ext4 crypto: add ext4 encryption facilities

On encrypt, we will re-assign the buffer_heads to point to a bounce
page rather than the control_page (which is the original page to write
that contains the plaintext). The block I/O occurs against the bounce
page.  On write completion, we re-assign the buffer_heads to the
original plaintext page.

On decrypt, we will attach a read completion callback to the bio
struct. This read completion will decrypt the read contents in-place
prior to setting the page up-to-date.

The current encryption mode, AES-256-XTS, lacks cryptographic
integrity. AES-256-GCM is in-plan, but we will need to devise a
mechanism for handling the integrity data.

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

6 files changed, 682 insertions, 1 deletions

diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 3886ee45f556..1b1c5619523d 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -12,4 +12,4 @@ ext4-y	:= balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
 
 ext4-$(CONFIG_EXT4_FS_POSIX_ACL)        += acl.o
 ext4-$(CONFIG_EXT4_FS_SECURITY)         += xattr_security.o
-ext4-$(CONFIG_EXT4_FS_ENCRYPTION)       += crypto_policy.o
+ext4-$(CONFIG_EXT4_FS_ENCRYPTION)       += crypto_policy.o crypto.o
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
new file mode 100644
index 000000000000..8ff15273ab0c
--- /dev/null
+++ b/fs/ext4/crypto.c
@@ -0,0 +1,558 @@
+/*
+ * 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/hash.h>
+#include <crypto/sha.h>
+#include <keys/user-type.h>
+#include <keys/encrypted-type.h>
+#include <linux/crypto.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 "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);
+
+/**
+ * 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->bounce_page) {
+                if (ctx->flags & EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL)
+                        __free_page(ctx->bounce_page);
+                else
+                        mempool_free(ctx->bounce_page, ext4_bounce_page_pool);
+                ctx->bounce_page = NULL;
+        }
+        ctx->control_page = NULL;
+        if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
+                if (ctx->tfm)
+                        crypto_free_tfm(ctx->tfm);
+                kfree(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_alloc_and_init_crypto_ctx() - Allocates and inits an encryption context
+ * @mask: The allocation mask.
+ *
+ * Return: An allocated and initialized encryption context on success. An error
+ * value or NULL otherwise.
+ */
+static struct ext4_crypto_ctx *ext4_alloc_and_init_crypto_ctx(gfp_t mask)
+{
+        struct ext4_crypto_ctx *ctx = kzalloc(sizeof(struct ext4_crypto_ctx),
+                                              mask);
+
+        if (!ctx)
+                return ERR_PTR(-ENOMEM);
+        return ctx;
+}
+
+/**
+ * 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)
+{
+        struct ext4_crypto_ctx *ctx = NULL;
+        int res = 0;
+        unsigned long flags;
+        struct ext4_encryption_key *key = &EXT4_I(inode)->i_encryption_key;
+
+        if (!ext4_read_workqueue)
+                ext4_init_crypto();
+
+        /*
+         * 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 = ext4_alloc_and_init_crypto_ctx(GFP_NOFS);
+                if (IS_ERR(ctx)) {
+                        res = PTR_ERR(ctx);
+                        goto out;
+                }
+                ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
+        } else {
+                ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
+        }
+
+        /* Allocate a new Crypto API context if we don't already have
+         * one or if it isn't the right mode. */
+        BUG_ON(key->mode == EXT4_ENCRYPTION_MODE_INVALID);
+        if (ctx->tfm && (ctx->mode != key->mode)) {
+                crypto_free_tfm(ctx->tfm);
+                ctx->tfm = NULL;
+                ctx->mode = EXT4_ENCRYPTION_MODE_INVALID;
+        }
+        if (!ctx->tfm) {
+                switch (key->mode) {
+                case EXT4_ENCRYPTION_MODE_AES_256_XTS:
+                        ctx->tfm = crypto_ablkcipher_tfm(
+                                crypto_alloc_ablkcipher("xts(aes)", 0, 0));
+                        break;
+                case EXT4_ENCRYPTION_MODE_AES_256_GCM:
+                        /* TODO(mhalcrow): AEAD w/ gcm(aes);
+                         * crypto_aead_setauthsize() */
+                        ctx->tfm = ERR_PTR(-ENOTSUPP);
+                        break;
+                default:
+                        BUG();
+                }
+                if (IS_ERR_OR_NULL(ctx->tfm)) {
+                        res = PTR_ERR(ctx->tfm);
+                        ctx->tfm = NULL;
+                        goto out;
+                }
+                ctx->mode = key->mode;
+        }
+        BUG_ON(key->size != ext4_encryption_key_size(key->mode));
+
+        /* There shouldn't be a bounce page attached to the crypto
+         * context at this point. */
