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[PATCH 00/10 v2] File-level Encryption Support by VFS

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Contents

  [PATCH 00/10 v2] File-level Encryption Support by VFS Jaegeuk Kim <jaegeuk@kernel.org> - 2016-02-25 20:30 +0100
    [PATCH 05/10] fs crypto: add fname.c to support filename encryption Jaegeuk Kim <jaegeuk@kernel.org> - 2016-02-25 20:30 +0100
    [PATCH 03/10] fs crypto: add policy.c to handle contexts Jaegeuk Kim <jaegeuk@kernel.org> - 2016-02-25 20:30 +0100
    [PATCH 07/10] fs crypto: add dentry revalidation facility in crypto Jaegeuk Kim <jaegeuk@kernel.org> - 2016-02-25 20:30 +0100
    [PATCH 02/10] fs crypto: add crypto.c for encrypt/decrypt functions Jaegeuk Kim <jaegeuk@kernel.org> - 2016-02-25 20:30 +0100

#1343421 — [PATCH 00/10 v2] File-level Encryption Support by VFS

This patch series migrates the existing ext4 and f2fs per-file encryption
feature into VFS layer.

Due to the upcoming merge window, let me consider the following schedule.
1. migrate f2fs and there-in crypto codes into VFS during the next merge window
2. settle down new crypto lib in VFS during rc series
3. review, test, and migrate EXT4 changes accordingly

Change log from v1:
 o Adjust recent ext4 crypto patches

Jaegeuk Kim (10):
  fs crypto: add basic definitions for per-file encryption
  fs crypto: add crypto.c for encrypt/decrypt functions
  fs crypto: add policy.c to handle contexts
  fs crypto: add keyinfo.c to handle permissions
  fs crypto: add fname.c to support filename encryption
  fs crypto: add Makefile and Kconfig
  fs crypto: add dentry revalidation facility in crypto
  f2fs crypto: migrate into vfs's crypto engine
  f2fs crypto: sync ext4_lookup and ext4_file_open
  ext4 crypto: migrate into vfs's crypto engine

 fs/Kconfig               |   2 +
 fs/Makefile              |   1 +
 fs/crypto/Kconfig        |  17 ++
 fs/crypto/Makefile       |   2 +
 fs/crypto/crypto.c       | 554 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/crypto/fname.c        | 437 +++++++++++++++++++++++++++++++++++++
 fs/crypto/keyinfo.c      | 278 ++++++++++++++++++++++++
 fs/crypto/policy.c       | 229 ++++++++++++++++++++
 fs/ext4/Kconfig          |  12 +-
 fs/ext4/Makefile         |   2 -
 fs/ext4/crypto.c         | 525 --------------------------------------------
 fs/ext4/crypto_fname.c   | 470 ----------------------------------------
 fs/ext4/crypto_key.c     | 276 -----------------------
 fs/ext4/crypto_policy.c  | 229 --------------------
 fs/ext4/dir.c            |  28 +--
 fs/ext4/ext4.h           | 172 ++++-----------
 fs/ext4/ext4_crypto.h    | 159 --------------
 fs/ext4/file.c           |  10 +-
 fs/ext4/ialloc.c         |   7 +-
 fs/ext4/inline.c         |  14 +-
 fs/ext4/inode.c          |   8 +-
 fs/ext4/ioctl.c          |  20 +-
 fs/ext4/namei.c          | 120 +++++-----
 fs/ext4/page-io.c        |  13 +-
 fs/ext4/readpage.c       |  45 +---
 fs/ext4/super.c          |  85 +++++++-
 fs/ext4/symlink.c        |  33 ++-
 fs/f2fs/Kconfig          |  10 +-
 fs/f2fs/Makefile         |   2 -
 fs/f2fs/crypto.c         | 473 ----------------------------------------
 fs/f2fs/crypto_fname.c   | 446 --------------------------------------
 fs/f2fs/crypto_key.c     | 267 -----------------------
 fs/f2fs/crypto_policy.c  | 210 ------------------
 fs/f2fs/data.c           |  31 ++-
 fs/f2fs/dir.c            |  46 ++--
 fs/f2fs/f2fs.h           | 151 +------------
 fs/f2fs/f2fs_crypto.h    | 151 -------------
 fs/f2fs/file.c           |  40 ++--
 fs/f2fs/inline.c         |   4 +-
 fs/f2fs/inode.c          |   5 +-
 fs/f2fs/namei.c          |  79 ++++---
 fs/f2fs/super.c          |  55 +++--
 include/linux/dcache.h   |   2 +
 include/linux/fs.h       |   8 +
 include/linux/fscrypto.h | 383 ++++++++++++++++++++++++++++++++
 include/uapi/linux/fs.h  |  18 ++
 46 files changed, 2334 insertions(+), 3795 deletions(-)
 create mode 100644 fs/crypto/Kconfig
 create mode 100644 fs/crypto/Makefile
 create mode 100644 fs/crypto/crypto.c
 create mode 100644 fs/crypto/fname.c
 create mode 100644 fs/crypto/keyinfo.c
 create mode 100644 fs/crypto/policy.c
 delete mode 100644 fs/ext4/crypto.c
 delete mode 100644 fs/ext4/crypto_fname.c
 delete mode 100644 fs/ext4/crypto_key.c
 delete mode 100644 fs/ext4/crypto_policy.c
 delete mode 100644 fs/ext4/ext4_crypto.h
 delete mode 100644 fs/f2fs/crypto.c
 delete mode 100644 fs/f2fs/crypto_fname.c
 delete mode 100644 fs/f2fs/crypto_key.c
 delete mode 100644 fs/f2fs/crypto_policy.c
 delete mode 100644 fs/f2fs/f2fs_crypto.h
 create mode 100644 include/linux/fscrypto.h

-- 
2.6.3

[toc] | [next] | [standalone]

#1343423 — [PATCH 05/10] fs crypto: add fname.c to support filename encryption

This patch adds fname.c supporting filename encryption.

