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-rw-r--r--fs/crypto/crypto.c411
1 files changed, 411 insertions, 0 deletions
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
new file mode 100644
index 0000000000..6a837e4b80
--- /dev/null
+++ b/fs/crypto/crypto.c
@@ -0,0 +1,411 @@
+// 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 <linux/pagemap.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/ratelimit.h>
+#include <crypto/skcipher.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 struct workqueue_struct *fscrypt_read_workqueue;
+static DEFINE_MUTEX(fscrypt_init_mutex);
+
+struct kmem_cache *fscrypt_info_cachep;
+
+void fscrypt_enqueue_decrypt_work(struct work_struct *work)
+{
+ queue_work(fscrypt_read_workqueue, work);
+}
+EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
+
+struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
+{
+ 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(),
+ * or by fscrypt_alloc_bounce_page() directly.
+ */
+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 logical block number within the given file.
+ * For filenames encryption, lblk_num == 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 lblk_num (e.g., IV_INO_LBLK_32).
+ */
+void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
+ const struct fscrypt_info *ci)
+{
+ u8 flags = fscrypt_policy_flags(&ci->ci_policy);
+
+ memset(iv, 0, ci->ci_mode->ivsize);
+
+ if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) {
+ WARN_ON_ONCE(lblk_num > U32_MAX);
+ WARN_ON_ONCE(ci->ci_inode->i_ino > U32_MAX);
+ lblk_num |= (u64)ci->ci_inode->i_ino << 32;
+ } else if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) {
+ WARN_ON_ONCE(lblk_num > U32_MAX);
+ lblk_num = (u32)(ci->ci_hashed_ino + lblk_num);
+ } else if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {
+ memcpy(iv->nonce, ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE);
+ }
+ iv->lblk_num = cpu_to_le64(lblk_num);
+}
+
+/* Encrypt or decrypt a single filesystem block of file contents */
+int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
+ u64 lblk_num, struct page *src_page,
+ struct page *dest_page, unsigned int len,
+ unsigned int offs, gfp_t gfp_flags)
+{
+ union fscrypt_iv iv;
+ struct skcipher_request *req = NULL;
+ DECLARE_CRYPTO_WAIT(wait);
+ struct scatterlist dst, src;
+ struct fscrypt_info *ci = inode->i_crypt_info;
+ struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
+ int res = 0;
+
+ if (WARN_ON_ONCE(len <= 0))
+ return -EINVAL;
+ if (WARN_ON_ONCE(len % FSCRYPT_CONTENTS_ALIGNMENT != 0))
+ return -EINVAL;
+
+ fscrypt_generate_iv(&iv, lblk_num, ci);
+
+ req = skcipher_request_alloc(tfm, gfp_flags);
+ if (!req)
+ return -ENOMEM;
+
+ skcipher_request_set_callback(
+ req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ crypto_req_done, &wait);
+
+ 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)
+ res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
+ else
+ res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
+ skcipher_request_free(req);
+ if (res) {
+ fscrypt_err(inode, "%scryption failed for block %llu: %d",
+ (rw == FS_DECRYPT ? "De" : "En"), lblk_num, res);
+ return res;
+ }
+ return 0;
+}
+
+/**
+ * fscrypt_encrypt_pagecache_blocks() - Encrypt filesystem blocks from a
+ * pagecache page
+ * @page: The locked pagecache page containing the block(s) to encrypt
+ * @len: Total size of the block(s) to encrypt. Must be a nonzero
+ * multiple of the filesystem's block size.
+ * @offs: Byte offset within @page of the first block to encrypt. Must be
+ * a multiple of the filesystem's block size.
+ * @gfp_flags: Memory allocation flags. See details below.
+ *
+ * A new bounce page is allocated, and the specified block(s) are encrypted into
+ * it. In the bounce page, the ciphertext block(s) will be located at the same
+ * offsets at which the plaintext block(s) were located in the source page; any
+ * other parts of the bounce page will be left uninitialized. However, normally
+ * blocksize == PAGE_SIZE and the whole page is encrypted at once.
+ *
+ * This is for use by the filesystem's ->writepages() method.