+        BUG_ON(ctx->bounce_page);
+
+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) {
+                if (pos->bounce_page) {
+                        if (pos->flags &
+                            EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL) {
+                                __free_page(pos->bounce_page);
+                        } else {
+                                mempool_free(pos->bounce_page,
+                                             ext4_bounce_page_pool);
+                        }
+                }
+                if (pos->tfm)
+                        crypto_free_tfm(pos->tfm);
+                kfree(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;
+}
+
+/**
+ * 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;
+
+        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) {
+                res = -ENOMEM;
+                goto fail;
+        }
+
+        for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
+                struct ext4_crypto_ctx *ctx;
+
+                ctx = ext4_alloc_and_init_crypto_ctx(GFP_KERNEL);
+                if (IS_ERR(ctx)) {
+                        res = PTR_ERR(ctx);
+                        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 ext4_crypto_ctx *ctx,
+                            struct inode *inode,
+                            ext4_direction_t rw,
+                            pgoff_t index,
+                            struct page *src_page,
+                            struct page *dest_page)
+
+{
+        u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
+        struct ablkcipher_request *req = NULL;
+        DECLARE_EXT4_COMPLETION_RESULT(ecr);
+        struct scatterlist dst, src;
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        struct crypto_ablkcipher *atfm = __crypto_ablkcipher_cast(ctx->tfm);
+        int res = 0;
+
+        BUG_ON(!ctx->tfm);
+        BUG_ON(ctx->mode != ei->i_encryption_key.mode);
+
+        if (ctx->mode != EXT4_ENCRYPTION_MODE_AES_256_XTS) {
+                printk_ratelimited(KERN_ERR
+                                   "%s: unsupported crypto algorithm: %d\n",
+                                   __func__, ctx->mode);
+                return -ENOTSUPP;
+        }
+
+        crypto_ablkcipher_clear_flags(atfm, ~0);
+        crypto_tfm_set_flags(ctx->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
+
+        res = crypto_ablkcipher_setkey(atfm, ei->i_encryption_key.raw,
+                                       ei->i_encryption_key.size);
+        if (res) {
+                printk_ratelimited(KERN_ERR
+                                   "%s: crypto_ablkcipher_setkey() failed\n",
+                                   __func__);
+                return res;
+        }
+        req = ablkcipher_request_alloc(atfm, GFP_NOFS);
+        if (!req) {
+                printk_ratelimited(KERN_ERR
+                                   "%s: crypto_request_alloc() failed\n",
+                                   __func__);
+                return -ENOMEM;
+        }
+        ablkcipher_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_CACHE_SIZE, 0);
+        sg_init_table(&src, 1);
+        sg_set_page(&src, src_page, PAGE_CACHE_SIZE, 0);
+        ablkcipher_request_set_crypt(req, &src, &dst, PAGE_CACHE_SIZE,
+                                     xts_tweak);
+        if (rw == EXT4_DECRYPT)
+                res = crypto_ablkcipher_decrypt(req);
+        else
+                res = crypto_ablkcipher_encrypt(req);
+        if (res == -EINPROGRESS || res == -EBUSY) {
+                BUG_ON(req->base.data != &ecr);
+                wait_for_completion(&ecr.completion);
+                res = ecr.res;
+        }
+        ablkcipher_request_free(req);
+        if (res) {
+                printk_ratelimited(
+                        KERN_ERR
+                        "%s: crypto_ablkcipher_encrypt() returned %d\n",
+                        __func__, res);
+                return res;
+        }
+        return 0;
+}
+
+/**
+ * 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)
+{
+        struct ext4_crypto_ctx *ctx;
+        struct page *ciphertext_page = NULL;
+        int err;
+
+        BUG_ON(!PageLocked(plaintext_page));
+
+        ctx = ext4_get_crypto_ctx(inode);
+        if (IS_ERR(ctx))
+                return (struct page *) ctx;
+
+        /* The encryption operation will require a bounce page. */
+        ciphertext_page = alloc_page(GFP_NOFS);
+        if (!ciphertext_page) {
+                /* This is a potential bottleneck, but at least we'll have
+                 * forward progress. */
+                ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
+                                                 GFP_NOFS);
+                if (WARN_ON_ONCE(!ciphertext_page)) {
+                        ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
+                                                         GFP_NOFS | __GFP_WAIT);
+                }