1. general wrapper functions
 - fscrypt_fname_disk_to_usr
 - fscrypt_fname_usr_to_disk
 - fscrypt_setup_filename
 - fscrypt_free_filename

2. specific filename handling functions
 - fscrypt_fname_alloc_buffer
 - fscrypt_fname_free_buffer

Signed-off-by: Uday Savagaonkar <savagaon@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/crypto/fname.c        | 437 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fscrypto.h |  13 ++
 2 files changed, 450 insertions(+)
 create mode 100644 fs/crypto/fname.c

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
new file mode 100644
index 0000000..8488a96
--- /dev/null
+++ b/fs/crypto/fname.c
@@ -0,0 +1,437 @@
+/*
+ * This contains functions for filename crypto management
+ *
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility
+ *
+ * Written by Uday Savagaonkar, 2014.
+ * Modified by Jaegeuk Kim, 2015.
+ *
+ * This has not yet undergone a rigorous security audit.
+ */
+
+#include <crypto/hash.h>
+#include <crypto/sha.h>
+#include <keys/encrypted-type.h>
+#include <keys/user-type.h>
+#include <linux/crypto.h>
+#include <linux/scatterlist.h>
+#include <linux/ratelimit.h>
+#include <linux/fscrypto.h>
+
+static u32 size_round_up(size_t size, size_t blksize)
+{
+	return ((size + blksize - 1) / blksize) * blksize;
+}
+
+#ifdef CONFIG_FS_ENCRYPTION
+/**
+ * dir_crypt_complete() -
+ */
+static void dir_crypt_complete(struct crypto_async_request *req, int res)
+{
+	struct fscrypt_completion_result *ecr = req->data;
+
+	if (res == -EINPROGRESS)
+		return;
+	ecr->res = res;
+	complete(&ecr->completion);
+}
+
+/**
+ * fname_encrypt() -
+ *
+ * This function encrypts the input filename, and returns the length of the
+ * ciphertext. Errors are returned as negative numbers.  We trust the caller to
+ * allocate sufficient memory to oname string.
+ */
+static int fname_encrypt(struct inode *inode,
+			const struct qstr *iname, struct fscrypt_str *oname)
+{
+	u32 ciphertext_len;
+	struct ablkcipher_request *req = NULL;
+	DECLARE_FS_COMPLETION_RESULT(ecr);
+	struct fscrypt_info *ci = inode->i_crypt_info;
+	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
+	int res = 0;
+	char iv[FS_CRYPTO_BLOCK_SIZE];
+	struct scatterlist src_sg, dst_sg;
+	int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
+	char *workbuf, buf[32], *alloc_buf = NULL;
+	unsigned lim;
+
+	lim = inode->i_sb->s_cop->max_namelen(inode);
+	if (iname->len <= 0 || iname->len > lim)
+		return -EIO;
+
+	ciphertext_len = (iname->len < FS_CRYPTO_BLOCK_SIZE) ?
+					FS_CRYPTO_BLOCK_SIZE : iname->len;
+	ciphertext_len = size_round_up(ciphertext_len, padding);
+	ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
+
+	if (ciphertext_len <= sizeof(buf)) {
+		workbuf = buf;
+	} else {
+		alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
+		if (!alloc_buf)
+			return -ENOMEM;
+		workbuf = alloc_buf;
+	}
+
+	/* Allocate request */
+	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
+	if (!req) {
+		printk_ratelimited(KERN_ERR
+			"%s: crypto_request_alloc() failed\n", __func__);
+		kfree(alloc_buf);
+		return -ENOMEM;
+	}
+	ablkcipher_request_set_callback(req,
+			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+			dir_crypt_complete, &ecr);
+
+	/* Copy the input */
+	memcpy(workbuf, iname->name, iname->len);
+	if (iname->len < ciphertext_len)
+		memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
+
+	/* Initialize IV */
+	memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
+
+	/* Create encryption request */
+	sg_init_one(&src_sg, workbuf, ciphertext_len);
+	sg_init_one(&dst_sg, oname->name, ciphertext_len);
+	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
+	res = crypto_ablkcipher_encrypt(req);
+	if (res == -EINPROGRESS || res == -EBUSY) {
+		wait_for_completion(&ecr.completion);
+		res = ecr.res;
+	}
+	kfree(alloc_buf);
+	ablkcipher_request_free(req);
+	if (res < 0)
+		printk_ratelimited(KERN_ERR
+				"%s: Error (error code %d)\n", __func__, res);
+
+	oname->len = ciphertext_len;
+	return res;
+}
+
+/*
+ * fname_decrypt()
+ *	This function decrypts the input filename, and returns
+ *	the length of the plaintext.
+ *	Errors are returned as negative numbers.
+ *	We trust the caller to allocate sufficient memory to oname string.
+ */
+static int fname_decrypt(struct inode *inode,
+				const struct fscrypt_str *iname,
+				struct fscrypt_str *oname)
+{
+	struct ablkcipher_request *req = NULL;
+	DECLARE_FS_COMPLETION_RESULT(ecr);
+	struct scatterlist src_sg, dst_sg;
+	struct fscrypt_info *ci = inode->i_crypt_info;
+	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
+	int res = 0;
+	char iv[FS_CRYPTO_BLOCK_SIZE];
+	unsigned lim;
+
+	lim = inode->i_sb->s_cop->max_namelen(inode);
+	if (iname->len <= 0 || iname->len > lim)
+		return -EIO;
+
+	/* Allocate request */
+	req = ablkcipher_request_alloc(tfm, 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,
+		dir_crypt_complete, &ecr);
+
+	/* Initialize IV */
+	memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
+
+	/* Create decryption request */
+	sg_init_one(&src_sg, iname->name, iname->len);
+	sg_init_one(&dst_sg, oname->name, oname->len);
+	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
+	res = crypto_ablkcipher_decrypt(req);
+	if (res == -EINPROGRESS || res == -EBUSY) {
+		wait_for_completion(&ecr.completion);
+		res = ecr.res;
+	}
+	ablkcipher_request_free(req);
+	if (res < 0) {
+		printk_ratelimited(KERN_ERR
+				"%s: Error (error code %d)\n", __func__, res);
+		return res;
+	}
+
+	oname->len = strnlen(oname->name, iname->len);
+	return oname->len;
+}
+#endif
+
+static const char *lookup_table =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
+
+/**
+ * digest_encode() -
+ *
+ * Encodes the input digest using characters from the set [a-zA-Z0-9_+].
+ * The encoded string is roughly 4/3 times the size of the input string.
+ */
+static int digest_encode(const char *src, int len, char *dst)
+{
+	int i = 0, bits = 0, ac = 0;
+	char *cp = dst;
+
+	while (i < len) {
+		ac += (((unsigned char) src[i]) << bits);
+		bits += 8;
+		do {
+			*cp++ = lookup_table[ac & 0x3f];
+			ac >>= 6;
+			bits -= 6;
+		} while (bits >= 6);
+		i++;
+	}
+	if (bits)
+		*cp++ = lookup_table[ac & 0x3f];
+	return cp - dst;
+}
+
+static int digest_decode(const char *src, int len, char *dst)
+{
+	int i = 0, bits = 0, ac = 0;
+	const char *p;
+	char *cp = dst;
+
+	while (i < len) {
+		p = strchr(lookup_table, src[i]);
+		if (p == NULL || src[i] == 0)
