cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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namei.c (3098B)

      1// SPDX-License-Identifier: GPL-2.0
      2/* 
      3 * QNX4 file system, Linux implementation.
      4 * 
      5 * Version : 0.2.1
      6 * 
      7 * Using parts of the xiafs filesystem.
      8 * 
      9 * History :
     10 * 
     11 * 01-06-1998 by Richard Frowijn : first release.
     12 * 21-06-1998 by Frank Denis : dcache support, fixed error codes.
     13 * 04-07-1998 by Frank Denis : first step for rmdir/unlink.
     14 */
     15
     16#include <linux/buffer_head.h>
     17#include "qnx4.h"
     18
     19
     20/*
     21 * check if the filename is correct. For some obscure reason, qnx writes a
     22 * new file twice in the directory entry, first with all possible options at 0
     23 * and for a second time the way it is, they want us not to access the qnx
     24 * filesystem when whe are using linux.
     25 */
     26static int qnx4_match(int len, const char *name,
     27		      struct buffer_head *bh, unsigned long *offset)
     28{
     29	struct qnx4_inode_entry *de;
     30	int namelen, thislen;
     31
     32	if (bh == NULL) {
     33		printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
     34		return 0;
     35	}
     36	de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
     37	*offset += QNX4_DIR_ENTRY_SIZE;
     38	if ((de->di_status & QNX4_FILE_LINK) != 0) {
     39		namelen = QNX4_NAME_MAX;
     40	} else {
     41		namelen = QNX4_SHORT_NAME_MAX;
     42	}
     43	thislen = strlen( de->di_fname );
     44	if ( thislen > namelen )
     45		thislen = namelen;
     46	if (len != thislen) {
     47		return 0;
     48	}
     49	if (strncmp(name, de->di_fname, len) == 0) {
     50		if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
     51			return 1;
     52		}
     53	}
     54	return 0;
     55}
     56
     57static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
     58	   const char *name, struct qnx4_inode_entry **res_dir, int *ino)
     59{
     60	unsigned long block, offset, blkofs;
     61	struct buffer_head *bh;
     62
     63	*res_dir = NULL;
     64	bh = NULL;
     65	block = offset = blkofs = 0;
     66	while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
     67		if (!bh) {
     68			block = qnx4_block_map(dir, blkofs);
     69			if (block)
     70				bh = sb_bread(dir->i_sb, block);
     71			if (!bh) {
     72				blkofs++;
     73				continue;
     74			}
     75		}
     76		*res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
     77		if (qnx4_match(len, name, bh, &offset)) {
     78			*ino = block * QNX4_INODES_PER_BLOCK +
     79			    (offset / QNX4_DIR_ENTRY_SIZE) - 1;
     80			return bh;
     81		}
     82		if (offset < bh->b_size) {
     83			continue;
     84		}
     85		brelse(bh);
     86		bh = NULL;
     87		offset = 0;
     88		blkofs++;
     89	}
     90	brelse(bh);
     91	*res_dir = NULL;
     92	return NULL;
     93}
     94
     95struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
     96{
     97	int ino;
     98	struct qnx4_inode_entry *de;
     99	struct qnx4_link_info *lnk;
    100	struct buffer_head *bh;
    101	const char *name = dentry->d_name.name;
    102	int len = dentry->d_name.len;
    103	struct inode *foundinode = NULL;
    104
    105	if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
    106		goto out;
    107	/* The entry is linked, let's get the real info */
    108	if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
    109		lnk = (struct qnx4_link_info *) de;
    110		ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
    111                    QNX4_INODES_PER_BLOCK +
    112		    lnk->dl_inode_ndx;
    113	}
    114	brelse(bh);
    115
    116	foundinode = qnx4_iget(dir->i_sb, ino);
    117	if (IS_ERR(foundinode))
    118		QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
    119			   PTR_ERR(foundinode)));
    120out:
    121	return d_splice_alias(foundinode, dentry);
    122}