cregit-Linux how code gets into the kernel

Release 4.15 lib/earlycpio.c

Directory: lib
/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2012 Intel Corporation; author H. Peter Anvin
 *
 *   This file is part of the Linux kernel, and is made available
 *   under the terms of the GNU General Public License version 2, as
 *   published by the Free Software Foundation.
 *
 *   This program is distributed in the hope it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *   General Public License for more details.
 *
 * ----------------------------------------------------------------------- */

/*
 * 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
};

/**
 * cpio_data 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 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); } strlcpy(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; }

Contributors

PersonTokensPropCommitsCommitProp
H. Peter Anvin40598.54%133.33%
Borislav Petkov40.97%133.33%
Tang Chen20.49%133.33%
Total411100.00%3100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
H. Peter Anvin45098.47%133.33%
Borislav Petkov40.88%133.33%
Tang Chen30.66%133.33%
Total457100.00%3100.00%
Directory: lib
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