+			return -2;
+		ac += (p - lookup_table) << bits;
+		bits += 6;
+		if (bits >= 8) {
+			*cp++ = ac & 0xff;
+			ac >>= 8;
+			bits -= 8;
+		}
+		i++;
+	}
+	if (ac)
+		return -1;
+	return cp - dst;
+}
+
+u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen)
+{
+	int padding = 32;
+#ifdef CONFIG_FS_ENCRYPTION
+	struct fscrypt_info *ci = inode->i_crypt_info;
+
+	if (ci)
+		padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
+#endif
+	if (ilen < FS_CRYPTO_BLOCK_SIZE)
+		ilen = FS_CRYPTO_BLOCK_SIZE;
+	return size_round_up(ilen, padding);
+}
+EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
+
+/**
+ * fscrypt_fname_crypto_alloc_obuff() -
+ *
+ * Allocates an output buffer that is sufficient for the crypto operation
+ * specified by the context and the direction.
+ */
+int fscrypt_fname_alloc_buffer(struct inode *inode,
+				u32 ilen, struct fscrypt_str *crypto_str)
+{
+	unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen);
+
+	crypto_str->len = olen;
+	if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2)
+		olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2;
+	/*
+	 * Allocated buffer can hold one more character to null-terminate the
+	 * string
+	 */
+	crypto_str->name = kmalloc(olen + 1, GFP_NOFS);
+	if (!(crypto_str->name))
+		return -ENOMEM;
+	return 0;
+}
+EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
+
+/**
+ * fscrypt_fname_crypto_free_buffer() -
+ *
+ * Frees the buffer allocated for crypto operation.
+ */
+void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
+{
+	if (!crypto_str)
+		return;
+	kfree(crypto_str->name);
+	crypto_str->name = NULL;
+}
+EXPORT_SYMBOL(fscrypt_fname_free_buffer);
+
+/**
+ * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user
+ * space
+ */
+int fscrypt_fname_disk_to_usr(struct inode *inode,
+			u32 hash, u32 minor_hash,
+			const struct fscrypt_str *iname,
+			struct fscrypt_str *oname)
+{
+	const struct qstr qname = FSTR_TO_QSTR(iname);
+	char buf[24];
+	int ret;
+
+	if (fscrypt_is_dot_dotdot(&qname)) {
+		oname->name[0] = '.';
+		oname->name[iname->len - 1] = '.';
+		oname->len = iname->len;
+		return oname->len;
+	}
+
+	if (iname->len < FS_CRYPTO_BLOCK_SIZE)
+		return -EUCLEAN;
+
+#ifdef CONFIG_FS_ENCRYPTION
+	if (inode->i_crypt_info)
+		return fname_decrypt(inode, iname, oname);
+#endif
+
+	if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) {
+		ret = digest_encode(iname->name, iname->len, oname->name);
+		oname->len = ret;
+		return ret;
+	}
+	if (hash) {
+		memcpy(buf, &hash, 4);
+		memcpy(buf + 4, &minor_hash, 4);
+	} else {
+		memset(buf, 0, 8);
+	}
+	memcpy(buf + 8, iname->name + iname->len - 16, 16);
+	oname->name[0] = '_';
+	ret = digest_encode(buf, 24, oname->name + 1);
+	oname->len = ret + 1;
+	return ret + 1;
+}
+EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
+
+/**
+ * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk
+ * space
+ */
+int fscrypt_fname_usr_to_disk(struct inode *inode,
+			const struct qstr *iname,
+			struct fscrypt_str *oname)
+{
+	if (fscrypt_is_dot_dotdot(iname)) {
+		oname->name[0] = '.';
+		oname->name[iname->len - 1] = '.';
+		oname->len = iname->len;
+		return oname->len;
+	}
+#ifdef CONFIG_FS_ENCRYPTION
+	if (inode->i_crypt_info)
+		return fname_encrypt(inode, iname, oname);
+#endif
+	/*
+	 * Without a proper key, a user is not allowed to modify the filenames
+	 * in a directory. Consequently, a user space name cannot be mapped to
+	 * a disk-space name
+	 */
+	return -EACCES;
+}
+EXPORT_SYMBOL(fscrypt_fname_usr_to_disk);
+
+int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
+			      int lookup, struct fscrypt_name *fname)
+{
+	int ret = 0, bigname = 0;
+
+	memset(fname, 0, sizeof(struct fscrypt_name));
+	fname->usr_fname = iname;
+
+	if (!dir->i_sb->s_cop->is_encrypted(dir) ||
+				fscrypt_is_dot_dotdot(iname)) {
+		fname->disk_name.name = (unsigned char *)iname->name;
+		fname->disk_name.len = iname->len;
+		return 0;
+	}
+	ret = get_crypt_info(dir);
+	if (ret && ret != -EOPNOTSUPP)
+		return ret;
+
+#ifdef CONFIG_FS_ENCRYPTION
+	if (dir->i_crypt_info) {
+		ret = fscrypt_fname_alloc_buffer(dir, iname->len,
+							&fname->crypto_buf);
+		if (ret < 0)
+			return ret;
+		ret = fname_encrypt(dir, iname, &fname->crypto_buf);
+		if (ret < 0)
+			goto errout;
+		fname->disk_name.name = fname->crypto_buf.name;
+		fname->disk_name.len = fname->crypto_buf.len;
+		return 0;
+	}
+#endif
+	if (!lookup)
+		return -EACCES;
+
+	/*
+	 * We don't have the key and we are doing a lookup; decode the
+	 * user-supplied name
+	 */
+	if (iname->name[0] == '_')
+		bigname = 1;
+	if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43)))
+		return -ENOENT;
+
+	fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
+	if (fname->crypto_buf.name == NULL)
+		return -ENOMEM;
+
+	ret = digest_decode(iname->name + bigname, iname->len - bigname,
+				fname->crypto_buf.name);
+	if (ret < 0) {
+		ret = -ENOENT;
+		goto errout;
+	}
+	fname->crypto_buf.len = ret;
+	if (bigname) {
+		memcpy(&fname->hash, fname->crypto_buf.name, 4);
+		memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4);
+	} else {
+		fname->disk_name.name = fname->crypto_buf.name;
+		fname->disk_name.len = fname->crypto_buf.len;
+	}
+	return 0;
+
+errout:
+	fscrypt_fname_free_buffer(&fname->crypto_buf);
+	return ret;
+}
+EXPORT_SYMBOL(fscrypt_setup_filename);
+
+void fscrypt_free_filename(struct fscrypt_name *fname)
+{
+	kfree(fname->crypto_buf.name);
+	fname->crypto_buf.name = NULL;
+	fname->usr_fname = NULL;
+	fname->disk_name.name = NULL;
+}
+EXPORT_SYMBOL(fscrypt_free_filename);
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index 2238a5e..3387da3 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -347,4 +347,17 @@ static inline void fscrypt_put_encryption_info(struct inode *i,
 	return;
 }
 #endif
+
+/* fname.c */
+int fscrypt_setup_filename(struct inode *, const struct qstr *,
+				int lookup, struct fscrypt_name *);
+void fscrypt_free_filename(struct fscrypt_name *);
+u32 fscrypt_fname_encrypted_size(struct inode *, u32);
+int fscrypt_fname_alloc_buffer(struct inode *, u32, struct fscrypt_str *);
+void fscrypt_fname_free_buffer(struct fscrypt_str *);
+int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
+			const struct fscrypt_str *, struct fscrypt_str *);
+int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
+			struct fscrypt_str *);
+
 #endif	/* _LINUX_FSCRYPTO_H */
-- 
2.6.3

