// SPDX-License-Identifier: GPL-2.0-only/* * This contains encryption functions for per-file encryption. * * Copyright (C) 2015, Google, Inc. * Copyright (C) 2015, Motorola Mobility * * Written by Michael Halcrow, 2014. * * Filename encryption additions *	Uday Savagaonkar, 2014 * Encryption policy handling additions *	Ildar Muslukhov, 2014 * Add fscrypt_pullback_bio_page() *	Jaegeuk Kim, 2015. * * This has not yet undergone a rigorous security audit. * * The usage of AES-XTS should conform to recommendations in NIST * Special Publication 800-38E and IEEE P1619/D16. */ #include <crypto/skcipher.h>#include <linux/export.h>#include <linux/mempool.h>#include <linux/module.h>#include <linux/pagemap.h>#include <linux/ratelimit.h>#include <linux/scatterlist.h> #include "fscrypt_private.h" static unsigned int num_prealloc_crypto_pages = 32; module_param(num_prealloc_crypto_pages, uint, 0444);MODULE_PARM_DESC(num_prealloc_crypto_pages,		"Number of crypto pages to preallocate"); static mempool_t *fscrypt_bounce_page_pool = NULL; static DEFINE_MUTEX(fscrypt_init_mutex); struct kmem_cache *fscrypt_inode_info_cachep; static struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags){	if (WARN_ON_ONCE(!fscrypt_bounce_page_pool)) {		/*		 * Oops, the filesystem called a function that uses the bounce		 * page pool, but it didn't set needs_bounce_pages.		 */		return NULL;	}	return mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);} /** * fscrypt_free_bounce_page() - free a ciphertext bounce page * @bounce_page: the bounce page to free, or NULL * * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(). */void fscrypt_free_bounce_page(struct page *bounce_page){	if (!bounce_page)		return;	set_page_private(bounce_page, (unsigned long)NULL);	ClearPagePrivate(bounce_page);	mempool_free(bounce_page, fscrypt_bounce_page_pool);}EXPORT_SYMBOL(fscrypt_free_bounce_page); /* * Generate the IV for the given data unit index within the given file. * For filenames encryption, index == 0. * * Keep this in sync with fscrypt_limit_io_blocks().  fscrypt_limit_io_blocks() * needs to know about any IV generation methods where the low bits of IV don't * simply contain the data unit index (e.g., IV_INO_LBLK_32). */void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index,			 const struct fscrypt_inode_info *ci){	u8 flags = fscrypt_policy_flags(&ci->ci_policy); 	memset(iv, 0, sizeof(*iv)); 	if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) {		WARN_ON_ONCE(index > U32_MAX);		WARN_ON_ONCE(ci->ci_inode->i_ino > U32_MAX);		index |= (u64)ci->ci_inode->i_ino << 32;	} else if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) {		WARN_ON_ONCE(index > U32_MAX);		index = (u32)(ci->ci_hashed_ino + index);	} else if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {		memcpy(iv->nonce, ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE);	}	iv->index = cpu_to_le64(index);} /* Encrypt or decrypt a single "data unit" of file contents. */static int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci,				   fscrypt_direction_t rw, u64 index,				   struct page *src_page,				   struct page *dest_page, unsigned int len,				   unsigned int offs){	struct crypto_sync_skcipher *tfm;	union fscrypt_iv iv;	struct scatterlist dst, src;	int err; 	if (WARN_ON_ONCE(ci == NULL)) /* File hasn't been opened yet? */		return -ENOKEY;	tfm = ci->ci_enc_key.tfm;	if (WARN_ON_ONCE(tfm == NULL)) /* Called on block-based filesystem? */		return -ENOKEY; 	if (WARN_ON_ONCE(len <= 0))		return -EINVAL;	if (WARN_ON_ONCE(len % FSCRYPT_CONTENTS_ALIGNMENT != 0))		return -EINVAL; 	fscrypt_generate_iv(&iv, index, ci); 	{		SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);		skcipher_request_set_callback(req,					      CRYPTO_TFM_REQ_MAY_BACKLOG |						      CRYPTO_TFM_REQ_MAY_SLEEP,					      NULL, NULL);		sg_init_table(&dst, 1);		sg_set_page(&dst, dest_page, len, offs);		sg_init_table(&src, 1);		sg_set_page(&src, src_page, len, offs);		skcipher_request_set_crypt(req, &src, &dst, len, &iv);		if (rw == FS_DECRYPT)			err = crypto_skcipher_decrypt(req);		else			err = crypto_skcipher_encrypt(req);	}	if (err)		fscrypt_err(ci->ci_inode,			    "%scryption failed for data unit %llu: %d",			    (rw == FS_DECRYPT ? "De" : "En"), index, err);	return err;} /** * fscrypt_encrypt_pagecache_blocks() - Encrypt data from a pagecache folio * @folio: the locked pagecache folio containing the data to encrypt * @len: size of the data to encrypt, in bytes * @offs: offset within @page of the data to encrypt, in bytes * @gfp_flags: memory allocation flags; see details below * * This allocates a new bounce page and encrypts the given data into it.  The * length and offset of the data must be aligned to the file's crypto data unit * size.  Alignment to the filesystem block size fulfills this requirement, as * the filesystem block size is always a multiple of the data unit size. * * In the bounce page, the ciphertext data will be located at the same offset at * which the plaintext data was located in the source page.  Any other parts of * the bounce page will be left uninitialized. * * This is for use by the ->writepages() method of non-block-based filesystems. * * The bounce page allocation is mempool-backed, so it will always succeed when * @gfp_flags includes __GFP_DIRECT_RECLAIM, e.g. when it's GFP_NOFS.  However, * only the first page of each bio can be allocated this way.  