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authorJaegeuk Kim <jaegeuk@kernel.org>2016-07-10 21:01:03 +0300
committerTheodore Ts'o <tytso@mit.edu>2016-07-10 21:01:03 +0300
commita7550b30ab709ffb9bbe48669adf7d8556f3698f (patch)
tree5ed986d93b2df41cad68bdfa0851604bb039d1d1 /fs/ext4/crypto.c
parentff0031d848a0cd7002606f9feef958de8d5edf19 (diff)
downloadlinux-a7550b30ab709ffb9bbe48669adf7d8556f3698f.tar.xz
ext4 crypto: migrate into vfs's crypto engine
This patch removes the most parts of internal crypto codes. And then, it modifies and adds some ext4-specific crypt codes to use the generic facility. Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/crypto.c')
-rw-r--r--fs/ext4/crypto.c536
1 files changed, 0 insertions, 536 deletions
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
deleted file mode 100644
index 6a6c27373b54..000000000000
--- a/fs/ext4/crypto.c
+++ /dev/null
@@ -1,536 +0,0 @@
-/*
- * linux/fs/ext4/crypto.c
- *
- * Copyright (C) 2015, Google, Inc.
- *
- * This contains encryption functions for ext4
- *
- * Written by Michael Halcrow, 2014.
- *
- * Filename encryption additions
- * Uday Savagaonkar, 2014
- * Encryption policy handling additions
- * Ildar Muslukhov, 2014
- *
- * 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 <keys/user-type.h>
-#include <keys/encrypted-type.h>
-#include <linux/ecryptfs.h>
-#include <linux/gfp.h>
-#include <linux/kernel.h>
-#include <linux/key.h>
-#include <linux/list.h>
-#include <linux/mempool.h>
-#include <linux/module.h>
-#include <linux/mutex.h>
-#include <linux/random.h>
-#include <linux/scatterlist.h>
-#include <linux/spinlock_types.h>
-#include <linux/namei.h>
-
-#include "ext4_extents.h"
-#include "xattr.h"
-
-/* Encryption added and removed here! (L: */
-
-static unsigned int num_prealloc_crypto_pages = 32;
-static unsigned int num_prealloc_crypto_ctxs = 128;
-
-module_param(num_prealloc_crypto_pages, uint, 0444);
-MODULE_PARM_DESC(num_prealloc_crypto_pages,
- "Number of crypto pages to preallocate");
-module_param(num_prealloc_crypto_ctxs, uint, 0444);
-MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
- "Number of crypto contexts to preallocate");
-
-static mempool_t *ext4_bounce_page_pool;
-
-static LIST_HEAD(ext4_free_crypto_ctxs);
-static DEFINE_SPINLOCK(ext4_crypto_ctx_lock);
-
-static struct kmem_cache *ext4_crypto_ctx_cachep;
-struct kmem_cache *ext4_crypt_info_cachep;
-
-/**
- * ext4_release_crypto_ctx() - Releases an encryption context
- * @ctx: The encryption context to release.
- *
- * If the encryption context was allocated from the pre-allocated pool, returns
- * it to that pool. Else, frees it.
- *
- * If there's a bounce page in the context, this frees that.
- */
-void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)
-{
- unsigned long flags;
-
- if (ctx->flags & EXT4_WRITE_PATH_FL && ctx->w.bounce_page)
- mempool_free(ctx->w.bounce_page, ext4_bounce_page_pool);
- ctx->w.bounce_page = NULL;
- ctx->w.control_page = NULL;
- if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
- kmem_cache_free(ext4_crypto_ctx_cachep, ctx);
- } else {
- spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
- list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
- spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
- }
-}
-
-/**
- * ext4_get_crypto_ctx() - Gets an encryption context
- * @inode: The inode for which we are doing the crypto
- *
- * Allocates and initializes an encryption context.
- *
- * Return: An allocated and initialized encryption context on success; error
- * value or NULL otherwise.
- */
-struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode,
- gfp_t gfp_flags)
-{
- struct ext4_crypto_ctx *ctx = NULL;
- int res = 0;
- unsigned long flags;
- struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
-
- if (ci == NULL)
- return ERR_PTR(-ENOKEY);
-
- /*
- * We first try getting the ctx from a free list because in
- * the common case the ctx will have an allocated and
- * initialized crypto tfm, so it's probably a worthwhile
- * optimization. For the bounce page, we first try getting it
- * from the kernel allocator because that's just about as fast
- * as getting it from a list and because a cache of free pages
- * should generally be a "last resort" option for a filesystem
- * to be able to do its job.