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#1343424 — [PATCH 03/10] fs crypto: add policy.c to handle contexts

This patch adds policy.c supporting context management.

1. For ioctls:
 - fscrypt_process_policy
 - fscrypt_get_policy

2. For context permission
 - fscrypt_has_permitted_context
 - fscrypt_inherit_context

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Ildar Muslukhov <muslukhovi@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/crypto/policy.c       | 229 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fscrypto.h |  30 +++++++
 2 files changed, 259 insertions(+)
 create mode 100644 fs/crypto/policy.c

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
new file mode 100644
index 0000000..0f9961e
--- /dev/null
+++ b/fs/crypto/policy.c
@@ -0,0 +1,229 @@
+/*
+ * Encryption policy functions for per-file encryption support.
+ *
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility.
+ *
+ * Written by Michael Halcrow, 2015.
+ * Modified by Jaegeuk Kim, 2015.
+ */
+
+#include <linux/random.h>
+#include <linux/string.h>
+#include <linux/fscrypto.h>
+
+static int inode_has_encryption_context(struct inode *inode)
+{
+	if (!inode->i_sb->s_cop->get_context)
+		return 0;
+	return (inode->i_sb->s_cop->get_context(inode, NULL, 0L) > 0);
+}
+
+/*
+ * check whether the policy is consistent with the encryption context
+ * for the inode
+ */
+static int is_encryption_context_consistent_with_policy(struct inode *inode,
+				const struct fscrypt_policy *policy)
+{
+	struct fscrypt_context ctx;
+	int res;
+
+	if (!inode->i_sb->s_cop->get_context)
+		return 0;
+
+	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+	if (res != sizeof(ctx))
+		return 0;
+
+	return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
+			FS_KEY_DESCRIPTOR_SIZE) == 0 &&
+			(ctx.flags == policy->flags) &&
+			(ctx.contents_encryption_mode ==
+			 policy->contents_encryption_mode) &&
+			(ctx.filenames_encryption_mode ==
+			 policy->filenames_encryption_mode));
+}
+
+static int create_encryption_context_from_policy(struct inode *inode,
+				const struct fscrypt_policy *policy)
+{
+	struct fscrypt_context ctx;
+	int res;
+
+	if (!inode->i_sb->s_cop->set_context)
+		return -EOPNOTSUPP;
+
+	if (inode->i_sb->s_cop->prepare_context) {
+		res = inode->i_sb->s_cop->prepare_context(inode);
+		if (res)
+			return res;
+	}
+
+	ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
+	memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
+					FS_KEY_DESCRIPTOR_SIZE);
+
+	if (!fscrypt_valid_contents_enc_mode(
+				policy->contents_encryption_mode)) {
+		printk(KERN_WARNING
+		       "%s: Invalid contents encryption mode %d\n", __func__,
+			policy->contents_encryption_mode);
+		return -EINVAL;
+	}
+
+	if (!fscrypt_valid_filenames_enc_mode(
+				policy->filenames_encryption_mode)) {
+		printk(KERN_WARNING
+			"%s: Invalid filenames encryption mode %d\n", __func__,
+			policy->filenames_encryption_mode);
+		return -EINVAL;
+	}
+
+	if (policy->flags & ~FS_POLICY_FLAGS_VALID)
+		return -EINVAL;
+
+	ctx.contents_encryption_mode = policy->contents_encryption_mode;
+	ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
+	ctx.flags = policy->flags;
+	BUILD_BUG_ON(sizeof(ctx.nonce) != FS_KEY_DERIVATION_NONCE_SIZE);
+	get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
+
+	return inode->i_sb->s_cop->set_context(inode, &ctx, sizeof(ctx), NULL);
+}
+
+int fscrypt_process_policy(struct inode *inode,
+				const struct fscrypt_policy *policy)
+{
+	if (policy->version != 0)
+		return -EINVAL;
+
+	if (!inode_has_encryption_context(inode)) {
+		if (!inode->i_sb->s_cop->empty_dir)
+			return -EOPNOTSUPP;
+		if (!inode->i_sb->s_cop->empty_dir(inode))
+			return -ENOTEMPTY;
+		return create_encryption_context_from_policy(inode, policy);
+	}
+
+	if (is_encryption_context_consistent_with_policy(inode, policy))
+		return 0;
+
+	printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
+	       __func__);
+	return -EINVAL;
+}
+EXPORT_SYMBOL(fscrypt_process_policy);
+
+int fscrypt_get_policy(struct inode *inode, struct fscrypt_policy *policy)
+{
+	struct fscrypt_context ctx;
+	int res;
+
+	if (!inode->i_sb->s_cop->get_context ||
+			!inode->i_sb->s_cop->is_encrypted(inode))
+		return -ENODATA;
+
+	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+	if (res != sizeof(ctx))
+		return -ENODATA;
+	if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
+		return -EINVAL;
+
+	policy->version = 0;