To prevent * deadlocks, for any additional pages a mask like GFP_NOWAIT must be used. * * Return: the new encrypted bounce page on success; an ERR_PTR() on failure */struct page *fscrypt_encrypt_pagecache_blocks(struct folio *folio,		size_t len, size_t offs, gfp_t gfp_flags){	const struct inode *inode = folio->mapping->host;	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);	unsigned int du_bits;	unsigned int du_size;	struct page *ciphertext_page;	u64 index;	unsigned int i;	int err; 	if (WARN_ON_ONCE(ci == NULL)) /* File hasn't been opened yet? */		return ERR_PTR(-ENOKEY); 	du_bits = ci->ci_data_unit_bits;	du_size = 1U << du_bits;	index = (folio_pos(folio) + offs) >> du_bits; 	VM_BUG_ON_FOLIO(folio_test_large(folio), folio);	if (WARN_ON_ONCE(!folio_test_locked(folio)))		return ERR_PTR(-EINVAL); 	if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, du_size)))		return ERR_PTR(-EINVAL); 	ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);	if (!ciphertext_page)		return ERR_PTR(-ENOMEM); 	for (i = offs; i < offs + len; i += du_size, index++) {		err = fscrypt_crypt_data_unit(ci, FS_ENCRYPT, index,					      &folio->page, ciphertext_page,					      du_size, i);		if (err) {			fscrypt_free_bounce_page(ciphertext_page);			return ERR_PTR(err);		}	}	SetPagePrivate(ciphertext_page);	set_page_private(ciphertext_page, (unsigned long)folio);	return ciphertext_page;}EXPORT_SYMBOL(fscrypt_encrypt_pagecache_blocks); /** * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place * @inode:     The inode to which this block belongs * @page:      The page containing the block to encrypt * @len:       Size of block to encrypt.  This must be a multiple of *		FSCRYPT_CONTENTS_ALIGNMENT. * @offs:      Byte offset within @page at which the block to encrypt begins * @lblk_num:  Filesystem logical block number of the block, i.e. the 0-based *		number of the block within the file * * Encrypt a possibly-compressed filesystem block that is located in an * arbitrary page, not necessarily in the original pagecache page.  The @inode * and @lblk_num must be specified, as they can't be determined from @page. * * This function only supports non-block-based filesystems that don't support * sub-block data units (as indicated by the fscrypt_operations fields). * * Return: 0 on success; -errno on failure */int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,				  unsigned int len, unsigned int offs,				  u64 lblk_num){	if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))		return -EOPNOTSUPP;	return fscrypt_crypt_data_unit(fscrypt_get_inode_info_raw(inode),				       FS_ENCRYPT, lblk_num, page, page, len,				       offs);}EXPORT_SYMBOL(fscrypt_encrypt_block_inplace); /** * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place * @inode:     The inode to which this block belongs * @page:      The page containing the block to decrypt * @len:       Size of block to decrypt.  This must be a multiple of *		FSCRYPT_CONTENTS_ALIGNMENT. * @offs:      Byte offset within @page at which the block to decrypt begins * @lblk_num:  Filesystem logical block number of the block, i.e. the 0-based *		number of the block within the file * * Decrypt a possibly-compressed filesystem block that is located in an * arbitrary page, not necessarily in the original pagecache page.  The @inode * and @lblk_num must be specified, as they can't be determined from @page. * * This function only supports non-block-based filesystems that don't support * sub-block data units (as indicated by the fscrypt_operations fields). * * Return: 0 on success; -errno on failure */int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,				  unsigned int len, unsigned int offs,				  u64 lblk_num){	if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))		return -EOPNOTSUPP;	return fscrypt_crypt_data_unit(fscrypt_get_inode_info_raw(inode),				       FS_DECRYPT, lblk_num, page, page, len,				       offs);}EXPORT_SYMBOL(fscrypt_decrypt_block_inplace); /** * fscrypt_initialize() - allocate major buffers for fs encryption. * @sb: the filesystem superblock * * We only call this when we start accessing encrypted files, since it * results in memory getting allocated that wouldn't otherwise be used. * * Return: 0 on success; -errno on failure */int fscrypt_initialize(struct super_block *sb){	mempool_t *pool; 	/* pairs with smp_store_release() below */	if (smp_load_acquire(&fscrypt_bounce_page_pool))		return 0; 	/* No need to allocate a bounce page pool if this FS won't use it. */	if (!sb->s_cop->needs_bounce_pages)		return 0; 	guard(mutex)(&fscrypt_init_mutex);	if (fscrypt_bounce_page_pool)		return 0; 	pool = mempool_create_page_pool(num_prealloc_crypto_pages, 0);	if (!pool)		return -ENOMEM;	/* pairs with smp_load_acquire() above */	smp_store_release(&fscrypt_bounce_page_pool, pool);	return 0;} void fscrypt_msg(const struct inode *inode, const char *level,		 const char *fmt, ...){	static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,				      DEFAULT_RATELIMIT_BURST);	struct va_format vaf;	va_list args; 	if (!__ratelimit(&rs))		return; 	va_start(args, fmt);	vaf.fmt = fmt;	vaf.va = &args;	if (inode && inode->i_ino)		printk("%sfscrypt (%s, inode %llu): %pV\n",		       level, inode->i_sb->s_id, inode->i_ino, &vaf);	else if (inode)		printk("%sfscrypt (%s): %pV\n", level, inode->i_sb->s_id, &vaf);	else		printk("%sfscrypt: %pV\n", level, &vaf);	va_end(args);} static int __init fscrypt_init(void){	fscrypt_inode_info_cachep = KMEM_CACHE(fscrypt_inode_info,					       SLAB_RECLAIM_ACCOUNT |					       SLAB_PANIC);	fscrypt_init_keyring();	return 0;}late_initcall(fscrypt_init)