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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super.c (16365B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Squashfs - a compressed read only filesystem for Linux
      4 *
      5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
      6 * Phillip Lougher <phillip@squashfs.org.uk>
      7 *
      8 * super.c
      9 */
     10
     11/*
     12 * This file implements code to read the superblock, read and initialise
     13 * in-memory structures at mount time, and all the VFS glue code to register
     14 * the filesystem.
     15 */
     16
     17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
     18
     19#include <linux/blkdev.h>
     20#include <linux/fs.h>
     21#include <linux/fs_context.h>
     22#include <linux/fs_parser.h>
     23#include <linux/vfs.h>
     24#include <linux/slab.h>
     25#include <linux/mutex.h>
     26#include <linux/seq_file.h>
     27#include <linux/pagemap.h>
     28#include <linux/init.h>
     29#include <linux/module.h>
     30#include <linux/magic.h>
     31#include <linux/xattr.h>
     32#include <linux/backing-dev.h>
     33
     34#include "squashfs_fs.h"
     35#include "squashfs_fs_sb.h"
     36#include "squashfs_fs_i.h"
     37#include "squashfs.h"
     38#include "decompressor.h"
     39#include "xattr.h"
     40
     41static struct file_system_type squashfs_fs_type;
     42static const struct super_operations squashfs_super_ops;
     43
     44enum Opt_errors {
     45	Opt_errors_continue,
     46	Opt_errors_panic,
     47};
     48
     49enum squashfs_param {
     50	Opt_errors,
     51};
     52
     53struct squashfs_mount_opts {
     54	enum Opt_errors errors;
     55};
     56
     57static const struct constant_table squashfs_param_errors[] = {
     58	{"continue",   Opt_errors_continue },
     59	{"panic",      Opt_errors_panic },
     60	{}
     61};
     62
     63static const struct fs_parameter_spec squashfs_fs_parameters[] = {
     64	fsparam_enum("errors", Opt_errors, squashfs_param_errors),
     65	{}
     66};
     67
     68static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
     69{
     70	struct squashfs_mount_opts *opts = fc->fs_private;
     71	struct fs_parse_result result;
     72	int opt;
     73
     74	opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
     75	if (opt < 0)
     76		return opt;
     77
     78	switch (opt) {
     79	case Opt_errors:
     80		opts->errors = result.uint_32;
     81		break;
     82	default:
     83		return -EINVAL;
     84	}
     85
     86	return 0;
     87}
     88
     89static const struct squashfs_decompressor *supported_squashfs_filesystem(
     90	struct fs_context *fc,
     91	short major, short minor, short id)
     92{
     93	const struct squashfs_decompressor *decompressor;
     94
     95	if (major < SQUASHFS_MAJOR) {
     96		errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
     97		       "filesystems are unsupported", major, minor);
     98		return NULL;
     99	} else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
    100		errorf(fc, "Major/Minor mismatch, trying to mount newer "
    101		       "%d.%d filesystem", major, minor);
    102		errorf(fc, "Please update your kernel");
    103		return NULL;
    104	}
    105
    106	decompressor = squashfs_lookup_decompressor(id);
    107	if (!decompressor->supported) {
    108		errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
    109		       decompressor->name);
    110		return NULL;
    111	}
    112
    113	return decompressor;
    114}
    115
    116static int squashfs_bdi_init(struct super_block *sb)
    117{
    118	int err;
    119	unsigned int major = MAJOR(sb->s_dev);
    120	unsigned int minor = MINOR(sb->s_dev);
    121
    122	bdi_put(sb->s_bdi);
    123	sb->s_bdi = &noop_backing_dev_info;
    124
    125	err = super_setup_bdi_name(sb, "squashfs_%u_%u", major, minor);
    126	if (err)
    127		return err;
    128
    129	sb->s_bdi->ra_pages = 0;
    130	sb->s_bdi->io_pages = 0;
    131
    132	return 0;
    133}
    134
    135static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
    136{
    137	struct squashfs_mount_opts *opts = fc->fs_private;
    138	struct squashfs_sb_info *msblk;
    139	struct squashfs_super_block *sblk = NULL;
    140	struct inode *root;
    141	long long root_inode;
    142	unsigned short flags;
    143	unsigned int fragments;
    144	u64 lookup_table_start, xattr_id_table_start, next_table;
    145	int err;
    146
    147	TRACE("Entered squashfs_fill_superblock\n");
    148
    149	/*
    150	 * squashfs provides 'backing_dev_info' in order to disable read-ahead. For
    151	 * squashfs, I/O is not deferred, it is done immediately in read_folio,
    152	 * which means the user would always have to wait their own I/O. So the effect
    153	 * of readahead is very weak for squashfs. squashfs_bdi_init will set
    154	 * sb->s_bdi->ra_pages and sb->s_bdi->io_pages to 0 and close readahead for
    155	 * squashfs.