+	policy->contents_encryption_mode = ctx.contents_encryption_mode;
+	policy->filenames_encryption_mode = ctx.filenames_encryption_mode;
+	policy->flags = ctx.flags;
+	memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor,
+				FS_KEY_DESCRIPTOR_SIZE);
+	return 0;
+}
+EXPORT_SYMBOL(fscrypt_get_policy);
+
+int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
+{
+	struct fscrypt_info *parent_ci, *child_ci;
+	int res;
+
+	if ((parent == NULL) || (child == NULL)) {
+		printk(KERN_ERR	"parent %p child %p\n", parent, child);
+		BUG_ON(1);
+	}
+
+	/* no restrictions if the parent directory is not encrypted */
+	if (!parent->i_sb->s_cop->is_encrypted(parent))
+		return 1;
+	/* if the child directory is not encrypted, this is always a problem */
+	if (!parent->i_sb->s_cop->is_encrypted(child))
+		return 0;
+	res = fscrypt_get_encryption_info(parent);
+	if (res)
+		return 0;
+	res = fscrypt_get_encryption_info(child);
+	if (res)
+		return 0;
+	parent_ci = parent->i_crypt_info;
+	child_ci = child->i_crypt_info;
+	if (!parent_ci && !child_ci)
+		return 1;
+	if (!parent_ci || !child_ci)
+		return 0;
+
+	return (memcmp(parent_ci->ci_master_key,
+			child_ci->ci_master_key,
+			FS_KEY_DESCRIPTOR_SIZE) == 0 &&
+		(parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
+		(parent_ci->ci_filename_mode == child_ci->ci_filename_mode) &&
+		(parent_ci->ci_flags == child_ci->ci_flags));
+}
+EXPORT_SYMBOL(fscrypt_has_permitted_context);
+
+/**
+ * fscrypt_inherit_context() - Sets a child context from its parent
+ * @parent: Parent inode from which the context is inherited.
+ * @child:  Child inode that inherits the context from @parent.
+ * @fs_data:  private data given by FS.
+ * @preload:  preload child i_crypt_info
+ *
+ * Return: Zero on success, non-zero otherwise
+ */
+int fscrypt_inherit_context(struct inode *parent, struct inode *child,
+						void *fs_data, bool preload)
+{
+	struct fscrypt_context ctx;
+	struct fscrypt_info *ci;
+	int res;
+
+	if (!parent->i_sb->s_cop->set_context)
+		return -EOPNOTSUPP;
+
+	res = fscrypt_get_encryption_info(parent);
+	if (res < 0)
+		return res;
+
+	ci = parent->i_crypt_info;
+	if (ci == NULL)
+		return -ENOKEY;
+
+	ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
+	if (fscrypt_dummy_context_enabled(parent)) {
+		ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS;
+		ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS;
+		ctx.flags = 0;
+		memset(ctx.master_key_descriptor, 0x42, FS_KEY_DESCRIPTOR_SIZE);
+		res = 0;
+	} else {
+		ctx.contents_encryption_mode = ci->ci_data_mode;
+		ctx.filenames_encryption_mode = ci->ci_filename_mode;
+		ctx.flags = ci->ci_flags;
+		memcpy(ctx.master_key_descriptor, ci->ci_master_key,
+				FS_KEY_DESCRIPTOR_SIZE);
+	}
+	get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
+	res = parent->i_sb->s_cop->set_context(child, &ctx,
+						sizeof(ctx), fs_data);
+	if (res)
+		return res;
+	return preload ? fscrypt_get_encryption_info(child): 0;
+}
+EXPORT_SYMBOL(fscrypt_inherit_context);
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index 09fbcfb..5b18b89 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -251,6 +251,12 @@ void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
 void fscrypt_pullback_bio_page(struct page **, bool);
 void fscrypt_restore_control_page(struct page *);
 int fscrypt_zeroout_range(struct inode *, pgoff_t, sector_t, unsigned int);
+
+/* policy.c */
+int fscrypt_process_policy(struct inode *, const struct fscrypt_policy *);
+int fscrypt_get_policy(struct inode *, struct fscrypt_policy *);
+int fscrypt_has_permitted_context(struct inode *, struct inode *);
+int fscrypt_inherit_context(struct inode *, struct inode *, void *, bool);
 #else
 /* crypto.c */
 static inline struct fscrypt_ctx *fscrypt_get_ctx(struct inode *i)
@@ -294,5 +300,29 @@ static inline int fscrypt_zeroout_range(struct inode *i, pgoff_t p,
 {
 	return -EOPNOTSUPP;
 }
+
+/* policy.c */
+static inline int fscrypt_process_policy(struct inode *i,
+				const struct fscrypt_policy *p)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int fscrypt_get_policy(struct inode *i, struct fscrypt_policy *p)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int fscrypt_has_permitted_context(struct inode *p,
+				struct inode *i)
+{
+	return 0;
+}
+
+static inline int fscrypt_inherit_context(struct inode *p, struct inode *i,
+				void *v, bool b)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 #endif	/* _LINUX_FSCRYPTO_H */
-- 
2.6.3