- */
- spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
- ctx = list_first_entry_or_null(&ext4_free_crypto_ctxs,
- struct ext4_crypto_ctx, free_list);
- if (ctx)
- list_del(&ctx->free_list);
- spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
- if (!ctx) {
- ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, gfp_flags);
- if (!ctx) {
- res = -ENOMEM;
- goto out;
- }
- ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
- } else {
- ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
- }
- ctx->flags &= ~EXT4_WRITE_PATH_FL;
-
-out:
- if (res) {
- if (!IS_ERR_OR_NULL(ctx))
- ext4_release_crypto_ctx(ctx);
- ctx = ERR_PTR(res);
- }
- return ctx;
-}
-
-struct workqueue_struct *ext4_read_workqueue;
-static DEFINE_MUTEX(crypto_init);
-
-/**
- * ext4_exit_crypto() - Shutdown the ext4 encryption system
- */
-void ext4_exit_crypto(void)
-{
- struct ext4_crypto_ctx *pos, *n;
-
- list_for_each_entry_safe(pos, n, &ext4_free_crypto_ctxs, free_list)
- kmem_cache_free(ext4_crypto_ctx_cachep, pos);
- INIT_LIST_HEAD(&ext4_free_crypto_ctxs);
- if (ext4_bounce_page_pool)
- mempool_destroy(ext4_bounce_page_pool);
- ext4_bounce_page_pool = NULL;
- if (ext4_read_workqueue)
- destroy_workqueue(ext4_read_workqueue);
- ext4_read_workqueue = NULL;
- if (ext4_crypto_ctx_cachep)
- kmem_cache_destroy(ext4_crypto_ctx_cachep);
- ext4_crypto_ctx_cachep = NULL;
- if (ext4_crypt_info_cachep)
- kmem_cache_destroy(ext4_crypt_info_cachep);
- ext4_crypt_info_cachep = NULL;
-}
-
-/**
- * ext4_init_crypto() - Set up for ext4 encryption.
- *
- * We only call this when we start accessing encrypted files, since it
- * results in memory getting allocated that wouldn't otherwise be used.
- *
- * Return: Zero on success, non-zero otherwise.
- */
-int ext4_init_crypto(void)
-{
- int i, res = -ENOMEM;
-
- mutex_lock(&crypto_init);
- if (ext4_read_workqueue)
- goto already_initialized;
- ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0);
- if (!ext4_read_workqueue)
- goto fail;
-
- ext4_crypto_ctx_cachep = KMEM_CACHE(ext4_crypto_ctx,
- SLAB_RECLAIM_ACCOUNT);
- if (!ext4_crypto_ctx_cachep)
- goto fail;
-
- ext4_crypt_info_cachep = KMEM_CACHE(ext4_crypt_info,
- SLAB_RECLAIM_ACCOUNT);
- if (!ext4_crypt_info_cachep)
- goto fail;
-
- for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
- struct ext4_crypto_ctx *ctx;
-
- ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);
- if (!ctx) {
- res = -ENOMEM;
- goto fail;
- }
- list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
- }
-
- ext4_bounce_page_pool =
- mempool_create_page_pool(num_prealloc_crypto_pages, 0);
- if (!ext4_bounce_page_pool) {
- res = -ENOMEM;
- goto fail;
- }
-already_initialized:
- mutex_unlock(&crypto_init);
- return 0;
-fail:
- ext4_exit_crypto();
- mutex_unlock(&crypto_init);
- return res;
-}
-
-void ext4_restore_control_page(struct page *data_page)
-{
- struct ext4_crypto_ctx *ctx =
- (struct ext4_crypto_ctx *)page_private(data_page);
-
- set_page_private(data_page, (unsigned long)NULL);
- ClearPagePrivate(data_page);
- unlock_page(data_page);
- ext4_release_crypto_ctx(ctx);
-}
-
-/**
- * ext4_crypt_complete() - The completion callback for page encryption
- * @req: The asynchronous encryption request context
- * @res: The result of the encryption operation
- */
-static void ext4_crypt_complete(struct crypto_async_request *req, int res)
-{
- struct ext4_completion_result *ecr = req->data;
-
- if (res == -EINPROGRESS)
- return;
- ecr->res = res;
- complete(&ecr->completion);
-}
-
-typedef enum {
- EXT4_DECRYPT = 0,
- EXT4_ENCRYPT,
-} ext4_direction_t;
-