    156	 */
    157	err = squashfs_bdi_init(sb);
    158	if (err) {
    159		errorf(fc, "squashfs init bdi failed");
    160		return err;
    161	}
    162
    163	sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
    164	if (sb->s_fs_info == NULL) {
    165		ERROR("Failed to allocate squashfs_sb_info\n");
    166		return -ENOMEM;
    167	}
    168	msblk = sb->s_fs_info;
    169
    170	msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
    171
    172	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
    173	msblk->devblksize_log2 = ffz(~msblk->devblksize);
    174
    175	mutex_init(&msblk->meta_index_mutex);
    176
    177	/*
    178	 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
    179	 * are not beyond filesystem end.  But as we're using
    180	 * squashfs_read_table here to read the superblock (including the value
    181	 * of bytes_used) we need to set it to an initial sensible dummy value
    182	 */
    183	msblk->bytes_used = sizeof(*sblk);
    184	sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
    185
    186	if (IS_ERR(sblk)) {
    187		errorf(fc, "unable to read squashfs_super_block");
    188		err = PTR_ERR(sblk);
    189		sblk = NULL;
    190		goto failed_mount;
    191	}
    192
    193	err = -EINVAL;
    194
    195	/* Check it is a SQUASHFS superblock */
    196	sb->s_magic = le32_to_cpu(sblk->s_magic);
    197	if (sb->s_magic != SQUASHFS_MAGIC) {
    198		if (!(fc->sb_flags & SB_SILENT))
    199			errorf(fc, "Can't find a SQUASHFS superblock on %pg",
    200			       sb->s_bdev);
    201		goto failed_mount;
    202	}
    203
    204	/* Check the MAJOR & MINOR versions and lookup compression type */
    205	msblk->decompressor = supported_squashfs_filesystem(
    206			fc,
    207			le16_to_cpu(sblk->s_major),
    208			le16_to_cpu(sblk->s_minor),
    209			le16_to_cpu(sblk->compression));
    210	if (msblk->decompressor == NULL)
    211		goto failed_mount;
    212
    213	/* Check the filesystem does not extend beyond the end of the
    214	   block device */
    215	msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
    216	if (msblk->bytes_used < 0 ||
    217	    msblk->bytes_used > bdev_nr_bytes(sb->s_bdev))
    218		goto failed_mount;
    219
    220	/* Check block size for sanity */
    221	msblk->block_size = le32_to_cpu(sblk->block_size);
    222	if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
    223		goto insanity;
    224
    225	/*
    226	 * Check the system page size is not larger than the filesystem
    227	 * block size (by default 128K).  This is currently not supported.