+ *
+ * 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 page *page,
+ unsigned int len,
+ unsigned int offs,
+ gfp_t gfp_flags)
+
+{
+ const struct inode *inode = page->mapping->host;
+ const unsigned int blockbits = inode->i_blkbits;
+ const unsigned int blocksize = 1 << blockbits;
+ struct page *ciphertext_page;
+ u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
+ (offs >> blockbits);
+ unsigned int i;
+ int err;
+
+ if (WARN_ON_ONCE(!PageLocked(page)))
+ return ERR_PTR(-EINVAL);
+
+ if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
+ 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 += blocksize, lblk_num++) {
+ err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num,
+ page, ciphertext_page,
+ blocksize, i, gfp_flags);
+ if (err) {
+ fscrypt_free_bounce_page(ciphertext_page);
+ return ERR_PTR(err);
+ }
+ }
+ SetPagePrivate(ciphertext_page);
+ set_page_private(ciphertext_page, (unsigned long)page);
+ 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
+ * @gfp_flags: Memory allocation flags
+ *
+ * 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.
+ *
+ * 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, gfp_t gfp_flags)
+{
+ return fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page, page,
+ len, offs, gfp_flags);
+}
+EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
+
+/**
+ * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a
+ * pagecache folio
+ * @folio: The locked pagecache folio containing the block(s) to decrypt
+ * @len: Total size of the block(s) to decrypt. Must be a nonzero
+ * multiple of the filesystem's block size.
+ * @offs: Byte offset within @folio of the first block to decrypt. Must be
+ * a multiple of the filesystem's block size.
+ *
+ * The specified block(s) are decrypted in-place within the pagecache folio,
+ * which must still be locked and not uptodate.
+ *
+ * This is for use by the filesystem's ->readahead() method.
+ *
+ * Return: 0 on success; -errno on failure
+ */
+int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len,
+ size_t offs)
+{
+ const struct inode *inode = folio->mapping->host;
+ const unsigned int blockbits = inode->i_blkbits;
+ const unsigned int blocksize = 1 << blockbits;
+ u64 lblk_num = ((u64)folio->index << (PAGE_SHIFT - blockbits)) +
+ (offs >> blockbits);
+ size_t i;
+ int err;
+
+ if (WARN_ON_ONCE(!folio_test_locked(folio)))
+ return -EINVAL;
+
+ if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
+ return -EINVAL;
+
+ for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
+ struct page *page = folio_page(folio, i >> PAGE_SHIFT);
+
+ err = fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page,
+ page, blocksize, i & ~PAGE_MASK,
+ GFP_NOFS);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks);
+
+/**
+ * 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.
+ *
+ * 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)
+{
+ return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
+ len, offs, GFP_NOFS);
+}
+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)
+{
+ int err = 0;
+ mempool_t *pool;
+
+ /* pairs with smp_store_release() below */
+ if (likely(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->flags & FS_CFLG_OWN_PAGES)
+ return 0;
+
+ mutex_lock(&fscrypt_init_mutex);
+ if (fscrypt_bounce_page_pool)
+ goto out_unlock;
+
+ err = -ENOMEM;
+ pool = mempool_create_page_pool(num_prealloc_crypto_pages, 0);
+ if (!pool)
+ goto out_unlock;
+ /* pairs with smp_load_acquire() above */
+ smp_store_release(&fscrypt_bounce_page_pool, pool);
+ err = 0;
+out_unlock:
+ mutex_unlock(&fscrypt_init_mutex);
+ return err;
+}
+
+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 %lu): %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);
+}
+
+/**
+ * fscrypt_init() - Set up for fs encryption.
+ *
+ * Return: 0 on success; -errno on failure
+ */
+static int __init fscrypt_init(void)
+{
+ int err = -ENOMEM;
+
+ /*
+ * Use an unbound workqueue to allow bios to be decrypted in parallel
+ * even when they happen to complete on the same CPU. This sacrifices
+ * locality, but it's worthwhile since decryption is CPU-intensive.
+ *
+ * Also use a high-priority workqueue to prioritize decryption work,
+ * which blocks reads from completing, over regular application tasks.
+ */
+ fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
+ WQ_UNBOUND | WQ_HIGHPRI,
+ num_online_cpus());
+ if (!fscrypt_read_workqueue)
+ goto fail;
+
+ fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
+ if (!fscrypt_info_cachep)
+ goto fail_free_queue;
+
+ err = fscrypt_init_keyring();
+ if (err)
+ goto fail_free_info;
+
+ return 0;
+
+fail_free_info:
+ kmem_cache_destroy(fscrypt_info_cachep);
+fail_free_queue:
+ destroy_workqueue(fscrypt_read_workqueue);
+fail:
+ return err;
+}
+late_initcall(fscrypt_init)