-static int ext4_page_crypto(struct inode *inode,
- ext4_direction_t rw,
- pgoff_t index,
- struct page *src_page,
- struct page *dest_page,
- gfp_t gfp_flags)
-
-{
- u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
- struct skcipher_request *req = NULL;
- DECLARE_EXT4_COMPLETION_RESULT(ecr);
- struct scatterlist dst, src;
- struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
- struct crypto_skcipher *tfm = ci->ci_ctfm;
- int res = 0;
-
- req = skcipher_request_alloc(tfm, gfp_flags);
- if (!req) {
- printk_ratelimited(KERN_ERR
- "%s: crypto_request_alloc() failed\n",
- __func__);
- return -ENOMEM;
- }
- skcipher_request_set_callback(
- req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
- ext4_crypt_complete, &ecr);
-
- BUILD_BUG_ON(EXT4_XTS_TWEAK_SIZE < sizeof(index));
- memcpy(xts_tweak, &index, sizeof(index));
- memset(&xts_tweak[sizeof(index)], 0,
- EXT4_XTS_TWEAK_SIZE - sizeof(index));
-
- sg_init_table(&dst, 1);
- sg_set_page(&dst, dest_page, PAGE_SIZE, 0);
- sg_init_table(&src, 1);
- sg_set_page(&src, src_page, PAGE_SIZE, 0);
- skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE,
- xts_tweak);
- if (rw == EXT4_DECRYPT)
- res = crypto_skcipher_decrypt(req);
- else
- res = crypto_skcipher_encrypt(req);
- if (res == -EINPROGRESS || res == -EBUSY) {
- wait_for_completion(&ecr.completion);
- res = ecr.res;
- }
- skcipher_request_free(req);
- if (res) {
- printk_ratelimited(
- KERN_ERR
- "%s: crypto_skcipher_encrypt() returned %d\n",
- __func__, res);
- return res;
- }
- return 0;
-}
-
-static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx,
- gfp_t gfp_flags)
-{
- ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, gfp_flags);
- if (ctx->w.bounce_page == NULL)
- return ERR_PTR(-ENOMEM);
- ctx->flags |= EXT4_WRITE_PATH_FL;
- return ctx->w.bounce_page;
-}
-
-/**
- * ext4_encrypt() - Encrypts a page
- * @inode: The inode for which the encryption should take place
- * @plaintext_page: The page to encrypt. Must be locked.
- *
- * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
- * encryption context.
- *
- * Called on the page write path. The caller must call
- * ext4_restore_control_page() on the returned ciphertext page to
- * release the bounce buffer and the encryption context.
- *
- * Return: An allocated page with the encrypted content on success. Else, an
- * error value or NULL.
- */
-struct page *ext4_encrypt(struct inode *inode,
- struct page *plaintext_page,
- gfp_t gfp_flags)
-{
- struct ext4_crypto_ctx *ctx;
- struct page *ciphertext_page = NULL;
- int err;
-
- BUG_ON(!PageLocked(plaintext_page));
-
- ctx = ext4_get_crypto_ctx(inode, gfp_flags);
- if (IS_ERR(ctx))
- return (struct page *) ctx;
-
- /* The encryption operation will require a bounce page. */
- ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
- if (IS_ERR(ciphertext_page))
- goto errout;
- ctx->w.control_page = plaintext_page;
- err = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index,
- plaintext_page, ciphertext_page, gfp_flags);
- if (err) {
- ciphertext_page = ERR_PTR(err);
- errout:
- ext4_release_crypto_ctx(ctx);
- return ciphertext_page;
- }
- SetPagePrivate(ciphertext_page);
- set_page_private(ciphertext_page, (unsigned long)ctx);
- lock_page(ciphertext_page);
- return ciphertext_page;
-}
-
-/**
- * ext4_decrypt() - Decrypts a page in-place
- * @ctx: The encryption context.
- * @page: The page to decrypt. Must be locked.
- *
- * Decrypts page in-place using the ctx encryption context.
- *
- * Called from the read completion callback.
- *
- * Return: Zero on success, non-zero otherwise.