+                ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
+        } else {
+                ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
+        }
+        ctx->bounce_page = ciphertext_page;
+        ctx->control_page = plaintext_page;
+        err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, plaintext_page->index,
+                               plaintext_page, ciphertext_page);
+        if (err) {
+                ext4_release_crypto_ctx(ctx);
+                return ERR_PTR(err);
+        }
+        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 ext4_crypto_ctx *ctx, struct page *page)
+{
+        BUG_ON(!PageLocked(page));
+
+        return ext4_page_crypto(ctx, page->mapping->host,
+                                EXT4_DECRYPT, page->index, page, page);
+}
+
+/*
+ * Convenience function which takes care of allocating and
+ * deallocating the encryption context
+ */
+int ext4_decrypt_one(struct inode *inode, struct page *page)
+{
+        int ret;
+
+        struct ext4_crypto_ctx *ctx = ext4_get_crypto_ctx(inode);
+
+        if (!ctx)
+                return -ENOMEM;
+        ret = ext4_decrypt(ctx, page);
+        ext4_release_crypto_ctx(ctx);
+        return ret;
+}
+
+int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
+{
+        struct ext4_crypto_ctx  *ctx;
+        struct page             *ciphertext_page = NULL;
+        struct bio              *bio;
+        ext4_lblk_t             lblk = ex->ee_block;
+        ext4_fsblk_t            pblk = ext4_ext_pblock(ex);
+        unsigned int            len = ext4_ext_get_actual_len(ex);
+        int                     err = 0;
+
+        BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE);
+
+        ctx = ext4_get_crypto_ctx(inode);
+        if (IS_ERR(ctx))
+                return PTR_ERR(ctx);
+
+        ciphertext_page = alloc_page(GFP_NOFS);
+        if (!ciphertext_page) {
+                /* This is a potential bottleneck, but at least we'll have
+                 * forward progress. */
+                ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
+                                                 GFP_NOFS);
+                if (WARN_ON_ONCE(!ciphertext_page)) {
+                        ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
+                                                         GFP_NOFS | __GFP_WAIT);
+                }
+                ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
+        } else {
+                ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
+        }
+        ctx->bounce_page = ciphertext_page;
+
+        while (len--) {
+                err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, lblk,
+                                       ZERO_PAGE(0), ciphertext_page);
+                if (err)
+                        goto errout;
+
+                bio = bio_alloc(GFP_KERNEL, 1);
+                if (!bio) {
+                        err = -ENOMEM;
+                        goto errout;
+                }
+                bio->bi_bdev = inode->i_sb->s_bdev;
+                bio->bi_iter.bi_sector = pblk;
+                err = bio_add_page(bio, ciphertext_page,
+                                   inode->i_sb->s_blocksize, 0);
+                if (err) {
+                        bio_put(bio);
+                        goto errout;
+                }
+                err = submit_bio_wait(WRITE, bio);
+                if (err)
+                        goto errout;
+        }
+        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;
+}
diff --git a/fs/ext4/crypto_policy.c b/fs/ext4/crypto_policy.c
index 532b69c0afab..a4bf762b3ba9 100644
--- a/fs/ext4/crypto_policy.c
+++ b/fs/ext4/crypto_policy.c
@@ -52,6 +52,13 @@ static int ext4_create_encryption_context_from_policy(
         ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
         memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
                EXT4_KEY_DESCRIPTOR_SIZE);
+        if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) {
+                printk(KERN_WARNING
+                       "%s: Invalid contents encryption mode %d\n", __func__,
+                        policy->contents_encryption_mode);
+                res = -EINVAL;
+                goto out;
+        }
         ctx.contents_encryption_mode = policy->contents_encryption_mode;
         ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
         BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
@@ -60,6 +67,7 @@ static int ext4_create_encryption_context_from_policy(
         res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
                              EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
                              sizeof(ctx), 0);
+out:
         if (!res)
                 ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
         return res;
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ab873aa9955e..71619ef72225 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -951,6 +951,11 @@ struct ext4_inode_info {
 