    228	 */
    229	if (PAGE_SIZE > msblk->block_size) {
    230		errorf(fc, "Page size > filesystem block size (%d).  This is "
    231		       "currently not supported!", msblk->block_size);
    232		goto failed_mount;
    233	}
    234
    235	/* Check block log for sanity */
    236	msblk->block_log = le16_to_cpu(sblk->block_log);
    237	if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
    238		goto failed_mount;
    239
    240	/* Check that block_size and block_log match */
    241	if (msblk->block_size != (1 << msblk->block_log))
    242		goto insanity;
    243
    244	/* Check the root inode for sanity */
    245	root_inode = le64_to_cpu(sblk->root_inode);
    246	if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
    247		goto insanity;
    248
    249	msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
    250	msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
    251	msblk->inodes = le32_to_cpu(sblk->inodes);
    252	msblk->fragments = le32_to_cpu(sblk->fragments);
    253	msblk->ids = le16_to_cpu(sblk->no_ids);
    254	flags = le16_to_cpu(sblk->flags);
    255
    256	TRACE("Found valid superblock on %pg\n", sb->s_bdev);
    257	TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
    258				? "un" : "");
    259	TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
    260				? "un" : "");
    261	TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
    262	TRACE("Block size %d\n", msblk->block_size);
    263	TRACE("Number of inodes %d\n", msblk->inodes);
    264	TRACE("Number of fragments %d\n", msblk->fragments);
    265	TRACE("Number of ids %d\n", msblk->ids);
    266	TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
    267	TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
    268	TRACE("sblk->fragment_table_start %llx\n",
    269		(u64) le64_to_cpu(sblk->fragment_table_start));
    270	TRACE("sblk->id_table_start %llx\n",
    271		(u64) le64_to_cpu(sblk->id_table_start));
    272
    273	sb->s_maxbytes = MAX_LFS_FILESIZE;
    274	sb->s_time_min = 0;
    275	sb->s_time_max = U32_MAX;
    276	sb->s_flags |= SB_RDONLY;
    277	sb->s_op = &squashfs_super_ops;
    278
    279	err = -ENOMEM;
    280
    281	msblk->block_cache = squashfs_cache_init("metadata",
    282			SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
    283	if (msblk->block_cache == NULL)
    284		goto failed_mount;
    285
    286	/* Allocate read_page block */
    287	msblk->read_page = squashfs_cache_init("data",
    288		squashfs_max_decompressors(), msblk->block_size);
    289	if (msblk->read_page == NULL) {
    290		errorf(fc, "Failed to allocate read_page block");
    291		goto failed_mount;
    292	}
    293
    294	msblk->stream = squashfs_decompressor_setup(sb, flags);
    295	if (IS_ERR(msblk->stream)) {
    296		err = PTR_ERR(msblk->stream);
    297		msblk->stream = NULL;
    298		goto insanity;
    299	}
    300
    301	/* Handle xattrs */
    302	sb->s_xattr = squashfs_xattr_handlers;
    303	xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
    304	if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
    305		next_table = msblk->bytes_used;
    306		goto allocate_id_index_table;
    307	}
    308
    309	/* Allocate and read xattr id lookup table */
    310	msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
    311		xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
    312	if (IS_ERR(msblk->xattr_id_table)) {
    313		errorf(fc, "unable to read xattr id index table");
    314		err = PTR_ERR(msblk->xattr_id_table);
    315		msblk->xattr_id_table = NULL;
    316		if (err != -ENOTSUPP)
    317			goto failed_mount;
    318	}
    319	next_table = msblk->xattr_table;
    320
    321allocate_id_index_table:
    322	/* Allocate and read id index table */
    323	msblk->id_table = squashfs_read_id_index_table(sb,
    324		le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
    325	if (IS_ERR(msblk->id_table)) {
    326		errorf(fc, "unable to read id index table");
    327		err = PTR_ERR(msblk->id_table);
    328		msblk->id_table = NULL;
    329		goto failed_mount;
    330	}
    331	next_table = le64_to_cpu(msblk->id_table[0]);
    332
    333	/* Handle inode lookup table */
    334	lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
    335	if (lookup_table_start == SQUASHFS_INVALID_BLK)