- */
-int ext4_decrypt(struct page *page)
-{
- BUG_ON(!PageLocked(page));
-
- return ext4_page_crypto(page->mapping->host, EXT4_DECRYPT,
- page->index, page, page, GFP_NOFS);
-}
-
-int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk,
- ext4_fsblk_t pblk, ext4_lblk_t len)
-{
- struct ext4_crypto_ctx *ctx;
- struct page *ciphertext_page = NULL;
- struct bio *bio;
- int ret, err = 0;
-
-#if 0
- ext4_msg(inode->i_sb, KERN_CRIT,
- "ext4_encrypted_zeroout ino %lu lblk %u len %u",
- (unsigned long) inode->i_ino, lblk, len);
-#endif
-
- BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
-
- ctx = ext4_get_crypto_ctx(inode, GFP_NOFS);
- if (IS_ERR(ctx))
- return PTR_ERR(ctx);
-
- ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
- if (IS_ERR(ciphertext_page)) {
- err = PTR_ERR(ciphertext_page);
- goto errout;
- }
-
- while (len--) {
- err = ext4_page_crypto(inode, EXT4_ENCRYPT, lblk,
- ZERO_PAGE(0), ciphertext_page,
- GFP_NOFS);
- if (err)
- goto errout;
-
- bio = bio_alloc(GFP_NOWAIT, 1);
- if (!bio) {
- err = -ENOMEM;
- goto errout;
- }
- bio->bi_bdev = inode->i_sb->s_bdev;
- bio->bi_iter.bi_sector =
- pblk << (inode->i_sb->s_blocksize_bits - 9);
- ret = bio_add_page(bio, ciphertext_page,
- inode->i_sb->s_blocksize, 0);
- if (ret != inode->i_sb->s_blocksize) {
- /* should never happen! */
- ext4_msg(inode->i_sb, KERN_ERR,
- "bio_add_page failed: %d", ret);
- WARN_ON(1);
- bio_put(bio);
- err = -EIO;
- goto errout;
- }
- err = submit_bio_wait(WRITE, bio);
- if ((err == 0) && bio->bi_error)
- err = -EIO;
- bio_put(bio);
- if (err)
- goto errout;
- lblk++; pblk++;
- }
- err = 0;
-errout:
- ext4_release_crypto_ctx(ctx);
- return err;
-}
-
-bool ext4_valid_contents_enc_mode(uint32_t mode)
-{
- return (mode == EXT4_ENCRYPTION_MODE_AES_256_XTS);
-}
-
-/**
- * ext4_validate_encryption_key_size() - Validate the encryption key size
- * @mode: The key mode.
- * @size: The key size to validate.
- *
- * Return: The validated key size for @mode. Zero if invalid.
- */
-uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
-{
- if (size == ext4_encryption_key_size(mode))
- return size;
- return 0;
-}
-
-/*
- * Validate dentries for encrypted directories to make sure we aren't
- * potentially caching stale data after a key has been added or
- * removed.
- */
-static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
-{
- struct dentry *dir;
- struct ext4_crypt_info *ci;
- int dir_has_key, cached_with_key;
-
- if (flags & LOOKUP_RCU)
- return -ECHILD;
-
- dir = dget_parent(dentry);
- if (!ext4_encrypted_inode(d_inode(dir))) {
- dput(dir);
- return 0;
- }
- ci = EXT4_I(d_inode(dir))->i_crypt_info;
- if (ci && ci->ci_keyring_key &&
- (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
- (1 << KEY_FLAG_REVOKED) |
- (1 << KEY_FLAG_DEAD))))
- ci = NULL;
-
- /* this should eventually be an flag in d_flags */
- cached_with_key = dentry->d_fsdata != NULL;
- dir_has_key = (ci != NULL);
- dput(dir);
-
- /*
- * If the dentry was cached without the key, and it is a
- * negative dentry, it might be a valid name. We can't check
- * if the key has since been made available due to locking
- * reasons, so we fail the validation so ext4_lookup() can do
- * this check.
- *
- * We also fail the validation if the dentry was created with
- * the key present, but we no longer have the key, or vice versa.
- */
- if ((!cached_with_key && d_is_negative(dentry)) ||
- (!cached_with_key && dir_has_key) ||
- (cached_with_key && !dir_has_key)) {
-#if 0 /* Revalidation debug */
- char buf[80];
- char *cp = simple_dname(dentry, buf, sizeof(buf));
-
- if (IS_ERR(cp))
- cp = (char *) "???";
- pr_err("revalidate: %s %p %d %d %d\n", cp, dentry->d_fsdata,
- cached_with_key, d_is_negative(dentry),
- dir_has_key);
-#endif
- return 0;
- }
- return 1;
-}
-
-const struct dentry_operations ext4_encrypted_d_ops = {
- .d_revalidate = ext4_d_revalidate,
-};