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#1343425 — [PATCH 07/10] fs crypto: add dentry revalidation facility in crypto

This patch is to support the following ext4 crypto change.

commit 28b4c263961c47da84ed8b5be0b5116bad1133eb
Author: Theodore Ts'o <tytso@mit.edu>
Date:   Sun Feb 7 19:35:05 2016 -0500

    ext4 crypto: revalidate dentry after adding or removing the key

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/crypto/crypto.c       | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dcache.h   |  2 ++
 include/linux/fscrypto.h | 20 ++++++++++++++++++++
 3 files changed, 71 insertions(+)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 2aa6eee..ed17895 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -27,6 +27,7 @@
 #include <linux/scatterlist.h>
 #include <linux/ratelimit.h>
 #include <linux/bio.h>
+#include <linux/dcache.h>
 #include <linux/fscrypto.h>
 
 static unsigned int num_prealloc_crypto_pages = 32;
@@ -339,6 +340,54 @@ errout:
 EXPORT_SYMBOL(fscrypt_zeroout_range);
 
 /*
+ * 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 fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct inode *dir = d_inode(dentry->d_parent);
+	struct fscrypt_info *ci = dir->i_crypt_info;
+	int dir_has_key, cached_with_key;
+
+	if (!dir->i_sb->s_cop->is_encrypted(dir))
+		return 0;
+
+	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 */
+	spin_lock(&dentry->d_lock);
+	cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
+	spin_unlock(&dentry->d_lock);
+	dir_has_key = (ci != NULL);
+
+	/*
+	 * 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))
+		return 0;
+	return 1;
+}
+
+const struct dentry_operations fscrypt_d_ops = {
+	.d_revalidate = fscrypt_d_revalidate,
+};
+EXPORT_SYMBOL(fscrypt_d_ops);
+
+/*
  * Call fscrypt_decrypt_page on every single page, reusing the encryption
  * context.
  */
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 7781ce11..c7bdfc5 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -228,6 +228,8 @@ struct dentry_operations {
 #define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
 #define DCACHE_OP_SELECT_INODE		0x02000000 /* Unioned entry: dcache op selects inode */
 
+#define DCACHE_ENCRYPTED_WITH_KEY	0x04000000 /* dir is encrypted with a valid key */
+
 extern seqlock_t rename_lock;
 
 /*
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index 3387da3..3a1fbb6 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -237,6 +237,26 @@ static inline int fscrypt_has_encryption_key(struct inode *inode)
 #endif
 }
 
+static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
+{
+#ifdef CONFIG_FS_ENCRYPTION
+	spin_lock(&dentry->d_lock);
+	dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
+	spin_unlock(&dentry->d_lock);
+#endif
+}
+
+#ifdef CONFIG_FS_ENCRYPTION
+extern const struct dentry_operations fscrypt_d_ops;
+#endif
+
+static inline void fscrypt_set_d_op(struct dentry *dentry)
+{
+#ifdef CONFIG_FS_ENCRYPTION
+	d_set_d_op(dentry, &fscrypt_d_ops);
+#endif
+}
+
 /* crypto.c */
 extern struct kmem_cache *fscrypt_info_cachep;
 int fscrypt_initialize(void);
-- 
2.6.3

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#1343426 — [PATCH 02/10] fs crypto: add crypto.c for encrypt/decrypt functions

This patch adds crypto.c supporting encrypting and decrypting functions.

1. IO preparation:
  - fscrypt_get_ctx / fscrypt_release_ctx

2. before IOs:
  - fscrypt_encrypt_page
  - fscrypt_decrypt_page
  - fscrypt_zeroout_range

3. after IOs:
  - fscrypt_decrypt_bio_pages
  - fscrypt_pullback_bio_page
  - fscrypt_restore_control_page

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>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/crypto/crypto.c       | 505 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fscrypto.h |  59 ++++++
 2 files changed, 564 insertions(+)
 create mode 100644 fs/crypto/crypto.c

