// SPDX-License-Identifier: GPL-2.0-only/* ----------------------------------------------------------------------- * * *   Copyright 2012 Intel Corporation; author H. Peter Anvin * * ----------------------------------------------------------------------- */ /* * earlycpio.c * * Find a specific cpio member; must precede any compressed content. * This is used to locate data items in the initramfs used by the * kernel itself during early boot (before the main initramfs is * decompressed.)  It is the responsibility of the initramfs creator * to ensure that these items are uncompressed at the head of the * blob.  Depending on the boot loader or package tool that may be a * separate file or part of the same file. */ #include <linux/earlycpio.h>#include <linux/kernel.h>#include <linux/string.h> enum cpio_fields {	C_MAGIC,	C_INO,	C_MODE,	C_UID,	C_GID,	C_NLINK,	C_MTIME,	C_FILESIZE,	C_MAJ,	C_MIN,	C_RMAJ,	C_RMIN,	C_NAMESIZE,	C_CHKSUM,	C_NFIELDS}; /** * find_cpio_data - Search for files in an uncompressed cpio * @path:       The directory to search for, including a slash at the end * @data:       Pointer to the cpio archive or a header inside * @len:        Remaining length of the cpio based on data pointer * @nextoff:    When a matching file is found, this is the offset from the *              beginning of the cpio to the beginning of the next file, not the *              matching file itself. It can be used to iterate through the cpio *              to find all files inside of a directory path. * * Return:      &struct cpio_data containing the address, length and *              filename (with the directory path cut off) of the found file. *              If you search for a filename and not for files in a directory, *              pass the absolute path of the filename in the cpio and make sure *              the match returned an empty filename string. */ struct cpio_data find_cpio_data(const char *path, void *data,				size_t len,  long *nextoff){	const size_t cpio_header_len = 8*C_NFIELDS - 2;	struct cpio_data cd = { NULL, 0, "" };	const char *p, *dptr, *nptr;	unsigned int ch[C_NFIELDS], *chp, v;	unsigned char c, x;	size_t mypathsize = strlen(path);	int i, j; 	p = data; 	while (len > cpio_header_len) {		if (!*p) {			/* All cpio headers need to be 4-byte aligned */			p += 4;			len -= 4;			continue;		} 		j = 6;		/* The magic field is only 6 characters */		chp = ch;		for (i = C_NFIELDS; i; i--) {			v = 0;			while (j--) {				v <<= 4;				c = *p++; 				x = c - '0';				if (x < 10) {					v += x;					continue;				} 				x = (c | 0x20) - 'a';				if (x < 6) {					v += x + 10;					continue;				} 				goto quit; /* Invalid hexadecimal */			}			*chp++ = v;			j = 8;	/* All other fields are 8 characters */		} 		if ((ch[C_MAGIC] - 0x070701) > 1)			goto quit; /* Invalid magic */ 		len -= cpio_header_len; 		dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);		nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4); 		if (nptr > p + len || dptr < p || nptr < dptr)			goto quit; /* Buffer overrun */ 		if ((ch[C_MODE] & 0170000) == 0100000 &&		    ch[C_NAMESIZE] >= mypathsize &&		    !memcmp(p, path, mypathsize)) { 			if (nextoff)				*nextoff = (long)nptr - (long)data; 			if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {				pr_warn(				"File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",				p, MAX_CPIO_FILE_NAME);			}			strscpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME); 			cd.data = (void *)dptr;			cd.size = ch[C_FILESIZE];			return cd; /* Found it! */		}		len -= (nptr - p);		p = nptr;	} quit:	return cd;}