         /* Precomputed uuid+inum+igen checksum for seeding inode checksums */
         __u32 i_csum_seed;
+
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        /* Encryption params */
+        struct ext4_encryption_key i_encryption_key;
+#endif
 };
 
 /*
@@ -1366,6 +1371,12 @@ struct ext4_sb_info {
         struct ratelimit_state s_err_ratelimit_state;
         struct ratelimit_state s_warning_ratelimit_state;
         struct ratelimit_state s_msg_ratelimit_state;
+
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        /* Encryption */
+        uint32_t s_file_encryption_mode;
+        uint32_t s_dir_encryption_mode;
+#endif
 };
 
 static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
@@ -1481,6 +1492,18 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
 #define EXT4_SB(sb)     (sb)
 #endif
 
+/*
+ * Returns true if the inode is inode is encrypted
+ */
+static inline int ext4_encrypted_inode(struct inode *inode)
+{
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        return ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT);
+#else
+        return 0;
+#endif
+}
+
 #define NEXT_ORPHAN(inode) EXT4_I(inode)->i_dtime
 
 /*
@@ -2026,6 +2049,35 @@ int ext4_process_policy(const struct ext4_encryption_policy *policy,
 int ext4_get_policy(struct inode *inode,
                     struct ext4_encryption_policy *policy);
 
+/* crypto.c */
+bool ext4_valid_contents_enc_mode(uint32_t mode);
+uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size);
+extern struct workqueue_struct *ext4_read_workqueue;
+struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode);
+void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx);
+void ext4_restore_control_page(struct page *data_page);
+struct page *ext4_encrypt(struct inode *inode,
+                          struct page *plaintext_page);
+int ext4_decrypt(struct ext4_crypto_ctx *ctx, struct page *page);
+int ext4_decrypt_one(struct inode *inode, struct page *page);
+int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex);
+
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+int ext4_init_crypto(void);
+void ext4_exit_crypto(void);
+static inline int ext4_sb_has_crypto(struct super_block *sb)
+{
+        return EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_ENCRYPT);
+}
+#else
+static inline int ext4_init_crypto(void) { return 0; }
+static inline void ext4_exit_crypto(void) { }
+static inline int ext4_sb_has_crypto(struct super_block *sb)
+{
+        return 0;
+}
+#endif
+
 /* dir.c */
 extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
                                   struct file *,
diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h
index a69d2ba54bee..9d5d2e56cc46 100644
--- a/fs/ext4/ext4_crypto.h
+++ b/fs/ext4/ext4_crypto.h
@@ -46,4 +46,59 @@ struct ext4_encryption_context {
         char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE];
 } __attribute__((__packed__));
 
+/* Encryption parameters */
+#define EXT4_XTS_TWEAK_SIZE 16
+#define EXT4_AES_128_ECB_KEY_SIZE 16
+#define EXT4_AES_256_GCM_KEY_SIZE 32
+#define EXT4_AES_256_CBC_KEY_SIZE 32
+#define EXT4_AES_256_CTS_KEY_SIZE 32
+#define EXT4_AES_256_XTS_KEY_SIZE 64
+#define EXT4_MAX_KEY_SIZE 64
+
+struct ext4_encryption_key {
+        uint32_t mode;
+        char raw[EXT4_MAX_KEY_SIZE];
+        uint32_t size;
+};
+
+#define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL             0x00000001
+#define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL     0x00000002
+
+struct ext4_crypto_ctx {
+        struct crypto_tfm *tfm;         /* Crypto API context */
+        struct page *bounce_page;       /* Ciphertext page on write path */
+        struct page *control_page;      /* Original page on write path */
+        struct bio *bio;                /* The bio for this context */
+        struct work_struct work;        /* Work queue for read complete path */
+        struct list_head free_list;     /* Free list */
+        int flags;                      /* Flags */
+        int mode;                       /* Encryption mode for tfm */
+};
+
+struct ext4_completion_result {
+        struct completion completion;
+        int res;
+};
+
+#define DECLARE_EXT4_COMPLETION_RESULT(ecr) \
+        struct ext4_completion_result ecr = { \
+                COMPLETION_INITIALIZER((ecr).completion), 0 }
+
+static inline int ext4_encryption_key_size(int mode)
+{
+        switch (mode) {
+        case EXT4_ENCRYPTION_MODE_AES_256_XTS:
+                return EXT4_AES_256_XTS_KEY_SIZE;
+        case EXT4_ENCRYPTION_MODE_AES_256_GCM:
+                return EXT4_AES_256_GCM_KEY_SIZE;
+        case EXT4_ENCRYPTION_MODE_AES_256_CBC:
+                return EXT4_AES_256_CBC_KEY_SIZE;
+        case EXT4_ENCRYPTION_MODE_AES_256_CTS:
+                return EXT4_AES_256_CTS_KEY_SIZE;
+        default:
+                BUG();
+        }
+        return 0;
+}
+
 #endif  /* _EXT4_CRYPTO_H */
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e47a552fea05..1008ca258de4 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -876,6 +876,9 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
         atomic_set(&ei->i_ioend_count, 0);
         atomic_set(&ei->i_unwritten, 0);
         INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        ei->i_encryption_key.mode = EXT4_ENCRYPTION_MODE_INVALID;
+#endif
 
         return &ei->vfs_inode;
 }
@@ -3431,6 +3434,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
         if (sb->s_bdev->bd_part)
                 sbi->s_sectors_written_start =
                         part_stat_read(sb->s_bdev->bd_part, sectors[1]);
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        /* Modes of operations for file and directory encryption. */
+        sbi->s_file_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+        sbi->s_dir_encryption_mode = EXT4_ENCRYPTION_MODE_INVALID;
+#endif
 
         /* Cleanup superblock name */
         for (cp = sb->s_id; (cp = strchr(cp, '/'));)