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
new file mode 100644
index 0000000..2aa6eee
--- /dev/null
+++ b/fs/crypto/crypto.c
@@ -0,0 +1,505 @@
+/*
+ * 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/crypto.h>
+#include <linux/ecryptfs.h>
+#include <linux/pagemap.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/ratelimit.h>
+#include <linux/bio.h>
+#include <linux/fscrypto.h>
+
+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 *fscrypt_bounce_page_pool = NULL;
+
+static LIST_HEAD(fscrypt_free_ctxs);
+static DEFINE_SPINLOCK(fscrypt_ctx_lock);
+
+static struct workqueue_struct *fscrypt_read_workqueue;
+static DEFINE_MUTEX(fscrypt_init_mutex);
+
+static struct kmem_cache *fscrypt_ctx_cachep;
+struct kmem_cache *fscrypt_info_cachep;
+
+/**
+ * fscrypt_release_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 fscrypt_release_ctx(struct fscrypt_ctx *ctx)
+{
+	unsigned long flags;
+
+	if (ctx->flags & FS_WRITE_PATH_FL && ctx->w.bounce_page) {
+		mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool);
+		ctx->w.bounce_page = NULL;
+	}
+	ctx->w.control_page = NULL;
+	if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
+		kmem_cache_free(fscrypt_ctx_cachep, ctx);
+	} else {
+		spin_lock_irqsave(&fscrypt_ctx_lock, flags);
+		list_add(&ctx->free_list, &fscrypt_free_ctxs);
+		spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
+	}
+}
+EXPORT_SYMBOL(fscrypt_release_ctx);
+
+/**
+ * fscrypt_get_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 fscrypt_ctx *fscrypt_get_ctx(struct inode *inode)
+{
+	struct fscrypt_ctx *ctx = NULL;
+	struct fscrypt_info *ci = inode->i_crypt_info;
+	unsigned long flags;
+
+	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(&fscrypt_ctx_lock, flags);
+	ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
+					struct fscrypt_ctx, free_list);
+	if (ctx)
+		list_del(&ctx->free_list);
+	spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
+	if (!ctx) {
+		ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
+		if (!ctx)
+			return ERR_PTR(-ENOMEM);
+		ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
+	} else {
+		ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
+	}
+	ctx->flags &= ~FS_WRITE_PATH_FL;
+	return ctx;
+}
+EXPORT_SYMBOL(fscrypt_get_ctx);
+
+/**
+ * fscrypt_complete() - The completion callback for page encryption
+ * @req: The asynchronous encryption request context
+ * @res: The result of the encryption operation
+ */
+static void fscrypt_complete(struct crypto_async_request *req, int res)
+{
+	struct fscrypt_completion_result *ecr = req->data;
+
+	if (res == -EINPROGRESS)
+		return;
+	ecr->res = res;
+	complete(&ecr->completion);
+}
+
+typedef enum {
+	FS_DECRYPT = 0,
+	FS_ENCRYPT,
+} fscrypt_direction_t;
+
+static int do_page_crypto(struct inode *inode,
+			fscrypt_direction_t rw, pgoff_t index,
+			struct page *src_page, struct page *dest_page)
+{
+	u8 xts_tweak[FS_XTS_TWEAK_SIZE];
+	struct ablkcipher_request *req = NULL;
+	DECLARE_FS_COMPLETION_RESULT(ecr);
+	struct scatterlist dst, src;
+	struct fscrypt_info *ci = inode->i_crypt_info;
+	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
+	int res = 0;
+
+	req = ablkcipher_request_alloc(tfm, 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,
+		fscrypt_complete, &ecr);
+
+	BUILD_BUG_ON(FS_XTS_TWEAK_SIZE < sizeof(index));
+	memcpy(xts_tweak, &inode->i_ino, sizeof(index));
+	memset(&xts_tweak[sizeof(index)], 0,
+			FS_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 == FS_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;
+}
+
+static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
+{
+	ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool,
+							GFP_NOWAIT);
+	if (ctx->w.bounce_page == NULL)
+		return ERR_PTR(-ENOMEM);
+	ctx->flags |= FS_WRITE_PATH_FL;
+	return ctx->w.bounce_page;
+}
+
+/**
+ * fscypt_encrypt_page() - 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
+ * fscrypt_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 *fscrypt_encrypt_page(struct inode *inode,
+				struct page *plaintext_page)
+{
+	struct fscrypt_ctx *ctx;
+	struct page *ciphertext_page = NULL;
+	int err;
+
+	BUG_ON(!PageLocked(plaintext_page));
+
+	ctx = fscrypt_get_ctx(inode);
+	if (IS_ERR(ctx))
+		return (struct page *)ctx;
+
+	/* The encryption operation will require a bounce page. */
+	ciphertext_page = alloc_bounce_page(ctx);
+	if (IS_ERR(ciphertext_page))
+		goto errout;
+
+	ctx->w.control_page = plaintext_page;
+	err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
+					plaintext_page, ciphertext_page);
+	if (err) {
+		ciphertext_page = ERR_PTR(err);
+		goto errout;
+	}
+	SetPagePrivate(ciphertext_page);
+	set_page_private(ciphertext_page, (unsigned long)ctx);
+	lock_page(ciphertext_page);
+	return ciphertext_page;
+
+errout:
+	fscrypt_release_ctx(ctx);
+	return ciphertext_page;
+}
+EXPORT_SYMBOL(fscrypt_encrypt_page);
+
+/**
+ * f2crypt_decrypt_page() - Decrypts a page in-place
+ * @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 fscrypt_decrypt_page(struct page *page)
+{
+	BUG_ON(!PageLocked(page));
+
+	return do_page_crypto(page->mapping->host,
+			FS_DECRYPT, page->index, page, page);
+}
+EXPORT_SYMBOL(fscrypt_decrypt_page);
+
+int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
+				sector_t pblk, unsigned int len)
+{
+	struct fscrypt_ctx *ctx;
+	struct page *ciphertext_page = NULL;
+	struct bio *bio;
+	int ret, err = 0;
+
+	BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE);
+
+	ctx = fscrypt_get_ctx(inode);
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
+
+	ciphertext_page = alloc_bounce_page(ctx);
+	if (IS_ERR(ciphertext_page)) {
+		err = PTR_ERR(ciphertext_page);
+		goto errout;
+	}
+
+	while (len--) {
