "RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
178                start_block);
179 
180 done:
181         sys_lseek(fd, start_block * BLOCK_SIZE, 0);
182         kfree(buf);
183         return nblocks;
184 }
185 
186 int __init rd_load_image(char *from)
187 {
188         int res = 0;
189         int in_fd, out_fd;
190         unsigned long rd_blocks, devblocks;
191         int nblocks, i, disk;
192         char *buf = NULL;
193         unsigned short rotate = 0;
194         decompress_fn decompressor = NULL;
195 #if !defined(CONFIG_S390)
196         char rotator[4] = { '|' , '/' , '-' , '\\' };
197 #endif
198 
199         out_fd = sys_open("/dev/ram", O_RDWR, 0);
200         if (out_fd < 0)
201                 goto out;
202 
203         in_fd = sys_open(from, O_RDONLY, 0);
204         if (in_fd < 0)
205                 goto noclose_input;
206 
207         nblocks = identify_ramdisk_image(in_fd, rd_image_start, &decompressor);
208         if (nblocks < 0)
209                 goto done;
210 
211         if (nblocks == 0) {
212                 if (crd_load(in_fd, out_fd, decompressor) == 0)
213                         goto successful_load;
214                 goto done;
215         }
216 
217         /*
218          * NOTE NOTE: nblocks is not actually blocks but
219          * the number of kibibytes of data to load into a ramdisk.
220          */
221         if (sys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
222                 rd_blocks = 0;
223         else
224                 rd_blocks >>= 1;
225 
226         if (nblocks > rd_blocks) {
227                 printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
228                        nblocks, rd_blocks);
229                 goto done;
230         }
231 
232         /*
233          * OK, time to copy in the data
234          */
235         if (sys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
236                 devblocks = 0;
237         else
238                 devblocks >>= 1;
239 
240         if (strcmp(from, "/initrd.image") == 0)
241                 devblocks = nblocks;
242 
243         if (devblocks == 0) {
244                 printk(KERN_ERR "RAMDISK: could not determine device size\n");
245                 goto done;
246         }
247 
248         buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
249         if (!buf) {
250                 printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
251                 goto done;
252         }
253 
254         printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
255                 nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : "");
256         for (i = 0, disk = 1; i < nblocks; i++) {
257                 if (i && (i % devblocks == 0)) {
258                         printk("done disk #%d.\n", disk++);
259                         rotate = 0;
260                         if (sys_close(in_fd)) {
261                                 printk("Error closing the disk.\n");
262                                 goto noclose_input;
263                         }
264                         change_floppy("disk #%d", disk);
265                         in_fd = sys_open(from, O_RDONLY, 0);
266                         if (in_fd < 0)  {
267                                 printk("Error opening disk.\n");
268                                 goto noclose_input;
269                         }
270                         printk("Loading disk #%d... ", disk);
271                 }
272                 sys_read(in_fd, buf, BLOCK_SIZE);
273                 sys_write(out_fd, buf, BLOCK_SIZE);
274 #if !defined(CONFIG_S390)
275                 if (!(i % 16)) {
276                         pr_cont("%c\b", rotator[rotate & 0x3]);
277                         rotate++;
278                 }
279 #endif
280         }
281         printk("done.\n");
282 
283 successful_load:
284         res = 1;
285 done:
286         sys_close(in_fd);
287 noclose_input:
288         sys_close(out_fd);
289 out:
290         kfree(buf);
291         sys_unlink("/dev/ram");
292         return res;
293 }
294 
295 int __init rd_load_disk(int n)
296 {
297         if (rd_prompt)
298                 change_floppy("root floppy disk to be loaded into RAM disk");
299         create_dev("/dev/root", ROOT_DEV);
300         create_dev("/dev/ram", MKDEV(RAMDISK_MAJOR, n));
301         return rd_load_image("/dev/root");
302 }
303 
304 static int exit_code;
305 static int decompress_error;
306 static int crd_infd, crd_outfd;
307 
308 static long __init compr_fill(void *buf, unsigned long len)
309 {
310         long r = sys_read(crd_infd, buf, len);
311         if (r < 0)
312                 printk(KERN_ERR "RAMDISK: error while reading compressed data");
313         else if (r == 0)
314                 printk(KERN_ERR "RAMDISK: EOF while reading compressed data");
315         return r;
316 }
317 
318 static long __init compr_flush(void *window, unsigned long outcnt)
319 {
320         long written = sys_write(crd_outfd, window, outcnt);
321         if (written != outcnt) {
322                 if (decompress_error == 0)
323                         printk(KERN_ERR
324                                "RAMDISK: incomplete write (%ld != %ld)\n",
325                                written, outcnt);
326                 decompress_error = 1;
327                 return -1;
328         }
329         return outcnt;
330 }
331 
332 static void __init error(char *x)
333 {
334         printk(KERN_ERR "%s\n", x);
335         exit_code = 1;
336         decompress_error = 1;
337 }
338 
339 static int __init crd_load(int in_fd, int out_fd, decompress_fn deco)
340 {
341         int result;
342         crd_infd = in_fd;
343         crd_outfd = out_fd;
344 
345         if (!deco) {
346                 pr_emerg("Invalid ramdisk decompression routine.  "
347                          "Select appropriate config option.\n");
348                 panic("Could not decompress initial ramdisk image.");
349         }
350 
351         result = deco(NULL, 0, compr_fill, compr_flush, NULL, NULL, error);
352         if (decompress_error)
353                 result = 1;
354         return result;
355 }
356 

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