    336		goto handle_fragments;
    337
    338	/* Allocate and read inode lookup table */
    339	msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
    340		lookup_table_start, next_table, msblk->inodes);
    341	if (IS_ERR(msblk->inode_lookup_table)) {
    342		errorf(fc, "unable to read inode lookup table");
    343		err = PTR_ERR(msblk->inode_lookup_table);
    344		msblk->inode_lookup_table = NULL;
    345		goto failed_mount;
    346	}
    347	next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
    348
    349	sb->s_export_op = &squashfs_export_ops;
    350
    351handle_fragments:
    352	fragments = msblk->fragments;
    353	if (fragments == 0)
    354		goto check_directory_table;
    355
    356	msblk->fragment_cache = squashfs_cache_init("fragment",
    357		SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
    358	if (msblk->fragment_cache == NULL) {
    359		err = -ENOMEM;
    360		goto failed_mount;
    361	}
    362
    363	/* Allocate and read fragment index table */
    364	msblk->fragment_index = squashfs_read_fragment_index_table(sb,
    365		le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
    366	if (IS_ERR(msblk->fragment_index)) {
    367		errorf(fc, "unable to read fragment index table");
    368		err = PTR_ERR(msblk->fragment_index);
    369		msblk->fragment_index = NULL;
    370		goto failed_mount;
    371	}
    372	next_table = le64_to_cpu(msblk->fragment_index[0]);
    373
    374check_directory_table:
    375	/* Sanity check directory_table */
    376	if (msblk->directory_table > next_table) {
    377		err = -EINVAL;
    378		goto insanity;
    379	}
    380
    381	/* Sanity check inode_table */
    382	if (msblk->inode_table >= msblk->directory_table) {
    383		err = -EINVAL;
    384		goto insanity;
    385	}
    386
    387	/* allocate root */
    388	root = new_inode(sb);
    389	if (!root) {
    390		err = -ENOMEM;
    391		goto failed_mount;
    392	}
    393
    394	err = squashfs_read_inode(root, root_inode);
    395	if (err) {
    396		make_bad_inode(root);
    397		iput(root);
    398		goto failed_mount;
    399	}
    400	insert_inode_hash(root);
    401
    402	sb->s_root = d_make_root(root);
    403	if (sb->s_root == NULL) {
    404		ERROR("Root inode create failed\n");
    405		err = -ENOMEM;
    406		goto failed_mount;
    407	}
    408
    409	TRACE("Leaving squashfs_fill_super\n");
    410	kfree(sblk);
    411	return 0;
    412
    413insanity:
    414	errorf(fc, "squashfs image failed sanity check");
    415failed_mount:
    416	squashfs_cache_delete(msblk->block_cache);
    417	squashfs_cache_delete(msblk->fragment_cache);
    418	squashfs_cache_delete(msblk->read_page);
    419	squashfs_decompressor_destroy(msblk);
    420	kfree(msblk->inode_lookup_table);
    421	kfree(msblk->fragment_index);
    422	kfree(msblk->id_table);
    423	kfree(msblk->xattr_id_table);
    424	kfree(sb->s_fs_info);
    425	sb->s_fs_info = NULL;
    426	kfree(sblk);
    427	return err;
    428}
    429
    430static int squashfs_get_tree(struct fs_context *fc)
    431{
    432	return get_tree_bdev(fc, squashfs_fill_super);
    433}
    434
    435static int squashfs_reconfigure(struct fs_context *fc)
    436{
    437	struct super_block *sb = fc->root->d_sb;
    438	struct squashfs_sb_info *msblk = sb->s_fs_info;
    439	struct squashfs_mount_opts *opts = fc->fs_private;
    440
    441	sync_filesystem(fc->root->d_sb);
    442	fc->sb_flags |= SB_RDONLY;
    443
    444	msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
    445
    446	return 0;
    447}
    448
    449static void squashfs_free_fs_context(struct fs_context *fc)
    450{
    451	kfree(fc->fs_private);
    452}
    453
    454static const struct fs_context_operations squashfs_context_ops = {
    455	.get_tree	= squashfs_get_tree,
    456	.free		= squashfs_free_fs_context,
    457	.parse_param	= squashfs_parse_param,
    458	.reconfigure	= squashfs_reconfigure,
    459};
    460
    461static int squashfs_show_options(struct seq_file *s, struct dentry *root)
    462{
    463	struct super_block *sb = root->d_sb;
    464	struct squashfs_sb_info *msblk = sb->s_fs_info;
    465
    466	if (msblk->panic_on_errors)
    467		seq_puts(s, ",errors=panic");
    468	else
    469		seq_puts(s, ",errors=continue");
    470
    471	return 0;
    472}