+		err = do_page_crypto(inode, FS_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 << (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! */
+			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:
+	fscrypt_release_ctx(ctx);
+	return err;
+}
+EXPORT_SYMBOL(fscrypt_zeroout_range);
+
+/*
+ * Call fscrypt_decrypt_page on every single page, reusing the encryption
+ * context.
+ */
+static void completion_pages(struct work_struct *work)
+{
+	struct fscrypt_ctx *ctx =
+		container_of(work, struct fscrypt_ctx, r.work);
+	struct bio *bio = ctx->r.bio;
+	struct bio_vec *bv;
+	int i;
+
+	bio_for_each_segment_all(bv, bio, i) {
+		struct page *page = bv->bv_page;
+		int ret = fscrypt_decrypt_page(page);
+
+		if (ret) {
+			WARN_ON_ONCE(1);
+			SetPageError(page);
+		} else {
+			SetPageUptodate(page);
+		}
+		unlock_page(page);
+	}
+	fscrypt_release_ctx(ctx);
+	bio_put(bio);
+}
+
+void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
+{
+	INIT_WORK(&ctx->r.work, completion_pages);
+	ctx->r.bio = bio;
+	queue_work(fscrypt_read_workqueue, &ctx->r.work);
+}
+EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
+
+void fscrypt_pullback_bio_page(struct page **page, bool restore)
+{
+	struct fscrypt_ctx *ctx;
+	struct page *bounce_page;
+
+	/* The bounce data pages are unmapped. */
+	if ((*page)->mapping)
+		return;
+
+	/* The bounce data page is unmapped. */
+	bounce_page = *page;
+	ctx = (struct fscrypt_ctx *)page_private(bounce_page);
+
+	/* restore control page */
+	*page = ctx->w.control_page;
+
+	if (restore)
+		fscrypt_restore_control_page(bounce_page);
+}
+EXPORT_SYMBOL(fscrypt_pullback_bio_page);
+
+void fscrypt_restore_control_page(struct page *page)
+{
+	struct fscrypt_ctx *ctx;
+
+	ctx = (struct fscrypt_ctx *)page_private(page);
+	set_page_private(page, (unsigned long)NULL);
+	ClearPagePrivate(page);
+	unlock_page(page);
+	fscrypt_release_ctx(ctx);
+}
+EXPORT_SYMBOL(fscrypt_restore_control_page);
+
+static void fscrypt_destroy(void)
+{
+	struct fscrypt_ctx *pos, *n;
+
+	list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list)
+		kmem_cache_free(fscrypt_ctx_cachep, pos);
+	INIT_LIST_HEAD(&fscrypt_free_ctxs);
+	mempool_destroy(fscrypt_bounce_page_pool);
+	fscrypt_bounce_page_pool = NULL;
+}
+
+/**
+ * fscrypt_initialize() - allocate major buffers for fs 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 fscrypt_initialize(void)
+{
+	int i, res = -ENOMEM;
+
+	if (fscrypt_bounce_page_pool)
+		return 0;
+
+	mutex_lock(&fscrypt_init_mutex);
+	if (fscrypt_bounce_page_pool)
+		goto already_initialized;
+
+	for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
+		struct fscrypt_ctx *ctx;
+
+		ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
+		if (!ctx)
+			goto fail;
+		list_add(&ctx->free_list, &fscrypt_free_ctxs);
+	}
+
+	fscrypt_bounce_page_pool =
+		mempool_create_page_pool(num_prealloc_crypto_pages, 0);
+	if (!fscrypt_bounce_page_pool)
+		goto fail;
+
+already_initialized:
+	mutex_unlock(&fscrypt_init_mutex);
+	return 0;
+fail:
+	fscrypt_destroy();
+	mutex_unlock(&fscrypt_init_mutex);
+	return res;
+}
+EXPORT_SYMBOL(fscrypt_initialize);
+
+/**
+ * fscrypt_init() - Set up for fs encryption.
+ */
+int __init fscrypt_init(void)
+{
+	fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
+							WQ_HIGHPRI, 0);
+	if (!fscrypt_read_workqueue)
+		goto fail;
+
+	fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT);
+	if (!fscrypt_ctx_cachep)
+		goto fail_free_queue;
+
+	fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
+	if (!fscrypt_info_cachep)
+		goto fail_free_ctx;
+
+	return 0;
+
+fail_free_ctx:
+	kmem_cache_destroy(fscrypt_ctx_cachep);
+fail_free_queue:
+	destroy_workqueue(fscrypt_read_workqueue);
+fail:
+	return -ENOMEM;
+}
+module_init(fscrypt_init)
+
+/**
+ * fscrypt_exit() - Shutdown the fs encryption system
+ */
+void __exit fscrypt_exit(void)
+{
+	fscrypt_destroy();
+
+	if (fscrypt_read_workqueue)
+		destroy_workqueue(fscrypt_read_workqueue);
+	kmem_cache_destroy(fscrypt_ctx_cachep);
+	kmem_cache_destroy(fscrypt_info_cachep);
+}
+module_exit(fscrypt_exit);
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index b0aed92..09fbcfb 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -236,4 +236,63 @@ static inline int fscrypt_has_encryption_key(struct inode *inode)
 	return 0;
 #endif
 }
+
+/* crypto.c */
+extern struct kmem_cache *fscrypt_info_cachep;
+int fscrypt_initialize(void);
+
+#ifdef CONFIG_FS_ENCRYPTION
+/* crypto.c */
+struct fscrypt_ctx *fscrypt_get_ctx(struct inode *);
+void fscrypt_release_ctx(struct fscrypt_ctx *);
+struct page *fscrypt_encrypt_page(struct inode *, struct page *);
+int fscrypt_decrypt_page(struct page *);
+void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
+void fscrypt_pullback_bio_page(struct page **, bool);
+void fscrypt_restore_control_page(struct page *);
+int fscrypt_zeroout_range(struct inode *, pgoff_t, sector_t, unsigned int);
+#else
+/* crypto.c */
+static inline struct fscrypt_ctx *fscrypt_get_ctx(struct inode *i)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void fscrypt_release_ctx(struct fscrypt_ctx *c)
+{
+	return;
+}
+
+static inline struct page *fscrypt_encrypt_page(struct inode *i, struct page *p)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline int fscrypt_decrypt_page(struct page *p)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *c,
+						struct bio *b)
+{
+	return;
+}
+
+static inline void fscrypt_pullback_bio_page(struct page **p, bool b)
+{
+	return;
+}
+
+static inline void fscrypt_restore_control_page(struct page *p)
+{
+	return;
+}
+
+static inline int fscrypt_zeroout_range(struct inode *i, pgoff_t p,
+					sector_t s, unsigned int f)
+{
+	return -EOPNOTSUPP;
+}
+#endif
 #endif	/* _LINUX_FSCRYPTO_H */
-- 
2.6.3

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