    473
    474static int squashfs_init_fs_context(struct fs_context *fc)
    475{
    476	struct squashfs_mount_opts *opts;
    477
    478	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
    479	if (!opts)
    480		return -ENOMEM;
    481
    482	fc->fs_private = opts;
    483	fc->ops = &squashfs_context_ops;
    484	return 0;
    485}
    486
    487static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
    488{
    489	struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
    490	u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
    491
    492	TRACE("Entered squashfs_statfs\n");
    493
    494	buf->f_type = SQUASHFS_MAGIC;
    495	buf->f_bsize = msblk->block_size;
    496	buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
    497	buf->f_bfree = buf->f_bavail = 0;
    498	buf->f_files = msblk->inodes;
    499	buf->f_ffree = 0;
    500	buf->f_namelen = SQUASHFS_NAME_LEN;
    501	buf->f_fsid = u64_to_fsid(id);
    502
    503	return 0;
    504}
    505
    506
    507static void squashfs_put_super(struct super_block *sb)
    508{
    509	if (sb->s_fs_info) {
    510		struct squashfs_sb_info *sbi = sb->s_fs_info;
    511		squashfs_cache_delete(sbi->block_cache);
    512		squashfs_cache_delete(sbi->fragment_cache);
    513		squashfs_cache_delete(sbi->read_page);
    514		squashfs_decompressor_destroy(sbi);
    515		kfree(sbi->id_table);
    516		kfree(sbi->fragment_index);
    517		kfree(sbi->meta_index);
    518		kfree(sbi->inode_lookup_table);
    519		kfree(sbi->xattr_id_table);
    520		kfree(sb->s_fs_info);
    521		sb->s_fs_info = NULL;
    522	}
    523}
    524
    525static struct kmem_cache *squashfs_inode_cachep;
    526
    527
    528static void init_once(void *foo)
    529{
    530	struct squashfs_inode_info *ei = foo;
    531
    532	inode_init_once(&ei->vfs_inode);
    533}
    534
    535
    536static int __init init_inodecache(void)
    537{
    538	squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
    539		sizeof(struct squashfs_inode_info), 0,
    540		SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
    541		init_once);
    542
    543	return squashfs_inode_cachep ? 0 : -ENOMEM;
    544}
    545
    546
    547static void destroy_inodecache(void)
    548{
    549	/*
    550	 * Make sure all delayed rcu free inodes are flushed before we
    551	 * destroy cache.
    552	 */
    553	rcu_barrier();
    554	kmem_cache_destroy(squashfs_inode_cachep);
    555}
    556
    557
    558static int __init init_squashfs_fs(void)
    559{
    560	int err = init_inodecache();
    561
    562	if (err)
    563		return err;
    564
    565	err = register_filesystem(&squashfs_fs_type);
    566	if (err) {
    567		destroy_inodecache();
    568		return err;
    569	}
    570
    571	pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
    572
    573	return 0;
    574}
    575
    576
    577static void __exit exit_squashfs_fs(void)
    578{
    579	unregister_filesystem(&squashfs_fs_type);
    580	destroy_inodecache();
    581}
    582
    583
    584static struct inode *squashfs_alloc_inode(struct super_block *sb)
    585{
    586	struct squashfs_inode_info *ei =
    587		alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL);
    588
    589	return ei ? &ei->vfs_inode : NULL;
    590}
    591
    592
    593static void squashfs_free_inode(struct inode *inode)
    594{
    595	kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
    596}
    597
    598static struct file_system_type squashfs_fs_type = {
    599	.owner = THIS_MODULE,
    600	.name = "squashfs",
    601	.init_fs_context = squashfs_init_fs_context,
    602	.parameters = squashfs_fs_parameters,
    603	.kill_sb = kill_block_super,
    604	.fs_flags = FS_REQUIRES_DEV
    605};
    606MODULE_ALIAS_FS("squashfs");
    607
    608static const struct super_operations squashfs_super_ops = {
    609	.alloc_inode = squashfs_alloc_inode,
    610	.free_inode = squashfs_free_inode,
    611	.statfs = squashfs_statfs,
    612	.put_super = squashfs_put_super,
    613	.show_options = squashfs_show_options,
    614};
    615
    616module_init(init_squashfs_fs);
    617module_exit(exit_squashfs_fs);
    618MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
    619MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
    620MODULE_LICENSE("GPL");